Influence of Milling Time on Physical Properties and Proximate Chemical Composition of Some Egyption Rice Cultivars
Khaled M.H. Abd El Salam
The present study was conducted at Rice Technology Training Center (RTTC) to study the effect of milling time on physical properties and proximate chemical composition of some Egyption rice cultivars. Newly harvested certified seeds in 2014 and 2015 growing seasons of five rice cultivars namely, Sakha 103, Sakha 105, Giza 177, Giza 181 and Giza 182 were provided by Rice Research Training Center, Sakha, Kafr El-Sheikh, Field Crop Research Institute, Agriculture Research Center, Egypt. A split plot design with three replicates was used. The main plots were devoted to rice cultivars and the sub plots were occupied by different milling times (30, 50, 70 and 90 seconds). The results showed significant differences between cultivars for most studied characters. Comparison between means showed that rice cultivar Giza 177 gave the highest values for whiteness degree (37.72 and 38.26 %), grain width (2.92 and 2.88 mm) and grain thickness (2.16 and 2.12 mm) in 2014 and 2015 growing seasons, respectively. Moreover, the highest values for broken (13.97 and 14.86 %), grain length (6.4 and 6.27 mm) and grain shape (2.86 and 2.90 L/W) were noticed with Giza 181 rice cultivar in 2014 and 2015 growing seasons, respectively. Furthermore, Giza 182 rice cultivar gave the highest values for crude protein (8.07 and 8.25 %) and starch (75.38 and 75.65 %) in 2014 and 2015 growing seasons, respectively. Sakha 105 rice cultivar showed the highest values for rice bran (8.78 and 9.17 %) in 2014 and 2015 growing seasons, respectively. Increasing milling time from 30 to 90 seconds significantly increased rice bran %, broken rice %, whiteness degree %, grain shape and starch % while, significantly decreased milling %, grain length, grain width, grain thickness, crude protein %, crude fiber %, crude fat %, ash % and non starch polysaccharides %. Interaction between cultivars and different milling times indicated that the highest rice milling (75.31 and 75.62 %) was recognized with Sakha 105 rice cultivar and milling time 30 seconds.
Keywords: Rice, bran, milling time, milling degree, whiteness, grain quality, rice cultivars