Functional and physical properties of naked barley-based unexpanded extrudates: effects of low temperature

Abstract

The purpose of this study was to provide a new approach to producing a slowly-digestible snack with sensory appeal suitable for people with hyperglycemia. The study was based on naked barley supplemented with other functional components and used low-temperature extrusion technology. The effects of the extrusion temperature (Et = 65–85°C), feed moisture (Fm = 25–35%), and screw speed (Ss = 60–80 rpm) were studied systemically, aiming at minimizing the glycemic index and maximizing the radical scavenging rate while obtaining a good texture and pleasant sensory characteristics. The best response was obtained with an Et of 74.24°C, Fm of 35%, and Ss of 80 rpm. Under these conditions, barley extruded with multiple grains showed a lower degree of gelatinization (70.17%), lower glycemic index (29.37), higher radical scavenging rate (53.66%), and higher sensory evaluation (86) compared to those of extrudates with only naked barley. The present study suggests that the low-temperature extrusion method can effectively produce snacks with a high radical-scavenging rate, slow digestion characteristics, and high market acceptance.