Preparation and Characterization of Fish Protein Isolate from Tiger Tooth Croaker (Otholithus ruber) Obtained through PH Shift Method

Development of Fish Protein Isolate (FPI) from tiger tooth croaker (Otholithus ruber) fish meat using the pH shift method was carried out during this study. Tiger tooth croaker was used as raw material because of their abundance and comparatively low price. During the study, the physical characteristics and proximate composition of the fresh fish were analysed. The average length of fish was 19.95 cm and weighed 94.6 g. respectively. FPI treated at different pH treatments (2.5, 4, 7, 11.5 and 12.5) were analyzed for proximate composition, peroxide value and functional characteristics. In the present work, Tiger tooth croaker (Otolithes ruber) fish was found to be suitable for fish protein isolate production using acid or alkali processing and isoelectric precipitation. During storage at ambient temperature for 120 days in a 200 gauge LDPE pouch, Fish Protein Isolates treated at different pH treatments (2.5, 4, 7, 11.5 and 12.5) indicated an increase in moisture content, reduction in protein and lipid content and no significant reduction in ash content. The total protein content was specifically high for pH 7 followed by pH 12.5, 11.5, 4 and 2.5. The effect of different pH on PV of fish protein isolates showed increasing content with increasing storage. The functional properties such as water-holding capacity (WHC), oil-holding capacity (OHC), emulsifying capacity (EC) and foam measurements (Foaming capacity (FC) and foam stability (FS) exhibit high values for all the samples of fish protein isolates. The quality attribute of functional properties of all fish protein isolates samples showed a trend of decreasing during the storage of 120 days.