The common phenolic acids in rice include ferulic and p-coumaric
acids, which belong to the hydroxycinnamic acid group. In addition to this group, caffeic,
chlorogenic and sinapic acid have also been identified.Other compounds
from the hydroxybenzoic acid group that are present in rice are
p-hydroxybenzoic, vanillic, syringic and protocatechuic acids.In addition to the two major acid groups discussed above,
aldehyde analogues such as vanillin, protocatechuicaldehyde
and p-hydroxybenzaldehyde are also referred to as phenolic
compounds.