Acoustic Cavitation-Enhanced Hydro-Distillation of Rosemary (Salvia rosmarinus) Essential Oil: Response Surface Optimization of Ultrasonic Pretreatment Parameters for Maximized Yield

¹ Amity Institute of Horticulture Studies and Research, Amity University, Noida, India
² Amity Food and Agriculture Foundation, Amity University, Noida, India

^* Corresponding author: This email address is being protected from spambots. You need JavaScript enabled to view it.

Abstract

Rosemary (Salvia rosmarinus) essential oil (EO), rich in bioactive components, is known for its broad-spectrum antioxidant and antimicrobial activity. Although reliable, conventional hydro-distillation has the problem of long extraction periods, low yields, and thermal degradation of thermolabile volatiles. The results indicated that the ultrasonic pretreatment was systematically evaluated in this study as an enhancement method before the extraction process using a Response Surface Methodology (RSM) for three factors: temperature (20–40 °C), ultrasonic time (10–30 min), and hydro-distillation (HDE). EO yield ranged from 0.62% (untreated control) to 1.64% (R8: 20 °C, 20 min), representing a 2.65-fold improvement. Process variables alone and the combination of those variables were found to have statistically significant effects on recovery. The optimum conditioning model parameters, the pretreatment temperature and conditioning time were determined based on the results of numerical optimization as 20 °C and 22 min, respectively, with the recovery yield of EO in the model of 1.618%, and the model value under optimum condition obtained from experiments was 1.71%, recovering the results of EO recovery and demonstrating the model's adequacy (R² = 0.9562). The results demonstrated that ultrasonic treatment at low intensities and durations significantly improved the efficiency of rosemary EO extraction, providing a new strategy to be scaled up in the industrial production of EOs that is energy efficient.