[Effect of technical threonine sources on homoserine biosynthesis by mutant Brevibacteruim flavum 2T]. / Vliianie tekhnicheskikh istochnikov treonina na biosintez gomoserina mutantom Brevibacterium flavum T 2T.

The effect of threonine technical sources on the homoserine biosynthesis by the threonine auxotroph Brevibacterium flavum 2T when cultivated on sucrose and acetic acid containing media was investigated. Various threonine sources (corn extract and fodder yeast, microbial biomass and soybean meal hydrolyzates) prepared by means of different hydrolyzing agents (acids, enzymes, autolysis) were used. The most effective substrate was protein--vitamin concentrate hydrolyzate, particularly combined with corn extract in the ratio 1: 0,25-0.5 (with respect to the dry weight of the initial material). The homoserine yield was 16.2 g/l on the sucrose containing medium and 18.4 g/l on the acetic acid containing medium which was in agreement with controls. The medium containing pure threonine was used as a control. With other threonine sources (corn extract, protein-vitamin concentrate autolyzate and enzymolyzate, fodder yeast and soybean meal hydrolyzates), the homoserine production was significantly lower, i.e. 40-70% of the control. The content of amino acids (threonine, isoleucine, methionine) in the initial material and their suitability for the homoserine biosynthesis were found to be correlated. The substrates with a high content of threonine (over 3.5%) and a low content of methionine (below 0.5%) proved most effective. The use of the material in which the ratio threonine: methionine was less than 6.0 caused the homoserine biosynthesis to be partially replaced with that of lysine.

[Effect of the technological and culinary preparation on vitamin preservation in fish and in nonfishery products]. / Vliianie tekhnologicheskoi i kulinarnoi obrabotki na sokhrannost' vitaminov v rybe i produktakh nerybnogo promysla.

The content of vitamins A, E, C, B6, thiamine, riboflavin, niacin and folacin was studied comparatively in some fish species during their preservation as frozen, salt and smoked products. The thiamine content was found to decrease during preservation of frozen and salt fish, while in smoked fish it preserved better. The uncut salt and smoked fish showed an increased content of vitamin A in its edible part at the expense of redistribution together with fat from the internal organs. The boiling of fish and non-fishery products changed the content of some vitamins. Vitamin losses were due both to their destruction at boiling and passage into the broth.

[Determination of folacin in the liver with the use of its enzymes]. / Opredelenie folatsina v pecheni s ispol'zovaniem ee fermentov.

A method of instituting hydrolysis by using enzymes of the examined liver is proposed as an adjunct to the formerly elaborated fluorometric procedure of determining folacin in the liver. The fermentative hydrolysis is conducted in two stages. The purpose of the first of them is to split the combined form of folacin under the effect of the examined liver conjugases; the second stage involves transformation of xanthopterin contained in the liver into leucopterin by xanthinoxidase of the liver. When utilizing enzymes of the examined liver the need for producing and application of the enzymatic preparation made of the pig kidneys falls away, this simplifying the fluorometric determination of folacin in the liver and increasing its accuracy.

[Vitamin concentration in different varieties and grades of cabbage]. / Soderzhanie vitaminov v razlichnykh vidakh i sortakh kapusty

Examinations covered 8 varieties (28 grades) of cabbage for the content therein of C, B6 vitamins, beta-carotene, thiamine, riboflavin, niacin and folacin. All the cabbage specimens were analyzed right after picking. In 2 grades of the cabbage vitamins were determined after picking and repeatedly after storage (9 months in a vegetable storehous). It was found that there existed a significant difference in the quantitative content of vitamins between individual varieties of cabbage. The proportion of all the vitamins is noteceably higher in broccoli, Brussels sprouts and in cabbage lettuce. Brussels sprouts are distinguished by a particularly high level of vitamins.

[Folacin determination in the blood by a fluorimetric method]. / Opredelenie folatsina v krovi fluorimetricheskim metodom

To determine the blood folacin a fluorometric method is proposed. This includes the following stage-wise operations: liberation of combined forms of folacin under the effect of enzymes contained in the blood investigated; quantification of tyrosine to make a correction for changed fluorescence intensity of this amino acid during oxilation of the solution; measurement of the fluorescence of the substances present in the solution before and after their oxidation with potassium permanganate and calculation of the folacin content. The fluorometric method enables it to greatly speed up the assay by comparison with the microbiological method of determination with the Lactobac. casei as a test-organism, the assay time being cut down from 4-5 days to 4-5 hours without prejudicing the accuracy of the determination.