Gamma irradiation on moisture migration and lipid degradation of Micropterus salmoides meat

Abstract

To investigate the effect of gamma (γ) irradiation on the water migration and lipid degradation of Micropterus salmoides (MS), the MS meat were cold-air dried for 0, 2, 4, 6, 8 and 10 h, treated by γ ray from the Cobalt 60 at a dose of 3.36 kGy, then stored for 21 days. The low-field nuclear magnetic resonance (LF-NMR) results showed that the fresh MS meat contained immobile water at 86.33–89.80%. After drying and irradiation, the single amplitude and transverse ( T 2 ) relaxation times of the immobilized water decreased. During the storage, the MS meat in irradiation group can keep quality for 21 days, and T 21 showed no changes during the whole period. At the results of irradiation on lipid degradation, the acid value (AV) shows drying-time dependent decrease, while the peroxide value (PV) changes conversely. Lower malondialdehyde (MDA) content was found in the MS meat dried for 4–6 h than the cases of other groups ( p ＜0.05). After irradiation, ten fatty acids were detected in fresh MS meat and lower loss of fatty acid types were found in the MS meat dried for 4 h. Among these fatty acids, palmitic acid (C16:0) and oleic acid (C18:1) exhibited higher proportion at 18.33%–25.66% and 36.6%–51.28%, respectively. In the work, the MS meat dried for 4 h, containing about 37% water, is more tolerant to γ irradiation than the fresh or the over-drying MS meat. • Gamma irradiation will further reduce the water content in dried bass flesh. • Irradiation increase the binding force of dried bass muscle to residual water. • Dried bass flesh is more resistant to gamma irradiation than fresh bass flesh. • Excessive or low water content can increase the lipid oxidation in bass flesh.