The development of lactic acid in fish is not only influenced by the degree of muscular exercise in life, but also by the condition of treatment after death. This report deals with theresults conducted by the authors on the determination of lactic acid in fish muscle. The results are shown in Tables 1, 2 and figure 1 and summarized as follows:
(1) The dorsal muscle of bonito,
Katsuwonus vagans, showed the highest value of 1, 170mg. per cent of lactic acid, while the ventral muscle of flat fish,
Xystrias grigorjewi, showed the lowest 34mg. per cent among 14 kinds of fish purchased from the fish shops at Sendai City, Miyagi Prefecture.
(2) The muscle of the fish employed in this experiment is roughly classified into three groups as red, medium red and white muscle fish. The amount of lactic acid was found in the range of 283 to 1, 170 in the red muscles of bonito, tunny, sardine etc., 283 to 639 in the medium red in carp,
Clupanodon punctatus and
Lateolabrax japonicus and 34 to 185mg. per cent in the white in codfish, flatfish etc. These differences are discussed from on ecological point of view.
(3) The lactic acid content in dark muscle is generally lower than that in normal one. This fact is supposed to be due to the difference of the muscular function, namely the dark muscle is not well-developed as well as normal muscle and its function is similar to that of internal organ.
(4) The time to attain the highest concentration of lactic acid in the muscle of carp killed by being stabbed in the medulla of the neck immediately after catching was 55 hours in storage at 0°C and 25 hours at 10°C, while in the case of the fish killed after being left alone and weakened in air at room temperature for 5 hours it was 5 to 15 hours at 0°C and 1 to 5 hours at 10°C.
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