Article

Effect of the chemical refining process on composition and oxidative stability of evening primrose oil

Wiley
Journal of Food Processing and Preservation
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Abstract

The effect of therefining process on the physicochemical properties, fatty acid composition, bioactive components and antioxidant properties of evening primrose oil(EPO) wasinvestigated. The results showed that the peroxide value, acid value and p‐anisidine value changed significantly throughout the refining process (p< 0.05). Twelve fatty acids were identified in oil samples, while theirpercentage contents were not significantly different during the refining process. Contents of tocopherol and total phenols were removedby 23.5% and 79.4%, respectively, after refining. The refining process resulted in losses of campesterolandβ‐sitosterol of approximately 16.0%and 13.8%, respectively. Moreover, squalene was detected in evening primrose oil for the first time, and its content decreased by 20.2% during the refining process. Furthermore, during the whole refining process, the DPPH free radical scavenging ability of EPO decreased by 10.6%, and the FRAP reducing capacity dropped by 56%,meanwhile, its antioxidant stability was affected.

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... The generation of FFAs and a rise in the AV were caused by the adsorption of sodium ions in soap during the decolorization process. The fully refined oil AV was only 0.37 mg KOH/g, which was lower than expected, which indicates an improvement in the oil quality (Pan et al., 2020). ...
... The results show that the primary fatty acid composition of BCS oil, including linoleic, oleic, and palmitic acids, remained unchanged throughout the refining procedure (Table 2). These results agree with the findings of the refining effects on the sunflower, hazelnut, and evening primrose oil fatty acid compositions (Durmaz & Gökmen, 2019;Pal et al., 2015;Pan et al., 2020). ...
... In contrast, an increase in DPPH free radical inhibition capability was observed following the deodorization step. Most of the investigations showed a reduction in edible oils' antioxidant activity during refining due to the loss of bioactive compounds(Durmaz & Gökmen, 2019;Pan et al., 2020). However, some studies have found that antioxidant activity increases during some stages of refining. ...
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In this study, oil was extracted from black cumin ( Nigella sativa ) seed (BCS) by press, and oil was extracted from the obtained cake with a solvent. The changes in the quality of both crude oils obtained by pressing and by solvent were investigated during refining. Findings revealed that the p ‐anisidin value ( p ‐AV) and fatty acid profile did not change significantly, but there were significant differences ( p < .05) in the peroxide value (PV), reflective index, pigment contents, free fatty acid content (FFA%), and antioxidant activity (total phenol content (TPC), thymoquinone, and DPPH inhibition) of BCS oils obtained by the two different methods. PV and FFA decreased to less than 15 meqO 2 /kg and 0.3%, respectively, in the refined oil. The TPC (65%), thymoquinone (45–97%), carotenoids (86–89%), and chlorophyll (75–85%) were removed from BCS oil, but the DPPH value was raised by about 33%. The current study gives a clear picture of the changes during refining in BCS oil, which can be a useful guide in food applications.
... EPO is typically cold-percolated with n-hexane and vacuo-evaporated under low temperature to remove the organic solvent. 45 Nevertheless, more polar (and less toxic) organic solvents such as acetone or alcohol have been reported to be utilized though they are found to aect the extraction eciency of certain medicinal components of value in the oil. For example, 100% alcohol-extracted EPO showed the lowest yield and reduced levels of flavonoids and other phenolics, followed by acetone-extracted EPO. ...
... Hence, the determination of the physicochemical values of each stage is recommended such as acid value (AV), peroxide value (PV), iodine value (IV), para-anisidine value, and saponification value. 45 For instance, the acid value of EPO decreased significantly from 1.84 mg KOH per g in crude oil to 0.16 mg KOH per g as a result of oil treatment. In addition, PV can be dropped significantly after decolorization, from 6.89 to 1.01 mmol kg −1 . ...
... 109 Many in vitro screening assays such as ABTS-, DPPH-, peroxynitrite-, nitric oxide (NO)-, FRAP-, and hydroxyl radical-reducing/scavenging assays were reported to assess the EPO antioxidant power. 45,85,105,110 Among several seed extracts including chia, golden flax, fenugreek, and phacelia, saower, quince, rose, black seed, sea buckthorn, and borage, EP showed the highest total phenolics (TPC) to account for its superior antioxidant activity 26,111 and has yet to be confirmed for a comparison of its oil and these seeds oil for the results to be conclusive. TPC and total flavonoid content (TFC) were found to be enriched in defatted seeds. ...
Article
Oil crops have become increasingly farmed worldwide because of their numerous functions in foods and health. Particularly. Oil derived from the seeds of evening primrose (Oenothera biennis) (EPO) comprises essential fatty acids of the omega-6 (ω-6) series. It is well recognized to promote immune cells with a healthy balance and management of female ailments. The nutrients of exceptional attention in that oil are linoleic acid (LA, 70–74%) and γ-linolenic acid (GLA, 8–10%), which are polyunsaturated fatty acids (PUFA) to account for EPO popularity as a dietary supplement. Various other chemicals in EPO function together to supply the body with PUFA, elevate normal ω-6 essential fatty acid levels, and support general health and well-being. The inclusive EPO's biochemical analysis further succeeded in identifying several other components, i.e., triterpenes, phenolic acids, tocopherols, and phytosterols of potential health benefits. This comprehensive review capitalizes on EPO, the superior product of O. biennis highlighting the interrelationship between various methods of cultivation, extraction, holistic chemical composition, sensory characters, and medicinal value. Asides from literature review, this study restates the numerous health advantages of primrose oil and possible drug-EPO interactions since a wide spectrum of drugs are administered concomitantly with EPO. Modern techniques to evaluate EPO chemical composition are addressed with emphasis on the missing gaps and future perspectives to ensure best oil quality and nutraceutical benefits.
... Unpleasant compounds such as free fatty acids, phospholipids, and oxidation compounds have a negative effect on the physicochemical properties, sensory properties, and shelf life of edible oils (Chang et al., 2016;Mahjoob et al., 2017;Pestana et al., 2008;Zhu et al., 2016). During the process of chemical or physical refining, these compounds are removed and increase the quality of edible oils (Liu et al., 2019;Pan, Li, et al., 2020). In general, chemical refining includes degumming, neutralizing, bleaching, and deodorizing. ...
... In another study, Pan, Li, et al. (2020) reported that the chemical refining process of perilla seed oil eliminated tocopherols by 5%. The refining process has not always been accompanied by a slight reduction in useful compounds. ...
... Pal et al. (2015) also reported that the refining process had no significant effect on the fatty acid composition of sunflower oil. Similar results were reported in another study on evening primrose oil (Pan, Li, et al., 2020) that was consistent with the results of the present study. ...
Article
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The present study was conducted to investigate the impact of refining process on the chemical properties (fatty acid composition and tocopherols, sterols, and polyphenolic contents), qualitative parameters (peroxide value, acid value, and p‐anisidine value), and antioxidant activity (DPPH radical scavenging assay and FRAP test) of Baneh (Pistacia atlantica var mutica) kernel oil. The results revealed that the refining process had no significant effect on the fatty acid composition. A major finding of this research was the increase in the tocopherol and sterol content up to the bleaching stage followed by their decrease in the deodorizing phase. Some tocopherol and sterol compounds in crude oil were dimerized or attached to other compounds by ester bonding, which are released during some stages of the refining process and this factor is responsible for their increase. In fact, during this process, these compounds are regenerated. The occurrence of this phenomenon in the refining process improved the DPPH radical scavenging power of Baneh kernel oil up to the bleaching stage. Moreover, the content of phenolic compounds decreased after refining of Baneh kernel oil, and only in the deodorizing stage, an increase of these compounds was observed. In general, the results of this study showed that the refining process had a completely different effect on the antioxidant compounds (especially tocopherols) compared to other oils. In this research, for the first time in the world, Baneh (Pistacia atlantica) kernel oil was refined. Various researches have been done about this oil in its crude form, and it shows the high antioxidant activity and oxidative stability of this oil. Consumption of this oil is expanding, and this research provides useful information.
... Our study explored the potential benefits of using an alternative preservative for oil-based products, investigating the evening primrose oil, known for its active compounds such as tocopherols and phenols with antioxidant properties [28], in combination with sunflower oil. The oxidative stability of SFO combined with OBO was evaluated compared to those of pure SFO and SFO with BHT. ...
... A similar trend was also reported by others using essential oils or chili oils as supplementation for SFO, indicating decreased TOTOX values for different concentrations [22,33]. Evening primrose crude oil was previously reported as a tocopherol and phenolic compound-rich oil with good antioxidative properties [28]. The supplementation of SFO with evening primrose was investigated in another study that employed ethyl acetate extract, which expressed a better antioxidative activity than BHT (0.01%), extending the oil's shelf-life [36]. ...
Article
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There is a growing need for safer alternatives to synthetic additives commonly used in lipophilic carriers for products such as foods, pharmaceuticals, personal care items, and cosmetics. Natural antioxidants, which prevent lipid peroxidation while providing additional health benefits, offer a promising solution. Evening primrose oil, a rich source of antioxidant compounds with numerous biological benefits, emerges as a potential natural preservative for oil-based products. Our study evaluates a combination of sunflower oil, a widely used cold-pressed oil, with evening primrose oil for potential applications in various fields such as cosmetic, pharmaceutical, or food manufacturing. Various methods were applied to assess oxidative stability by calculating the peroxide value, the p-anisidine value, and the total oxidation value, while biological safety was evaluated using the chick embryo’s chorioallantoic membrane and histological analysis. The findings highlight that evening primrose oil, with its balanced effects on epithelial tissues and vascularization, as well as its strong anti-lipid peroxidation properties, is a suitable alternative to synthetic preservatives when used in combination with cold-pressed oils. This proposed oil combination, emphasizing the safety and beneficial properties of evening primrose oil, shows significant potential for applications in the pharmaceutical industry, dermatology, cosmetology, and food manufacturing.
... Water degumming has little effect on sterol content, while the major reduction occurs during neutralization, due to oil alkalization and high temperatures. Additionally, free sterols are partially distilled out during deodorization, with the extent of reduction depending on the deodorization temperature (Pan et al., 2020;Verleyen et al., 2002). In this study, the refining process resulted in a 19.78 % reduction in total sterol content, without altering the sterol profile. ...
... In this study, refining led to a 47.6 % reduction in total tocols content. Similar findings have been reported in other oils, with tocols content decreasing by 23.5 % in primrose oil (Pan et al., 2020), 8.86 % in hazelnut oil (Durmaz and Gökmen, 2019), 15 − 51 % in rapeseed oil, 0 − 82 % in soybean oil, 32 − 38 % in sunflower oil and up to 59 % in GSO (Yang et al., 2021;Régis et al., 2016). Wada et al. (2018) also reported a decrease in tocols of 27.7-54.1 % after refining muscadine GSO obtained with different extraction methods (Soxhlet with hexane, mechanical expression, and enzyme-assisted aqueous extraction). ...
... The results were expressed as a percentage of the relative peak area. The method was based on our previous study with slight modifications (Pan et al., 2020). ...
... γ-linolenic, which is believed to have benefits for human health, is one of the most prominent fatty acids in evening primrose oil. The content of γ-linolenic was 12.15 in the original EPO sample, which is consistent with our previous study (Pan et al., 2020). As the time increased, the content decreased to 11.99, 11.91, 12.01, 11.93 and 11.86, respectively. ...
Article
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Off-flavor is one of the limiting factors in the quality and commercial acceptability of evening primrose oil (EPO). The results of this study demonstrated that ultraviolet light irradiated with titanium dioxide (UV/TiO2) was able to effectively reduce odorous aldehyde concentrations, which would produce undesired flavors. Specifically, reductions in the E-2-Decenal, 1-octen-3-ol and hexanoic acid in EPO reached 50, 75.2 and 61.4% after a UV/TiO2 process of 5 min, respectively. The odor active values (OAV) and hierarchical cluster analysis (HCA) showed that the result of the 5 min group was similar to that of the original oil. In addition, the physicochemical characteristics of EPO after processing did not change significantly. The result of the aroma profile analysis was consistent with the OAV and HCA results. Therefore, it has been concluded that 5 min UV/TiO2 treatment could degrade some volatile compounds and provide a potential deodorization method for industry.
... 18 In a study investigating the beneficial clinical effects of cold-pressed primrose oil in comparison to the refined one, it was revealed that cold pressed oil has higher free radical scavenging properties because of its higher amounts of triterpenes. 19 In a study, palm oil carotenes and their tocotrienol-rich fractions were shown to have down regulating effects on pro-inflammatory markers such as Interleukin (IL)-6, IL-β, tumor necrosis factor (TNF), plasma CRP (c reactive protein) and plasma immunoglobulin E (Ig E), while increasing the IL-4 and 3. 20 The protective effect of red palm oil and its potential mechanisms of the neuroprotective actions were demonstrated in a comprehensive review paper. 21 Oxidative stress and inflammatory studies showed that generally, virgin or crude oils containing high amounts of bioactive micronutrients such as antioxidant compounds have higher antioxidant and antiinflammatory activities. ...
... Although refining the primrose oil decreases its micronutrients content, it doesn't significantly affect its fatty acid amounts. 19 Based on the studies, it can be inferred that there is still need for further investigation on the effect of refined and crude oils on MS progression. Figure 3 presents the effect and mechanism of virgin oil on neurodegenerative disorders. ...
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Neurodegenerative diseases are comprise a prominent class of neurological diseases. Generally, neurodegenerative diseases cannot be cured, and the available treatments can only regulate the symptoms or delay the disease progression. Among the several factors which could clarify the possible pathogenesis of neurodegenerative diseases, next to aging as the main risk, the dietary related diseases are the most important. Vegetable oils, which are composed of triacyclglycerols as the main components and several other components in a trace amount, are the main part of our diet. This review aims to study the effect of refined or unrefined vegetable oil consumption as a preventive or aiding strategy to slow or halt the progression of neurodegenerative diseases. In the refining process, owing to the chemical materials or severe temperatures of the refining process, removal of the desirable minor components is sometimes unavoidable and thus a worrisome issue affecting physical and neurological health.
... Starting from week-4, the p-anisidine value of BAO increased linearly suggesting a limited stabilization of hydroperoxides in BAO. It is noteworthy that the AnV decreased after the deodorization, likely due to the volatilization of secondary oxidation products and/or their degradation 43 . ...
Article
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Subquality argan kernels are 30% cheaper than the regular kernels mandatory used to prepare edible argan oil. The use of these argan kernels for the preparation of argan oil intended to be a cosmetic ingredient, after bleaching and deodorization, is therefore particularly economically appealing. The oxidative stability of Argan oil prepared from subquality kernels is unknown. It was evaluated over a period of storage of 12 weeks at 60 °C, then compared with that of argan oil stored under the same conditions and originating from the same initial batch, but which had subsequently been simply bleached and deodorized (physical refining). Physical refining led to an increase in initial oil quality due the loss of free fatty acids (up to 30% for refined argan oil), primary and secondary oxidation products but also to a dramatic decrease of the oxidative stability of argan oil caused by the loss of tocopherols, witnessed by the up to 94% loss after 12 weeks under accelerated storage conditions. As a conclusion, the oxidative stability of argan oil prepared from subquality argan kernels remains difficult to be adequately and efficiently evaluated since the initial quality of the argan kernels is the subject of great variations.
... A sequence of refining steps (stages) is commonly undertaken within the area of edible oil production. These stages generally contain degumming, neutralization, bleaching, and deodorization [37][38][39]. Throughout these refining processes, removing unwanted impurities due to a different manufacturing process or a change in vendor for cost reasons is an important objective. ...
Article
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Involving a succession of oil refining stages for edible oil production, a notable constraint lies in the necessity to employ diverse adsorbents at various steps within these processes. This study investigates the synthesis of mesoporous silica aerogels from rice husk ash, comparing their efficacy in physical sunflower oil refining with earth clay (Bentonite) and commercial silica (Trisyl). Tetraethyl orthosilicate (TEOS) impact during aging was analyzed using scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy (FTIR), and N2 adsorption-desorption analyzer to examine alterations in the structure of silica aerogels. The surface areas of TEOS-doped silica aerogel (TSA) and non-TEOS-doped silica aerogel (NTSA) were 296.18 and 267.06 m²/g. Mesoporous silica aerogels were evaluated for their ability to reduce free fatty acids (FFA), peroxide value (PV), phosphorus, and color pigments in sunflower oil. TSA and NTSA demonstrated significant FFA removal, with TSA at 3 wt.% achieving the highest performance of 32.2%. TSA also effectively reduced PV and phosphorus compared to NTSA, Bentonite and Trisyl, exhibiting performance similar to Bentonite in the bleaching process. TEOS-doped silica aerogels have shown promise as adsorbents for impurity removal in sunflower oil and has emerged as the potential adsorbent that can comprehensively and effectively meet the requirements of many edible oil physical refining applications in a singular step. Graphical Abstract
... The refined peanut oil was obtained by pressing and refining (Pan et al., 2020;Vaisali et al., 2015), the flow diagram of the experimental simulation of peanut oil refining process is shown in Fig. 1, including the oil extraction, degumming, deacidification and decolorization phases. Before pressing, the peanut raw materials were washed and dried at 37 • C. A household oil press was preheated and used to squeeze peanuts to obtain crude oil. ...
Article
Aflatoxin B1 (AFB1) contamination in peanut oil is a serious food safety concern. Classical edible oil refining process is an effective approach to remove AFB1. However, the transformation pathway, structure, and distribution of the transformation product of AFB1 in edible oil refining have not yet been reported in detail. In this work, we demonstrated that the degumming and deacidification were the critical phases for AFB1 removal from crude oil, in which 4.77% and 7.32% of AFB1 were transferred into the colloidal impurities and soap stock, and 87.91% of AFB1 was transformed to other compound. UPLC-Q-TOF MS and NMR analysis revealed that the AFB1 transformation product in peanut oil refining resulted from the hydrolysis of the lactone ring of AFB1. The lactone ring opened AFB1 (named OP-AFB1) in the soap stock can be converted into the original AFB1 under acidic conditions. Thus, the OP-AFB1 in soap stock was further detoxified via the Fenton treatment.
... The seed oil contents include high amounts of essential fatty acid such as γ-linolenic acid (GLA), a compound not commonly found in a normal diet (127). In addition, EPO contains tocopherols (such as α-, γ-, δ-tocopherol), phytosterols (such as β-sitosterol, campesterol) and phenolic compounds (46)(47)(48)(49). The oil is commonly used in the management of women's ailments including menopausal hot flashes (128), labor induction (129), cyclical mastalgia (130) and premenstrual syndrome (131). ...
... The fatty acid composition was determined according to the method proposed by Pan et al. (2020) with few modifications. Briefly, 100 mg (accurate to 0.1 mg) EPO were mixed with 2 mL of n-heptane and 2 mL of 2 M KOH-methanol, and shaken vigorously until well mixed. ...
Article
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The pollution of phthalic acid esters (PAEs) in edible oils is a serious problem. In the current study, we attempt to remove dibutyl phthalate ester (DBP) from evening primrose oil (EPO) with modified activated clay. The activated clay, commonly used for de-coloration in the oil refining process, was modified by chitosan and hexadecyl trimethyl ammonium bromide (CTAB). The modifications were characterized by SEM, XRD, and FT-IR. We further tested the DBP adsorption capacity of CTAB/chitosan-clay and found that the removal rate was 27.56% which was 3.24 times higher than with pristine activated clay. In addition, the CTAB/chitosan-clay composite treatment had no significant effect on the quality of evening primrose oil. In summary, the CTAB/chitosan-clay composite has a stronger DBP adsorption capacity and can be used as a new adsorbent for removing DBP during the de-coloration process of evening primrose oil.
... Gamma-linolenic acid is a well-known precursor to prostaglandin E (19) and is metabolized to arachidonic acid (20). The therapeutic effect of this plant is also attributed to the omega-6 essential fatty acid, which indirectly affects the synthesis of vaginal prostaglandins and cytokines (21). Consumption of EPO causes a significant increase in gammallenolic acid in the blood (22). ...
Article
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Background: Herbal medicine could be effective at treating various illnesses. Hysteroscopy can be an effective method for assessing the uterus in terms of anatomical, physiological and pathological anomalies. Objective: This study aims to evaluate the effect of evening primrose oil (EPO) on cervical preparation in women candidates for hysteroscopy. Materials and methods: This study was a double-blind, randomized controlled clinical trial including 160 women candidates for diagnostic hysteroscopy who were referred to Alzahra hospital from August 2019-March 2020. They were divided into 2 groups. Group A received 100 mg EPO as a soft gel capsule 6 hr before the hysterectomy in the posterior vaginal fornix. Group B received a placebo. After receiving the treatment, primary and secondary outcomes were evaluated in the groups. Results: The average Hegar size in the EPO group was larger than in the control group (p < 0.001 for both). Also, the need for mechanical dilation, the time taken until the first resistance and the time of dilatation completion in the EPO group were significantly less than in the placebo group (p < 0.008 for all). There was also greater ease of dilatation in the EPO group. Side effects such as uterine rupture, false passage, cervical rupture, allergic reaction, abdominal pain, nausea, diarrhea, headache and increase of bowel movements were not reported in any cases. Conclusion: Based on the findings of the present study, EPO is effective for cervical preparation in women undergoing hysteroscopy.
... Cold-pressing preserves a large amount of antioxidants (e.g., tocopherols, polyphenolic compounds) and also polyunsaturated fatty acids of the n-3 and n-6 group as well as sterols, indicating a potential of cold-pressed oils in antioxidant and bioactive effects [2][3][4][5]. In contrast to cold-pressing, the refining process causes a partial removal of nutritionally valuable compounds such as tocopherols, carotenoids, sterols, and polyphenolic compounds [6][7][8][9][10][11]. Therefore, there is a noticeable interest in cold-pressed oils among consumers looking for food with healthful properties. ...
Article
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The aim of the study was to examine combinations of base oils and herbal additives with a view to obtaining macerates with improved health benefits. Base oils were cold-pressed from the seeds of black cumin, borage, evening primrose, safflower, walnut, common hazel, and oilseed rape, as well as the flesh of sea-buckthorn fruits. They were then supplemented with herbs, including basil, thyme, and sage, in order to create macerates. Total antioxidant activity and tocopherol level were analyzed in oils, macerates, and oil cakes. Additionally, chemical properties of oil cakes—such as the level of fibre, vitamin C, β-carotene, and lutein—were also examined. Supplementation with herbs caused diversified effects on antioxidant activity and tocopherol level in macerates depending on the base oil, herb, and supplementation method. The obtained results indicate that tocopherol level does not play a decisive role in determining the antioxidant properties of oils, macerates, and oil cakes, suggesting significant involvement of other antioxidants. Among the tested macerates, the most promising one seems to be oilseed rape oil enriched with sage or basil to maximize its health benefits. The study can serve as a starting point for the development and implementation of functional macerates and oil cakes in healthy nutrition.
... Oenothera biennis (OB), commonly known as evening primrose, is an herbaceous plant of the family Onagraceae [9]. In recent decades, oil extracted from the seeds of OB (SOB) has drawn attention because of its high polyunsaturated fatty acid content (γ-linolenic acid) and excellent bioactive properties [10]. Thus, OB is globally cultivated as an industrial oil crop for the production of evening primrose oil (EPO) used in the development of pharmaceuticals, cosmetics, food products, bakery products, and confectionery [11]. ...
Article
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The defatted seeds of Oenothera biennis (DSOB) are a by-product of evening primrose oil production that are currently not effectively used. In this study, α-glucosidase inhibition, aldose reductase inhibition, antioxidant capacity, polyphenol composition, and nutritional value (carbohydrates, proteins, minerals, fat, organic acid, and tocopherols) of DSOB were evaluated using the seeds of Oenothera biennis (SOB) as a reference. DSOB was an excellent inhibitor of α-glucosidase (IC50 = 3.31 μg/mL) and aldose reductase (IC50 = 2.56 μg/mL). DSOB also showed considerable antioxidant capacities (scavenging of 2,2-diphenyl-1-picrylhydrazyl, 2,2’-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid, nitric oxide, peroxynitrite, and hydroxyl radicals). DSOB was a reservoir of polyphenols, and 25 compounds in DSOB were temporarily identified by liquid chromatography coupled with electrospray ionization–quadrupole time of flight–mass spectrometry analysis. Moreover, the carbohydrate, protein, and mineral content of DSOB were increased compared to that of SOB. DSOB contained large amounts of fiber and low levels of sugars, and was rich in calcium and iron. These results imply that DSOB may be a potential functional food ingredient for diabetes, providing excellent economic and environmental benefits.
... Similar results were reported in previous studies. The study on the refining process of sunflower oil revealed that the tocol contents would reduce during refining processes [46], and the contents of tocopherol in evening primrose oil were lowered by 23.5% during the chemical refining process [47]. Besides this, one report has proposed that the total tocopherol contents gradually decrease during all the refining processes in all oil types, and these significant losses occur especially during the deodorizing stage [48]. ...
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The consumption of vegetable oil is an important way for the body to obtain tocols. However, the impact of oil types and grades on the tocopherol and tocotrienol contents in vegetable oils is unclear. In this study, nine types of traditional edible oils and ten types of self-produced new types of vegetable oil were used to analyze eight kinds of tocols. The results showed that the oil types exerted a great impact on the tocol content of traditional edible oils. Soybean oils, corn oils, and rapeseed oils all could be well distinguished from sunflower oils. Both sunflower oils and cotton seed oils showed major differences from camellia oils as well as sesame oils. Among them, rice bran oils contained the most abundant types of tocols. New types of oil, especially sacha inchi oil, have provided a new approach to obtaining oils with a high tocol content. Oil refinement leads to the loss of tocols in vegetable oil, and the degree of oil refinement determines the oil grade. However, the oil grade could not imply the final tocol content in oil from market. This study could be beneficial for the oil industry and dietary nutrition.
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Black cumin seed oil, known for its bioactive compounds and health benefits, faces challenges due to its high peroxide value and free fatty acid content, limiting its applications. The study investigates oil extraction from black cumin seeds using cold pressing and solvent extraction. The oil extraction yields were found to be 32% from the seeds and 13% from the cake. Subsequently, the study investigated the impact of different refining steps on the quality of these oils. The oil extracted from the cake exhibited higher free fatty acid, chlorophyll, and carotenoid contents compared to the oil extracted from the seeds, with increases of 84%, 73%, and 66%, respectively. Conversely, the peroxide value, total phenol, and thymoquinone content of the cake‐derived oil were lower than those of the seed‐derived oil, with reductions of 74%, 69%, and 95%, respectively. The refining process resulted in general reductions in peroxide value, free fatty acid, and p‐anisidine levels. However, no significant effect on the fatty acid composition was observed. The refining led to a decrease in the bioactive content, including total phenolic compounds (6%–68%), carotenoids (86%–85%), and thymoquinone (50%–90%). These results contribute to a better understanding of the potential applications and refining requirements for black cumin seed oil.
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Phytosterols have health benefits; however, they are partially removed during the bleaching of corn oil. We evaluated the chemical conversion of free phytosterols (FPs) during bleaching. FP degradation accelerated with increased time and temperature, following a first-order kinetic model. In the n-heptane system, air and activated clay promoted the chemical conversion of the FPs. Sterenes formation was analysed under different conditions using a zero-order kinetic model. The apparent activation energies revealed sterene formation decreasing in the following order: campesta-3,5-diene ≈ stigmasta-3,5,22-triene > stigmasta-3,5-diene. Isomers of the above were not detected, indicating that these sterenes were the only primary products of FPs. The desorption test indicated that the FP loss from corn oil was not only due to FPs being adsorbed the activated clay, but also FPs adsorbed at acidic activated sites being degraded. This study presents a vital scientific foundation for retaining FPs to develop healthier and more nutritious oils.
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Evening primrose oil has a high market value due to its rich unsaturated fatty acids, so it is likely to be adulterated under the drive of economic interests. In this study, evening primrose oil's fatty acid and physicochemical properties were systematically determined, and the characteristic fatty acids were screened out. The feasibilities of GC‐MS and FT‐IR in identifying oil adulteration were also evaluated. Evening primrose oil's major fatty acids were linoleic acid (C18:2), γ‐linolenic acid (C18:3n6), palmitic acid (C16:0), oleic acid (C18:1) and stearic acid (C18:0). In addition, palmitoleic acid (C16:1), hexadecadienoic acid (C16:2), nonadecanoic acid (C19:0), eicosatrienoic acid (C20:3), erucic acid (C22:1), tricosanoic acid (C23:0) and lignoceric acid (C24:0) were rarely detected in other related studies on evening primrose oil. This study used fatty acids as indicators, hierarchical cluster analysis and cosine similarity analysis to identify evening primrose oil mixed with > 5% peanut oil and > 10% sunflower oil. Besides, the principal component analysis also distinguished evening primrose oil blended with different proportions of peanut and sunflower oils. In summary, this study confirmed that fatty acids could be characteristic indexes to identify adulterated evening primrose oil by GC‐MS and FT‐IR combined with chemometrics. Practical applications: This study further clarified the major and characteristic fatty acids of evening primrose oil. On this basis, the adulteration of evening primrose oil (taking peanut oil and sunflower oil as an example) was identified. Therefore, it is helpful to assess the quality and identify the authenticity of evening primrose oil, which is vital for the stability of the evening primrose oil market and the interests of consumers. These methods combined with chemometrics can also be extended to ensure certification of other oils and to classify oils into different classes. The improvements in vegetable oil quality will also benefit the vegetable oil industry and control bodies. This article is protected by copyright. All rights reserved
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Background: Despite advancements in cancer treatment, breast cancer (BC) is still one of the leading causes of death among women. The majority of anti-breast-cancer medications induce serious side effects and multidrug resistance. Although several natural compounds, such as evening primrose oil (EPO), have been shown to have anticancer properties when used alone, their combination with the anticancer medicine tamoxifen (TAM) has yet to be investigated. The present study aimed to investigate the anticancer efficacy of EPO, alone or in combination with TAM, in the BC cell lines MCF-7 and MDA-MB-231, as well as to elucidate the mechanism of action. Methods: The MTT assay was used to investigate the cytotoxic effect of EPO on the two cell lines, and we discovered an acceptable IC50 that was comparable to TAM. The ELISA, qRT-PCR, flow cytometry and colorimetric techniques were used. Results: The combination of EPO and TAM suppressed the VEGF level, VEGF gene expression and Cyclin D1 signaling pathways, arrested the cell cycle, and induced the apoptotic signaling pathways by increasing the Bax/Bcl-2 ratio and caspase 3 activity; this revealed significant anti-tumor activity. Conclusions: The most significant finding of this study was the confirmation of the anticancer activity of the natural product EPO, which potentiated the activity of the anticancer drug TAM against MCF-7 and MDA-MB-231 BC cell lines through the induction of apoptosis, inhibiting angiogenesis and halting cell proliferation.
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Evening primrose oil (EPO) is rich in linolenic acid, which has important physiological activity and attracted more and more attention. As a cold sterilization technology, irradiation is widely used in food preservation. However, the effect of irradiation on the flavour quality of EPO is unclear. The volatile aroma compounds examined by gas chromatography‐mass spectrometry (GC‐MS), combined with the odour activity value, are used to identify important odours in EPO. Principal component analysis (PCA), cluster heatmap analysis, and orthogonal partial least squares discriminant analysis are used to analyse the data to illustrate the impact of different radiation doses. The results show that the types and composition of volatile substances have changed, among which aldehydes have increased the most. Hexanal, (E,Z)‐2,4‐decadienal, and (E)‐2‐octenal, 1‐octen‐3‐ol were confirmed to play an important role in the formation of the green, fast, oily, and fishy aroma profile of EPO. In addition, the cluster analysis and PCA analysis showed that the flavour of 5 and 10 kGy was similar, but it was different from that of 1 kGy. In general, after the irradiation treatment, the flavour quality of EPO deteriorates, and the content of undesirable flavour substances increases. Additionally, the potential formation pathways and mechanism of volatile compounds were discussed. The research will help us to understand the change of the violate compounds under the γ‐irradiate process. The aroma characteristics of evening primrose oil with Co60 irradiation were analysed by HS‐SPME‐GC‐MS combined with multivariate analysis. The differences in the volatile components of the different dose treatment were studied.
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Herein, the physical migration and chemical conversion of phytosterols during the alkali neutralisation process of corn oil were investigated with molecular insights. A significant decrease in the phytosterol content was attributed to the migration from oil to the soapstock, along with slight chemical conversions between free phytosterols and phytosteryl esters in the heterogeneous system. Moreover, the migration of phytosterols was positively correlated with the water content in a model system through low-field nuclear magnetic resonance spectroscopy, which was attributed to the hydrogen bonding between free phytosterols and water. Compared to sodium oleate and sodium linoleate, sodium palmitate caused a higher loss of phytosterols due to its low solubility. X-ray diffraction analysis confirmed the formation of a bilayer structure of the sodium salt of fatty acids, suggesting the aggregation of the sodium salt of fatty acids and phytosterols at neutralisation temperatures. Small-angle X-ray scattering analysis suggested that the concentration of the NaOH solution affected the structure of sodium oleate and the area of the polar head base, which was associated with the loss of free phytosterols. The study presents an important fundamental scientific basis for the retention of phytosterols toward the development of more healthy and nutritious edible oils.
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The effect of the industrial chemical refining process on the physicochemical properties, fatty acid composition, and bioactive minor components of peanut oil was studied. The results showed that the moisture and volatile matter content, acid value, peroxide value, and p-anisidine value were significantly changed (P < 0.05) after the complete refining process. No significant variation (P > 0.05) in the iodine value was observed among all the peanut oil samples. Similar changes were observed in the DPPH radical scavenging activity and the total tocol content during chemical refining. In addition, chemical refining did not have much effect on the fatty acid composition, except for certain changes of several individual fatty acids. Moreover, the chemical refining resulted in 23.6, 23.1, and 9.5 % losses of squalene, total phytosterols, and total tocols (α, β, γ, δ-tocopherols and α, β, γ, δ-tocotrienols), respectively. The degumming–neutralization step caused the greatest overall reduction of these bioactive minor components. However, the concentrations of α-tocotrienol and γ-tocotrienol increased after full refining. Furthermore, chemical refining slightly changed the relative proportions of individual phytosterols and individual tocols.
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Evening primrose (Oenothera biennis L., Onagraceae) seeds oil has great economic importance due to its wide industrial application, mainly for medicines and nutraceutics. However, to our knowledge, it remains almost unexplored regarding development of innovative formulations, such as nanoemulsions. On the present study, required Hydroprophile–Lipophile Balance of evening primrose seeds oil was determined (HLB 12) and a stable nanoemulsion (Day 1: mean droplet size: 214.3±0.69nm, polydispersity index: 0.253±0.012. Day 7: mean droplet size: 202.8±0.23nm, polydispersity index: 0.231±0.008) was achieved. Moreover, pseudo-ternary diagram allowed delimitation of nanoemulsion region, contributing to nanobiotechnology of natural products.
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The effect of commercial refining steps on the peroxide value (PV), acid value (AV), carbonyl value (CV), total polar compounds (TPC) content, polar compounds distribution, and oil/oxidative stability index (OSI) of soybean and canola oils was studied. The PVs were changed during the different refining steps. The AVs significantly decreased after the neutralisation step. The CVs continuously increased during the refining steps. The marked decrease observed in the TPC contents after the neutralisation step was mainly due to the decrease in the content of free fatty acids (FFA) and oxidised triglyceride monomers (oxTGM) than in the content of the other polar compounds. On the contrary, the study showed more significant changes in diglycerides (DG) and triglyceride dimers (TGD) contents than in the FFA and oxTGM contents during the deodorisation step. The OSIs significantly decreased after the neutralisation step and indicated no considerable changes during the further refining steps.
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Hazelnut (Corylus avellana L.) oil was chemically refined using industrial refining conditions. Crude hazelnut oil was obtained by pre-pressing-solvent extraction methods and refined by neutralization, bleaching and deodorization in industrial scale. The changes in color, free fatty acids, fatty acid composition, tocopherol and phytosterol contents were determined after each step of refining. The main color change was observed during bleaching. Fatty acid composition, mainly oleic acid (81%), did not change significantly during the process. At the end of the refining, the amounts of total tocopherol and phytosterol decreased from 51.89 to 46.67 mg/100 g and from 168.04 to 141.48 mg/100 g, respectively. The biggest losses of both tocopherols and sterols were observed after neutralization. Deodorization caused a slight decrease in the amount of sterols. α-Tocopherol (36.19 mg/100 g), β-tocopherol (9.3 mg/100 g), and γ-sitosterol (120.28 mg/100 g) were the predominant unsaponifiables in refined hazelnut oil.
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The quality changes and the concentrations of tocopherols and γ-oryzanol, during successive steps of rice bran oil refining (RBO), were studied. For this purpose, samples of crude, degummed, neutralized, bleached, dewaxed and deodorized RBO were taken from an industrial plant and analyzed. The moisture, pH, acidity, peroxide value and unsaponifiable matter, were determined. The fatty acid composition was evaluated by GC, and the concentrations of tocopherols and γ-oryzanol were determined using HPLC with fluorescence and UV–Vis detection, respectively. To identify γ-oryzanol components, fractions of the HPLC eluant were collected and analyzed using mass spectrometry. Oil refining reduced the peroxide value and acidity to 1 and 3% of the values obtained in crude RBO, respectively. The fatty acid composition were not significantly altered during refining. The concentrations of the tocopherols in RBO followed the order α>(β+γ)>δ. The total concentration of tocopherols was 26mg/100g, and remained practically unaltered during refining. Up to nine components were distinguished in γ-oryzanol. After collecting the elution fractions, up to six components were identified by electrospray mass spectrometry. Refining reduced the total concentration of γ-oryzanol to 2% of its initial value.
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The influence of the refining process on the distribution of free and esterified phytosterols in corn, palm, and soybean oil was studied. Water degumming did not affect the phytosterol content or its composition. A slight increase in the content of free sterols was observed during acid degumming and bleaching due to acid-catalyzed hydrolysis of steryl esters. A significant reduction in the content of total sterols during neutralization was observed, which was attributed to a reduction in the free sterol fraction. Free sterols probably form micelles with soaps and are transferred into the soapstock. The steryl ester content remained constant during all neutralization experiments, indicating that hydrolysis of steryl esters did not take place during neutralization. During deodorization, free sterols are distilled from the oil, resulting in a gradual reduction in the total sterol content as a function of the deodorization temperature (220–260°C). A considerable increase in the steryl ester fraction was found during physical refining, probably owing to a heat-promoted esterification reaction between free sterols and FA.
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A Fourier transform-near infrared (FT-NIR) method originally designed to determine the peroxide value (PV) of triacylglycerols at levels of 10–100 PV was improved upon to allow for the analysis of PV between 0 and 10 PV, a range of interest to the edible oil industry. The FT-NIR method uses convenient disposable glass vials for sample handling, and PV is determined by spectroscopically measuring the conversion of triphenylphosphine (TPP) to triphenylphosphine oxide (TPPO) when reacted with hydroperoxides. A partial-leastsquares calibration was developed for 8 mm o.d. vials by preparing randomized mixtures of TPP and TPPO in a zero-PV oil. The method was validated with samples prepared by gravimetric dilution of oxidized oil with a zero-PV oil. It was shown that the American Oil Chemists’ Society primary reference method was quite reproducible (±0.5 PV), but relatively insensitive to PV differences at lower (0–2) PV. The FT-NIR method on the other hand was shown to be more accurate overall in tracking PV, but slightly less reproducible (0.9 PV) due to working close to the limit of detection. The sensitivity and reproducibility of the FT-NIR method could be improved upon through the use of larger-diameter vials combined with a detector having a wider dynamic range. The proposed FT-NIR PV method is simple to calibrate and implement and can be automated to allow for routine quality control analysis of edible fats and oils.
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The changes of total and individual tocopherols were investigated during different sunflower oil processing stages by reverse-phase high-performance liquid chromatography. The results revealed that the levels of total and individual tocopherol content were decreased during the neutralization, bleaching, and deodorization processes. The overall loss of total tocopherols during these stages was found to be 37.9%, although the general reduction trend of delta (δ), gamma (γ), and alpha (α) tocopherols is very similar during neutralization (35.3%), bleaching (38.3%), and deodorization (37.8%). However, in contrast to the neutralizing and deodorizing stages, the bleaching process caused relatively less reduction for individual tocopherol contents. Deodorizer distillates were also analyzed and were found to be rich with tocopherols content (29,348.24μg/ml). The results of the study indicated that most parts of the tocopherols are wasted during processing. Therefore, the proper concentration of nutritionists, industrialists, and manufacturers is needed for the necessary improvements in processing technology to avoid the major loss of tocopherols and to increase the shelf life, as well as the nutritive value of processed oil. KeywordsSunflower oil–Tocopherols–Refining stages–Reverse-phase HPLC
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The aim of this study is to evaluate the effect of refining steps on the squalene content of some vegetable oils. A comparison has been made between the crude oils and consecutive steps of refining process (neutralization, bleaching, deodorization, winterization) in the amounts of squalene of the oil samples. Among the oils, virgin and refined olive oils contained higher amounts of squalene. A mean of 491.0 ± 15.55mg/100g squalene was found in virgin olive oil samples. While appreciable quantities of squalene has been reduced during refining, considerable level of squalene were still present in refined olive oils (290.0 ± 9.89mg/100g). The squalene content of crude seed oils varied from 13.8 ± 0.39mg/100g to 26.2 ± 0.08mg/100g as average. It has been determined that refining process reduced the level of squalene in examined oils. The highest reduction in squalene content of the oils was detected during deodorization. The effect of refining steps on the amount of squalene in vegetable oils was found to be significant (p < 0.05). Olive oil has been considered an important source of squalene, even after it has been refined, compared to seed oils. KeywordsVegetable oils–Refining–Squalene
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The purpose of this work was to study the influence of the industrial process steps on free fatty acids, peroxide value (PV), p-anisidine value (PAV), trans fatty acids, tocopherols and sterols (free, esterified and total) in high oleic safflower oil. Degumming, bleaching and deodorization steps removed 91.4% of free fatty acids, 96.31% of oxidation primary products (PV), and 54.57% of oxidation secondary products (PAV), from crude high oleic safflower oil. Degumming neither affected the content of sterified sterols nor its proportion with respect to the crude oil. A significant increment (p<0.05) in the content of free sterols was observed during degumming and bleaching due to the acid-catalyzed hydrolysis of steryl esters. A significant reduction (p<0.05) in the content of total sterols during bleaching was observed, which is attributed to a reduction in the sterified sterol fraction. During deodorization, free sterols were distilled from oil, with a gradual reduction in the total sterol content as a function of the deodorization temperature. α- and γ-tocopherols represented 93.3% of the total tocopherols in high oleic safflower crude oil. The refining process removed 28.5% of the tocopherols. Deodorization was the main step which increased the level of trans fatty acids as an effect of temperature and heating time.
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The official regulations for the control of the olive and olive pomace oils of the European Union (EU) and International Olive Oil Council (IOOC) include the determination of fatty acids in order to be applied to several purity criteria. The determination of fatty acids require the preparation of the fatty acid methyl esters (FAME) for the subsequent analysis by gas chromatography with good precision and reproducibility. Among the methods used in the laboratories of both the industries and the official institutions looking after the olive oil control, the ones selected were: 1) cold methylation with methanolic potash and 2) hot methylation with sodium methylate followed by acidification with sulphuric acid in methanol and heating. A statistical assessment of the precision characteristics were performed on the determination of fatty acids using both methods by a collaborative trial following the directions included in the AOAC regulation (AOAC 1995). In oils with low acidities, the results obtained for both methylation methods were equivalent. However, the olive-pomace oil sample (acidity 15.5%) showed significative differences between the fatty acid compositions obtained using both methylation methods. Finally, the methylation with the acidic+basic method did not yield an increase of the trans-isomers of the fatty acids.
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To examine experimental evidence that has examined association of phytosterols and the reduction of the risk of cardiovascular disease and cancer. Phytosterols exist as naturally occurring plant sterols that are present in the nonsaponifiable fraction of plant oils. Phytosterols are plant components that have a chemical structure similar to cholesterol except for the addition of an extra methyl or ethyl group; however, phytosterol absorption in humans is considerably less than that of cholesterol. In fact, phytosterols reduce cholesterol absorption, although the exact mechanism is not known, and thus reduce circulating levels of cholesterol. The efficacy of phytosterols as cholesterol-lowering agents have been shown when incorporated into fat spreads as well as other food matrices. In addition, phytosterols have been combined with other beneficial dietary components including fish and olive oils, psyllium and beta-glucan to enhance their effect on risk factors of cardiovascular disease. Phytosterols appear not only to play an important role in the regulation of cardiovascular disease but also to exhibit anticancer properties. A side effect associated with the consumption of phytosterols is that they reduce the blood levels of carotenoid. Nevertheless, it has been suggested that compensation for this impact on serum carotenoid levels can occur either by increasing the intake of carotenoid-rich foods or by taking supplements containing these carotenoids. Dietary phytosterols appear to play an important role in the regulation of serum cholesterol and to exhibit anticancer properties.
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In this study, the effect of refining process on the content of phytochemicals, antioxidant capacity and oxidative stability of hazelnut oil was investigated. The oil samples were taken at the consecutive steps of hazelnut refining process and analyzed for some compositional properties along with the antioxidant capacity and oxidative stability. The results have shown that, carotenoid content of the hazelnut oil was decreased during the refining process. The main carotenoids of hazelnut oil were found to be lutein and zeaxanthin and these compounds were lost completely during bleaching step of the refining. On the other hand, phenolic compounds and tocopherols were also partly removed from hazelnut oil to a degree. Loses in antioxidant compounds caused a clear decrease in antioxidant capacity measured in either the oils or polar extract of oils. Oxidative stability of the oil samples was measured by Rancimat method and it was found that neutralization caused an increase in oxidative stability compared to the crude oil. However, deodorization step caused a slight decrease in oxidative stability probably as a result of partial removal of tocopherols at this stage.
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Background With a continuous increase in population and economic development, the demand for high quality seed oils keeps increasing in China. In the last decades, many minor edible oils become increasing and popular. Scope and approach In this review, the chemical composition and nutritional properties of minor edible oils, including flaxseed oil, corn oil, rice bran oil, camellia oil, safflower oil, almond oil, grape seed oil, walnut oil, perilla seed oil, pumpkin seed oil, evening primrose oil, Eucommia ulmoides Oliver seed oil, penoy seed oil, sea buckthorn seed oil, Acer truncatum Bunge seed oil, Torreya grandis seed oil and tomato seed oil, were summarized. The characteristic chemical compositions of these 17 kinds of minor edible oils were analyzed from fatty acid composition, phytosterols, tocopherols, total phenolic content, squalene and β-carotene contents. Key findings and conclusions Different types of vegetable oils have their own specific advantages and biological activities, and appropriate vegetable oils can be selected to meet individual needs accordingly. For example, Acer truncatum Bunge seed oil contains 5.52% nervonic acid (C24:1) that can promote the repair and regeneration of nerve cells and tissues damaged, while corn oil and rice bran oil have higher contents of campesterol and total phytosterol and might be therefore better choices for patients with high cholesterol and cardiovascular diseases. This review could benefit comprehensive understanding nutritional values of minor vegetable oils and future researches on nutrition and product development.
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Over the last two decades, separation, identification and measurement of the total and individual content of phenolic compounds has been widely investigated. Recently, the presence of a wide range of phenolic compounds in oil-bearing plants has been shown to contribute to their therapeutic properties, including anti-cancer, anti-viral, anti-oxidant, hypoglycemic, hypo-lipidemic, and anti-inflammatory activities. Phenolics in oil-bearing plants are now recognized as important minor food components due to several organoleptic and health properties, and they are used as food or sources of food ingredients. Variations in the content of phenolics in oil-bearing plants have largely been attributed to several factors, including the cultivation, time of harvest and soil types. A number of authors have suggested that the presence phenolics in extracted proteins, carbohydrates and oils may contribute to objectionable off flavors The objective of this study was to review the distribution, identification and occurrence of free and bound phenolic compounds in oil-bearing plants.
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Separation of squalene, a type of terpenoid hydrocarbons with important biological properties, from camellia oil by silver ion complexation was studied. We showed that the UV-visible absorption wavelength of squalene in AgNO3-methanol solution was obviously red-shifted, and the infra-red vibration wavelength of C=C bond slightly decreased, indicating that complexation between squalene and Ag+ took place. The distributions of squalene in AgNO3 methanol solution /petroleum ether under different conditions were further investigated. We found that the fraction of squalene in AgNO3-methanol phase was enhanced with increased percentage of methanol and AgNO3 concentration and decreased extraction temperature. The distribution coefficient of squalene was up to 7.87 under optimum extraction conditions with 70% methanol (v/v), 0.6 mol/L AgNO3, reaction time of 12 h, and at the temperature of 0 °C. Furthermore, under the optimum conditions, extraction of squalene from the unsaponifiable portion of camellia oil exhibited high selectivity with a raffinate rate and a back-extraction rate of 73.9% and 72.5%, respectively. The purity of extracted squalene was 37.8%, 108 times more concentrated than that in the starting material.
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Crude kenaf seed oil was obtained by solvent extraction and chemically refined using industrial refining process, which includes degumming, neutralization, bleaching, and deodorization. The changes in physical characteristics, oxidation indexes, antioxidant activity, bioactive compounds, and fatty acid composition were determined after each stage of refining. The results obtained showed that there was no significant difference in the specific gravity of kenaf seed oil, but there was a significant increase in the refractive index and a significant decrease in the a* and b* values in the color determination after the refining. Peroxide value decreased from 2.64 to 0.55 meq/kg, p-Anisidine value increased from 2.41 to 3.41, TOTOX value decreased from 7.70 to 4.51, and free fatty acids decreased from 1.72 to 0.61 after the whole refining process. There was a removal of 64.5% of total phenolic content, 65.3% of total carotenoid content, 22.5% of phytosterol content and high retention of tocopherol content in kenaf seed oil after refining. Kenaf seed oil showed an increasing of 84.5% and 58.6% in DPPH value and ABTS+ value, respectively. Oleic acid was found in the largest amount in the refined kenaf seed oil (35.1%), followed by linoleic acid (32.3%) and palmitic acid (21.9%). There was a slight increase in unsaturated fatty acids and a slight decrease in saturated fatty acids after refining. This work showed that the chemical refining process offers an improvement in the quality of kenaf seed oil.
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The main purpose of this article was to investigate the influence of individual processes in physical refining on tocopherol content in sunflower and rapeseed oils. During refining some chemical parameters, the oxidative stability of oils and some minor compounds such as chlorophyll and beta‐carotene, were determined. Those analytical data with explained chemical backgrounds gave more qualitative overview of what happened to the same lot of oils being processed in a continuous operation. Some processes were compared with a laboratory oil refining. Crude rapeseed oil contained 656 mg/kg of total tocopherols, followed by high oleic sunflower with 373 mg/kg of tocopherols and classic sunflower oil with 332 mg/kg of tocopherols. The most serious refining processes were bleaching and physical deodorization process, the tocopherol losses being 14.9–17.4% and 20.2–27.1%, respectively. In the refined oils, chlorophylls and FFAs were almost completely removed and the oxidative stability increased 2–3 times. Vegetable oil refining process caused relatively great losses of minor compounds but this, in turn, prolonged the shelf life of edible oils. Practical applications: It was proved that refining of sunflower and rapeseed oils in the oil refinery improves their basic chemical parameters. The loss of tocopherols can be minimized by shortening the time and lowering the temperature during the final step of physical refining, but it has to remain within requirements on quality of refined edible oils. The refining processes of sunflower and rapeseed oils lead to 39.0–45.5 % loss of total tocopherol content. The most serious refining processes were bleaching and physical deodorization process, the tocopherol losses being 14.9–17.4 % and 20.2–27.1 %, respectively. Degumming process can caused 6.6–8.4 % decrease of tocopherols in sunflower and rapeseed oil. Most gentle process was winterization of sunflower oils which caused only 2.9–5.8 % tocopherols decrease.
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Evening Primrose oil (EPO) is a natural product extracted by cold-pressed from Oenothera biennis L. seeds. EPO is widely used as a dietary supplement from which beneficial effects have been reported in rheumatic and arthritic conditions, atopic dermatitis, psoriasis, premenstrual and menopausal syndrome, and diabetic neuropathy. The beneficial effects of EPO are thought to be due to its gamma-linolenic acid content; in contrast, little effort has been expended to characterize the non-triglyceridic constituents of EPO. In order to evaluate its potential as source of functional food ingredients our aim in this work has been identified and quantified the different components of EPO by different techniques (GC-MS and HPLC). The lipid profile showed that oleic (7%), linoleic (74%) and g-linolenic (9%) were the most abundance fatty acids. Unsaponifiable matter and subfractions were obtained by CEE/2568/91. Separation of the compounds under study was achieved giving a reasonable analysis time and good resolution. A yield (1.82-1.95%) of unsaponifiable matter was obtained and levels of saturated hydrocarbons (0.291.97 +/- 14.85 mg) were noticed. beta-Sitosterol (7952.00 +/- 342.25 mg/ kg oil) and campesterol (883.32 +/- 0.45 mg/ kg oil) were predominant in phytosterol fraction (9573 mg/ kg oil), while tetracosanol (236.93 +/- 2.32 mg/ kg oil) and hexacosanol (289.92 +/- 3.41 mg/ kg oil) in linear aliphatic alcohol fraction (798.04 +/- 5.66 mg/ kg oil). In the phenolic fraction (55.49 +/- 2.76 mg/ kg oil), ferulic acid (25.23 +/- 2.64 mg/ kg oil) was the major component. From the results obtained, it can be suggested that the Evening Primrose oil can be considered an interesting alimentary source of substances of nutraceutical value. (c) 2013 Phytochemical Society of Europe. Published by Elsevier B.V. All rights reserved.
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The total free radical scavenger capacity (RSC) of 57 edible oils from different sources was studied: olive (24 brands of oils), sunflower (6), safflower (2), rapeseed (3), soybean (3), linseed (2), corn (3), hazelnut (2), walnut (2), sesame (2), almond (2), mixture of oils for salad (2), "dietetic" oil (2), and peanut (2). Olive oils mere also studied according to their geographical origins (France, Greece, Italy, Morocco, Spain, and Turkey). RSC was determined spectrophotometrically by measuring the disappearance of the radical 2,2-diphenyl-1-picrylhydrazyl radical (DPPH.) at 515 MI. The disappearance of the radical followed a double-exponential equation in the presence of oils and oil fractions, which suggested the presence of two (fast and slow) groups of antioxidants. RSC was studied for the methanol-soluble phase ("methanolic fraction", MF) of the oil, the fraction nonsoluble in methanol ("lipidic fraction", LF), and the nonfractionated oil ("total oil"; TF = MF + LF). Only olive, linseed, rapeseed, safflower, sesame, and walnut oils showed significant RSC in the MF due to the presence of phenolic compounds. No significant differences were found in the RSC of olive oils from different geographical origins. Upon heating at 180 degrees C the apparent constant for the disappearance of RSC (k(T)) and the half-life (t(1/2)) of RSC for MF, LF, and TF were calculated. The second-order rate constants (k(2)) for the antiradical activity of some phenolic compounds present in oils are also reported.
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In this work, a pretreatment process for rapeseeds, which involves the use of high-temperature steam, is presented. This method, besides accomplishing the beneficial effects of the conventional industrial thermal treatment, leads to an enrichment of some important minor compounds (polyphenols and phosphatides) in the resulting oil. Rapeseeds were pretreated at different operative conditions. Then, the seeds were pressed and the press-cake was solvent extracted. The obtained oils were then refined by both chemical and physical refining techniques, and the influence of each refining step on the content of minor compounds was evaluated. The results show that the amounts of polyphenols and phospholipids present in the oil coming from pretreated seeds increase and that their concentrations depend on the conditioning time. The polyphenols present in the oil correspond mostly to 2,6-dimethoxy-4-vinylphenol (vinylsyringol). The content of polyphenols was only slightly reduced during degumming. Neutralization resulted in a complete removal of these minor compounds. For the physical refining process, the type and amount of bleaching clay used had a significant influence on the content of polyphenols. After deodorization, oil samples with a considerable amount of polyphenols were obtained. These samples show a higher oxidative stability than chemically refined oils.
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Total and individual tocopherol contents of sunflower oil, processed either by chemical refining (CR), physical refining (PR) or soft column deodorization (SCD) methods were investigated. Total tocopherol content gradually decreased until the end of the refining process (the deodorization stage). Among the refining methods used CR and PR caused higher losses in the tocopherol content when compared with the SCD method. The content of α-, β-, γ- and δ-tocopherols also decreased as a result of the refining process. These significant losses in β- and γ-tocopherol contents were determined after the deodorization stage.
Article
Many nontraditional vegetable oils have been introduced to the market relatively recently, and therefore data on their antioxidant potential have not been reported. Such data are of importance for the evaluation of the nutritional and health impact of these oils. Antioxidant properties of the methanolic extracts of cold-pressed oils such as soybean, sunflower, rapeseed, corn, grapeseed, hemp, flax, rice bran and pumpkin were studied. The methanolic extracts were obtained by solid phase extraction and separation, and identification of phenolic acids was conducted by high-performance liquid chromatography. The obtained extracts were characterized by different scavenging activities of 2,2-diphenyl-1-picrylhydrazyl radicals. The best antioxidant properties were displayed by the extract from hemp, pumpkin and rapeseed oils. The highest content of total phenolic compounds was determined for the pumpkin and hemp oils – about 2.4 mg/100 g. Rapeseed oil was characterized by the highest content of phenolic acids, especially sinapic acid. To better understand the beneficial effects of antioxidant compounds in vegetable oils, it is important to investigate whether these bioactive compounds in oils differ in their reactions with free radicals. Phenolic compounds have been reported to be present in all vegetable oils, which is very important for the oxidative stability of the polyunsaturated fatty acids of these oils. Additionally, edible oils rich in natural antioxidants may play a role in reducing the risk of chronic diseases. Thus, the oils examined may be used in different food applications to provide nutrition and health benefits.
Article
Among the most important metabolic compounds there are some which are not synthesized by human and animal organisms and have to be supplied in appropriate quantities in due time. Vitamin E and the essential unsaturated fatty acids have crucial physiological significance, and their greatest quantities occur in plant oils. During refining, apart from unnecessary substances, nutritionally advantageous compounds are also being eliminated. In the present paper changes of tocochromanols taking place during refining of rapeseed oil obtained from seeds of two subsequent crops were investigated. It was observed that losses of tocopherols exceeded 30%, two thirds of which resulted from distilling off during deodorization. The ratio of vitamin E to essential unsaturated fatty acids expressed as the Harris coefficient decreased in the refined oil obtained from seeds of two subsequent crops by about 28%.
Article
Plant sterols are an essential component of the membranes of all eukaryotic organisms. They are either synthesised de novo or taken up from the environment. Their function appears to be to control membrane fluidity and permeability, although some plant sterols have a specific function in signal transduction. The phytosterols are products of the isoprenoid pathway. The dedicated pathway to sterol synthesis in photosynthetic plants occurs at the squalene stage through the activity of squalene synthetase. Although the activity of 3-hydroxymethyl-3-glutaryl coenzyme A (HGMR) is rate-limiting in the synthesis of cholesterol, this does not appear to be the case with the plant sterols. Up-regulation of HGMR appears to increase the biosynthesis of cycloartenol but not the Δ5-sterols. A decline in sterol synthesis is associated with a suppression of squalene synthetase activity, which is probably a critical point in controlling carbon flow and end-product formation. The major post-squalene biosynthetic pathway is regulated by critical rate-limiting steps such as the methylation of cycloartenol into cycloeucalenol. Little is known about the factors controlling the biosynthesis of the end-point sterol esters or stanols. The commonly consumed plant sterols are sitosterol, stigmasterol and campesterol which are predominantly supplied by vegetable oils. The oils are a rich source of the steryl esters. Less important sources of sterols are cereals, nuts and vegetables. The nutritional interest derives from the fact that the sterols have a similar structure to cholesterol, and have the capacity to lower plasma cholesterol and LDL cholesterol. Since the morbidity and mortality from cardiovascular disease have been dramatically reduced using cholesterol-lowering drugs (statins), the interest in plant sterols lies in their potential to act as a natural preventive dietary product. Stanols (saturated at C-5) occur in low amounts in the diet and are equally effective in lowering plasma cholesterol and do not cause an increase in plasma levels, unlike the sterols which can be detected in plasma.© 2000 Society of Chemical Industry
Article
A method is described for simultaneously determining tocopherols and sterols in fats and oils by quantitative capillary gas chromatography. Samples containing ca. 100 mg of lipid were saponified in capped tubes with aqueous KOH by heating for 8 min at 80 C; the unsaponifiable fraction was extracted with cyclohexane, freed of solvent, derivatized to form the trimethylsilyl ethers of both tocopherols and sterols, and chromatographed on a 50 m×0.25 mm glass capillary column coated with Dexsil 400. Most of the individual tocopherols and common sterols were well separated, although interfering peaks were seen in some samples, which for better specificity should be subjected to an initial purification. For most samples, however, the simplified sample preparation, without preliminary purification, was adequate when combined with capillary gas chromatography. Recovery, method and gas liquid chromatographic precision, and applications are discussed.
Article
An industrially degummed Indonesian palm oil was bleached and steam refined in a pilot plant to study the effect of processing on oil color and on the levels of carotenoids and tocopherols. Five concentrations of one natural and two activated clays mixed with a fixed amount of synthetic silica were used for bleaching. For color measurement, the Lovibond method was compared to the CIE (Commission Internationale de l’Eclairage) L*,a*,b* method. The results showed that the L*,a*,b* method is repeatable and that the values found are highly correlated with the carotenoid content of bleached oil samples. The various clays and synthetic silica mixes removed 20–50% of the carotenoids in the degummed oil, depending on clay concentration and activity. For the two activated clays, pigment adsorption increased with clay amount. Steam refining totally destroyed carotenoids in the claytreated oils by heat bleaching. Total tocopherols in the crude oil amounted to 1000 mg/kg, with γ-tocotrienol as the main tocopherolic component followed by α-tocopherol, α-tocotrienol, and δ-tocotrienol. Tocopherol concentrations increased after the bleaching treatment with the most acid clay, and the increase was proportional to the amount of clay used. Both bleaching and steam refining changed the ratios between the various to copherolic components, especially increasing the relative concentration of α-tocotrienol in the refined oil. An average 80% tocopherol retention was obtained after the treatment with acid clay + synthetic silica and steam refining of palm oil.
Article
The oxygen radical absorbance capacity (ORAC) and the ferric reducing antioxidant power (FRAP) methods were used for the determination of antioxidant capacities (AC) of rapeseed oils at different steps of technological process and olive oils. The mean ORAC and FRAP results obtained for rapeseed oils (1,106–160 and 552–95.6μmol TE/100g) were higher than for olive oils (949–123 and 167–32.1μmol TE/100g). Although, FRAP values were lower than ORAC values for all studied oils, there is a linear and significant correlation between these two analytical methods (r=0.9665 and 0.9298, P<0.0005) for rapeseed and olive oils, respectively). Also, total phenolic compounds in rapeseed oils and olives correlated with antioxidant capacities (correlation coefficient ranged between 0.9470 and 0.8049). The refining process of rapeseed oils decreased the total phenolics content and antioxidant capacities by about 80%.
Article
Evening primrose (Oenothera spp.) seed contains ca. 15% protein, 24% oil, and 43% cellulose plus lignin. The protein is unusually rich in sulphur-containing amino acids and in tryptophan. The component fatty acids of the oil are 65–80% linoleic and 7–14% ofγ-linolenic, but noα-linolenic acid. The 1.5–2% unsaponifiable matter has a composition very similar to that of cottonseed oil. The sterol fraction contains 90%β-sitosterol and the 4-methyl sterol fraction contains 48% citrostadienol;γ-tocopherol dominates its class, with someα- but no other tocopherols.
Article
The effects of each individual step of the chemical refining process on major and minor components of rice bran oil were examined. In comparison with common vegetable oils, rice brain oil contains a significantly higher level of several bioactive minor components such as γ-oryzanol, tocotrienols, and phytosterols. Alkali treatment or neutralization results in a significant loss of oryzanol. In addition, it gives rise to a change in the individual phytosterol composition. After bleaching, some isomers of 24-methylenecycloartanol were detected. Because of their relatively high volatility, phytosterols and tocotrienols are stripped from the rice brain oil during deodorization and concentrated in the deodorizer distillate. At the same time, oryzanol is not volatile enough to be stripped during deodorization; hence, the oryzanol concentration does not change after deodorization. Complete refining removed 99.5% of the FFA content. Depending on the applied deodorization conditions, trans FA can be formed, but the total trans content generally remains below 1%.
Article
Addition of certain vegetable oil unsaponifiables to safflower oil protects it from oxidative polymerization during heating at frying temperature. The unsaponifiables isolated from olive, corn, wheat germ andVernonia anthelmintica oils were found to be effective. The fraction responsible for this effect is largely sterol in nature. Although the common plant sterols show no antioxidant activity, the 4-α-methyl sterols function well. The sterols fromVernonia oil, which contain no 4-α-methyl group, are also active. It appears that an isofucosterol side chain may be the structural feature required to obtain this protective effect.
Article
We report the effects of individual steps of industrial refining, carried out in Brazil, on the alteration of selected minor constituents of oils, such as corn, soybean, and rapeseed oils. Total sterols, determined by capillary gas chromatography (GC), decreased by 18–36% in the fully refined oils, compared with the crude oils. The total steradienes, dehydration products of sterols, were determinedvia a simple clean-up on a short silica gel column, followed by high-performance liquid chromatography (HPLC) with ultraviolet detection. The level of steradienes, normally not present in crude oils, increased after each refining step, especially after deodorization. Thus, the content of steradienes increased after deodorization by about 15- to 20-fold in corn and soybean oils, and by about 2-fold in rapeseed oil. The total steryl esters were also determinedvia clean-up on a short silica gel column, followed by HPLC with evaporative light scattering mass detection. A minor decrease in the level of steryl esters was observed after complete refining. The individual tocopherols and tocotrienols were determined by HPLC with a fluorescence detector. The level of total tocopherols and tocotrienols decreased by about 2-fold after complete refining of corn oil and by about 1.5-fold in soybean and rapeseed oils. In all three cases, maximum reduction of tocopherols was observed after the deodorization step. The level of polymeric glycerides, determinedvia clean-up on a short silica gel column followed by size-exclusion HPLC, increased to some extent (0.4–1%) during refining. The level oftrans fatty acids, determined by capillary GC, also increased to a substantial extent (1–4%) after refining.
Article
The antioxidant properties of potato peels and sugar beet pulp, in comparison with synthetic antioxidant, were investigated. The bioactive materials were extracted with methanol and examined for their antioxidant activity under accelerated oxidation conditions, using sunflower and soybean oils as oxidation substrates at different concentrations for 72 h at 70 °C. Inverse relationships were noted between peroxide values and oxidative stabilities and also between secondary oxidation products, measured by p-anisidine value and stabilities at termination of the storage. Absorptivity at 232 nm and 270 nm increased gradually with the increase in time, due to the formation of conjugated dienes and polyenes. The order of oxidative stability was as follow: TBHQ > potato peels > BHT = sugar beet pulp > BHA. The predominant phenolic compounds identified by thin-layer chromatography in potato peels and sugar beet pulp were chlorogenic and gallic acids. The results of different antioxidant parameters demonstrated that potato peels and sugar beet pulp are potent sources of natural antioxidants that might be explored to prevent oxidation of vegetable oils.
Article
Because of the high temperatures applied in classical refining processes, many quantitative and qualitative changes occur in the chemical compositions of oils. This causes refined olive oil to lose many of its organoleptic and nutritional properties. Research has been carried out to ascertain the influence of a soft purification process, based on oil conditioning, to form micronic aggregates which were subsequently removed by a microfiltration operation. The quasi total acidity and the resulting soaps were removed in a single microfiltration step. The deacidified and filtered oils showed similar peroxide values and the variation of the specific extinction around 270 nm (ΔK) was slightly improved. The process lowered the monoglyceride contents up to 78% while the diglyceride contents were just slightly decreased. The various sterol components were also lowered (in the range 36–50%) upon treatment. Phenolics were the most affected components; reductions reached 93%. The partitioning of such components between the bulk triglyceridic medium and the aggregate phase are considered with regard to their properties. Despite the low operating temperature, the sensory evaluation of the deacidified and filtered oils still showed poor organoleptic characteristics.
Article
Minor components in edible oils affect both their autooxidative and photooxidative stabilities. Thus, stripping of minor components may influence stability of oils being studied. The impact of natural endogenous pigments on photooxidative stability of stripped and non-stripped borage and evening primrose oils and their emulsions in water was studied. Peroxide values (PV) of non-stripped borage and evening primrose oils and their emulsions in water were significantly (P<0.05) higher than corresponding values for stripped oils and their emulsions in water. A similar trend was observed when considering hexanal contents of bulk oils and their corresponding oil-in-water emulsions. These results indicate that minor components, especially endogenous chlorophylls, play a major role in the photooxidation of borage and evening primrose oils and their emulsions in water.
Article
The tocopherol and tocotrienol (i.e. tocol) and plant sterol contents of 14 vegetable and 9 industrial fats and oils available on the Finnish market in 2005 were determined using NP-HPLC with fluorescence detection (tocols) and GC-FID (plant sterols). Best sources of α-tocopherol were wheat germ (192 mg/100 g) and sunflower oil (59 mg/100 g). Oils richest in γ-tocopherol were camelina (72 mg/100 g), linseed (52 mg/100 g) and organic rapeseed oil (51 mg/100 g). Total tocol contents were between 4.2 mg/100 g (coconut fat) and 268 mg/100 g (wheat germ oil). Plant sterol contents ranged from 69 mg/100 g in a frying fat to 4240 mg/100 g in wheat germ oil. Organic rapeseed oil, the second best source of plant sterols, contained 887 mg/100 g. The variations of the total tocol and sterol contents in 10 rapeseed oil sub-samples analysed separately were 9.7% for tocols and 9.9% for sterols in refined rapeseed oil, and 6.3% for tocols and 4.2% for sterols, respectively, in cold-pressed rapeseed oil. In addition to the target compounds, plastochromanol-8 could be determined in all plant-based samples with contents ranging from 0.13 (walnut oil) to 18 mg/100 g (linseed oil). The lignans sesamin and sesamolin could be identified in sesame oil.
Article
Fatty acid composition, total phenols, phenolic and volatile profile data are presented for cold-pressed and refined camellia oil, in comparison to other commercially available oils – avocado, pumpkin, sesame and soybean – representing a cross-section of bulk, “bland” oils (e.g., soybean) through to more boutique oils consumed primarily for taste (e.g., pumpkin). Camellia oil has a high oleic acid content, low polyunsaturated acid content, and levels of endogenous phenols comparable, in quantity and diversity, to cold-pressed oils. Volatile profiles of camellia oil are also comparable to cold-pressed oils, in that alkanals are the dominant headspace compounds, as measured by solid-phase microextraction gas chromatography. These factors suggest that camellia oil may find much wider commercial acceptance outside its current market range, southern China.
Article
Diets rich in arachidonic acid (20:4n-6) lead to the formation of 2-series prostaglandins (PGs) and 4-series leukotrienes (LTs), with proinflammatory effects. Nonsteroidal antiinflammatory drugs are used in rheumatoid arthritis to inhibit cyclooxygenase (prostaglandin-endoperoxide synthase), thereby decreasing production of 2-series PGs. Lipoxygenase activity remains intact, however, allowing LT production (eg, synthesis of LTB(4), a potent inflammatory mediator) to continue. Altering the essential fatty acid (EFA) content of the diet can modify some of these effects. Ingestion of a diet rich in evening primrose oil elevates concentrations of dihomo-gamma-linolenic acid (DGLA; 20:3n-6), which results in the production of 1-series PGs, eg, PGE(1). DGLA itself cannot be converted to LTs but can form a 15-hydroxyl derivative that blocks the transformation of arachidonic acid to LTs. Increasing DGLA intake may allow DGLA to act as a competitive inhibitor of 2-series PGs and 4-series LTs and thus suppress inflammation. The results of in vitro and animal work evaluating EFAs in inflammatory situations are encouraging, which has stimulated clinical workers to evaluate these compounds in rheumatoid arthritis. Several well-controlled, randomized clinical studies have now been completed in which various EFAs were evaluated as treatments. The results of most of these studies suggest some clinical benefit to these treatments; these data are reviewed here.
Article
Tocopherols in commercially grown normal, mid- and high-oleic Runner peanuts from 2005 and 2006 were quantified to give accurate vitamin E contents. Tocopherols were extracted from raw peanuts by a direct solvent extraction procedure using 10% ethyl acetate in hexanes that provided percent recoveries of 105.4, 101.2, 103.9, and 102.8 for alpha-tocopherol (T), beta-T, gamma-T, and delta-T, respectively. No significant (P > 0.05) differences were noted in total tocopherol levels in normal- (22.4 mg/100 g), mid- (23.9 mg/100 g), and high-oleic (22.4 mg/100 g) Runner peanuts. alpha-T levels did vary significantly among the Runner cultivars classified by their oleic acid content (mid, 11.7 mg/100 g; normal, 10.9 mg/100 g; high, 9.8 mg/100 g). Cultivar effects were highly significant (P < 0.001) for alpha-, beta-, gamma-, and delta-T and total tocopherol contents, whereas production year effects were highly significant for alpha- and beta-T levels. Year x cultivar interactions were not significant (P > 0.05). Cluster analysis segregated the cultivars into two major groups represented by lower alpha-T and higher gamma-T levels (cluster A) and high alpha-T and low gamma-T levels (cluster B) (P < 0.05). The mean alpha-T level in Runner peanuts (151 samples) was 10.5 +/- 1.5 mg/100 g, which is 26.7% greater than the imputed value for peanuts, all types (NBD 16087) provided by the USDA National Nutrient Database for Standard Reference.
Article
Polyphenols constitute one of the most numerous and ubiquitous groups of plant metabolites and are an integral part of both human and animal diets. Ranging from simple phenolic molecules to highly polymerized compounds with molecular weights of greater than 30,000 Da, the occurrence of this complex group of substances in plant foods is extremely variable. Polyphenols traditionally have been considered antinutrients by animal nutritionists, because of the adverse effect of tannins, one type of polyphenol, on protein digestibility. However, recent interest in food phenolics has increased greatly, owing to their antioxidant capacity (free radical scavenging and metal chelating activities) and their possible beneficial implications in human health, such as in the treatment and prevention of cancer, cardiovascular disease, and other pathologies. Much of the literature refers to a single group of plant phenolics, the flavonoids. This review offers an overview of the nutritional effects of the main groups of polyphenolic compounds, including their metabolism, effects on nutrient bioavailability, and antioxidant activity, as well as a brief description of the chemistry of polyphenols and their occurrence in plant foods.
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Article
Crude extracts of evening primrose meal were prepared in 56% (v/v) acetone and separated into six fractions (I-VI) using a Sephadex LH-20 column. Qualitative tests for phenolic and vanillin positive compounds produced positive results for all fractions. Silica gel thin-layer chromatography of fractions III and V allowed the location and isolation of two spots containing moderate to strong antioxidative compounds. High-performance liquid chromatography of the spot isolated from fraction III showed the resolution of two structurally related compounds, whereas that of the spot from fraction V showed the presence of one compound. Nuclear magnetic resonance spectroscopy and electron impact mass spectrometry produced sufficient evidence to identify the isolated compounds as (+)-catechin, (-)-epicatechin, and gallic acid. These compounds accounted for about 10.5 and 1.7% of the dry mass of the crude extracts and meal, respectively.
Article
Supercritical carbon dioxide (SC CO(2)) was used for the extraction of oil and squalene from Amaranthus grain. Very small amounts of oil could be extracted by SC CO(2) from undisrupted grains, although SC CO(2) possesses higher diffusivity. Grinding increased the extraction rate and oil yield, and smaller particle size gave higher extraction rate. The oil yield and initial extraction rate increased linearly with the increasing SC CO(2) flow rate from 1 to 2 L/min. Increasing the flow rate of SC CO(2) above 2 L/min resulted in only a slight increase of oil yield and extraction rate. In the pressure range of 150-250 bar, extraction decreased with increasing temperature at a constant pressure, whereas at a pressure of 300 bar, the extraction yield increased with increasing temperature. Possible reasons for this are discussed. Effects of temperature and pressure on squalene yield were different from those on oil yield. A good oil yield (4.77 g of oil/100 g of grain) was obtained at 40 degrees C and 250 bar. The highest squalene yield (0.31 g of squalene/100 g of grain) and concentration (15.3% in extract) were obtained at 50 degrees C and 200 bar, although the oil yield under this condition was low (2.07 g of oil/100 g of grain). The moisture content within 0-10% had little influence on yields of oil and squalene at 40 degrees C and 250 bar. Finally, the oil yield and the squalene concentration in the extracts by SC CO(2) were compared to those by solvent extraction.
Article
Nuts are high in fat but have a fatty acid profile that may be beneficial in relation to risk of coronary heart disease. Nuts also contain other potentially cardioprotective constituents including phytosterols, tocopherols and squalene. In the present study, the total oil content, peroxide value, composition of fatty acids, tocopherols, phytosterols and squalene content were determined in the oil extracted from freshly ground walnuts, almonds, peanuts, hazelnuts and the macadamia nut. The total oil content of the nuts ranged from 37.9 to 59.2%, while the peroxide values ranged from 0.19 to 0.43 meq O2/kg oil. The main monounsaturated fatty acid was oleic acid (C18:1) with substantial levels of palmitoleic acid (C16:1) present in the macadamia nut. The main polyunsaturated fatty acids present were linoleic acid (C18:2) and linolenic acid (C18:3). alpha-Tocopherol was the most prevalent tocopherol except in walnuts. The levels of squalene detected ranged from 9.4 to 186.4 microg/g. beta-Sitosterol was the most abundant sterol, ranging in concentration from 991.2 to 2071.7 microg/g oil. Campesterol and stigmasterol were also present in significant concentrations. Our data indicate that all five nuts are a good source of monounsaturated fatty acid, tocopherols, squalene and phytosterols.
Article
A simple and rapid reversed-phase high-performance liquid chromatography method for determination of alpha-, (beta + gamma), and delta-tocopherols in edible plant oils has been developed. Oils are diluted in 2-propanol and injected directly onto Symmetry C18 column. Methanol and acetonitrile (1:1) are used as a mobile phase. Tocopherols are detected using fluorescence detector set at excitation and emission wavelength 295 nm and 325 nm, respectively. The method is precise (R.S.D. not higher than 2.24%) and sensitive-detection limits (DL) are 8 ng/ml for gamma- and delta-tocopherols and 28 ng/ml for alpha-tocopherol; quantification limits (QL) were calculated as three times higher than DL.
Review plant sterols: Biosythesis, biological function and their importance to human nutrition
  • V. Piironen