热泵温度对白萝卜干燥速率及品质的影响

分别以热泵温度50,55,60,65℃对白萝卜进行干燥,比较不同热泵温度下的白萝卜干燥速率、色泽、营养成分、复水率、微观组织结构等。结果表明:热泵温度50,55,60,65℃下,白萝卜含水量降至(8±1)%分别需12,11,10,9h;热泵温度55,60℃对白萝卜色泽保持较好;影响白萝卜干复水率的热泵温度依次为55℃>60℃>50℃>65℃,其中55,60℃下差异不显著(P>0.05);白萝卜干总糖、蛋白质和VC含量以热泵温度50℃干燥的较高,且随热泵温度的升高而降低;而热泵温度过低或过高都会对产品品质产生不利影响。综合考虑,热泵温度55℃可作为白萝卜热泵干燥的最佳干燥温度,此条件下获得的白萝卜干具有最佳的综合品质。

Effect of different heat pump temperatures on drying rate and quality of white radish

In order to explore the effects of different heat pump temperatures on the drying rate and quality of white radish during drying,heat pumps at 50,55,60,65 ℃ were designed to dry white radish.The drying rate,color,nutrition,rehydration ratio and micro-structure of white radish at different heat pump temperatures were compared.The results showed that the moisture content of white radish decreased to(8±1)% at 50,55,60,65℃ heat pump temperatures,which required 12,11,10,9 hours respectively.Hot air drying at different temperatures had certain effects on the physical and chemical properties of white radish.The color of white radish was maintained well by heat pump drying at 55 ℃ and 60 ℃.The rehydration ratio of white radish was 55℃,60℃,50℃,65 ℃from large to small,and the difference between 55 ℃ and 60 ℃ was not significant.The total sugar,protein and vitamin C content of dried radish was higher by heat pump drying at 50 ℃,and increased with the increase of temperature.In general,too low or too high temperature of heat pump will adversely affect the quality of products.Considering the product quality,energy consumption and drying time,it is considered that 55 ℃ is the best drying temperature for heat pump drying of radish,and the dried radish obtained at this temperature has the best comprehensive quality.