Advanced food products and process engineering (SAFES) ii: Application to apple combined drying

Abstract

Different dehydration techniques are widely used to stabilize fruits. Numerous papers about dehydration methods such as air drying (AD) or osmotic dehydration (OD) are being published around the world. Vacuum impregnation (VI) pre-treatment may be used as a tool both to improve mass transfer and to develop engineered products (Fito et al., 2001). In this paper, a solid food is considered as a monophasic and homogenous system, and product humidity is considered as the main variable related to quality characteristics of the final product being correlated with process conditions (mainly air temperature and velocity). Nowadays, consumers are much more demanding, calling for products with good texture, color and nutritional value. Quality is becoming a more complex concept that affects the functionality of the product (Fito and Chiralt, 2003). In this situation, foods have to be defined by considering some of the structural, sensorial, physical-chemical and nutritive aspects. The changes in every considered characteristic, along with drying processes, need to be taken into account, and mechanistic correlations among these characteristics and process variables must be established (Torreggiani and Bertolo, 2001). A new methodology that allows us to consider structural, physical- chemical and nutritive aspects when defining a fruit, while also analyzing phase transitions, structural changes and transport phenomena in a systematic way (SAFES) (Fito et al., 2006) has been applied to dehydration of apple by combined methods.