Comparative Studies

Abstract

This chapter is the longest and probably the most important for the decision-making between the available drying techniques. Several vacuum drying techniques are compared to each other and to conventional drying techniques in terms of product quality and engineering aspects. Vacuum drying usually provided better results than conventional processes, such as hot air drying, in terms of product quality. Nevertheless, hot air drying is still cheaper than vacuum drying and depending on the product value it could be more interesting to use a cheaper drying technique. The differences between conventional vacuum drying, freeze-drying and microwave-vacuum drying are elucidated and quantified. New processes of subatmospheric drying that have been developed during the last years are also presented. A search in electronic databases shows that vacuum and conventional drying processes for foods have been compared since the 1940s and this fashion of research remains popular until nowadays. Definitely, this chapter is very useful for entrepreneurs and researchers interested in choosing the most suitable drying technique for a selected food product.