Effect of varying levels of heat and formaldehyde treatment of sardine fishmeal on nitrogen solubility, in vitro ammonia release and protein fractions

Abstract

The study was conducted to determine the effect of different levels of heat and formaldehyde treatment on nitrogen solubility, in vitro ammonia release and protein fractions of sardine fish meal. Heat treatment of sardine fish meal was carried out at 110, 120, 130, 140 and 150°C for 30, 60 and 120 min. A significantly lowest nitrogen solubility was observed at 150°C for 120 min in all the 4 solvents tested. A significantly lowest ammonia concentration was observed in heat treated sardine fish meal at 150°C at 120 min. A significantly higher B2 + B3 – C (undegrdable but digestible protein) was obtained at 130°C for 120 min and there was no significant increase beyond this temperature and time. Formaldehyde treatment was examined at 0.5, 1.0, 1.5 and 2.0 g formaldehyde per 100 g crude protein. The nitrogen solubility and in vitro ammonia concentration was reduced significantly at 1% formaldehyde treatment. Sardine fish meal protein fractions A, B1, B2 and B3 showed significant change at 1% formaldehyde treatment. On a holistic view it could be considered that heat treatment at 130°C for 120 min and formaldehyde treatment at 1% level were optimal for protection sardine fish meal protein.