Abstract

Objective: To evaluate antioxidant properties of brans of twenty-nine red and white rice varieties of Sri Lanka. Methods: Brans of 21 new improved (NI), 2 old improved (OI) and 6 traditional red and white rice varieties of Sri Lanka were studied for range of antioxidant properties. The studied antioxidant properties included total polyphenolic content (TPC), ferric reducing antioxidant power (FRAP), oxygen radical absorbance capacity (ORAC), 2,2’-azino-bis(3- ethylbenzothiazoline-6-sulfonic acid) (ABTS) radical scavenging activity and 1,1-diphenyl- 2-picrylhydrazine (DPPH) radical scavenging activity in vitro. Bran of black rice variety from Korea was also studied for the same antioxidant properties for comparison. Results: Results exhibited significantly high ABTS and DPPH radical scavenging activities and 10, 7 and 2.5 fold greater TPC, FRAP and ORAC activities in brans of red rices (BRRs) compared to brans of white rices irrespective of NI, OI and traditional rice types. Among BRRs traditional varieties had greater ABTS and DPPH radical scavenging activities and 1.7, 1.3 and 1.2 fold respectively greater TPC, FRAP and ORAC in contrast to NI red rices. Traditional red rice varieties, Kalu Heeneti (TPC and ORAC), Pachchaperumal (TPC and DPPH) and Kurulu Thuda (DPPH) and OI red rice variety H4 (FRAP) exhibited the highest activities for the antioxidant properties studied. Further, these varieties had significantly high activities compared to black rice. Conclusions: In conclusion, BRRs especially traditional red rices had greater antioxidant properties and consumption may be useful in managing various chronic diseases.

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