EFFECT OF DRYING METHOD ON TOTAL PHENOLIC CONTENT AND ANTIOXIDANT ACTIVITY OF BLACK GINGER (KAEMPFERIA PARVIFLORA WALL. EX BAKER) SLICES IN DAK LAK, VIETNAM

By Hoang Nhat Phi, Pham Thi My Tram
DOI: 10.37550/tdmu.EJS/2025.04.690

The herbal plant known as black ginger (Kaempferia parviflora Wall. Ex Baker) is a member of the Zingiberaceae family and is extensively distributed in tropical and subtropical regions of Asia. Traditionally, black ginger is used as a health-enhancing herb to relieve joint pain, digestive disorders, and infections.
This study aimed to assess how drying method (sunlight, dried in an oven) affected the moisture content, total phenolic content, and antioxidant activity of slices of black ginger root and rhizome. Total phenolic content was measured using the UV-vis spectrophotometry method with a gallic acid standard. The DPPH free radical scavenging experiment was also used to assess the extracts' antioxidant potential.
Phytochemical screening results showed that black ginger rhizomes and roots had many secondary metabolites, such as alkaloids, flavonoids, polyphenols, and tannins. The highest total phenolic content was found in sliced black ginger rhizomes dried at 60°C (69.15 mg GAE/g extract). Moreover, black ginger samples all had relatively good antioxidant activities, with IC50 values 42.34 to 67.14 times higher than the IC50 of ascorbic acid. The investigation results on drying temperature's effects on TPCs, and the antioxidant activities of black ginger rhizomes and roots support knowledge and experience in using dried black ginger as raw materials for food and pharmaceutical industries.