Analysis of β-glucan molar mass from barley malt and brewer's spent grain with asymmetric flow field-flow fractionation (AF4) and their association to proteins.

•Barley variety and steeping change more β-glucan molar mass than malt mashing.•Adding proteolytic enzymes lowers the molar mass of large β-glucan species.•Proteins might be linked to β-glucan and affect the molar mass.