Kinetic Mechanism of Hazelnut Oil Extraction with Ultrasound-Assisted Osmotic Dehydration Pretreatment

Abstract

Nowadays, most of the researches focus on enhancing the oil yield by adjusting the various process parameters or searching for alternative techniques. There is only limited information on investigating the effects of various extraction parameters on kinetic mechanism during oil extraction. The mechanism data can provide additional information to the industry when optimization is needed. Previous work had investigated the effect of ultrasound in extraction process. The main purposes of this study are to apply osmotic dehydration as pretreatment and to investigate the effects of ultrasound amplitude, concentration of osmotic dehydration, and dehydration time on extraction mechanism of hazelnut oil. The kinetic modeling showed that So and Macdonald model was more suitable to describe the mechanism of hazelnut oil extraction with higher R2 values ranged from 0.944 to 0.987 as compared with Perez et al. model. The results showed that applying 30% ultrasound amplitude in dehydration stage could increase the mass transfer coefficient for diffusion step (kd) from 0.019 to 0.044 min−1 due to cavitation effect. Besides, 15% concentration of osmotic solution could limit the diffusion step with lowest kd value of 0.055 min−1 as compared with 5 and 10% concentrations due to blocking of surface by solute in higher concentration of osmotic solution. Lastly, increasing the dehydration time from 45 to 150 min could enhance the oil diffusion process with kd values increased from 0.058 to 0.075 min−1 due to lower moisture content in sample.