Image Number 5 for United States Patent #6383545.
An improved low shear extrusion and dehydrating apparatus (10) and method is provided for the continuous extrusion of various starting materials (e.g., starch-bearing grains or starch fractions thereof, proteinaceous materials and/or nutraceuticals) to yield improved products, especially cold water swelling or soluble starch products. The invention is also useful for forming pre-gelled starch products and for processing starch-bearing materials using little or no surfactant. The apparatus (10) preferably includes an elongated extruder (18) together with a tubular die assembly (20) coupled to the outlet of the extruder barrel (32), wherein the volumetric ratio of the die assembly (20) to the free volume of the extruder (18) is at least about 2, and the ratio of die assembly retention time to the extruder retention time is at least about 5. In another embodiment, the apparatus (10) further includes a dehydration assembly (14) having an agitator (56) operatively coupled to a drying or dehydrating tower (66) for drying and comminuting the extrudate after it emerges from die assembly (20).