Abstract: Qingke (highland barley) and oats are rich sources of β-glucan; however, a systematic comparison of the structural and physicochemical properties of β-glucans across different species and varieties remains limited. This study investigated the structural characteristics, physicochemical properties, and bioactivities of β-glucans from blue qingke, commercially available qingke, and oats using infrared spectroscopy and rheological analysis. Infrared spectral characterization revealed that all three β-glucans exhibited similar plant polysaccharide structures with a βconfiguration, yet significant differences in molecular structure were observed. Based on molecular structural differences, the physicochemical functional properties of β-glucans from different sources were further analyzed. Results showed that blue qingke β-glucan contained fewer hydroxyl groups and proteins but a greater variety of functional groups. Compared to the other two β-glucans, it exhibited higher oil-holding capacity, foaming ability, and foam stability, lower emulsifying ability but higher emulsion stability, and significantly lower water-holding capacity and solubility. Rheological analysis indicated that all three β-glucan solutions demonstrated non-Newtonian pseudoplastic shear-thinning behavior, with predominant solid-like properties. Additionally, blue qingke β-glucan exhibited superior ABTS⁺ and DPPH radical scavenging activities compared to the other two β-glucans. This study provides fundamental insights into the practical applications of qingke and oat β-glucans and offers new perspectives for the development of functional foods.
Keywords: Qingke; oat; β-glucan; structural characterization; functional characteristics