STUDIES ON THE MICROBIOLOGICAL ASSAY OF PHENYLALANINE
- VernacularTitle:食物中苯丙氨酸的微生物测定法
- Author:
Kwangchi YANG
;
Hsingchuan CHENG
- Publication Type:Journal Article
- From:
Acta Nutrimenta Sinica
1956;0(02):-
- CountryChina
- Language:Chinese
-
Abstract:
Casein was hydrolysed with sulphuric acid under pressure and the hydrolysate was oxidized and nitrated by a mixture of sulphuric acid and potassium nitrate. After decolorization and neutralization to pH 4, the residue was removed by filtration.After adjusting the filtrate to pH 6.8 and supplementing it with tryp-tophane, cystine, methionine, and tyrosine, it was used as the source of amino acids ill the preparation of the medium for the microbiological assay of phenyl-aianine with Lactobacillus ardbinosus 17-5 as test microorganism.The standard curve shows that the medium is almost free from active phenyl-alanine, for blank values are of the same magnitude as those of a synthetic medium.Increasing the quantity of nitrated casein hydrolysate from 8 g. to 10 g. doesnot cause any difference in acid production. Further supplementation of themedium with fustidine, arginine, and lysine is also without effect.The results obtained by analyses of several foods with the present medium and the findings of Sauberlich and Baumann (1946), and Schweigert (1944) are in
