Influence mechanism of tempering for storage quality of dried rice based on the evaluation of physicochemical and sensory characteristics and mitochondrial function and structure

Abstract

Use of tempering has proven to be effective for the improvement of rice milling quality, but few researches focused on its influence mechanism for dried rice storage quality. In this study, influence mechanism of tempering treatments [tempering at 65 °C (DTHT), 50 °C (DTMT) and no tempering (DTNT)] on the storage quality of two varieties rice (“Aolongsimiao” and “Shengtaiyou 018″) was evaluated based on the assessment of physicochemical and sensory quality, and a novel method judging the damage of mitochondrial function and structure in dried rice. During rice drying and storage, compared with DTNT and DTMT samples, DTHT samples showed the slowest increase in fatty acid value (FAV), nonanoic acid (off-flavor compound) content, cooked rice hardness, cross-sectional crack, and ratio of broken rice. DTHT samples suffered less oxidative damage, maintained significantly (p < 0.05) higher mitochondrial antioxidant capacities (MAC) and membrane integrity, and showed a less than 18.18% increase of mitochondrial malondialdehyde (MDA). Mitochondrial super oxide dismutase and MDA were significant correlation (p < 0.01) with moisture content, FAV, appearance, texture, comprehensive score, and stickiness of rice quality. Tempering influence mechanism for rice storage quality might be its maintaining MAC and membrane integrity, and then inhibiting the decrease of dried rice storage quality.