ABSTRACT
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.