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Linoleic Acid System (linoleic + acid_system)
Selected AbstractsEffect of different cooking methods on the antioxidant activity of some vegetables from PakistanINTERNATIONAL JOURNAL OF FOOD SCIENCE & TECHNOLOGY, Issue 3 2008Bushra Sultana Summary The effects of different cooking methods (boiling, frying and microwave cooking) on the antioxidant activity of some selected vegetables (peas, carrot, spinach, cabbage, cauliflower, yellow turnip and white turnip) were assessed by measuring the total phenolic contents (TPC), reducing power and percentage inhibition in linoleic acid system. TPC (gallic acid equivalents g/100 g of dry weight) and reducing power of the methanolic extracts of raw-, microwaved-, boiled- and fried vegetables ranged 0.333,2.97, 0.52,2.68, 0.48,2.08, 1.00,2.02 and 0.391,2.24, 0.822,1.10, 0.547,1.16, 0.910,4.07, respectively. The level of inhibition of peroxidation ranged 71.4,89.0, 66.4,87.3, 73.2,89.2 and 77.4,91.3%, respectively. Antioxidant activity of the vegetables examined was appreciably affected because of varying cooking treatments. TPC of vegetables, generally, decreased by boiling, frying and microwave cooking. There was a significant (P < 0.05) increase in reducing power as a result of frying. However, boiling and microwave cooking did not affect reducing power. Inhibition of peroxidation increased by boiling and frying, whereas, in contrast it was decreased by microwave cooking. The results of the present investigation showed that all the cooking methods affected the antioxidant properties of the vegetables; however, microwave treatment exhibited more deleterious effects when compared with those of other treatments. Thus an appropriate method might be sought for the processing of such vegetables to retain their antioxidant components at maximum level. [source] Establishment of a quantitative structure,activity relationship model for evaluating and predicting the protective potentials of phenolic antioxidants on lipid peroxidationJOURNAL OF PHARMACEUTICAL SCIENCES, Issue 3 2003Zhiyong Cheng Abstract Antioxidant activities of phenolic compounds have been extensively explored, but the determinant factors underlying their mechanisms of action remain to be elucidated. In the present work, a series of phenolic compounds (hydroxylated connamic, benzoic acid, and polyphenol) were studied for their protection against lipid peroxidation (LPO) in two model experiments, pre-emulsified linoleic acid system and phosphate buffered linolenic acid system. The mechanisms of action as well as activity determinants were investigated by computational chemistry and multiple-linear regression analysis. Upon elucidating the LPO inhibition properties and the relationship between their structural natures and antioxidant activities (SAR), a fairly satisfactory multidescriptor quantitative SAR model was derived, which extended our understanding of LPO inhibition mechanisms and should be valuable in assessing or predicting the anti-LPO activity of phenolic antioxidants. © 2003 Wiley-Liss, Inc. and the American Pharmaceutical Association J Pharm Sci 92:475,484, 2003 [source] Antioxidant activity of hydrolysates derived from porcine plasmaJOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE, Issue 11 2009Xueming Xu Abstract BACKGROUND: In China alone, more than 400 million pigs are slaughtered each year to provide meat. Porcine blood is rich in proteins but is usually discarded, which can cause environmental contamination. Recovering porcine blood and converting it to high-value products is therefore economically and environmentally desirable. However, very little information on antioxidant peptides from porcine blood by-products is currently available. In this study the antioxidant properties of porcine plasma hydrolysates PPE and PPA prepared with pepsin and papain respectively were investigated. RESULTS: Both PPE and PPA showed excellent antioxidant activity in a linoleic acid system (AL) compared with ,-tocopherol (VE) at the same concentration (P < 0.01). Their activities were respectively 3.33 and 1.83 times stronger than that of VE at a concentration of 10 µg mL,1 and 5.4 and 5.6 times stronger at 100 µg mL,1. The 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical-scavenging activity (DRSA) reached 48.4 and 43.1% for PPE and PPA respectively at 500 µg mL,1. The ferrous ion-chelating power (FICP) of PPE at 100 µg mL,1 was about 1.5 times stronger than that of 10 µmol L,1 ethylene diamine tetraacetic acid (EDTA) in a 50 µmol L,1 Fe2+ system, whereas the FICP of PPA at 100 µg mL,1 was 61% that of 10 µmol L,1 EDTA. Furthermore, PPE was separated on Resource 15RPC and Superdex peptide 10/300GL columns, and the antioxidant activity of the peptides and its relationship to their polarity and molecular weight (MW) were analysed. The hydrolysate was divided into four groups (R1,R4) with hydrophobicities ranging from weak to strong by Resource 15RPC, while it was divided into three groups (S1, MW 7,12 kDa; S2, MW 3,7 kDa; S3, MW 1,3 kDa) by Superdex peptide 10/300GL. CONCLUSION: The results showed that AL was significantly and positively correlated with the relative amounts of R1, S2 and S3 and that DRSA was dependent on R3 and S1. The fractions of PPE were not responsible for FICP. Copyright © 2009 Society of Chemical Industry [source] Evaluation of heat and oxidative damage during storage of processed tomato products.JOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE, Issue 9 2003Abstract Tomato products (pulp, puree and paste) submitted to accelerated aging (30, 40 and 50 °C for 3 months) were studied to evaluate variations in the kinetics of the degradation of antioxidants and antioxidant activity. The carotenoids lycopene and ,-carotene, ascorbic acid, rutin and total phenolics were analysed. The antioxidant activity was measured using (a) the xanthine oxidase (XOD)/xanthine system, which generates superoxide radicals and hydrogen peroxide, and (b) the linoleic acid/CuSO4 system, which promotes lipid peroxidation. The ascorbic acid content decreased even at 30 °C, following pseudo-first-order kinetics, with an activation energy of 105 200 J mol,1 for tomato pulp and 23 600 J mol,1 for tomato paste. The lower the initial ascorbic acid content, the higher was the degradation rate. Variations in phenolic compounds occurred at 40 °C and higher, following pseudo-zero order kinetics. The antioxidant activity of the hydrophilic fraction of the tomato products depended on both antioxidant degradation and the Maillard reaction and could not be described by a kinetic model. The ,-carotene content decreased even at 30 °C, whereas the lycopene content was stable in all samples. The antioxidant activity of the lipophilic fraction of the tomato products decreased following pseudo-first order kinetics, with an activation energy of 22 200 J mol,1 for tomato pulp and 20 200 J mol,1 for tomato paste. It is concluded that significant ,oxidative damage' can occur in tomato products during their commercial shelf-life. Copyright © 2003 Society of Chemical Industry [source] | ||||||||||