Ultrasound bath-assisted extraction of essential oils from clove using central composite design

• Ultrasound-assisted extraction of essential oils from clove was studied.
• Extraction parameters were optimized using response surface methodology.
• The most significant factor was extraction temperature.
• The major compound in the essential oil was eugenol.
• Essential oil showed high antibacterial activity.

Ultrasound-assisted extraction of essential oils from clove was carried out using central composite design (CCD). The extraction parameters were optimized with response surface methodology (RSM). Three independent variables were extraction temperatures (ranging from 32 to 52 °C), extraction times (ranging from 30 to 60 min), and plant concentrations (ranging from 3 to 7%). The dependent (response) variable was clove extract. In this study, all the experiments were carried out in an ultrasound bath with a frequency of 53 kHZ. A high coefficient of correlation (0.94) was obtained between the predicted and actual clove extract yields. This result demonstrates the validity of the model used in the experiment. The statistical results showed that the extraction temperature had the most significant influence on the clove extract yield. The clove extract contained the following compounds: eugenol, α-caryophyllene, and 2-methoxy-4-(2-propenyl) phenol acetate. The major compound in the clove extract was eugenol. Antibacterial studies showed that essential oils derived from the ultrasound extraction of clove may be used as alternative bactericidal and bacteriostatic agents in the pharmaceutical industry.

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