DETERMINATION OF THE FOLIC-ACID CONTENT OF GRAIN, CEREAL PRODUCTS, BAKERY PRODUCTS AND LEGUMES BY MEANS OF HIGH-PERFORMANCE LIQUID-CHROMATOGRAPHY (HPLC)

The folic acid content of grain, cereal products (including beer), bakery products and legumes was determined by means of high-performance liquid chromatography (HPLC). Free folate (monoglutamate forms) and total folate (monoglutamate + polyglutamate forms) were differentiated. Of the grain analysed, rye, with a mean value of 143 mu g/100 g, contained more total folate than wheat (mean=91 mu g/100 g). The total folate content of bakery products ranged from 14 mu g/100 g (whole grain rye bread) to 88 mu g/100 g (crispbread). Beer had a very low total folate content (mean=3 mu g/100 mi). The mean of the free folate portion was 76.5% in grain and cereal products and 65.6% in bakery products. Of the legumes analysed, beans (mean=128 mu g/100 g) had the highest,content of total folate, followed by lentils (103 mu g/100 g) and peas (57 mu g/100 g). The mean value of the free folate portion in legumes (73.1%) was comparable with the values of grain, cereal products and bakery products. In addition to tetrahydrofolic acid (THF), 5-methyl-THF and 5-formyl-THF, pteroylglutamic acid (PteGlu) and 10-formyl-PteGlu were determined in all products (except beer). Their proportion (PteGlu+10-formyl-PteGlu) of the total folate content ranged from 23.5% to 44.4%.