Degradation of Inosine 5′-Monophosphate in the Skeletal Muscle of Several North Atlantic Fishes

Abstract

The rates of breakdown of inosine 5′-monophosphate (IMP) and of its product, inosine (Ino), varied considerably in the muscles of Atlantic cod, haddock, pollock, Atlantic halibut, American plaice, and winter flounder when stored in ice. Haddock and Atlantic halibut were noteworthy in having a very slow rate of breakdown of IMP in relation to the other species. Variations of the rate of dephosphorylation of IMP among individual winter flounder appear to be due to differences in muscle pH. In homogenates of the muscles investigated, the maximum rates of breakdown of IMP occurred in the pH range 8.6–9.4, and were much greater than in the pH range of muscle. The effect of pH on the breakdown of Ino was less pronounced. In haddock and Atlantic halibut there was little or no loss of endogenous IMP when the muscle was cooked at 260 or 100 C; IMP added to Atlantic cod before cooking was also stable.