PHYSICO-CHEMICAL AND TECHNOLOGICAL STUDIES ON SOME EGYPTIAN RICE VARIETIES

Abstract

The present study was carried out to evaluate different varieties of rice (Black, Sakha 105 and Egyptian Yasmen) as brown and white rice physically, chemically and technologicaly as well as to investigate the possibility of using their rice flour as substitution materials of wheat flour in preparing biscuits. The obtained results revealed that, physical properties of paddy, brown and white rice varied from one variety to another. It was found that E. yasmine had the longest length when compared with other varieties. It had also the lowest width among all of the tested ones, whereas Sakha 105 had the highest value in grain index. The paddy rice of raw E. yasmine had the highest percentages of broken kernels and the lowest percentages of head and white rice as compared with other rice varieties. Water uptake of white rice was significantly higher than that of brown rice. Brown black rice had the longest cooking time (38 min) compared to the others. Gel consistency (GC) varied significantly between varieties in both brown and white rice. Alkali spreading value in brown rice varieties showed lower values in comparing with white rice varieties. Black rice had the highest amylase content and the lowest pasting characteristics values than those of Sakha 105. Furthermore, Black rice contains high content of ether extract, ash and crude fibers, but lower content of total carbohydrate, compared with other varieties. In addition, brown rice of all varieties had higher contents of crude protein, ether extract, ash and fiber but lower content of total carbohydrates, whereas the rice variety of black rice had a relatively high levels of mineral contents comparing with the other rice varieties. Results of Organoleptic evaluation indicated that, biscuit samples prepared using rice flour of the studied varieties as substitutions insted of wheat flour up to 50% were very acceptable. Where most samples have sensory characteristics scores higher than those of control (wheat flour biscuit).