The phenolic and antioxidant activity of ethanolic extract of two Japonica rice cultivars, Taikeng no. 16 (medium and slender grain) and Kaohsiung no. 139 (short and round grain), grown under organic and conventional farming were examined. Analyses shows that Kaohsiung no. 139 contains the highest amount of secondary metabolites and continuous farming can increase its production. Results also suggest that phenolic content under different agronomic practices, has not shown significant differences but organically grown rice has proven to be better in higher accumulation of other secondary metabolites (2,2-diphenyl-1-picrylhydrazyl (DPPH), flavonoid content, and ferrous chelating capacity). In nutshell, genetic traits and environment have significant effect on phenolic compounds and the least variation reported under agronomic practices.

The secondary metabolites of milled rice influenced by agronomic practices, seasons and their interaction effects were investigated. The ethanol extracts of rice grains in two japonica cultivars were analyzed with different assays to measure the total phenolic content, reducing power, radical-scavenging activity and chelating activity. Similar to earlier studies of phytochemicals, significantly higher antioxidant values were recorded in the organic rice. Second crop (November/December) in comparison with first crop (June/July) had significantly higher values of antioxidant activities, except for the chelating effect. The interaction between the agronomic practices and seasons had a detrimental effect on the crops because the combined factors had a more significant role than each factor alone. Even with the alterations in their content, polyphenols were positively correlated with the antioxidant activities, with the exception of chelating activity, when considering both factors (agronomic practices and season). PRACTICAL APPLICATIONSOur investigation focused on marketed milled rice which had been underestimated or neglected for the secondary metabolites production in earlier studies. The experiments were conducted on commercially available milled rice for analytical comparison of organically and conventionally grown two japonica rice cultivars for phenolic compounds and antioxidant activities. The result described the positive behavior of milled rice toward the organic farming which enhanced the phytochemicals content and reported higher levels than conventionally grown rice on average. Furthermore, the amounts were higher during winter season as compared with the summer period. The results provide information that the organically grown milled rice could be a potent natural antioxidant to protect against oxidative damage in regular diets while assuring sustainability and food safety. bs_bs_banner Journal of Food Biochemistry