(1) Regarding the relationship between germination rate of hulled rice stored in normal- and low-temperature warehouses and elapsed months of storage, the germination rate of rice stored in normal-temperature warehouses decreased from 90% to 40% in August the next year and then to less than 20% in September. The germination rate of rice stored in low-temperature warehouses was still 80% in July, two years after harvest. From these results, it is assumed that a relatively high germination rate can be maintained through low-temperature storage under 10℃.
(2) Considering the relation between the germination rate and the taste, the higher the germination rate was, the better the rice tasted. The taste did not change very much if the rate was over 95%, but became worse with a decline in germination rate.
(3) With respect to the relation between the respiration rate of hulled rice and grain temperature, the respiration rate of rice was extremely low whether the grain temperature was increasing or decreasing, if the temperature was under 10℃.
(4) As a result of a test concerning storage conditions of unhulled rice for 10 months, it was found that the longer storage time was, the lower the evaluation values of rice quality became. However, the degree of degradation became smaller when the temperature was lower. Even in the comprehensive evaluation, it did not exceed tolerance limits after 6 months' storage at 5 to 10℃.
(5) Regarding the relation between storage temperature and the taste and smell, there was hardly any change in smell and only a little change in taste when the storage temperature was below 5
(6) Figure 3- 1 shows that low-temperature storage is superior to normal-temperature storage.
In Fig. 3-1, the value at the time of harvest is 100%. Looking at the changes in hardness/viscosity in the texturogram, while there was only a 5% decline from November to April in the next year in normal-temperature storage, the decline from April to October was 24%, almost 5 times larger than that of the previous 6 months. In low-temperature storage, there was a decline in the first summer but there was not much decline after that. While the decline of the TZ value (embryo activity) was larger in the second summer in both types of storage, the degree of decline was smaller, as was reducing sugar, in low-temperature storage compared to normal-temperature storage.
Table 3- 1 shows a comparison of average test values of different storage periods in normal- and low-temperature storage. It is obvious that low-temperature storage is superior to normal-temperature storage, and the effects of low-temperature storage increase with the elapse of storage time. In particular, the maximun viscosity of amylogram was stable, decline in viscosity of texturogram was small and those of reducing sugar and fatty acidity were also low.
Fig 3-1 Relation between storage temperature/period and taste3)
Table 3-1 Changes in taste properties by storage temperature3)
