The Relationship between Color Values in Rice to Phenolic Acids, Flavonoids, and Antioxidants

Thai rice is diverse. The seed coat manifests as multiple colors: white, yellow, brown, red, dark red, purple, dark purple, and black; dark-colored rice usually has a significant amount of antioxidants, far higher than those found in white or lighter variants. The aimed of this study was to find a simple, quick and economical way to assess phenolic acids, flavonoids, and antioxidants through color parameters, evaluating 12 varieties of various colors. The results showed L* values having strong negative correlations with almost all antioxidant parameters, except the IC50 value by DPPH assay. Antioxidant contents and antioxidant capacities demonstrated low correlation with a*, and b* had moderate negative correlations. Thus, L* values are the best data to assess other significant substances in rice, followed by b*. These results could be used to examine other compounds present in rice and may aid in the selection of varieties for cultivation. Keywords: Rice, Pigment, Phenolic acid, Flavonoid, Anthocyanin, Antioxidant