EXTRUDED CORN GRITS—QUINOA BLENDS: II. PHYSICAL CHARACTERISTICS of EXTRUDED PRODUCTS

Abstract

Quinoa was blended with corn grits at levels of 10%, 20% and 30% and extruded at 15% and 25% moisture respectively, using screws with a 1:1 or 3:1 compression ratio. Extrusion temperatures were 80° and 100°C at the feed section and 100° or 150°C at the compression section, respectively. RPM values were 100, 150 and 200. Quinoa addition produced a darker, less yellow product than corn grits alone. Density, expansion ratio and shear strength were lower for products containing greater levels of quinoa. the most favorable products were produced at a 15% initial moisture content and a 3:1 compression ratio. Products extruded under these conditions had the greater expansion, lower density and lower shear strength than products extruded at 25% moisture or at a 1:1 compression ratio. SEM showed larger, more uniform cells in the 100% corn grits product indicating a more even expansion. A product containing 30% quinoa had a rougher texture, many broken cell walls and less evenly distributed air cells. Copyright © 1991, Wiley Blackwell. All rights reserved