Improved antioxidant activity of BKOS Thai jasmine rice

Abstract

Thai jasmine rice (Oryza sativa L. cv. KDML105) is highly valued due to its subtle aroma, robust seed characteristics and high nutritional quality. Low-energy ion-beam bombardment was chosen to improve the quality of jasmine rice by mutation induction. One mutated variety, named BKOS, was found to exhibit a deep purple colour due to an increased accumulation of anthocyanin. The total phenolic content and antioxidant activities of cooked and uncooked rice extracts were compared with KDML105, BKOS and other rice mutants created by a low-energy ion beam. The BKOS extracts showed the highest total phenol content (0.140 and 0.096mg of gallic acid equivalent (GAE) g-1dry extract from uncooked and cooked rice, respectively). The BKOS extracts also had improved antioxidant activities, determined using three standard methods: 2,2′-diphenyl-1-picrylhdrazyl (DPPH) free radical scavenging, ABTS radical cation (ABTS•+) decolourisation and ferric-reducing antioxidant power assays. BKOS extracts showed 2-2.5-fold increased levels for each method. Interestingly, there was no significant difference between the antioxidant activities of the cooked and uncooked BKOS rice extracts. The increased quantity of antioxidants in this anthocyanin-based natural product could allow antioxidants to be consumed by a wider population than what is currently possible. © 2012 Taylor & Francis.