Effect of drying conditions on quality and bioactive properties of Black ginger bag tea (Distichochlamys orlowii)

Abstract

Black ginger (Distichochlamys orlowii) is a valuable medicinal plant rich in bioactive compounds, exhibiting various health-promoting effects, including antioxidant, anti-inflammatory, antimicrobial, anticancer, and immune-enhancing properties. However, these bioactive compounds are significantly affected by heat during the drying process. This study aimed to evaluate the effects of drying conditions (temperature and time) on the physicochemical, biochemical, and sensory quality of Black ginger bag tea, thereby determining the optimal drying parameters that minimise the loss of bioactive compounds in the final product. Drying experiments were conducted at temperatures ranging from 40 to 60 °C, with the drying times varying from 7 to 11 hours. After drying, the samples were analysed for total soluble solids, reducing sugars, total polyphenols, antioxidant capacity (DPPH – IC₅₀), and sensory attributes. The results indicated that drying at 50 °C for 9 hours produced the highest overall quality, with a safe moisture content of 6.15%, total soluble solids 15.61%, reducing sugars 2.62%, total polyphenols 3.06 mg GAE/g dry weight, and the highest antioxidant capacity (IC₅₀ = 791.11 µg/mL). The final product exhibited a uniform brown-yellow colour, pleasant aroma, and a mildly sweet and pungent flavour, achieving the highest sensory scores. This study provides vital technological parameters to produce high-quality Black ginger bag tea.