A Study of Dehydration of Fish Using Successive Pressure Drops (DDS) and Controlled Instantaneous Pressure Drop (DIC)

Abstract

Many studies have recently been carried out with a view to improve the processes used in drying foodstuffs. Optimization of the classical methods has been improved in terms of cost (mainly energy) and quality of the end product. Other work was devoted to developing new processes and a special effort was made to integrate texturing by controlled instantaneous pressure drop (DIC) into the standard drying by hot air. More recently, a new process of dehydration by successive pressure drops (DDS) has been defined. The aim of this study was to test these processes using two types of fish: the Atlantic salmon (Salmo salar) and the white tuna (Thunnus albacore), chosen mainly for the fact that they represent fatty and semi-fatty fish, respectively. A comparative analysis of the DDS and DIC processes with standard methods such as hot air convection, vacuum conduction and freeze-drying was carried out. The processes were first optimized and the comparison was made on the basis of the operation kinetics and of a physical, structural, and functional characterization of the product. Thus the analysis included measurements of the sample density, rehydration capacity, water activity, and color. Both DDS and DIC, in a similar but distinct manner, proved to be much more satisfactory than standard drying methods for improving the functional and quality aspects of the end product while limiting as much as possible the cost.