On Moisture Content of Rice : 1. Hygroscopic equilibrium of rice in relation to the grain texture.

Abstract

The studies were undertaken to explore the relation between equilibrium moisture content in kernel and the grain texture in several varieties of rice and some kinds of kernels at high, medium and low relative humidities. 1. The soft varieties those have somewhat soft and coarse portion in their endosperm tissues<> approach to higher equilibrium moisture contents at high relative humidity, but to lower equilibrium moisture contents at lower relative humidity in comparison with the hard varieties. (Table 2, Fig. 1, Fig. 2). 2. Chalky kernels and other unfully ripened kernels approach to higher equilibrium moisture contents at high relative humidity, and to lower equilibrium moisture contents at low relative humidity in shorter duration than normal kernels, because those Kernels have the soft and coarse portion in the outer tissue of endosperm. (Fhg. 1, Fig. 3). 3. Generaly, at the same relative humidity, equilibrium moisture content is lower at high temperature than at low temperature1). The soft varieties are more sensitive to these effects of temperatures, therefore, equilibrium moisture contents in them are higher at high relative humidity and low temperature and are lower at low relative humidity and high temperature in a marked degree than those in hard varieties. (Fig. 4, Fig. 5). 4. At the same relative humidity, equilibrium moisture contents is lower in brown rice than in polished rice because the moisture content of bran is lower than polished rice at usual relative humidity (lower than 80%). (Fig. 6).