Physical properties and texture of gluten-free snacks supplemented with selected fruit additions

Extrusion-cooking is used to produce directly expanded gluten-free snacks, especially for consumers with celiac disease. The aim of the study was to evaluate the effect of various fruits type supplementation as well as the processing screw speed on the physical properties and texture of ready-toeat corn-based gluten-free snacks. Black elderberry, chokeberry and strawberry were dried and used in the amount of 5 to 20% as a corn grit replacement. The directly expanded snacks were processed with a single-screw extruder at various screw speeds (80 and 120 rpm) and tested to measure their expansion ratio, bulk density, colour profile as well as their texture profile. The results showed the various effects of adding different types and amounts of fruit on the physical properties and texture of supplemented gluten-free snacks. A higher amount of fruit resulted in a significant decrease in the expansion ratio and an increase in the bulk density of the snacks. Reduced lightness and a more pronounced red tint were observed when red fruits were added. The desired hardness of the snacks suggested that the addition of fruit should be retained below 15% of the recipe content. The screw speeds applied showed a significant effect on the expansion, bulk density and texture of the tested snacks