Optimization of Extraction Process of Essential Oil from Bergamot Peel and Analysis of Its Components and Antioxidant Activity

In this study, cellulase-assisted steam distillation was used to extract essential oil from bergamot peel. Based on the single factor analysis of enzymatic hydrolysis pH, enzymatic addition amount, enzymatic hydrolysis temperature and enzymatic hydrolysis time, the extraction process was optimized by using Box-Behnken response surface design method. Moreover, the chemical compositions of the extracted essential oil were analyzed by Gas chromatography-mass Spectrometry (GC-MS). Finally, the antioxidant activities of the essential oil was evaluated by the scavenging rates of ABTS⁺· and DPPH·. According to the research results, 3.11% yield of essential oil was achieved under the optimal extraction conditions: enzymatic hydrolysis of pH5.2, enzymatic dosage of 0.7%, enzymatic hydrolysis temperature of 52 ℃, and enzymatic hydrolysis time of 2.1 h. A total of 42 compounds were identified from the extracted peel essential oils. Among them, linalool acetate had the highest (14.72%) relative content, followed by d-limonene (14.58%) and linalool (8.89%). Besides, according to the results of antioxidant activity study, the essential oil extracted by this method presented good antioxidant activity in the experimental concentration range, and showed an obvious dose-effect relationship. The scavenging rate of ABTS⁺· reached 91.20% when the concentration of essential oil was 40 mg/mL; and the scavenging rate of DPPH· reached 93.19% when the concentration of essential oil was 70 mg/mL. Therefore, this optimized process has high yield of essential oil and can be developed as a natural antioxidant.