Abstract

This study was aimed to proof that fermentation could increase phenolic and anthocyanin contents, antioxidant activities and antimutagenicity of Thai pigmented rice. Six cultivars of rice (Sung Yod, Mon Poo, Hom Mali Daeng, Hom Nil, Riceberry, and black glutinous rice) were fermented with a mixed culture of yeasts and molds (Look-Pang) at 30°C for 3 days to produce six types of fermented rice (Khao-Mak). Each sample exhibited significantly higher total phenolic and anthocyanin contents as well as antioxidant activities, including 2,2′-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity, ferric reducing antioxidant power (FRAP), than that of the unfermented one of the same variety. Neither fermented nor unfermented pigmented rice substituted for corn flour in the fly medium was mutagenic in the somatic mutation and recombination test using Drosophila melanogaster. Interestingly,the antimutagenicity of fermented rice against urethane in the same testing was proven to be greater than that of its corresponding unfermented rice. This might be due to the higher content of total phenolic compounds, anthocyanins and antioxidant activities in fermented rice probably because of the catalytic action of enzymes produced by the starter organisms during fermentation which are capable of hydrolyzing glucosides of the inactive components to the active aglycones.

Key words: Fermented rice, total phenolic, anthocyanin, antioxidant activities, antimutagenicity.