Heat treatment of milk in domestic microwave ovens

This review deals with the ''state of the art'' regarding microwave heating of milk using household equipment with a frequency of 2450 MHz. The effect of microwave heal treatment depends on the quantity of the product and the geometry of the vessel used. Microwaves do not penetrate deeply into food which can lead to overheating at the surface or to insufficient warming of the total product. In some cases, infant formulae heated to too high temperature by microwaves were found to be hazardous for infants due to scalding and burning. The literature on the effects of microwave heat treatment on microorganisms and nutrients in milk, such as proteins, enzymes and vitamins, is inconsistent. Reported values are combined in tabular forms. Different parameters are included such as the conditions of heat treatment, type and volume of product, the power of the oven, the temperature and time of exposure. The formation of D-amino acids in microwave heat-treated milk, which was indicated some years ago, results from extreme heat. Household equipment does not use these conditions. Therefore, fears about the formation of D-amino acids in microwaved milk can be ignored. Biological experiments showed no evidence for the hazards of microwave heat treatment of milk.