Whipped egg whites find use as aerating agents in numerous food products.  In some food products, the aerating agent must have a high tolerance to sugar and be heat setable to a light, airy and hard product such as a hard meringue.  In baked goods, the aerating agent must have a good tolerance to flour and be able to set to an elastic state in such products as cakes.  Egg white is able to perform both of these functions. 
Due to the expense of egg whites, many attempts have been made to duplicate the aerating qualities of egg white with less expensive materials.  The use of inexpensive vegetable proteins, such as soy protein, has not been successful.  However, compositions containing hydrolyzed soy protein have been developed which are taught to provide useful whipping agents.  For instance, U.S. Pat.  No.  2,844,468 discloses a whipping composition comprising 70-90% enzyme modified soy protein, 3-15% polyphosphate such as sodium hexametaphosphate, and, optionally, 0-5% sodium aluminum sulfate.  However, this product requires the use of an enzymatically modified or hydrolyzed soy protein.  The enzyme treatment of the soy proteins must be carefully controlled to provide a bland flavored product with no off flavors.  A distinctive flavor even if mild would be a disadvantage in some areas of use of whipping agents, such as meringues. 
A number of prior art processes for forming an egg white substitute from whey proteins have been proposed.  For example, in Netherlands Patent Application No.  72/14,837 (abstracted under Derwent Accession No.  37,726 V), in "Whipping Studies with Partially Delactosed Cheese Whey", by P. Jelen, in the Journal of Dairy Science, Vol.  56, No.  12, pp.  1505-1511, and in U.S. Pat.  No.  3,583,968, heat treatment and pH adjustment procedures are advocated for formation of such products.  The addition of hydrate of lime to a whey solution to form two liquid fractions is advocated in U.S. Pat.  No.  1,387,754.  Adjustment of the pH of the whey solution to about 9-10.5 with subsequent filtration is advocated in U.S. Pat.  No.  3,695,235.  Each of these approaches has certain disadvantages.  The first three enumerated procedures require heating with consequent expenditure of energy and the latter two give a product having inferior utility particularly when the product is used in an egg meringue. 
In copending application Ser.  No.  582,489 there is disclosed a process for preparing an egg white substitute which in general terms, comprises adjusting the pH of a whey protein solution to a value of from about 11 to about 13 followed by a subsequent adjustment of the pH to a value of from about 4.0 to about 6.0 to yield a supernatant solution and a precipitate.  This procedure is carried out in the absence of any heat treatment.  The supernatant can be used as an egg white substitute, particularly in hard meringues.  If the insolubles are rehydrolyzed at an alkaline pH of from about 11 to about 13 they can be used as an egg white substitute, particularly in soft meringues. 
While these prior art materials are advocated for use as egg albumen replacers, most do not pass the sensitive test of hard meringue preparation.  The egg white substitute should be able to foam, hold sugar and heat set.  While these materials can provide some of these functions, improvements in functionality, stability of foams and heat set characteristics are required.