Investigation the effect of ultrasonic pretreatment on drying rate of cherry and process modeling using genetic algorithm-artificial neural network method

Due to their high moisture content, cherries have a very high rate of spoilage and require the use of some post-harvest treatments in order to be effectively preserved. Drying is one of these preservation methods. Drying time can be shortened by using ultrasonic waves as a pretreatment before drying agricultural products. The genetic algorithm–artificial neural network method has a high ability to find the optimal value of a complex objective function. In this study, the effect of sonication treatment for 0, 3, 6, and 9 minutes on drying time, weight changes, and rehydration of cherries was investigated. In the next step, this process was modeled by genetic algorithm–artificial neural network method with 2 inputs (drying time and ultrasonic pretreatment time) and 1 output (weight loss percentage). The results of this research showed that sonication for up to 3 min increased the rate of moisture removal from cherries and thus reduced drying time. 3-min treatment with ultrasound increased the rehydration of dried cherries; but as the treatment time increased to 6 min and 9 min, the amount of rehydration decreased. Genetic algorithm–artificial neural network modeling results showed that a network with a 1-4-2 structure in one hidden layer and using the hyperbolic tangent activation function can predict the weight loss percentage of cherries during drying with a high correlation coefficient and a low error value. According to the results of sensitivity analysis test, drying time was the most effective factor in changing the weight loss percentage of cherries during the drying process. In general, the best conditions for drying cherries are pretreatment with ultrasound for 3 minutes followed by drying the product with hot-air. Based on the modeling results, the genetic algorithm–artificial neural network method can also be used to predict the parameters of the cherry drying process.