This is a method to determine β-glucan content in barley and oats. Lichenase is used to hydrolyze the (1→3)-4 link in (1→3)(1→4)-β-D-glucan. The resulting mixed-linkage β-oligosaccharides are separated from the insoluble material by centrifugation. An aliquot is removed to determine free glucose (sample blank), and duplicate aliquots are further hydrolyzed to glucose using β-glucosidase. Subsequent colorimetric measurement of the derived glucose is performed using glucose oxidase/peroxidase reagent. This method is suitable for flours from whole oat, barley, and rye grains, milling fractions, and unsweetened cereal products. With minor modifications (described in Reference 1), the method may be used for cereal products containing high levels of simple sugars (glucose, sucrose, fructose, and corn sweeteners).