Thermal effects on the conversion of isoflavones in soybean
Journal
ACS Symposium Series
Journal Volume
1059
Journal Volume
1059
Pages
171-187
Start Page
171
End Page
187
ISSN
00976156
ISBN (of the container)
9780841225619
ISBN
9780841225619
Date Issued
2010-12-14
Author(s)
Lin, Pei-Yin
Abstract
Soybeans and soy-based products are getting popular in the world due to their nutritional and health-promoting benefits for human beings. The most human health related compounds in soys are isoflavones. There are twelve isoflavone conjugates existed in soybeans with different bioavailabilities and aglycones are reported to be the most effective one. The isoflavone profiles of soybeans can be changed by many factors, including the varieties of seed, pretreatments and thermal processing conditions. In this study, the effects of variety, pretreatment and thermal treatment on isoflavone profile of soybeans were evaluated. Two soybeans (KS1 and KS8) and two black soybeans (TN3 and TN6) grown domestically were soaked or germinated and followed by moist-thermal (121 °C up to 60 min) or dry-thermal (195 °C up to 30 min) treatments. The soaking and germination processes significantly increased the total amounts of isoflavones for 9-85%, depending on the soybean variety. During thermal processing, in general, malonylglucosides were significantly lost, corresponding with the increases of acetylglucosides and glucosides at early heating stage. Higher conversion ratio was found in dry-thermal process than in moist-thermal process. Aglycones could be effectively converted in matured soybeans after short dry-thermal treatment (10-20 min). For matured soybeans, the thermal processing is recommended for the conversion of aglycone conjugates from malonylglucosides, acetylglucosides, and glucosides. For soaked and germinated soybeans, dry thermal processing is not suggested due to its significant loss of total isoflavones and insignificant increase of aglycone conjugates after long heating time.
Other Subjects
Biochemistry; Carbohydrates; Heat treatment; Rapid thermal annealing; Black soybean; Conversion ratio; Heating stage; Heating time; Pre-Treatment; Pre-treatments; Related compounds; Thermal processing conditions; Flavonoids
Publisher
American Chemical Society
Type
conference paper