On the production of carbon dioxide in fish flesh during the deterioration of freshness

　魚肉の鮮度と肉中の炭酸ガス(CO2)量との関係を見るために，この実験は行われた.
　サパ(Scomber jatonicus) の精肉を用い，鮮度低下過程中のCO2量をアルカリ吸収逆滴定の方法で実測した結果，発生CO2量は鮮度低下の初期においては急増したが，腐敗期においては漸減した. 従ってCO2量を以てその魚肉の鮮度指標とすることは良法ではないと論じた.
　魚肉中に発生するCO2は，無菌および菌接種試験の結果，その大部分が微生物作用により， 小部分
が筋肉の自己消化作用によるものであることを知った.
　なお，微生物の脱炭酸酵素の至適pHは酸性側にあるとされているが，微アルカリ性の魚肉からも相当量のCO2が発生した.これについて，微生物の脱炭酸酵素は適応酵素であるから， 例えば遊離のアミノ酸などの基質が豊富に存在するならば，微アルカリ性になった魚肉からもCO2は発生しうると推論した.

Carbon dixoide (C02) content in the muscle of the mackerel (Scomber japonicus) during putrefaction was measured.

(1) The quantity of C02 produced and accumulated in the sample of fish muscle increased quick to some degree in process of time, and then gradually decreased after the complete spoilage of the fish muscle. Accordingly, the C02 content of fish muscle might to be of little significance as a better index of the freshness of the fish flesh.

(2) A large amount of C02 was produced by microbial actions, while a little amount of the gas was produced by muscle's autolysis.

(3) Though the optimum pH for decarboxylases are on the acidic side, not a small quantity of CO2 was produced in fish muscle also at an alkaline pH. In this connection, it was discussed that microbial decarboxylases were inducible enzymes, and that they might therefore produce C02 to some extent on the alkaline side if such substrates as free amino acids were present in sufficient amounts, as it was often the case in a putrefying fish flesh.