Fluorescence of fish muscle: Description and measurement of changes occurring during frozen storage

Changes were observed in the fluorescence of skeletal muscle of many species of fish during storage in the frozen state. As intrinsic pyridine nucleotide fluorescence associated with degree of freshness, faded, two other visible fluorochromes developed. Production of the latter was favoured by minimal pre‐freezing delays, protection from air, low pH and high cold‐store temperatures. The results suggest that careful visual examination of fish muscle fluorescence, before and after thawing, could be useful in the assessment of cold storage history.