Preparation of rice bran protein
Full-fat rice bran (Hitomebore, Japanese rice variety)
was purchased from a local rice store in Sendai, Japan.
Rice bran was defatted by extracting twice with three
volumes of hexane. Defatted rice bran (200 g) was
stirred in 2 L of 0.05 m NaOH for 1 h. The slurry was
centrifuged at 4000 · g, 4 C for 15 min. The sediment
was discarded and the supernatant was collected. The
pH of the supernatant was adjusted to 4.0 and allowed
to rest for 1 h at 4 C. The precipitate was washed twice
with distilled water by centrifuging at 4000 · g, 4 C for
10 min. The pH of the suspension was adjusted to 7.0
before freeze-drying. The resulted crude rice bran
protein (CRBP) was stored at 5 C.
Crude rice bran protein (10 g) was dispersed in
500 mL of 0.6 m HCl for 30 min, and then centrifuged
at 4000 · g, 4 C for 10 min. The supernatant was
discarded and the sediment was washed twice with
distilled water by recentrifuging. The resulted phytatefree
rice bran protein (PFRBP) was neutralised, lyophilised
and stored at 5 C until use. The antioxidative
activities of PFRBP and CRBP were examined.