Instant Controlled Pressure Drop (DIC) Texturing of Heat-Sensitive Spray-Dried Powders: Phenomenological Modeling and Optimization

Abstract

Powders of expanded granules generally get high functional characteristics due to porous structure of such granules. The present study aimed at comparing the two ways of high-pressure air or steam alternatively used in détente instantanée contrôlée (DIC; French for instant controlled pressure drop) to achieve the modified three-stage spray-drying operation. Both operations were studied in terms of the process performance and functional/structural powder quality in the case of skim milk. The initial water content, the temperature levels, and the initial and final pressures contribute together to define the amount of expanding air or vapor thus generated. This is an important texturing parameter strictly combined with rheological and glass transition to define the texturing phenomenon. Response surface methodology—design of experiments (RSM-DoE) was achieved with DIC pressure, treatment time, and water content as independent variables for both operation ways. The analyses of the technological, physical, and structural properties of untreated and DIC textured powders were carried out and considered as response dependent variables. The results illustrated that whatever the type of DIC, the optimized DIC treatment implied a controlled increase in porosity, interstitial air volume, and compressibility, as well as specific surface area and reconstitution aptitude.

Keywords:

• Expanded granule powder
• Instant controlled pressure drop (DIC)
• Particle size distribution
• Specific surface area (SSA)
• Spray-drying
• Texture

ACKNOWLEDGMENTS

The authors draw thanks to ABCAR DIC Process Company and Mr. Pierre SCHUCK from INRA-Rennes for providing DIC equipment and technical support, and spray-dried materials, respectively. The authors acknowledge Dr. Egle Conforto from LaSIE (University of La Rochelle) for achieving scanning electronic microscopy (SEM).