Title: Effect of Whey Protein Isolate on Ice Recrystallization Characteristics in Whey Protein Isolate/κ-Carrageenan Matrix
Abstract: This study was carried out to investigate the physical and thermal properties of <TEX>${\kappa}$</TEX>-carrageenan (<TEX>${\kappa}$</TEX>-car) gel added whey protein isolate (WPI) as a cryoprotectant. The concentration of <TEX>${\kappa}$</TEX>-carrageenan was fixed at 0.2 wt%. The mean ice crystal size of the WPI/<TEX>${\kappa}$</TEX>-car was decreased according to increasing whey protein isolate concentration. The temperature of gel-sol (Tg-s) and sol-gel (Ts-g) transition of WPI/<TEX>${\kappa}$</TEX>-car maxtrix was represented in the order of 3.0, 0.2, 5.0 and 1.0 wt%. In addition, the transition temperature of gel-sol of WPI in sucrose solution were showed in order of 1.0, 5.0, 0.2 and 3.0 wt% depending on whey protein isolate concentration. The shape of ice crystal was divided largely into two types, round and rectangular form. 1.0 wt% WPI/<TEX>${\kappa}$</TEX>-car matrix at pH 7 and 9 showed minute and rectangular formation of ice crystals and whey protein isolate in sucrose solution at a concentration of 1.0 wt% WPI/<TEX>${\kappa}$</TEX>-car matrix at pH 3 and 5 showed relatively large size and round ice crystals. The ice recrystallization characteristics and cryprotective effect of <TEX>${\kappa}$</TEX>-carrageenan changed through the addition of different concentrations of whey protein isolate. It seems that the conformational changes induced interactions between whey protein isolate and <TEX>${\kappa}$</TEX>-carrageenan affected ice recrystallization.