Modeling and optimization of solar-assisted heat pump drying of pumpkin slice

Purpose To reduce energy consumption, the time needed of drying, and the loss of ß -carotene content, and ascorbic acid content, response surface methodology (RSM) was employed for optimization. Design/methodology/approach To reduce energy consumption, the time needed of drying, and the loss of ß -carotene content, and ascorbic acid content, response surface methodology (RSM) was employed for optimization. Findings The results show that the optimum solar-assisted heat pump drying (SAHPD) conditions for drying pumpkin slice were: drying temperature of 67.40 °C, loading density of 1.05 kg/m 3 , and material thickness of 4 mm. Under these conditions, slice of pumpkin were dried in 440.637 min, where the unit energy consumption, ascorbic acid content, and ß -carotene content were 16.737 kJ/g, 25.682 mg/ (100–g dried sample), and 10.202 mg/g, respectively. The structure of the samples dried using the optimized SAHPD method exhibited a more complete cell morphology than those dried using heat pump drying when examined using scanning electronic microscopy. Originality/value This suggests that the optimized SAHPD conditions used in this study are important for production and processing.