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Oxidative stability of virgin olive oil

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Abstract

Virgin olive oil has a high resistance to oxidative deterioration due to both a triacylglycerol composition low in polyunsaturated fatty acids and a group of phenolic antioxidants composed mainly of polyphenols and tocopherols. Polyphenols are of greater importance to virgin olive oil stability as compared with other refined oils which are eliminated or drastically reduced during the refining process.This paper covers the main aspects related to the oxidative stability of virgin olive oil during storage as well as at the high temperatures of the main processes of food preparation, i.e., frying and baking. Differences between oxidation pathways at low and high temperature are explained and the general methods for the measurement of stability are commented on. The compounds contributing to the oxidative stability of virgin olive oils are defined with special emphasis on the antioxidative activity of phenolic compounds. Finally, the variables and parameters influencing the composition of virgin olive oils before, during and after extraction are discussed.

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... Lipid oxidation depends on availability of substrates (oxygen and oxidable compounds, such as polyunsaturated fatty acids (PUFA)) and on the balance between antioxidants (such as tocopherols (T), among others) and pro-oxidants (such as certain mineral elements). Thus, the oxidation process is influenced by factors inherent to fats and oils (e.g., FA profile, free fatty acid (FFA) content, antioxidants, and pro-oxidants), and by external factors, such as processing and storage conditions (light exposure, temperature, and oxygen availability) [2,3]. ...
... p ≤ 0.05 was considered significant. 2 Table shows the sums of fatty acids, including all the identified and quantified FA, expressed as internal area normalization in %. SFA includes: C6:0, C8:0, C10:0, C11:0, C12:0, C13:0, C14:0, C15:0, C16:0, C17:0, C18:0, C20:0, C21:0, C22:0, C23:0, and C24:0; cis-MUFA includes C16:1 n-9, C16:1 n-7, C18:1 n-9, C18:1 n-7, and C20:1 n-9; n-6 PUFA includes C18:2 n-6 and C20:2 n-6; n-3 PUFA includes C18:3 n-3; trans-C18:1 includes a sum of positional isomers. ...
... The higher POL content in AO compared to FAD was also reflected when the two OFAD samples were compared with the O samples. POL mainly consist of triacylglycerol polymers created by the reaction of triacylglycerol radicals and accumulated in the advanced stages of oxidation [2]. In general, the formation of POL is higher in oils with higher PUFA contents, because they are more prone to form radicals [47]. ...
Article
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Acid oils (AO) and fatty acid distillates (FAD) are byproducts from chemical and physical refining of edible oils and fats, respectively. Their high energy value makes their upcycling interesting as alternatives to conventional fats in animal feeding. The objective of this study is to characterize their oxidative quality and to provide recommendations about their evaluation for animal feeding purposes. The oxidation status (peroxide value (PV), p-Anisidine value (p-AnV), % polymeric compounds (POL)), the oxidative stability (induction time by the Rancimat at 120 °C (IT)), the fatty acid composition (FA), and tocopherol and tocotrienol content of 92 AO and FAD samples from the Spanish market were analyzed. Both AO and FAD showed low PV (0.8 and 1 meq O2/kg); however, p-AnV was higher in FAD (36.4 vs. 16.4 in AO) and POL was higher in AO (2.5% vs. not detected in FAD) as a consequence of the type of refining process. The botanical origin of AO and FAD influenced FA and tocol composition, and they influenced IT. A high variability was observed for most analyzed parameters, reinforcing the need for standardizing AO and FAD to obtain reliable feed ingredients and to include primary and secondary oxidative parameters within their quality control.
... Furthermore, oil quality and stability are also affected by variations in fatty acid compositions and antioxidant contents [6,7]. Despite their nutritional benefits, LA and ALA are more prone to oxidative deterioration during storage and high heat application [8]. ...
... Factors such as percentage of free fatty acids (FFA), peroxide value (PV), amounts of β-carotene, type of fatty acids, and specific extinction coefficient are widely used. Others are changes in the number of phenols, tocopherols, and oxidative stability [7]. In most cases, these parameters are determined simultaneously to enable precision in the evaluation of oil stability. ...
... Fatty Acid (FFA) Contents. Due to high temperature, enzymatic activities, or high moisture contents in oil, hydrolysis of triglycerides occurs due to the detachment of fatty acid tails from glycerol molecules resulting in the formation of FFAs [7]. FFAs are highly susceptible to oxidation; hence, they indicate deterioration in oils [6]. ...
Article
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The selection of healthy fats for consumption is important. Linoleic acid (LA) (omega-6) and alpha-linolenic acid (ALA) (omega-3) are essential polyunsaturated fatty acids required for the maintenance of good health; however, LA derivatives such as arachidonic acid (AA) are associated with the onset of inflammatory diseases, and both are prone to oxidation and deterioration. This study compared the fatty acid contents, peroxide value (PV), p-anisidine value (p-AV), and free fatty acids (FFA) of the oyster nut oil with refined sunflower, nonrefined sunflower, and flaxseed oil stored at 27°C for 40 days. Flaxseed oil had significantly high ALA content (59.8%) compared to 0.1-0.5% for oyster nut and sunflower oil brands. The LA content was high in sunflower brands (50.3-52.8%) compared to the oyster nut (48%) and flaxseed oil 14.7%. Oleic acid was lower in oyster nut oil (8.6%) and flaxseed oil 15.8% compared to sunflower brands (35.7-38.2%). As a consequence, oyster nut and flaxseed recorded higher PV of 4.35-2.88 mEq O2/kg and FFA 0.26-0.47% compared to sunflower brands. The p-AV recorded small values which were not significantly different in all samples. Although oyster nut is widely consumed by pregnant and lactating women across Africa, its keeping quality in nonrefined form is low compared to flaxseed and sunflower oil as shown in this study. Hence, the fatty acid contents in oyster nuts should be consumed in other alternative forms such as flour and roasted kernels rather than its oil when in nonrefined form. This study will enable the consumption balance of omega-6/omega-3 fatty acids and the keeping quality of oils which is key to health.
... This research group, in a previous paper [18], described an ASLT carried out in the dark at mild temperatures (40,50, and 60 • C), where the autoxidation kinetic behaviour of the main oxidation indices (PV, K232, and K270) and the oxidising substrate (unsaturated fatty acids (UFA)) were reported for the first time. K232 showed high linearity in the early stages of oxidation and presented an excellent correlation with the loss of UFA. ...
... From the study of oxidation parameters and fatty acids degradation rates between 25 and 60 • C, this research group proposed the TRUL (Time to Reach the Upper legal Limit) parameter, related to K232, as a value for predicting oxidative stability at 25 • C, from ASLT at a temperature lower than 60 • C [18]. As a result, the predicted TRUL at 25 • C when applying the proposed model to accelerated storage temperatures (40,50 and 60 • C) was very close to the experimental TRUL at the same temperature. ...
... The high MUFAs/PUFAs ratio, which is typical of olive oil, is one of the main reasons for the higher stability of olive oil with respect to other edible oils [50,51]. In the studied samples, this ratio ranged from 13.5 to 19.4. ...
Article
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The development of effective shelf-life prediction models is extremely important for the olive oil industry. This research is the continuation of a previous accelerated shelf-life test at mild temperature (40–60 °C), applied in this case to evaluate the oxidation effect of temperature on minor components (phenols, tocopherol, pigments) to properly complete a shelf-life predictive model. The kinetic behaviour of phenolic compounds, α-tocopherol and pigments during storage of different virgin olive oil samples at different temperatures (25–60 °C) is reported. Hydroxytyrosol, tyrosol and α-tocopherol fitted to pseudo-zero-order kinetics, whereas secoiridoid derivatives of hydroxytyrosol and tyrosol, o-diphenols and total phenols apparently followed pseudo-first-order kinetics. The temperature-dependent kinetic of phenolic compounds and α-tocopherol were well described by the linear Arrhenius model. The apparent activation energy was calculated. Principal component analysis was used to transform the considered compositional and degradation variables into fewer uncorrelated principal components resulting in 4: “no oxidizable substrate”, “initial oxidation state and conditions”, “free simple phenols”, and “degradation rates”. In addition, multivariate linear regression was used to yield several modelling equations for shelf-life prediction, considering initial composition and experimental variables easily determined in accelerated storage.
... Oil production is a seasonal output that lasts only a few months (two or three), whereas oil sales can take up to two years. Oxidative stability represents the shelf life of an oil (Velasco, 2002). Therefore, identifying varieties with higher oxidative stability allows a longer time for storage and sale. ...
... The total phenolic content was not correlated with oxidative stability (r = 0.12) (data not shown). Unlike what was observed by Aparicio et al. (1999) and Velasco (2002), most of the assays have been done over a small number of varieties, while in this work, 18 varieties were used. Probably, the high genetic variability and the narrow range observed among total phenolic compounds can explain the lack of correlation. ...
Article
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There are more than 2000 varieties of olives grown worldwide, of which only a few (2 %) are cultivated in Argentina. Mendoza is one of the main oil-producing provinces in the country due to its adequate agroecological conditions. In addition, Mendoza has an olive germplasm collection with over 70 accessions. This work aimed to characterize olive oil from 18 preselected varieties in the collection for qualitative characteristics that are important to the olive industry (i.e., industrial yield, acidity, oxidative stability, total phenolic compounds and phenolic profile). As a result, all evaluated characteristics were significantly different among varieties (p < 0.001) and allowed identifying excellent qualities in varieties not currently cultivated. Five scarcely cultivated varieties (‘Villalonga’, ‘Nebbio’, ‘Nevadillo Blanco’, ‘Canino’, and ‘Piangente’) were highlighted above the most widespread cultivars in Mendoza, Argentina. Featuring on average of 14 % of industrial yield, 15 h of oxidative stability and 373 mg kg⁻¹ of total phenolic compounds.
... Recent investigations have underlined the importance of storage conditions (e.g., light, temperature, and oxygen) (Iqdiam et al., 2020;Caipo et al., 2021) and packaging material (Pristouri et al., 2010;Dabbou et al., 2011) in the preservation of EVOO quality during storage. It is well established that under storage in the dark and at room temperature the degradation of EVOOs is mainly related to the autoxidation processes (Velasco and Dobarganes, 2002;Esposto et al., 2020). The rate of EVOO deterioration during storage, among other parameters, is dependent on the initial content of phenolic compounds (Gómez-Alonso et al., 2007;Esposto et al., 2020;Castillo-Luna et al., 2021) but also on the specific overall chemical profile deriving from a particular olive cultivar (Brkić Bubola et al., 2014;Kotsiou and Tasioula-Margari, 2016). ...
... Regarding the individual phenolic compounds, the dynamic of their degradation can be considered specific for each compound and related to each cultivar of EVOO (Table 2). Secoiridoids, as the most abundant group of phenolic compounds, degraded at the highest rate due to hydrolysis and autoxidation processes known to occur during storage (Velasco and Dobarganes, 2002;Esposto et al., 2020). Specifically, oleuropein and ligstroside aglycones have probably undergone hydrolysis reactions and decreased at a small rate after 7 and 14 days of storage for IB and B oils, respectively (Table 2). ...
Article
The present study investigated the changes in extra virgin olive oil (EVOO) quality, health, and flavour properties during simulated domestic consumption conditions in which the EVOO bottles were reopened daily, thereby gradually increasing the headspace. Quality parameters, phenolic and volatile compounds, and sensory attributes of two monovarietal EVOOs, Istarska bjelica (IB) and Buža (B), have been evaluated every seven days for one month. After storage, the total phenolic content decreased by 12.3 and 17.6% in IB and B EVOOs, respectively, while the total concentration of volatile compounds decreased by approximately 19%. However, the results have shown that no enhanced degradation of phenolic and volatile compounds has been noted in EVOOs stored under consumption conditions compared to the ones stored unopened during the same period, implying that the degradation degree was predominantly attributed to oil aging. The principal component analysis emphasized peroxide value and sensory attributes as parameters that segregated EVOOs under consumption conditions from the fresh and unopened ones. Furthermore, the conditions in which EVOO was consumed in a recommended daily dosage (20 g) during one-month storage did not reduce its phenolic content under the levels required for the EFSA health claim application.
... 5 Numerous studies have been conducted on the effects of storage temperature on the quality of olive oil. Some authors have studied the shelf life of olive oil stored at high temperatures, and have highlighted a sharp decline in olive oil quality indicators (peroxide value, free acid value and total phenols content) [28][29][30][31][32][33] . ...
Chapter
The high oxidative stability of virgin olive oil with respect to other vegetable oils is mainly due to its fatty acid composition, in particular, to the high monounsaturated-to-polyunsaturated ratio, and to the presence of minor compounds that play a major role in preventing oxidation. In spite of its high stability, virgin olive oil is susceptible to oxidative processes, such as enzymatic oxidation, photooxidation, and autoxidation, which mainly occur during processing and storage. Generally, extra-virgin olive oil has a relatively long shelf life of 16–18 months of storage at room temperature. The study of shelf life is generally based on determining of quality parameters (acidity, peroxide index, and ultraviolet absorption). These parameters, which indicate primary oxidation states, can be associated with determination of minor constituents such as secoiridoid derivatives and their degradation products.
... Olive (Olea europaea L.) oil is a significant part of the Mediterranean diet (Dag et al., 2011). Virgin olive oil draws the attention because of its fatty acid composition characterized by the high amount of monounsaturated fatty acids, and its phenolic compounds that exhibit great antioxidant activity (Velasco and Dobarganes, 2002). The physical processes, such as crushing, malaxation and separation in comparison to chemical techniques provide the better nutritional value and organoleptic properties to virgin olive oil (Boselli et al., 2009;Taticchi et al., 2013). ...
... It was also noted that shorter heat treatment duration to the detached palm fruits likely reduced the oxidative stability of oil produced. Studies showed that oil processing with prolonged heat treatment at high temperature caused oil oxidation (Khor et al., 2019;Oboh et al., 2014;Velasco & Dobarganes, 2002). This finding is strengthened by the increase of DOBI in E-CPO, which means oil deterioration due to oxidation was slowed down with low FFA and contaminants level. ...
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Quality and food safety are of paramount importance to the palm oil industry. In this work, we investigated the practicability of ethylene gas exogenous application on post‐harvested oil palm fruit bunches to improve the crude palm oil (CPO) quality. The bunches were first exposed to ethylene gas for 24 hr to induce abscission of palm fruits from bunches. The detached fruits were then subjected to heat treatment, mechanical extraction, clarification and drying to produce CPO. Critical quality parameters of CPO produced, that is free fatty acid, deterioration of the bleachability index and triacylglycerol showed improvement with ethylene gas treatment. Contaminant content that is phosphorus, chloride, iron, and copper also showed a reduction in the CPO derived from ethylene‐treated bunches. These findings corresponded with low levels of contaminants such as 3‐monochloro‐1, 2‐propanediol esters and glycidyl esters in refined oil. The implementation strategy and practicability of this method is herein proposed and discussed. Ethylene application not only improves the CPO quality, but could potentially enhance the process sustainability of palm oil mills. Ethylene (C2H4) gas application on oil palm fruit bunches improves crude palm oil quality. C2H4 gas application on palm fruit bunches reduces contaminants in crude palm oil which promote the formation of carcinogenic compounds (3‐chloropropan‐1,2‐diol esters and glycidyl esters) during the refining process. Industrial practicability and implementation strategy are discussed.
... They were assayed as primary antioxidants of olive oils by many researchers (e.g. Gutiérrez, Arnaud, & Garrido, 2001;Lanza & Ninfali, 2020;Velasco & Dobarganes, 2002). Various authors have demonstrated a positive linear relationship between olive oil stability and both the total content of phenolic compounds (Blekas, Vassilakis, Harizanis, Tsimidou, & Boskou, 2002;Mansouri et al., 2016;Nieves Franco et al., 2014) and the contents of individual groups, such as phenolic alcohol derivatives (Cerretani, Bendini, Rotondi, Lercker, & Toschi, 2005), secoiridoids (Baccouri et al., 2008), and aglyconic derivatives (Bendini, Cerretani, Vecchi, Carrasco-Pancorbo, & Lercker, 2006;Mansouri et al., 2016). ...
Article
Background Phenolic compounds from different plant sources, like fruits, vegetables, cereals, and herbs, have been excessively studied and widely used in different industrial areas, including food, medicine, and pharmaceuticals. Recently, special attention has been paid to the phenolic compounds of plant oils that have recently been found to vastly affect the oxidative stability of these products. Scope and approach This paper reviews the contents and types of phenolic compounds in their initial forms in plant oils and methods of their determination. Also, their impact on the oxidative stability of oils is discussed. Key findings and conclusions The total free content of phenolic compounds and the phenol profile in plant oils are very diverse and depend on the oil source and production method. Generally, the main oily source of these compounds is rice brans and olive fruits. Their high amounts can also be found in rapeseed, flaxseed, grapeseed, and pumpkin oils. The main groups of phenolic compounds in oils are phenolic acids and flavonoids. Additionally, lignans, secoiridoids, and phenolic derivatives are identified in some oils. The two main methods for the determination of phenolic compounds in oils include the spectrophotometric and chromatographic ones. The general principles of these assays are often modified by various authors to adapt them to research conditions. Available literature data confirmed the strong antioxidative activity of some phenolic compounds found in oils. However, further studies are needed to better understand the mechanism of their protective action on oils, especially under natural storage.
... Despite the degradation mechanism, temperature and oxygen concentration are the main external variables that determine the rates of formation of lipid peroxy radicals and hydroperoxides. According to a previous work [44], under normal degradation treatment with moderate temperature, such as room temperature, the solubilization of oxygen is high. As a result, the oxidation process is initiated, and lipid alkyl radicals are the most common species present and hydroperoxides are the major products formed. ...
Article
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The effect of different cooking processes such as frying and roasting on the oxidative stability of sunflower seeds was evaluated under accelerated oxidation and normal storage conditions. The fatty acid composition by GC-MS showed a higher amount of linoleic acid in fried samples due to the replacement of the seed moisture by the frying oil. On the other hand, roasted samples presented a higher oleic acid content. DSC and TGA results showed some decrease in the thermal stability of sunflower seed samples, whereas PV and AV showed the formation of primary and secondary products, with increasing oxidation time. Roasted sunflower seeds showed seven main volatile compounds characteristic of the roasting process by HS-SPME-GC-MS: 2-pentylfuran, 2,3-dimethyl-pyrazine, methyl-pyrazine, 2-octanone, 2-ethyl-6-methylpyrazine, trimethyl-pyrazine, and trans,cis-2,4-decadienal, whereas fried samples showed six volatile characteristic compounds of the frying process: butanal, 2-methyl-butanal, 3-methyl-butanal, heptanal, 1-hexanol, and trans,trans-2,4-decadienal. The generation of hydroperoxides, their degradation, and the formation of secondary oxidation products were also investigated by ATR-FTIR analysis. The proposed methodologies in this work could be suitable for monitoring the quality and shelf-life of commercial processed sunflower seeds with storage time.
... The different basal levels of PV and AnV between examined VCO and VOO could be contributed by many factors, including the natural lipid oxidation in seeds, manufacturing, and storage conditions (Velasco & Dobarganes, 2002;Zhu et al., 2020). Overall, AnV serves as a better indicator than PV and TBARS to reflect the oxidative status of camellia and olive oils under thermal stress. ...
Article
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Camellia oil is widely recognized as a high‐quality culinary oil in East Asia for its organoleptic and health‐promoting properties, but its chemical composition and thermal stability have not been comprehensively defined by comparisons with other oils. In this study, the triacylglycerols (TAGs) in camellia, olive, and six other edible oils were profiled by the liquid chromatography‐mass spectrometry (LC‐MS)‐based chemometric analysis. Besides observing the similarity between camellia oil and olive oil, TAG profiling showed that OOO, POO, and OOG (O: oleic acid, P: palmitic acid, and G: gadoleic acid) can jointly serve as the identity markers of camellia oil. Thermal stability of virgin camellia oil (VCO) was further evaluated by extensive comparisons with virgin olive oil (VOO) in common lipid oxidation indicators, aldehyde production, and antioxidant and pro‐oxidant contents. The results showed that p‐anisidine value (AnV) was the sensitive lipid oxidation indicator, and C9‐C11 aldehydes, including nonanal, 2‐decenal, 2,4‐decadienal, and 2‐undecenal, were the most abundant aldehydes in heated VCO and VOO. Under the frying temperature, heated VCO had lower AnV and less aldehydes than heated VOO. Interestedly, the VCO had lower levels of pro‐oxidant components, including α‐linolenic acid, free fatty acids, and transition metals, as well as lower levels of antioxidants, including α‐tocopherol and phenolics, than the VOO. Overall, great similarities and subtle differences in TAG and aldehyde profiles were observed between camellia and olive oils, and the thermal stability of camellia oil might be more dependent on the balance among its unsaturation level, pro‐oxidant, and antioxidant components than a single factor.
... The use of a panel of experts for the sensory analysis is expensive, time-consuming, and unable to perform quantitative determinations, thus being unfeasible for routine inspections. In this scenario, the identification and/or determination of the volatile compounds by instrumental techniques or chemical sensors are an excellent alternative that can be tailored to evaluate the quality of oil samples so as to discriminate olive oils from adulterated oils (Escuderos et al., 2013) and detect rancid defects (Aparicio, Rocha, Delgadillo, & Morales, 2000), the oxidation status (Velasco & Dobarganes, 2002), or the deterioration caused by external factors. ...
Article
Olive oil is an appreciated food product with high nutritional value, besides being an essential component in many culture diets. In this study, we present for the first time the application of a simple and non-invasive paper-based optoelectronic nose designed in a QR code configuration to evaluate the odor of olive oils. The chemical QR code was fabricated by the addition of 12 dyes, which provided high dimensional data resulting from the interaction between the volatile compounds and the colorimetric array. The color changes were employed to build differential maps with a unique fingerprint (i) to discriminate between olive oil and other edible oil samples; (ii) to quantify nonanaldehyde as an oxidation marker; and (iii) to identify oxidized oils through principal component analysis (PCA) and hierarchical component analysis (HCA). By developing suitable mobile apps, we anticipate the employment of the chemical QR code for portable, low-cost, and in-situ evaluation of food product quality.
... These tendencies are consistent with the findings of Rotich et al. (2020) and Gutiérrez and Fernández (2002) when assessing the effects of temperature and storage time on EVOO. Velasco and Dobarganes (2002) reported that adding adulterants to olive oil increases oxidant concentrations, and this results in the breakdown of hydroperoxide substances, thereby accumulating carboxylic acids, which later increase acidity. Acidity increase during adulteration leads to hydro-peroxide accumulation which is dominant in lower-grade oils, and this excites the triplet oxygen from ground energy state to singlet state, triggering the reaction to produce free fatty acids in excess (Hamilton et al., 1997), hence generating more acids. ...
Article
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Adulterating extra-virgin olive oils (EVOO) with lower grade olive oils, like virgin olive oil (VOO), and selling it as EVOO to unsuspecting consumers has sparked concern in the recent years. Developing inexpensive and quick adulteration detection methods to unravel such acts will promote trust in the industry. This study focused on the quality degradation of EVOO when adulterated by different proportions of VOO. Excitation Emission Matrices (EEMs) and fluorescence images were taken for analysis. Partial least square regression (PLSR), support vector machine (SVM), decision tree and convolutional neural network (CNN) models were used to explore both the EEMs and fluorescence images of adulterated oils, which indicate the extent of adulteration of extra virgin olive oils can be detected.
... The tendency of these results agrees with those reported by Gutiérrez and Fernández (2002) and Rotich et al. (2020) when evaluating temperature and storage time for EVOO. By adding more adulterants (VOO), the concentration of oxidants increases, resulting in the formation and decomposition of hydroperoxide thereby forming carboxylic acids which, in return, increases the acidity (Velasco & Dobarganes, 2002). Increasing acidity values during adulteration process is facilitated by the accumulation of oxygen and hydro-peroxide compounds from the lower grade oil and those formed from EVOO during degradation transforming the excess energy ground state triplet oxygen to the excited singlet state, hence reacting to produce more free fatty acids (Hamilton, Kalu, Prisk, Padley, & Pierce, 1997) thereby producing more acids. ...
Article
Due to the health benefits of extra virgin olive oil (EVOO) and its increasing consumption patterns, adulteration of these oils using lower grade olive oils like virgin olive oil (VOO) and then later sold as EVOO to unsuspecting consumers has become a concern in the industry. There is a need for quick, reliable and inexpensive detection techniques to unmask such vice in order to realize its benefits. In this study, adulteration of EVOO is made using VOO at different proportions; their Excitation Emission Matrices (EEM) were examined using Front-face fluorescence spectroscopy and their corresponding fluorescence images captured using 365 nm ultra-violet (UV) LED for analysis. Specific regions for both the EEM and imaging were explored using Support Vector Machine (SVM) classification analysis and their sensitivities evaluated using Partial Least Squares Regression (PLSR) analysis. It was found that EEM excitation 230-500 and emission 260-620 nm could easily discriminate between different samples as EVOO mixed (at different ratios) and VOO. The significant fluorescence peaks for the discrimination forms a combination of Tocopherols, Tocotrienols, Phenolic compounds, Oxidation products and Vitamin E. The results show that Front-face fluorescence spectroscopy and UV-induced fluorescence imaging can potentially discriminate between pure EVOO and adulterated olive oils.
... In this investigation, external factors, such as light and high temperature, known to accelerate the oxidative degradation of EVOOs [37], were reduced to a minimum by using low temperature and dark conditions to single out the influence of the cheese presence on the EVOO oxidative degradation. It is well known that in such storage conditions, the degradation of EVOO is mainly related to the autooxidation processes [38]. ...
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The influence of semi-hard (C1), hard (C2), and soft whey cheese (C3) immersed in extra virgin olive oil (EVOO) on its oxidative and hydrolytic parameters, fatty acids, and phenolic composition during two months of simultaneous storage was investigated. Accelerated hydrolytic and oxidative degradation was noted in EVOO stored with the immersed cheese compared to control oil. Oxidation indicator (K232), myristic (C 14:0), and trans-oleic fatty acid (C18:1t) exceeded the prescribed limit for the EVOO category in oils stored with immersed C1 and C2, which indicated that standard analytical parameters are ineffective as tools to examine the declared quality and authenticity of such topping oils. The noted changes in fatty acid profile were primarily prescribed to the migration of fats. C1 and C2 influenced a comparable reduction in EVOO total identified phenolic content (−92.1% and −93.5%, respectively), despite having a different content of total proteins and moisture, whereas C3 influenced a slightly lower reduction (−85.0%). Besides the protein profile, other cheese compounds (e.g., moisture, carbohydrates) have been shown to have a considerable role in the development of the EVOO phenolic profile. Finally, compositional changes in EVOO used as a medium for cheese preservation are under significant influence of the cheese’s chemical composition.
... The bioactive components of extra virgin olive oil are result of a number of variables acting before extraction (such as olive variety, environmental, climatic, soil and cultivation condition, olive ripeness, and olive healthy ) and during extra virgin olive oil extraction and storage (Velasco & Dobarganes, 2002). As shown in Table (3), the phenolic contents, orthdiphenols and bitter index of extra virgin olive oil were affected by olive varity and de-stoning. ...
... [1][2][3][4][5][6] This enhancement has been attributed to the fatty acid composition of oils, which are characterized by high ratios of mono-unsaturated fatty acid content to poly-unsaturated fatty acid content and the presence of minor compounds with powerful antioxidant activity, especially polyphenols. 7,8) In addition, based on the recommendations of the World Health Organization (WHO), any oil can be characterized based on three parameters: proportions of its saturated, and mono-and poly-unsaturated fatty acid contents, proportions of essential fatty acids, and presence of antioxidants. The WHO recommends dietary ratios of 1:1.5:1 for saturated: mono-unsaturated: poly-unsaturated fatty acid contents and 5-10:1 for linoleic acid: alpha linoleic acid. ...
Article
We prepared blended oil using soybean oil (SR10) and rapeseed oil (SR01), and evaluated the quality of deteriorated pure and blended oils (with weight/volume ratio of soybean oil to rapeseed oil of 2:1, 1:1, and 1:2) by heat treatment and aeration. The ratio of the acid value following deterioration (AV) to its initial value (AV0) i.e., the value of AV/AV0 was in the order SR10 (3.29) << SR01 (7.50). On the other hand, the ratio of the carbonyl value after deterioration (CV) to its initial value (CV0) i.e., the value of CV/CV0 decreased with increase in the proportion of rapeseed oil in the blended oil (SR01 (3.12) << SR10 (4.15)). We thus establish that the fatty acid component of the blended oil is a very important factor in the deterioration of edible oil by heat treatment and aeration. Next, we evaluated the improvement in the quality of deteriorated oil by calcium silicate adsorbent (Ca:Si = 1:3, CAS30) treatment i.e., adsorption. It is established that CAS30 exhibited the ability to remove AV and CV from deteriorated oil (treatment temperature: 80 °C < 100 °C). Moreover, we investigated the removal mechanism of AV and CV, and determined good positively or negatively linear relationship between AV or CV removal by CAS30 and the proportion of unsaturated fatty acid in deteriorated pure and blended oils. In summary, the results obtained from treatment with CAS30 provided useful information on improvement in the quality of deteriorated blended oil.
... In order to prevent the oxidation of VOCs by oxygen, inert gases such as argon might be employed in the storage of essential oils. With regards to temperature-dependent degradation, alkyl or hydroxy radicals within plant VOCs are responsible for oxidation at high temperatures due to the limited amount of oxygen [100]. ...
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Plant volatile organic compounds (volatiles) are secondary plant metabolites that play crucial roles in the reproduction, defence, and interactions with other vegetation. They have been shown to exhibit a broad range of biological properties and have been investigated for antimicrobial and anticancer activities. In addition, they are thought be more environmentally friendly than many other synthetic chemicals 1. Despite these facts, their applications in the medical, food, and agricultural fields are considerably restricted due to their volatilities, instabilities, and aqueous insolubilities. Nanoparticle encapsulation of plant volatile organic compounds is regarded as one of the best strategies that could lead to the enhancement of the bioavailability and biological activity of the volatile compounds by overcoming their physical limitations and promoting their controlled release and cellular absorption. In this review, we will discuss the biosynthesis and analysis of plant volatile organic compounds, their biological activities, and limitations. Furthermore, different types of nanoparticle platforms used to encapsulate the volatiles and the biological efficacies of nanoencapsulated volatile organic compounds will be covered.
... The chlorophyll/carotenoid ratio is low. In the presence of light, chlorophylls and their derivatives are the most active promoters of photosensitized oxidation in virgin olive oil contributing greatly to a high susceptibility to oxidation [65]. Carotenoids possess conjugated hydrocarbons which are potent protectors against photosensitized oxidation, acting as singlet oxygen quencher [66]. ...
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Food diversity, and in particular genetic diversity, is being lost at an alarming rate. Protection of natural areas is crucial to safeguard the world’s threatened species. The Medes Islands (MI), located in the northwest Mediterranean Sea, are a protected natural reserve. Wild olive trees also known as oleasters make up part of the vegetation of the Meda Gran island. Among them, in 2012, a wild albino ivory-white olive tree with fruit was identified. Fruits were collected from this tree and their seeds were first sown in a greenhouse and then planted in an orchard for purposes of ex situ preservation. Seven out of the 78 seedling trees obtained (12%) produced ivory-white fruits. In autumn 2018, fruits from these trees were sampled. Although the fruits had low oil content, virgin olive oil with unique sensory, physicochemical, and stability characteristics was produced. With respect to the polyphenols content, oleacein was the main compound identified (373.29 ± 72.02 mg/kg) and the oleocanthal was the second most abundant phenolic compound (204.84 ± 52.58 mg/kg). Regarding pigments, samples were characterized by an intense yellow color, with 12.5 ± 4.6 mg/kg of chlorophyll and 9.2 ± 3.3 mg/kg of carotenoids. Finally, oleic acid was the main fatty acid identified. This study explored the resources of the natural habitat of the MI as a means of enrichment of olive oil diversity and authenticity of this traditional Mediterranean food
... Available online at preprints.aijr.org production of oxylipins was also observed [169]. These studies indicate the anti-platelet aggregation and protective mechanisms of olive oil phenols. ...
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can affect replication or protease activity of coronavirus. The clinical testing and regulatory approvals for these drugs will take time. However, currently there is an urgent requirement of treatment strategies which are safe, effective and can be implemented through readily available products in market. Many plant derived products rich in secondary metabolites having potential health benefits and antimicrobial properties. The olive plant leaf extracts and olive oil are rich sources of secondary metabolites such as phenols (oleuropein and hydroxytyrosol) and terpenoids (oleanolic, maslinic and ursolic acid). These compounds have been used as an effective antiviral agents in the past. The phenolics affect the virus attachment and replication. Whereas, the terpenoids mainly affects the membrane fluidity of the virus. In the recent molecular docking studies, it was found that, these compounds effectively bound to Mpro and 3CL pro protease sites of SARS-CoV-2 and were predicted to affect the replication of the SARS-CoV-2. Apart from antiviral properties, these bioactive compounds possess various other pharmacological properties such as anti-inflammatory, anti-modulatory, anti-thrombotic and anti-oxidative. The olive oil is consumed as a source of dietary fat and is the secret behind the good health in Mediterranean people. The consumption of olive oil is safe and is believed to increase the immunity against various infectious microbes. Hence olive products can be explored in management of COVID-19. In this review the various properties of phenolic and terpenoid compounds found in olives were discussed in the context of COVID-19.
... EVOO is a source of phenolic compounds with antioxidant activity that may help to prevent degradation of C 60 -OO. EVOO was selected as a carrier because the cold-press extraction method used in EVOO production generates fewer oxidation products than heat-extracted OO under normal storage conditions [29,30]. We exactly replicated the dosing and the administration strategy proposed in the original study of C60 in rats using separate randomized groups of adult and old C57BL/6 J mice in C 60 -EVOO or EVOO alone groups [14]. ...
Article
C60 is a potent antioxidant that has been reported to substantially extend the lifespan of rodents when formulated in olive oil (C60-OO) or extra virgin olive oil (C60-EVOO). Despite there being no regulated form of C60-OO, people have begun obtaining it from online sources and dosing it to themselves or their pets, presumably with the assumption of safety and efficacy. In this study, we obtain C60-OO from a sample of online vendors, and find marked discrepancies in appearance, impurity profile, concentration, and activity relative to pristine C60-OO formulated in-house. We additionally find that pristine C60-OO causes no acute toxicity in a rodent model but does form toxic species that can cause significant morbidity and mortality in mice in under 2 weeks when exposed to light levels consistent with ambient light. Intraperitoneal injections of C60-OO did not affect the lifespan of CB6F1 female mice. Finally, we conduct a lifespan and health span study in males and females C57BL/6 J mice comparing oral treatment with pristine C60-EVOO and EVOO alone versus untreated controls. We failed to observe significant lifespan and health span benefits of C60-EVOO or EVOO supplementation compared to untreated controls, both starting the treatment in adult or old age. Our results call into question the biological benefit of C60-OO in aging.
... Although there are several methods available to estimate the VOO stability, such as the oil stability index or active oxygen method, they use experimental conditions that are different from those found in actual storage (e.g., a temperature of 100 • C or more is applied). These differences in conditions modify the kinetics of the oxidation process and its effect upon VOO when it is stored under moderate conditions [14,17]. The control of the degradation process involves the monitoring of many parameters (peroxide value, free acidity, ultraviolet absorbance, organoleptic assessment, phenol content, etc.) with different time-trends in the course of the storage and informing about a particular aspect of quality, which makes it difficult to interpret quality with an overall perspective. ...
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The control of virgin olive oil (VOO) freshness requires new tools that reflect the diverse chemical changes that take place during the market period. Fluorescence spectroscopy is one of the techniques that has been suggested for controlling virgin olive oil (VOO) freshness during its shelf-life. However, a complete interpretation of fluorescence spectra requires analyzing multiple parameters (chemical, physical–chemical, and sensory) to evaluate the pace of fluorescence spectral changes under moderate conditions with respect to other changes impacting on VOO quality. In this work, four VOOs were analyzed every month with excitation–emission fluorescence spectra. The same samples were characterized with the concentration of fluorophores (phenols, tocopherols, chlorophyll pigments), physical–chemical parameters (peroxide value, K232, K270, free acidity), and sensory attributes (medians of defects and of the fruity attribute). From the six components extracted with parallel factor analysis (PARAFAC), two components were assigned to chlorophyll pigments and those assigned to tocopherols, phenols, and oxidation products were selected for their ability to discriminate between fresh and aged oils. Thus, the component assigned to oxidation products correlated with K270 in the range 0.80–0.93, while the component assigned to tocopherols–phenols correlated with the fruity attribute in the range 0.52–0.90. The sensory analysis of the samples revealed that the changes of these PARAFAC components occurred at the same time as, or even before, the changes of the sensory characteristics.
... Different spectroscopic techniques such as Fourier Transform Infrared (FT-IR) have now been extensively studied to analyze various chemical changes and correspond such changes with instrumental data using statistical tools importantly chemometrics. FT-IR is an analytical instrument based on the scanning of samples using infrared light to identify polymeric, chemical, and inorganic materials (Velasco & Dobarganes, 2002). The sample detects some of the infrared radiation and produces its molecular fingerprint in the form of a spectrum. ...
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The production of trans‐fats and chemical changes during the process of frying are serious public health concerns and must be monitored efficiently. For this purpose, the canola oil was formulated with different ratio of extra virgin olive oil and palm olein using D‐optimal mixture design, and the best formulation (67:22:11) based on free fatty acid (FFA) content, peroxide value (PV), and iodine value (IV) as responses was selected for multiple frying process. The data on FFA, PV, and IV along with Fourier transform‐infrared (FT‐IR) spectra were taken after each frying up to ten frying. The spectral data were preprocessed with standard normal variate followed by principal component analysis which is clearly showing the differentiation for various frying. Similarly, partial least square regression was applied to predict the FFA (0.37%–1.63%), PV (4.47–13.85 meqO2/kg), and IV (111.51–51.39 I2/100 g) which demonstrated high coefficient of determination (R2) 0.84, 0.83, and 0.81, respectively. It can be summarized that FT‐IR can be used as a novel tool for fast and noninvasive quality determination of frying oils. The current study was designed to make canola oil blends with different concentrations of olive oil and palm olein. These blends were optimized by D‐optimal Design using the oil stability parameters such as free fatty acid (FFA), peroxide (PV), and iodine values (IV). The optimized canola oil blend was further used for multiple frying, and FT‐IR spectral fingerprints were taken which is considered to be a rapid, non‐destructive, and environment‐friendly analytical tool for characterization of the chemical changes taken place due to the processing.
... Glutamine was detected in 324 all modern samples but not in historic samples, and its deamination products glutamate and 325 5-oxoproline were detected in higher concentration in all 17 samples, although at much 326 higher concentration in modern than historic samples. Oxidation, which is widely 327 documented in the degradation of oil paintings (Oakley et al. 2015) and food spoilage 328 (Velasco and Dobarganes 2002) also occurs in dental calculus. For example, the ratio of 329 cholesterol and its oxidation product 7-ketocholesterol was reversed between modern and 330 historic calculus, and kynurenin, an oxidation product of tryptophan that is known to 331 accumulate in archaeological bone over time (Cappellini et al. 2012) . ...
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Introduction Dental calculus is a mineralized microbial dental plaque biofilm that forms throughout life by precipitation of salivary calcium salts. Successive cycles of dental plaque growth and calcification make it an unusually well-preserved, long-term record of host-microbial interaction in the archaeological record. Recent studies have confirmed the survival of authentic ancient DNA and proteins within historic and prehistoric dental calculus, making it a promising substrate for investigating oral microbiome evolution via direct measurement and comparison of modern and ancient specimens. Objective We present the first comprehensive characterization of the human dental calculus metabolome using a multi-platform approach. Methods Ultra performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) quantified 285 metabolites in modern and historic (200 years old) dental calculus, including metabolites of drug and dietary origin. A subset of historic samples was additionally analyzed by high-resolution gas chromatography-MS (GC-MS) and UPLC- MS/MS for further characterization of polar metabolites and lipids, respectively. Metabolite profiles of modern and historic calculus were compared to identify patterns of persistence and loss. Results Dipeptides, free amino acids, free nucleotides, and carbohydrates substantially decrease in abundance and ubiquity in archaeological samples, with some exceptions. Lipids generally persist, and saturated and mono-unsaturated medium and long chain fatty acids appear to be well-preserved, while metabolic derivatives related to oxidation and chemical degradation are found at higher levels in archaeological dental calculus than fresh samples. Conclusions The results of this study indicate that certain metabolite classes have higher potential for recovery over long time scales and may serve as appropriate targets for oral microbiome evolutionary studies.
... Olive collection also has a profound effect on the quality of the resulting oil, with hand picking serving as the best technique. If the collection is delayed, the natural fall of the fruit takes place and a series of alterations deteriorate the quality of the oil, particularly its acidity 37 . Free oleic acid in the oil can increase if lipase enzymes act. ...
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Olive growing in Palestine plays an important role at social and economic levels. Nevertheless, the quality of olive oil produced in the country has not been fully addressed. This study examined oil content, peroxide values, acid values, fatty acid profile, and total phenolic content for old olive trees located in different climatic regions in Palestine during the years 2008-2010. Oil content was determined using both Soxhlet and Abencor systems. Acid and peroxide values were determined using standard methods. Total phenolic content was determined using the Folin-spectrophotometric method. Gas chromatography was used to analyze the main fatty acids found in olive oil e.g., palmitic, palmitoleic, stearic, oleic, linoleic. Different ratios indicating olive oil quality were also determined e.g., sum ratio of unsaturated fatty acids to the sum of saturated fatty acids; ratio between the sum of monounsaturated fatty acids to the sum of polyunsaturated fatty acids, and the ratio between the oleic to linoleic fatty acids. Significant differences were found between geographic regions for the overall studied oil parameters. Wide variation ranges were obtained for fatty acids in the different West Bank locations in the three years. The major fatty acids in the olive oil samples were found to be oleic, palmitic, stearic, linoleic, and palmitoleic acids. The oil samples were found to contain more oleic acid and less linoleic and linolenic acids that is, more monounsaturated than polyunsaturated fatty acids. Total phenolic content was found to range from 125.0-978.0, 207.4-763.8, and 103.0-747.6 mg/kg in 2008, 2009, and 2010, respectively. The acidity percentage was in the range of 0.10%-1.05%, 0.11%-1.29%, and 0.10%-1.91% in 2008, 2009, and 2010, respectively. Peroxide values ranged from 2.26-13.1, 2.94-14.95, and 2.49-17.21 in 2008, 2009, and 2010, respectively. graphical abstract Fullsize Image
... Processing and storage of oils in exposure to light can lead to the generation of a wide range of undesirable compounds, some of which are harmful to health because of their high toxicity, thereby altering their stability [47]. Among the components of essential oils, monoterpenes have been shown to degrade rapidly under the influence of visible light [48]. ...
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Essential oils (EOs) are widely recognized as efficient and safe alternatives for controlling pest insects in foods. However, there is a lack of studies evaluating the toxicological stability of botanical insecticides in stored grains in order to establish criteria of use and ensure your efficiency. The objective of this work was to evaluate the toxicological stability of basil essential oil (O. basilicum) and its linalool and estragole components for Sitophilus zeamais (Motschulsky) adults in corn grains by fumigation. The identification of the chemical compounds of the essential oil was performed with a gas chromatograph coupled to a mass selective detector. Mortality of insects was assessed after 24 h exposure. After storage for six (EO) and two months (linalool and estragole) under different conditions of temperature (5, 20, and 35 ◦C) and light (with and without exposure to light), its toxicological stability was evaluated. Studies revealed that the essential oil of O. basilicum and its main components exhibited insecticidal potential against adults of S. zeamais. For greater toxicological stability, suitable storage conditions for them include absence of light and temperatures equal to or less than 20 ◦C.
... The presence of pigments in plant oils is important and has a large effect on the stability of the oil. Several authors have mentioned the protective antioxidant effect of carotenoids in oils (Velasco and Dobarganes, 2002). Chlorophyll is a photosensitive pigment and hence prone to photo-oxidation, and therefore acts as a pro-oxidant in oils. ...
Article
The present research studied the oil content of Lallemantia peltata (Balangu) extracted by cold pressing method. Before extraction, the moisture contents of the seeds were adjusted to 0, 2.5, 5, 7.5 and 10% to evaluate its effect on the oil yield and its quality. Moreover, the physicochemical characteristics were measured during storage for up to 90 days. The optimum moisture content which gave the highest oil yield (33.5%) was 7.5%. Increasing of seed moisture content increased acid value, peroxide value and total tocopherols, whereas decreased total chlorophyll and carotenoid as well as oxidative stability. During storage, a significant increase (p < 0.05) was observed in the acid and peroxide values and γ-tocopherol content, while the α-tocopherol, δ-tocopherol, chlorophyll and carotenoid contents decreased. However, fatty acids and phytosterol composition did not significantly change by increasing moisture content and storage. Taken together, this study shows that the moisture content has a crucial influence on the oil yield and the quality of Balangu oil. Also, Balangu oil is rich in n-3 and n-6 acids and its nutritional profile is excellent and would be a good source of edible vegetable oil.
... Moreover, these compounds have the potential to prevent in vitro or in vivo oxidative processes [13]. Compared to refined types of olive oil, its virgin type contains higher amount of bioactive substances including polyphenolic compounds as a result of the elimination or considerable reduction of these compounds during the refining process [14]. ...
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This survey was conducted to evaluate the impact of virgin olive oil nanoemulsion (ONE) combined with ajowan (Carum copticum) essential oil (AEO) on quality of lamb loin under refrigerated condition. The treatments were control, ONE, ONE + 1% AEO, and ONE + 2% AEO. The treatments caused a delay in growth of mesophilic and psychrotrophic bacteria, Enterobacteriaceae, and lactic acid bacteria during chilled storage. The increasing rate of total volatile nitrogen content, lipid and protein oxidation, metmyoglobin formation, and color deterioration was more retarded in treatment groups. The treatments including ONE + 1% AEO and ONE + 2% AEO were more efficient than ONE alone to delay microbial flora growth, slow down oxidative processes, and improve color in the loins. According to the results of microbial, chemical, and sensory parameters, shelflife of lamb loins was 4 days in control, 8 days in ONE, and at least 16 days in ONE + 1% AEO and ONE + 2% AEO groups. In conclusion, combination of ONE and AEO is appropriate as natural preservative to extend the shelflife of lamb loins stored under chilled condition.
... These reactions are influenced by storage conditions, such as exposure to light, availability of oxygen and temperature, and by the composition of the oil itself. While linoleic and linolenic acids contribute to the oxidation of EVOO, minor substances, such as tocopherols and phenolic compounds, act as antioxidants (Velasco and Dobarganes 2002;Kotsiou and Tasioula-Margari 2015). ...
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This work aimed to evaluate changes in the profile of volatile compounds of extra virgin olive oils (EVOOs) from the states of Minas Gerais and Rio Grande do Sul (Brazil) during 8 months of storage. The samples of Koroneiki olive oils were characterized for fatty acid composition, acidity, peroxide value, and ultraviolet absorbance. Volatile compounds were identified and estimated by headspace solid-phase microextraction (HS-SPME), gas chromatography coupled to mass spectrometry (GC–MS), and flame ionization detection (GC-FID). The results obtained for fatty acid composition, free fatty acids, peroxide value, and ultraviolet absorbance are characteristic of extra virgin olive oils. The main volatile compounds identified at zero storage time were hexanal, (E)-2-hexenal, (Z)-3-hexenol, (Z)-3-hexenyl acetate, and hexyl acetate, all from the lipoxygenase pathway (LOX) and responsible for the characteristic green odor of EVOOs. The major compound found was (E)-2-hexenal, which also had the greatest decrease during storage. In the same period, (E)-2-heptenal, octanal, nonanal, and (E)-2-decenal, compounds associated to undesirable sensory characteristics in olive oils, were identified mainly in the eighth month of storage. Through PCA and fatty acid composition, the samples could be grouped according to their geographic origin.
... Disproportionation, as well as the cyclization process, occurs in monoterpenes at elevated temperatures [59]. Moreover, at high temperatures, compounds are formed through termination reactions [60]. Moreover, the higher concentration of humulene epoxide II (2.5% on the second day) makes difference to Garola from other populations. ...
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Valeriana jatamansi is an important temperate herb that is used in the pharmaceutical and essential oil industries. In India, this species is now on the verge of extinction due to the over-exploitation of its rhizomes from its natural habitat. It is hypothesized that the variations in bioactive compounds in its essential oil are very high among the wild populations as well as cultivated sources. Thus, this study was conducted to evaluate the chemical profiling of essential oil of four wild populations (Rupena, Kugti, Garola, and Khani) and two cultivated sources (CSIR�IHBT, Salooni), which were distilled at three consecutive days. The variation in oil concentration in roots/rhizomes was found significant (p ≤ 0.05), and the maximum value (0.35%) was registered with the population collected from Kugti and Khani. In essential oil, irrespective of population and distillation day, patchouli alcohol was the major compound, which ranged from 19 to 63.1%. The maximum value (63.1%) was recorded with the essential oil obtained from Garola’s population and distilled on the first day. The percentage of seychellene was abruptly increased with subsequent days of extraction in all the populations. The multivariate analysis revealed that the essential oil profiles of Rupena, Kugti, Garola, and CSIR-IHBT populations were found to be similar during the first day of distillation. However, during the second day, Rupena, Kugti, Khani, and CSIR-IHBT came under the same ellipse of 0.95% coefficient. The results suggest that the population of Kugti is superior in terms of oil concentration (0.35%), with a higher proportion of patchouli alcohol (63% on the first day). Thus, repeated distillation is recommended for higher recovery of essential oil. Moreover, repeated distillation can be used to attain V. jatamansi essential oil with differential and perhaps targeted definite chemical profile.
... It is believed to be associated with a relatively long life in good health. Olive oil is considered to be resistant to oxidation in comparison with other vegetable oils due to its low content of polyunsaturated fatty acids and the presence of natural antioxidants (Velasco et al., 2002 andAyton et al., 2012). ...
... Table (3) shows the minor components unsaponifiable matters% (UNSAP %), total polyphenolic contents, chlorophyll and carotenoids (in mg/kg) and organoleptic attributes (fruity, bitter and punent) of the olive oils in different fertilizing treatments. The bioactive components of extra virgin olive oil are resulted from a number of variables acting before extraction (such as variety, environmental, climatic, soil and cultivation conditions, olive ripeness and olive healthy) and during olive oil extraction and storage [69]. ...
Article
The difference in the aroma composition of cold‐pressed and roasted peanut oils was investigated. There were 28 and 75 odorants with flavour dilution (FD) factors between 1 and 512 in cold‐pressed and roasted peanut oils, respectively. Fifty‐nine odorants were newly identified in peanut oils. Ten key odorants with odour activity value (OAV) ≥ 1 were identified in cold‐pressed peanut oil, of which hexanal (OAV = 1,288, green), (E,E)‐2,4‐decadienal (OAV = 370, earthy and fried fat) and α‐pinene (OAV = 34, woody) were the most important contributors to the overall aroma of cold‐pressed peanut oil. 2,3‐Pentanedione (OAV = 5,054, buttery), 2‐methoxy‐4‐vinylphenol (OAV = 326, smoky), 2,5‐dimethylpyrazine (OAV = 160, roasted and nutty) and 2‐methylpyrazine (OAV = 92, roasted and nutty) were the most important contributors among the 26 key odorants to the aroma of roasted peanut oil. Roasting peanut seeds induced apparent changes in the formation of aromatic heterocycles, loss of terpenes and increase in lipid oxidation odorants in peanut oil. This study would provide important practical applications in aroma regulation and process optimisation of peanut oil. Comparison of the key aroma‐active compounds that contributed to the different aroma perception of the cold‐pressed and roasted peanut oils by means of molecular sensory science.
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Zeytinyağının en az işlem görmüş çeşidi olan natürel sızma zeytinyağı (NSZY), içerdiği yüksek miktardaki antioksidanlar ve tekli doymamış yağ asitleri nedeniyle en sağlıklı yağlardan birisi olarak kabul edilmektedir. Ancak soğuk tüketilmesi gerektiğine inanıldığı için, bu yağ yemeklerde ve kızartmalarda tercih edilmemektedir. Bu çalışmada, kısa ve uzun süreli ısıl işlemin NSZY’nin kalitesi üzerindeki etkileri, pişirme tipi zeytinyağı olarak bilinen riviera zeytinyağı (RZY) ile karşılaştırmalı olarak Azaltılmış Toplam Yansıma-Fourier Dönüşüm Kızılötesi (ATR-FTIR) spektroskopisi kullanılarak araştırılmıştır. Yağ örnekleri günlük 6 saatlik periyotlarla, 24 saat boyunca fritözde ısıtılmış (180 oC) ve bu yağlardan kısa süreli ısıl etki için 1/2., 1. ve 2. saatin sonunda, uzun süreli etki için 6., 12., 18. ve 24. saatin sonunda alınan örnekler incelenmiştir. Sonuçlar, her iki yağda da ısıl işlemin cis yağ asitlerinin miktarında azalmaya, trans yağ asitlerinin ve birincil ve ikincil oksidasyon ürünlerinin miktarında artışa sebep olduğunu göstermiştir. Bu değişikliklerin çoğu NSZY’de RZY’den daha geç başlamış ve kısa süreli ısıl işlem boyunca daha düşük boyutlarda ortaya çıkmıştır. Uzun süreli ısıtmada ise NSZY’de meydana gelen değişimlerin RZY’den daha büyük boyutlarda olduğu gözlenmiştir. Bu sonuçlar kısa süreli ısıl işlem için NSZY’nin RZY’den daha dayanıklı olduğunu ve yemeklerde ve tekrarlı olmayan kızartmalarda daha sağlıklı bir alternatif olarak kullanılabileceğini ancak uzun süreli ısıl işlemler için tercih edilmemesi gerektiğini göstermiştir. Ayrıca bu çalışmanın sonuçları, yağların oksidatif stabilitesinin ATR-FTIR spektroskopisi ile herhangi bir ön işleme gerek duyulmaksızın hızlı bir şekilde analiz edilebileceğini göstermiştir.
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At olive oil industrial extraction, water addition is a practice overcoming the formation of thick pastes. The effect of water addition (0 to 6.2%, kg added water/kg olives), during the industrial milling of cv. Arbequina olives, on the oils’ chemical-sensory quality, was evaluated. Despite the extra virgin olive oil classification, compared with the water incorporation (1.2-6.2%), extraction without water addition resulted into oils that showed less primary oxidation (lower peroxide values and K232), greater total phenolic content (+12-22%) and higher oxidative stability (+22-31%). No water addition increased the oils secoiridoids content (+5-13%), mainly oleacein (+27-79%). Oils extracted without water addition had a more intense ripe fruity sensation (≥ +11%) but lower fruit intensities (at least −4%). Thus, the quality and stability of the cv. Arbequina oils can be favoured if extracted without adding water during the olives industrial milling.
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Fats are an important part of diet, but not all lipids have the same structure and chemical properties. Unsaturated fatty acids have one or more double bonds in their structure and can be monounsaturated or polyunsaturated, respectively. Most vegetable oils, such as olive oil and corn oil, contain significant amounts of these fatty acids. The presence of double bonds in the molecule of a fatty acid constitutes vulnerable sites for oxidation reactions generating lipid peroxides, potentially toxic compounds that can cause cellular damage. In response to this oxidative damage, aerobic organisms have intracellular enzymatic antioxidant defense mechanisms. The aim of the present investigation was to study comparatively the effects of control liquid diets, of a defined composition, containing olive oil or corn oil as a lipid source respectively of monounsaturated and polyunsaturated fatty acids, on the oxidative metabolism of rats. Rats were divided into three groups which received a control animal feed diet (A.F.), olive oil liquid diet (O.O) and corn oil liquid diet (C.O) for 30 days. It was observed that the activity of the antioxidant enzymes superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GPx), increased in the liver and white fat tissue of rats fed with olive oil when compared to the corn oil group. However, in brown fat tissue and blood cells, the enzyme activities showed a tendency to decrease in the olive oil group. In addition, the effect of olive oil and corn oil on several glucose metabolism parameters (pyruvate, lactate, LDH, acetoacetate and beta-hydroxybutyrate) showed that corn oil impairs to a greater extent the cellular metabolism. All these results helped in concluding that some body tissues are more adversely affected than others by the administration of corn oil or olive oil, and their antioxidant defenses and cellular metabolism respond differently too.
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As the major oxidized triglycerides (ox-TGs), epoxy triglyceride is one of the toxic polar components from deep frying oil. However, the conventional methods are difficult to separate epoxy triglyceride from other ox-TGs due to their similar molecular and structures. To address the problem, a novel magnetic solid-phase extraction approach based on a surface molecularly imprinted polymers was developed. The polymers coated on Fe3O4 nanoparticles (Fe3O4@MIPs) were synthesized and used as highly selective sorbents for capture epoxy triglyceride from deep frying oil. They have high adsorption capacity (58.3 mg/g), stable equilibrium adsorption time (60 min) and excellent specificity. This method had a satisfactory linear relationship in the range of 0.2–10 mg/L (R² = 0.997), and the detection limit of epoxy triglyceride was 0.0599 mg/L. Results indicated that Fe3O4@MIPs could not only specifically separate epoxy triglycerides, but also provided a potent idea for the separation of other ox-TGs from deep frying oil.
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Metabolomic fingerprinting of virgin olive oil (VOO) by ¹H-NMR spectroscopy was used to study its stability during storage simulating normal shelf life conditions during its commercialization. A representative set of VOOs covering the full range of possible chemical compositions were exposed to light (500 lux for 12h/day) at 25 ºC for 12 months or stored in the dark at 25 ºC, 30 ºC and 35 ºC for 24 months. Multivariate data analysis of the ¹H-NMR spectra of the oil samples provided classification models to evaluate VOO freshness and to verify the light exposure of the VOO during storage, as well as regression models to determine VOO storage time and tentatively the best before date of a fresh VOO. These predictive models disclosed the chemical compounds responsible for the compositional changes in VOO due to hydrolytic and oxidative degradation taking place during its storage, and confirmed that light and increasing temperature enhance these processes. The presence of characteristic resonances of hydroperoxides (primary oxidation products) and the decrease of ¹H signals assigned to phenolic compounds, mainly secoiridoid derivatives, and other minor compounds such as fatty acids, squalene and native (E)-2-hexenal present in fresh VOO revealed its oxidative degradation. Further, the emergence of low intensity ¹H signals of saturated aldehydes meant that the secondary oxidation process has started at a low rate and yield. Moreover, the decrease of the ¹H signals of triacylglycerides and sn-1,2-diacylglycerides, and the increase of sn-1,3-diacylglycerides indicated that hydrolytic degradation of VOO and diacylglyceride isomerisation was occurring. ¹H-NMR fingerprint of VOO together with pattern recognition techniques afford relevant information to assess the quality of VOOs taking into consideration legal, sensory and health-promoting aspects.
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Volatile compounds are chemical species responsible for the distinctive aroma of virgin olive oil. Monovarietal olive oils have a peculiar composition of volatiles, some of which are varietal descriptors. In this paper, the total phenolic content (TPC), fatty acid composition, volatile compounds, and sensory profile of monovarietal olive oils from four Dalmatian most common olive cultivars—Oblica, Lastovka, Levantinka, and Krvavica—were studied. The volatile composition of olive oils was analyzed using headspace solid-phase microextraction with gas chromatography/mass spectrometry. The highest mean TPC value was measured in Oblica and Krvavica oils (around 438 mg/kg). The difference among cultivars for fatty acids composition was detected for C16:1, C17:0, C18:1, C18:2, and the ratio C18:1/C18:2. Krvavica oils showed clear differences in fatty acid composition compared to oils from other cultivars. The most prevalent volatile compound in all oils was C6 aldehyde E-2-hexenal, with the highest value detected in Levantinka oils (75.89%), followed by Lastovka (55.27%) and Oblica (54.86%). Oblica oils had the highest value of Z-3-hexen-1-ol, which influenced its characteristic banana fruitiness, detected only in this oil. Lastovka oils had the highest amount of several volatiles (heptanal, Z-2-heptenal, hexanal, hexyl acetate), with a unique woody sensation and the highest astringency among all studied cultivars. Levantinka oils had the highest level of almond fruitiness, while Krvavica oils had the highest level of grass fruitiness.
Article
Flaxseed oils contain significant amounts of unsaturated fatty acids and, consequently, are susceptible to oxidative process. Additionally, inadequate conditions of storage result in the intensification of unfavorable processes. This problem is becoming more and more serious due to the high intensity of illumination of shop display cases and storage rooms, as well as the exposure to sunlight. Although literature data suggests that light may be an even more important oxidizing agent than oxygen, experiments are mainly focused on the oxidation progress in oils from varied raw materials or the changes in oil characteristics under different storage conditions. The aim of the study was to investigate the effect of the initial state of 30 commercial cold-pressed flaxseed oils on oxidative stability and oxidation product formation during storage under simulated store conditions (one-month at ambient temperature with light exposure). The oil quality was analyzed qualitatively (characteristic quality values, content of conjugated fatty acids, induction period, color parameters) and quantitatively (content of water and bioactive compounds, fatty acid composition). Oxidation progress in the oils was monitored by the characteristic quality values, content of conjugated fatty acids and color parameters. It was shown that commercially available cold-pressed flaxseed oils were generally good quality with similar color parameters and fatty acid composition, but mostly varied in terms of carotenoids, chlorophylls and phenolic compounds. Storage with light exposure caused the deterioration of the oil quality, and at least a 1.0-fold increase in acid and anisidine values and at least a 24.8-fold increase in peroxide value were determined. Also, the color of all oils changed after storage, and the calculated total color differences (ΔE) were in the range of 0.2–8.7. The results highlighted that the formation of oxidation products in flaxseed oil during storage in light resulted mainly from its initial quality indices. In turn, the induction period tested by Rancimat was dependent on the fatty acid percentages and total phenolic compound content. In conclusion, the Rancimat test is a poor indicator of the oxidative stability of oils under storage at ambient temperature with light exposure.
Chapter
Lipid oxidation is the principal cause of nonmicrobiological deterioration of food. It can occur through autoxidation (oxidation with ³O2), photooxidation (oxidation with ¹O2) and enzymatic oxidation. Both autoxidation and photooxidation occur with the formation of hydroperoxides as primary products and their decomposition to secondary products, which are mostly low-mass aldehydes, ketones, alcohols, acids, esters, epoxides, and hydrocarbons. Singlet oxygen reacts directly with the unsaturated fatty acids while ³O2 needs an initiation step. Many factors influence lipid oxidation, such as the nature of the lipids, nature and composition of the food matrix, physical structure and physicochemical characteristics, availability and type of oxygen, transition metals, light, temperature, water activity, other food components, and additives, processing and storage conditions. Strategies to minimize lipid oxidation include vacuum packaging or controlled atmosphere, low-temperature storage, encapsulation of sensitive added compounds, addition of antioxidants. Lipid oxidation frequently limits the shelf-life of foods with the development of unpleasant rancid odor and taste. Negative effects on human health include loss of nutrient value and functionality and accumulation of compounds potentially toxic to humans.
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Commercialization of extra virgin olive oil (EVOO) requires a best before date recommended at up to 24 months after bottling, stored under specific conditions. Thus, it is expected that the product retains its chemical properties and preserves its ‘extra virgin’ category. However, inadequate storage conditions could alter the properties of EVOO. In this study, Arbequina EVOO was exposed to five storage conditions for up to one year to study the effects on the quality of the oil and the compounds responsible for flavor. Every 15 or 30 days, samples from each storage condition were analyzed, determining physicochemical parameters, the profiles of phenols, volatile compounds, α-tocopherol, and antioxidant capacity. Principal component analysis was utilized to better elucidate the relationships between the composition of EVOOs and the storage conditions. EVOOs stored at −23 and 23 °C in darkness and 23 °C with light, differed from the oils stored at 30 and 40 °C in darkness. The former was associated with a higher quantity of non-oxidized phenolic compounds and the latter with higher elenolic acid, oxidized oleuropein, and ligstroside derivatives, which also increased with storage time. (E)-2-nonenal (detected at trace levels in fresh oil) was selected as a marker of the degradation of Arbequina EVOO quality over time, with significant linear regressions identified for the storage conditions at 30 and 40 °C. Therefore, early oxidation in EVOO could be monitored by measuring (E)-2-nonenal levels.
Article
Tomato seeds, which are the byproducts of tomato paste processing, were used to obtain tomato seed oil using two different extraction methods: cold press extraction (CPE) and enzymatic assisted aqueous extraction (EAAE). To maximize oil amount, the experimental parameters of those two methods were optimized separately by response surface methodology. The optimized methods were used to evaluate their quality characteristics. The maximum oil amounts for tomato seed oil using CPE and EAAE were found as 12.80% and 9.66%, respectively. These obtained results present important information for the determination quality characteristics including the physical, chemical, microbiological, and bioactivity properties of tomato seed oil in both extraction methods used. The comparison of two methods shows that they are both ecology friendly extraction methods. It also helps to a great extend to evaluate quality characteristics and bioactivity properties of tomato seed oil. Therefore, tomato seed oils extracted by two methods are promising for future usage as functional food. This manuscript will comprise the basis of our future studies analyzing the new compounds obtained from agro‐food waste.
Article
Ghavoot is an Iranian traditional food product that prepared by a combination of several types of plant seeds mixed with sugar. The lack of appropriate packaging caused Ghavoot exposed to environment conditions, which leads to oxidation of this product and reduce its nutritional value and marketability. In this study, different types of packaging materials including nylon, the Polyester/ Aluminum/ polyethylene (PET/AL/PE) and the Polyester /Aluminum / Low-Density Polyethylene (PET/AL/LDPE) with different concentrations of oxygen inside the packaging (zero, 5 and 21%) were used to maintain quality properties of Ghavoot. The results showed that samples stored in the PET/Al/LDPE packaging under vacuum, had fewer moisture changes during storage compared with other treatments, as a result, the least changes in the color parameters of Ghavoot occurred. Increasing the concentration of oxygen inside the packaging resulted in higher peroxide, anisidine and totox values as well as the higher total acidity of the Ghavoot’s oil. Keeping Ghavoot in the three-layer PET/Al/LDPE pouches under vacuum condition, caused the lipid oxidation to be delayed during the storage. Results of sensory properties showed that increasing the oxygen concentration inside the packaging caused the average score for product flavor to decrease as a result of rancidity development.
Article
Volatile compounds are responsible for the valued aroma of extra virgin olive oil (EVOO). Among them, it is worth emphasizing the relevance of C6 and C5 volatiles formed in the lipoxygenase pathway. These compounds are direct indicators of positive attributes such as fruity, sweet, green or ripeness. Here, we have analyzed the volatile profile of 193 EVOOs obtained in two consecutive seasons to evaluate the cultivar influence and the interannual variability. We were particularly targeted at C6 and C5 volatiles to discriminate between two clusters of cultivars (Cluster 1: ‘Arbequina’, ‘Coratina’ and ‘Frantoio’; Cluster 2: ‘Cornicabra’, ‘Hojiblanca’, ‘Picual’ and ‘Picuda’). Thus, trans-2-hex-enal and trans-2-hexen-1-ol were specially enriched in EVOOs from Cluster 1, while C5 volatiles, 1-penten-3-ol and 1-penten-3-one, and cis-3-hexen-1-ol were more concentrated in Cluster 2 EVOOs. The cultivar influence on one of the main pathways contributing to the EVOO aroma is proved.
Article
Vegetable oils are key ingredients of the human diet, as they are widely used for cooking and as ingredients in many processed foods. However, processing may lead to their oxidation and result in an array of negative outputs such as the development of undesirable organoleptic characteristics (e.g. off-flavors and texture alteration), a decrease in nutritional value, shelf-life and even in the formation of toxic compounds. Many strategies for improving oil stability have been developed such as the use of natural and synthetic antioxidants, and more recently the use of encapsulation techniques. It has many beneficial effects due to the barrier effect it establishes between the oil and the environment; this not only protects the oils against chemical reactions and physical changes but maintains their biological and chemical characteristics. This review is divided into three parts. In the first, the mechanisms of oil oxidation and the factors responsible for oxidation are summarized. In the second part, the consequences of oxidation in oil quality and the production of potentially harmful decomposition compounds are reviewed. Finally, the addition of antioxidants and encapsulation techniques are also compiled as strategies to improve oils’ oxidative stability.
Article
Berry seeds are rich source of high quality oil containing valuable compounds such as polyunsaturated fatty acids and therefore, have been gaining increasing significance as potential source of nutrients for food, cosmetic or pharmaceutical industry. Supercritical carbon dioxide extraction of seeds was performed, for which oxidative stability analyzes and determinations of fatty acids, selected microelements and toxic metals were carried out. An attempt was made to evaluate unclassified scCO2 oil extracts from berry seeds, taking into account the lack of legislative documents specifying the required contents of metals and biologically active ingredients. The obtained extracts are products with the consistency of liquid oil. The total fatty acid content range from 59 % to 98 %, with unsaturated fatty acids predominating and very good n-3/ n-6 fatty acids ratio. The analyzed samples were taken systematically from one extraction sequence also determining the acid and the peroxide values in subsequent fractions.
Article
The influence of extraction system and both storage time and conditions on quality characteristics of ‘Moroccan Picholine’ virgin olive oil (VOO) was investigated. Results from ANOVA analysis showed that the storage time largely affected the most of VOO characteristics (peroxide value, K270, chlorophylls, carotenoids and total phenols). The K232 variability was due to both extraction system and storage time. The free fatty acids were mostly dependent on extraction system. Moreover, we observed that increasing the storage time provoked a slight but significant accumulation in free fatty acids and higher values for oxidation indices. The highest increment rates were recorded in the first months of storage for the peroxide value and from the 6th month onwards for K232 and K270. For carotenoids, chlorophylls and total phenols, we noticed dramatic losses after twelve months of storage. Among extraction systems, the two-phase centrifugation system kept the good VOO quality and displayed the lowest values of free fatty acids, peroxide value, K232, and K270, and the greatest records for carotenoids and total phenols contents. It has been also revealed that VOO stored in the dark at 4 °C maintained the best quality indices. Exposure of VOO to light and ambient temperatures caused substantial deterioration in quality parameters. Principal component analysis (PCA) explained about 91% of total variability: 77 and 14% for PC1 and PC2, respectively. Storage time fitted the variability of PC1, while extraction system caused the variability on PC2. Correlation studies showed a clear association of oxidation indices with antioxidant compounds.
Chapter
In traditional medicine, botanicals and medicinal plants in their natural and processed form are widely used [1] due to their medicinal and antioxidant properties. Numerous analytical methods have been developed for the analysis of chemical composition of medicinal plants extracts like gas chromatography (GC), mass spectrometry (MS), thin layer chromatography (TLC), UV spectrometry, and high performance liquid chromatography (HPLC). All these methods are precise but expensive, time-consuming and require many reagents. As an alternative, near infrared spectroscopy (NIRs), as a simple, selective, and environmentally friendly method [2], can be used. NIR spectroscopy is a non-destructive measurement method that allows intact measuring, without any additional sample preparation or pre-treatment. Use of spectroscopy in the near infrared region allows a wide range of applications in the food chain production, from control of raw materials to intermediary and final products [3] in order to provide a quality guarantee for consumers. NIR spectroscopy is based on the electromagnetic absorption in the near infrared region. Spectral analysis has to be assisted with various chemometric techniques, such as multiple linear regression analysis (MLRA), principal component analysis (PCA) and partial least squares regression (PLSR) [4]. Chemometric techniques and chemometric modelling have become an integral part of spectral data analysis which also includes pre-processing of NIR spectra. The pre-processing objective is removal of physical phenomena in the spectra in order to improve the subsequent multivariate regression, classification model or exploratory analysis [5]. In this work, most widely used pre-processing techniques including (i) scatter-correction methods and (ii) spectral derivatives are explained through analysis of spectra of dried medicinal plants collected during the size reduction process (milling), as well as during analysis of the kinetics of the solid-liquid extraction process using water as a solvent [6]. In order to identify patterns in large set of data and express the data to highlight similarities and differences among them, PCA was used. PCA presents the pattern of similarity of the observations and the variables by displaying them as points in maps [7]. PLS regression was used to predict or analyse a set of dependent variables from a set of independent variables or predictors. The predictive ability of a PLS model is expressed as one or more statistical measures. Which parameter should be used is described by R-Squared Coefficient, Ratio of standard error of Performance to standard Deviation (RPD) and Range Error Ratio (RER).
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The quenching effect of α-, γ- and δ-tocopherols on the methylene blue sensitized photo-oxidation of methyl linoleate was investigated, and the 1O2 quenching ability of tocopherols was determined. The 1O2 quenching rate constants for α-, γ- and ii-tocopherols in ethanol were estimated to be 2.6 ×108 M-1 sec-1, 1.8 ×108 M-I sec-1 and 10 ×108 M-1 sec-1, respectively. And the rate constants for the chemical reaction between each tocopherol and 1O2 were 6.6 × 108 m-1 sec-1, 2.6 × 106 M-1 sec-1 and 0.7 × 106 M-1 sec-1 for α-, γ- and δ-tocopherols, respectively. The results show that a-tocopherol is the most effective compound toward 1O2 among the three tocopherols. The photooxidation of each tocopherol produced two peroxides which, after chemical reduction, were identified to be tocopherol hydroquinone by gas chromatography-mass spectrometry analysis. The photooxidation mechanism of these tocopherols was assumed to be different from that of autoxidation.
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Les Bu/eurs anI étudié nnfJuence du manganèse et du nickeJ sur J'oxydation des huiles d'olive vierges. Des quantités crois-santes de sels organo-mètalliques de Mn et de Ni ont ètè ajou-tées à une huife d'olive vierge .. les échanlillons ainsi obtenus ant été conservés à température ambiante et sous Jumière diffuse. L 'effet catalytique des mètaux cansidèrès sur l'oxydation a ètè ètudiè par la dètermination des indices habituels qui décri-vant ce processus, Bussi qua par l'évaluation des paramètres qui dèfinlssent la flaveur et la cauleur. Les changements les plus significatifs résultant de cette addition du Ni et Mn ani été observés par cas dernières mesures.
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A staple food for thousands of years for the inhabitants of the Mediterranean region, olive oil is now becoming popular among consumers all over the world. Olive oil differs from other vegetable oils because it is used in its natural form and has unique flavor and other characteristics. More and more research suggests its healthful benefits including reduced risk of coronary heart disease. Olive Oil is a compact and readable text on the most important aspects of chemistry, technology, quality, analysis and biological importance of olive oil. The topics selected have been developing rapidly in recent years, and will provide the reader with a background to address more specific problems that may arise in the future. Readers can expect more contributors and chapters in the 2nd edition, as well as a glossary.
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During the 1993-94 season, a total of 1,003,351 Kg. of olive fruits (Olea europaea, cvs. Blanqueta y Villalonga) were stored in a cool room at 5 °C until a maximum time of 18 days. The virgin olive oil obtained from these fruits showed physical, chemical and sensorial indices inside the limits established for the «extra» virgin olive oil. The cool-storage of the olive fruits made possible a maximum yield in the processing machinery for 8 weeks without an appreciable lost of quality on the virgin olive oil obtained. It allows a better amortisation of the disposable equipments and, requiring the distribution of the fruit in boxes, contributes to the rationalisation of the olive fruit postharvest manipulation.
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Three new secoiridoids have been isolated from the leaves of Olea europaea along with the previously reported. The compounds were identified by spectral means.
Article
The quenching effect of α-, γ- and γ-tocopherols on the methylene blue sensitized photooxidation of methyl linoleate was investigated, and the 1O2 quenching ability of tocopherols was determined. The ¹O2 quenching rate constants for α-, γ- and γ-tocopherols in ethanol were estimated to be 2.6 × 10⁸ M-1 sec-1, 1.8×10⁸ M-1 see-' and 10×10⁸ M-1 sec-1, respec tively. And the rate constants for the chemical reaction between each tocopherol and 102 were 6.6×10⁸ M-1 sec-1, 2.6×10⁸ M-1 sec-1 and 0.7×10⁸ M-1 sec-1 for α-, α- and γ-tocopherols, respectively. The results show that α-tocopherol is the most effective compound toward 102 among the three tocopherols. The photooxidation of each tocopherol produced two peroxides which, after chemical reduction, were identified to be tocopherol hydroquinone by gas chromatography-mass spectrometry analysis. The photooxidation mechanism of these tocopherols was assumed to be different from that of autoxidation. © 1977, Japan Society for Bioscience, Biotechnology, and Agrochemistry. All rights reserved.
Article
Since the first edition of Deep Frying was published in 1996, there have been many changes to the U.S. Dietary Guidelines and nutritional labeling laws, and improvements in frying technology and practices have made a significant impact on the industry. This book will cover everything you need to know to create fat and oil ingredients that are nutritious, uniquely palatable and satisfying.
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A new method has been developed to estimate the stabilising activity of synthetic and natural food additives at frying. Non-refined and refined vegetable fats and oils were heated at a temperature of 170 degreesC after adding water-conditioned silica gel for two hours. The degraded products were measured to assess the oil stability at frying temperature. The determination of polymeric triglycerides by size exclusion high-pressure liquid chromatography (HPLC) was carried out for the estimation of the oxidative heat stability of vegetable fats and oils. Tocopherols, various tocopherol esters and phytosterol fractions, phenolic compounds, like quercetin, oryzanol, ferulic acid, squalene, butyl hydroxytoluol (BHT), butyl hydroxyanisol (BHA), and other compounds, like ascorbic acid 6-palmitate and gallates, are added to refined sunflower and rapeseed oil and their efficacy determined. Both linoleic and oleic rich oils gave comparable results for the activity of the various compounds. alpha -tocopherol, tocopherol esters, and BHA have low effects at frying temperature. Ascorbic acid 6-palmitate and some phytosterol fractions were found to have the greatest antioxidant activity. Corn oil was more stable than soybean oil and rapeseed oil better than olive oil. It was also observed that non-refined oils proved to have a better stability at elevated temperature than refined oils. The results show that the stability of the vegetable oils at frying temperature is a function of more than just the fatty acid composition. There is evidence which supports a co-relationship between the unsaponifiable matter content and oxidative stability. It is believed that a radical peroxidation mechanism predominates at lower temperatures. When a large volume of oil is heated in a fryer and the oxygen supply is poor, non-radical reactions such as elimination (acid catalysed dehydration) or nucleophilic substitution take place.
Article
During frying, it is well-known that a wide variety of chemical reactions results in the formation of new compounds that differ in molecular weight and polarity. This chapter provides a summary of the main groups of alteration compounds formed during frying, resulting from the oil or fat being exposed to high temperatures in the presence of air and moisture. Hydrolysis occurs due to the presence of moisture in the food. This involves breaking ester bonds and releasing free fatty acids, monoglycerides, and diglycerides. These compounds have higher polarity and lower molecular weight than the original Triglycerides (TG). While diglycerides, monoglycerides, and fatty acids likewise originate in the stage before intestinal absorption and hence have no relevance from a nutritional point of view, non-volatile alteration products do modify the nutritional properties of oils and fats. Therefore, the evaluation of the complex mixture of non-volatile compounds, ingested as a part of fried food, and the understanding of its dependence on the main variables of the frying process are a subject of great interest not only for processors and food technologists, but also for nutritionists and consumers. The chapter addresses the major non-volatile alteration compounds in used frying oils and fats, oxidized monomeric, dimeric, and higher oligomeric TG, also named oxidized monomers, dimers, and polymers. It discusses their formation and the analytical techniques used for their quantitation, as well as their occurrence in used frying fats.
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In this paper the effects of the enzymatic treatment on the quality and composition of vegetable edible oils are revised. Stability and refinability related aspects of oils from seeds, olive and other fruits are presented, so as an organoleptic valoration of the olive oil. Oils from enzyme aided processes show composition and characteristics similar to the ones from oils obtained from raw materials.
Article
Polyphenols influence the oxidative stability and sensory quality of virgin olive oil, Studies from the last 30 years are reviewed and the most significant findings are presented. Information is given on the main phenolic compounds detected and identified in olive fruit and oil. In recent years powerful analytical techniques (GC-MS, HPLC-MS, NMR) have been used to investigate the complex nature of olive oil polyphenols, Tyrosol, hydroxytyrosol, oleuropein aglycon and their derivatives with a non-phenolic acid and elenolic acid in free or esterified forms are the main components of the water-methanol extract of virgin olive oil, known as the polar fraction. Total phenol content as determined colorimetrically correlates well with the oxidative stability of the oil. The contribution of individual phenols to oil stability has not been fully investigated. There is still more to be known about the importance of the presence of phenolic components to the sensory quality of the oil.
Article
Certain phospholipids, in particular phosphalidyl ethanolamine, have been shown to exert svnergistic effects with the primary antioxidant tocopherols in inhibiting autoxidation of polyunsaturated fatty acids in model systems based on both lard and soyabean oil. The effect is specific to the chemical class of phospholipid, being less marked with phosphatidyl choline and non-existent, or even negative, with phosphatidyl inositol. Stability evaluations have been in the temperature range 100-140°C, making use of accelerated tests involving peroxide value measurement and automated oxygen absorption. Synergistic efficiency is a function of phospholipid concentration. For a given substrate and tocopherol concentration, induction periods increase approximately linearly over the range 0-1.0% phosphatidyl ethanolamine.
Article
Polymeric compounds stand out as the most representative group of compounds among those formed during the frying process. The main routes for formation of nonpolar and polar dimers originating during the first step of polymerization reactions are briefly reviewed. Also, the techniques applied for determination of dimers and polymers in used frying fats are described with special emphasis on the use of size-exclusion chromatography. Finally, the influence of the frying variables modifying the amount and type of polymers formed as well as the levels of polymeric compounds found in used frying fats from different origins are discussed.
Article
This paper is concerned with the industrial frying process and in particular the role of the frying oil and the influence this has on the food. Attention is drawn to various factors that can adversely affect the quality of the frying oil. In this paper the term «frying oil» is used. Other publications may refere to frying fat or frying shortening. As these are all used well above their melting points, and are fully liquid, the term oil is preferred by the present author, there being no quality difference between the products so named. The quality of oil or fat used for frying is of paramount importance with regard to the quality of the fried food. The amount of oil absorbed in different fried foods varies; battered fish or chicken absorb about 15% frying oil, while breaded fish or chicken absorb up to 20% frying oil. The amount of oil absorbed by doughnuts varies from 15-20% of their final weight. This is, of course, in addition to the shortening used in preparation of the dough, giving a final oil/fat content of up to 30%. Standard or traditional potato crisps absorb the highest quantity of oil, and up to 35 or 40% of the final food may be frying oil. Recently, modern technology has been introduced to produce low-fat crisps, but these still have about 20% absorbed oil. It should therefore be remembered that the fat used for frying becomes part of the food we eat. The most important aspect of industrial frying is therefore the frying oil, and in surveying factors that affect frying oil quality, this paper reviews (a) oil properties and composition; b) transport, packaging and storage of oil; c) the nature of the food fried and its interaction with the frying oil; d) the frying equipment and the process of frying; and e) the evaluation of the quality of the frying oil during use. Each of these factors is important in its own way, and it is of no advantage to concentrate on one or two, or even three, of these aspects without appreciating that there may be additional influences on the quality of the frying oil, and thus the fried food.
Article
Crude palm oil (CPO) (Elaeis guineensis) can serve as a promising source of β-carotene in developing countries where vitamin A deficiency is prevalent. Indigenously produced CPO has been evaluated for its chemical, nutritional and toxicological properties, and found to be nutritionally adequate and toxicologically safe for human consumption. This paper reports the acceptability of CPO, stability of β-carotene in CPO products and its bioavailability in school children. CPO was found to be well accepted in preparations where its yellow/orange colour blended well with the natural colour of certain Indian food items. 1:1 blend of CPO and ground nut oil (GNO) preparations were better accepted. Total carotene in CPO estimated spectrophotometrically was 540 μg/g and β-carotene (estimated by reverse phase HPLC) was 370 μg/g, approximately 70% of total carotenes. Cooking losses of β-carotene in a range of products were observed to be 22 to 30% and total carotenes 24 to 32%. Repeated frying using the oil five times consecutively, resulted in a steep drop followed by a total loss of β-carotene accompanied by alteration of its physico-chemical and organoleptic properties. Bioavailability of CPO β-carotene in children was assessed by feeding foods prepared in CPO, in comparison with vitamin A. The modified relative dose response (MRDR) test, was implemented for assessing the vitamin A status.
Article
Shelf-lives of sunflower oil and olive oil were estimated using an Accelerated Shelf-life Testing (ASLT) method and these were compared with the values in long term storage. In addition, the effect of type, oxygen permeability, and transparency of the packages on the shelf-lives of oils were investigated. The determinations were based on the oxidative stability of oils by measuring their peroxide values. The limiting peroxide value corresponding to the end of shelf-life was obtained from the FAO/WHO standards. The shelf-lives of sunflower and olive oil samples in retail store conditions were estimated as 10.6 and 20.8 mo, respectively. Storage lives of sunflower oil in polyethylene tere-phthalate (PET), clear glass and colour glass bottles under a 10 W fluorescence lamp were 10.4, 11.1 and 11.8 mo at 10°C, and 4.8, 5.1 and 6.5 mo at 20°C, respectively. Long term storage lives of olive oil in PET, clear and coloured glass were 17.5, 17.8 and 18.3 mo at 10°C, and 8.0, 8.4 and 8.7 mo at 20°C, respectively. These long term storage lives were then compard with the ASLT results obtained from the modified active oxygen method using a simple shelf-life plot approach.
Article
The effect of sterols on the oxidation of a triglyceride mixture, similar in composition to olive oil, has been studied at 180°C. Δ5-Avenasterol and fucosterol are effective as antioxidants, whilst other sterols, including cholesterol and stigmasterol, are ineffective. The antioxidant effect of Δ5-avenasterol increases with concentration in the range 0·01% to 0·1%.An hypothesis is presented to explain the effectiveness of the sterols as antioxidants. It is concluded that lipid free radicals react rapidly with sterols at unhindered allylic carbon atoms. Isomerisation leads to a relatively stable allylic tertiary free radical, which is slow to react further, and this interrupts the autoxidation chain.
Article
In this study, the chemical structure of the non-polar dimer triglycerides originating during heating is defined using an analytical method based on chromatographic techniques. The results of the application of this method to thermoxidised and thermally altered oils show that non-polar intramolecular dimers are not detectable while the presence of intermolecular dimers can be easily demonstrated.Die Bildung von apolaren dimeren Triglyceriden bei der thermischen Oxidation von SpeisefettenEs wird eine chromatographische Analysenmethode beschrieben, mit der die chemische Struktur der bei der Erhitzung gebildeten apolaren dimeren Triglyceride festgestellt werden kann. Die Anwendung dieser Methode bei thermoxidierten und thermisch umgewandelten Fetten zeigt, daß intramolekulare dimere Verbindungen nicht nachweisbar sind; die Anwesenheit von intermolekularen dimeren Verbindungen kann hingegen sehr leicht fest gestellt werden.
Article
The heat stability of oils and fats is believed to depend not only of their fatty acid pattern but also on the composition on the unsaponifiable fraction. The addition of the unsaponifiables isolated from wheat germ oil, corn oil, Vernonia anthelmintica or olive oil was found to retard oxidative polymerization in vegetable oils and model lipids subjected to heating (1-41. The protective effect of the non-glyceride fraction is ascribed to sterols and methylsterols containing the ethyliden group in the side chain [1, 2]. There is scant information on squalene as a potential oxidation inhibitor. According to Sims et al. a addition of 0.5 96 squalene markedly retarded the degradation of unsaturated fatty acids in safflower oil heated at 180°C [11]. As reported by Go-wind et al. squalene initially showing antioxidant properties for methyl oleate and methyl linoleate heated at 63°C was found to promote their oxidation at prolonged heating [IS].This paper contains the results of the experiments carried out to reveal the effect of squalene on the heat stability of rapeseed oil and two model lipids.
Article
The effect of extraction systems on the phenolic composition of virgin olive oils obtained from two different Italian cultivars (Coratina and Oliarola) was determined. The oils extracted using two-phase centrifugation showed in all cases higher phenolic concentration in comparison to oils obtained from three-phase centrifugation. In particular, the highest differences were observed for aglykone derivatives of oleuropein (3,4-DHPEA-EDA and 3,4-DHPEA-EA) that are the most concentrated antioxidant phenolic compounds of virgin olive oil. These results were confirmed by the autoxidation stability of the oils examined.Über die Auswirkung von Gewinnungsverfahren auf die Phenolzusammensetzung in unbehandeltem Olivenöl.Die Auswirkung von unterschiedlichen Extraktionssystemen auf die Phenolzusammensetzung in unbehandelten Olivenölen aus zwei verschiedenen italienischen Olivensorten (Coratina und Oliarola) wurde bestimmt. Öle, die mit dem Zweiphasen-Dekanter erzeugt wurden, zeigten in jedem Falle eine höhere Phenolkonzentration als Öle, die mit dem Dreiphasen-Dekanter gewonnen wurden. Insbesondere wurden höchste Unterschiede bei den Aglykonderivaten von Oleuropein (3,4-DHPEA-EDA und 3,4-DHPEA-EA) festgestellt, den am stärksten konzentrierten antioxidierenden Phenolverbindungen im unbehandelten Olivenöl. Diese Ergebnisse wurden durch die Stabilität der geprüften Öle gegen Autoxidation bestätigt.
Article
The effects of olive fruit extract on arachidonic acid lipoxygenase activities were investigated using rat platelets and rat polymorphonuclear leukocytes (PMNL). Olive extract strongly inhibited both 12-lipoxygenase (12-LO) and 5-lipoxygenase (5-LO) activities. One of the compounds responsible for this inhibition was purified and identified as 2-(3,4-dihydroxyphenyl)ethanol (DPE). DPE inhibited platelet 12-LO activity (IC50, 4.2 μμ) and PMNL 5-LO activity (IC50, 13 μμ) but not cyclooxygenase activity in cell-free conditions. It also inhibited 12-LO activity in intact platelets (IC50, 50 μμ) and reduced leukotriene B4 production in intact PMNL stimulated by A23187 (IC50, 26μμ). The inhibition by DPE of both lipoxygenase activities was stronger than that by oleuropein, caffeic acid, or 7 other related phenolic compounds, especially in intact cells. These results suggest that DPE is a potent specific inhibitor of lipoxygenase activities.