食品の鮮度測定法に関する研究(3)-魚肉の揮発性塩基の水蒸気蒸溜による一新定量法-

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A new steam-distilling method has been presented for the determination of the volatile base-N in fish flesh. Data have been presented showing that the fish muscle brei on direct steam distillation at either pH 7.6 or 9.0 gave value of about 145% of that obtained by the vacuum method, whereas a 1-3% trichloracetic acid extract of the brei gave value of nearly the same as that by the vecuum method, irrespectively of the freshness of the sample used. The procedure for the determination is as follows: To a 16-g. portion flesh brei are added 100cc. water intimately mixing. Then 50cc. of 7% trichloracetic acid are gradually added with a constant stirring, followed by the filtration with a dry filter paper. The filtrate is subject to the steam distillation using the apparatus shown in Fig. 1. Firstly, 5cc. of n/14 H2SO4 are taken in the distillate-receiving tube, E, Which is connected to the cooler, C, as shown in Fig. 1. Then, a 50-cc. portion of the filtrate is poured into the inner tube of the apparatus, D, and 10cc. of 10% potassium carbonate are added. Next, the steam is passed into the inner tube by way of the steam jacket. when the distillate amounts to 40cc., the receiving tube is disconnected. The sample remained in the inner tube of the apparatus, D, is drawn out into the outer jacket by clamping both c2 and c3. Through the receiving tube carbon dioxide-free air is passed for longer than three minutes. An excess acid remained is titrated with n/28 NaOH using methyl red as indicator. The mg.%-value for volatile base-N can becalculated by equation (1) or approximate equation (2). The above procedure enables us to reduce the time required for one determination to about one-fourth of that required for the vacuum-distilling procedure.
社団法人日本水産学会の論文

食品の鮮度測定法に関する研究(3)-魚肉の揮発性塩基の水蒸気蒸溜による一新定量法-

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