RESUMO
The thiamine and nicotinic acid content of the husked rice (whole rice) samples from 9 representative varieties of paddy collected from Jiangsu and Zhejiang provinces were analyzed, and the effect of degree of milling on the content of these two vitamins were studied. The paddy samples were husked with wooden mill and the husked rice samples were milled with laboratory rice mill to 5 grades, namely, "96", "94", "92", "90" and "88" percent extraction (by 96% extraction we mean 96 grams of finished rice were derived from 100 grams of husked rice), and the thiamine and nicotinic acid content of each sample were determined. It is found that the thiamine and nicotinic acid content of the rice of different variety may vary considerably, and both were decreased with the increase of degree of milling. Generally, above the "94" grade, the loss of thiamine is higher than that of nicotinic acid, while down from the "92" grade, less thiamine and more nicotinic acid were lost. The rate of decrease in nicotinic acid content is relatively irregular as compared with that of thiamine, and different varieties are affected differently by the milling process.