Different drying methods alter the quality parameters of ethnobotanically important Curcuma caesia Roxb. rhizomes

Abstract

Curcuma caesia Roxb. of the Zingiberaceae family, is an ethnobotanically important rhizomatous perennial herb and is commonly known as “Black turmeric”. Like in other species of Curcuma, the pharmacologically important polyphenol curcumin is also found in C. caesia. In traditional medicine, C. caesia has been used to treat piles, leprosy, asthma, cancer, diabetes, fertility, toothache, vomiting, allergies, etc. Drying is considered the simplest and most cost-effective means of preserving raw plant materials, safeguarding the integrity of nearly all biologically active substances. Medicinal plant materials are primarily utilized in their dried forms in pharmaceutical industries. However, it has been observed that there is a lack of comprehensive information on the effects of different drying methods on quality parameters, and other pharmaceutically important aspects of C. caesia. Hence, here, we investigated the impact of various drying methods, such as direct sunlight exposure, solar drying, shade drying, and conventional oven drying with or without previous boiling, on the quality parameters of C. caesia rhizome, such as moisture, ash, and curcumin content. The results suggest that oven drying at 100 ?C, despite possessing favorable criteria for drug designing like the smallest particle sizes and the lowest moisture content, did not restore the maximum level of ash, curcumin, and essential mineral elements. Nevertheless, boiling in the range of 60 ?C – 80 ?C for 30 minutes before drying restores the pharmaceutically important qualities more favorably. The results of this study will help to formulate better treatment for restoring the market-preferable optimum quality of C. caesia.