Phospholipo-proteins which have been enzyme modified may be used as an emulsifier to improve the emulsion stability of frozen products, e.g., during the freeze thaw and vacuum cool processes. Especially preferred is use of the enzyme phospholipase A to modify egg yolk and to use the modified egg yolk as an emulsifier in frozen products. Creation of a more stable emulsion can be expected to improve the overall appearance of the final product both in the frozen state and after the product has been reheated. Although egg yolk is preferred, examples of other phospholipo-protein containing substances include casein, skim milk, buttermilk, whey, cream, soybean, yeast, whole egg, blood serum and wheat proteins. Egg yolk and/or other sources of phopholipo-protein can be subjected to the action of phospholipase A or other enzyme, and then the modified product incorporated into the products of the invention. Alternatively, it is possible to isolate the phospholipo protein from its source and subject the isolated protein to the action of phospholipase A, after which the modified phopholipo-protein is incorporated into the frozen food products of the invention.