An acidic, foam having a pH of less than about 4, and preferably from about 2.5 to about 3.5, is provided. The foam is produced from a formulation which is a mixture of an emulsion component and an acidic component. The emulsion component contains water, a hard fat, a sweetener, whey protein, non-ionic stabilizer, and a non-ionic emulsifier. The acidic component contains an edible acid in an aqueous solution. The acidic component may optionally contain a milk protein source and a non-ionic emulsifier. The foam is useful as a whipped topping which has freeze thaw stability and can be kept at refrigeration temperature for at least three weeks.