Abstract
Exploring new drying technology can help to deal with the challenge of better preservation of rhizome medicinal materials in the traditional Chinese medicine industry. In current work, combined infrared and hot-air drying (IR-HAD) was employed to Panax notoginseng roots and its effect on drying kinetics, energy efficiency and quality, i.e., rehydration ratio (RR), color parameters (L*, a*, b*), total color difference (∆E), Panax notoginseng saponins (PNS) content, and ginsenosides content (R1, Rg1, Re, Rd, Rb1) were evaluated. Hot air drying (HAD) was used as the control. Results showed that the increase in drying temperature significantly shortened drying time and reduced energy consumption. The shortest drying time of 43.0 h and lowest specific energy consumption of 15.9 kW·h/(kg-water) were obtained by IR-HAD at 55°C. The decrease of radiation distance and the increase of radiation power led to the shortening of drying time. However, high drying temperature resulted in large ΔE values, large collapse structure, and RR of samples. The drying time of Panax notoginseng roots dried by IR-HAD at a drying temperature of 50°C was shorter (15.5%) than HAD dried at the same drying temperature. The contents of R1, Rg1, Re, Rb1, and PNS were higher when the samples were dried by IR-HAD than those dried by HAD at the same temperature of 50°C. Moreover, the IR-HAD dried samples shortened 15.5% drying time and saved 22.1% energy consumption compared with HAD. Therefore, the optimal process condition was Panax notoginseng roots under IR-HAD at drying temperature of 50°C, radiation distance of 12 cm and radiation power of 1350 W, which can shorten drying time, maintain high ginsenosides contents and satisfactory apparent qualities. Keywords: Panax notoginseng (Burk.) F. H. Chen (Araliaceae) roots, infrared and hot air drying, drying kinetics, energy consumption, quality DOI: 10.25165/j.ijabe.20221501.6210 Citation: Jiang D L, Zheng Z A. Effects of combined infrared and hot-air drying on ginsenosides and drying characteristics of Panax notoginseng (Araliaceae) roots. Int J Agric & Biol Eng, 2022; 15(1): 267–276.
Highlights
The drying time of Panax notoginseng roots dried by infrared and hot-air drying (IR-Hot air drying (HAD)) at a drying temperature of 50°C was shorter (15.5%) than HAD dried at the same drying temperature
The contents of R1, Rg1, Re, Rb1, and Panax notoginseng saponins (PNS) were higher when the samples were dried by infrared and hot-air drying (IR-HAD) than those dried by HAD at the same temperature of 50°C
The contents of Rg1, Re, Rb1, and PNS were higher when the samples were dried by IR-HAD at 50°C and radiation distance of 12 cm and radiation power of 1350 W than the fresh samples
Summary
H. Chen roots are the perennial herbs of the genus Araliaceae, which is one of the commonly used as a medicine called Xueshuantong due to its saponin constituents[1]. The total planting area of Panax notoginseng in Yunnan Province, China was over 3000 hm in 2020[2]. Panax notoginseng roots were rich in nutrients, containing saponins (PNS), polysaccharides, dencichine, amino acids, flavonoids, phytosterols, cyclopeptides, saccharides, fatty acids, volatile oils, aliphatic acetylene hydrocarbons, and trace elements[3-6]. PNS are the main active compounds of Panax notoginseng, and more than 100 PNS have been isolated and identified, including ginsenosides, notoginsenosides, and gypenosides. I.e., ginsenoside Rb1, ginsenoside Rg1, notoginsenoside R1, ginsenoside Rd and ginsenoside Re, are most often used in pharmacy and medicine[7]. Ginsenoside R1 is an important component of Xueshuantong capsule[8]. In recent years, dried roots were used as a raw material in the manufacture of health products, such as Panax notoginseng tea and Panax notoginseng wine[9]
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