为优化微波-热风联合干燥大蒜粒的最佳工艺参数,以大蒜粒为试材,以干燥速率、大蒜素含量、感官评分、白度、复水比和综合得分为指标,比较研究不同微波功率密度、不同热风温度对大蒜粒干燥特性和品质的影响,并以微波功率密度、转换点干基水分含量、热风温度为试验因素,设计L9(33)正交试验对微波-热风联合干燥大蒜粒的工艺条件进行优化。结果表明,9.2 W/g微波干燥和70 ℃热风干燥所得大蒜粒干品的综合得分最高,分别为94.698、96.566。微波功率密度对联合干燥大蒜粒的综合得分影响极显著(p＜0.01);转换点干基水分含量和热风干燥温度对综合得分无显著影响(p＞0.05)。微波-热风联合干燥大蒜粒的最佳工艺条件为先期采用功率密度9.2 W/g微波干燥至转换点(干基水分含量1.200 g/g),后期用热风60 ℃干燥至干基含水量0.100 g/g;在此条件下,联合干燥所得大蒜粒的大蒜素、复水比、白度、感官评分分别为0.956 mg/g、2.699、83.130、83.000,干品综合得分为125.281。因此,微波-热风联合干燥是适合大蒜粒干燥的较好技术方法。
This study aimed to find the optimum conditions of garlic drying by microwave and hot air combination. The influence factors of microwave power density and hot air temperature were investigated using the drying rate, allicin content, sensory quality, whiteness, rehydration ratio and comprehensive scores were chosen as indexes. The combined drying conditions were optimized through L9 (33) orthogonal test with microwave power density, moisture content of conversion point and hot air temperature as experimental factors. The results showed that the comprehensive scores of garlic dried under microwave power at 9.2 W/g and hot air at 70 ℃ were 94.698 and 96.566, respectively. The overall score of garlic was significantly influenced by microwave power density (p＜0.01) but not significantly influenced by the conversion point of moisture content and hot air temperature (p＞0.05). The optimum conditions of combined microwave and hot air drying were 9.2 W/g microwave to 1.200 g/g moisture content of conversion point, then 60 ℃ hot air drying to 0.100 g/g moisture content. Under these optimum conditions, the content of allicin, rehydration ratio, whiteness, sensory evaluation and comprehensive score were 0.956 mg/g, 2.699, 83.130, 83.000 and 125.281, respectively. Therefore, microwave drying followed by hot air drying was a better method and quite suitable for garlic drying.
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