Effect of protamine and chitosan mixture on fresh preservation of Ctenopharyngodon idellus

In order to investigate the feasibility of protamine-chitosan composite preservative on storage of Ctenopharyngodon idellus,the grass carp fillets were processed by 3 different composite ratios and stored at 4 ℃. Indexes including Total viable counts(TVC),Total volatile base nitrogen(TVB-N),drip loss,pH,freshness index K value and sensory evaluation value were evaluated to reflect the changes of fish quality. The results showed that the composite treatment groups(CP1,CP2,CP3)had distinctly higher sensory scores than the control group(CK)during storage,while as with pH,no obvious difference was observed.The variation trend of sensory evaluation showed a highly significant correlation with tendency variation of TVC,TVB-N,drip loss and K value(p<0.01),the correlation coefficient r lying in -0.887~-0.991.The results indicated that protamine-chitosan composite preservative could better maintain the quality of grass carp during storage time and prolong its shelf life.Above all,the CP2 treatment group(1%+0.5% chitosan protamine solution)possessed the best fresh-keeping effect,which could be preserved for 10 days with each index beingin the acceptable range,extending the shelf life for more than 4 days compared with the control group.