DETERMINING QUALITY OF MILK FOR CONDENSERIES. 5 



any manner to reduce the extreme lumpiness. Some of the samples 

 of low acidity showed as objectionable a curdiness as those of the 

 higher acidity, indicating the reliability of the alcohol test and un- 

 reliability of the acid test in picking out those which will not stand 

 the sterilization necessary in manufacturing evaporated milk. 



The table shows also the result of sterilization upon 45 samples of 

 milk of varying acidity, all of which showed a negative reaction with 

 75 per cent alcohol. Forty-two of the 45 when evaporated and 

 sterilized showed no curdiness after shaking. 



Table 1.- — Comparison of alcohol and acid tests at Grove City creamery. Milk 

 concentrated 2\ to 1 and sterilized at 235° F. for 30 minutes. Effect of sterili- 

 zation noted after shaking for 1 minute. 



Acidity. 



Coagulation with 75 per 

 cent alcohol. 



No coagulation with 75 

 per cent alcohol. 



Total 

 samples. 



Effect of steri- 

 lization. 



Total 

 samples. 



Effect of steri- 

 lization. 



Curdy. 



Not 



curdy. 



Curdy. 



Not 

 curdy. 



Per cent. 

 0. 14 to 0. 15 

 . 15 to . 16 

 . 16 to . 17 

 . 17 to . 18 

 . 18 to . 19 

 . 19 to . 20 

 . 20 to . 21 



Total.... 



3 

 5 



10 

 11 

 10 

 5 

 1 



3 

 5 

 8 

 11 

 10 

 5 

 1 





 

 2 

 

 

 

 









1 

 9 

 12 

 11 

 10 

 2 





 

 1 

 1 

 

 1 



1 

 9 

 11 

 10 

 10 

 1 



45 



43 



2 



45 



3 



42 



It seems quite certain that there is some condition of raw milk 

 coagulating with 75 per cent alcohol, making it impossible to sterilize 

 without getting a curdy finished product, for such milks when evapo- 

 rated and sterilized give a much firmer coagulation than those show- 

 ing a negative reaction with 75 per cent alcohol. In some instances 

 the coagulation, even at the lower temperatures used, is such that the 

 product turns to a hard, cheesy mass incapable of improvement with 

 long-extended shaking. Figure 1, showing the type of curd ob- 

 tained in sterilization, indicates clearly the difference which must 

 exist in the condition of milk coagulated with 75 per cent alcohol. 

 Only 6.7 per cent of the samples made from milk coagulating with 

 alcohol gave a soft curd, the remainder giving either a firm or a hard 

 curd, both of which are as a rule difficult to shake out to give a 

 product showing no curdiness. With the evaporated samples from 

 raw milk not coagulating with 75 per cent alcohol 88.9 per cent gave 

 either a soft curd or no coagulation at all, the remaining 11.1 per 

 cent giving a firm curd. The soft curds shake out very easily, giv- 

 ing a smooth-bodied product of good consistency showing no curdi- 

 ness. 



