Paini Sri Widyawati, Indah Epriliati, Susana Ristiarini, Antoni Ungirwalu, Melvin Emil Simanjuntak
Haplolobus monticola Blumea, a tropical plant endemic to Papua, contains heat-sensitive bioactive compounds such as tannins and phenolics. Effective moisture removal techniques are required to preserve their quality, yet the efficient drying still plays important roles in its utilization for a health food source. This study investigates the drying kinetics and phytochemical stability of its leaves using a non-thermal rotary-wind drying method powered with moisture pressure differences and a forced convection dehydration. Until now, it is still very difficult to find this kind of research. The experiments were performed at various combination factors comprising of airflow velocities i.e., 2.5, 3.0, and 5.5 m/s and parallel-countered basket rotations i.e., 20, 30, and 40 rpm. The counterclockwise rotation was chosen because it would dry faster. Moisture reduction, drying rate, and moisture ratio were analyzed, alongside the best model fitting selected from six drying kinetics models. The Rational model provided the best fit, with R² = 0.9968, RMSE = 0.0147, and χ² = 0.0002 portraying optimally retained phytochemical at 20 rpm and 2.5 m/s for 500 min. The total tannin content reached 1250 mg TAE/kg wet base (wb) of dried matter, DPPH activity exceeded 3450 mg GAE/kg wb of dried matter, and total phenolic content surpassed 16,000 mg GAE/kg wb of dried matter. The findings demonstrate that rotary-wind drying significantly reduces the moisture content of black fruit leaves to below 10%, while effectively preserving heat-sensitive bioactive compounds. Compared to conventional thermal methods, this approach offers a more energy-efficient, making it suitable for small-scale processing of tropical herbal materials with high antioxidant value. © The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature 2025.
Food Technology Study Programme, Agricultural Technology Faculty, Widya Mandala Surabaya Catholic University, Surabaya, 60265, Indonesia; Forest Management, Papua State University, West Papua, Manokwari, 98314, Indonesia; Mechanical Engineering Department, Medan State Polytechnics, Medan, 20155, Indonesia