Abstract:

This study aimed to improve the overall quality of honeysuckle dried by far-infrared assisted heat pump drying
by the optimization of operating parameters using response surface methodology. Heat pump drying temperature, converted
moisture content and radiant panel temperature were taken as independent variables, and the contents of chlorogenic acid,
mignonette glycosides and anthocyanins were taken as response variables. Results showed that the absolute values of error
between the experimental values of four responses and the prediction from the proposed regression model were lower than 6%.
After normalization, the optimal experimental conditions were obtained as follows: heat pump temperature, 39 ℃; converted
moisture content, 55%; and radiant panel temperature, 90 ℃. Under these conditions, the chlorogenic acid content was
4.086 0 mg/g, mignonette glucoside content was 0.090 57 mg/g, anthocyanins content was 0.116 1 mg/g, and browning
degree was 0.859 6. Compared with the heat pump drying method, the drying time of the method used in this study was
reduced by 52.1%, drying energy consumption was decreased by 59.8%, and water reabsorbing capacity was increased by
7.9%. Moreover, the contents of chlorogenic acid, mignonette glycosides and anthocyanins were increased by 3.3%, 0.6%
and 1.3% respectively, while the browning degree of honeysuckle was lowered by 4.1%.

Key words: honeysuckle, heat pump, far-infrared heating, combined dryer, quality control