Estimation of mass transfer coefficients of the extraction process of essential oil from orange peel using microwave assisted extraction

• Microwave assisted extraction mass transfer coefficients of citrus EO were obtained.
• Mechanisms of extraction were influenced by the sample characteristics.
• Particle size significantly affected the solid phase mass transfer coefficient.
• Particle size and moisture content influenced citrus essential oil yield.
• Two controlling phases were identified during mass transfer modeling of extraction.

Microwave assisted extraction (MAE) is an emerging technique of extraction that improve yields and reduce process time and energy. The aim of this work was to evaluate the effect of different MAE process parameters in the extraction yield of orange peel essential oil (EO), and the description and simulation of this process with mathematical models based on mass transfer fundamentals. For the assessment of process parameters effects on EO yield, different extractions were carried out following a two-level factorial design varying orange peel particle shape (spheres or plaques) and moisture content (dry or not), as well as microwave potency (360 or 540 W). Results demonstrated that particle size, moisture content, and its interaction significantly affected (p < 0.05) the yield obtained and had an influence on the extraction mechanism. Model parameter values associated to mass transfer coefficients (k1 and k2) indicated that diffusion was the process that defined extraction velocity.