Glycolysis and ATP degradation in cod ( Gadus morhua ) at subzero temperatures in relation to thaw rigor

Glycolysis was shown to occur during freezing of cod of decrease in glycogen and an increase in lactate. In addition, the ATP content decreased during freezing. Synthesis of ATP was measured as degradation of glycogen. During storage at -9 and - 12 degreesC it was found that degradation of ATP was faster than synthesis of ATP. This was leading to presence of glycogen even at low ATP concentrations. The ATP and glycogen degradation rates and lactate formation rate reached an optimum (both in small samples as well as in whole fish) when stored at -9 degreesC compared to -12 degreesC. Evidence of ATP synthesis at 0 degreesC during thawing was obtained in samples as well as in whole fish. Reduction or elimination of thaw rigor effects (shrinkage and drip loss) during a period of frozen storage were examined. When thawing at 5 degreesC, fillets stored at -9 degreesC showed significantly less shrinkage than fillets stored at -40 degreesC. In addition, pre-rigor fillets (-40 degreesC) showed significantly the smallest drip loss compared with fillets stored at -9 degreesC. (C) 2001 Academic Press.