水産動物肉に関する研究-XXIV

遊離ベタインの定量法

抄録

We have designed a method for the determination of betaine in muscle extractives using ammonium reineckate. This method is based upon the facts that betaine is precipitated with ammonium reineckate at pH 1, and according to Walker & Erlandsen the precipitate (betaine reineckate) is converted with AgNO₃ into betaine nitrate which can be titrated with alkali.
When this method was applied to muscle extractives, certain substances have been proved to interfere the results coprecipitating with betaine by ammonium reineckate and converting with AgN0₃ into acidic salts which could be titrated with alkali as betaine. Recently it was found by C_ROMWELL & R_ENNIE that most of these substances could be effectively removed by treatment with Ag₂O. But we have been unable to remove trimethylaminoxide which gave acidic salt with AgNO₃ by this method. Then this modified method of C_ROMWELL & R_ENNIE was not sufficient to determine betaine in muscle extractives which contained trimethylaminoxide.
Trimethylaminoxide happened to be reduced to trimethylamine which gave no acidic salt, by treating with Cu powder and HCI at 100°C. for 20mins..
We have established the method for the determination of betaine introducing the reducing process. Testing our method for the muscle extractives, we have obtained the 94.7……96.5% of recovery.
The resulting method for determination of betaine is shown as in Fig. 3.