Siti Fatimah Mohd Rahim, Norashikin Ahmad Zamanhuri, Dewi Selvia Fardhyanti, Haniif Prasetiawan
The Melastoma Malabathricum L. plant contains multiple bioactive components that can inhibit the growth of bacteria and was traditionally used to cure various diseases. The main objective of this study was to optimize the extraction of Melastoma Malabathricum L. leaf by using microwave technology at varying ethanol concentrations and microwave powers. Additionally, the study aimed to characterize the stability of the extract at various temperatures and their ability to inhibit the growth of bacteria Escherichia coli (E. coli) in water-based emulsion. The extraction was done using different ethanol concentration (50%, 70%, and 95%) with varying microwave power level (300 W, 400 W, and 600 W) has been set to gain the extract. The stability of the extracts in water-based emulsion was determined by observing the pH value, color changes, and viscosity after 14 days of storage at different temperatures (4 °C, 25 °C, and 58 °C). The antibacterial activity of the extracts in water-based emulsion was tested using paper disc diffusion method against Escherichia coli (E. coli) as the bacteria. Based on the result of this study, ethanol with 95% concentration and 400 W microwave power used yields the highest amount of extract by 12.93%. The pH value and the viscosity of the extract in water-based emulsion decreases as temperature increases, and the colour turns darker when stored at high temperature of 58 °C. The biggest diameter of bacterial inhibition zone was measured at 11 mm which was obtained from the sample containing the extract (95%, 300 W). The result concludes that the extraction of Melastoma Malabathricum L. leaf by using microwave technology at various ethanol concentration and microwave power has been optimized, and the stability of the extracts at various temperatures and its ability to inhibit bacterial activity in water-based emulsion has successfully characterized. © 2026, National University of Malaysia. All rights reserved.
School of Chemical Engineering, College of Engineering, Universiti Teknologi MARA, Selangor, Malaysia; Surface Coating Research Group, School of Chemical Engineering, College of Engineering, Universiti Teknologi MARA, Selangor, Malaysia; Chemical Engineering Department, Faculty of Engineering, Universitas Negeri Semarang, Kampus Sekaran Gunungpati, Semarang, Indonesia
