Oxidative stabilization of cold‐pressed sunflower oil using phenolic compounds of the same seeds

It is known that sunflower seeds are rich in phenols, constituting approximately 1–3 g per 100 g of seeds. The principal phenol is chlorogenic acid (CGA), followed by caffeic acid (CA) and lower quantities of several other compounds. On the contrary, it is known that phenols are present only in trace amounts in cold‐pressed sunflower seed oils. In this study, the possibility of improving the oxidative stability of cold‐pressed sunflower oil is evaluated using phenolic substances constitutive of seeds. Phenols, extracted from two different dehulled sunflower seed samples, were identified, measured and added to a cold‐pressed sunflower oil and compared with butylated hydroxyanisole (BHA), pure CGA and pure CA. Raw phenolic extract (RPE) was composed of CGA exclusively, whereas CA was present only in traces in its free form was not present. On the contrary, hydrolysable phenol acids (HPAs) were constituted prevalently from CA, released by CGA alkaline hydrolysis. The stabilization effect on oil oxidation at 110 °C was evaluated as 41% and 118% for RPE and HPAs respectively with respect to the control. At 30 °C, no significant differences were recorded between the two seed extracts. Their antioxidant effect was lower than that at 110 °C and evaluated to be, on average 13%. In comparison with BHA, at 30 °C, both seed extracts were more effective than this synthetic phenol; at 110 °C, the antioxidant effect of RPE and BHA was similar, whereas HPA was significantly more effective than BHA. In conclusion, this study demonstrates that the phenols present in sunflower seeds can be considered natural antioxidants suitable for stabilizing the oxidation of cold‐pressed sunflower oil, at both low and high temperatures. Copyright © 2003 Society of Chemical Industry     

Isolation and Characterization of Virgin Olive Oil Phenolic Compounds by HPLC/UV and GC-MS

ABSTRACT This research examined the phenolic fraction of extra virgin olive oil samples from Lianolia variety olives grown in the region of Preveza, Greece. Phenolic compounds were extracted from oil samples, separated by reversed‐phase high‐performance liquid chromatography (HPLC), and characterized by gas chromatography‐mass spectrometry (GC‐MS). Both simple and complex phenols were detected with the latter being the most abundant. 3–4‐Dihydroxyphenyl ethanol (hydroxytyrosol) and p‐hydroxyphenylethanol (tyrosol) predominated among the simple phenols. Complex phenolic compounds were further separated by preparative HPLC and analyzed by GC‐MS before and after hydrolysis. The presence of hydroxytyrosol and tyrosol derivatives was confirmed. Both derivatives were always present in greater quantities and made up an average exceeding 70% in all samples analyzed.     

Health effects of olive oil polyphenols: Recent advances and possibilities for the use of health claims

The Mediterranean diet and consumption of olive oil have been connected in several studies with longevity and a reduced risk of morbidity and mortality. Lifestyle, such as regular physical activity, a healthy diet, and the existing social cohesion in Southern European countries have been recognised as candidate protective factors that may explain the Mediterranean Paradox. Along with some other characteristics of the Mediterranean diet, the use of olive oil as the main source of fat is common in Southern European countries. The benefits of consuming olive oil have been known since antiquity and were traditionally attributed to its high content in oleic acid. However, it is now well established that these effects must also be attributed to the phenolic fraction of olive oil with its anti‐oxidant, anti‐inflammatory and anti‐microbial activities. The mechanisms of these activities are varied and probably interconnected. For some activities of olive oil phenolic compounds, the evidence is already strong enough to enable the legal use of health claims on foods. This review discusses the health effects of olive oil phenols along with the possibilities of communicating these effects on food labels.     

水酶法提取葵花籽油工艺及机理

本研究是以脱酚的葵花籽仁为原料,主要研究了葵花籽粉碎粒径及各种水酶法提取条件等对葵花籽油提取率的影响;采用激光共聚焦显微镜(Contocal Laser Scanning Microscope,CLSM)对葵花籽粉碎过程及各相进行了表征,明确了较佳工艺条件的内在机制。研究表明,经进一步精粉碎,粒径能够达19.68 μm,游离油得率大幅提高。水酶法提葵花籽油的较佳工艺条件为:料液比1:5(w/v),添加1.5%的碱性蛋白酶Protex 6L反应2 h。该条件下,葵花籽游离油得率达到92.48%。CLSM证明精粉碎得到的葵花籽物料比剪切粉碎的尺寸更小、更均匀。水酶法提取的葵花籽油在主要理化指标上达到了冷榨一级油的标准,其反式脂肪酸显著低于市售低温压榨葵花籽油。水酶法提取的油品质更好,得油率更高,有明显的优势。     

PHENOL COMPOUNDS IDENTIFIED IN SELECTED LIQUID SMOKES

Liquid smokes including mesquite, hardwood blend, hickory (aqueous), and hickory-oil (oil-based) were subjected to direct ether extraction; phenolic components were separated and identified using gas chromatography/mass spectrometry (GC/MS). A solution containing 1,250 μg/ml each of phenol, isoeugenol, o -cresol, m -cresol, 4-allylsyringol, catechol, 4-methylcatechol, 2,6-dimethoxy-phenol, 2-methoxyphenol, 4-ethylphenol, and 2,3-dimethylphenol was injected directly or ether extracted prior to GC/MS separation for quantification of phenols in smokes and for recovery calculations. Phenol, guaiacol, syringol, and catechol in ether and ether extracted from oil were used as standards for oil-based smoke. The total amount of phenols in the smokes was similar but the proportions of individual phenols differed. Hickory smoke contained more syringol and its derivatives (4-allysyringol and 4-methylsyringol) than mesquite; mesquite contained more phenol, o-cresol, catechol and 4-methylcatechol than hickory.     

Use crude olive leaf juice as a natural antioxidant for the stability of sunflower oil during heating

Olive leaves (Kronakii cultivar) were obtained from the annual pruning of olive trees and pressed to obtain a crude juice. Aliquots from the concentrated crude olive leaf juice, representing 400, 800, 1600 and 2400 ppm as polyphenols, were added to sunflower oil. Samples of sunflower oil mixed with olive leaf juice were heated intermittently at 180 ± 5 °C for 5 h day^?1 and the heating process was repeated for five consecutive days. A control experiment was performed where butylated hydroxyl toluene (BHT) at 200 ppm was added to sunflower oil prior to intermittent heating in order to compare the antioxidant efficiency between the natural polyphenolics of olive leaf juice and synthetic antioxidant BHT. Some physical and chemical constants for the unheated and heated sunflower oil were determined. The data indicate that the addition of olive leaf juice to sunflower oil heated at 180 °C induced remarkable antioxidant activity and at 800 ppm level was superior to that of BHT in increasing sunflower oil stability.     

Impact of polyphenols from banana pseudostem on sunflower oil stability

The present investigation is focused on the potential use of banana pseudostem, which otherwise is disposed off as a waste, as a source of polyphenols or antioxidants. The polyphenols extracted from the outer leaf sheaths of 3 Indian banana (Musa spp.) cultivars namely, ‘Nendhran’, ‘Robusta’, and ‘Kathali’ were tested for antioxidant activities. The extracts showed effective DPPH, hydroxyl, and superoxide radical scavenging ability. Among the banana cultivars, ‘Nendhran’ followed by ‘Robusta’ contained the highest total phenolic (110.45 and 94.03 mg GAE/g extract, respectively) and total flavonoid (49.62 and 38.61 mg QE/g extract, respectively) contents and antiradical activity. Further, the study was aimed to evaluate the protective effects of the polyphenolic extracts in stabilizing sunflower oil, tested in terms of peroxide value, free fatty acid contents, and p-anisidine values in comparison with the synthetic antioxidants, butylated hydroxyanisole and butylated hydroxytoluene. In addition, the antioxidant activity and total phenolic contents of the extract-treated oil samples were also monitored to obtain a complete perspective of the influence exerted by the polyphenols in oil stability. The results demonstrated that polyphenols from pseudostem of banana cultivars are potent source of natural antioxidants and might serve as a substitute for synthetic antioxidants in oil industry.     

Chemical Components and Antioxidant Activity of the Peels of Commercial Apple‐Shaped Pear (Fruit of Pyrus pyrifolia cv. pingguoli)

Abstract: The apple‐shaped pear, the fruit of the Pyrus pyrifolia cv. pingguoli (Rosaceae) tree, is one of the most popular fruits in the northern part of China. The current study is the 1st report of its bioactive components. We identified 10 metabolites from the peels (exocarp) of apple‐shaped pear and assessed their toxicity. We then compared the anti‐oxidant activity, amount of total phenolic compounds, and total condensed tannin content of the peels and flesh (mesocarp) of apple‐shaped pear. The 6 major components in the peels and flesh of this fruit were quantified with Ultra Performance Liquid Chromatography–Electrospray Ionization Mass Spectrometry. Results revealed that the peels possessed stronger anti‐oxidant activity and contained larger amounts of phenolic compounds than the flesh. These results provide insights into the potential health benefits of this fruit and support the use of the fruit peels and products containing peels or peel components. Practical Application: The present research provided evidences that the pulp and peel waste from the juice industry of apple‐shaped pear may be a source of useful compounds.     

Phenolic and antioxidant potential of olive oil mill wastes

Olive oil mill waste was subjected to conventional liquid solvent extraction and supercritical fluid extraction using different solvents and carbon dioxide, respectively. The optimum solvent extraction conditions of phenols were 180 min using ethanol, at a solvent to sample ratio 5:1 v/w, and at pH 2. Solvent and SFE extracts were tested for their antioxidant activity by the DPPH radical scavenging method and by determination of peroxide value on virgin olive oil and sunflower oil. The ethanol extract exhibited the highest antiradical activity, and no correlation was found between antiradical activity and phenol content. The SFE extract exerted good antioxidant capacity although its phenolic yield was not quite high. Moreover, the ethanol extract appeared to be a stronger antioxidant than BHT, ascorbyl palmitate and vitamin E by the Rancimat method on sunflower oil. HPLC analysis of the extracts showed that the predominant phenolic compound was hydroxytyrosol. Various phenolic acids and flavonoids were also identified.     

Antioxidant Activity of Pea (Pisum sativum L.) Seed Coat Acetone Extract

The contents of phenolic compounds in seed coat of pea and their antioxidative properties were examined. The pea seed coat was extracted with acetone-water (7:3 v/v) mixture and the extract was separated into five (?V) fractions using a Sephadex LH-20 column chromatography. Antioxidative activity of extract and fractions was measured by the oxidation of phosphatidylcholine to hydroxyperoxidephosphatidylcholine in liposome model and by scavenging effects of superoxide radical anion in xanthine-xanthine oxidase system. Phenolic compounds of extract and fractions were determined by spectrophotometric methods and characterized by HPLC analysis. Strong antioxidative properties were noted for extract and its five fractions measured by liposome method. The extract and fractions I, IV and V also showed scavenging effects of superoxide radical anion. A statistically significant correlation (P≤0.05) was found between the inhibition of PC oxidation in the system tested and contents of either total phenols or tannins. However no statistically significant correlation was found between O^•−₂ scavenging effect and contents of either total phenols or tannins. The HPLC analysis of phenolic compounds of extract and active fractions showed the presence of some phenolic acids (benzoic and cinnamic acids, and cinnamic acid derivatives), flavone and flavonol glycoside.     

On the extraction and antioxidant activity of phenolic compounds from winery wastes

Winery waste (from red winemaking, variety Agiorgitiko) was extracted under various conditions using different solvents. The minimum time required for ensuring maximum extraction of phenols was 180 min at a solvent to sample ratio 9:1 v/w and at pH 1.5. The antioxidant activity of solvent extracts was investigated by DPPH radical scavenging method, by determination of peroxide value on virgin olive oil and by the Rancimat method on sunflower oil. Ethanol extract exhibited the highest antioxidant activity compared to the other solvent extracts, to synthetic food antioxidants BHT, ascorbyl palmitate and to the natural food antioxidant, vitamin E. No correlation was found between antioxidant activity and total phenol content. HPLC analysis of the extracts showed that gallic acid, catechin and epicatechin were the major phenolic compounds in winery waste. Hydroxytyrosol, tyrosol, cyanidin glycosides and various phenolic acids such as caffeic, syringic, vanillic, p-coumaric and o-coumaric acids were also identified.     

In vitro digestibility of phenolic compounds from edible fruits: could it be explained by chemometrics?

The health benefits of phenolic compounds depend on the ingested amount, molecular diversity and gastrointestinal digestibility. The phenolic profile of eight fruits (blackberry, blueberry, strawberry, raspberry, mulberry, pomegranate, green and red globe grapes) was chemometrically associated with their in vitro digestibility (oral, gastric, intestinal). Extractable phenols, flavonoids and anthocyanins strongly correlated with each other (r ≥ 0.84), proanthocyanidins with anthocyanins (r = 0.62) and hydrolysable phenols with both extractable phenols (r = 0.45) and proanthocyanidins (r = ?0.54). Two principal components explained 93% of the variance [61% (free‐phenols), 32% (bounded‐phenols)], and four clusters were confirmed by hierarchical analysis, based in their phenolic richness (CLT 1‐4: low to high) and molecular diversity. In vitro digestibility of extractable phenols and flavonoids was blackberry (CLT‐4)> raspberry (CLT‐2)> red grape (CLT‐1) related to their phenolic richness (r ≥ 0.96; P < 0.001), but anthocyanins’ digestibility was pH‐dependent. Chemometrics is useful to predict the in vitro digestibility of phenolic compounds in the assayed fruits.     

Contribution of olive seed to the phenolic profile and related quality parameters of virgin olive oil

BACKGROUND: Conflicting results have been reported about the effect of fruit de‐stoning on the virgin olive oil (VOO) phenolic profile. The aim of the present study was to determine whether olive seed plays any role in the synthesis of this oil phenolic fraction. RESULTS: Increases of around 25% of total phenolic compounds were observed in oils obtained from de‐stoned olive fruits in three main Spanish cultivars. To investigate the involvement of olive seed in determining the phenolic profile of VOO, whole intact olive fruits were added with up to 400% olive stones. Excellent regression coefficients were found in general for the decrease of total phenolic compounds and, particularly, of o‐diphenolics in the resulting oils. On the other hand, it was found that olive seed contains a high level of peroxidase (POX) activity (72.4 U g^?1 FW), accounting for more than 98% of total POX activity in the whole fruit. This activity is able to modify VOO phenolics in vitro, similar to the effect of adding stones during VOO extraction. CONCLUSION: Olive seed plays an important role in determining VOO phenolic profile during the process to obtain an oil that seems to be associated with a high level of POX activity. Copyright © 2007 Society of Chemical Industry     

Pro- or antioxygenic activity of tejpat (Cinnamomum tamala) and red chilli (Capsicum annum) in sunflower oil

The pro- or antioxygenic activity of tejpat and red chilli, their fractions extracted using various solvents, and of chlorophyll, capsaicin and dihydrocapsaicin were determined in refined sunflower oil at 37 °C. Tejpat and its fractions containing chlorophyll showed pro-oxygenic activity and the catalytic action increased with increase in concentration of chlorophyll in the fractions. On the other hand, fractions which did not contain chlorophyll, such as the aqueous extract, and chlorophyll-free spice or fractions freed of chlorophyll by column chromatography were devoid of pro-oxygenic activity. The ground red chilli and its 80:20 (v/v) ethanol/water fraction exhibited strong antioxygenic activity. On the other hand, the petroleum ether fraction showed marginal antioxygenic activity, whereas the water-soluble fraction was practically devoid of any activity in refined sunflower oil. The pungent constituents of red chilli, capsaicin and dihydrocapsaicin also exhibited considerable antioxygenic activity. © 1999 Society of Chemical Industry     

Effect of Natural Extracted Antioxidants from Eriobotrya japonica (Lindl.) Fruit Skin on Thermo Oxidative Stability of Soybean Oil During Deep Frying

The effects of ultrasound-assisted, supercritical CO₂ and solvent extraction techniques on antioxidant activity of Eriobotrya japonica (Lindl.) skin extracts were investigated using 2, 2-diphenyl-1-picrylhydrazyl, β-carotene, and Rancimat assays. Solvent extract of skin at 400 ppm had the highest antioxidant activity. Solvent extraction was the most effective method on extraction of phenols and tocopherols. Protective effects of extracts in stabilization of soybean oil during frying were determined by measuring its peroxide value, total polar compounds, carbonyl value, free fatty acids, conjugated dienes, and trienes. Results indicated that solvent extract of skin at 400 ppm exhibited stronger antioxidant activity in oil than tertiary butylhydroquinone.     

宁夏枸杞子极性提取物在食用油高温氧化中的作用研究

利用95%乙醇提取宁夏枸杞子的极性物质。采用Schaal法研究了宁夏枸杞子极性提取物在食用油高温氧化过程中的作用。研究表明,枸杞子极性提取物对猪油、葵花籽油的氧化均具有良好抑制作用。     

Anti-oxidant content of different coloured sweet peppers, white, green, yellow, orange and red (Capsicum annuum L.)

Five different coloured sweet peppers (Capsicum annuum cv. Signal), white, green, yellow, orange and red were analysed for total carotenoids, α‐tocopherol, sugars (glucose, fructose and sucrose), organic acids (citric and ascorbic acids) and anti‐oxidant properties. The mature fruits, ‘Signal Red’, ‘Signal Orange’ and ‘Signal Yellow’ contained higher carotenoids, α‐tocopherol, sugars and organic acids than the immature fruits, ‘Signal Green’ and ‘Signal White’. Among the mature fruits, ‘Signal Red’ was the highest in total carotenoids [9.15 mg (100 g)^?1 of fresh weight] while ‘Signal Orange’ was the highest in α‐tocopherol [5.40 mg (100 g)^?1 of fresh weight]. ‘Signal Red’ and ‘Signal Orange’ contained the most sugars and organic acids. The suppression of 2,2′‐azobis (2,4‐dimethylvaleronitrile) (AMVN)‐induced oxidation of methyl linoleate by the acetone extracts from the coloured sweet peppers resulted as follows: ‘Signal Red’ > ‘Signal Orange’ ≈ ‘Signal Yellow’ > ‘Signal Green’ ≈ ‘Signal White’. The order of 1,1‐diphenyl‐2‐picrylhydrazyl (DPPH) radical scavenging activities of the acetone extracts was similar to that of suppression of methyl linoleate oxidation.     

Egyptian mango by-product 2: Antioxidant and antimicrobial activities of extract and oil from mango seed kernel

Egyptian mango seeds were collected as wastes from local fruit processing units, the kernels were separated and dried. The antioxidant and antimicrobial activities of mango seed kernel extract and oil were investigated. The results indicated that combination of both mango seed kernel extract and oil had optimum antioxidant potency higher than each one alone. Addition of 400 ppm methanol extract and 5% mango seed kernel oil increased the oxidative stability of sunflower oil incubated at ambient temperature as well as sunflower oil during frying. Moreover, both extract and oil improved the stability and quality characteristics of fresh and stored potato chips. On the other hand, mango seed kernel extract reduced total bacterial count, inhibited coliforms growth, showed remarkable antimicrobial activity against Escherichia coli strain and extended the shelf-life of pasteurized cow milk. These results provide useful information on the utilization of mango seed kernel as natural antioxidant and antimicrobial in foods.     

Phenolic extracts from Crataegus × mordenensis and Prunus virginiana: Composition,antioxidant activity and performance in sunflower oil

The prevailing stigmatization of synthetic antioxidants and the inefficiency of endogenous antioxidants like tocopherols during high temperature processing of edible oils necessitate the search for effective natural antioxidants. Here, polyphenolic extracts from chokecherry and hawthorn fruits were screened for possible antioxidative application in fats/oils. Extracts were successively partitioned on sephadex columns and fractions were screened for radical scavenging activity using DPPH and β-carotene assays. Furthermore, sunflower oil fortified with extracts was assessed for stability using accelerated storage at 65 °C, Rancimat at 120 °C, and frying at 180 °C. Phenolic extracts showed significantly high radical scavenging and antioxidant activity in the oil. At the end of storage, hydroperoxide formation in sunflower oil was reduced by up to 50%, and the induction period significantly increased in the presence of extracts. Similarly, a significantly high frying stability was observed for the fortified samples, suggesting that the phenolic extracts can offer effective natural alternative to synthetic antioxidants during frying.     

宁夏枸杞子非极性提取物在油脂高温氧化中的作用及机理

利用四氯化碳提取宁夏枸杞子的非极性物质。采取Schaal烘箱法研究枸杞子非极性提取物在食用油氧化过程中的作用。结果表明低浓度的非极性提取物对葵花籽油具有良好的氧化抑制作用,对猪油的氧化没有抑制效果;高浓度非极性提取物对猪油、葵花籽油均具有氧化促进作用。