A method for preparing compositions comprising heat labile milk proteins is disclosed herein. In certain embodiments, the method involves subjecting a first composition comprising a fat or lipid source and a protein source to a temperature of at least about 130° C. and combining the first composition with a second composition comprising a heat labile milk protein. In another embodiment, the method includes combining a first composition comprising a fat or lipid source and a protein source that has been subjected to a temperature of at least about 130° C. with a composition comprising a heat labile milk protein to form a third composition including a fat or lipid source, a protein source and a heat labile milk protein and packaging the third composition aseptically.