Optimization of hot air drying process for cultivating Fritillaria thunbergii using response surface methodology
Fritillaria cirrhosa D. Don is one of the fundamental components of the traditional Chinese medicine Fritillaria cirrhosa, also known as rolled leaf Fritillaria. It is included in the 2020 edition of the Pharmacopoeia of the People’s Republic of China (hereinafter referred to as the “Chinese Pharmacopoeia”) and has the effects of clearing heat, moistening the lungs, resolving phlegm, stopping cough, dispersing nodules, and eliminating abscesses. At present, the processing method of Fritillaria thunbergii medicinal materials is still relatively traditional and not suitable for the industrial development of cultivating Fritillaria thunbergii. The research group compared the advantages and disadvantages of traditional sun drying and three modern drying methods in terms of appearance and internal quality in the early stage, and found that the hot air drying method can be widely used in the production and processing of cultivated Fritillaria thunbergii. This method can better maintain the appearance of the medicinal materials, reduce the loss of effective ingredients, and save time and cost for large-scale production of cultivated Fritillaria thunbergii. However, it was also observed that the appearance of the medicinal materials obtained by hot air drying is easily affected by temperature changes, so further optimization of the hot air drying process is needed.
At present, there is no unified and scientific origin processing standard for Fritillaria thunbergii medicinal materials. Blind and arbitrary drying processes can lead to inconsistent quality of Fritillaria thunbergii medicinal materials. Segmented variable temperature drying can shorten drying time, improve drying rate, and enhance drying quality. It has been applied in traditional Chinese medicinal materials and food industries such as American ginseng and Taizi ginseng. The preliminary experiment of the research group found that the surface color of the medicinal materials obtained by intermittent two-stage drying was relatively white, with less wrinkling and roughness, and the appearance was greatly improved compared to constant temperature drying. Therefore, this article further optimizes the hot air drying process for cultivating Fritillaria thunbergii, using response surface methodology to design and optimize the optimal segmented hot air drying process. At the same time, the effects of constant temperature drying and segmented variable temperature drying on the cultivation of Fritillaria thunbergii medicinal materials are compared, in order to provide reference for its standardized processing in production areas.

 

 

At present, wild Sichuan Fritillaria medicinal materials are mainly available in the market. However, due to excessive harvesting, low germination rate of seeds in natural environments, and harsh growth conditions, wild resources are decreasing day by day. Artificial cultivation has emerged, and the shape variation of cultivated products has become a common but still unsolvable problem. High quality appearance and internal quality are crucial for the use of Sichuan Fritillaria medicinal materials and will also affect their economic value. At the same time, if the processing in the production area is improper, the medicinal materials are prone to gelatinization, discoloration and other phenomena, which seriously affect the characteristics of Fritillaria thunbergii and lead to difficulties in selling the medicinal materials. The medicinal herb of Fritillaria thunbergii mainly contains alkaloids, nucleosides, and starch. The research team found in previous experiments that the higher the content of extract, the worse the properties of Fritillaria thunbergii. Therefore, the extract was not used as an indicator for this experiment. Instead, the quality of Fritillaria thunbergii was comprehensively evaluated by normalizing the properties of the medicinal herb, starch, total alkaloids, and total nucleoside content.

There are currently many literature reports on the processing technology of Fritillaria medicinal materials, and some studies have optimized the ordinary drying method, such as using UV drying, superheated steam, hot air microwave combined drying techniques, and adopting variable temperature and combined drying methods to improve the processing technology of Fritillaria medicinal materials. However, there is no relevant research on whether these methods are applicable to Fritillaria medicinal materials, and the involvement of combined equipment will also increase the production cost of medicinal materials. The processing method of Fritillaria thunbergii in the production area is still mainly based on constant temperature drying, but the drying temperature and time reported in the literature are different. Based on this, the research team conducted experimental research in the early stage, and the experimental results showed that the appearance and internal quality of the medicinal materials were better when dried at a constant temperature of 50 ℃. This article continues to further screen the hot air drying process of Fritillaria thunbergii medicinal materials, using three factors: the first stage drying temperature (X1), the moisture conversion point (X2), and the second stage drying temperature (X3). Three factor three-level response surface experiments were conducted, and the optimal two-stage drying process was obtained: drying at 60 ℃ to a moisture content of 45%, taking out and placing for 12 hours, and drying at 50 ℃ to a moisture content of ≤ 15.0%. After verification and comparison with the constant temperature drying of medicinal materials at 40-60 ℃, the two-stage drying method produces medicinal materials with white color and better quality. At the same time, it reduces the drying time of cultivated Fritillaria thunbergii medicinal materials, saves processing costs, and preserves the internal components to a large extent.

Through the design and optimization of response surface methodology, this study further investigates the hot air drying process for cultivating Fritillaria cirrhosa, expands the processing methods of Fritillaria cirrhosa medicinal materials, and provides data support for its standardized, large-scale, and standardized production. There are studies showing significant differences in drying time among different sizes of Sichuan Fritillaria. Therefore, it remains to be studied whether establishing corresponding two-stage drying methods for large, medium, and small sizes of Sichuan Fritillaria fresh products can save more processing costs.