572 IOWA DEPARTMENT OF AGRICULTURE. 



to be in perfect condition, but favored pasteurized milk under ordinary 

 conditions. 



Dr. Fleischmann, together with Dr. August Morgen, and other European 

 scientists conducted experiments which lead to the conclusion that the 

 nitrogenous matter in milk which has been submitted to a high tempera- 

 ture is somewhat more digestible than in fresh milk. 



Pasteurization of milk is done very satisfactorily by intermittent 

 pasteurization, whereas for cream it is necessary to use a continuous 

 pasteurizer. It is a mistake when people conceive the idea that they will 

 start to make pasteurized butter, and first experiment awhile before they 

 go to the expense of buying a pasteurizer. The result is they start to 

 pasteurize their cream in cans. If cream, especially that cream which 

 is rich in butter fat is exposed to high temperature for any length of time 

 the body will be injured and butter made from such cream will acquire a 

 body similar to that of renovated butter. That kind of butter will sell below 

 quotation, and the operator is apt to decide that pasteurized butter will 

 not be a success. It must be fully understood that whenever we want to 

 pasteurize cream for butter making we must invest money in a pasteurizer, 

 as the can system will always be a failure. 



All manufacturers of pasteurizers use every effort to make the best 

 on the market and one that can be operated with the greatest possible 

 degree of economy. They are fitting them with stirrers of various con- 

 struction. These are to make the milk move rapidly over the hot surface 

 with the object of having it thoroughly mixed, and to prevent it from 

 burning on the sides of the machine. They also aim to have the cream 

 exposed to the high temperature only a short time and then cooled im- 

 mediately so as to prevent any injury to the body. 



Experiments conducted at the Royal Experiment Station at Copen- 

 hagen prove that if a pasteurizer is properly constructed and properly 

 operated it will require about ninety pounds of steam for heating 1,000 

 pounds of milk from 90 to 185 degrees Fahrenheit. If we figure that it takes 

 one pound of coal to produce four pounds of steam, to produce ninety 

 pounds of steam will then require twenty-three pounds of coal. Figuring 

 coal at $4.00 per ton, and our butter yield four and one : half pounds of butter 

 to 100 pounds of milk, makes the cost of pasteurizing one pound of 

 butter about one-tenth of a cent. This expense however is reduced con- 

 siderably by pasteurizing the cream and skimmed milk separately. The 

 cream is reduced to such a small amount that the expense per pound will 

 be very little. For pasteurization of skimmed milk the exhaust steam 

 can be used. This is also more satisfactory to the patrons as milk when 

 pasteurized after skimming is warm enough to scald the cans and the milk 

 keeps sweet longer. 



Regarding the efficiency of continuous pasteurizers Mr. Monrad in 

 his book on "Pasteurization" quotes the following from Dr. Eaton. "The 

 efficiency of the continuous pasteurizer is very likely due to the extremes 

 in temperature, to the rapidity with which the heat is applied and to the 

 sudden cooling of the milk." The same author quotes from Dr. Stohman: 

 "The killing of the bacteria will be promoted through the sudden change of 



