Comparison of folate losses in soybean during the preparation of tempeh and soymilk

Abstract

The changes in undeconjugated and total folate content of soybean during various stages of tempeh and soymilk preparation were studied. Total folate was extracted by the tri-enzyme technique. The ratio of total folate to undeconjugated folate was compared in all samples. Raw soybeans used for tempeh and soymilk preparation contained 4.04 and 4.50 mg total folate kg À1 respectively. Soaking and boiling soybean caused a significant loss of folate during tempeh and soymilk preparation. Leaching was identified as the major cause of folate loss, as soaking and cooking waters were found to contain a large amount of folate. Rhizopus fermentation of boiled soybean caused an increase of 68 and 100% in undeconjugated and total folate contents respectively. Frying reduced the folate content of tempeh significantly. Milling of boiled soybean in soymilk preparation significantly reduced the undeconjugated folate content of blanched soybean but increased the total folate. UHT treatment of soymilk caused a loss of 9 and 14% of undeconjugated and total folates respectively. The total folate content of deep-fried tempeh and soymilk was 2.35 and 2.76 mg kg À1 respectively. Analysed values are expressed on a dry weight basis.

Folates in Asian Noodles: II. A Comparison of Commercial Samples and the Impact of Cooking

“…During the analysis of the commercial noodles reported here, both free and total folate contents were measured, reflecting the approach used in many recent studies (Rader and others 1998, 2000; Shrestha and others 2000; DeVries and others 2001; Arcot and others 2002a, 2002b, 2002c; Johnston and others 2002a, 2002b). In summarizing the data, the proportion of free folate found was similar, and higher proportions were found in most of the dried noodles (Table 1).…”

Testing of folate conjugase from chicken pancreas vs. commercial enzyme and studying the effect of cooking on folate retention in Thai foods

“…The loss found in egg and fish could be due to the presence of polyglutamyl tetrahydrofolate (5-methyl-THF), which is the major unstable form of folate in these foods (Konings et al, 2001). On the other hand, the major forms of folate in soybean being naturally stable (having about 50% of folate monoglutamate and 42% of 5-formyl tetrahydrofolate, as referenced by Arcot et al, 2002b), the high retention of folate in cooked soybean was expected. A loss of 25% folate in cooked soybean was found in the present study.…”

Determination of folate contents in selected Indian foods using the tri-enzyme extraction and estimated folate intakes of the population based on 24-h recall

“…The fermentation is caused by air-borne wild yeast extremely rich in folate, contributing to the increase (Desikachar et al 1960). Similar studies with breads and tempe have reported twofold to fourfold higher folate values due to the fermentation process (Murata et al 1970;Hawkes and Villota 1989;Arcot et al 2002). Black gram dhal, an important component of both idli and dosa batters, is a good source of folate (132 mg/100 g in the raw) (Gopalan et al 2002).…”