POSTMORTEM TENDERIZATION OF RAINBOW-TROUT (ONCORHYNCHUS-MYKISS) MUSCLE CAUSED BY GRADUAL DISINTEGRATION OF THE EXTRACELLULAR-MATRIX STRUCTURE

A histological study combined with a newly devised compression test was carried out to clarify the mechanism of the post-mortem tenderisation of rainbow trout (Oncorhyncus mykiss Walbaum) muscle. It is suggested that the integrity of the extracellular matrix structure is very important for the toughness of fish muscle. During chilled storage, the gradual disintegration of the extracellular matrix structure was clearly demonstrated by light microscopic observations after compression but little change was observed without it. It is therefore suggested that the post-mortem tenderisation of fish muscle is closely related to the gradual disintegration of the extracellular matrix structure after death.