Provided is a method of treatment of an alcoholic beverage, particularly beer or wine, for removing ingredient(s) causing undesirable sulfury and/or fatty flavor(s), by contacting the beverage with a composition having a polymer-hydrogen peroxide complex, wherein the polymer is derived from at least one N-vinyl lactam monomer, and wherein the hydrogen peroxide is present in an amount from about 1% by weight to about 50% by weight of the complex. Provided further is a method of treatment of an alcoholic beverage to remove at least (a) at least one ingredient causing at least one undesirable sulfury and/or fatty flavor, and (b) at least one ingredient causing colloidal haze, including contacting the beverage with a composition described herein. Provided furthermore is an alcoholic beverage obtained by the method(s) of treatment described herein.