流态化及缓苏干燥技术对泰国香稻的香味和磨粉品质的影响

Effects of Drying Using Fluidisation Technique with Tempering on Aroma and Milling Qualities of Khao Dawk Mali 105, Oryza sativa L.

将高温(>100℃)流态化干燥和缓苏相结合干燥泰国香稻(Khao Dawk Mali105,籼稻),使其湿含量降至13-14%(湿基),以便于安全贮存。研究了干燥与贮存过程对籼米香味和磨粉品质的影响。泰国香稻需要经过两个干燥阶段。第一阶段是在高温流化床中干燥,缓苏30分钟,然后返回高温流化床干燥或阴干,直至湿含量降低到安全贮存水平。实验结果表明,干燥温度对香稻的整精米率(HRY)、白度指数(WI)和2AP含量均有影响。多数干燥温度下整精米率的水平都比较低,但150℃除外,此情况下整精米率(p≤0.05)显著提高。然而,当一次流态化干燥和缓苏之后,以阴干代替二次流态化干燥,香稻的整精米率显著增加,尤其是在135℃和50℃时(p≤0.05)。在贮存期间,白度指数和2AP含量显著降低(p≤0.05),而整精米率保持不变。对比环境温度(28-30℃)和15℃贮存温度,结果表明保持香米2AP含量和白度指数的适宜保存温度是15℃。然而贮存条件对整精米率影响不大(p>0.05)。本研究将有益于泰国香米行业的发展,为泰国香米的干燥起到指导性作用。

A combination of high temperature fluidization （〉 100℃） and tempering is employed to dry Thai fragrant paddy （Khao Dawk Mali 105, Oryza sativa L.） to the safe storage level of moisture content at 13-14 % wb. The aroma and milling qualities are studied in relation to the effect of the drying process and storage period. Thai fragrant paddy is dried into two stages of drying. The first stage is high temperature using fluidized bed dryer, followed by tempering for 30 minutes and back to high temperature fluidized bed drying or shade drying until moisture content decreased to safe storage level. The results of the experiment show that after drying, drying temperatures have effects on Head Rice Yield （HRY）, White Index （WI） and 2AP content. Most of the drying temperatures used gave a low level of HRY except for 150~C, which led to a significant increase of head rice yield （p〈0.05）. However when the second ftuidization is replaced with shade drying after the first fluidization and tempering, HRY increases significantly, especially at 135 and 150~C （p〈0.05）. During storage, white index and 2AP content decrease significantly （p〈0.05） while HRY remained unchanged. When comparing between ambient temperature （28-30℃） and 15℃ storage condition, it is found that the suitable condition to maintain 2AP content and white index of fragrant rice is 15℃. However the storage condition does not significantly affect the HRY （p〉0.05）. The information obtained from this study will benefit the Thai fragrant rice industries, showing appropriate drying strategies for Thai fragrant rice.