Abstract: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.