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¹ Ubon Ratchathani Rajabhat University, Program in Food Science and Technology, Faculty of Agriculture, Ubon Ratchathani, 34000, Thailand
² Prince of Songkla University, Department of Food Technology, Faculty of Agro-Industry, Hat Yai, Songkhla, 90112, Thailand
³ Maejo University, Faculty of Engineering and Agro-Industry, Sansai, Chiangmai 50290, Thailand DOI : 10.4194/1303-2712-v19_11_06 Viewed : 3267 - Downloaded : 2663 Effects of different iron concentrations (0, 5, 10, 15, 20 and 25 ppm) on the lipid oxidation, color and protein changes of Sawai (Pangasianodon hypophthalmus) pastes subjected to multiple freeze-thaw cycles, were investigated. TBARS value of all samples increased as the number of freeze-thaw cycle increased (P<0.05). The increase in TBARS values of Sawai pastes induced by iron was in a dose dependent manner. Increasing in lipid oxidation of the samples containing iron was concomitant with the increase in b*-value (yellowness). The changes in protein oxidations and protein solubility were more pronounced when freeze-thaw cycles increased. However, iron at all concentrations showed negligible effects on those changes. Decreasing in Ca2+- ATPase activity of fish natural actomyosin was found in all samples with increasing freeze-thawing process. SDS-PAGE showed that proteins with high MW were observed in the sample with added iron. Therefore, iron induced the yellow discoloration in Sawai muscle, associated with lipid oxidation, particularly with multiple freeze-thaw cycles. Keywords : Freeze-thaw cycles, Pangasianodon hypophthalmus, Iron, Sawai, Actomyosin