51A-41

Y. V. A. JANAK KAMIL¹, Y. J. Jeon, and F. Shahidi¹. (1) Department of Biochemistry, Memorial University of Newfoundland, St. John's, NF A1B 3X9, Canada

Seafoods are highly susceptible to quality deterioration and off-flavour development caused by oxidation of their highly unsaturated lipids. Recently, chitosan, a b(1®4) polymer of N-glucosamine, has been identified as a versatile biopolymer for a broad range of food applications. However, fundamental studies on antioxidative effect of chitosan in seafoods are lacking in the literature.

The objective of this study was to evaluate the effect of various concentrations of chitosan from crab shells on lipid oxidation in a cooked fish (herring) model system during refrigerated storage over a 10-day period. For comparative purposes, a number of synthetic antioxidants, including butylated hydroxyanisole (BHA) and butylated hydroxytoluene (BHT) were also employed. Lipid oxidation was assessed using peroxide value (PV), conjugated dienes (CD), 2-thiobarbituric acid-reactive substances (TBARS) and headspace propanal.

Results showed a significant reduction (p£0.05), in lipid oxidation products when 150 and 200 ppm chitosan was used. The PV of 150 and 200 ppm of chitosan treated samples showed no change (p£0.05) after day 2 and all treated samples had lower PV (8-14 meq/kg oil) and CD (5-11) than untreated sample (27 meq/kg oil and 22, respectively). Corresponding TBARS values were 4 and 4.5 times less (22 and 18 mg malonaldehyde equivalents/kg) than those of their untreated counterparts (86 and 82 mg malonaldehyde equivalents/kg, respectively) after 10 days of storage, and were comparable with those of samples treated with 100 ppm of BHA or BHT. Corresponding results for propanal contents of chitosan treated samples were less than half of the untreated sample (190 mg/kg) and reached a plateau on day 6 of storage.

These results suggest that chitosan is effective in controlling lipid oxidation of seafoods and could potentially provide other benefits of commercial importance.