DETERMINING QUALITY OF MILK FOR CONDENSERIES. 3 



it is considered unsafe from the standpoint that the milk after 

 evaporation will not stand the heat necessary for sterilization with- 

 out becoming curdy. The test is practical and easy to make at the 

 weigh room. The test as used in this work was made by adding 

 1 c. c. of milk to a small test tube containing 1 c. c. of alcohol and 

 mixing at once by inverting once or twice while holding a finger 

 over the top. Any reaction that takes place will be very quickly 

 evident, the large majority of tests showing coagulation immediately 

 or giving no reaction at all. The gradation of coagulation is shown 

 by the size of the curd particles formed. Unless the curd particles 

 formed are small the reaction is not at all difficult to distinguish, 

 even by one not familiar with the test. A mixture of milk and 

 alcohol giving a negative reaction immediately breaks clear from 

 the walls of the test tube, while a mixture giving a coagulation 

 of fine particles will leave the walls of the test tube cloudy. Mix- 

 tures showing a medium or large particle curd formation are readily 

 discernible because of the adherence of the curd particles to the 

 walls of the test tube. 



In the work of grading the milk at a condensery on a commercial 

 basis two small brass dippers of 2 c. c. capacity each were used. 

 Thirty test tubes arranged in a block of wood 3 inches wide, 2 inches 

 deep, and 18 inches long, having three rows of holes of the proper 

 diameter and depth, were first filled with 2 c. c. of the 75 per cent 

 alcohol by means of one of the brass dippers. Two men working 

 together then went through the individual cans, taking 2 c. c. of milk 

 from each and mixing it with the 2 c. c. of alcohol. No more time 

 was required than is necessary in making the acidity test. 



The first work attempted with the alcohol test was to determine 

 whether any correlation existed between the coagulation and the 

 acid content of milk as measured by the usual titration method. 

 Samples of milk were taken from individual patrons at the weigh 

 room of the Grove City, Pa., creamery for the observations made. 

 Reactions with 75 per cent ethyl alcohol and titratable acidity were 

 determined shortly after taking samples and at stated intervals on 

 those not showing positive coagulation with alcohol, until such action 

 occurred. All samples which did not show coagulation with alcohol 

 at the outset were held in a water bath at 35° to 37° C. (95° to 

 98.6° F.) during subsequent observations. A tabulation of 211 

 samples of milk handled according to the method outlined shows 

 conclusively that there is no direct relation between the coagulation 

 of the milk with 75 per cent alcohol and the acid content of milk 

 as measured by the titration method. 



