Effect of Whitener Type and Paddy Moisture Content on Rice Grain Damage During Milling Process

摘要

Rice (Oryza sativa L.) grain damage in common rice mills of Guilan province of Iran was evaluated. A factorial based on randomized completely design with three levels of moisture content of 8-9, 10-11 and 12- 13% (w.b.) and three types of universal rice whitener machines, abrasive type whitener (AW), blade-type whitener (BW) and frictional-type bladeless whitener (FBLW) was conducted in triplicates. A typical rice variety in Guilan’s paddy cultivated area namely Hashemi was considered. The obtained results indicated that the effect of moisture level and whitener type on the broken rice was significant (p<0.01). The lowest percentage of broken white rice (10.14%) took place in the AW with moisture level of 8-9%, whereas the highest percentage of broken rice (17.19%) was defined in FBLW with 12-13% moisture. The main effect of paddy moisture level and the whitener type on the cracked grains was significant (p<0.05). So that, the lowest percentages of cracked grains of 3.29% and 2.84% were measured in AW and paddy moisture content of 8-9%, respectively. It seems that using abrasive type whitener with paddy moisture level of 8-9% is the most proper choice for milling of Hashemi variety.