Drying kinetics and quality characteristics of exocarpium citreic grandis slices with hot air, vacuum, and microwave vacuum dryers

Article type: Research Article

Authors: Li, Qiang^{b; c} | Pan, Xiaoli^{a; d; e; *} | Fan, Wenyan^{b; c} | Zhou, Ying^{b; c} | Liu, Yongfu^a | Yu, Wangxin^a | Li, Dongyu^{b; c} | Li, Wenyue^a | Li, Weibin^a

Affiliations: [a] School of Physical and Telecommunication Engineering, Yulin Normal University, Yulin, Guangxi, China | [b] Yulin Center for Food and Drug Control, Yulin, Guangxi, China | [c] Yulin Engineering Technology Research Center for Quality Detection and Evaluation of Chinese Medicinal Materials containing aromatic materials, Yulin, Guangxi, China | [d] Guangxi Colleges and Universities Key Lab of Complex System Optimization and Big Data Processing, Yulin Normal University, Yulin, Guangxi, China | [e] Center for Applied Mathematics of Guangxi, Yulin Normal University, Yulin, Guangxi, China

Correspondence: [*] Corresponding author: Xiaoli Pan, School of Physical and Telecommunication Engineering, Yulin Normal University, Jiaoyudong 1303, Yulin, Guangxi 537000, China. E-mail: 349230222@qq.com.

Abstract: The study investigates the impact of different drying methods on the selection of thin-layer drying kinetic models, parameters, and quality for Exocarpium Citreic Grandis. This study investigates the drying characteristics, index constituents content, and microscopic structures of Exocarpium Citreic Grandis slices, subjected to three drying techniques: HAD (at 50, 60, 70∘C), VD (at 50, 60, 70∘C), and MVD (at 1000, 1500, 2000W). A thin-layer drying kinetic model was established. The findings demonstrated that the drying process was primarily dominated by the falling rate phase. When the drying temperature was 70∘C and the microwave power was 2000W, the HAD VD, and MVD took 120, 360, and 20 minutes respectively. By fitting six commonly used thin-layer drying models, it was discovered that the optimal mathematical models for HAD, VD, and MVD were the Page model, the Logarithmic model, and the Page model, respectively. The highest average R2 values were 0.9963, 0.9965, and 0.9964, and the lowest average RMSE values were 0.01782, 0.01704, and 0.0174 respectively. The effective diffusion coefficient increased with the drying temperature and microwave power, with MVD having the maximum coefficient. As the temperature and microwave power increased, the contents of naringin and rhoifolin decreased. However, the naringin content in MVD was 23.05% and 45.71% higher compared to hot air and VD respectively. The cross-section of Exocarpium Citreic Grandis dried via microwave vacuum exhibited a porous honeycomb structure with uniformly distributed spaces and larger pores, reflecting an expansion effect. The HAD process also resulted in a honeycomb-like structure, but with smaller pores. The VD process resulted in a layered structure with significant cell collapse. Microwave vacuum drying demonstrates superior energy efficiency and product quality compared to hot air and vacuum drying methods. The study finds that microwave drying does not have a destructive impact on the active compounds of Exocarpium Citreic Grandis. To facilitate large-scale, continuous production, microwave drying can be practically applied in industrial processing.

Keywords: Exocarpium Citreic Grandis, microwave vacuum, hot air drying, vacuum drying, thin-layer drying model

DOI: 10.3233/JCM-247143

Journal: Journal of Computational Methods in Sciences and Engineering, vol. 24, no. 3, pp. 1363-1377, 2024