Research Of Rice Drying Characteristics And Quality On Drying In Time

Drying for post-harvesting rough rice is necessary for its processing and storage, which has influence on the head rice yield and taste quality of milled-rice. Drying in time is to perform immediately drying treatment for the rough rice after harvesting. It may remain the the "activity" and improve taste quality of rice. At present, the advantages of drying in time have been mentioned in domestic and international research, but there is a lack of systematic studying on the property, quality and process for drying in time.Contrast method was adopted to study the characteristic and quality of rough rice by drying in time or in stacked. For the rough rice by the different harvest dates (in2010and in2012), effect of drying temperature were investgated on the drying rate, crack rate, taste quality and texture characteristics in the process of drying in time and in stocked. The optimal drying conditions and harvest date were determined according to the drying qualities. The conclusions are obtained as follows:1. The moisture content of rough rice is continued to be reduced with harvest date. At first frost date the moisture content was reduced to below15%. When the initial moisture content of rough rice was high (within8days from rice mature period) after harvest, the drying rate for the drying treatment after stacking3day was better than that for drying in time. However, when the moisture content of rough rice is low (8days later from rice mature period) after harvest, the influence of stacking time on drying rate was not significant.2. There was no significant difference for head rice yield between drying in time and deferred drying. And the effect of stocked time on head rice yield was no significant. However, influence of drying temperature on head rice yield was significant, and head rice yield sharply reduced with the increase of drying temperature. The effect of harvest date on head rice yield was significant. With the progression of harvesting date, head rice yield was first increased and then decrease. Head rice yield achieved the highest level when rough rice harvest occurred in the8th days from mature period.3. In the low-temperature drying conditions of40℃, the taste value was higher than that in drying temperature of50℃and60℃.For.the dying temperature at40℃, the taste quality obtained by drying in time was better than that obtained by drying in stocked before frosting, and the taste quality was deterioration with the increase of harvest date, while the taste value was no significant between two drying methods after frosting. For50℃drying temperature, when the rough rice harvest occurred at the beginning of mature period within8days, the taste value obtained by drying in time was better than that obtained by drying in stocked, while for other conditions, there were no significant influence. For the dying temperature at60℃, the taste value was not changed obtained by drying in time and in stocked. The influence of harvest date was significant on taste value. For40℃drying temperature, the taste value was increased and then decreased with the increase of harvest date, and the optimal value occurred at8th day of mature period. For the dying temperature at50℃, the change of taste value was not uniform, but the optimal value occurred at8th day of mature period. There was no significant change for taste value of rough rice with harvest date for60℃drying temperature.