适碾精度下丝苗米加工品质的研究

Study on milling qualities of reasonable milled Simiao rice

为探究加工精度对丝苗米加工品质的影响,以5种丝苗米(19香、美香粘、澳丝粘、象牙香占、象竹香丝苗)为原料,控制碾磨时间进行加工制得理论碾减率为0.0%、2.0%、4.0%、6.0%、8.0%、10.0%、12.0%的米样,比较丝苗米在适碾(留皮度为2.0%~7.0%)和精碾(留皮度低于2.0%)范围内的加工品质。结果表明:与精碾相比,适碾精度下丝苗米整米率提高了2.96%~23.70%,留胚率提高了5.39%~165.98%,白度降低了11.95%~51.63%;丝苗米的整米率、留胚率随加工精度的提高而降低;对5种丝苗米碾减率与留皮度之间的关系分别进行数学建模,R2均在0.99以上;丝苗米的留胚率与整米率呈极显著正相关,白度与整米率呈极显著负相关(P<0.01);象牙香占在适碾时留胚率均远高于国标中规定的标准;从微观角度分析,当留皮度在2.0%左右时,丝苗米腹部的糊粉层几乎完全被碾去,背部存有极少量的糊粉层;使用40#砂辊、转速1060 r/min的碾米机,可以提高丝苗米的整米率和成品米的品质。适度碾磨是提高大米品质和企业经济效益的有效途径。

In this study,five kinds Simiao rice(19Xiang,Meixiangzhan,Aosizhan,Xiangyaxiangzhan,Xiangzhuxiangsimiao)were milled by emery roll whitening machine under different milling time,the theoretical degrees of milling(DOM)of 0.0%,2.0%,4.0%,6.0%,8.0%,10.0%,12.0%were realized.Then,the milling qualities of Simiao rice were compared between reasonable milling(DOM estimated by bran degree was 2.0%-7.0%)and well milling(DOM estimated by bran degree less than 2.0%).The correlation between different milling qualities was analyzed.The results showed that when the DOM of five kinds Simiao rice increased from well milled range to medium milled range,the head rice ratio increased by 2.96%-23.70%,the germ remained ratio increased by 5.39%-165.98%,the whiteness decreased by 11.95%-51.63%.The head rice ratio,the germ remained ratio of Simiao rice decreased with the increase of DOM.Mathematical model was carried out to determine the relationship between the DOM estimated by grain weight loss and the DOM estimated by bran degree,respectively.R 2 of fitted curves for the models were all above 0.99.On the other hand,the results showed the mathematical models had a good fitting degree.The germ remained ratio was significantly positively correlated with the head rice ratio,and the whiteness was significantly negatively correlated with the head rice ratio(P<0.01).The germ remained ratio of the xiangyaxiangzhan five kinds Simiao rice were much higher than the national standard in the reasonable milled range.In the SEM images,when the degree of bran retention was about 2.00%,the ventral aleurone layer of the five kinds Simiao rice was almost removed,while a very small amount of aleurone layer remained on the dosal part.When the milling degree was well milled,the dosal aleurone layer of Xiangyaxiangzhan had been completely removed,while there was still a small amount of dosal aleurone layer for Aosizhan.The head rice ratio and the quality of product could be increased when the rice mill equipped with No.40 emery roller at a speed of 1060 r/min.Excessive pursuit of the whiteness would lead to an increase in broken rice.Thus,reasonable milling was an effective way to improve the quality of product and the economic benefits of enterprises.