Maximum Rates of Glycolysis and Breakdown of High-Energy Phosphorus Compounds in Prerigor Cod Muscle at Specific Freezing Temperatures Between −1 and −4 C

The rates of glycolysis and of breakdown of high-energy phosphorus compounds in prerigor muscle have been investigated at specific temperatures in the critical freezing range between −1 and −4 C to determine the temperature at which maximum degradation occurs. Glycolytic activity increased with decreasing temperature below −1 C, reaching a maximum rate with a broad peak between −2.5 and −3.2 C, then slowing down as the temperature dropped to −4 C. The maximum rate of breakdown of high-energy phosphorus compounds also occurred around −3 C. Loss of Δ7P was most rapid between −2.6 and −3 C with an average velocity of 3.5 μg atoms P/g per hour. From 25 to 41% of the initial Δ7P content was derived from creatine phosphate and this fraction was usually depleted within the first 2 h of frozen storage. Deamination of adenine nucleotides to inosine nucleotide compounds was faster at −3 C than at −2 or −4 C.