Abstract
In order to see if the ratio of steam distillation of volatile acids is feasible in determining freshness of fish meat, a series of test have been carried out using the samples taken from the bonito, Euthynnus Yaito KISHINOUYE. Fresh meat sampled out of the parts such as the dorsal, caudal, ventral, and the dark muscle of a carcass, was separately comminuted. The spoiled samples were prepared from the similar parts of another fish which had been left under natural condition for three days. The ratios obtained from steam distillation of the samples were compared with the values of pH and volatile basic nitrogen (abbrev. V-N) measured for each sample.
As obvious from the results shown in Tables 1 and 2 quality of the fresh samples tested with V-N or pH hardly revealed differences among the anatomical parts. However, when expressed in the ratio of second distllation, the fresh samples had different values in accordance with the parts as:100 for dorsal, 93 for caudal, 82 for ventral, and 74 for dark muscle.
Spoilage measured with V-N and pH of the deteriorated samples was fairly distinct between the parts. The second distillation ratios of the samples were 75 for dorsal, 75 for caual, 59 ventral, and 56 for dark muscle. Neglecting individual variance between the two specimens, the spoilage of the samples caused by three days' standing may be expressed as 75% for dorsal, 81% for caudal, 72% for ventral, and 75% for dark muscle. The greatest spoilage took place in the ventral muscle.
On the basis of the above experiments it may be said that freshness of two fish belonging to the same species can be examined by comparing the distillation ratios obtained from the similar parts of them, although quality of a round fish cannot be determined from the ratio of its parts.
