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Polyphenols and Antioxidant Properties of Almond Skins: Influence of Industrial Processing

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Abstract

Almond (Prunus dulcis[Mill.] D.A. Webb) skins have been proposed as a source of bioactive polyphenols. In this article, the phenolic composition and antioxidant activity of almond skins obtained from different processes (blanching [freeze-drying], blanching + drying, and roasting) were studied. A total of 31 phenolic compounds corresponding to flavan-3-ols (33% to 56% of the total of phenolic compounds identified), flavonol glycosides (9% to 36%), hydroxybenzoic acids and aldehydes (6% to 26%), flavonol aglycones (1.7% to 18%), flavanone glycosides (3% to 7.7%), flavanone aglycones (0.69% to 5.4%), hydroxycinnamic acids (0.65% to 2.6%), and dihydroflavonol aglycones (0% to 2.8%) were determined in the skins from 3 different varieties of almonds. The total contents of phenolic compounds identified were significantly (P < 0.05) higher (around 2-fold) in the roasted samples than in the blanched almonds (freeze-dried). Industrial drying (oven drying) of the blanched almond skins produced an increase (< 2-fold) in the contents of phenolic compounds, although the results were only statistically significant (P < 0.05) for some samples. The antioxidant activity (ORAC values) was higher for the roasted samples (0.803 to 1.08 mmol Trolox/g), followed by the samples subjected to blanching + drying (0.398 to 0.575 mmol Trolox/g) and then the blanched (freeze-dried) samples (0.331 to 0.451 mmol Trolox/g). Roasting is the most suitable type of industrial processing of almonds to obtain almond skin extracts with the greatest antioxidant capacity.

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... The first processing step in the production of these delicacies is the removal of the brown skin from almonds, by means of blanching in hot water and subsequent mechanical peeling. Skins account for 6-8% of the seed (Garrido, Monagas, Gómez-Cordovés, & Bartolomé, 2008) and are mainly destined to cattle feeding (Grasser, Fadel, Garnett, & DePeters, 1995). Blanching water represents merely a waste, and the producers have to face costs for its disposal. ...
... However, blanched skins and blanching water contain several antioxidant bioactive phenolic compounds, mainly composed of flavonoids, hydrolysable and condensed tannins and phenolic acids (Bolling, 2017;Chen, Milbury, Lapsley, & Blumberg, 2005;Garrido et al., 2008;Mandalari et al., 2010), that act synergistically to protect LDL from oxidation (Amarowicz, 2016;Chen, Milbury, Chung, & Blumberg, 2007). To increase the value of almond by-products, so as to reduce economic and environmental issues, the bioactive compounds could be extracted or, alternatively, the by-products themselves could be used as food ingredients. ...
... The phenolic compounds were extracted from 1 g of blanched almond skins either not dried or dried in different conditions (60°C for 30 min; 45°C for 90 min; 32°C for 150 min; 38-40°C for 6-8 h) according to three different protocols: "A", "B" and "C" (Fig. 1). The A and C protocols were modifications of extracting methods proposed by Garrido et al. (2008) and Mandalari et al. (2010), respectively. Modification consisted of substituting the extracting solvent (methanol acidified with 1 mL/L HCl 12 mol/L) with a solution of acetone diluted with 200 mL/L distilled water, based on a preliminary comparison of the extracting efficiency of these two different solvent combinations. ...
Article
Blanched skins and blanching water, by-products of almond processing, were evaluated as potential ingredients of bakery products. The research included three phases: i) optimization of skin drying; ii) optimization of quali-quantitative determination of phenolic compounds, by comparing three extracting protocols; iii) assessment of the impact of by-products on the rheology of composite doughs with wheat flour. The least time-consuming drying mode (at 60 °C for 30 min) retained better odor notes, higher content of phenolics (814 μg/g d.m. by HPLC, with the most effective extracting method) and greater antioxidant activity than sun-drying. Blanching water showed 917 μg/mL phenolics. Dried almond skins altered alveograph and farinograph indices of dough at doses higher than 30 and 50 g/kg, respectively, whereas blanching water did not cause significant changes. Therefore, almond skins could be used in products tolerating weak gluten network, such as cookies, whereas blanching water could be added to any bakery good.
... Total phenolic content (mg/g) gallic acid equivalents (GAE), total proanthocyanidins (mg/100 g) and total flavonoids (mg/100 g) in almonds, almond oil and defatted almond cake. [58,110,111,118,120] Naringenin 0.01-9.74 0.03-20.6 ...
... 0.03-20.6 [58,110,111,116,118,120,126,127,129] Naringenin-7-O-glucoside 0-5.88 0.04-14.3 [58,110,111,118,120,126,127,129] Flavonol Isorhamnetin 0.005-3.20 0.40-4.55 ...
... [58,110,111,116,118,120,126,127,129] Naringenin-7-O-glucoside 0-5.88 0.04-14.3 [58,110,111,118,120,126,127,129] Flavonol Isorhamnetin 0.005-3.20 0.40-4.55 [58,110,111,118,120,[124][125][126][127][128][129][130] Isorhamnetin-3-O-galactoside 0.30-0.92 ...
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This work presents a bibliographic review about almond kernel non-lipid components, in particular about the protein fraction, the carbohydrates and the mineral fraction. In addition, other fat-soluble phytochemicals which are present in minor concentrations but show important antioxidant activities are reviewed. Almond kernel is a rich protein food (8.4-35.1%), in which the globulin-albumin fraction dominates, followed by glutelins and prolamins. Within the almond kernel protein profile, amandine dominates. Free amino acids represent a small amount of the total nitrogen quantity, highlighting the presence of glutamic acid and aspartic acid, followed by arginine. Carbohydrates that appear in almond kernels (14-28%) are soluble sugars (mainly sucrose), starch and other polysaccharides such as cellulose and non-digestible hemicelluloses. Regarding the mineral elements, potassium is the most common, followed by phosphorus; both macronutrients represent more than 70% of the total mineral fraction, without taking into account nitrogen. Microminerals include sodium, iron, copper, manganese and zinc. Within the phytochemical compounds, tocopherols, squalene, phytosterols, stanols, sphingolipids, phospholipids, chlorophylls, carotenoids, phenols and volatile compounds can be found.
... Raw almonds contain amounts of a bound form of antioxidant phenols (glycosylated flavonols, high polymerized proanthocyanidins of low extractability, and others) 132,133 which might suffer breakage of these covalently bound polymeric compounds and liberate the free forms with antioxidant activity. This could be the case of p-hydroxybenzoic acid, t-ferulic acid, and vanillic acid, which are cell-wall bound phenolic compounds and their release enhances the overall antioxidant activity of almonds. ...
... The total polyphenol content in roasted almonds was approximately 2-fold higher compared to blanched + freezedried almonds and less than 2-fold higher compared to blanched + oven-dried almonds (Table 4). 133 The thermal processing applied (blanching at 95°C, roasting at 145°C and drying at 60°C) led to decomposition of aglycones and degradation of the polymerized proanthocyanidins. Furthermore, the solubilization of more polar components could be favored by the contact of the skin with water during the blanching procedure. ...
... Significant differences, as expressed by the ORAC values, were detected between the three types of thermal processing described above (Table 5): roasting > blanching + oven-drying > blanching + freeze-drying. 133 A possible explanation could be that antioxidant compounds from the skin are solubilized in the blanching water and then they are biodegraded at high temperatures, leading to a decrease in bioactive compounds in the blanched samples. On the other hand, Maillard reaction products can be formed during the drying and roasting procedures, thus enhancing the antioxidant capacity of roasted almond skins. ...
Article
Tree nuts, complete functional foods, contain macro and micronutrients of high biological value. These bioactive compounds have a synergistic effect in preventing and delaying many age-related pathologies (e.g. cardiovascular diseases, stroke, type 2 diabetes mellitus, certain types of cancer, several neurodegenerative diseases). Tree nuts are low in carbohydrates, but they abound in healthy fatty acids, in optimal proportion for a good plasma lipid profile, and are a good source of proteins, rich in proteinogenic amino acids. They contain important amounts of vitamin E, minerals, polyphenols, and phytosterols. Polyphenols, powerful phytochemicals, act as direct and indirect antioxidants, reduce the inflammatory response, improve proteostasis and mitochondrial biogenesis, modulate many cell signaling pathways, have a major role in cytoprotection, are Nrf2/ARE activators, down-regulate the NFкB system, promote anticancer potential, and prevent cell senescence. Some of them have senolytic effect, interfere in specific cell signaling pathways modulated by caloric restriction, protect against UV radiation and photoaging. Moreover, tree nuts are good prebiotics and improve gut microbiota. The stability of polyphenolic compounds and their antioxidant activity can be influenced by cooking techniques, temperature storage, post-harvest processing methods. The consumption of tree nuts is scientifically proven to improve lifespan and healthspan and should be part of a healthy diet in the elders.
... Furthermore, the term estimation implies that in depth analysis (e.g., liquid chromatography-tandem mass spectrometry, LC-MS n ) should be further carried out. [191]; (B) hazelnut skin [192]; (C) rice husk [193]; (D) soybean coat [194]; (E) canola (high-tannin) and rapeseed (low-tannin) hull [195], S1, S2, and S3 are sample 1, 2, and 3, respectively; (F) grape seed and peel [196]. Abbreviations: GAE, gallic acid equivalents; CE, catechin equivalents; TAE, tannin acid equivalents; FAE, ferulic acid equivalents; CAE, chlorogenic acid equivalents; and SAE, sinapic acid equivalents. ...
... The study by Garrido et al. [191] ( Figure 4A) demonstrated that total phenolics increased upon different heat processing operations. However, this may be misleading since a deeper evaluation of their data shows that some individual phenolics were not affected by the treatment (e.g., procyanidin trimer A) while some (e.g., eriodictyol-7-O-glucoside, kaempferol, isorhamnetin) were actually decreased after blanching and drying. ...
... The phenolic compounds identified in skin samples allowed finding differences among the cultivars. These results agree with the ones obtained by Garrido et al. [80] carried out in different almond skins related to the phenolic composition. Moreover, in the work carried out by Valdés et al. [72], LDA was successfully applied by using the total phenolic content (TPC), the antioxidant activity measured by FRAP and individual flavonoid contents as predictors, obtaining a 100% correctly classification of the blanched samples according to each cultivar. ...
... Regarding the TPC expressed as mg gallic acid equivalent (GAE) g −1 almond; Butte and Fritz showed the lowest values (58 ± 7) being Sonora samples the ones with the highest value (159 ± 1). In all the samples, the main phenolic compounds were [80,81] Regarding unblanched raw almond kernels, the antioxidant activity and phenolic profile corresponding to Marcona, Texas and Troito samples grown in Serbia were evaluated byČolić et al. [18]. The obtained TPC values were 204, 1195, and 271 mg GAE kg −1 kernel respectively, and the predominant polyphenol found was catechin, followed by chlorogenic acid and naringenin. ...
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Almonds show a great variability in their chemical composition. This variability is a result of the existence of a diverse range of almond cultivars, the self-incompatibility of most almond cultivars, and the heterogeneous harvesting conditions found around the different locations where almons are grown. In the last years, the discrimination among almond cultivars has been the focal point of some research studies to avoid fraud in protected geographical indications in almond products and also for selecting the best cultivars for a specific food application or the most interesting ones from a nutritional point of view. In this work, a revision of the recent research works related to the chemical characterization and classification of almond cultivars from different geographical origins has been carried out. The content of macronutrients, tocopherols, phytosterols, polyphenols, minerals, amino acids, and volatile compounds together with DNA fingerprint have been reported as possible cultivar and origin markers. The analysis of the results showed that no individual almond compound could be considered a universal biomarker to find differences among different almond cultivars. Hence, an adequate selection of variables or the employment of metabolomics and the application of multivariate statistical techniques is necessary when classification studies are carried out to obtain valuable results. Meanwhile, DNA fingerprinting is the perfect tool for compared cultivars based on their genetic origin
... The TPC values of both ASFC and ASFF were higher than those obtained Bolling et al. [32] in almond skins obtained from nonpareil, carmel, butte, sonora, fritz, mission and monterey cultivars harvested in California with values comprise between 58 and 159 mg gallic acid equivalents/100 g sample. However, Garrido et al. [33] reported that the total phenols content present in the almonds skins obtained from cultivars of Spain and America varied from 0.91 to 3.21 g/100g. These values were higher than those reported in this work. ...
... For tannin content, again ASFC showed higher values (p < 0.05) than ASFF. The results obtained in this study were similar than those found by Garrido et al. [33] in almond skins obtained from cultivars of Spain and America with values comprised between 5.81 and 43.3 mg/g of peel powder. ...
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The goals of this research were determined the proximate composition, physico-chemical, techno-functional properties, the polyphenolic profile, the organic acids and sugar content and the antioxidant capacities of flours obtained from almonds skins var. comuna (ASFC) and var. fritz (ASFF) coproducts produced in Turrón industry. The chemical composition and physico-chemical properties (pH, water activity and color) were determined. The water holding, oil holding and swelling capacities were also determined, as well as the polyphenolic profile. For the antioxidant capacity, four different assays were used namely: 2,2-diphenyl-1-picrylhydrazyl radical scavenging assay (DPPH•); Ferrous ions chelating activity (FIC); Ferric reducing antioxidant power (FRAP) and 2,2′-azinobis-(3-ethylbenzothiazoline-6-sulfonic acid) radical scavenging assay (ABTS•+). The flours obtained from ASFC and ASFF had a high content of dietary fiber (70.50 and 69.83 g/100 g, respectively). The polyphenolic profile, determined by High Performance Liquid Chromatography, identified 21 and 19 polyphenolic compounds in both ASFC and ASFF, being epicatechin and catechin the most abundant compounds. In reference to the antioxidant capacity regards, with all methods assayed except FRAP, ASFC had higher antioxidant activity than ASFF. These coproducts show good technological and antioxidant properties, which makes them a good alternative for its use in the development of new foods.
... In addition, nuts provide a wide range of nutrients, such as vitamins (folic acid, niacin, tocopherols, vitamin B6, etc.), minerals (calcium, magnesium, potassium, etc.) and many other bioactive components, such as phytosterols (Phillips et al., 2005;Segura et al., 2006) and phenolic compounds, which act as powerful antioxidants in the body (Chang et al., 2016). In most nuts, these antioxidants are located in the skin, as occurs in almonds (Garrido et al., 2008;Chen et al., 2019), hazelnuts and pistachios (Arcan and Yemenicioglu, 2009), walnuts (Jahanban-Esfahlan et al., 2019) and peanuts (Lou et al., 2004). This means that after peeling, a large part of the antioxidant capacity of the fruits is lost. ...
... This means that after peeling, a large part of the antioxidant capacity of the fruits is lost. Something similar happens with industrial bleaching, which is applied for peeling purposes and causes antioxidant activity to be reduced, as has been shown for almonds (Garrido et al., 2008;Oliveira et al., 2020) and peanuts (Yu et al., 2006). However, roasting in general increases the antioxidant activity in nuts (Chang et al., 2016). ...
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Nuts are important components of a healthy diet since they provide nutritional value and bioactive components. Melatonin is a well-known molecule in plants, and its relevance in foodstuffs is increasing. This study investigated the presence of melatonin in nuts using chromatographic techniques and optimized extraction procedures according to the high oil content of nuts. Melatonin was detected in four walnut cultivars with levels similar to those previously reported. Moreover, the melatonin content in walnut seeds decreased sharply during the ripening process from the ripe green stage to the mature dehydrated fruit and increased after harvesting when the fruits were edible. A number of other commercial nuts were also measured, with melatonin contents varying markedly, and generally being lower than in walnuts. The presence of melatonin was lower in commercial roasted nuts than in raw nuts, with the exception of peanuts, where melatonin content increased with roasting. It seems that this industrial processing negatively alters the structure of this molecule and its availability, which should be taken into account when estimating its levels during nut consumption. Therefore, this study reveals new data on the presence of melatonin in walnut seeds in a natural format and its evolution with maturation as well as in other commercial nuts. We also highlight the importance that processing has on melatonin and other antioxidants in the nuts that reach the consumer.
... The antioxidant activity (AA) is related to the ability of almonds to reduce pro-oxidant agents; AA is considered a key quality feature by consumers because an increase in the consumption of antioxidant compounds was associated with reduced obesity in women and also helped in reducing the risk of stroke and cardiovascular diseases, and even some cancer types [21]. Almond polyphenols are mostly found in its skin, with values ranging from 9.10 to 32.1 g kg −1 (skin values obtained from blanched and roasted almonds, freeze-dried or dried in a hotair oven at 60 °C) [22]. However, almond skin is often removed by blanching for commercial reasons and this unit operation will drastically reduce the polyphenol content. ...
... Blanched kernel TPC (0.5 g GAE kg −1 ) was similar to that reported in literature (0.7 g GAE kg −1 ) for almonds in general [30]. Finally, a mean TPC value of 13 g GAE kg −1 was found on almond skin and similar values were reported for American almonds (11-17 g GAE kg −1 ), but lower values were found for Spanish almonds (26 g GAE kg −1 ) [22]. ...
Article
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The influence of full irrigation, double-regulated (RDI) and sustained deficit irrigation (SDI) treatments on almond quality was assessed by analyzing different parameters: sugars, organic acids, antioxidant activity, total phenolic content (TPC), and volatile compounds. Almond quality studies for plants submitted to water stress are scarce, and it is essential to understand the biochemical responses of plants to water stress in maintaining fruit yield and quality. Citric acid, sucrose, antioxidant activity, and TPC were not affected by the application of studied deficit irrigation strategies (DI). An increase in malic acid and a decrease in glucose was observed for stressed samples (T3 and T4), while a higher number of total volatiles compounds was found for moderate RDI (T2). Using deficit irrigation strategies, the almond yield and quality was not changed, and in fact, some parameters, such as glucose and key volatile compounds, slightly increased under moderate RDI. This finding might encourage farmers to implement these strategies and contribute to sustainable agriculture.
... These functional metabolites may have useful applications in medical and ornamental industries. In plants, phenolic acids and flavonoids are low-molecular-weight pervasive groups (Ghasemzadeh and Ghasemzadeh, 2011;Rehman et al., 2018). Phenolic compounds are carbon-based secondary metabolites, which act as powerful antioxidants, antiviral, and anti-allergic agents (Yagi et al., 2013;Rouphael et al., 2017). ...
... The stone fruits such as peach, sweet cherry, apricot, plums, and almond skin have a diversity of polyphenols. However, catechin, epicatechin, chlorogenic acid derivatives are the most common among detected polyphenols in these fruits (Garrido et al., 2008;Campbell and Padilla-Zakour, 2013;Pinu, 2016;Koprivica et al., 2018). Previous research revealed several health-promoting benefits of polyphenols obtained from plants (Lara et al., 2020). ...
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Macadamia ternifolia is a dynamic oil-producing nut crop in the world. However, the nutshell is frequently considered as a low-quality material. Further, its metabolic profile is still uncharacterized. In order to explore the industrial significance of the nutshell, this study performed metabolic and transcriptomic analyses at various developmental stages of the nutshell. The qualitative and quantitative metabolic data analysis identified 596 metabolic substances including several species of phenolic acids, flavonoids, lipids, organic acids, amino acids and derivatives, nucleotides and derivatives, alkaloids, lignans, coumarins, terpenoids, tannins, and others. However, phenolic acids and flavonoids were predominant, and their abundance levels were significantly altered across various developmental stages of the nutshell. Comparative transcriptome analysis revealed that the expression patterns of phenolic acid and flavonoid pathway related genes were significantly changed during the nutshell growth. In particular, the expression of phenylalanine ammonia-lyase, C4H, 4CL, CHS, CHI, F3H, and FLS had dynamic differences at the various developmental stages of the nutshell. Our integrative metabolomic and transcriptomic analyses identified the key metabolic substances and their abundance levels. We further discussed the regulatory mechanism of phenolic and flavonoid biosynthesis in the nutshell of M. ternifolia. Our results provide new insights into the biological profiles of the nutshell of M. ternifolia and help to elucidate the molecular mechanisms of phenolic and flavonoid biosynthesis in the nutshell of M. ternifolia .
... (Poly)phenols are highly influenced by diverse causes, variations concerning the phenolic content of almond skins already being described based on different factors: variety (Barreira et al., 2010), industrial processing and storage (Bolling et al., 2010a;Garrido et al., 2008;Pasqualone et al., 2018), agro-climatic conditions corresponding to distinct years (Bolling et al., 2010b), while low or almost none attention has been dedicated to the influence of the agronomical management practices (such as irrigation strategies). ...
... The phenolic content present in skins appeared more influenced by the season, while a lower effect of the different irrigation treatments assayed in the present work was observed. Garrido et al. (2008) and Bartolomé et al. (2010) have previously demonstrated that total phenolic content of almond skin from mixtures of Spanish and American varieties, obtained upon diverse seasons, varied between 9.10 and 32.10 mg GAE/g DW, with differences of almost 35.0% between seasons 2004 and 2006. ...
Article
Almond (Prunus dulcis (Mill.) D. A. Webb) production keeps an increasing trend worldwide, leading to augment in generation of harmful by-products that should be valorized as a source of bioactive phytochemicals with application in the development of new added-value products. The assessment of almond hulls and skins on their (poly)phenolic composition was developed upon two seasons, under five irrigation regimes, regarding total phenolics, flavonoids, and ortho-diphenols, as well as individual phenolic compounds analyzed by High-Performance Liquid Chromatography with Diode-Array Detection (HPLC-DAD). As functional tests, extracts were assessed on their radical scavenging activity in vitro and reducing power, and screened on their antimicrobial activity against multidrug resistant bacterial pathogens. The phenolic profile and antioxidant activities were evaluated in blanching water as well. Naringenin-7-O-glucoside and isorhamnetin-3-O-rutinoside were the most abundant phenolics in almond hulls and skins. Influence of irrigation treatments and season on phenolic content differed among by-products; hulls being more influenced by irrigation and skins by the agro-climatic conditions. The synthesis of individual phenolics was more influenced by season than treatment. According to the chemical and biological correlations, the presence of (poly)phenols seems to be responsible for the antioxidant and antimicrobial properties revealed. The knowledge generated upon the present work contributes to understand the variability of almond by-products composition attributable to seasonal and irrigation conditions, and to envisage valorization alternatives for these under explored residues and blanching water.
... Furthermore, the term estimation implies that in depth analysis (e.g., liquid chromatography-tandem mass spectrometry, LC-MS n ) should be further carried out. [191]; (B) hazelnut skin [192]; (C) rice husk [193]; (D) soybean coat [194]; (E) canola (high-tannin) and rapeseed (low-tannin) hull [195], S1, S2, and S3 are sample 1, 2, and 3, respectively; (F) grape seed and peel [196]. Abbreviations: GAE, gallic acid equivalents; CE, catechin equivalents; TAE, tannin acid equivalents; FAE, ferulic acid equivalents; CAE, chlorogenic acid equivalents; and SAE, sinapic acid equivalents. ...
... The study by Garrido et al. [191] ( Figure 4A) demonstrated that total phenolics increased upon different heat processing operations. However, this may be misleading since a deeper evaluation of their data shows that some individual phenolics were not affected by the treatment (e.g., procyanidin trimer A) while some (e.g., eriodictyol-7-O-glucoside, kaempferol, isorhamnetin) were actually decreased after blanching and drying. ...
Article
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Plant foods, their products and processing by-products are well recognized as important sources of phenolic compounds. Recent studies in this field have demonstrated that food processing by-products are often richer sources of bioactive compounds as compared with their original feedstock. However, their final application as a source of nutraceuticals and bioactives requires addressing certain hurdles and challenges. This review discusses recent knowledge advances in the use of plant food processing by-products as sources of phenolic compounds with special attention to the role of genetics on the distribution and biosynthesis of plant phenolics, as well as their profiling and screening, potential health benefits, and safety issues. The potentialities in health improvement from food phenolics in animal models and in humans is well substantiated, however, considering the emerging market of plant food by-products as potential sources of phenolic bioactives, more research in humans is deemed necessary.
... mg in GAE/g in the 'Uzun' cultivar. The results are similar with previous research which used pistachio and other types of nuts (Haard, 1976;Garrido, Monagas, Gómez-Cordovés, and Bartolomé, 2008;Chandrasekara & Shahidi, 2011;Rodríguez-Bencomo et al., 2015). Heat treatment may release more bound phenolic acids from the breakdown of cellular components (Haard, 1976). ...
... Food Chemistry 272 (2019) 418-426 all phenolics. Similarly, Garrido, et al. (2008) reported that industrial processing (e.g., roasting, freeze drying, and mincing) affects the phenolic content and antioxidant capacity of almonds. The researchers stated that the roasting and freeze drying increased the total phenolic content and antioxidant capacity of the samples. ...
Article
The aim of this study was to identify phenolic compounds and measure the physicochemical properties of two pistachio (Pistacia vera L.) cultivars (‘Uzun’ and ‘Ohadi’). For this purpose, the pistachios were subjected to four different hulling methods (wet hulling-WT, brine hulling-BR, wet-dry hulling-WD, and dry-dry hulling-DD) and a standard roasting treatment. Phenolic compounds were analyzed by HPLC-DAD-ESI-MSⁿ. Twelve phenolics were identified and quantified in the samples, 10 of which were flavonoid and two non-flavonoid phenolic acids. In both cultivars, the major compounds were found to be gallic acid and catechin followed by eriodictyol-7-O-glucoside and eriodictyol. The dry-dry hulling method treated sample had higher antioxidant capacity, total phenol content, and phenolic compounds than the other hulling methods in both pistachio cultivars. After the roasting treatment, the antioxidant capacity, phenolic content, and a∗ value increased while the L∗ and b∗ values decreased.
... A remoção desta película (tegumento) é normalmente feita em duas etapas: branqueamento com água quente e subsequente descasque mecânico. Tendo em conta que a película representa 6-8% da massa do endosperma (Garrido et al., 2008), serão geradas entre 108 e 144 toneladas deste subproduto. Admitindo que a produção de amêndoa duplicará nos próximos anos e que o processamento evolui ao mesmo ritmo, podem, num futuro próximo, ser geradas mais de 280 toneladas deste material. ...
... Atualmente, estas películas são quase inteiramente destinadas à alimentação animal ou utilizadas como combustível em instalações industriais (Harrison e Were, 2007). No entanto, contêm, tal como a água que remanesce do processo de branqueamento, elevados teores de compostos fenólicos (maioritariamente flavonoides, taninos condensados, taninos hidrolisáveis e ácidos fenólicos) e uma considerável atividade antioxidante (Garrido et al., 2008;Mandalari et al., 2010;Bolling, 2017), com particular interesse a nível da proteção contra a oxidação do colesterol LDL (Chen et al., 2007;Amarowicz, 2016). ...
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Almond was once one of the main export products from the agricultural sector in Portugal. However, the growing presence on the world market of almonds produced in California at very low prices and the depopulation of rural areas, especially since the 1970s, led to the progressive abandonment of almond cultivation. Almond tree [Prunus dulcis (Mill.) D. A. Webb], however, has never ceased to be an emblematic species in Portugal. Although with low economic value it continued to create stunning landscapes, with its early flowering, attracting tourists to the inland, in particular to the Douro Valley and tributaries, where it has always maintained some value for the family income. In recent years, there has been a renewed interest in this species. The increase in the consumption of almonds worldwide has created conditions for prices to remain a little more attractive than in previous years, which, together with the general failure of the dryland arable sector (cereals in particular) in the inland of the country, has stimulated the appearance of new plantations of almond trees. The phenomenon is particularly relevant in Alentejo, associated to the new irrigation infrastructures, with intensive plantations, but also in Trás-os-Montes, where rainfed orchards prevail. The almond tree has been valued for the edible part of the nut and occasionally in winter tourist routes associated with flowering, as mentioned. However, several by-products of the almond tree can be valorized, especially those that present greater quantitative expression such as hull (2000 t year-1), shell (9000 t year-1), tegument (120 t year-1) and pruning wood (25000 t year-1). In this work, an estimate is made of the quantity of the by-products produced in Portugal and clues for their potential uses presented.
... flavonoids, phenolic acids, tannins, and vitamin E(Rao et al., 2012). Polyphenols, phenolic acids, flavonoids, and tannins contribute to the antioxidant properties of almonds(Milbury et al., 2006;Garrido et al., 2008). The composition and abundance of these molecules completely depend on the variety(Milbury et al., 2006; Barriera et al., 2008). ...
... flavonoids, phenolic acids, tannins, and vitamin E (Rao et al., 2012). Polyphenols, phenolic acids, flavonoids, and tannins contribute to the antioxidant properties of almonds(Milbury et al., 2006;Garrido et al., 2008). The composition and abundance of these molecules depend entirely on variation(Milbury et al., 2006; Barriera et al., 2008). ...
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Almond is a temperate climate fruit that should be grown with appropriate rootstocks, convenient variety combinations, and reproductive trees with quality fruits. Fruit tree rootstocks affect the fruit pomological characteristics, yield, fruit quality, and plant nutrient content of the grafted varieties. In this study, the pomological properties (The weight of the shelled fruits and kernels, length, width, thickness, kernel yield), yield, antioxidant capacities, total phenol contents, fatty acids, and nutrient contents of the 'Ferragnes' and 'Ferraduel' varieties, which are grafted on Garnem, GF 677 and Seedling rootstock were determined for two years. Nitrogen (N) analyses carried out on the leaves were found to be significantly higher in samples taken from Garnem and GF-677 rootstocks grafted with the ‘Ferraduel’ variety with the ratio of 2.29% and 2.44%, respectively. Phosphorus (P) content was found to be the highest at 0.35% in the ‘Ferraduel’ almond variety grafted on GF-677 rootstock. In Potassium (K) analyses, a high value of 0.67% was observed in fruit samples taken from ‘Ferraduel’ grafted on Garnem trees in the first year. Magnesium (Mg) levels did not differ in fruit samples, while was the highest in leaves taken from ‘Ferraduel’ grafted on Garnem trees with a rate of 1.27%. Palmitic, palmitoleic, stearic, oleic, linoleic, and linolenic acid were the main fatty acids in almond samples. Antioxidant activities of almonds grown in different rootstocks ranged between 4.80-9.50 μ mol TE/g FW, and total phenol content between 56.21-133.14 mg GAE/100 g FW. The antioxidant and phenol x content of Seedling rootstocks were found to be high compared to GF-677 rootstock and Garnem rootstock. The fruit size of both almond varieties grown on Seedling rootstock and Garnem rootstock were found to be higher than those of Garnem rootstock. The kernel yield average for both years was found to be 22.14% in Seedling/Ferraduel, 23.21% in Garnem/Ferraduel, 23.59% in GF-677/Ferraduel, 33.82% in Seedling/Ferragnes, 32.57% in Garnem/Ferragnes, and 34.12% GF677/Ferragnes. Although the almond weights and lengths were higher in the Seedling rootstock, the kernel yields of the other two clone rootstocks were found to be high. The yield values of the ‘Ferraduel’ cultivar were determined as 6.38 kg per tree on average, 14.8 kg on Garnem rootstock, and 12.36 kg on GF-677 rootstock; In the Ferragnes variety, it was determined as 5.9 kg in the Seedling rootstock, 16.34 kg in the Garnem rootstock, and 13.29 kg in the GF-677 rootstock. Considering that the yield values of GF-677 rootstock were high, GF-677 rootstock was determined to be suitable for ‘Ferragnes’ and ‘Ferraduel’ almond cultivation.
... Thus, the effect of polyphenols on GPx activity and GSH status appears to depend on sample type (plasma vs. erythrocytes), flavonoid class (anthocyanins vs. flavonols), and study design (chronic vs. acute). Establishing an efficient extraction protocol to produce a commercial, high-quality polyphenol-rich product from almond skins for human use remains a challenge, though use of almond skin powder can already be found in the marketplace [57]. ...
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Almond skins are a waste byproduct of blanched almond production. Polyphenols extracted from almond skins possess antioxidant activities in vitro and in vivo. Thus, we examined the pharmacokinetic profile of almond skin polyphenols (ASP) and their effect on measures of oxidative stress. In a randomized crossover trial, seven adults consumed two acute ASP doses (225 mg (low, L) or 450 mg (high, H) total phenols) in skim milk or milk alone. Plasma flavonoids, glutathione peroxidase (GPx), glutathione (GSH), oxidized GSH (GSSG), and resistance of low- density lipoprotein (LDL) to oxidation were measured over 10 h. The H dose increased catechin and naringenin in plasma, with maximum concentrations of 44.3 and 19.3 ng/mL, respectively. The GSH/GSSG ratio at 3 h after the H doses was 212% of the baseline value, as compared to 82% after milk (p = 0.003). Both ASP doses upregulated GPx activity by 26–35% from the baseline at 15, 30, 45, and 120 min after consumption. The in vitro addition of α-tocopherol extended the lag time of LDL oxidation at 3 h after L and H consumption by 144.7% and 165.2% of that at 0 h compared to no change after milk (p ≤ 0.05). In conclusion, ASP are bioavailable and modulate GSH status, GPx activity, and the resistance of LDL to oxidation.
... The confectionery industry, in the production of blanched almonds, generates large quantities of almond skins as a by-product, which are mostly destined to cattle feeding [1] and composting [2]. However, almond skins can be considered functional food ingredients because they contain several bioactive phenolic compounds, namely flavonoids, phenolic acids, and tannins, the latter both hydrolysable and condensed [3][4][5][6][7]. The phenolic content of fresh almond skins comprises between 11.1 and 17.7 mg/g, depending on the extraction protocol [7], whereas 0.25-0.85 ...
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Upcycling food industry by-products has become a topic of interest within the framework of the circular economy, to minimize environmental impact and the waste of resources. This research aimed at verifying the effectiveness of using almond skins, a by-product of the confectionery industry, in the preparation of functional biscuits with improved nutritional properties. Almond skins were added at 10 g/100 g (AS10) and 20 g/100 g (AS20) to a wheat flour basis. The protein content was not influenced, whereas lipids and dietary fiber significantly increased (p < 0.05), the latter meeting the requirements for applying “source of fiber” and “high in fiber” claims to AS10 and AS20 biscuits, respectively. The addition of almond skins altered biscuit color, lowering L* and b* and increasing a*, but improved friability. The biscuits showed sensory differences in color, odor and textural descriptors. The total sum of single phenolic compounds, determined by HPLC, was higher (p < 0.05) in AS10 (97.84 µg/g) and AS20 (132.18 µg/g) than in control (73.97 µg/g). The antioxidant activity showed the same trend as the phenolic. The p-hydroxy benzoic and protocatechuic acids showed the largest increase. The suggested strategy is a practical example of upcycling when preparing a health-oriented food product.
... In order to design successful valorization alternatives for almond by-products as sources of bioactive phenolics, optimizing extraction constitutes a crucial stage, while to date, the extraction of phenolic compounds present into these byproducts has been reported based on the use of diverse solvents of analytical grade (and therefore, no usable by the pharma and food industries), and regarding acidity, and extraction times, upon different extraction technologies (Pinelo et al. 2004;Wijeratne et al. 2006;Rubilar et al. 2007;Garrido et al. 2008;Mandalari et al. 2010c;Valdés et al. 2015). Therefore, further optimization procedures are still required on all three solid almond by-products, given the lack of information existing and diverse extraction technologies applicable to these materials. ...
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Response surface methodology (RSM) was chosen to optimize the influence of solvent pH and relative proportion, and time of extraction, regarding polyphenols and radical scavenging capacity of almond (Prunus dulcis (Mill.) D.A. Webb) by-products (hulls, shells, and skins) from an almond orchard located in the North of Portugal (Lousa, Torre de Moncorvo). The RSM model was developed according to a Box-Behnken design and the optimal conditions were set for pH 6.5, 250.0 min, and 90.0% of food quality ethanol, pH 1.5, 235.0 min, and 63.0% ethanol, and pH 1.5, 250.0 min, and 56.0% ethanol for hulls, shells, and skins, respectively. The optimal conditions were obtained applying spectrophotometric techniques because of their versatility, while the chromatographic profile of extracts obtained when applied the optimal conditions indicated the presence of 3-caffeoylquinic acid, naringenin-7-O-glucoside, kaempferol-3-O-glucoside, isorhamnetin-3-O-rutinoside, isorhamnetin-3-O-glucoside, and isorhamnetin aglycone in hulls and skins. The model designed allowed the optimization of the phenolic extraction from almond by-products, demonstrating the potential of these materials as sources of antioxidant compounds with potential industrial, pharmaceutical, and food applications.
... Furthermore, the changes of individual phenolic compounds were observed (Kaiser et al., 2013b). Some researchers have shown that the phenolic content of blanched almond skin decreased during the blanching process, while the polyphenols were increased in blanch water (Milbury et al., 2006;Garrido et al., 2008;Mandalari et al., 2010;Hughey et al., 2012). Blueberries are rich in polyphenols, which have physiological activities such as antioxidant, antiinflammatory, etc. ...
... This hypothesis is supported by the significantly higher value of the K 232 , a marker of lipid oxidation phenomena in almonds [46] observed in CAcv, as compared with FCcv. Phenol compounds and their bioaccessibility contribute to healthy nutraceutical effects of almonds; for example phenol compounds in almond skin have been linked with positive health effects as the reduction of oxidative stress and inflammation [47][48][49][50][51][52]. A number of studies also link the consumption of almonds with lower levels of serum cholesterol and triglycerides, due to their content in polyunsaturated fatty acids [10,11]. ...
Article
Background: Almonds are healthy nutraceuticals, which vary across different cultivars. We compared the composition, agreeability and gastrointestinal effects of two almond cultivars from different areas. Methods: Californian Carmel (CAcv) and local Apulian Filippo Cea (FCcv) cultivars were compared for the chemical composition and sensory evaluation according to visual analogue and semiquantitative scales in 60 volunteers. Gallbladder/gastric motility (ultrasonography) and orocecal transit time (H2-breath test) were studied in another 24 subjects by comparing the effects of a standard liquid test meal with isovolumetric almond test meals (24 g of CAcv or FCcv almonds). Results: Proteins prevailed in CAcv, while FCcv contained more lipids and 10-times more total phenol content than CAcv. For agreeability, CAcv scored higher than FCcv for smell, texture and appearance, although different perceptions existed in lean (scores for smell, taste, texture, appearance higher for CAcv than FCcv), obese (CAcv better than FCcv only for appearance) and elderly subjects (CAcv better than FCcv only for texture). Gallbladder emptying was stronger with FCcv than CAcv. Antral dilatation after ingestion of both cultivars was greater than the dilatation observed after the test meal. Gastric emptying, however, was similar after FCcv, CAcv and the test meal. The orocecal transit time in response to both cultivars was shorter than after the test meal. Conclusions: Differences in composition and effects of FCcv and CAcv cultivars support their potential use as valuable nutraceutical tools, to be confirmed in further clinical studies.
... The influence of roasting, pasteurization and storage on the almond skins' polyphenol content has been widely investigated: Bolling et al. [32] reported that roasting led to a decrease in total phenols and ferric reducing antioxidant power but did not affect the amounts of flavonoids and phenolic acids. On the contrary, Garrido et al. [87] found that roasted almonds had the highest antioxidant activity in terms of ORAC values. It is well known that industrial blanching for the removal of the skin consistently reduces almonds' polyphenol content, since most of the water-soluble compounds end up in the water and the blanched skin [44,88]. ...
Article
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Almonds (Prunus dulcis Miller D. A. Webb (the almond or sweet almond)), from the Rosaceae family, have long been known as a source of essential nutrients; nowadays, they are in demand as a healthy food with increasing popularity for the general population and producers. Studies on the composition and characterization of almond macro- and micronutrients have shown that the nut has many nutritious ingredients such as fatty acids, lipids, amino acids, proteins, carbohydrates, vitamins and minerals, as well as secondary metabolites. However, several factors affect the nutritional quality of almonds, including genetic and environmental factors. Therefore, investigations evaluating the effects of different factors on the quality of almonds were also included. In epidemiological studies, the consumption of almonds has been associated with several therapeutically and protective health benefits. Clinical studies have verified the modulatory effects on serum glucose, lipid and uric acid levels, the regulatory role on body weight, and protective effects against diabetes, obesity, metabolic syndrome and cardiovascular diseases. Moreover, recent researchers have also confirmed the prebiotic potential of almonds. The present review was carried out to emphasize the importance of almonds as a healthy food and source of beneficial constituents for human health, and to assess the factors affecting the quality of the almond kernel. Electronic databases including PubMed, Scopus, Web of Science and SciFinder were used to investigate previously published articles on almonds in terms of components and bioactivity potentials with a particular focus on clinical trials.
... On the other hand, almond skin is a source of bioactive polyphenols and thus of antioxidant activity. About 30 phenolic compounds have been identified which include flavan-3-ols (the more abundant comprising proanthocyanidins, catechin, epicatechin), flavonol glycosides (kaempferol-3-O-rutinoside, kaempferol-3-O-glucoside, isorhamnetin-3-O-rutinoside, isorhamnetin-3-O-glucoside, and quercetin-3-O-glucoside), hydroxybenzoic acids (p-hydroxybenzoic acid, vanillic acid, and protocatechuic acid) and aldehydes (protocatechuic aldehyde), flavonol aglycones (kaempferol, quercetin, and isorhamnetin), flavanone glycosides (naringenin-7-O-glucoside and eriodictyol-7-O-glucoside), flavanone aglycones (naringenin and eriodictyol), hydroxycinnamic acids (trans-p-coumaric acid and chlorogenic acid), and dihydroflavonol aglycones (dihydroquercetin) ( Table 1, Garrido et al., 2008). ...
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Phytochemicals or secondary metabolites present in fruit are key components contributing to sensory attributes like aroma, taste, and color. In addition, these compounds improve human nutrition and health. Stone fruits are an important source of an array of secondary metabolites that may reduce the risk of different diseases. The first part of this review is dedicated to the description of the main secondary organic compounds found in plants which include (a) phenolic compounds, (b) terpenoids/isoprenoids, and (c) nitrogen or sulfur containing compounds, and their principal biosynthetic pathways and their regulation in stone fruit. Then, the type and levels of bioactive compounds in different stone fruits of the Rosaceae family such as peach (Prunus persica), plum (P. domestica, P. salicina and P. cerasifera), sweet cherries (P. avium), almond kernels (P. dulcis, syn. P. amygdalus), and apricot (P. armeniaca) are presented. The last part of this review encompasses pre- and postharvest treatments affecting the phytochemical composition in stone fruit. Appropriate management of these factors during pre- and postharvest handling, along with further characterization of phytochemicals and the regulation of their synthesis in different cultivars, could help to increase the levels of these compounds, leading to the future improvement of stone fruit not only to enhance organoleptic characteristics but also to benefit human health.
... We focused our attention on almond skins. Unfortunately, the compounds like polyphenols responsible for the almond skins' bioactivity [3][4][5] undergo oxidation/degradation phenomena and are poorly soluble in water. When administered per os, these factors limit the in vivo bioavailability and bioactivity due to the slow dissolution rate in biological fluids. ...
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Background: Almond skins are rich in bioactive compounds that undergo oxidation/degradation phenomena and are poorly soluble in water, reducing in vivo absorption and bioavailability, factors that influence the pharmacological activity of an active product. We developed a dried acetonic almond skins extract/cyclodextrin complex to improve extract solubility, dissolution rate and biological activity. Methods: A lyophilized acetonic almond skin extract was produced. To optimize complex formulation, phase solubility studies and complex characterization (absorption studies, differential scanning calorimetry (DSC), morphology, solubility studies) were performed. To evaluate a possible use in healthy products, tumor necrosis factor-α levels and reactive oxygen species release, as well as cicloxygenase-2 and inducible nitric oxide synthase expression in intestinal epithelial cells, were also evaluated. Results: Phase solubility studies showed a Bs-type profile. A 1:1 dried acetonic almond skins extract/cyclodextrin ratio was able to improve extract water solubility and dissolution rate (100% in 45 min). The UV-Vis spectra of complex revealed a hypsochromic and hyperchromic effect, probably due to a partial inclusion of extract in cyclodextrin cavity through weak bonds, confirmed by DSC and morphology studies. The technological improvement in the extract characteristics also led to better biological activity. In fact, the complex effectively reduces tumor necrosis factor-α levels with respect to the pure extract and significantly inhibits the reactive oxygen species release, even if only at the lower concentration of 5 μg/mL. Conclusion: The complex was able to overcome solubility problems and could be used in inflammatory disease.
... Almond green hull as a potent source of natural antioxidants because it contains large amounts of phenolics and flavonoids (Milbury et al. 2006). Almond polyphenols are mostly found in the hull (Garrido et al. 2008). Almond hulls can limit the risk of various oxidative associated diseases (Meshkini 2016). ...
Article
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In Turkey, almonds are grown via the following three methods: organic (O), conventional (C) and good agricultural practice (GAP). Almond seeds are mostly consumed as nuts; thus, the researchers have focused different analyses on only seeds. However, in Turkey, unripe green almond hulls are also consumed. Therefore, we studied the contents of some bioactive components, pigments, and malondialdehyde (MDA) and the antimicrobial, antioxidant, and antimutagenic activities of O, C, and GAP 'Ferradual' (Frd) and 'Ferragnes' (Frg) almond hull extracts. The highest total ascorbic acid content was found in O Frd (2.1 mg/g fresh weight [FW]) and GAP Frg (2.0 mg/g FW). The total phenolic content and total flavonoid content in all the genotypes ranged from 19.2 and 43.9 mg/g FW and 3.2 and 20.2 mg/g FW, respectively. In general, the antioxidant activity of C Frg and C Frd was low. C Frg had the highest MDA content (8.53 µmol MDA/g FW), whereas O Frg had the lowest MDA content (0.89 µmol MDA/g FW). The samples had varying ratios of chlorophyll a and b. The O samples had more total carotenoid content than the C samples. The antibacterial activity was only observed in the O and GAP Frd extracts. The antifungal activity could not be detected in any of the extracts of samples. Varying antimutagenic activity in Salmonella typhimurium TA 98 strain and content of some phenolics were observed depending on the variety, growing conditions, and dose.
... Almond green hull as a potent source of natural antioxidants because it contains large amounts of phenolics and flavonoids (Milbury et al. 2006). Almond polyphenols are mostly found in the hull (Garrido et al. 2008). Almond hulls can limit the risk of various oxidative associated diseases (Meshkini 2016). ...
... However, some water-soluble substances may be transferred to the peeling and debitterizing water during the previous two steps such as protein, amygdalin, and phenolic compounds, thus causing great loss of nutritional compounds and weights for the apricot kernels, simultaneously bringing about the environmental problems with the water directly discharged (Abud, Maiella, Nicodemi, Pettorino, & Yoshida, 2013;Garrido, Monagas, Gómez-Cordovés, & Bartolomé, 2008). According to our survey conducted in factories, the total losing rate is about 25% of its gross weight after the aforementioned two procedures. ...
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The compositions and antioxidant capacity were investigated about the by-products (blanching water concentrate (BWC) and debitterizing water concentrate DWC) produced during the industrial processing of apricot kernels, to evaluate the by-products’ potential utilization. The results indicate that the by-products contain a great number of compounds like amygdalin, protein, phenolics, and flavonoids. Among them, the amygdalin has the highest content both in BWC and DWC, which is 33.48 ± 0.04 and 23.89 ± 0.03 (g/100 g dry base weight), respectively. Furthermore, the by-products exert good antioxidant functions including the higher reducing power and radical-scavenging capacity on the 2,2-Diphenyl-1-Picrylhydrazyl (DPPH) and hydroxyl radicals, which is mainly attributed to the phenolic compounds, not the highest content of amygdalin by the principal component analysis and verification test of DPPH radical-scavenging capacity. In conclusion, the by-products definitely have great potential for utilization and should be recycled from the wastewater in the apricot kernels processing industry, especially for amygdalin.
... However, roasted nuts have had 14% more total polyphenols than raw nuts and the percent of free polyphenols decreased [23]. Moreover, studies on almonds and hazelnuts showed an increment in antioxidant activity as an effect of roasting [24,25]. Nuts' antioxidant capacities were evaluated by the DPPH radical scavenging method, which is based on the measurement of the reduction ability of antioxidants towards the radical DPPH [26]. ...
Article
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The aim is to evaluate the effects of frying and roasting on nuts. Frying and roasting were performed according to the local Jordanian home-made cuisine, and the nuts under experiment were raw almonds, pine, cashew, and pistachio. Nuts samples were roasted at 110°C for 16 minutes and fried at 175°C for 2.5 minutes. The results show that both roasting and frying of nuts did not affect the flavonoids content except for roasted pistachios where significant rise of flavonoids content was detected. Total phenolic content showed no significant differences except for pine nuts in which it increased significantly in both roasting and frying. Oxidative stability, presented by 1,1-diphenyl-2-picryl-hydrazyl (DPPH), was significantly different in all nuts except for pistachio nuts that have shown no differences. Fatty acids profile, presented by saturated fatty acids (SFA), oleic acid (OL), and essential fatty acids (EFA), was affected significantly by roasting and frying, especially for SFA in almonds and pine nuts and α -linoleic acid (ALA) contents of pine. In conclusion, the effects of roasting and frying on the aforementioned nuts species were positive for fatty acids profile and antioxidants activity.
... (Garrido, Monagas, Gómez-Cordovés, & Bartolomé, 2008). ...
Article
Inflammatory bowel diseases (IBD) are illnesses characterized by chronic intestinal inflammation and microbial dysbiosis that have emerged as a public health challenge worldwide. It comprises two main conditions: Crohn's disease and ulcerative colitis. Currently, conventional therapy to treat IBD are not free from side effects, such as liver and kidney toxicity, drug resistance, and allergic reactions. In view of this, there is growing research for alternative and complementary therapies that, in addition to acting in the prevention or the control of the disease, do not compromise the quality of life and health of individuals. In this sense, a growing body of evidence has confirmed the benefits of natural phenolic compounds in intestinal health. Phenolic compounds or polyphenols are molecules widely distributed throughout the plant kingdom (flowers, vegetables, leaves, and fruits), including plant materials remaining of the handling and food industrial processing, referred to in the scientific literature as by-products, food waste, or bagasse. Since by-products are low-cost, abundant, easily accessible, safe, and rich in bioactive compounds, it becomes an exciting option to extract, concentrate or isolate phenolic compounds to be posteriorly applied in the therapeutic approach of IBD. In this article, we have reviewed the main phenolic compounds present in various plants and by-products that have shown beneficial and/or promising effects in experimental pre-clinical, clinical, and in vitro research with IBD. In addition, we have mentioned and suggested several plants and by-products originated and produced in Latin America that could be part of future research as good sources of specific phenolic compounds to be applied in the prevention and development of alternative treatments for IBD. This review may offer a valuable reference for studies related to IBD administering phenolic compounds from natural, cheap, and easily accessible raw and undervalued materials.
... Third, it is suggested that nut components other than fatty acids, such as vitamins (e.g., vitamin E, vitamin B6, niacin, and folic acid), minerals (e.g., magnesium, potassium, and copper), dietary fiber, plant protein (e.g., arginine), phytosterols, and phenolic antioxidants are also bioactive in lowering serum TC level (104). Recent evidence suggests that the phytosterols in nuts which are more hydrophobic than cholesterol, impair cholesterol absorption because their hydrocarbon molecule is larger and has a greater affinity for micelles than cholesterol (105). As a result, cholesterol is displaced from the micelles, and the amount available for absorption becomes more limited (106). ...
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Background Nuts are in the spotlight because of their association with improved health outcomes. We aimed to summarize the findings of previous studies to evaluate the impact of nuts consumption on glycaemic and lipid profile, inflammation, and oxidative stress. Methods Electronic searches for observational and intervention studies were undertaken in PubMed, Embase, Web of Science, and Science Direct until 2022 for searching the studies aiming the application of different types of nuts and the beneficial effects of nuts in improving glycemia, dyslipidemia, inflammation, and oxidative stress. Results Results from 56 interventional, 9 narrative and 3 systematic reviews, and 12 meta-analysis studies, aiming at the evaluating beneficial effects of different types of nuts on metabolic markers, showed that nut consumption could improve metabolic markers, including glycaemic factors, lipid profile, and inflammatory and oxidative stress parameters in both healthy and individuals with metabolic disorders in a type-, dose- and duration-dependent manner. According to their unique nutrient components, nuts can be known as a part of a healthy diet, resulting in improved metabolic biomarkers. Conclusion Considering the efficacy of nuts in improving metabolic markers, incorporation of, incorporating nuts the effectiveness of nuts in improving metabolic markers, incorporating nuts in the diet may prevent the incidence or aggravation of chronic metabolic diseases. Considering the health benefits of the nuts' components, including essential micronutrients, if consumed in the appropriate dose and duration to provide the necessary amount of effective micronutrients to improve health, we will see an improvement in metabolic factors. At the same time, more research is required to determine the optimal type, dose, and duration of nut intervention with regards to metabolic control and reducing the risk of developing metabolic disorders.
... [7] Roasting, however, has a detrimental effect on bioavailability by increasing the content of phytic acid and tannins and reducing antioxidant activity. This is contrary to some study, [71] which claims roasting has a positive effect on the antioxidant capacity of nut extract compared with blanching and drying. In addition, two clinical studies investigated the effect of roasting on the allergenicity of hazelnuts through double-blind placebo-controlled food challenges (DBPCFCs). ...
Article
The global consumption of nuts is steadily increasing in recent years. Tree nuts have many beneficial physiological functions because of the presence of diverse range of phytochemicals. However, nuts also contain some anti-nutritional compounds, such as birch pollen and phytic acid, negatively affecting bioavailability of nut. Total phenolic content and antioxidant ability of some tree nuts can be enhanced with thermal processing. Some novel non-thermal pasteurization applications in nuts processing industries can strengthen the bioaccessibility and bioavailability by reducing the antinutri-tional compounds and decreasing the allergenic protein solubility. The current review summarized the bioaccessibility of some typical phytochemicals in nuts and general impact of processing on them. The processing for nuts emphasis on the common means (roasting, peeling, etc.) and some novel treatments (e.g. pulsed electric field). In addition, the bioavailability of those phytochemicals mentioned in this review.
... Moreover, although the acetone showed a total phenol content similar to that obtained by ethanol, it also showed the lowest yield (Figure 3); this effect could be related to the high volatility of the acetone with respect to other solvents. Finally, the values of the total phenol content of the almond shell found in this research are lower than those reported in P. dulcis (21,22,35,36), P. amygdalus (33,37), and P. serotina Ehrh (7). However, they are similar to those reported by Moure et al. (24) in P. amygdalus and Bolling et al. (38) in California almonds. ...
Article
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The Capulin almond is a seed of the Prunus serotina (var. capuli) that belongs to the Rosaceae family. In this study, the valorization of the Capulin almond was performed by extracting antioxidants contained in the shell, paste, and oil (extracted by manual cold pressing process) of Prunus serotina treated with methanol, ethanol, acetone, and acidified water (pH 4) in a ratio of 1:5 (w/v). Total phenols were performed using the Folin-Ciocalteu method and expressed as gallic acid equivalents (GAE), antioxidant activity was determined by ABTS and DPPH methods and expressed as Trolox equivalents (TE). Finally, the total flavonoids were determined using a catechin calibration curve and reported as catechin equivalents (CE). The highest extraction of total phenols in shell was obtained with methanol (1.65 mg GAE/g sample) and the lowest using acidified water (0.97 mg GAE/g sample). However, extraction with acidified water favored this process in the paste (1.42 mg GAE/g sample), while the use of solvents did not influence it significantly (0.72 to 0.79 mg GAE/g sample). Regarding the total flavonoids, the values for the shell, paste, and oil were of 0.37, 0.78, and 0.34 mg CE/g sample, respectively, while that corresponding to the antioxidant activity evaluated with ABTS and DPPH were of 1527.78, 1229.17, 18894.44 μM TE/g, and, 568.45, 562.5 and 4369.05 mM TE/g sample, respectively. Finally, our results suggest that by-products such as the shell, paste, and oil obtained from Prunus serotina (var. capuli) represent a potential alternative for the recovery of bioactive compounds with antioxidant activity such as phenolic compounds and flavonoids.
... Reports suggest that even though almond skins have only 4% total almond weight, they have a significant portion of around 70-100% polyphenols and other phenolic compounds and are therefore highly enriched in antioxidants. 13,14 Therefore, almond shell waste was used for biochar preparation in this work, and antioxidants were extracted from blanched almond skin waste. ...
Article
A strategic modification involving (i) a multi-functional almond shell biochar surface support and (ii) capping with almond skin extracted antioxidants was performed to preserve redox-sensitive Fe0 nanoparticles (NPs). pXRD data showed generation of an iron-carbonyl shell on the supported Fe0 NPs (SA-Fe0), justifying successful antioxidant capping. The total metal removal capacity of 695 mg g-1 i.e. AsO2- (300.2 mg g-1) > Cd2+ (224.2 mg g-1) > CrO42- (125.2 mg g-1) > Ni2+ (44.5 mg g-1) in batch mode, and 102 mg g-1 in continuous column setup confirms the excellent reactivity of the SA-Fe0 nanocomposite. Loss of the iron-carbonyl shell and iron oxidation during interaction with contaminants confirm no hindrance in electron transfer due to antioxidant capping.
... It has been shown that the roasting procedure could enhance total phenolics and the contents of some phenolics such as protocatechuic acid and catechin in roasted pistachios (single-roasted or double-roasted), which were significantly higher than in raw pistachios [41]. This may be due to heat processing promoting the release of phenolics [42,43]. At the same time, the differences between components may not be shown by regular chemical assays, which cannot mimic the complexity of biological systems; however, these activities could be detected by more physiologically relevant assays such as the CAA assay and antiproliferative activity assay. ...
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The consumption of pistachios has been linked to many potential health benefits. Phytochemicals in pistachios, including phenolics, vitamin E and carotenoids, have been considered to make contributions to the health benefits. The objectives of this study were (1) to explore the phytochemical profiles (total phenolics and total flavonoids, including both free and bound forms), selected phytochemicals, vitamin E and carotenoids of raw and roasted pistachios; (2) to determine total antioxidant activity and cellular antioxidant activity (CAA); and (3) to explore antiproliferative activities of pistachio extracts against human breast, liver and colon cancer cells in vitro. Both raw and roasted pistachios contained high total phenolics, at 479.9 ± 10.2 (raw) and 447.9 ± 9.4 (roasted) mg GAE/100 g, respectively, and high flavonoids, at 178.4 ± 10.6 (raw) and 144.1 ± 7.4 (roasted) mg GAE/100 g, respectively. The contributions of the free form to the total phenolics in pistachios were 82% (raw) and 84% (roasted), respectively, and the contributions of the free form to the total flavonoids in pistachios were 65% (raw) and 70% (roasted), respectively. Gentisic acid and catechin were the major phenolics in raw and roasted pistachios, respectively. Both raw and roasted pistachios had similar total antioxidant activity evaluated by Oxygen-Radical-Scavenging Capacity (ORAC) assay, at 7387.9 ± 467 (raw) and 7375.3 ± 602 (roasted) μmol TE/100 g, respectively. Both raw and roasted pistachio extracts exhibited cellular antioxidant activity inhibiting peroxyradical radical-induced oxidation, with CAA values of 77.39 ± 4.25 (wash) and 253.71 ± 19.18 (no wash) μmol QE/100 g of raw pistachios and 115.62 ± 3.02 (wash) and 216.76 ± 6.6 (no wash) μmol QE/100 g of roasted pistachios. Roasted pistachios contained more vitamin E when compared with raw pistachios, while raw pistachios contained more carotenoids than the roasted pistachios. Additionally, the free form of roasted pistachios extracts exhibited superior antiproliferation activity against HepG2, Caco-2 and MDA-MB-231 cancer cells in a dose-dependent manner, with EC50 34.73 ± 1.64, 36.66 ± 3.3 and 7.41 ± 0.82 mg per mL, respectively. These results provided new knowledge about the phytochemical profiles, antioxidant activity, cellular antioxidant activity and antiproliferative activity of raw and roasted pistachios.
... Harvested drupes enter a first stage of hulling, in which the external coating is removed, forming almond hulls that accounts for the 52% of total produced mass; then, shelled almonds are subjected to shell removal, obtaining the coated almond kernels separated from shells, that represent the 33% of the total fruit. Finally, kernels, which constitutes the 11% of the original almond fruits, are blanched in order to eliminate the skins (which represents the 4%) by a treatment with hot water followed by a final peeling step [7,8]. As a result, four main by-products have gained much attention in the sector of almond production ( Figure 1): almond hulls (AHs), almond shells (ASHs), almond skins (ASKs), and blanching water (BW). ...
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The search for waste minimization and the valorization of by-products are key to good manage-ment and improved sustainability in the food industry. The great production of almonds, based on their high nutritional value as food, especially almond kernels, generates tons of waste yearly. The remaining parts (skin, shell, hulls, etc.) are still little explored, even though they have been used as fuel by burning or as livestock feed. The interest in these by-products has been increasing, as they possess beneficial properties, caused by the presence of different bioactive compounds, and can be used as promising sources of new ingredients for the food, cosmetic and pharmaceutical industry. Additionally, the use of almond by-products is being increasingly applied for the fortification of already-existing food products, but there are some limitations, including the presence of allergens and mycotoxins that harden their applicability. This review focuses on the extraction technologies applied to the valorization of almond by-products for the development of new value-added products that would contribute to the reduction of environmental impact and an improvement in the sustainability and competitiveness of the almond industry.
... Almond skin is also rich in phenolic compounds, such as (+)-catechin, (−)-epicatechin, naringenin-7-O-glucoside, kaempferol-3-O-rutinoside, isorhamnetin-3-O-rutinoside, isorhamnetin-3-O-glucoside, and naringenin. The flavonoids present are isorhamnetin, isorhamnetin-3-O-glucoside, kaempferol, quercetin-3-galactoside, catechin, kaempferol-3-Oglucoside, kaempferol-3-O-galactoside, and quercetin [110,116]. Also, some alcohols (1butanol, 1-hetanol, 1-hexanol, 1-nonanol, 1-octanol, 1-pentanol, 1,2-propanediol, 2-ethyl-1-hexano, 2-heptanone, 2-methyl-1-propanol, 2-phenylethanol, 3-methyl-1-butanol, 3-methyl-2-buten-1-ol, 3-methyl-3-buten-1-ol, and benzyl alcohol), acids (acetic and hexanoic acids), pyrazine (2-methylpyrazine), terpene (α-pinene and limonene), lactone (butyrolactone), alkane (toluene), and aldehydes (benzaldehyde, heptanal, hexanal, nonanal, octanal, and pentanal) have been described being present in raw almonds [117,118]. Squalene is also present in almonds (95.0 mg/kg) [114]. ...
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... 46 Several phenolic compounds, including flavan-3-ols, flavanol glycosides, hydroxybenzoic acids, and aldehydes, are generally extracted from almond skins, which show antioxidant properties. 47 All of these antioxidants can cover and cap the iron nanoparticles, helping in preserving their redox nature and reactivity for contaminants. ...
... Almond skin is regarded as a potential functional food due to its high antioxidant polyphenol, prebiotic fibres and probiotic index . It can be used as additives in food industries to lower lipid peroxidation as well as functional ingredient in dietary supplements (Garrido et al. 2008). ...
Chapter
The food industry is generating huge amounts of by-products, about 1,890,000 tons, which should be better recycled into pharmaceuticals, cosmetics and functional foods, for instance, in order to save costs and avoid pollution. Here we review food by-products and methods of extraction. We present bioactive compounds from fruits, vegetable, tea, coffee, egg, nuts, meat and dairy products. Extracting methods include soxhlet, maceration, microwave, ultrasound, pressure.KeywordsFood by-productsBioactive moleculesNovel techniquesConventional techniquesGreen techniquesEnvironmental pollution
... Almond skin is regarded as a potential functional food due to its high antioxidant polyphenol, prebiotic fibres and probiotic index . It can be used as additives in food industries to lower lipid peroxidation as well as functional ingredient in dietary supplements (Garrido et al. 2008). ...
Chapter
The food industry is generating huge amounts of by-products, about 1,890,000 tons, which should be better recycled into pharmaceuticals, cosmetics and functional foods, for instance, in order to save costs and avoid pollution. Here we review food by-products and methods of extraction. We present bioactive compounds from fruits, vegetable, tea, coffee, egg, nuts, meat and dairy products. Extracting methods include soxhlet, maceration, microwave, ultrasound, pressure.
... Then, ORAC assay, which is more sensible (specially for lipidic compounds), can be affected by these changes. These results are in the same range to those obtained by Garrido et al. (2008), who studied the effect of the industrial processing on the antioxidant activity of American and Spanish almond skins. These authors reported ORAC values ranging from 33.1 up to 108 mmol TE/100 g, obtaining the highest values for the roasted samples, compared to blanched ones. ...
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Almonds are considered one of the most valuable fruits worldwide due to its high nutritional value. Moreover, a growing attention has been paid over the last years to other parts of the fruit, such as skins, shells or hulls, which are commonly found as almond by-products and scarcely exploited for valorization. In this study, two approaches were evaluated. Firstly, a green innovative processing technology, pulsed electric fields (PEF), was applied for the first time to assist the extraction of antioxidant compounds from almond hull biomass (AH). In particular, this technology was used with the aim of developing a feasible valorization strategy, being a sustainable alternative for polyphenols extraction compared to traditional methods. Then, the total phenolic content (TPC) and the antioxidant activity (TEAC and ORAC values) were measured, obtaining a higher extraction of TPC and TEAC values when PEF was used compared to conventional soaking. Secondly, the characterization of AH by means of fiber, ultimate and proximate analysis was carried out. Ultimate and proximate analysis provided information about the exploitation towards bioenergy and biofuels, demonstrating the so-called derived AH-EFB being useful for that purpose. Moreover, the high percentage in terms of carbohydrates suggests that AH could be a useful source for high-added-value chemicals, such as levulinic acid, furfural and 5-hidroximethylfurfural, displaying an interesting energetic valorization route for this biomass.
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Almond is one of the most commonly consumed nuts worldwide, with health benefits associated with availability of bioactive compounds and fatty acids. Almond is often eaten raw or after some processing steps. However, the latter can positively or negatively influence chemical and sensorial attributes of almonds. This work was carried out to assess the effects of two processing treatments, namely; roasting and blanching on (i) contents of bioactive compounds, (ii) contents of fatty acids (3) antioxidant activities (4), sensorial characteristics of four neglected Portuguese almond cultivars (Casanova, Molar, Pegarinhos and Refêgo) and two foreign cultivars (Ferragnès and Glorieta). Results showed that in general, levels of bioactive compounds and antioxidant activities increased with roasting and decreased with blanching. Fatty acid profiles of raw kernels of all cultivars were generally identical although Refêgo exhibited a high content of α-linolenic acid. Following roasting and blanching, content of polyunsaturated fatty acids increased while saturated fatty acids, monounsaturated fatty acids and several health lipid indices decreased. Roasting positively affected perception of skin color and sweetness of Ferragnès and Glorieta as well as skin roughness of Molar and Pegarinhos. Blanching on the other hand led to positive changes in textural properties of Refêgo and Pegarinhos. This study reveals the nutritive benefits of consuming neglected almond cultivars in Portugal, and the novel data reported here could be of interest to growers, processing companies and consumers.
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The aim of this study is to compare the impact of methane sulphonic and sulfuric acid hydrolysis for xylose recovery from almond industry waste such as shell (ASH) and skin (ASK). A two stage dilute acid hydrolysis (<1 % w/w) was evaluated to improve xylose following arabinose removal in stage 1. Sulfuric acid was observed to yield higher xylose- ASK (3.88 g/L) and ASK (14.01 g/L). Though xylose recovery was lower (38.1 % in ASH and 31.7 % in ASK) with methane sulphonic acid the hydrolyzed fibers showed enhanced delignification resulting in separation of the individual fibers suitable for downstream application in fiber composites. FTIR studies indicate an increased loss of syringyl subunit of lignin along with changes in core lignin structure with methane sulphonic acid responsible for fiber separation.
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Background An increasing number of people are electing to consume dairy free products owing to factors such as a vegan lifestyle, and health reasons. Evidence suggests that consumption of foods containing prebiotics and probiotics are on the rise. Tree nuts are a group of nuts that are dense in nutrients and have pleasant organoleptic properties. Tree nuts are traditionally consumed as is or made into confectionaries. Scope and approach A literature survey was conducted to understand properties of tree nuts. Searches on tree nuts with relation to prebiotics, probiotic, and synbiotic products were also done. The production strategies, properties, and bacterial strains used, for tree nut based prebiotics, probiotic beverages, yogurt alternatives, and, powders were critically evaluated. The properties of tree nut based probiotic products were compared to their dairy counterparts, in order to assess the challenges, differences, and, similarities involved. Key findings and conclusions Parts of tree nuts such as kernel, skin, and, hull are potential sources of prebiotics. Tree nuts are amenable to the production of dairy free probiotic products; but are faced with challenges, such as, low physical stability, poor strain viability and, lack of sensory acceptance. The paper concludes that synbiotic products could be made from tree nut based prebiotics, but more research needs to be done to confirm this. The review suggests that tactics such as microencapsulation, micro fluidization, addition of stabilizing gums, and, meeting all the bacterial strain selection criteria, can be used to solve the challenges faced by the tree nut based probiotic products.
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The polyphenols profiles of the methanol extracts of bitter apricot [Armeniaca Sibirica (L.)]kernel skins (AKS)were analysed by liquid chromatography-electrospray ionization mass spectrometry. The antioxidan, anticancer effect on HepG2 cell and antibacterial properties of the AKS polyphenol extracts were further characterized in vitro. Polyphenol compounds (35), including nine phenolic acids, thirteen anthocyanins and thirteen flavonoids, were identified in AKS for the first time. The content of apigenin 7-O-glucoside, (cyanidin 3-(4″-acetylrutinoside), 3- (6″-acetylglucoside)-5-glucoside and salicylic acid was relatively high than the others. The AKS polyphenols strongly reduced Fe ³⁺ and exhibited good scavenging activity towards 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid)free radicals, 1,1-diphenyl-1-picrylhydrazyl free radicals, hydroxyl radicals, superoxide anions and hydrogen peroxide. The AKS polyphenols could regulate oxidant stress in HepG2 cells by downregulating reduced glutathione, upregulating oxidative glutathione, malondialdehyde and advanced oxidation protein products, and reduced cell viability to induce apoptosis of HepG2 cells in vitro. The AKS polyphenols showed strong antibacterial activity against Escherichia coli, Staphylococcus aureus, Bacillus subtilis, Acetobacter aceti and Bacillus cereus. Therefore, the antioxidant, inhibitory effect on HepG2 cells and antimicrobial activity of the AKS polyphenols were distinct and worthy of further consideration for medical industry applications.
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Tree nuts and related seeds such as peanuts and oilseeds contain large numbers of secondary metabolites. These compounds have beneficial qualities for human health and wellness, but the reports on them are scattered. The growing field of metabolomics aims to characterize these compounds in a systematic way so that the mechanism of their formation can be better understood. This review gathers current studies using both targeted and non‐targeted approaches to the analysis of secondary metabolites from tree nuts and related oilseeds. Almonds, Brazil nuts, hazelnuts, macadamia nuts, pecan, pine nuts, pistachios, walnuts, peanuts, rapeseeds, and sesame seeds are included along with some lesser known products. The changes with roasting are also discussed. Phenotypic data of this type is useful for identifying specific genetic markers that could be used for crop improvement. High value crops such as tree nuts, peanuts and oilseeds would benefit from these advances in the understanding of the development of secondary metabolites as they are crucial to seed development, growth, and characteristic flavors. Practical Applications: Tree nuts and seeds are sources of high quality protein and oils worldwide. This review gathers information about more recent studies of the secondary metabolites that are present in these products. The identification and understanding of their mechanism of their formation is needed for expanding the role of tree nuts and related seeds in nutrition and health. A critical review allows for the collection of research in this topic to increase access of the results to those in the field who continue to advance these studies.
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The objective of this research was to quantify the concentration levels of the cyanogenic compounds, amygdalin and prunasin present in some varieties of almonds, considering their conversion to hydrocyanic acid, and their possible consumption in addition to other industrial uses, seeds of 29 commercial varieties were used of almond (Prunus dulcis Miller), evaluating its concentration and toxicity levels, taking into account the minimum degree of theoretical intake both for human consumption and for animals, through feed, this in terms of by-products. In addition, thermophysical properties thermophysical properties (thermal conductivity, thermal diffusivity, specific heat and density) and industrial uses were determined. The concentration was determined by chromatographic techniques (HPLC) and colorimetry (microdiffusion). The results obtained showed low levels of amygdalin from "not detected" to 375.40 mg/100 g of sample, depending on the sweet, slightly bitter and bitter varieties. The results indicate its possibility of commercialization, uses and applications in the food and pharmaceutical industry.
Chapter
Almond (Prunus dulcis) is a drupe, belongs to Rosaceae family, ranked one in the production of tree nut worldwide, majorly from the United States (~80%). Typically, five major varieties are grown in United States, which include Mission, Nonpareil, California, Peerless and Neplus Ultra. There are four major portions: hull, shell, brown leathery skin and kernel. The edible kernel is majorly utilized as snack or as an ingredient in bakery and confectionary products and by-products are fed to livestock. Nuts are rich in protein, lipid, dietary fibre, vitamins and minerals. Besides almond, kernel also encompasses bioactive compounds like phenolic compounds, tocopherols, sterols and resveratrol. Many researchers identified that by-products of almond processing industry are the potential source of anti-disease or phytochemicals, especially brown leathery skin of almond (~95%). These bioactive compounds possess antioxidant activity with potential to decrease the oxidative DNA damage and lipid oxidation leading to the prevention of degenerative diseases like coronary heart diseases (CHD), cholesterol lowering, diabetes and cancer. Therefore, almond and its by-products can potentially be utilized as an alternative to synthetic chemical or as dietary supplement or as a functional food ingredient in the development of convenience or nutraceutical food.
Chapter
The global agriculture industry produces tens of millions of plant waste every year, which environmental issues, yet plant waste is rich in phytochemicals with various health benefits. Here we review plant and food waste as a source of therapeutic compounds with focus on phytochemicals and food by-products. Phytochemicals include phenolics, alkaloids and terpenids. Food by-products include compounds from tomato, carrot, onion, potato, pumpkin, maize, paddy, asparagus, cocoa, tea, coffee, buckwheat, almond, walnut, pistachio, cashew nut, hazelnut, and peanut. Medicinal properties include anticance, antimicrobial, anti-inflammatory, anti-viral, antiproliferative, and treating hyperglycaemia, hypercholesterolemia and cardiovascular diseases.KeywordsBy-productsAgriculture wasteFruitsVegetableAgro-plantNutsAntioxidantAntimicrobialAnticancerAnti-hypercholesterolemia
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Almonds ( Prunus dulcis) are one of the most consumed tree-nuts worldwide, with commercial production in arid environments such as California, Spain, and Australia. The high consumption of almonds is partly due to their versatile usage in products such as gluten-free flour and dairy alternatives as well as them being a source of protein in vegetarian diets. They contain high concentrations of health-promoting compounds such as Vitamin E and have demonstrated benefits for reducing the risk of cardiovascular disease and improving vascular health. In addition, almonds are the least allergenic tree nut and contain minute quantities of cyanogenic glycosides. Production has increased significantly in the past two decades with 3.12 billion pounds of kernel meat produced in California alone in 2020 (USDA 2021), leading to a new emphasis on the valorization of the coproducts (e.g., hulls, shells, skins, and blanch water). This article presents a review of the chemical composition of almond kernels (e.g., macro and micronutrients, phenolic compounds, cyanogenic glycosides, and allergens) and the current research exploring the valorization of almond coproducts. Expected final online publication date for the Annual Review of Food Science and Technology, Volume 13 is March 2022. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.
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In this paper, the experiments were conducted to investigate the effects of saturated hot air (SHA) pretreatment on the components in apricot kernels and skins compared with the traditional blanching (TB) method, so as to evaluate the feasibility of SHA for removing the skins. Furthermore, the heatmap was employed to correlate the phenolic components and the color values. The results indicate that the SHA temperature and time had a definite influence on some of the components including phenols, amygdalin, proteins and reducing sugars. Compared with the TB, not only the loss of amygdalin, proteins and reducing sugars in apricot kernels used in SHA pretreatment greatly decreased, but also the loss of the phenols, flavonoids, protocatechin, catechin, vanillic acid and chlorogenic acid in the skins decreased by 42.3%, 50.5%, 57.8%, 63.3%, 94.5% and 42.5%, respectively. The SHA pretreatment for removing skins could decrease the amount of wastewater discharge, and lower the loss of active substances in apricot kernels and its skins. In conclusion, the SHA might be as a novel green and efficient method for removing the apricot kernel skins.
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In order to efficiently utilize the agricultural by-products, apricot kernel skins (AKS) and reduce the resource waste, the AKS was added to partially replace the wheat flour to develop the healthy bread in our preliminary study. In this paper, the effects of AKS addition and ultrasound irradiation on the quality properties of bread were investigated by the texture analyzer, confocal laser scanning microscope, electronic nose, tongue and gas chromatography-ion mobility spectrometry (GC-IMS), respectively. The results indicate that the addition of AKS had the negative effects on the microstructure of dough and the texture of fresh bread, but the ultrasonic treatment on the dough could significantly reduce the negative effects. Furthermore, AKS addition slowed the deterioration of the bread texture during chilled storage, and enriched the varieties of volatile organic compounds (VOCs) of bread. In a word, AKS could be employed in novel bread development so as to reduce the resource waste and environmental pollution.
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During the industrial processing of almond fruits, tons of almond skins are generated. Valorization of blanched almond skin wastes by recovering natural polyphenols using water, instead of organic solvents, for direct application of aqueous baths for dyeing of wool fabrics was studied in this work. The results showed that it was possible to recover polyphenols from almond skins and use them as a dye for wool fibres. Kinetics of extraction was modelled by using the diffusion-based Chrastil’s model and Peleg’s empirical model, obtaining excellent fit in both cases (R ² > 0.96). The amount of polyphenol extracted was enough to achieve correct direct dyeing with excellent washing, rubbing and perspiration fastness although the shades obtained were dull. Nevertheless, it was possible to achieve a better coloration by using ion(II) sulfate as the mordant resulting in dyeings with reasonable good washing and rubbing fastness.
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The present review deals with recently reported novel natural flavones and flavonols (mid-1999 to early 2004), along with various biological and pharmacological activities as exhibited by these important groups of flavonoids. The present resumé lists 252 new naturally occurring flavones and flavonols reported during the period. Natural distribution by plant family of the flavonoids is considered; a variety of plant species belonging to fifty-two different plant families is mentioned as their natural sources. Therapeutic efficacies of these constituents are also cited. The review covers 231 references.
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Antioxidant activities of ethanolic extracts of whole almond seed, brown skin, and green shell cover were evaluated using different free radical trapping assays. Trolox equivalent antioxidant capacity assay revealed that the total antioxidant capacities of brown skin and green shell cover extracts were 13 and 10 times greater than that of the whole seed extract at the same extract concentration. The free radical-scavenging activity of extracts of brown skin and green shell cover also exceeded that of the whole seed. The scavenging activity of superoxide radical by different almond extracts ranged from 76 to 97% at 100 ppm and 85 to 99% at 200 ppm. The corresponding reduction of hydrogen peroxide concentration was 59–66% (100 ppm) and 86–91% (200 ppm). The hydroxyl radical-scavenging capacities at 100 and 200 ppm were 16 and 42% for whole seed, 57 and 100% for brown skin, and 40 and 56% for green shell extracts, respectively. A 100% scavenging activity of the 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical was observed for brown skin and green shell extracts at 100 and 200 ppm concentrations, respectively, and whole seed extracts scavenged 21 (at 100 ppm) and 73% (at 200 ppm) of the DPPH radical.
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This study was carried out to evaluate the effect of heating and physical conditions of grape seeds on the antioxidant activity of their extracts. Two forms of grape seeds, whole and powdered forms, were heated at four different temperatures −50, 100, 150 and 200 °C. After heating, grape seeds were extracted with 70% ethanol (0.1 g grape seed/10 mL of 70% ethanol), and total phenol contents (TPC), radical scavenging activity (RSA) and reducing power of the extracts were determined. Thermal treatment of grape seed increased the antioxidant activity of extracts. The maximum TPC and RSA of whole grape seed extract (WGSE) were achieved when the seeds were heat-treated at 150 °C for 40 min, while that of powdered grape seed extract (PGSE) were at 100 °C for 10 min, and were greater than that of the non-treated control. Also, the reducing powers of WGSE and PGSE slightly increased at the conditions. According to the GC-MS analysis, several low-molecular-weight phenolic compounds such as azelaic acid, 3,4-dihydroxy benzoic acid, and o-cinnamic acid were newly formed in the WGSE heated at 150 °C for 40 min. There were slight differences in the kinds of phenolic compounds between non-heated and heated GSE. In HPLC analysis, the contents of gallocatechin gallate and caffeine in GSE significantly increased by heat treatment. These results indicated that antioxidant activity of GSE was affected by heating conditions (temperature and time) and physical conditions of grape seeds at the time of heat treatments.
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In this work, 8 different solvents/mixtures have been tested for the extraction of antioxidants from by-products derived from the industrial processing of almonds (skin or seed coating, brown hull, and green shell cover or mesocarp). The oxygen radical absorption capacity (ORAC) as well as the phenolics content of the extracts has been determined. The extracting solution methanol/HCl (1000:1, v/v) was the most effective for the almond skin and shell, whereas, for the hull, it corresponded to acetone/water (50:50, v/v), resulting in ORAC<sub>Fluorescein</sub> values of 0.467, 1.45 and 0.0504 mmol of Trolox/mg, respectively. At the same time, the mixtures acetone/water exhibited the highest content of total polyphenols and proanthocyanidins for the three by-products studied. Finally, results have shown that the by-products derived from almond processing, in particular, the skin and shell, posses a similar antioxidant capacity to that of grape by-products which are currently used in the development (or production) of antioxidant products. En este trabajo se han ensayado 8 disolventes/mezclas distintas para la extracción de antioxidantes a partir de los subproductos derivados del procesado industrial de la almendra (piel, cáscara y mesocarpio). Se ha determinado la capacidad de absorción de radicales oxígeno (ORAC) de los extractos, así como su contenido fenólico. La solución extractante metanol/HCl (1000:1, v/v) resultó más efectiva para la piel y el mesocarpio, mientras que para la cáscara lo fue la mezcla acetona/agua (50:50, v/v), dando lugar a valores ORAC<sub>Fluoresceína</sub> de 0,467, 1,45 y 0,0504 mmol de Trolox/mg, respectivamente. Por otro lado, las mezclas acetona/agua presentaron los valores más altos de polifenoles totales y proantocianidians para los tres subproductos ensayados. Finalmente, se concluye que los subproductos del procesado de la almendra, en particular, la piel y el mesocarpio, poseen una capacidad antioxidante similar a los subproductos de la uva actualmente empleados en la formulación de complementos antioxidantes.
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The ORAC-fluorescein (ORAC-FL) method recently validated using automatic liquid handling systems has now been adapted to manual handling and using a conventional fluorescence microplate reader. As calculated for Trolox, the precision of the method was <3.0, expressed as percent coefficient of variation. The accuracy of the method was <2.3, expressed as percent variation of the mean. The detection and quantification limits were those corresponding to 0.5- and 1-microM Trolox standard solutions, respectively. The method has been applied to 10 pure compounds (benzoic and cinnamic acids and aldehydes, flavonoids, and butylated hydroxyanisole), to 30 white, rose, and bottled- and oak-aged red wines, and to 7 commercial dietary antioxidant supplements. All samples exhibited a good linear response with concentration. As seen by other methodologies, the chemical structure of a compound determines its antioxidant activity (ORAC-FL value). Of particular interest were the results with oak-aged red wines from different vintages (1989-2002) that confirm influence of vintage, but not origin of the oak, in the antioxidant activity of wines from the same variety. Dietary antioxidant supplements presented a great variability (170-fold difference) in their antioxidant potency. This work proves applicability of the ORAC-FL assay in evaluating the antioxidant activity of diverse food samples.
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Consumption of tree nuts such as almonds has been associated with a reduced risk of coronary heart disease. Flavonoids, found predominantly in the skin of almonds, may contribute to their putative health benefit, but their bioactivity and bioavailability have not previously been studied. Almond skin flavonoids (ASF) were extracted with HCl:H2O:methanol (1:19:80) and their content of catechins and flavonols identified by HPLC with electrochemical detection. ASF bioactivity was assessed in vitro by their capacity to increase the resistance of human LDL to oxidation induced by 10 micromol/L Cu2+. ASF from 0.18 to 1.44 mumol gallic acid equivalent (GAE)/L increased the lag time to LDL oxidation in a dose-dependent manner (P < or = 0.0001). Combining ASF with vitamin E or ascorbic acid extended the lag time >200% of the expected additive value (P < or = 0.05). The bioavailability and in vivo antioxidant activity of 40 micromol ASF were examined in BioF1B hamsters. Peak plasma concentrations of catechin, epicatechin, and flavonols (quercetin, kaempferol, and isorhamnetin) occurred at 60, 120, and 180 min, respectively. The concentration of isorhamnetin was significantly elevated in liver at 180 min. Absorbed ASF enhanced the ex vivo resistance of hamster LDL collected at 60 min to oxidation by 18.0% (P = 0.028), and the in vitro addition of 5.5 micromol/L vitamin E synergistically extended the lag time of the 60-min sample by 52.5% (P < or = 0.05). Thus, ASF possess antioxidant capacity in vitro; they are bioavailable and act in synergy with vitamins C and E to protect LDL against oxidation in hamsters.
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In countries of the Mediterranean region, nuts have been consumed in moderate quantities since ancient times. Epidemiological studies show lower risk of cardiovascular diseases in populations with frequent nut consumption, independent from other dietary components. This article assesses nut consumption in Spain and other countries using different sources of data collected at the country, household or individual levels. The per capita consumption of nuts in Spain in 2001 was 7.9 g/person/d. The varieties most widely consumed are walnuts, almonds, hazelnuts and peanuts. Results of the eVe study estimate an average nut consumption in the Spanish population aged 25-60 years of 3.3 g/person/d. No significant statistical differences were observed between men and women. Consumption is higher in men aged between 35 and 44 years (4.5 g/d) and in women aged between 45 and 54 years (3.5 g/d). In the population of 2-24 years, according to the enKid study, nut consumption is estimated at 4.9 +/- 18.5 g/person per d. The age group with the highest consumption is teenagers between 14 and 17 years. The northeastern, northern and eastern regions of Spain show the highest consumption. According to FAO balance sheets, in 2001, Lebanon (16.5 kg/person per year) and Greece (11.9 kg/person per year) were the countries in the Mediterranean region with the highest consumption of nuts, followed by Spain (7.3 kg/person per year), Israel and Italy.
Article
In this work, the results of the gasification process of almond residues (almond shell, almond tree pruning, and almond shell peel) generated by an industry (PASAT SAT) are presented. This study was performed in a laboratory fixed-bed reactor. The objective was the obtaining of low/medium heating value gases, which could be burnt in a gas engine to generate electric energy. The effects of varying the air flow rate (50–400 cm3 min−1) and the temperature (650–800 °C) in the gasification process of the almond shell peel were discussed. An air flow rate of 200 cm3 min−1 and temperature of 800 °C were the optimal conditions with respect to the quality of the gas. At these conditions, the gasification processes of almond shell and almond tree pruning were also studied. The molar fractions of the fuel components reached their maximum values at these conditions with an average gas composition of 2.9% O2, 52.2% N2, 13.3% H2, 14.3% CO, 11.3% CO2, 4.8% CH4 and 1.2% C2H2, C2H4 and C2H6. The gas yield obtained was 1.66, 1.85 and 1.71 N m3/kg of residue for almond shell peel, almond shell and almond tree pruning, respectively. The higher heating value (HHV) of the gas obtained at these conditions (5.8, 6.5 and 6.4 MJ N m−3 for almond shell peel, almond shell and almond tree pruning, respectively) are comparable with the published data by other researchers. The carbon conversion was in the range between 81% and 90%. From the residues generated by the industry, with an average processing capacity of 1400 kg of residue/h, an energy potential of 3.99 MW thermal could be obtained. The design of a gasification plant for generation of electric energy with an alternator of 1.99 MW, considering a global efficiency of the process of 25%, could be performed.
Article
The effect of air-drying parameters on antioxidant activity and changes in antioxidant compounds of broccoli (Brassica oleracea L.) were studied. Broccoli samples were dried to 70 g kg−1 moisture content using temperatures ranging from 50 to 100 °C and air flow-rates from 1.20 to 2.25 m s−1, resulting in drying times from 25 to 90 min. Temperature, owing to its positive effect on the oxidation kinetics, was negatively correlated with ascorbic acid and free and total polyphenol contents but not with kaempferol, even though the sample dried at the highest temperature showed the lowest kaempferol content. The air flow-rate was positively correlated with the total (TPP) and free (FPP) polyphenol contents because it led to a reduction in the drying time. No correlation was found between air flow-rate and kaempferol content. Air flow-rate and temperature positively affected the antioxidant activity by reducing the drying time. High-temperature, short-time processes maximised the antioxidant activity of broccoli owing to the negative effect of drying time on antioxidant activity. The antioxidant activity of broccoli was positively and significantly correlated with the FPP content but not with TPP and kaempferol. The evaluation of hydroxymethylfurfural content as an indicator of the occurrence of a Maillard reaction in dried broccoli did not support the hypothesis of a contribution of MRPs to the antioxidant activity of dried broccoli. Copyright © 2006 Society of Chemical Industry
Article
Peanut skin was removed by direct peeling, blanching, and roasting. Total phenolics (TPs), total antioxidant activity (TAA) and free radical scavenging capacity of peanut skin extracts were determined. The composition of ethanolic extracts of peanut skin obtained from each processing method was determined by LC-MS and HPLC. Peanut skin processing methods significantly affected total extractable phenolics and their composition. Roasting had limited effects on concentration of TPs while blanching caused 89% loss of TPs. TPs in directly peeled, roasted, and blanched peanut skins were 130, 124, and 14.4 mg/g dry skin, respectively. Catechins, A-type and B-type procyanidin dimers, trimers and tetramers in chemically purified peanut skin extracts were identified by LC-MS. Total catechins, procyanidin dimers, trimers and tetramers in directly peeled peanut skin were 16.1, 111.3, 221.3 and 296.1 mg/100 g, respectively, versus 8.8, 143.5, 157.5 and 203.9 mg/100 g, respectively, in roasted dry skin. TAAs and free radical scavenging capacities of peanut skin extracts were all higher than those of Trolox and Vitamin C at equivalent concentration. Peanut skin, a by-product of the peanut processing industry, was found to contain potent antioxidants and could provide an inexpensive source of antioxidants for use as functional ingredients in foods or dietary supplements.
Article
An investigation of several agricultural wastes (almond shell, hazelnut shell, walnut shell and apricot stone) revealed that their suitability for granular activated carbon production is not determined by material specific (elemental composition) but type-specific features. Granular activated carbons were evaluated for their physical (attrition, bulk density), chemical (elemental composition, % weight loss), surface (surface area, surface chemistry) and adsorption properties (iodine number, phenol and methylene blue adsorption). Pyrolysis temperature and activation time with ZnCl2 had influence on the phenol and methylene blue adsorption capacities of especially for the activated carbons produced from hazelnut and walnut shells. Adsorption isotherm data were fitted to both Langmuir and Freundlich models. The following order of suitability of raw materials for activated carbon production was established: hazelnut shell > walnut shell ≈ apricot stone > almond shell.
Article
Almond (Prunus amygdalus) skins are agricultural by-products that are a source of phenolic compounds. Phenolic compounds from gamma-irradiated almond skins were extracted with 40% ethanol. Total phenolic content was determined using the Folin–Ciocalteu (F–C) method. Almond skin extracts (ASE): soybean oil (1:4 v/v) mixtures containing 0.08% FeCl3 were prepared. Antioxidant activity was determined by conjugated dienes and trienes (CD and CT, respectively) measurements, peroxide value (PV), Trolox® equivalent antioxidant capacity (TEAC) and Photochemiluminescence (PCL). Phenolic content yield (p < 0.05) was higher in ASE irradiated at doses greater than 4 kGy (trial I) or 12.7 kGy (trial II) compared to the control. Increased antioxidant activity was observed in TEAC assay and PCL with lipid-soluble antioxidant capacity reagents in ASE irradiated above 4 kGy (trial I) and 12.7 kGy (trial II) compared to 0 kGy. Gamma irradiation of almond skins thus increased the yield of total phenolic content as well as enhanced antioxidant activity of extracts.
Article
The antioxidant properties of peeled, defatted and roasted apricot kernel flours were evaluated by determining radical scavenging power (RSP), anti-lipid peroxidative activity (ALPA), reducing power (RP), total phenolic content (TPC), assessed by DPPH test, β-carotene bleaching method, iron (III to II) reducing test and Folin method, respectively. Browning degree of the samples was also measured and found to increase almost linearly with the roasting time. Contrary to browning degree, RSP, RP and TPC did not increase linearly but showed a maximum for 10 min of roasting. Roasting reduced the ALPA values, thus unroasted sample showed the highest ALPA value. RSP, RP and TPC measurements of all samples, were in high correlation (at least, r = 0.92).
The seed coat of almond (Prunus amygdalus Batsch) contains up to 30% procyanidins with different degrees of polymerisation and, in addition, fatty oils, lignin, polysaccharides and cutin. Monomer units of dimers to tetracosamers are (-)-epicatechin and (+)-catechin. Prodelphinidins could not be detected. The dimers B-1, B-3, B-4, trimers and oligomers are soluble in acetone/water. The bulk material is large polymer, that is only soluble, by thiolysis, in thioglycolic acid. The large polymer procyanidins are crucial to the structure and attributes of the seed coat.
Article
Food processing representatives, brokers, nutritionists, livestock producers, and trade associations were surveyed to quantify 9 by-products used for feeding livestock during 1992 in California. The commodities were almond hulls, dried beet pulp, wet brewers grains, wet citrus pulp, pressed citrus pulp, wet corn gluten feed, corn gluten meal, whole cottonseed, and rice bran. The 9 by-products contributed over 2.5 million tonnes and about 27% of the total feed concentrate moved within California during 1992. Market value of these 9 by-products was almost .25 billion dollars. Whole cottonseed accounted for about 31% of the total tonnage of these 9 by-products and provided about 66% of the total CP and 53% of the total NEL of these 9 by-products. The by-products were more valuable as energy sources than CP sources compared with NEL from corn and CP from soybean meal, respectively. Calculations of milk production, based on the CP content or NEL content of the by-products, showed that these 9 by-products could have contributed sufficient CP or NEL for over 31% of the milk produced in California during 1992. Ration formulations demonstrated that the economic value of by-products changed with feedstuffs available and, in general, would be used in rations over a range of market prices.
Article
Monomeric and oligomeric proanthocyanidins present in a range of plant-derived foods and beverages were separated by degree of polymerization and identified using a modified normal-phase high-performance liquid chromatography (HPLC) method coupled with on-line mass spectrometry (MS) analysis using an atmospheric pressure ionization electrospray chamber. In addition, ultraviolet (UV) and fluorescence detection were used to monitor the separation of proanthocyanidins, with fluorescence detection demonstrating both increased sensitivity and the ability to reduce interfering signals from other components present in the food and beverage matrices as compared to UV detection. This qualitative study demonstrates the ability of this HPLC/MS technique to separate singly and doubly linked procyanidins, prodelphinidins, and copolymer oligomers, including their galloylated derivatives, present in a range of food and beverage samples.
Article
Monomeric and oligomeric proanthocyanidins present in a range of plant-derived foods and beverages were separated by degree of polymerization and identified using a modified normal-phase high-performance liquid chromatography (HPLC) method coupled with on-line mass spectrometry (MS) analysis using an atmospheric pressure ionization electrospray chamber. In addition, ultraviolet (UV) and fluorescence detection were used to monitor the separation of proanthocyanidins, with fluorescence detection demonstrating both increased sensitivity and the ability to reduce interfering signals from other components present in the food and beverage matrices as compared to UV detection. This qualitative study demonstrates the ability of this HPLC/MS technique to separate singly and doubly linked procyanidins, prodelphinidins, and copolymer oligomers, including their galloylated derivatives, present in a range of food and beverage samples.
Article
Nine phenolic compounds were isolated from the ethyl acetate and n-butanol fractions of almond (Prunus amygdalus) skins. On the basis of NMR data, MS data, and comparison with the literature, these compounds were identified as 3'-O-methylquercetin 3-O-beta-D-glucopyranoside (1); 3'-O-methylquercetin 3-O-beta-D-galactopyranoside (2); 3'-O-methylquercetin 3-O-alpha-L-rhamnopyranosyl-(1-->6)-beta-D-glucopyranoside (3); kaempferol 3-O-alpha-L-rhamnopyranosyl-(1-->6)-beta-D-glucopyranoside (4); naringenin 7-O-beta-D-glucopyranoside (5); catechin (6); protocatechuic acid (7); vanillic acid (8); and p-hydroxybenzoic acid (9). All of these compounds have been isolated from almond skins for the first time. 2,2-Diphenyl-1-picrylhydrazyl (DPPH) free radical scavenging activities for compounds 1-9 were determined. Compounds 6 and 7 show very strong DPPH radical scavenging activity. Compounds 1-3, 5, 8, and 9 show strong activity, whereas compound 4 has very weak activity.
Article
Processed fruits and vegetables have been long considered to have lower nutritional value than the fresh produce due to the loss of vitamin C during processing. Vitamin C in apples has been found to contribute <0.4% of total antioxidant activity, indicating most of the activity comes from the natural combination of phytochemicals. This suggests that processed fruits and vegetables may retain their antioxidant activity despite the loss of vitamin C. Here it is shown that thermal processing at 115 degrees C for 25 min significantly elevated the total antioxidant activity of sweet corn by 44% and increased phytochemical content such as ferulic acid by 550% and total phenolics by 54%, although 25% vitamin C loss was observed. Processed sweet corn has increased antioxidant activity equivalent to 210 mg of vitamin C/100 g of corn compared to the remaining 3.2 mg of vitamin C in the sample that contributed only 1.5% of its total antioxidant activity. These findings do not support the notion that processed fruits and vegetables have lower nutritional value than fresh produce. This information may have a significant impact on consumers' food selection by increasing their consumption of fruits and vegetables to reduce the risk of chronic diseases.
Article
Prunes, which are industrially obtained by dehydrating fresh plums at 85-90 degrees C for 18 h, contain higher levels of phenolic compounds than most other fruits. Prune phenolics have shown beneficial effects on human health. Reports are available in the literature on ascorbic acid, phenol composition, and antioxidant activity of fresh plums and prunes, but there is a lack of publications on the influence of drying parameters on the phenolic compounds and antioxidant activity. A study was carried out on two plum cultivars using two sets of air-drying temperatures: (i) air temperature at 85 degrees C until 50% of prune moisture level and then the temperature was lowered to 70 degrees C; (ii) air temperature at 60 degrees C. Whole fresh and dried fruits were assessed for phenolics (catechins, hydroxycinnamic acids, anthocyanins, and flavonols), ascorbic acid, and antioxidant activity (all parameters were calculated on a dry matter basis). Analysis of data shows that chlorogenic and neochlorogenic acid changes were affected by both process parameters and cultivar. Drying destroyed anthocyanins, and there was a significant decrease in flavonols. Ascorbic acid was drastically reduced in relation to process temperature. The most striking result was that drying at 85 degrees C doubled antioxidant activity in both cultivars, while contradictory results were found for 60 degrees C processed plums.
Article
Seedcoats of 16 almond varieties were screened for flavonol glycosides by using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS). Flavonol glycosides were extracted by a simple methanolic extraction followed by a quick cleanup procedure with a Sep-Pak C(18) cartridge. Each of the 16 seedcoat samples exhibited a unique composition. Four flavonol glycosides, isorhamnetin rutinoside, isorhamnetin glucoside, kaempferol rutinoside, and kaempferol glucoside, were detected and quantified with use of rutin as an internal standard. Individual peak ratios were very consistent across triplicate analyses of all samples; the average standard deviation was 9%. In all almond varieties, isorhamnetin rutinoside was the most abundant flavonol glycoside, and the total content ranged from 75 to 250 microg/g.
Article
This paper reports an attempt to functionally and chemically characterize commercial ingredients from Vitis vinifera L. grape skins, grape pomace, and leaves, which are used in the formulation of dietary antioxidant supplements. The antioxidant capacity of these ingredients was assessed for the first time by the oxygen radical absorbance capacity (ORAC) methodology. Ingredients from grape skins and pomace (n = 17) showed ORAC values from 1.38 to 21.4 mumol Trolox equivalents/mg whereas ingredients from leaves (n = 4) showed ORAC values from 1.52 to 2.55 mumol Trolox equivalents/mg. The high-performance liquid chromatography-diode array detection/electrospray ionization-mass sprectrometry analysis of anthocyanins and flavonols revealed the authenticity of the ingredients as derived from V. vinifera L. and confirmed large differences in their phenolic content and distribution. A progressive decline in both antioxidant capacity and total anthocyanin content of a grape skin ingredient (43 and 40% decrease, respectively) was observed over a 60 day storage period (45 degrees C and 75% relative humidity), demonstrating its poor stability under these conditions.
Article
Antioxidant efficacy of defatted almond whole seed, brown skin, and green shell cover extracts was evaluated by monitoring inhibition of human low-density lipoprotein (LDL) oxidation, inhibition of DNA scission, and metal ion chelation activities. The total phenolic contents of ethanolic extracts of brown skin and green shell cover of almond were 10 and 9 times higher than that of the whole seed, respectively. Brown skin extract at 50 ppm effectively inhibited copper-induced oxidation of human LDL cholesterol compared to whole seed and green shell cover extracts, which reached the same level of efficacy at 200 ppm. Green shell cover extract at 50 ppm level completely arrested peroxyl radical-induced DNA scission, whereas 100 ppm of brown skin and whole seed extracts was required for similar efficiencies. All three almond extracts exhibited excellent metal ion chelation efficacies. High-performance liquid chromatographic (HPLC) analysis revealed the presence of quercetin, isorhamnetin, quercitrin, kaempferol 3-O-rutinoside, isorhamnetin 3-O-glucoside, and morin as the major flavonoids in all extracts.
Article
Limited information is available concerning the qualitative and quantitative composition of polyphenolic compounds, especially flavonoids, in almonds. We determined total phenols, flavonoids, and phenolic acids in California almond (Prunus dulcis) skins and kernels among the principal almond varieties (Butte, Carmel, Fritz, Mission, Monterey, Nonpareil, Padre, and Price) with high-performance liquid chromatography (HPLC)/electrochemical detection and UV detection. Liquid chromatography/tandem mass spectrometry under identical HPLC conditions was utilized to verify identities of the predominant flavonoids and phenolic acids. Total phenols ranged from 127 (Fritz) to 241 (Padre) mg gallic acid equivalents/100 g of fresh weight. The analyses were compiled to produce a data set of 18 flavonoids and three phenolic acids. The predominant flavonoids were isorhamnetin-3-O-rutinoside and isorhamnetin-3-O-glucoside (in combination), catechin, kaempferol-3-O-rutinoside, epicatechin, quercetin-3-O-galactoside, and isorhamnetin-3-O-galactoside at 16.81, 1.93, 1.17, 0.85, 0.83, and 0.50 mg/100 g of fresh weight almonds, respectively. Using the existing approach of calculating only the aglycone form of flavonoids for use in the U.S. Department of Agriculture nutrient database, whole almonds would provide the most prevalent aglycones of isorhamnetin at 11.70 (3.32), kaempferol at 0.60 (0.17), catechin at 1.93 (0.55), quercetin at 0.72 (0.20), and epicatechin at 0.85 (0.24) mg/100 g of fresh weight (mg/oz serving), respectively. These data can lead to a better understanding of the mechanisms of action underlying the relationship between almond consumption and health-related outcomes and provide values for whole and blanched almonds suitable for inclusion in nutrient databases.
Article
The current research involves the study of the thermal treatment of quercetin and rutin in an aqueous model system (cooking). These substances were heated and their degradation was followed by high-performance liquid chromatography/diode-array detection (HPLC/DAD). The influence of pH and the involvement of oxygen in the degradation were studied. HPLC/electrospray ionization multi-stage mass spectrometry (ESI-MS(n)) was used for the structural characterization of the compounds produced. The influence of the degradation of the phenolic compounds on their antioxidant properties was elucidated by a electron spin resonance (ESR) spectrometry study of the reaction samples mixed with the stabilized radical, Fremy's salt. Strong degradation of the model substances took place under weak basic and oxidative conditions. Quercetin showed the most intense degradation. Protocatechuic acid could be identified as a cleavage reaction product by analyzing its retention time and molar mass during the degradation of quercetin. The structure of a second cleavage product could be identified on the basis of ESI-MS(n) fragmentation data. Also, several structures for reaction products of oxidized quercetin are suggested. The ESR analysis showed a decrease in the antioxidant activity of the reaction samples after heat treatment in aqueous solution.
Article
This paper reports the effects of heat treatment on huyou (Citrus paradisi Changshanhuyou) peel in terms of phenolic compounds and antioxidant capacity. High-performance liquid chromatography (HPLC) coupled with a photodiode array (PDA) detector was used in this study for the analysis of phenolic acids (divided into four fractions: free, ester, glycoside, and ester-bound) and flavanone glycosides (FGs) in huyou peel (HP) before and after heat treatment. The results showed that after heat treatment, the free fraction of phenolic acids increased, whereas ester, glycoside, and ester-bound fractions decreased and the content of total FGs declined (P < 0.05). Furthermore, the antioxidant activity of methanol extract of HP increased (P < 0.05), which was evaluated by total phenolics contents (TPC) assay, 2,2'-azinobis(3-ethylbenzothiazoline-6-sulfonate) (ABTS*+) method, and ferric reducing antioxidant power (FRAP) assay. The correlation coefficients among TPC, ABTS, FRAP assay, and total cinnamics and benzoics (TCB) in the free fraction were significantly high (P < 0.05), which meant that the increase of total antioxidant capacity (TAC) of HP extract was due at least in part to the increase of TCB in free fraction. In addition, FGs may be destroyed when heated at higher temperature for a long time (for example, 120 degrees C for 90 min or 150 degrees C for 30 min). Therefore, it is suggested that a proper and reasonable heat treatment could be used to enhance the antioxidant capacity of citrus peel.
Article
Flavonoids are an important constituent of the human diet. In recent years, they have gained much attention due to their physiological properties, leading to an enormous increase in research on cancer prevention and reduction of cardiovascular diseases. Unfortunately, there is limited information about the fate of flavonoid glycosides during thermal treatment such as cooking, frying, roasting, etc. Such processing techniques may have an impact on the flavonoid structure, resulting in changes of the bioavailability and activity of the flavonoids. In this study, the stability of selected model and onion quercetin glycosides under roasting conditions (180 degrees C) was determined. The influence of the kind and position of the sugar moiety was investigated. As onions contain large amounts of quercetin glycosides and are often subject to thermal processes in food production, their major glycosides were isolated using counter current chromatography and roaste