PASTEURIZATION OF GRADE “A” MILK AND MILK PRODUCTS BY STEAM INJECTION

Abstract

Steam injection systems are in common use in some parts of the United States. They have not been recognized, however, as a satisfactory method for pasteurizing milk and milk products because of possible poor mixing of steam and product, vapor formation in the holding tube, and inadequate public health controls. Recent research has solved these problems and steam injectors may be used to pasteurize milk products when the steam and product flows are isolated from the pressure fluctuations in the injection chamber, when no vapor is formed in the holding tube, and when non-condensable gases are eliminated from the steam supply. The injection chamber is isolated by installing supplementary orifices of a proper size at the injector ports to maintain a product pressure drop of 10 psi across the injector. Vapor formation is prevented by maintaining a holding tube pressure 10 psi above the boiling pressure of the liquid product. Non-condensable gases are eliminated from the steam supply by installing an approved deaerator in the boiler system.