TITLE:
Phytoestrogen Enriched Tofu from Soybean Meal
AUTHORS:
Su Hyeon Hwang, Pushparajah Thavarajah, Dilrukshi Thavarajah
KEYWORDS:
Tofu; Soybean Meal; Isoflavone; Aglycone; Daidzein; Genistein
JOURNAL NAME:
American Journal of Plant Sciences,
Vol.5 No.3,
January
26,
2014
ABSTRACT: Isoflavone, a group of phytoestrogen, reduces postmenopausal symptoms and the risk of
osteoporosis of women. Glycosidic forms of isoflavones are presented in non-fermented soyfoods such as
tofu and they are less bioavailable than the aglycone isoflavones. Aglycone forms of isoflavones or more bioavailable
forms can be increased by acid hydrolysis during tofu processing. The present
study investigated the possibility of increasing the aglycone forms of
isoflavones by acid hydrolysis. We used five types of tofu in this study:
soybean tofu with hydrolysis, soybean meal tofu with hydrolysis, soybean tofu in general process, soybean meal tofu in
general process, and commercial tofu. Defatted soybean meal was used as the major
ingredient in the tofu which was made by using the new method—acid hydrolysis. To identify the
isoflavone quantities in all five types of tofu, high performance liquid
chromatography with diode array detection (HPLC-DAD) analysis was employed. The
genistein ratio between hydrolyzed tofu and standard tofu was 1:1-8, and the
daidzein ratio between hydrolyzed tofu and standard tofu was 1:6-12. The five
types of tofu were analyzed for the crude protein and micronutrients such as
calcium (Ca), magnesium (Mg), potassium (K), iron (Fe), zinc (Zn),
and selenium (Se) by the modified Kjeldahl method and inductively coupled plasma emission spectroscopy (ICP-ES),
respectively. The mean crude protein concentration of hydrolyzed tofu from soybean meal was
40.8%. In addition, especially the hydrolyzed soybean meal tofu showed the higher concentration
of Ca (27,307 mg/kg) and K (25,553 mg/kg). By and large,
soybean meal tofu with acid hydrolysis is a rich source of isoflavone aglycone
compared with other types of tofu.