Creatine and Creatinine in the Raw and Heated Muscles of Salmon

Abstract

Creatine and creatinine in the 80% ethanol extracts which were the same as employed for the analyses of free amino acids and related compounds in the previous work were estmated. Another muscle extract. 0.25_N perchloric acid extract, was also employed to determine the creatine and creatinine contents. In the ethanol extract, the amounts of creatine ranged 22-38 μmol/g in the raw muscles and 29-37 μmol/g in the heated muscles. After heating the muscles, the creatinine content increased more than 10 μmol/g because of dehydration of creatine and the sum of creatine and creatinine also became considerably higher. The increments of total extractive nitrogen after heating reported previously are explainable by the elevation of extractability of creatine. In the perchloric acid extracts, the concentrations of creatine and creatinine in the raw muscles ranged 38-49 and 0.3-0.7 μmol/g respectively, but no consistent differences in the amounts by sex, species, and parts of muscle were noticed. About one third of creatine was converted to creatinine during heating at 100°C for 40min.