Full-fatted and commercially defatted rice bran extracts (RBE and CDRBE) were evaluated for their ability
to inhibit enzymatic browning in potato and apple. RBE showed more effective inhibition of polyphenol
oxidase (PPO) activity and browning in potato and apple as compared to CDRBE. Five phenolic
compounds in RBE and CDRBE (protocatechuic acid, vanillic acid, p-coumaric acid, ferulic acid and sinapic
acid) were identified by HPLC. They were then evaluated for their important role in the inhibition using a
model system which found that ferulic acid in RBE and p-coumaric acid in CDRBE were active in
enzymatic browning inhibition of potato and apple. p-Coumaric acid exhibited the highest inhibitory
effect on potato and apple PPO (p 6 0.05). Almost all phenolic compounds showed higher inhibitory effect
on potato and apple PPO than 100 ppm citric acid