Puffed extruded corn-grits and soybean mixtures for snack use

Abstract

The objective of this work was to study the effect of barrel temperature (BT) on expansion ratio (ER) and on water solubility index (WSI) of puffed extruded corn-grits and soybean mixtures (80:20 and 70:30) and to verify their sensory characteristics, while flavored for snack use. Brabender twin-screw extruder with a constant feed rate of 20.8 kg/h, a constant screw speed of 100 rpm at an extruder exit through 5 mm die was used. The extruder barrel temperatures were zone 1 (60ºC) and zone 2 (90ºC) and they were variable in zone 3 (90, 110, 130 and 150ºC) and zone 4 (110, 130 and 150ºC). An increase up to 110ºC in BT at zone 3 caused an increase in ER and WSI of puffed extruded products and above 110ºC caused a reduction in these indexes. An increase in BT at zone 4 resulted in an increase in ER and WSI, except for puffed extruded products submitted to 130 and 150ºC in zone 3. Puffed extruded product with 80% corn-grits and 20% soybean, submitted to BT at 60, 90, 110 and 150ºC and flavored with onion, presented better appearance, texture and flavor, being the preferred by consumers. No trypsin inhibitor activity was detected in the products.