60 REPORT OF THE No. 55 



contained in the raw product. For this determination ordinary raw milk contain- 

 ing in the neighbourhood of 3,000,000 bacteria shall be used and the pasteurized 

 product shall be collected as it flows from the cooling apparatus. 



All continuous pasteurizers shall be equipped with a feeding pipe which is so 

 constructed that the pasteurizer cannot be fed in excess of its normal working 

 capacity; that is, in excess of the working capacity of the machine at which 99 

 per cent, of the bacteria are killed when the required amount of heat is applied. 



All continuous pasteurizers' operated outside of the city limits, for the produc- 

 tion of pasteurized milk and milk products to be sold in the city of Chicago, shall 

 be equipped with an apparatus regulating automatically the supply of steam and 

 heat, so as to correspond with and produce the required temperature of the out- 

 flow of the pasteurized product. These automatic thermo-regulators shall be accur- 

 ate and must be approved by the Commissioner of Health before being installed. 



A recording apparatus shall be installed upon all continuous pasteurizers oper- 

 ated within the city limits so as to record during operation the temperatures of the 

 pasteurized product as it flows from the heater. The thermometer of this record- 

 ing apparatus must be accurate and kept emerged in the milk in such a way tint 

 it is not exposed to escaping steam or other heat, except the heated milk. 



The records made by this recording thermometer must be accurate and made 

 in a chamber which is kept under lock and key in the control of the Department 

 of Health. 



The automatic thermo-regulating and recording apparatus may be combined 

 into one instrument and it is recommended that all pasteurizers be equipped with 

 both appliances or combination apparatus. 



(B) (Held Pasteurization.) Whenever milk is held during pasteurization in 

 such a manner that the process of pasteurizing is not a continuous one, namely, a 

 continuous flow of milk through the heating or heat-retaining chamber., the pro- 

 cess shall be designated as "Held Pasteurization. " Such methods of pasteurization 

 and pasteurization appliances or systems installed and used shall be examined and 

 approved by the Commissioner of Health, or his duly appointed representatives, 

 when all of the following requirements are fulfilled: 



1. When the pasteurized product shows that over 99 per cent, of the bacteria 

 and all pathogenic bacteria contained in the raw product have been destroyed. 



2. When the mechanism of the pasteurizer or pasteurizing system is such that 

 the three important elements, namely : the temperature, time of exposure, and the 

 quantity of milk exposed at one time, can be readily kept under control and obser- 

 vation by the Department of Health. 



3. When the following conditions are complied with: 



A uniform heating of 140 degrees F., maintained for 20 minutes ; 150 degrees 

 F., maintained for 15 minutes; 155 degrees F. maintained for 5 minutes; 160 de- 

 grees F., maintained for I 1 /? minutes; 165 degrees F., maintained for 1 minute. 



The time shall be calculated from the period that the entire quantity reaches 

 the required temperature. 



Rule 7. (Cooling Temperatures.) The pasteurized product shall be cooled at 

 once to a temperature of 45 degrees F. or less. This cooling shall be so conducted 

 that the pasteurized product is not exposed to the air or other contamination. This 

 cooling apparatus shall be so constructed that it can be readily cleansed and steri- 

 lized- 



