Extraction procedures for the liquid chromatographic determination of thiamin, riboflavin and vitamin B6 in foodstuffs

Treatment with a mixture of enzymes (oc-amylase, papain and acid phosphatase) led to the release in a single step of the different forms (phosphorylated and protein-bound) of the vitamins B-1, B-2 and B-6 present in various food samples, not supplemented with vitamins. Analysis by means of HPLC/fluorimetry of the extracts obtained showed that the vitamin contents were at least as high as those found when the enzymatic treatment was performed with the aid of the most efficient diastase. Hydrochloric acid hydrolysis, very often combined with the enzymatic treatment and the role of which is to denature the proteins, proved to be superfluous owing to the presence of a protease in the mixture of enzymes used. When reference materials were analysed, the protocol of extraction proposed always made it possible to obtain vitamin contents in agreement with the certified values. (C) 2000 Elsevier Science Ltd. All rights reserved.