湿法制粉工艺对糯米粉淀粉损伤及糊化特性的影响

EFFECT OF WET-MILLING PROCESS ON DAMAGED STARCH CONTENT AND GELATINIZATION PROPERTIES OF GLUTINOUS RICE FLOUR

糯米粉加工制粉过程中不可避免产生破损淀粉,从而对其加工特性产生影响。为改进糯米粉加工工艺,研究了湿法加工过程中浸泡时间、浸泡液种类、浸泡温度、研磨次数及干燥温度等因素对制得的糯米粉的破损淀粉含量和糊化特性的影响,并对湿法制粉工艺、破损淀粉及糊化特性之间的相关性进行了分析。结果表明:浸泡时间为60 min时,破损淀粉含量下降至6.13%;柠檬酸和氢氧化钠浸泡液并未改善糯米粉特性,湿法加工糯米粉时可直接采用自来水浸泡;浸泡温度(小于45℃)为30℃时,破损淀粉含量下降至5.29%;增加研磨次数使糯米粉粒度变小,改善糯米粉品质,但研磨2次后品质改善不明显,反而会使破损淀粉含量增加;干燥温度对糯米粉糊化特性影响较大,主要表现为当干燥温度为50℃和60℃时,破损淀粉含量显著高于其他干燥温度下破损淀粉含量;不同制粉工艺对糯米粉糊化特性的影响不同。相关性分析表明:制粉条件与破损淀粉含量、糊化特性之间存在一定的相关性。其中:浸泡时间与峰值黏度、低谷黏度、衰减值、最终黏度、回生值均呈极显著相关(r=0.660,r=0.587,r=0.650,r=0.564,r=-0.587);浸泡液种类与低谷黏度、最终黏度呈显著相关(r=0.418,r=0.446),与峰值时间、糊化温度呈极显著相关(r=0.615,r=0.683);研磨次数与破损淀粉含量呈极显著相关(r=0.646)。综合考虑:自来水浸泡60 min、浸泡温度40℃,研磨次数1~2次,干燥温度40℃或者80℃时制得的糯米粉品质较好。

Damaged starch will be produced unavoidably in the milling process of glutinous rice,which will affect the processing quality of glutinous rice flour. In order to meet the needs of processing technology of glutinous rice flour,the effect of soaking time,soak solution,soak temperature,grinding times and drying temperature on the damaged starch content and pasting properties of glutinous rice flour prepared by wet-milling processing was investigated in the present study. The correlation in the wet milling process,damaged starch and the gelatinization characteristics were also analyzed. The results showed that: when the glutinous rice flour was soaked for 60 min,the content of damaged starch decreased to 6.13%,which was decreased to 5.29% with the immersion temperature(less than 45 ℃) of 30 ℃. Citric acid and sodium hydroxide solution did not improve the characteristics of glutinous rice flour,while tap water could be used as the soaking solution. With the increasing of the grinding times,the particle size of glutinous rice flour particle size became smaller and the quality was improved,but the improvement of the quality was not obvious and the damaged starch content increased after grinding for 2 times. Drying temperature had a great effect on gelatinization of glutinous rice flour.When drying temperature was 50 ℃ and 60 ℃,the content of damaged starch was significantly higher than that of other drying temperature. The effect of different milling conditions on gelatinization properties had significant difference. Correlations analysis showed that significant correlation existed in milling conditions,damaged starch and gelatinization properties. The results showed that the soaking time was significantly correlated with the peak viscosity,the trough viscosity,the decay value,the final viscosity and the regenerated value(r=0.660;r=0.587;r=0.650;r=0.564;r=-0.587). The soaking solution had a significant correlation with the viscosity,the final viscosity,the peak time and gelatinization temperature(r=0.418;r=0.446;r=0.615;r=0.683). And the grinding times also had a significant correlation with the damaged starch content( r=0.646). It was concluded that the better quality of glutinous rice flour was afforded with the conditions of water soaking for 120 min at 40 ~45 ℃,grinding for 1~2 times and drying at 40 ℃ or 80 ℃.