Comparison of proximate and water extractive components in raw mackerel with those in fermented mackerel food Heshiko

摘要

Proximate compostition and several water extractive components in heshiko, a kind of rice-bran-fermented mackerel food, and raw mackerel muscle were determined and compared with each other.Fish muscle was dehydrated to decrease the moisture content markedly, with the permeation of sodium chloride and sugars from the rice-bram mixture. Although partial amounts of lipids eluted from fish bodies, most of them were retained and concentrated in fish muscle owing to the decrease of moisture. As the outflow or the loss of proteins from fish muscle was faster than that of lipids, the protein content in several heshiko samples consequently became lower than that of raw mackerel. Heshiko, on the other hand, contained large amounts of peptides and such free amino acids as Glu, Asp, Gly, Ala, Val, Ile and Leu, suggesting that remarkable proteolysis took place during processing. Organic acids considerably increased in heshiko, whereas nucleotides, which existed abundantly in raw mackerel, decreased to trace levels. Sensory evalution indicates that free amino acids with peptides principally and organic acids supplementally are expected to contribute to the intensive taste of heshiko.