Drying Characteristics and Modeling of Vacuum Far-Infrared Radiation Drying of Flos Lonicerae

Abstract

Vacuum far-infrared radiation (VFIR) drying of Flos Lonicerae was conducted, and the far-infrared radiation heater's temperature and chamber's pressure level ranged from 90 to 130C and from 400 to 40,000 Pa, respectively. Drying characteristics of VFIR drying were studied, and the results showed that the drying time decreased with the increase of the heater's temperature and the decrease of pressure. Chlorogenic acid content of dried Flos Lonicerae increased with the decrease of pressure level, and had a peak value when the heater's temperature increased. A mathematical model was developed for predicting the moisture ratio of Flos Lonicerae undergoing VFIR drying, and the nonlinear regression technique was applied to determine model parameters n and k. Comparing with calculated and experimental values, the model shows quite good accuracy for the estimation of the moisture ratio of Flos Lonicerae during the VFIR drying process. Practical Applications The traditional method for Flos Lonicerae drying is hot-air drying, and there are some other drying ways for Flos Lonicerae such as microwave drying and vacuum drying. But there is no research on vacuum far-infrared radiation (VFIR) drying of Flos Lonicerae in existing literature. Comparing with hot-air drying or microwave drying, the effective component conservation ratio of VFIR drying of Flos Lonicerae is much better. A drying model including the parameters of heater's temperature and pressure level has been developed, which could predict moisture ratio in VFIR drying of Flos Lonicerae very well. Therefore, VFIR drying technology could be applied to produce Flos Lonicerae with high quality and could be developed for drying other agricultural products.