THE THIAMINE, NIACIN, RIBOFLAVIN AND PROTEIN CONTENTS OF RICE USED IN CANTON

The first part of the work consists of thiamine analysis of 5 allotments of rice samples bought from retail shops in various districts in Canton from the end of 1954 to the beginning of 1957. Usually seven grades of rice are available, and the grades differ both in variety and extraction rate.It is found that the thiamine content of rice bought at the same time, or of the same grade bought within a few months may vary considerably. Two-third of the samples contain 0.11 to 0.18 mg of thiamine per 100 g of rice but it takes the range of 0.05 to 0.27 mg per 100 g to cover all the samples. With the exception of the lowest grade, the thiamine content in general increases with the lowering of grade and decrease of price.The second part of the work studies the influence of variety and of extraction rate upon the thiamine, niacin, riboflavin and protein content of rice. Seven varieties of rice commonly used for the seven grades extracted at different rates are obtained from a local rice mill by special arrangement with the City Food Bureau. 'Results show that milling decreases the content of these 3 vitamins and of protein, the decrease for thiamine and niacin being greater than for the other two nutrients. However, not only the original content of these nutrients in husked rice may vary, but also their degree of loss in milling may differ. Of the varieties studied the lowest grade of husked rice contains the greatest amounts of all the four nutrients while the Super Grade A tends to lose the least during milling. As a result, the milled products of these two varieties tend to contain slightly larger quantities of these nutrients.