Optimization of carrot heat pump drying process by response surface methodology

Abstract

Objective: This study focuses on optimizing the heat pump drying process of carrot. Methods: On the basis of single factor experiment, Box-Behnken experiment was designed. Color difference, rehydration ratio and β-carotene content were used to study the effects of initial temperature, drying temperature rise and slice thickness on carrot drying quality. The regression equation was established, and the interaction between three independent factors on the response was analyzed. The optimal drying process parameters and the predicted values of carrot heat pump drying were obtained. Finally, the optimal parameters were determined by comparing the experimental results with the predicted values. Results: The optimal process parameters of carrot heat pump drying were as follows: the initial and drying temperature were 54.1 ℃ and 9.25 ℃ respectively, and the slice thickness was 3.8 mm. Under the control of these conditions, the color difference value of carrot was 9.759, the rehydration ratio was 6.196, with the content of β-carotene of 34.378 mg/100 g. The dried product was bright orange red, and the rehydration ratio and the retention of β-carotene were high. Conclusion: Response surface method can determine the best process parameters of carrot heat pump drying, and help to obtain the best quality of carrot dried products.

Keywords

• heat pump drying
• response surface method
• process optimization
• the color difference
• rehydration ratio
• carotenoids