This study was conducted to evaluate the distribution of total phenolic compounds and phenolic acids in the soluble and insoluble fractions of 10 rice (Oryza sativa L.) genotypes with pigmented or non-pigmented pericarp. These compounds were reported to exert beneficial effects on human health due to their high antioxidant activities. The total phenolic compounds (CFT) in both fractions was determined by the Folin-Ciocalteau method and phenolic acids RP-HPLC with Diode-Array Detection (DAD) in order to analyze phenolic acids. The amount of CFT in the soluble fraction was about 5.7 times higher in pigmented than in non-pigmented genotypes showing mean values of 3468 and 602 µg eq.ferulic acid/g rice, respectively. The presence of proanthocyanidins and anthocianins seems to be responsible for the higher amounts. The average amounts of CFT in the insoluble fraction was two-fold higher in the pigmented than in the non pigmented genotypes (825 e 378 µg eq. ferulic acid/g rice, respectively) probably due to the retention of antocyanidins and proanthocyanidins even after five consecutive extractions. Among the phenolic acids, the ferulic acid was the major phenolic acid found among all genotypes analyzed, except for the black pericarp in which the protocatechuic acid was predominant.
rice; Oryza sativa; cultivars; phenolic compounds; hydroxycynnamic acids; ferulic acid
