Natural Aging of a Local Indonesian Rice Variety: Physical, Chemical, and Cooking Quality Analyses

Rice (Oryza sativa) of the Ciherang variety has been widely stored in warehouses for years as government food reserves. Storing rice for a long time causes a decrease in quality due to the natural aging process. This study is aimed at revealing the quality parameters most affected by the natural aging of rice during long-term storage (12-48 months). Changes in rice physical properties (including texture), chemical properties, and cooking quality were analyzed at 0, 12, 24, 36, and 48 months of storage, and Pearson correlation coefficients were calculated to determine the relationships between the parameters. Bulk density varied from 0.88 ± 0.00 to 0.79 ± 0.17 g/mL, insect excreta (frass), that is, secretions and metabolic residues from storage pests start from 0.00% ± 0.00% to 3.02% ± 0.70%, total dissolved solids from 245.33 ± 1.53 to 508.00 ± 83.07 mg/L, yellowness (b∗) from 12.13 ± 0.07 to 15.87 ± 0.19, free fatty acids from 0.26% ± 0.01% to 0.76% ± 0.06%, hardness from 7.73 ± 0.97 to 12.49 ± 2.09 kgf, cooking time from 23.40 ± 0.58 to 25.40 ± 0.44 min, and water uptake ratio from 3.70 ± 0.03 to 4.32 ± 0.34 g/g. Yellowness and total dissolved solids were significantly affected by storage time, exhibiting a strong positive correlation (r = 0.930, p < 0.01; r = 0.908, p < 0.01, respectively). In contrast, the water uptake ratio and free fatty acids were less influenced by storage time. The presence of foreign matter was strongly and positively correlated with both yellowness and the total dissolved solids. Mitigating yellowness and degradation of the grains is very important to maintain the quality of Ciherang rice during extended storage duration.