A New Conditioning Method with Half-dried Rice Storage and its Effects on Rice Qualities (II)

Qualities of Stored Rice which was dried after Temporary Storage

Abstract

This investigation was carried out to find out the effect of temporary storage on the qualities of rough rice which was dried to 15% moisture content after temporary storage. Half-dried rough rice of different moisture contents (20%, 18%, 17% and 15%) was obtained from the rough rice of different initial moisture contents (23.0%, 19.7%) by two types of commercial dryers (Tempering dryer and Continuous dryer), and was stored in 18 plastic bins. On 99th day after starting of temporary storage, a half portion quantity of samples was dried to 15% moisture content, and on the 165th day the remaining half portion of samples was dried to same moisture content. Both samples finished in this way were stored under the laboratory condititions for storage tests.
Storage stabilty was evaluated by measurement of temperature, moisture content, germination viability, mold population and fat acidity.
The temperature of initial rough rice was 16-4°C during temporary storage and was 8-11°C on 99-165th beginning of storage tests. Then it started to rise slowly with rising of room temperature and reached about 23°C at the end of storage tests. There was about 1% decrease in moisture content for all samples over the storage period. The germination viability of rough rices (below 18% moisture content) maintained over 80% T. Z. value, and percentage viability of stored samples for short period was higher than that of stored samples for long period.
The mold contamination of husked rice occured during temporary storage but molds populations did not increase in the half-dried rough rice dried to 15% moisture content. Some of the mold contaminations were lost mechanically during the drying proess. Changes of fat acidity were govered by moisture content of samples in temporary storage. Once the increasing tendency of fat acidity appeared, they were unable to be stopped increasing, even if samples were dried to 15% moisture content. Conversely some examples showed that fat acidity of samples increased after being dried to 15% moisture content. In other case, changes of fat acidity was influensed by the initial moisture content. Hereafter the authors intend to investigate the relation of the drying time of half-dried rough rice, the drying conditions and the initial moisture content of half-dried rough rice on the qualities of stored rice.