POSTHARVEST MANAGEMENT OF JAPANESE RICE IN WET SEASON

Abstract

Studies were made on postharvest managenent of Japanese rice grown in the North of Thailand. The aim was to minimize rice cracking occurred during various processes of postharvest management i.e. pre-thresh drying in the field, machine threshing, and drying with heated air.

It was found that field drying caused cracking approximately 20-25% and rewetting made the problem worse. However, threshing with peg-tooth drum thresher at 700-1100 rpm had little effect on both cracking and milling quality. The most promising drum speed for threshing TCC12 Japanese rice was 900 rpm which was equal to peripheral speed of about 1580 meter/min.

Drying with heated air also increased crack in rice kernel. The crack increased rapidly when the paddy was dried to 18% (wb) and lower. Nonetheless, when paddy was dried to 14% the kernel was harder than at high moisture content and resulted in higher head rice yield than of paddy milled without drying.

In postharvest management of Japanese rice in wet season, rewetting had obvious effect on milling quality while field drying and heated air drying had the most effect on kernel cracking. But surprisingly, the high percentage of kernel cracking found did not resulted in high percentage of broken rice after milling.