Study on the heat pump technology of Shuanghua-Plum preserved

In this paper, the technological parameters of heat pump drying for sugar preserved Shuanghua Plum were evaluated by testing drying rate and the moisture content, color and texture of the products compared with the traditional natural drying and hot air drying technology.Results showed that drying temperature had the greatest influence on the drying rate of heat pump drying, followed by relative humidity and tile density respectively, while all these parameters affected the texture and color of the products significantly. The optimal parameters of the heat pump drying technology were as follows: drying temperature49 ℃, relative humidity 30%, tile density 0.75 g/cm². Under these conditions, the time for drying the products to moisture content of 23.89% was only 8 h, and the products exhibited favorable appearance, color and texture.Comparing with the traditional natural drying technology and hot air drying technology, the time was reduced by 66.67% and 30.43% for the processing of heat pump drying technology.Besides, the resulted products were inferior to the heat pump drying products in hardness, elasticity and chewiness with serious browning and poor color.Compared with the traditional drying technology, heat pump drying was an ideal drying technology for preserved fruits due to its shorted drying time and resulting products with good quality.