Changes in Chemical Composition and Rice Cooking Quality Through the Utilization of Respiration Heat of Freshly Harvested Rice During Storage

Abstract

This study aims to determine the effect of the type of packaging and storage time on the chemical composition and rice cooking quality by utilizing the respiration generated heat of freshly harvested rice. “Siam Pandak” variety of freshly harvested rice stored in black plastic bag and tarpaulin with storage time of 0, 1, 2, 3, 4 and 5 days. The results showed that the accumulation of respiration heat of freshly harvested rice during storage is only capable of raising the temperature in the packaging up to 28 – 31°C, slightly higher than room temperature ranging between 26 – 29°C. Types of packaging and storage time could increase water absorption capacity, protein and fiber contents; and reduce fat and carbohydrate contents. The increase in water absorption capacity was obtained in black plastic bag with storage time of one day, which amounted to 298.27% (an increase of 27.74% compared to control), the highest protein content with storage time of two days with a protein content of 8.56% (an increase of 7.31% compared to control), fiber content in the tarp packaging with storage time of five days, which amounted to 2.40% (an increase of 96.46% compared to control).

Enhancing Paddy Rice Preservation in Small-Scale Barns: Comparative Analysis of Hot Air-Drying Techniques and Ventilation Impact on Quality and Energy Efficiency

“…Notably, during the final week, the temperature peaked at roughly 29 • C, noticeably surpassing the average ambient temperature, as depicted in Figure 8. This temperature elevation was likely due to the heat generated by the rice grains' respiration, similar to the observations made in the study on freshly harvested rice during storage, which highlighted the slight increase in temperature due to respiration heat, affecting various properties of the rice, such as water absorption capacity and protein content [28]. Nevertheless, this temperature surge during the early storage phase did not drastically influence the paddy moisture level, as indicated in Figure 8.…”

“…A noticeable increasing trend in pile temperature over time was evident, which might have been influenced by the seasonal transition from winter to summer. Despite this gradual increase, the monthly temperatures within the paddy stacks consistently stayed within the bounds of that month’s average ambient temperature, never surpassing 37 °C—a threshold supported by the study on the accumulation of respiration heat, highlighting the importance of maintaining specific temperature ranges to prevent nutritional degradation [ 28 ].…”

“…To counteract this heat buildup in paddy piles, it was crucial to introduce ambient air circulation to disperse this heat, particularly during the initial storage phase. The work of Millati et al [ 28 ] further supports this by highlighting that drying paddy rice in a single thick layer at low temperatures preserved the physical quality, physicochemical constituents, and starch morphology of rice grains, suggesting that controlled temperature and moisture are key to maintaining rice quality during storage [ 6 ].…”