To provide a soy-containing beverage comprising an aqueous liquid containing deflavored soy protein material.

The soy-containing beverage is prepared by (1) preparing an aqueous mixture of the deflavored soy protein material and a sweetener, (2) homogenizing the aqueous mixture, wherein the deflavored soy protein material is prepared in a method comprising (a) a step preparing an aqueous composition of the soy material, (b) a step adjusting the aqueous composition to a pH of about 9-11, to dissolve the soy proteins and dissociating the flavoring compound, (c) a step passing the pH-adjusted aqueous composition through an ultrafiltration membrane, while maintaining the pH in the range of about 9-12, thereby deflavoring the soy material and retaining substantially all of the dissolved soy proteins, and (d) a step recovering the dissolved soy proteins retained by the ultrafiltration membrane, wherein the recovered dissolved soy proteins is the deflavored soy protein material.