Effect of total solids content in feed emulsion on the physical properties and oxidative stability of microencapsulated kenaf seed oil

Kenaf (Hibiscus cannabinus L.) seed oil has high potential to be used as edible oil. Despite the high content of polyunsaturated fatty acids, one of the major complications in commercialisation kenaf seed oil is its rapid oxidation, which leads to the production of undesirable toxic substances such as peroxides. The objective of this study was to investigate the effect of total solids content (TSC) on the oxidative stability of microencapsulated kenaf seed oil (MKSO) and to compare its oxidative stability with bulk kenaf seed oil upon accelerated storage. Microcapsules with 20%, 30% and 40% total solids content were prepared. Physical properties, such as the emulsion characteristics and microcapsules characteristics were also studied. Results showed that bulk kenaf seed oil was oxidised to a greater extent compared to the microencapsulated samples. The results showed that 40% total solids content microcapsules had the lowest peroxide value (PV), p-anisidine value (AnV), total oxidation (TOTOX) value and free fatty acid (FFA) value, which were 3.70 ± 0.83 meq O₂/kg oil, 16.12 ± 0.19, 23.52 ± 1.67 and 2.54 ± 0.06%, respectively. The microencapsulation of kenaf seed oil showed protective effect against lipid oxidation.     

Optimization of Bleaching Parameters in Refining Process of Kenaf Seed Oil with a Central Composite Design Model

Kenaf seed oil has been suggested to be used as nutritious edible oil due to its unique fatty acid composition and nutritional value. The objective of this study was to optimize the bleaching parameters of the chemical refining process for kenaf seed oil, namely concentration of bleaching earth (0.5 to 2.5% w/w), temperature (30 to 110 °C) and time (5 to 65 min) based on the responses of total oxidation value (TOTOX) and color reduction using response surface methodology. The results indicated that the corresponding response surface models were highly statistical significant (P < 0.0001) and sufficient to describe and predict TOTOX value and color reduction with R² of 0.9713 and 0.9388, respectively. The optimal parameters in the bleaching stage of kenaf seed oil were: 1.5% w/w of the concentration of bleaching earth, temperature of 70 °C, and time of 40 min. These optimum parameters produced bleached kenaf seed oil with TOTOX value of 8.09 and color reduction of 32.95%. There were no significant differences (P > 0.05) between experimental and predicted values, indicating the adequacy of the fitted models.     

Effect of Extrusion Processing on Antioxidant Activities of Corn Extrudates Fortified with Various Chinese Yams (<Emphasis Type="Italic">Dioscorea</Emphasis> sp.)

The purpose of this experiment was to evaluate the effects of extrusion on antioxidant abilities of the extrudates of corn fortified with various (Chinese) yams. The flours from three yam varieties were used, including Dioscorea alata L. var. Tai-nung No.1 (TN1), D. alata L. var. Ta-shan (TS), and Dioscorea doryophora var. Hang-chun (HC). One commercial yam flour (TJ) was also used. Six antioxidant assays were conducted, such as 1,1-diphenyl-2-picryl-hydrazyl (DPPH) free radical scavenging effect, oxygen radical absorbance capacity (ORAC) assay, ferrous ion chelating (FIC) ability, 2,2-azino-bis-(3-ethylbenzothiazoline-6-sulphonic acid) (ABTS) free radical scavenging activity, superoxide radical scavenging (SORS) assay, and thiobarbituric acid reactive substances (TBARS) assay. The influences of extrusion on the antioxidant activities of corn were determinedly different in different assays, showing a dramatic increase of ABTS value but significant reductions of SORS and TBARS values. The effects of extrusion on antioxidant activities of corn–yam mixtures varied with yams in different assays. Overall, extrusion processing increased the TBARS inhibition ability for all yams and generally had no negative impact on DPPH, ORAC, FIC, and ABTS antioxidant abilities for most yams in corn–yam extrudates. The involvement of the addition of yam to the antioxidant activities of corn–yam extrudates during extrusion could be suggested through two different possible approaches, the effects of extrusion on the antioxidant activities of yams (susceptible, resistant, or improved), and the effects of added yams on the antioxidant activities of corn during extrusion.     

Beneficial effect of the unsaponifiable matter from rice bran on oxidative stress in vitro compared with α‐tocopherol

Unsaponifiable matter (UM) was prepared from rice bran using n‐hexane extraction followed by removal of its fatty acid methyl ester with supercritical CO₂ under heat‐stable conditions. The UM was made up of 1% of vitamin E isomers, 28% of γ‐oryzanol and 71% of uncharacterized compounds. The aim of this study was to determine the antioxidant activities of the UM, using α‐tocopherol (α‐T) as a positive control, by measuring the Fe³⁺‐reducing antioxidant power (FRAP), 2,2‐diphenyl‐1‐picrylhydrazyl (DPPH^?) free‐radical‐scavenging property and lipid peroxidation in rat liver microsomes. In addition, the effects of the UM on the tert‐butyl hydroperoxide (t‐BOOH)‐induced cytotoxicity in cultured rat hepatocytes were also investigated. In FRAP assay and DPPH^? free‐radical‐scavenging assay, the results were expressed g^?1α‐T or g^?1 UM. The amount of UM used in lipid peroxidation assay and cytotoxicity assay was the amount required to have equal amounts of total vitamin E isomers in the sample and the control α‐T. The UM, as well as α‐T, exhibited significant antioxidant activities in FRAP, radical‐scavenging and membrane‐lipid oxidation. The FRAP value for total vitamin E isomers in the UM (TVEIUM) was 9.1 times higher than that for α‐T. In terms of their capacities to perform radical‐scavenging and lipid peroxidation, both TVEIUM and α‐T showed similar antioxidant activities. In experiments using cultured rat hepatocytes, the t‐BOOH‐induced lactate dehydrogenase release was significantly inhibited by the addition of 63.5 and 160 µg ml^?1 of TVEIUM treatments (84 and 89%, respectively), and that of 63.5 and 160 µg ml^?1 of α‐T treatment (88 and 93%, respectively). The antioxidant function against oxidative stress of the UM prepared from rice bran may extend its use to being a potential dietary supplement. Copyright © 2004 Society of Chemical Industry     

Antioxidant Activity of Various Solvent Fractions from Edible Brown Alga,Eisenia bicyclis and Its Active Compounds

In this study, we aimed to elucidate the antioxidant capacity of Eisenia bicyclis and evaluated its antioxidant activity using various assay systems such as 2,2‐diphenyl‐1‐picrylhydrazyl (DPPH) radical scavenging, 2,2‐azino‐bis (3‐ethylbenzthiazoline‐6‐sulfonic acid) (ABTS) radical scavenging, reducing power ability, and content of total polyphenol. Among all the performed experiments, the ethyl acetate fraction of E. bicyclis exhibited higher antioxidant activities. From this finding, isolation and purification were performed on the ethyl acetate fraction and identified dieckol and phlorofucofureoeckol‐A by spectroscopic analyses including FAB‐mass in the negative mode, ¹H NMR, ¹³C NMR, ¹H‐¹H COSY, HMQC, and HMBC spectra. Interestingly, ABTS radical scavenging activities of dieckol and phlorofucofuroeckol showed strong effects of 65.36% and 70.38% at a concentration of 50 μg/mL, respectively. DPPH radical scavenging and reducing power abilities were increased in a dose‐dependent manner at various concentrations. These results suggest that dieckol and phlorofucofuroeckol‐A of E. bicyclis may play an important role in protection from oxidative stress involving reactive oxygen species and may contribute to the development of new bio products, for example, a useful preservative to improve food quality and a drug for various oxidative damage‐associated diseases. Practical Application: The results suggest that dieckol and phlorofucofuroeckol‐A can be utilized as a natural source for potential application of antioxidant in food industry and drug for oxidative damage‐associated diseases.     

Natural volatile treatments increase free‐radical scavenging capacity of strawberries and blackberries

Free‐radical scavenging capacities of strawberries and blackberries treated with methyl jasmonate (MJ), allyl isothiocyanate (AITC), essential oil of Melaleuca alternifolia (tea‐tree oil or TTO), and ethanol (EtOH) were investigated. All of these natural volatiles tested reduced the severity of decay in both strawberries and blackberries during storage at 10 °C as compared to the control. Most of these compounds enhanced antioxidant capacity and free‐radical scavenging capacity, except the AITC treatment. The MJ treatment for strawberries and blackberries had the highest antioxidant capacity, expressed as oxygen radical absorbance capacity (ORAC) values, after 7 days of storage. Moreover, the MJ treatment promoted the antioxidant capacity in strawberries and blackberries as measured by the radical 2,2‐di (4‐tert‐octylphenyl) ‐1‐picrylhydrazyl (DPPH) and the radical cation 2,2′‐azinobis(3‐ethylbenzothiazoline‐6‐sulfonic acid) diammonium salt (ABTS^?+) scavenging activity in both 7 and 14 days after storage. The MJ treatment also increased scavenging capacities on the superoxide radical (O₂^??), hydrogen peroxide (H₂O₂), hydroxyl radical (^?OH), and singlet oxygen (¹O₂) in strawberries and blackberries. Treatment with TTO or EtOH enhanced most of these free‐radical scavenging capacities, except for H₂O₂ in strawberries, and for O₂^?? and ¹O₂ in blackberries. These results indicated that all of the natural volatile compounds tested in this study, except AITC, promoted the antioxidant capacity and scavenging capacity of most major free radicals and, thus, helped to improve the physiology of berry fruits and enhanced their resistance to decay. While AITC was also very effective in reducing decay, its effect on free‐radical scavenging capacity was inconsistent, suggesting that additional mechanisms may be involved in its inhibition of fungal growth. Copyright © 2007 Society of Chemical Industry     

Nutritional analysis and antioxidant activity of palmyrah (<Emphasis Type="Italic">Borassus flabellifer</Emphasis> L.) seed embryo for potential use as food source

The present study was carried out with ungerminated seed embryos of palmryah to evaluate nutritional quality with respect to minerals and fiber components, total phenols, and antioxidant properties. It is found to be good source of carbohydrate, fiber, fat, amino acids, and protein. Analysis of macro and micronutrient composition showed potent source of sodium, potassium, calcium, magnesium, zinc, and iron. In vitro antioxidant activity was evaluated by different assays, including 2,2-diphenylpicryl-1-picrylhydrazyl (DPPH) radical scavenging, 2,2′azinobis (3-ethylbenzothiozoline-6-sulfonic acid) disodium salt (ABTS^·+) assay, ferric reducing antioxidant power (FRAP) assay, phospomolybdenum reduction assay, metal chelating activity, and hydroxyl radical scavenging activity. The results indicate that this plant seed embryo possesses micro, macro nutrients and antioxidant properties and has nutraceuticals potential for the treatment of malnutrition.     

Antioxidant,free radical scavenging and type II diabetes‐related enzyme inhibition properties of traditionally processed Jequirity bean (Abrus precatorius L.)

The methanolic extract of raw Abrus precatorius (Jequirity bean, red‐ and black‐coloured seed coat) seeds contains a total phenolic content of 14.2 ± 0.39 g catechin equivalent/100 g extract. An analysis of phenolic profile revealed the presence of syringic acid, caffeic acid and (?)‐epicatechin in the methanolic extract of A. precatorius seeds. Encouraging levels of ferric reducing/antioxidant power (FRAP, 1247 mmol Fe[II]/mg extract), inhibition of β‐carotene bleaching (53.37%), 2,2‐Diphenyl‐1‐picryl‐hydrazyl (DPPH, 62.13%) and superoxide (64.47%) radical scavenging activities were exhibited by the extract of raw samples. Inhibition characteristics of 68.69%α‐amylase and 51.74%α‐glucosidase enzyme were also recorded under in vitro starch digestion bioassay. Sprouting + oil‐frying caused a significant increase in the total phenolic content and also substantially improved the antioxidant and free radical scavenging capacities, while soaking + cooking as well as open‐pan roasting treatments showed diminishing effects.     

Enzymatic Synthesis of l‐Ascorbyl Fatty Acid Esters Under Ultrasonic Irradiation and Comparison of Their Antioxidant Activity and Stability

A series of novel l ‐ascorbyl fatty acid esters were synthesized by catalization of Novozym^® 435 under ultrasonic irradiation and characterized by infrared spectroscopy, electrospray ionization mass spectra, and nuclear magnetic resonance. Their properties especially antioxidant activity and stability were investigated. The results showed that the reducing power, the scavenging activity of hydroxyl radical and 2,2‐diphenyl‐1‐picrylhydrazyl radical were decreased with the increase of the number of carbon atoms in fatty acid. The hydroxyl radical scavenging activity and reducing power of l ‐ascorbyl saturated fatty acid esters were better than that of tert‐butylhydroquinone. The induction period in lipid oxidation of l ‐ascorbyl saturated fatty acid esters and tert‐butylhydroquinone were longer than that of l ‐ascorbyl unsaturated fatty acid esters and l ‐ascorbic acid both in soybean oil and lard. Besides, the l ‐ascorbyl fatty acid esters showed different stabilities in different conditions by comparing with l ‐ascorbic acid, and the l ‐ascorbyl saturated fatty acid esters were more stable than l ‐ascorbyl unsaturated fatty acid esters in ethanol solution.     

Volatile compounds and oxidative stability of Pinus halepensis Mill. seed oil under heating conditions

Heating conditions of Pinus halepensis seed oil were monitored to evaluate the effect of thermo‐oxidation processes on the bioactive compounds contained in the samples. The following parameters were monitored: ultra violet absorption at 232 and 270 nm, fatty acid composition, oxidative stability, antiradical activity and aromatic profiles. Under thermo‐oxidation process, trans fatty acids (TFA) increased and conjugated linoleic acid isomers appeared. The antiradical activity significantly decreased from 73.3% to 52.5% after 120 min of heating. Oxidative stability decreased (r = ?0.70). The volatile profile was heavily influenced by heating with the formation of new volatile compounds, such as the two isomers (E,Z)‐2,4‐decadienal and (E,E)‐2,4‐decadienal. α‐pinene, and the main terpene compound was very vulnerable to heating conditions. Despite its peculiar pleasant aroma and nutritional value, the P. halepensis seed oil should not be used for cooking. Indeed, under frying conditions, its antioxidant properties and oxidative stability are lost and potential toxic compounds, such as TFA and unsaturated aldehydes, are formed.     

Broccoli seed extracts but not sulforaphane have strong free radical scavenging activities

The abilities of broccoli seed extracts and purified sulforaphane (SF) to scavenge 2,2′‐azinobis [3‐ethylbenzothiazoline‐6‐sulphonate] (ABTS^?+), 2,2‐diphenyl‐1‐picrylhydrazyl (DPPH^?) and superoxide anions were studied. The free radical scavenging activities of broccoli seed extracts had no exact correlation with SF content, indicating that SF was not the main antioxidant component. The broccoli seed extracts were separated by high‐speed countercurrent chromatography to obtain purified SF, which showed dose‐dependent free radical scavenging activities in the DPPH^? and ABTS^?+ assays, but its activities were weaker to those of ascorbic acid. The same trend was observed in the chemiluminescence assay. The results showed that broccoli seed extracts had strong free radical scavenging activities that were not attributable to SF.     

Comparative study of crude and refined kenaf (<Emphasis Type="Italic">Hibiscus cannabinus</Emphasis> L.) seed oil during accelerated storage

This study assessed the changes of antioxidant activity and bioactive compounds of crude and refined kenaf seed oil during accelerated storage at 65°C for 24 days. 2,2-Diphenyl-1-picrylhydrazyl and 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) radical scavenging assays were used to determine their antioxidant activity. The changes of phenolic, tocopherol, and phytosterol contents during the storage were also studied. The phenolic content and antioxidant activity of refined oil were significantly lower than those of crude oil after the accelerated storage. There was a decrease of 72.5% tocopherol content and 31.1% phytosterol content in the crude oil and a decrease of 67% tocopherol content and 12.1% phytosterol content in the refined oil during the accelerated storage. There was no significant difference in tocopherol and phytosterol contents for crude and refined oils after the storage. The rate of degradation of tocopherol and phytosterol contents in refined oil was slower than that in crude oil during the storage.     

Oxidative stability of camelina oil in salad dressings,mayonnaises and during frying

Oxidative stability of omega‐3 rich camelina oil in food products and during frying was evaluated and compared with sunflower oil. Camelina oil‐based salad dressings were of similar oxidative stability to those prepared with sunflower oil, as indicated by predominantly insignificant (P > 0.05) differences in peroxide values (PV), ρ‐anisidine values (AV), total oxidation values (TOTOX), conjugated diene levels (CD) and conjugated triene levels (CT). However, thiobarbituric acid reactive substances (TBARS) were significantly higher (P < 0.05) for camelina oil and salad dressings throughout storage. Camelina and sunflower oils, alone and in salad dressings or mayonnaises, were acceptable to a sensory analysis panel with slightly lower scores for camelina oil. PV, AV and TOTOX values were similar for camelina and sunflower oil during deep frying but while PVs remained low (<10 meq kg^?1), AV and TOTOX values increased quickly. TBARS values were significantly higher in deep‐frying camelina oil and ‘fishy’ odours were observed.     

Peroxyl radical‐trapping capacity of germinated legume seeds

The legume seeds of lentil (Lens culinaris( vetch (Vicia sativa) and soybean (Glycine max, cv. Mazowia) were germinated in the dark at a constant temperature of 25°C up to 168 h (24 h×7 d). The changes in peroxyl radical‐trapping capacity (PRTC) of the processed seeds were measured and compared to those of the raw seeds. A simple method of determining the peroxyl radical‐trapping capacity based on the use of 2,2′‐azobis(2‐amidopropane) hydrochloride (ABAP) decomposition as a free radical source and the use of 2,2′‐azinobis(3‐ethylbenzothiazoline‐6‐sulfonic acid) (ABTS) oxidation as the reaction indicator was employed to express antioxidant properties of germinated seeds. The data show that the germinated lentil and vetch seeds were more effective than germinated soybean when their peroxyl radical‐trapping capacity was compared.     

Effect of refining on the lignan content and oxidative stability of oil pressed from roasted sesame seed

Oxidative stability of pressed and refined sesame oils during seven consecutive months of storage at room temperature was studied comparatively. Lignans, peroxide value (PV), p‐anisidine value (AV) and total oxidation value (TOTOX) were determined as evaluation indices. PV, AV and TOTOX of sunflower, corn and peanut oils were simultaneously monitored to compare their oxidative storage stabilities with the sesame oils. The total amount of lignans in the pressed and refined sesame oils were 1103 and 790 mg per 100 g respectively. The contents of sesamin and sesemolin in the pressed sesame oil were 734 and 369 mg per 100 g respectively. Sesamin and sesamolin content were reduced by 256 and 159 mg per 100 g, respectively, after refining. Nearly 40% of the sesamin epimerised to asarinin after oil refining. The results indicate that sesame oils pressed from roasted seed have far superior storage stability to oxidation than the other vegetable oils. This difference may be due to much higher sesamin and sesamolin contents in the pressed sesame oils. The results suggest lignan compositions and levels could be used as key indicators for evaluating the oxidative storage stability of sesame oil products as well as to differentiate between pressed and refined sesame oils.     

Effects of adlay seed oil on blood lipids and antioxidant capacity in hyperlipidemic rats

BACKGROUND: Adlay (Coix lacryma‐jobi L. subsp. ma‐yuen (Romanet) T. Koyama (family Poaceae)) seed has been used as a dietary supplement for its therapeutic effects for thousands of years. This study was designed to investigate the effects of adlay seed oil, obtained by supercritical CO₂ extraction, on blood lipids and antioxidant capacity in hyperlipidemic rats. RESULTS: Adlay seed oil could reduce the abdominal fat tissue and low‐density lipoprotein concentration, and increase the total antioxidant capacity in hyperlipidemic rats. Adlay seed oil also significantly decreased the malondialdehyde content in serum, and increased serum total superoxide dismutase activity in hyperlipidemic rats. Therefore, the antioxidant mechanism might be related to the scavenging effects of adlay seed oil on reactive oxidative species, especially on the superoxide anion free radical. CONCLUSION: The results showed that adlay seed oil had blood lipid‐reducing and antioxidant effects, and could be used as a supplement in healthcare food and drugs for the prevention of chronic diseases (especially artherosclerosis and coronary artery disease). Copyright © 2011 Society of Chemical Industry     

Antioxidant Activities of Polyphenolic Compounds Isolated from Antidesma thwaitesianum Müll. Arg. Seeds and Marcs

ABSTRACT: Antidesma thwaitesianum Müll. Arg. or mao is widely used as commercial products of juice and wine in Thailand. As a result, waste products from the mao plant, such as mao seeds (MS) and mao marcs (MM), are plentiful. We aimed to purify and analyze polyphenolic content in both MS and MM and to investigate the radical scavenging activities of these polyphenolics against 1,1‐diphenyl‐2‐picryl‐hydrazyl (DPPH) and 2,2′‐Azinobis (3‐ethylbenzothiazoline 6‐sulphonate) (ABTS) radicals and thiobarbituric acid reactive products (TBARP). The results showed MS and MM to be an abundant source of polyphenols (97.32 to 130 mg gallic acid equivalents [GAE]/g) and proanthocyanidins. The radical scavenging activities of MS/MM against DPPH and ABTS radicals (IC₅₀ of 0.85 to 1.21 μg/mL) were significantly higher (P < 0.05) than that of standard trolox (IC₅₀ of 5.05 μg/mL). Activity of MS/MM extracts were 3.74 and 3.80 μg/mL trolox eq/g f.w. for the DPPH and ABTS assays, respectively. The oxidation of erythrocyte membranes using 2‐thiobarbituric acid demonstrated that the protective effect of MS/MM on lipid peroxidation is as strong as grape seed proanthocyanidin extract. These findings suggest that polyphenolic compounds and proanthocyanidins isolated from these mao extracts had much higher antioxidant activities than those of standard trolox and exhibited similar antioxidant potential to grape seed proanthocyanidin extract. These findings may also increase value of mao waste products and allow development of commercial health products.     

Antioxidant Capacities,Phenolic Contents,and GC/MS Analysis of Rhodiola imbricata Edgew. Root Extracts from Trans‐Himalaya

Our aim was to assess the antioxidant capacities and phenolic constituents of methanol and aqueous extracts of Rhodiola imbricata Edgew. root from Trans‐Himalayan cold desert of Ladakh. The 1,1‐diphenyl‐2‐picrylhydrazyl (DPPH) and 2,2′‐azinobis‐(3‐ethylbenzothiazoline‐6‐sulfonic acid (ABTS) radical scavenging capacity of the root extracts increased in a dose‐dependent manner (up to 0.1 mg/mL) and root extract concentrations required for 50% inhibition of radical scavenging effect (IC₅₀) were recorded as 0.013 and 0.014 mg/mL (for DPPH) and 0.016 and 0.017 mg/mL (for ABTS) for methanol and aqueous extracts, respectively. The total antioxidant power of the extract was determined by ferric reducing antioxidant power (FRAP) assay. Total polyphenol and phenolic acid content of methanol and aqueous extracts were 112.24, 59.06, 39.02, and 16.95 mg gallic acid equivalent/g of extract, respectively. Total flavonoid and flavonol contents were estimated to be 30.2, 17.67, 20.68, and 7.38 mg quercetin equivalent/g of extract, respectively. In all antioxidant capacity assays, the methanol extract exhibited significantly higher antioxidant capacity than that of aqueous extract due to the presence of significantly higher amount of vital phytoconstitiuents, viz. polyphenol, phenolic acid, and flavonol. GC/MS analysis showed that phytosterols, alkyl halide, phenols, and fatty acid esters were major phytochemical clusters. On the other hand, monoterpenes, fatty acids, tocopherols, aliphatic hydrocarbons, and ethers were found to be present in comparatively less amount in the methanol extract. Hence, our study signifies that this high‐altitude medicinal herb could be used as the natural source of antioxidants and supports its use in traditional system of medicine to ameliorate oxidative stress and high‐altitude maladies.     

Chemical Acylation of Water‐Soluble Antioxidant of Bamboo Leaves (AOB‐w) and Functional Evaluation of Oil‐Soluble AOB (cAOB‐o)

Antioxidant of bamboo leaves (AOB) is a novel natural food antioxidant approved in China since 2004. Natural phenolics contained in the current AOB are usually polyhydroxy derivatives exhibiting hydrophilic character, which has been marked as water‐soluble AOB (AOB‐w). In order to broaden the application fields, oil‐soluble AOB (cAOB‐o) was obtained by chemical acylation of AOB‐w with different chain‐length fatty acids varying from C8 to C18. Results indicated that the yield and solubility of cAOB‐o in 1‐octanol solvent depended on the carbon chain length of acyl donor, and cAOB‐o derived from C12 fatty acid exhibited the more powerful antioxidant activity evaluated by β‐carotene/linoleic acid bleaching assay. Total phenolic content decreased by Folin–Ciocalteu assay. Fourier transform infrared spectra showed the increase of a carbonyl (C = O) peak at 1701 cm^?1 and a decrease in the intensity of the absorption at 3400 cm^?1 (O‐H stretching) in cAOB‐o. Acylation was inferred to mainly occur on the hydroxyl groups of flavones C‐glycosides according to the change of high‐performance liquid chromatography spectra and the contents of total flavonoids and phenolic acids. cAOB‐o with the addition of 0.02% significantly increased oxidative stability of palm oil 1.59 times, lard 3.74 times, and fried potato chips 2.08 times, which was better than the effect of oil‐soluble tea polyphenol (P < 0.01). Moreover, cAOB‐o was identified to be actually nontoxicity by an acute oral toxicity test. All the above results indicated that cAOB‐o could be used as a novel and effective oil‐soluble antioxidant in the food industry.     

余甘子核仁油的体外抗氧化活性及其作用机理

本研究旨在研究余甘子核仁油的体外抗氧化作用,并探索多不饱串联和脂肪酸的抗氧化机理。以1,1-二苯基-2-三硝基苯肼(1,1-diphenyl-2-picrylhydrazl,DPPH)自由基与2,2’-联氮-二(3-乙基-苯并噻唑-6-磺酸)二铵盐自由基(2,2’-azinobis-(3-ethylbenzthiazoline-6-sulphoate)radical,ABTS+·)为实验对象,通过余甘子核仁油对2种自由基的清除作用,评估其体外抗氧化能力。结果表明:余甘子核仁油对DPPH自由基清除作用的半抑制浓度(half maximal inhibitory concentration,IC50)为5.08 mg/m L,最大清除率为95.91%;对ABTS+·清除作用的IC50为9.84 mg/m L,最大清除率为98.58%。α-亚麻酸的清除自由基实验表明,余甘子核仁油中起抗氧化作用的主要物质为α-亚麻酸等多不饱和脂肪酸。通过抗氧化前后混合脂肪酸的紫外光谱扫描、红外光谱吸收,检测到了氧化后混合脂肪酸中共轭脂肪酸和羟基脂肪酸的生成,并在DPPH自由基过量条件下,利用气相色谱-质谱联用仪检测到了单羟基脂肪酸的存在,从而证明多不饱和脂肪酸清除自由基反应机理基至少包括多不饱和脂肪酸的共轭化、单分子加成、碳碳双键α-H氧化及环氧化。