Differential role of endogenous cathepsin and microorganism in texture softening of ice-stored grass carp (Ctenopharyngodon idella) fillets.
BACKGROUND
Texture deterioration often negatively affects sensory attributes and commercial values of ice-stored fish fillets. The mechanism of softening of fish fillets during chilling storage is not fully resolved. Grass carp is a predominant freshwater fish species in China. The objective of the present study was to investigate the differential role of endogenous cathepsin and microorganisms in texture softening of ice-stored grass carp fillets.


RESULTS
The fillets were immersed in either NaN3 solution to reduce microbial activity or in iodoacetic acid solution to exclude cathepsin activity before ice storage. Treatment with NaN3 reduced microbial load of fillets below 2 log CFU g(-1) muscle during the entire storage period, and had no significant influence on the cathepsin activity and proteolysis. But the shear force of fillets treated with NaN3 decreased by 66% after 21 days of storage. Meanwhile, treatment with iodoacetic acid inactivated cathepsin B and B + L but did not significantly affect the microbial growth of fillets. Compared to NaN3 treatment, iodoacetic acid effectively alleviated softening and inhibited the increase in TCA-soluble peptides during storage.


CONCLUSIONS
This study demonstrated that proteolysis induced by endogenous cathepsins, rather than microorganisms, plays an important role in texture softening of ice-stored grass carp fillets. © 2015 Society of Chemical Industry.
State Key Laboratory of Food Science and Technology, School of Food Science and Technology, Jiangnan University, Wuxi, Jiangsu, 214122, People's Republic of China.
Lihong
L
Ge
State Key Laboratory of Food Science and Technology, School of Food Science and Technology, Jiangnan University, Wuxi, Jiangsu, 214122, People's Republic of China.
Yanshun
Y
Xu
State Key Laboratory of Food Science and Technology, School of Food Science and Technology, Jiangnan University, Wuxi, Jiangsu, 214122, People's Republic of China.
Wenshui
W
Xia
State Key Laboratory of Food Science and Technology, School of Food Science and Technology, Jiangnan University, Wuxi, Jiangsu, 214122, People's Republic of China.
Qixing
Q
Jiang
State Key Laboratory of Food Science and Technology, School of Food Science and Technology, Jiangnan University, Wuxi, Jiangsu, 214122, People's Republic of China.
Xiaoqing
X
Jiang
D000818:Animals; D001419:Bacteria / Q000187:drug effects; D002347:Carps / Q000382:microbiology*; D002401:Cathepsin B / Q000378:metabolism; D002402:Cathepsin D / Q000378:metabolism / Q000502:physiology; D056668:Cathepsin L / Q000378:metabolism / Q000494:pharmacology; D002403:Cathepsins / Q000378:metabolism* / Q000502:physiology*; D002681:China; D003080:Cold Temperature; D029941:Fish Proteins / Q000378:metabolism; D005519:Food Preservation / Q000379:methods*; D061353:Food Storage; D007053:Ice; D019807:Iodoacetic Acid / Q000494:pharmacology; D059748:Proteolysis; D017747:Seafood; D019810:Sodium Azide / Q000494:pharmacology
D029941:Fish Proteins; D007053:Ice; D019810:Sodium Azide; D002403:Cathepsins; D002401:Cathepsin B; D056668:Cathepsin L; D002402:Cathepsin D; D019807:Iodoacetic Acid
cathepsin activity; grass carp fillets; ice storage; microorganism; softening; texture