Effects of small-scale storage on the cooking property and fatty acid profile of sea rice paddy

Abstract

This research investigated the storability of sea rice paddy in an experimental silo for 11.5 months. Water was circulated in the silo walls from June 30 to maintain a grain bulk temperature of 23°C. The dry-bulb temperatures in three layers (top, middle, and bottom) of paddy bulk showed very small differences, but the intergranular air parameters such as relative humidity (RH), wet-bulb temperature and humidity ratio in middle and bottom bulk layers were significantly higher than those of top bulk layer, and storage insects occurred in these two bulk layers from August to September as a result that sulfuryl fluoride gas fumigation was done on September 30. During storage, the rice's water absorption rate and gruel solids loss decreased with storage time, while the peak temperature of gelatinization (Tp) increased, and water uptake ratio and taste panel score remained unchanged. Fatty acid profile analysis shows that the total, saturated, and unsaturated fatty acid concentrations decreased with storage time, while the unsaturated-to-saturated fatty acid ratio increased. Compared to top bulk layer, the bottom layer had lower water absorption rate and fatty acid concentration, and a similar Tp and better cooking property. Further compared with a short-grain Japonica paddy (cv. Yanfeng) stored in a large cooled warehouse before and after oversummering, sea rice paddy stored in the experimental silo had lower protein content, but had a higher Tp, poly-unsaturated fatty acid content and unsaturated-to-saturated fatty acid ratio, and similar amylose content and taste panel score. These results suggest that sea rice has good storability, and quasi-low-temperature storage (23°C) requires autumn chemical fumigation to control the storage insects.