Effect of ultrasound‐assisted hydrodistillation on extraction kinetics, chemical composition, and antimicrobial activity of Citrus jambhiri peel essential oil

Citrus jambhiri processing generates 40% peel waste with considerable waste management constraints. Interestingly, these peels are a rich source of essential oil. Hence, in this study, the essential oil was extracted from fresh peels and peel powder (PP) of C. jambhiri using hydrodistillation (HD) and ultrasound-assisted hydrodistillation (USHD). Kinetic study, physicochemical, antimicrobial, and chemical composition of the essential oil obtained from PP and fresh peel with albedo (FPA) and without albedo (FPWA) using HD and USHD was studied. The kinetic study was further experimentally validated using the first and second-order kinetic model. The integrated equations were used to test the fitting of the model with obtained experimental data. Kinetics of oil extraction from PP using USHD showed that extraction process best fitted in second-order kinetic model with a high coefficient of determination (R2 = .999), yield (3.63%) and extraction rate constant (K2 = 0.0306), showing that it validated the process thoroughly. The physicochemical properties of essential oils obtained from both extraction methods fall within an acceptable range. Specific gravity, acid value, and total phenolic content showed no significant difference between both extraction methods while others differed significantly. The antioxidant and antimicrobial activity increased with ultrasound treatment. GC–MS analysis of different oil samples revealed that 10 compounds extracted from each extraction with the highest amount of d-limonene (61.29%) were obtained from PP using USHD. USHD stands as a fast, efficient, and economical method for extracting essential oil and can be a potential source for nutraceutical and pharmaceutical industries. Practical Application Citrus jambhiri peels are discarded as waste material. Its comprehensive utilization is urgently needed. Essential oil from citrus peels is an important biologically active substance containing tens to hundreds of bioactive compounds with health-promoting characteristics. Ultrasound-assisted hydrodistillation is a promising extraction technique to enhance product quality and reduce production time and consumed energy. Application of the novel proposed methods combined with conventional or alternative to increase the extraction rate on an industrial scale could be recommended.