Optimization of Rosemary (Rosmarinus officinalis L.) Essential Oil Extraction using Solvent-Free Microwave Extraction (SFME) Method and Box–Behnken Design

Chemical Engineering Department, Sepuluh Nopember Institute of Technology (ITS), Surabaya 60111, Indonesia

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Abstract

Rosemary essential oil is widely utilized in pharmaceutical, cosmetic, and food industries due to its bioactive components. Solvent-Free Microwave Extraction (SFME) offers a green and energy-efficient alternative to conventional hydrodistillation. Previous studies on rosemary essential oil extraction using SFME or RSM have generally focused on isolated process parameters or limited optimization scopes. The novelty of this work lies in the systematic and simultaneous optimization of microwave power, feed-to-distiller ratio, and extraction time using a Box–Behnken Design, enabling a comprehensive evaluation of their individual and quadratic effects on essential oil yield. This study aims to optimize rosemary essential oil extraction using Response Surface Methodology (RSM) with a Box–Behnken Design (BBD). Three variables were evaluated : feed-to-distiller ratio (0.05–0.15 g/mL), extraction time (30–90 min), and microwave power (150–450 W). A quadratic model was successfully developed and validated through analysis of variance (ANOVA). The optimum conditions were achieved at a feed-to-distiller ratio of 0.10 g/mL, an extraction time of 60 min, and a microwave power of 300 W, resulting in a maximum essential oil yield of 3.1679%. The RSM–BBD model demonstrated strong predictive capability, confirming the significant influence of quadratic terms. The optimized SFME method provides an efficient, solvent-free extraction approach with potential applicability for industrial-scale natural product processing.