polyphosphoric acid 1 d were dissolved into 185 parts of warm water of 60 u00b0 c and as the emulsifiers 10 parts of glycerine monostearate 20 parts of diglycerine monostearate and 3 parts of soybean lecithin were mixed to this after molten under heat this was converted to an emulsion by passing through a highpressure piston homogenizer pressure 150 kg cm 2 u2192 50 kg cm 2 and then spray drying was performed to obtain a sample of powdery foaming agent as the ingredients in aqueous side 53 parts of dextrin 15 parts of maltose 3 parts of sodium caseinate and 1 part of polyphosphate and as the emulsifiers 5 parts of glycerine monostearate 20 parts of diglycerine monostearate and 3 parts of enzymolysis lecithin were used to prepare a sample of powdery foaming agent according to example 1 as the ingredients in aqueous side 39 parts of dextrin 22 parts of maltose 3 parts of sodium caseinate and 3 parts of polyphosphate and as the emulsifiers 10 parts of glycerine monostearate 20 parts of diglycerine monostearate and 3 parts of soybean lecithin were used to prepare a sample of powdery foaming agent according to example 1 as the ingredients in aqueous side 38 parts of dextrin 20 parts of milk sugar and 3 parts of sodium caseinate and 1 part of polyphosphate and as the emulsifiers 10 parts of glycerine monostearate 25 parts of diglycerine.