摘要:
为了探讨微波干燥荔枝整果的热质变化机理,揭示干燥过程中荔枝的物理变化过程。基于荔枝的干燥速率、能量消耗、温差梯度、褐变情况和果肉收缩度的变化,分析了微波间歇干燥荔枝鲜果至半干型荔枝干过程中的物理变化过程,证明了采用微波间歇干燥工艺干燥整果荔枝具有快速干燥、半干型荔枝干果肉质量均匀、低能耗、设备工艺简单的优点。实验表明在综合能耗、色泽和收缩度的条件下,700W微波输出功率下7s/65s加热间歇时间为最佳工艺,能耗为2.11,荔枝干呈现均匀金黄色,L*、a*、b*值分别为37.5、14.4和16.4,果肉收缩度遵循近线性膨胀/收缩,果皮表面无明显凹陷。实验研究为半干型荔枝干选择适宜的微波干燥方式和研究微波干燥中荔枝的水分和温度变化的计算机仿真模型提供了参考。
关键词:
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荔枝
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微波干燥
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间歇干燥
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物理变化
Abstract:
The objective of this study was to discuss the mechanism of heat and mass change on whole litch and evaluate the physical changes in microwave drying. Based on the analysis of the drying rate of litchi,energy consumption,temperature gradient,browning and pulp shrinkage,physical changes on drying litchi process and corresponding mechanism was studied and discussed in this paper. This study proved that the intermittent drying technology of microwave drying on whole litchi had the advantages of fast drying,high semi-dried litchi pulp quality advantages,low energy consumption,simple device and process. Experiments showed that considering the comprehensive physical changes including energy consumption,color,shrinkage,hardness and texture conditions,microwave power 700 W 7s/65 s heating interval time was the best technology.Meantime,energy consumption was 2.11,and litchi pulp had uniform gold color,in which L*,a*,b* values were separately 37.5,14.4 and 16.4. With flash shrinkage coefficient followed nearly linear shrinkage expansion/contraction,no obvious depression disappeared on surface. Meanwhile,it also helpd choosing proper microwave drying method,and gave reference to the establishment of the computer simulation model of microwave drying of litchi moisture and temperature change.