Studies have shown that grinding different grains with the same mill under similar conditions results in products with different particle sizes.[27] The hardness of a grain sample is related to the percentage of fine particles obtained after grinding, with a higher percentage of fine particles from lower hardness grains.[28] Rose et al. (2001) discussed that hard endosperm produces irregularly-shaped larger particles, while soft endosperm produces smaller size particles. The correlation between particle size and energy consumed is although not positive but, to obtain very fine particle sizes require higher energy which reduces the rate of production.