Effect of Ethanol Pre-treatment on Strawberry Convective Drying with Heat Pump

Abstract

Drying, as an important process in product conservation, has a direct influence on post-harvest processes. The heat pump dryer is an air heating and dehumidification system which uses refrigeration cycles to allow the drying process, in order to increase the shelf life of the products, facilitating storage and transport processes. However, high temperatures of convective drying processes can cause irreversible damage to the physical, chemical and biological quality of agricultural products, since they are thermosensitive. Using pre-treatment with accelerating agents, such as ethanol, has shown good results in improving drying quality, as they increase the drying rate and preserve the physicochemical properties of the products. Thus, processes that can be combined with the performance of dryers and the quality of agricultural products are necessary, as well as allowing their optimization in relation to operational parameters. Drying kinetics in a heat pump dryer in a partially closed configuration will be estimated using the Fick's second law model, while the drying air conditioning performance will be evaluated by the specific moisture extraction ratio (SMER) and the coefficient of performance (COP). The product quality will be evaluated according to the chemical and physical-chemical properties of the samples before and after the drying process, analyzing color, texture, viscoelastic properties, rehydration rate, water activity and carotenoids, anthocyanins and ascorbic acid contents, in order to evaluate the influence of pre-treatment of immersion in ethanol.