Autolysis of clown featherback (Chitala ornata) muscle

Abstract

© 2014 Chiang Mai University. Clown featherback (Chitala ornata) is a freshwater fish important in the cuisine of Thailand and other Southeast Asian countries. It has a short marketable life due mainly to poor gelling characteristic even when stored in ice. This deterioration has been associated with muscle autolysis. The research was aimed to investigate the autolysis of clown featherback muscle (CFM). To test autolysis, mince from CFM was incubated in a temperature controlled water bath for 60 min at 5, 10, 20, 30, 40, 50, 60, 65, 70, 75 or 80 °C at pH levels over the range of 2-11. The results showed that the highest autolytic activity was at 70 °C and it occurred at pH levels of 4 and 7, with pH 4 showing the highest autolysis. CFM was incubated with its crude enzyme counterpart at the physiological pH (6.73) at both 4 °C and 25 °C. Degradation of natural actomyosin showed that after incubation at either temperature myosin heavy chain was susceptible to hydrolysis indicating that autolysis of CFM took place even at low temperature as affected by its endogenous proteases. The effects of several protease inhibitors were tested and autolysis at the physiological pH (6.73) was strongly inhibited by 10 μM pepstatin A (20.3% inhibition), which had significantly higher inhibitory activity (P < 0.05) among the protease inhibitors tested. This suggests that aspartic protease was the major proteinase in CFM.