Udaya N. Wanasundara

Antioxidant and pro-oxidant activity of green tea extracts in marine oils

The activity of green tea extracts (GTE) on the oxidation of refined, bleached and deodorized (RBD) seal blubber oil (SBO) and menhaden oil (MHO) was examined under Schaal oven conditions at 65 °C. Progression of oxidation was monitored using weight gain, peroxide value (PV) and 2-thiobarbituric acid-reactive substances (TBARS) data. GTE exhibited a pro-oxidant effect in both oils examined, perhaps due to the catalytic effect of their chlorophyll constituents. Therefore, in follow-up experiments, a column chromatographic technique was employed to remove chlorophyll from GTE. The resultant dechlorophyllized green tea extract (DGTE) was applied to both SBO and MHO at 100, 200, 500 and 1000 ppm levels. The antioxidant activity of DGTE was compared with the effects of the commonly-used antioxidants such as butylated hydroxyanisole (BHA), butylated hydroxytoluene (BHT) and tert-butylhydroquinone (TBHQ) at 200 ppm and α-tocopherol at 500 ppm. DGTE at ≥200 ppm exhibited excellent antioxidant activity in both oils and its efficacy was higher than that of BHA, BHT and α-tocopherol, but less than that of TBHQ.

Omega-3 fatty acid concentrates: nutritional aspects and production technologies

Abstract Production of omega-3 (ω3) fatty acid concentrates continues to be a topic of interest for both the pharmaceutical and health food industries. Since the early studies on long-chain ω3-polyunsaturated fatty acids (PUFA) in 1929 by Burr and Burr (J. Biol. Chem., 1929, 82, 345–367), the health benefits of consumption of this class of compounds have been thoroughly investigated. With the growing public awareness of the nutritional benefits of seafoods and their ω3-PUFA, the market for such products is expected to grow in the future. This overview provides a discussion of nutritional aspects and methodologies used for producing ω3 concentrates from source materials.

Concentration of omega 3-polyunsaturated fatty acids of seal blubber oil by urea complexation: optimization of reaction conditions

Abstract Production of omega-3 fatty acid concentrates from seal blubber oil (SBO) was optimized. In this process, the content of total ω3-fatty acids, Y1; eicosapentaenoic acid (EPA), Y2; and docosahexaenoic acid (DHA), Y3 in the final product was maximized. A three-factor central composite rotatable design (CCRD) was used to study the effect of urea-to-fatty acid ratio (X1), crystallization time (X2), and crystallization temperature (X3). Second-order polynomial regression models for Y1, Y2 and Y3 were employed to generate response surfaces. Under optimum conditions the maximum amount of total ω3 fatty acids (88.2%) from SBO was obtained at a urea-to-fatty acid ratio of 4.5, a crystallization time of 24 h, and a crystallization temperature of −10°C. ©

Canola extract as an alternative natural antioxidant for canola oil

The antioxidative activity of ethanolic extracts of canola meal at 100, 200, 500 and 1000 ppm on refined-bleached (RB) canola oil was examined and compared with commonly used synthetic antioxidants, such as butylated hydroxyanisole (BHA), butylated hydroxytoluene (BHT), BHA/BHT/monoglyceride citrate (MGC) andtert-butyl-hydroquinone (TBHQ). Stability of RB oil was monitored under Schaal oven test conditions at 65°C over a 17-d period. Progression of oxidation was monitored by weight gain, peroxide, conjugated diene, 2-thiobarbituric acid and total oxidation values. Canola extracts at 500 and 1000 ppm were more active than BHA, BHT and BHA/BHT/MGC and less effective than TBHQ at a level of 200 ppm.

Natural antioxidants from low-pungency mustard flour

Abstract The ethanolic extracts of low-pungency mustard flour were separated on a Sephadex LH-20 column. Three major fractions were separated according to the UV absorbance readings at 280 nm. Antioxidant activity of these fractions was evaluated in a β-carotene-linoleate model system. Fraction I was most effective and showed absorbance readings similar to those of sinapic acid, p-hydroxybenzoic acid and trihydroxy phenolic compounds such as flavones or flavanones. Fraction II exhibited moderate antioxidant activity and showed the possible presence of phenolic acids and trihydroxy compounds. Fraction III was least effective and did not contain any trihydroxy compounds as indicated by a thin layer chromatography spray method.

Stabilization of seal blubber and menhaden oils with green tea catechins

Catechins, namely (−)epicatechin (EC), (−)epigallocatechin (EGC), (−)epicatechin gallate (ECG) and (−)epigallocatechin gallate (EGCG), were isolated from commercial Chinese green leaves. The antioxidant activity of isolated catechins was compared with those of α-tocopherol, butylated hydroxyanisole (BHA), butylated hydroxytolene (BHT) andtert-butylhydroquinone (TBHQ), all at 200 ppm, in refined, bleached and deodorized seal blubber oil and menhaden oil. The study was carried out under Schaal oven test conditions at 65°C over a 144-h period, except for weight gain measurements, which were continued for up to 200 h. Progression of oxidation was monitored by measuring changes in weight gain and values of peroxide, conjugated diene, and 2-thiobarbituric acid-reactive substances. Oils treated with tea catechins showed excellent oxidative stability as compared with samples that contained commonly used antioxidants, such as α-tocopherol, BHA, BHT, and TBHQ. The potency of catechins in prevention of oxidation of marine oils was in the decreasing order of ECG> EGCG> EGC> EC; ECG was slightly more effective than TBHQ in systems studied.

Comparison of standard and NMR methodologies for assessment of oxidative stability of canola and soybean oils

The oxidative stability of refined, bleached and deodorized canola and soybean oils was evaluated over a 30-day dark storage period at 65 °C. Peroxide value (PV), conjugated diene (CD) and triene (CT) contents, 2-thiobarbituric acid reactive substances (TBARS) and p-anisidine values were determined. In addition, NMR spectroscopy was used to monitor relative changes in the proton absorption pattern of the fatty acids of oils during storage. Canola oil showed higher PV, CD, CT and TBARS as compared with those for soybean oil. The ratio of aliphatic to olefinic protons in both oils, determined by NMR spectroscopy, increased steadily over the entire length of the storage period, indicating progressive oxidation of unsaturated fatty acids in both oils.

Stabilization of canola oil with flavonoids

Abstract The antioxidant activity of a number of flavonoids in refined-bleached (RB) canola (double-zero rapeseed) oil is compared with that of commonly used synthetic antioxidants, namely, butylated hydroxyanisole, BHA, and butylated hydroxytoluene, BHT. The study was carried out over a thirteen-day period at 65°C and progression of oxidation was followed by monitoring weight gain and peroxide and 2-thiobarbituric acid (TBA) values. Among the flavonoids tested, myricetin, (−)epicatechin, naringin, rutin, morin, and quercetin were superior to BHA and BHT in inhibiting oil oxidation. The addition of myricetin, the most active flavonoid tested, delayed the induction period of lipid oxidation by up to fifteen days and also inhibited the formation of oxidation products by 69% during this period. Natural flavonoids may therefore have potential application for the stabilization of canola oil.

Partial characterization of natural antioxidants in canola meal

Abstract Defatted canola meal was extracted with 95% ( v v ) ethanol at 80 °C. The extract was fractionated on a Sephadex LH-20 column using methanol as eluate. Seven major fractions were isolated according to UV absorption, content of phenolics and sugars. Antioxidant activity of these fractions was evaluated in a β-carotenelinoleate model system. Fraction IV showed the best antioxidant effect by exhibiting the highest preventive activity against the bleaching of β-carotene. Further separation of this fraction on TLC indicated that it contains several compounds including phenolic acids and trihydroxy phenolic compounds such as flavones and flavonols.

Effect of natural antioxidants on the stability of canola oil

Abstract Stabilization of canola oil with extracts of canola meal at 100, 200, 500 and 1000 ppm and commercially-available flavonoids (apigenin, chrysin, quercetin, myricetin, morin, kaempferol, rutin, naringenin, naringin, taxifolin and [-]epicatechin) at 200 ppm level was examined. Commonly used synthetic antioxidants such as butylated hydroxyanisole (BHA), butylated hydroxytoluene (BHT) at 200 ppm and BHA/BHT/monoglyceride citrate (MGC) at 250 ppm were used as the control additives. Weight gain, peroxide, TOTOX and 2-thiobarbituric acid reactive substances (TBARS) values as well as a novel NMR methodology were used for monitoring oxidative stability of the oil. Among the additives tested, canola extracts at 500 and 1000 ppm and myricetin, (-)epicatechin, naringin, rutin, morin and quercetin were more effective than BHA and BHT. Therefore, canola extract and some of the flavonoids occurring in natural food ingredients may provide an opportunity for their application in canola and other vegetable oils.