Effects of fermentation temperature on the content and composition of isoflavones and beta-glucosidase activity in sufu.
Sufu is a popular fermented tofu product in China. The low quality of sufu produced in the hot summer is a big problem in sufu manufacture, so we prepared sufu at two different temperatures, 26 degrees C as normal and 32 degrees C as high temperature, and the effects of temperature on isoflavones and beta-glucosidase activity were investigated. Fermentation temperature did not cause significant differences in the recovery of isoflavones, but resulted in a different redistribution of isoflavone isomers in sufu. Sufu fermented at 26 degrees C was richer in isoflavone aglycones than at 32 degrees C; the enrichment of isoflavone aglycones might have the advantage of enhancing the physiological function. No 6''-O-malonyl-glucosides were detected in sufu fermented at 26 degrees C, whereas some 6''-O-malonyl-glucosides were found at 32 degrees C. A fermentation temperature of 26 degrees C benefited the beta-glucosidase production by fungi, which contributed to valid conversion from beta-glucosides to aglycones. It was also found that beta-glucosidase converted beta-glucosides more effectively than 6''-O-malonyl-glucosides and 6''-O-acetyl-glucosides into aglycones.
Yin
Li-jun
LJ
College of Food Science and Nutritional Engineering, Box 40, China Agricultural University, Beijing, China.
Li
Li-te
LT
Liu
Huan
H
Saito
Masayoshi
M
Tatsumi
Eizo
E
D005285:Fermentation; D007529:Isoflavones / Q000032:analysis*; D045730:Soy Foods / Q000032:analysis*; D013696:Temperature; D013997:Time Factors; D001617:beta-Glucosidase / Q000032:analysis / Q000378:metabolism*
D007529:Isoflavones; D001617:beta-Glucosidase