Antioxidant and antimicrobial activities and starch digestion rate of the organically- and non-organically grown traditional rice varieties in Sri Lanka

The study was designed to assess the total phenolic content (TPC), free radical scavenging activity, antimicrobial property and in vitro starch digestion rate of three traditional rice varieties grown organically and non-organically in Sri Lanka. The 70% ethanol extractions of rice were subjected to TPC, DPPH - free radical scavenging assays to determine antioxidant activity, and antimicrobial susceptible test against three bacteria, namely, Escherichia coli, Salmonella typhi and Staphylococcus aureus to determine antimicrobial properties. Starch digestion of cooked rice samples were evaluated under in vitro conditions. Both TPC and free radical scavenging activity was significantly higher (P<0.05) in organically produced traditional rice while the non-organically produced traditional rice samples showed a significantly higher (P<0.05) antimicrobial activity against S. typhi and S. aureus. There was no significant difference (P>0.05) in the in vitro starch digestion rate between the two groups. Though the study only considered traditional rice varieties, the results suggested that organically produced traditional rice samples performed better than those non-organically produced, with regard to the antioxidant properties such as TPC and free radical scavenging activity. The Madathawalu cultivar performed superior role in total phenolic content, free radical scavenging activity and Glycemic Index compared to that of two other traditional rice varieties, namely, Suwandel and Handiran.