不同品种糯米浸泡前后的理化特性比较

为了研究浸泡处理对糯米理化特性的影响,本文选用三种糯米样品,观测了其基本理化指标和粘度曲线等特性。测定浸泡(20℃~35℃)过程中糯米米粒水分含量的变化和最终的含水量,采用Peleg方程拟合糯米的吸水动力学特性,并对糯米浸泡前后红外光谱和X-射线衍射图谱的进行分析比较。研究发现越南米和长江米吸水量大,其最终含水量分别达到36.34%(20℃)和34.64%(28℃),温度对其影响较小;黑香米吸水速度和数量较小,最终含水量为31.99%(35℃),且温度对其影响较大;其次,可运用Peleg方程米对浸泡过程中糯米的近似水分含量进行预测。浸泡前后糯米的红外光谱在1047cm-1与1022cm-1峰的强度比值在0.89~0.92之间,无显著差异。X-射线衍射表明水分子主要进入糯米颗粒内的无定型区和亚结晶区,越南米和长江米样品的亚结晶区变小,黑香米则有所增大。本文研究可为米粉的加工提供理论指导。

Comparison of Physicochenical Properties of Soaked Glutinous Rice from Different Varieties

In order to study the effect of soaking treatment on the physicochemical properties of rice, three types of rice were selected, and their physicochemical properties and viscosity curve were investigated. Changes of moisture content and the final water content of rice during soaking(20 ℃~35 ℃) were measured, and the Peleg equation was used to fit the measured water absorption data. Infrared spectrum and X-ray diffraction were used to study the change of order structure and crystalline structure of rice before and after soaking. The study found that the Vietnamese rice and Yangtze River rice had greater water absorption, and the final water content reached 36.34%(20 ℃) and 34.64%(28 ℃), respectively, and temperature had little effect on it. Black fragrant rice had a small water absorption rate and water absorption, and its final water content reached 31.99%(35 ℃) and temperature had greater influence on it. In addition, the Peleg equation can be used to predict the approximate moisture content of rice during soaking. The ratios of the absorbance of the bands at 1047 cm-1 and 1022 cm-1 of rice before and after soaking was between 0.89 and 0.92, which was no significant difference. X-ray diffraction showed that water molecules mainly enter the amorphous region and the sub-crystalline region of rice, and the sub-crystalline region of the Vietnamese rice and Yangtze River rice became smaller, while that of the black fragrant rice was increased. This research can provide guidance for the processing of rice flour.