Black and red rices (Oryza sativa L.) were analysed for total flavonoids and phenolics and the HPLC profile
including both free and bound phenolic fractions. Moreover, antioxidant activity and in vitro digestibility
was determined. Content of flavonoids and polyphenols as well as antioxidant activity was higher in free
phenolic fractions. Bound flavonoids in black rices were not significant contributors to antioxidant activity.
The main free phenolics in black rices were ferulic, protocatechuic and trans-p-coumaric acids, while
the major free phenolics in red rices were catechin, protocatechuic and caffeic acids. The main bound
phenolics in black rices were ferulic and vanillic acids and quercetin, in red rice types, they were ferulic,
syringic, trans-p-coumaric acids and quercetin. Newly, the presence of m-coumaric acid in red rices was
detected. Steam cooked rices showed very high levels of organic matter digestibility, whereas red rices
were significantly more digestible than black rices (p < 0.05)