194 



STATE BOARD OF AGRIC'UL.TURB. 



TABLE NO. III. 



The fact that the milk had a pH score of only 85 after it had been 30 min- 

 utes at 145° indicated fault at this stage, as milk usually shows a better score 

 after holding. An examination of the recording thermometer in use showed 

 that five degrees higher temperature was being recorded than was being 

 applied to the milk. This accounted for the low score after holding. The 

 hour's delay after holding while the milk was being cooled in the pasteurizing 

 vat and while preparations were being made for bottling allowed the pas- 

 teurized milk c^uite a time to stand at a growing temperature during which 

 the score of the milk was lowered to 55. Due to a good brine cooling system, 

 the milk after cooling and bottling maintained the score of 55 until delivered 

 the next day. 



Thinking the chief trouble with the pasteurizing process had been located 

 it was decided to test the process the following day using an actual tempera- 

 ture of 145° F. and passing the held milk immediately over the brine cooler 

 in order to do away with the milk standing at an incubation temperature so 

 long. The results are shown in Table No. IV. 



TABLE NO. IV. 



pH score. 



1. Raw milk, pasteurizing tank 



2. Heated to 145 F 



3. Milk held at 145 F. for 30 minutes 



4. Immediately over cooler to bottle. . . 



45 



55 



100 



100 



The above table shows that the trouble with the pasteurizing process was 

 as indicated in Table No. Ill and easily remedied. 



Unfortunately this plant has such an inadequate water supply that it 

 isn't practical to treat the milk as shown in Table IV. The brine cooler and 

 the spray vat cooler cannot be operated simultaneously for lack of water. 

 However, this plant is about to move into a new specially constructed build- 

 ing and this difficulty will be ended. 



Four thousand one hundred twenty quarts of milk sold in Ypsilanti l^y 15 

 dealers is from 37 farms and amounts to a per capita consumption of about 

 0.9 pints. Approximately 46 per cent of this is pasteurized by the one pas- 

 teurizing plant. 



The writers suggest that in the future it be made more difficult for those 

 desiring to sell milk in the city to obtain a license. It would be an easy mat- 

 ter to make those desiring to sell milk in the city come up to requirements as 

 to equipment and methods. It is very difficult to bring al)out improvement 

 in plants now existing. 



Some arrangement should be made for laboratory examination of samples. 



