Effects of processing on folate retention in food

A number of studies in the literature have reported thermal destruction of folate in model systems when temperatures were up to 100°C and under UHT conditions, and in food systems. In particular, the concentration of folic acid and 5-methyl tetra hydro folate (THF) were followed. Given the different extraction methods used for folate analysis using the microbiological assay, data vary largely. The traditional technique using single enzyme method on cereals, in particular, gave one third to almost one half of the amount of folate detected by the tri-enzyme method. Common processing methods in such as boiling, fermentation, roasting and baking, where heating may be dry or moist, caused considerable losses of folic acid in foods. Several studies on effects of the baking process on wheat products (eg. bread) have been done on pilot scale and it is generally agreed that despite the increase in folate during fermentation, total folate is lost due to the high baking temperatures employed. Other studies reveal a loss of 40% of total folate during commercial soy milk processing compared to the total folate concentration in the raw beans (1). This paper will analyse existing data on the effects of processing keeping in mind the differences in extraction methods used for folate analysis in foods.