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

T L H S Hemanthi,D A C K Dalukdeniya,C P Rupasinghe,R M U S K Rathnayake

doi:10.4038/sljfa.v3i1.41

Abstract

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.

Highlights

A dramatic increase of non-communicable disease related with food consumption, such as diabetes mellitus, cancers and food-borne illnesses have been reported in Sri Lanka in the recent years
DPPH value and total phenolic contents (TPC) The DPPH radical scavenging activity of the samples ranged from 16.89±0.78 to 4.55±1.85 mg ascorbic acid equivalent in 1 g of rice extraction (Table 1)
The highest mean DPPH activity was observed for MO while the lowest for SN rice sample

Summary

Introduction

A dramatic increase of non-communicable disease related with food consumption, such as diabetes mellitus, cancers and food-borne illnesses have been reported in Sri Lanka in the recent years. Rice (Oryza sativa L) is the staple food of 17 countries in Asia and the Pacific, nine countries in. The source and the amount of agricultural inputs may influence directly the level of available nutrients and indirectly to the physiology and chemical composition of the plant (Arab et al, 2015). It can be suggested that health benefits of rice grain may differ according to the agronomic practices. The importance of studying difference between organically grown and non-organically grown rice varieties is emphasized. This research was conducted with the major objective of evaluating the traditional rice varieties produced in two different agricultural systems in Sri Lanka, for their medicinally important bio-actives; antioxidant, anti-diabetic and antimicrobial properties

Materials and Methods

Results and Discussion

Conclusion