Effects of various salts on IMPase activity and IMP quantity in Coho salmon Oncorhynchus kisutch (Walbaum 1792) Salmonidae

Seki Hiroko, . and Sato Naoko Hamada, . Effects of various salts on IMPase activity and IMP quantity in Coho salmon Oncorhynchus kisutch (Walbaum 1792) Salmonidae. pp. 173-184. ISSN 0116-6514

Coho salmon Oncorhynchus kisutch (Walbaum 1792) Salmonidae is a fast growing species that is reared for food worldwide. After harvest coho salmon is often salted and stored. When a fish dies adenosine triphosphate (ATP) is degraded in the muscles to inosinic acid (IMP) the taste component that gives the fish its flavour. During storage IMP is degraded to non-taste components by the IMP-degrading enzyme (IMPase) resulting in a loss of flavour. Therefore it is crucial to suppress IMPase activity in order to maintain IMP levels. In this study IMPase activity was investigated at various pH levels and with salts used for storage of coho salmon along with the resulting amount of IMP and changes in pH level. The results showed that the amount of IMP significantly decreased from 9.5 molg-1 on day 0to 4.6 molg-1on day 4(p0.05) in fish stored at 4oC in our laboratory but the pH level remained constant at 6.10.1. The enzyme activity was the highest at pH 6 and decreased sharply at pH 7-8. The salts that effectively maintained IMP in coho salmon were in the following order MgSO4 and Na2SO4 at pH 4-5; MgCl2 CaCl2 MgSO4 and Na2SO4 at pH 6; and NaCl CaCl2 and Na2SO4 at pH 7-8. These results indicated that the amount of IMP present after several days of storage was significantly higher with the addition of these salts.

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Abstract

Coho salmon Oncorhynchus kisutch (Walbaum 1792) Salmonidae is a fast growing species that is reared for food worldwide. After harvest coho salmon is often salted and stored. When a fish dies adenosine triphosphate (ATP) is degraded in the muscles to inosinic acid (IMP) the taste component that gives the fish its flavour. During storage IMP is degraded to non-taste components by the IMP-degrading enzyme (IMPase) resulting in a loss of flavour. Therefore it is crucial to suppress IMPase activity in order to maintain IMP levels. In this study IMPase activity was investigated at various pH levels and with salts used for storage of coho salmon along with the resulting amount of IMP and changes in pH level. The results showed that the amount of IMP significantly decreased from 9.5 molg-1 on day 0to 4.6 molg-1on day 4(p0.05) in fish stored at 4oC in our laboratory but the pH level remained constant at 6.10.1. The enzyme activity was the highest at pH 6 and decreased sharply at pH 7-8. The salts that effectively maintained IMP in coho salmon were in the following order MgSO4 and Na2SO4 at pH 4-5; MgCl2 CaCl2 MgSO4 and Na2SO4 at pH 6; and NaCl CaCl2 and Na2SO4 at pH 7-8. These results indicated that the amount of IMP present after several days of storage was significantly higher with the addition of these salts.

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Item Type:	Article
AGROVOC Term:	Oncorhynchus kisutch
AGROVOC Term:	Coho salmon
AGROVOC Term:	Salts
AGROVOC Term:	Salmonidae
AGROVOC Term:	Adenosine triphosphate
AGROVOC Term:	Flavour
AGROVOC Term:	food storage
AGROVOC Term:	Salting
AGROVOC Term:	Enzymatic activity
AGROVOC Term:	Centrifugation
Depositing User:	Ms. Suzila Mohamad Kasim
Last Modified:	24 Apr 2025 06:28
URI:	http://webagris.upm.edu.my/id/eprint/23662

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