Abstract :
The aim of this study is to investigate the effects of two different types of milling machines (abrasive friction) and five milling times (30, 45, 60, 75 and 90 sec.) on total and head rice yield, whiteness degree, bran percentage, oil percentage of the produced bran, and nutrition constitutes of milled rice. The experimental work was conducted for two different rice varieties ( Short grain variety Sakha 104 and long grain variety Yasmin). The obtained results showed that, for both studied varieties, the total and head rice yields decreased with the increase of milling time. While, the abrasive type milling machine produced higher total and head rice yield in comparison with the friction type. Also for both types of milling machines, prolonged continuous milling (over 60 sec.) increased the whiteness degree of milled rice slightly, but brought about a drastic reduction in head rice yield. Meanwhile, the percentage of bran was increased while the percentage of extracted oil was decreased with the increasing of milling time for both types of milling machines and both rice varieties. Milling percentage, whiteness degree and grain transparency were increased with the increasing of milling time for both types of milling machines and both rice varieties. Also, as milling progressed from low to high degree of milling, the levels of protein, lipids, ash, and minerals decreased while the level of starch increased.
