Antioxidant Activity and Total Phenolic Content of Organically and Conventionally Grown Rice Cultivars Under Varying Seasons

Abstract

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

Distribution of Phenolic Compounds and Antioxidative Activities of Rice Kernel and Their Relationships with Agronomic Practice

“…The mean phenolic content of red or colored bran genotypes varies from 1.88 to 34.5 mg GAE/g in the above studies. It was noticed in our study that sample storage for certain period might bring nutritional properties deterioration as changes in metabolic activities or respiration increase cellular properties, unlike previous analysis of freshly prepared samples [ 8 ]. But, it also supports the idea of increased bioactive compounds under organic farming which is statistically equivalent to conventional rice ( P ≤ 0.05).…”

“…influence. It might be analytical methods or supernatant preparation that implies ready detection of these bioactive compounds in other studies [ 8 , 21 , 22 ]. In addition, the secondary metabolites content was reported to be much higher in rice bran [ 19 ] or pigmented rice [ 18 – 20 ] than light brown or white rice.…”

“…The isolation process of phenolic compounds in rice grains is carried by blending 2 g of rice flour with 80% ethanol (25 mL). The elaborated procedure of extraction followed discussed in our previous work [ 8 ] which was slightly modified version of Adom and Liu [ 9 ] and Zhou et al [ 10 ].…”

“…The estimation of phenolic compounds and antioxidants was following same procedure as given in our previous experiments on rice [ 8 ]. The TPC content was determined by Folin-Ciocalteu method [ 11 ] using a gallic acid standard; the TPC was calculated by a calibration curve.…”

Polyphenols in whole rice grain: Genetic diversity and health benefits

“…Organic farming is a form of agriculture that relies on techniques such as crop rotation, green manure, and biological pest control. Rice grain cultivated from organic farming has significantly higher antioxidant values than that from conventional farming (Kesarwani, Chiang, Chen, & Su, 2013). Therefore, organic rice grain production may produce rice with higher nutraceutical property without pesticide residue and heavy metal pollution.…”