Kinetics of drying and hydration of the scleroglucan polymer. A comparative study of two conventional drying methods with a new drying process: Dehydration by successive pressure drops

The scleroglucan polysaccharides are mainly used in the petroleum industry but also have applications in the food, cosmetics and pharmaceutical indust ries. For most of these applications, the dissolution rate of hydrocolloids is an important qualitative criterion. In this study, the kinetics of scle roglucan drying was investigated with the aim of improving the hydration ca pacity and the dissolution rate of the polymer. Two conventional methods (h ot air and vacuum drying) were compared with a new drying process: dehydrat ion by successive pressure drops, or DDS (Deshydratation par Detentes Succe ssives). This process involves processing the polymer in a series of cycles that consist in placing it in desiccated air then subjecting it to an inst antaneous (200 msec) decompression to a vacuum (50 mbar). Two parameters we re varied: pressure (P: 4.5-7.5 bars) and processing time at this pressure (t = 5-10 sec). During each decompression, a certain quantity of water is e liminated by vaporisation, improving tile diffusion of water by capillary a ction during hydration. Our results showed that processing time at high-pre ssure (P) has a significant effect oil the drying kinetics. In contrast, pr ocessing pressure was not a critical parameter. The results showed that hot air and vacuum drying of scleroglucan are less effective techniques.