ABSTRACT
Objective: Taking Qiju Dihuang Pills (QDP) as the research object, time domain reflection method was used for real-time determination of moisture content in concentrated pills during drying process and optimization of the drying process parameters. Methods: The moisture model of the drying process of QDP was established by the relationship between the water, temperature, and the reflective signal value of time domain reflector. The effect of the drying process on the different thickness (8, 16, and 24 mm), different drying temperatures (30, 40, 50, 60, 70, 80, and 90℃) was investigated. Results: The moisture model of the drying process of QDP was measured by time domain reflection method as Y = 0.305 X-34.772 (r2 = 0.999); X = X(T)-(0.768 9 T-24.824 7) (T ≥ 30℃). The optimized process was as following: the process was dried at 60℃ to 13.8% moisture and then rising to 80℃, after being dried to 7.80%, cooled to 60℃ and dried to 5.0% target moisture. Conclusion: It is feasible to test the moisture content in the drying process of QDP by time domain reflection method. This method can be used to monitor and popularize the moisture content in the drying process of traditional Chinese medicine concentrated pills.