2006 Volume 37 Issue 1 Pages 11-18
A wheat-grain classification method that uses size grading to reflect moisture content was developed for high-moisture-content grains. To grasp the relationship between grain thickness and moisture content and thereby fix the best grading size, the moisture content distribution of each thickness group and the consequent thickness distribution of grains were examined before and after drying. In addition, a rotary grader was used to perform a practical grading test.
Regarding pre-dried grain thickness, later harvested grain becomes thinner as it dries in the field. However, after drying, the later harvested grains are thicker as a result of their relative maturation. Observations of grain thickness and moisture content using a sieve by the Japanese Food Agency standard indicated that the best sieve size to separate high-moisture wheat grains is 3.0-3.4mm. The resultant two groups have higher and lower moisture contents. Tests using a rotary grader with 3.0, 3.2, and 3.4mm sieves indicated that a 3.2mm sieve is best for roughly equal separation of grains at around 35% moisture content. The grading capacity of high-moisture grain was about 30% of that of dried grain because of its high friction properties.
