Home Pasteurization of Milk

Abstract

THE advantages of pasteurized milk need not be dwelt upon in this JouRNAL. Our purpose is to report experiments upon the use of vacuum and insulated heat retaining bottles to pasteurize milk in small quantities suitable for home use. This is a part of a program of the Illinois State Department of Public Health to reduce infant mortality in communities too small to enjoy the benefits of commercially pasteurized milk. Illinois has an approximate population of 4 million people living outside of the city of Chicago, at least 70 per cent of which uses raw milk. A recording thermometer was used for these experiments. The readings were checked with certified mercury thermometers. Water, milk and other fluids were heated to various temperatures and placed in vacuum vessels of various sizes and types, and the heat retaining efficiency of each vessel graphically recorded on a circular ruled paper by a moving writing point, moved by a time clock. The results are presented in tables, calculated from averages from the time and temperature graphs. The temperatures varied from 1000 to 2000 F. We are only concerned in this article with those temperatures that are of practical use in the pasteurization of milk for human consumption. Milk was heated in an open vessel to a given temperature, then placed in a vacuum bottle and the heat retaining efficiency of the closed vacuum vessel determined. Such a vessel can act as an incubator under certain conditions. The object of our experiments was to find a vessel of the proper size that would retain the heat of the milk for the longest period before it served as an incubator for its contents. This part of the problem divided itself into 3 factors: (1) duration of the holding or pasteurization temperature; (2) length of time that the milk would be warm but wholesome; (3) time when the vessel cooled to a degree that would incubate its contents. When the continuous recording thermometer is used over a long