Highly porous food-grade powders with enhanced functionalities can be produced with the aid of extrusion technology, stated Gilles Maller with Clextral at Session 079 “Next Generation of Extrusion Processing: New Opportunities and Industrial Benefits” on Tuesday morning. Called extrusion porosification technology (EPT), the technique can transform highly viscous and heat-sensitive raw materials into powders with improved rehydration properties.
The system works by adding gas in an aeration zone in a twin-screw extruder, which feeds a high-solid stream of porous product into a spray dryer. Product applications include milk, flavors, coffee, oatmeal, milk protein concentrate, eggs, ice cream mix, probiotics, and highly viscous products that cannot be spray dried.
Research comparing EPT to conventional spraying drying of milk protein concentrate (85%) showed that the EPT-treated product was more spherical than the conventional spray dried product, resulting in faster dissolution and better solubility. Another study comparing EPT to conventional spraying drying of coffee concentrate revealed the that EPT-treated product had greater flavor retention.
In general, EPT offers improved cold water rehydration, better flavor retention, and energy savings. The spray dryer in the EPT system can operate at lower temperatures (i.e., 20–50°C) than conventional spray drying. There is no need to instantize products, and the EPT system can be cleaned-in-place (CIP).