THE EFFECT OF ROBUSTA COFFEE LEAF DRYING METHODS ON TOTAL POLYPHENOLS, CAFFEINE, AND ANTIOXIDANT ACTIVITY OF KAWA DAUN, A TRADITIONAL BEVERAGE OF WEST SUMATRA

Abstract

Kawa daun is a traditional West Sumatran beverage brewed from dried coffee leaves, and its quality depends strongly on drying. This study compared four drying methods for robusta coffee leaves, namely sun drying, traditional smoking for 2 h, oven drying at 50 °C, and oven drying at 70 °C, on moisture content, total polyphenols, caffeine, and antioxidant activity (DPPH IC50), together with sensory acceptance of the brew. A Completely Randomized Design with three replicates was used; data were analyzed by ANOVA and Duncan’s test at 5%. Drying method significantly affected all parameters. Oven drying at 50 °C gave the highest total polyphenols (51.3 mg GAE/g) and strongest antioxidant activity (IC50 55.0 µg/mL) with 5.1% moisture, whereas sun drying gave the lowest polyphenols (38.2 mg GAE/g). Caffeine ranged from 5.1 to 6.1 mg/g. Smoking for 2 h scored highest for aroma (4.5) and taste (4.3). Oven drying at 50 °C is recommended for functional kawa daun and 2 h smoking for traditional products.