Comparison of microbiological and HPLC-fluorescence detection methods for determination of niacin in fortified food products

A comparison has been made between results obtained by a recently published HPLC method, involving post-column reaction and fluorescence detection. wi th a microbiological assay using Lactobacillus plantarum. The HPLC method i ncludes a modified acid hydrolysis extraction step (0.1 M HCl) and yields n iacin values from fortified foods somewhat lower than by the microbiologica l assay. The most significant differences were observed for the cereal-base d products. These differences arise principally from the lack of specificit y of L. plantarum and from the stronger acid hydrolysis extraction conditio ns (1 M HCl) of the microbiological assay, which probably releases a part o f the non-bioavailable niacin. Moreover by HPLC, excellent recoveries of ad ded nicotinic acid and nicotinamide (95-100%) were obtained and better prec ision (RSDr = 0.3-0.8%) was observed than from the micobiological assay. (C ) 2001 Elsevier Science Ltd. All rights reserved.