Simultaneous Application of Vacuum and Infrared Drying to Whole Drying Process of Bitter Gourd Slices: Design, Drying Kinetics, Experiment, Characteristic, Energy Aspect

Abstract

HighlightsBitter gourd slices were dried using vacuum infrared coupling drying method.Increased drying rate and effective water diffusivity and greatly reduced energy consumption.Provided a theoretical reference for the drying of high quality agricultural products.Increased the added value of agricultural products.Abstract.To improve the processing rate and product quality of bitter gourd, a new type of vacuum infrared coupled drying method was proposed. The impact of drying temperature, vacuum, and thickness were investigated on the physicochemical features. The results showed that the moisture content was greatly affected by temperature change but less influenced by the change of vacuum degree. The thickness had little influence on the moisture content change when the slice thickness increased to a certain value about 6mm. The experiments revealed that the drying rate reached to the maximum when the slice thickness was 2 mm. The drying quality of bitter gourd slices could reach to the best smell, tissue state and color when the drying test was carried out at thickness 4 mm, vacuum 10 kPa, and temperature 55°C. Taking drying rate as evaluation index and temperature, thickness, and vacuum degree as influencing factors, a regression model of drying rate was established. Design-expert software was used to solve the optimal drying process conditions. The results showed that the drying rate was 26.47 g/(g.h) when temperature, thickness and vacuum degree were 56°C, 3 mm, and 11 kPa. Therefore, bitter gourd slices would be dried quickly and effectively by using the simultaneous technique of vacuum infrared drying method. Keywords: Bitter gourd slice, Drying quality, Moisture content, Vacuum infrared coupled drying.