Head rice yield response to low and high drying and tempering conditions

A b s t r a c t. The influence of drying and tempering conditions on head rice yield of long- and medium-grain rough rice varieties was investigated. The head rice yield values for the medium-grain variety at high drying conditions and 1.5 and 3% points moisture content removal were even significantly higher than the corresponding values for the long-grain variety at low drying conditions. 1.5% points moisture content removal yielded the least damage to the rough rice. Under low drying conditions, tempering had no meaningful effect on head rice yield for all drying durations. For both varieties, using high drying conditions with 6% points moisture content removal at first drying stage associated with 120 min tempering duration could be suggested as a rapid and energysaving operation to achieve high head rice yield values. K e y w o r d s: glass transition, grain drying, milling, moisture gradient, rice, tempering