ASSAY OF VITAMIN B_(12) ACTIVITY IN FERMENTED SOYBEAN PRODUCTS WITH E.COLI MUTANT
- VernacularTitle:用大肠桿菌测定豆类发酵食品中维生素B_12的活性
- Author:
Hsuching WANG
;
Chihping SHEN
- Publication Type:Journal Article
- From:
Acta Nutrimenta Sinica
1956;0(04):-
- CountryChina
- Language:Chinese
-
Abstract:
E. coli mutant has been used as an assay organism for vitamin B12activity by many workers. The difficulty encountered in this method is theinterfering-action of metmonine. Fermented soybean products contain large.amount of this amino acid, thus the usual alkaline treatment method could not be used for the determination of vitamin B12 activity in these.products. A method for the separation of vitamin B12 from methionine has been developed by the authors. The sample extracted is prepared by the usual method and the extract passed through an active carbon absorption column, Then washing the column with pH 4.5 sodium acetate buffer solution removes methionine and finally vitamin B12 is eluted off with hot 65% alcohol Alcohol in the eluate is removed under reduced pressure and the methionine in the residue is in trace amount which can be corrected by the alkaline treatment. The recovery of vitamin B12 from the adsorption treatment ranges,from 95% to 101.3%, with an average of 98.8%.Nine kinds of Chinese -fermented soybean products have been assayed by this method. Fermented soybean curd with strong smell is a good dietary source of vitamin B12 activity, and it contains 1.88-9.80 r per 100 grams.
