Abstract: The method of manufacturing either aqueous soltuion of lactoferin, iron preparation and sodium bicarbonate. or aqueous solution of iron lactoferrin; and adjusting its electric conducitivity (.OMEGA.mS/cm) and its hydrogen ion concentration (pH) so that it meets the conditions provided by the formulae that follow; pasteurizing by heat; and manufacturing iron-fortified beverage using above materials; and having high bioavailability of iron and maintaining physiological functions of lactofe-rrin.

Abstract: A method of preparing iron-fortified beverage, wherein either aqueous solution of lactoferrin, iron and sodium bicarbonate or aqueous solution of iron lactoferrin is adjusted to the ionic strength to satisfy the conditions given by the formulae below and sterilized by heat; solution of the ingredients other than the above is also sterilized by heat; and the two are mixed to obtain the product: and a method of processing iron-fortified beverage, wherein all ingredients including lactoferrin are dissolved in water and, if the ionic strength of the solution is adjustable to the conditions given by the following formulae, adjusted to the ionic strength given, and sterilized by heat to obtain the product.log I.ltoreq.-T/66.7-0.1(wherein 60.ltoreq.T.ltoreq.80)log 1.ltoreq.-1.3(T.gtoreq.80)(T indicates temperature of sterilization in degrees Celsius.