Spray drying technology is one of the most commonly used unit operations in the production of traditional Chinese medicine(TCM) preparations, offering advantages such as short drying time and uniform product quality. However, due to the properties of TCM extracts, such as high viscosity, strong hygroscopicity, and poor flowability, there is limited scope to solve the problems of wall adhesion and clumping in spray drying from the macroscopic perspective of pharmaceutical production. Therefore, it has become a trend to study and optimize the spray drying process from the microscopic point of view by investigating single droplet evaporation behavior. Based on the reaction engineering approach(REA), the single droplet drying system, as a novel method for studying droplets, collects parameter data on individual TCM droplets during the drying process and uses the REA to process the data and establish predictive models. This approach is crucial for understanding the mechanism of TCM spray drying. This paper summarized and analyzed the cha-racteristics of various single droplet systems, the application of REA in single droplet drying systems, and its significance in optimizing the process, predicting drying states, and shortening the development cycle in the field of TCM spray drying, and looked ahead to the prospects of this method, including the introduction of new parameters and imaging techniques, aiming to provide a reference for further research in the field of TCM spray drying.
Medicine, Chinese Traditional ; Spray Drying ; Desiccation/methods* ; Temperature ; Technology

With the rapid development of computer technology, numerical simulation has gradually become an important method to study drying process and improve drying equipment. Using computer to simulate the drying process of traditional Chinese medicine(TCM) is characterized by intuitiveness, scientificity, and low cost, which serves as an auxiliary means for technical innovation in TCM drying. This paper summarizes the theories of different drying methods and the research status of numerical simulation in drying, introduces the modeling methods and software of numerical simulation, and expounds the significance of numerical simulation modeling in shortening the research and development cycle, improving drying equipment, and optimizing drying parameters. However, the current numerical simulation method for drying process has problems, such as low accuracy, lack of quantitative indicators for the control of simulation results on the process, and insufficient in-depth research on the mechanism of drug quality changes. Furthermore, this paper put forward the application prospect of numerical simulation in TCM drying, providing reference for the further study of numerical simulation in this field.
Medicine, Chinese Traditional ; Drugs, Chinese Herbal ; Desiccation

The present study explored the effect of co-amorphous technology in improving the dissolution rate and stability of silybin based on the puerarin-silybin co-amorphous system prepared by the spray-drying method. Solid-state characterization was carried out by powder X-ray diffraction(PXRD), polarizing microscopy(PLM), Fourier transform infrared spectroscopy(FT-IR), differential scanning calorimetry(DSC), etc. Saturated powder dissolution, intrinsic dissolution rate, moisture absorption, and stability were further investigated. The results showed that puerarin and silybin formed a co-amorphous system at a single glass transition temperature which was higher than that of any crude drug. The intrinsic dissolution rate and supersaturated powder dissolution of silybin in the co-amorphous system were higher than those of the crude drug and amorphous system. The co-amorphous system kept stable for as long as three months under the condition of 40 ℃, 75% relative humidity, which was longer than that of the single amorphous silybin. Therefore, the co-amorphous technology could significantly improve the dissolution and stability of silybin.
Calorimetry, Differential Scanning ; Desiccation ; Drug Compounding/methods* ; Drug Stability ; Silybin ; Solubility ; Spectroscopy, Fourier Transform Infrared ; Technology ; X-Ray Diffraction

The volatile oil of Chuanxiong Rhizoma(CX) is known as an effective fraction. In order to seek a suitable method for processing CX and its decoction pieces, this study selected 16 volatile components as indices to investigate how different processing methods such as washing/without washing, sun-drying, baking, oven-drying and far-infrared drying at different temperatures affected the quality of CX and its decoction pieces(fresh CX was partially dried, cut into pieces, and then dried) by headspace gas chromatography-mass spectrometry(GC-MS), cluster analysis, principal component analysis and comprehensive weighted scoring. The results showed that the rapid washing before processing did not deteriorate the volatile components of CX. Considering the practical condition of production area, oven-drying was believed to be more suitable than sun-drying, baking, and far-infrared drying. The CX decoction pieces with a thickness of 0.3-0.4 cm were recommended to be oven-dried at 50 ℃. The integrated processing(partial drying, cutting into pieces, and drying) did not cause a significant loss of volatile components. For the fresh CX, the oven-drying at 60 ℃ is preferred. The temperature should not exceed 60 ℃, and drying below 60 ℃ will prolong the processing time, which will produce an unfavorable effect on volatile components. This study has provided the scientific evidence for field processing of CX, which is conducive to realizing the normalization and standardization of CX processing in the production area and stabilizing the quality of CX and its decoction pieces.
Desiccation ; Gas Chromatography-Mass Spectrometry/methods* ; Oils, Volatile ; Principal Component Analysis ; Rhizome/chemistry* ; Volatile Organic Compounds/analysis*

The present study explored the drying effect of new spiral vibration drying technology on Chinese medicinal pills with Liuwei Dihuang Pills, Zhuanggu Guanjie Pills, and Muxiang Shunqi Pills as model drugs. With the drying uniformity, drying time, energy consumption, pill split, dissolution time, and change of index components as evaluation indicators, the drying effect of spiral vibration drying technology on model drugs was evaluated and compared with traditional drying methods, such as hot air drying and vacuum drying in the oven. The dynamic changes of moisture in Liuwei Dihuang Pills with different drying time were investigated. Compared with the traditional drying methods in the oven(hot air drying and vacuum drying) at 80 ℃, the spiral vibration drying only took 80 min, shortened by 80%, with 10%-13% energy consumed. The results showed that the moisture of Liuwei Dihuang Pills was negatively related to the drying time. By virtue of multi-layer countercurrent drying and super resonant fluidization techniques, the new spiral vibration drying technology can significantly improve the drying quality of Chinese medicinal pills, improve the drying efficiency, and enhance the manufacturing capacity of Chinese medicinal pills. This study is expected to provide references for the innovation and development of new drying technology of Chinese medicinal pills.
China ; Desiccation ; Physical Therapy Modalities ; Technology ; Vibration

Drying is one of the most common unit operations in the production of traditional Chinese medicine. The drying process of traditional Chinese medicine materials is accompanied by the dynamic reduction of water content. As a key index to determine the end of the drying process, the moisture content of materials plays an important role in improving drying efficiency and saving energy. Recently, the drying process of traditional Chinese medicine is mostly monitored by offline detection, and there are few reports of online moisture detection applications. In this paper, the principle and current application of online inspection technology for the material drying process in different fields were introduced. The significance of online detection technology in drying of traditional Chinese medicine was also analyzed. Meanwhile, the application prospect of online detection technology in the field of drying of traditional Chinese medicine was predicted. In response to urgent transformation and upgrading of the traditional Chinese medicine manufacturing industry, the application of online moisture detection technology is expected to be a key breakthrough in the intelligent upgrading of traditional Chinese medicine drying technology and equipment.
Desiccation ; Drugs, Chinese Herbal ; Medicine, Chinese Traditional ; Quality Control ; Technology, Pharmaceutical

In order to explore the effect of different drying methods(drying-in-the-shade, sun-drying, and hot air drying) on appearance characteristics, internal structure and composition of Belamcandae Rhizoma, so as to provide a theoretical basis for screening out suitable drying methods for primary processing. In this study, the Belamcandae Rhizoma's dynamic changes of the moisture content ratio and drying rate with different drying time under different drying methods, as well as the effects of different drying methods on the appearance, drying rate, density, ash, extractives and the contents of six flavonoids(mangiferin, tectoridin, iridin, tectorigenin, irigenin, irisflorentin) were compared. The results showed that fresh Belamcandae Rhizoma consumed the longest time to reach the water balance point by traditional dry drying in the shade, whiche was about 311 h; that by sun drying was 19.3%, which was shorter than drying in the shade; both drying curves were smoother. The section color of the sun drying samples was the closest to that of fresh samples, but the interior is full of holes, with a low density and loose structure. Hot air drying(40, 60, 80 ℃) could save about 27% to 88% of the drying time, which was greatly shorter, with less pores, a larger density and compact structure. Compared with the traditional drying method, the drying rate of hot air drying was reduced by 13.7%. Ash was affected by temperature, the drying conditions under 40 ℃ and below were not significantly different from those of conventional drying. The ash content decreased by 7.73% to 18.5% compared with conventional drying at 60,80 ℃. After conventional drying and 40 ℃ hot air drying, the contents of tectoridin and iridin(glycosides) in the samples were significantly higher than those in 60,80 ℃ hot air drying, while the contents of tectorigenin, irigenin and irisflorentin(aglycones) dried at 60 ℃ were the best. Therefore, considering comprehensive appearance characteristics and content of medicinal ingredients, traditional Chinese medicinal materials after 60 ℃ hot air drying show a solid texture, tight internal structure, good appearance, appropriate reduction of toxic parasides and higher aglycone content.
Desiccation ; Drugs, Chinese Herbal ; Rhizome

There is no consensus on the content, accumulation, transformation and content determination methods of phenolic acids in fresh Salvia miltiorrhiza. In order to find out the true content of phenolic acids in fresh S. miltiorrhiza, a variety of treatment me-thods were used in this study to prepare sample solution. The content changes of phenolic acids in S. miltiorrhiza samples with different dehydration rates were investigated during drying and shade drying processes. Polyphenol oxidase(PPO) of S. miltiorrhiza was extracted and purified by ammonium sulfate precipitation and dialysis to investigate the enzymatic properties. The content of rosmarinic acid, lithosperic acid and S. nolic acid B in S. miltiorrhiza was determined by UPLC. The results showed that the content of phenolic acids in fresh S. miltiorrhiza was highest when it was homogenized with 1 mol·L~(-1) HCl solution or 1 mol·L~(-1) HCl methanol solution. There was no significant difference in the content of phenolic acids in S. miltiorrhiza with different dehydration rates, indicating that there was no correlation between phenolic acid content and dehydration rate. The optimum pH of S. miltiorrhiza PPO was 7.6 and the optimum temperature was 40 ℃. With catechol as substrate, S. miltiorrhiza PPO had the enzymatic browning reaction which was in compliance with Michaelis equation, with Michaelis constant K_m of 0.12 mol·L~(-1) and V_(max) of 588.23 U·min~(-1). The inhibitory effect of citric acid, disodium ethylenediamine tetraacetate, ascorbic acid and sodium sulfite on S. miltiorrhiza PPO increased with the increase of inhibitor concentration, and sodium sulfite showed the strongest inhibitory effect. The present study proved that there were a large number of phenolic acids in fresh S. miltiorrhiza, which were the secondary metabolite of primitive accumulation during the growth of S. miltiorrhiza, rather than the induced product of postharvest drying and dehydration stress. This study has reference value and significance for the cultivation, harvest and processing of S. miltiorrhiza.
Catechol Oxidase ; Desiccation ; Hydroxybenzoates ; Plant Roots ; Salvia miltiorrhiza

To improve the spray drying effect of extract of Wenjing Zhitong Prescription, this study takes the yield, hygroscopic property and the fluidity of dry powder as indexes to screen out auxiliary materials, and the proportion of the auxiliary materials was optimized based on the mixing design experiment; based on that, HPLC method was established for the determination of glycyrrhizin and 6-gingerol in spray powder, the yield of spray powder and the retention rate of the two index components were taken as indexes to further optimize the spray drying parameters. The finally selected auxiliary materials were light magnesium oxide, maltodextrin and silica, and regression equations of dry powder yield, moisture absorption rate, angle of rest with proportion of auxiliary materials were established, and the optimized proportion of auxiliary materials was dry paste-light magnesium oxide-maltodextrin-silica=0.5∶0.305∶0.145∶0.05; according to the optimized drying process parameters of Wenjing Zhitong Prescription, initial temperature was 60 ℃, air inlet temperature was 130 ℃, air flow rate was 35 m~3·h~(-1), atomizing pressure was 40 mm, and liquid inlet speed was 4.5 mL·min~(-1). Under these conditions, the dry powder yield was 90.28%, the retention rate of glycyrrhizin was 74.51%, and the retention rate of 6-gingerol was 72.10%. In this study, optimized auxiliary materials can improve the yield of spray drying and the property of spray powder, and the optimized processing conditions were good for retaining the unstable gingerol components, which can lay a foundation for the further preparation research of meridian warming and pain relieving prescriptions, and provide reference for extract of other traditional Chinese medicine extracts that are difficult to spray drying.
Chemistry, Pharmaceutical/methods* ; Desiccation/methods* ; Drugs, Chinese Herbal/chemistry* ; Hot Temperature ; Medicine, Chinese Traditional ; Powders

There were significant differences in phenolic acid content between fresh and dried Salvia miltiorrhiza before and after drying. That is to say, the content of phenolic acid in S. miltiorrhiza significantly increased with the increase of dehydration during the drying process.In order to investigate the differences and transformation of free and bound phenolic acids before and after the drying process of S.miltiorrhiza, we studied hydrolysis method, hydrolysates and hydrolysis regularity of phenolic acids in S.miltiorrhiza. UPLC method was used to determine four main hydrolysates of bound phenolic acids, namely danshensu, caffeic acid dimer(SMND-309), caffeic acid, przewalskinic acid A(prolithosperic acid), and three main free phenolic acids in S.miltiorrhiza, namely rosmarinic acid, lithospermic acid, salvianolic acid B. The results of the acid-base hydrolysis experiment of salvianolic acid showed that the alkaline hydrolysis effect was significantly better than acid hydrolysis. The optimal alkaline hydrolysis condition was hydrolysis at 70 ℃ for 4 h with 2 mol·L~(-1) NaOH solution containing 1% ascorbic acid(Vit C). The hydrolysates of free phenolic acids were the same with the hydrolysates of bound phenolic acids. Fresh S.miltiorrhiza contains a low level of free phenolic acids and a high level of bound phenolic acids, which were exactly opposite to dried S.miltiorrhiza. It was suggested that a large amount of bound phenolic acids was accumulated during the growth of S.miltiorrhiza. These bound phenolic acids were coupled with polysaccharides on the cytoderm through ester bonds to form insoluble phenolic acids, which was not easy to be detected by conventional methods. However, during drying and dehydration processes, the bound phenolic acids were converted to a large amount of free phenolic acids under the action of the relevant enzyme.
Desiccation ; Hydroxybenzoates/analysis* ; Salvia miltiorrhiza/chemistry*