EFFECT OF DEGREE OF MILLING ON THE CHEMICAL COMPOSITION AND NUTRITIONAL VALUE OF THE MILLED RICE

The present investigation was carried out in 1998 and 1999 rice growing seasons to study the effect of different milling time on chemical composition and nutritional value of milled rice. Five Egyptian rice varie­ties and strains 1.e. Gin 177. Giza 178, Gz 1368, Sakha Inland Sakha 102 and three milling times (30'. 80* and 90") beside the brown rice were used. Protein content. crude oil. ash beside macro and micro nutri­ents (P. K. Mg. Zn, Fe, Mn and amylose content were measured at differ­ent milling time beside the brown rice. On the other hand cooking time, water absorption ratio (WAR) and volume expantion ratio (VER) ware also determined as cooking properties. The results snowed that all varieties &tiered signlicantly in re­gard to all studied chemical composition and mineral content when the brown rice samples of these varieties were compared. Mill2ng has a pro­found effect on rice composition, as non-starch consistuents decrease from surface to core of the grain. In general , Increasing degree of milling decreased the nutritional value of the milled rice by decreasing protein content, crude oil content and all macro and micro elements for all test­ed varieties. Protein content, oil content and ash content decreased sig. niticantly by Increasing milling time, however. amylose content increased by the same treatments. Both macro and micro elements contents also behaved by the same manner and decreased by Increasing milling time and this decrease ranged between 88.2% (tor Mn) and 48.44 % (tor Mg.). On the other hand, the cooking properties of the different varieties also affected by the milling time. Cooking time was decreased by in­creasing miffing time. however water absorption ratio and volume expan­sion ratio increased significantly.