Optimization of Bioactive Compound Extraction from Fresh Subgrade Turmeric (Curcuma longa L.) Using Ultrasound Assisted Extraction (UAE) Dodyk pranowo1*, Hendrix Yulis Setyawan1, Endrika Widyastuti2, Pandu Waskito1, Ulaya Warda Aziza1
1 Department of Agroindustrial Technology, Faculty of Agricultural Technology, University of Brawijaya, Jl Veteran Malang, Indonesia
2 Department of Food Science and Biotechnology, Faculty of Agricultural Technology, University of Brawijaya, Jl Veteran Malang, Indonesia
*Email: dodykpranowo[at]ub.ac.id
Abstract
Turmeric (Curcuma longa L.) rhizomes are a valuable source of curcuminoids and essential oils, particularly turmerone-rich fractions that are widely utilized in the food and health industries. However, conventional extraction methods often result in suboptimal oil yield. This study optimized the ultrasound-assisted hydrodistillation (UAHD) of fresh, subgrade turmeric using Response Surface Methodology (RSM) with a central composite design (13 runs). Two ultrasound pretreatment factors: amplitude (15-65 (persen)) and time (15-45 min) were applied prior to 2 hour hydrodistillation with water (1:8, w/v). The responses measured were oil yield, refractive index (RI), and density. Quadratic models adequately described oil yield (R (kuadrat) = 0.9129) and density (R (kuadrat) = 0.9233), while a two-factor interaction model best fit RI (R (kuadrat) = 0.9403). Ultrasound time had a stronger effect on yield, whereas amplitude dominated RI. Multi-response optimization identified 45 (persen) amplitude and 32 min as optimal conditions (desirability = 0.869), predicting yield of 0.969 (persen), RI of 1.503, and density of 0.960 g mL(pangkat -1). Verification confirmed predictions within (plus min) 5 (persen), with the optimized oil showing an optical rotation of (plus min) 50.945. These findings demonstrate that UAHD is a rapid, water-based, and scalable pretreatment technique that significantly enhances turmeric oil recovery and quality compared to conventional hydrodistillation.
