Endogenous proteases in giant freshwater prawn ( <i>Macrobrachium rosenbergii</i> ): changes and its impacts on texture deterioration during frozen storage
Qixing Jiang, Pei Gao, Jiatong Liu, Dawei Yu, Yanshun Xu, Fang Yang, Bin Wang, Peipei Yu, Wenshui Xia
Abstract
Summary Effects of endogenous enzymes on texture deterioration of Macrobrachium rosenbergii during frozen storage (−18 °C) were investigated. The prawn was pretreated with iodoacetic acid (IAA) solution to inhibit cysteine proteases and/or phenylmethylsulfonyl fluoride (PMSF) solution to inhibit trypsin before frozen storage, and sterile distilled water was used as the control. After 16 weeks of cryopreservation, the shear force of the groups treated with enzyme inhibitors was significantly higher than that of sterile distilled water‐treated group (control; P < 0.05), while significantly fewer TCA‐dissolved peptides, α‐amino nitrogen and Myofibril fragmentation index (MFI) value were observed in all inhibitor‐treated groups ( P < 0.05). Compared with PMSF treatment, IAA or IAA + PMSF treatment effectively alleviated softening and remarkably reduced the accumulation of TCA‐soluble peptides and AAN (α‐amino nitrogen) during frozen storage, with a lower MFI value and a higher sodium dodecyl sulphate‐polyacrylamide gel electrophoresis band intensity. Therefore, endogenous cysteine proteases in muscle play a crucial part in texture deterioration of giant freshwater prawn during cryopreservation.