EFFECT OF PARBOILING PROCESS ON MILLING QUALITY, PHYSICAL AND CHEMICAL PROPERTIES OF TWO RICE VARIETIES

Abstract

The present study was carried out to investigate the effect of parboiling process on physicochemical, nutritional properties, Milling quality and organoleptically of brown and white rice. The obtained results revealed that, physical properties of brown and white rice varied from one variety to another. Giza 182 rice variety was significantly the longest length among Giza 179 rice variety. In addition, parboiling process had no effect on the length and width of either brown or the white rice at P ≤ 0.05.The paddy rice of raw (Giza 179) had the highest percentage of broken grains and the lowest percentages of head rice and Brown rice as compared with (Giza 182) variety, where parboiling process led to decrease the percentage of broken rice from 32.40 to 4.28% for Giza 179 and from 16.50 to 5.50 for Giza 182.In addition, parboiling process help to increase the head rice and white rice percentages. Water uptake, sedimentation value of white rice were significantly higher than that of brown rice. white rice variety of Giza 179 had the lowest cooking time among all of the tested rice samples (17 min.). water uptake and sedimentation values decreased as a function of parboiling process but cooking time increased for all rice samples. Gel consistency (GC) varied significantly among varieties in both brown and white rice. Alkali spreading value in brown rice varieties showed lower values in comparing with white rice varieties. white rice variety of Giza 182 had the highest Alkali spreading value, Elongation and Amylose content among the other varieties. Moreover, it were decreased upon subjecting rice to parboiling process. Brown rice of two rice varieties had higher contents of crude protein, ether extract and ash but lower content of total carbohydrates than those of white rice. Parboiling process lowered the percentage of the crude protein and ether extract in both brown and white rice .whereas, it increased the ash and minerals content in white rice samples. The cooked white rice of Giza 182 variety had the highest mean scores for the palatability characteristics among all of the tested rice samples. In addition, parboiling process helped to decrease the mean score for the palatability characteristics but the values were still acceptable by the panelists.