Harvesting time influenced the grain quality, phenolics, and total antioxidants of aromatic and non-aromatic rice

The study aimed to investigate the influence of harvesting time on brown rice, milled rice, and head rice recovery, amylose content, crude protein, total phenolic content, and total antioxidant activity of aromatic and non-aromatic rice. The experiment was conducted in irrigated lowland ecosystem in San Nicolas, Ilocos Norte and laid out in two-factorial Randomized Complete Block Design (RCBD) with three replications. The harvesting times include 25, 30, and 35 days after flowering (DAF, i.e. 50% of panicles flowered); while the two varieties were aromatic Burdagol- Laguna Type and non-aromatic PSB Rc 82 rice. The time of harvesting and variety and their interactions had significant effects on brown rice and head rice recovery, crude protein content, total phenolic content, and total antioxidant activity as measured by 2,2'-diphenyl-1- picrylhydrazyl (DPPH) radical scavenging activity. Burdagol-Laguna Type had highest brown rice and head rice recovery when harvested at 35 DAF and 30 DAF, respectively. PSB Rc 82 had highest head rice recovery at 25 DAF and highest total phenolic content at 25-30 DAF. Both varieties had highest crude protein content when harvested at 35 DAF and highest total phenolic content and % DPPH radical scavenging activity when harvested at 25 DAF. Harvesting PSB Rc 82 at 25 DAF was found optimum for all parameters except crude protein. Harvesting Burdagol- Laguna Type at 35 DAF was found suitable for brown rice and milled rice recovery, amylose content, and crude protein content, with moderate head rice recovery, total phenolic content, and % DPPH radical scavenging activity. Burdagol-Laguna Type had higher brown rice recovery harvested at 30-35 DAF and total phenolic content but had lower amylose content and % DPPH radical scavenging activity than PSB Rc 82. Differences in the responses between these aromatic and non-aromatic rice in terms of changes in grain quality and antioxidants with different harvesting times may be attributed mainly to their inherent genetic characteristics. Thus, it is important to determine the optimum harvesting time for aromatic and non-aromatic rice to attain the maximum grain quality and health benefits that are important to rice consumers.