Physicochemical properties of buckwheat albumin

For prevention of diabetes mellitus, it is effective to suppress or retard the increase in postprandial blood glucose level. We have already shown that buckwheat albumin inhibits α-amylase and suppresses postprandial hyperglycaemia even after the hydrolysis by digestive enzymes. However, there is no detailed report on the functional properties of buckwheat albumin for its industrial use. In this study, we evaluated emulsifying and foaming properties of buckwheat albumin before and after proteolytic hydrolysis in addition to the thermal stability.Thermal stability of buckwheat albumin was measured as the residual α-amylase inhibitory activity after heating at 100°C for 10–120 min. For the evaluation of emulsifying and foaming properties, buckwheat albumin and its hydrolysates were dissolved in citrate-phosphate buffer at pH 3–6. Emulsifying property was evaluated as the turbidity of emulsion 0–30 min after homogenization of the sample solution with corn oil. Foaming property was measured as foam volume of the sample solution 0–30 min after whipping with a household type mixer. Foaming and emulsifying properties of egg albumin were also measured for comparison. As a result, buckwheat albumin showed high thermal resistance even after boiling for 120 min. Buckwheat albumin showed higher emulsifying and foaming properties than egg albumin in the pH range of 3-6. Although proteolytic hydrolysis reduced emulsifying property of buckwheat albumin, it retained high foaming property. These findings suggest that buckwheat albumin can be applied not only for a functional food material to prevent diabetes but also for a texture improver for bakery products such as bread and cakes.