Drying of peaches by a combination of convective and microwave methods

Abstract

AbstractThe aim of this work is to study a method to extend the storage life of peaches reducing energy and time consumption and ensuring food quality. The conventional method of hot air dying presents many drawbacks, whereas the microwave drying usually leads to overheating and textural damage. Thus, in this work, a combination of convective and microwave methods, more specifically a two‐stage drying process with an initial convective air drying followed by a microwave drying (microwave finishing), was studied for the drying of peaches. Peaches dried at 70°C for various times, 200, 278, 355, 433, and 510 min, were then dried in a microwave oven at powers of 300, 500, and 800 W. Drying rates were examined, whereas dry peaches were characterized for their color, antioxidant capacity, shrinkage, and rehydration ability under optimized conditions for the situations with and without pretreatment with ascorbic acid. Mass transfer of water was described by nine empirical models and by the diffusional approach. The shrinkage of peach tissue during microwave finishing was evaluated and diffusion coefficients were assessed with shrinkage considered. The microwave finishing reduced the drying time by 89 ± 40%, while a smaller shrinkage was observed, with better rehydration characteristics.Practical applicationsPeaches are important commodities in terms of global agricultural production. As peach is a perishable product with a short shelf‐life, the food industry has been forced to find methods, such as drying, that extend its storage life by months. The conventional method of hot air dying presents many disadvantages. Last decades, microwave drying proposed an alternative way to improve the quality of dehydrated products. However, microwave is rarely used alone as a drying method and is usually combined with other drying techniques. The main goal of this work is to study an innovative method to extend the storage life of peaches reducing energy and time consumption and ensuring food quality.