author(s)
SD Meshre, SB Patange, DI Pathan, MM Shirdhankar and SS Sawant

abstract
The pH-shift processing involves the process of solubilization of muscle protein at high alkaline pH (11.0) and low acidic pH (3.0) while precipitation at pH (5.5) of fish muscle. This method of processing was used for the preparation of surimi from the minced obtained from pink perch, Nemipterus japonicus (Bloch, 1791). The study compared biochemical and functional properties of surimi prepared by conventional and pH-shift processing (alkaline and acid) solubilization, along with change in characteristics, if any, during frozen storage. The highest protein recovery rate (%) was obtained in alkaline (76.12%) method, followed by (58%) and conventional method (54.57%). With regard to the proximate composition, highest moisture content was observed in acid surimi, highest protein content in conventional surimi. Lipid and ash content were low in all the surimi samples. The protein solubility and total -SH groups were highest in conventional surimi followed by alkaline-aided and acid-aided surimi. The initial Ca²⁺ ATPase activity of NAM was in the order of conventional > alkaline > acid which decreased during frozen storage. The gel strength of conventional surimi was observed to be 255.56 g.cm which was significantly higher than alkaline-aided and acid-aided surimi which continues to decrease in frozen storage. The whiteness value was also significantly higher in conventional surimi than other two samples. The expressible moisture content has shown decreasing trend during frozen storage. The SDS-PAGE of the sample proteins remains unaffected during frozen storage with molecular weight approx. 210 kDa and the actin with a molecular weight of 45 kDa, however, appearance of myosin heavy chain (MHC) was replaced by light chain (25 kDa) during frozen storage.