Impact of a Full Range of Amylose Level on Pasting and Gelling Properties of Barley Starches at High-Temperature Heating

Abstract

Pasting and gelling behaviors of barley starches isolated from Cinnamon (waxy of 3.3% apparent amylose; WB), Golden Promise (normal of 26.2% amylose; NB), and amylose-only (high-amylose of 97.8% amylose; AO) varieties were examined over 95-140 °C cooking. AO starch exhibited significantly higher gelatinization temperatures than those of WB and NB, thereby the former displaying negligible pasting viscosity at 95 °C heating. At 140 °C, AO starch was completely gelatinized and able to develop viscosity, particularly at the final pasting stage. Gel hardness of NB gradually decreased with higher cooking temperatures. After 140 °C cooking, only AO starch formed a gel, exhibiting the largest hardness among the studied gels/pastes. Gelation mechanisms of the barley starches at 95-140 °C cooking were elucidated by visualizing their gel/paste microstructures under scanning electron microscopy. The insightful information on the physicochemical properties of the barley starches possessing 3.3-97.8% amylose will be meaningful for their industrial applications.

Keywords: Barley starch, Amylose content, Thermal properties, Pasting properties, Gelling properties, Gel microstructure