Journal of The School of Marine Science and Technology,Vol.4 No.2
Rigor mortis of fish and shellfish and evaluation of freshness of
their muscles as K value
Satomi KOSEKI, Seiichi KITAKAMI, Noboru KATO, and Ken-ichi ARAI
Abstract
To evaluate the freshness of fish and shellfish, the decomposed compounds from ATP in their muscles were
analyzed quantitatively with a lapse of storage time.
The K value of muscle was then demonstrated as B/A×100,where B is the amount of inosine and hypoxanthine
and A is the sum amount of ATP-related compounds.
The onset of rigor mortis and following shortening of the muscles from aqueous animals are known to occur very
earlier than those from terrestrial animals,and the content of ATP is closely related to the changing in development
of rigor mortis of the muscles. Consequently, the method for evaluating the freshness of these muscles by using the
K value has become popular especially in Japan,because the fresh fillet of these animals in rigor state were suitable
to be raw material of ‘Sashimi’and ‘Sushi’.
In addition to the K value, other appropriate evaluating indices like as organoleptical, physical, and microbial
tests depending on the type of processed muscle food product have to measure. The synthetic evaluation by using
several indices used to give us more reasonable evaluation of the quality of product.