Ultrasonic induced effect on mass transfer characteristics during osmotic dehydration of aonla (Phyllanthus emblica L.) slices: A mathematical modeling approach

Abstract

AbstractThe present work aimed to investigate the effect of ultrasound pretreatment on osmotic dehydration of aonla slices. The aonla slices were subjected to an ultrasonic treatment with a frequency of 40 kHz for 10 min and then subjected to osmotic dehydration in 60°Bx sucrose solution for 300 min. Empirical models such as Azuara, Peleg, Weibull, Page, and Crank model were utilized to predict the kinetics of water loss and solid gain. Artificial Neural Network technique was also used to predict the parameters with immersion time and temperature as input. All models were found to have a good fit. From the analysis, the ultrasound pretreated samples were found to have enhanced rate of mass transfer compared to control samples especially at the early stages of the process. From Azuara Model, the equilibrium water loss and solid gain were ranged between 49.95–53.65 g/100 g and 11.10–22.01 g/100 g. From Crank model, the effective moisture diffusivities in osmotic dehydration were observed to be varied between 9.28 × 10−10–12.47 × 10−10 m2/s and 10.06 × 10−10–19.17 × 10−10 m2/s for atmospheric and ultrasonic conditions. While for solid gain, the values were ranged between 2.36–2.67 × 10−10 m2/s (untreated) and 2.49–2.73 × 10−10 m2/s (treated). The Vitamin C content and color of sample were found to be affected by ultrasound pretreatment (p <.05) and temperature (p <.05). The effective diffusivities attributed to have a significant Arrhenius relationship (R2 ≥.92, p ≤.05). The enhanced moisture loss and solid gain in the product can be explained by the microscopic channels and cell disruption caused by ultrasonic waves.Practical ApplicationThe aonla fruit, native to South Asia, is a very important commodity because of its health and nutritional benefits. Despite its advantages, it is less popular as table fruit because of its low shelf life and astringency. Osmotic dehydration can be used to preserve the fruit, and it causes the partial removal of water from the fruit and improves its taste. Osmotic dehydration being a slow process, can be enhanced by the ultrasound application. The data and findings can be applied to produce stable intermediate moisture content food that can be used as dried fruit or additive with other food products. This study investigates the modeling of ultrasound‐induced osmotic dehydration in order to design the process with low energy and cost.