Microwave drying characteristics and drying model of sweet potato chips
Abstract: The characteristics of microwave drying equipment of potato chips were studied. The microwave drying test factors of potato chips were determined. The single factor test was carried out to analyze the loading, microwave power and slice thickness from the relationship between water content, water loss rate and power consumption. The effect of microwave drying characteristics of the potato chips on the microwave drying process of the potato chips was obtained. The mathematical model of microwave drying of potato chips was determined. The DPS software was used to fit the experimental data, and the fitting equation which accorded with the microwave drying law of the potato chips was obtained. The statistical test showed that the fitting effect was very good.
Key words: sweet potato microwave drying; characteristics; model
Sweet potato is one of the traditionally cultivated food crops. It is rich in nutrients and enjoys the reputation of “nutrition and health food”. China's sweet potato has the highest annual planting area and total output, ranking first in the world. However, due to its high water content, perishable and dehydrated sweet potato, it has become a short-lived and difficult-to-preserve agricultural product.
Compared with the traditional drying method, microwave drying not only has high heat utilization rate, short heating time, saves energy, saves production cost, and can improve the eating quality after grain drying, and the drying process is easy to automatically control. Therefore, microwave technology has broad application prospects in food drying. In this study, the drying characteristics and drying model of the sweet potato were studied by microwave drying, and the microwave drying law was mastered to provide a basis for the industrial production of microwave drying of sweet potato.
(1) The change of loading and emission power has a significant effect on the dehydration characteristics of microwave drying of potato chips, and the effect of slice thickness is not significant.
(2) When the drying conditions are the same, when drying to a safe moisture content, as the thickness of the slice increases, the dehydration rate decreases, the drying time increases, but the effect is small; the loading is doubled, and the drying time is Increased by 0.4 to 0.5 times; the power is doubled, and the drying time is reduced by 0.5 to 0.6 times.
(3) The water loss characteristic of microwave drying of potato chips can be expressed by Page equation: MR = exp(-KtN). The fitting equation of microwave drying of potato chips can be obtained by DPS software: ln(-lnMR)
= -6 .58487 +1 .10149P -0 .0928P2 +(1 .30069+0 .22358P -0 .05213P2)lnt , the statistical test shows that the fitting effect is very good.