Proximate composition
Moisture content was measured with a moisture analyser (MOC-
120H Shimadzu, Kyoto, Japan). Total nitrogen content was determined
following AOAC 920.87 semi-micro Kjeldahl method (AOAC, 1995).
The conversion factor 5.71 was used to transformnitrogen into protein.
Ash contentwas determined by the direct ashingmethod (AOAC, 2000).
Fat content was measured with a Soxtec apparatus (Soxtec™ 2050
FOSS, Hillerød, Denmark). Fat was extracted from 3 g of freeze-dried
okara with 90mL of petroleum ether at 80 °C for 120 min. The defatted
okara was collected and dried under nitrogen gas, and used for
subsequent non-volatile and antioxidant extractions. It was stored at
−20 °C before use. The combined carbohydrate and fibre content was
calculated by mass differences.