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.

The change of the ascorbic acid content in several vegetables at the different steps in the cooking process was studied. Special attention was directed to washing before or after cutting the vegetable into pieces of different size.Large-scale and household cooking methods were compared. The effect of storing the cooked vegetable at different temperatures and for different lengths of . time was also investigated.The loss of the total and reduced ascorbic acid in spinach, colza, cabbage and celery cabbage was insignificant after washing either before or after cutting. The loss was also not appreciable when these vegetables were held for 2 and 6 hrs. after cutting into wedges. When potatoes and cabbage were cut into strips, there was no change in the total ascorbic acid but a slight decrease of the reduced form. A marked loss of total ascorbic acid was observed when potatoes strips and slices were soaked in water; the slices lost 11.2% and 12,.8% and the strips lost 22.6,% and 23.9% respectively by the end of 2 and 6 hrs. When potatoes were cut and kept in the air at room temperature for 2 and 6 hrs., there was no change in total ascorbic acid, but an increase of the reduced form was apparent. Such an increase should not be attributed to the so-called "traumatic formation"; some changes in the redox system of ascorbic acid is to be expected.A certain amount of ascorbic acid was lost when'spinach, garlic green, colza and celery cabbage were cooked either in large or in small quantities. The retention of the reduced ascorbic acid in the vegetables cooked in small quantit ies ranged 50.2-64.1.%, and that of the total ranged 72.6-75.7%. In case of the large-scale cooking, the retention of reduced and total ascorbic acid ranged 53.6-70.5% and 73.9 - 85.4% respectively. No loss of ascorbic acid was observed when the potatoes were steamed whole, but a large amount was lost when their strips were scrambled in a Chinese style.Cooked vegetables held at 60℃ for 2 and 4 hrs. lost a part of its ascorbic acid; the percentage of loss in the 2 hr. period was lower than that in the 4 hr.

Husked and milled rice samples were prepared with laboratory rice mill from 23 representative varieties of paddy collected from the main rice production areas of China. All the samples were analyzed for the contents of protein, fat, crude fiber, ash, calcium, phosphorous, thiamine, riboflavin and niacin. The nutrient content of husked rice varies with variety and locality of growth. The range of protein content of the husked rice samples ranged from 6.7% to 9.6%.Rice samples had been analyzed at successive stages of milling for studying the effect on the nutrient content of milled rice. Results of this investigation showed that nutrient content declines progressively during the process of milling. While the protein content decreased insignificantly, the other nutrients, especially thiamine, ash, phosphorous, crude fiber and fat, were lost to a greater extent. In order to keep the thiamine content of polished rice not less than 0.15 mg %, the authors advocated that the overall weight removed during milling should not exceed 9-10% of the weight of husked rice.