Cereal Chem 48:369 - 372.  |  VIEW ARTICLE
Nutrient Composition of Selected Wheats and Wheat Products. VII. Total and Free Niacin.

F. N. Hepburn. Copyright 1971 by the American Association of Cereal Chemists, Inc. 

A total of 165 samples were analyzed for their content of total and free (unbound) niacin. The samples included 10 types of wheat foods obtained from each of 2 cities in each of 5 geographical areas of the country (100 samples) and an additional 56 samples comprised of 11 wheats, flour milled from those wheats, and products prepared from the flours. Total niacin was measured according to a conventional procedure. Free niacin was determined by Lactobacillus plantarum assay of aqueous extracts. Most niacin of enriched products was found in the free form (85 to 90%), whereas that of unenriched products was approximately one-half free niacin. The distribution of niacin was consistent for commercial products, and showed no variation with geographical source. Although both total and free niacin of wheat was reduced by milling, a greater proportion of free niacin was retained in each flour. Moreover, the proportion of niacin in the free form was higher in bread, cakes, and crackers than in the flours from which they were prepared.