The invention relates to manufacture of whey protein extracts, to infant formula and to reducing or preventing food allergy. The whey protein extract is produced from a whey protein-containing composition by contacting a whey protein-containing composition with an aqueous solution to form a sample including a soluble protein-containing component and an insoluble component； recovering the soluble protein-containing component from the sample； and acidifying the soluble protein-containing component, thereby producing the whey protein extract. Extracts produced by the method of the invention may be used in infant formula, as a dietary supplement or foodstuff.
