611 



homemade rennet extracts; and (5) general changes in composition 

 whieli take place in the rii)ening or cnring- of cheese. 



By way of introduction the composition of milk and cheese and the 

 processes of the manufacture of cheese are popularly discussed. 



Nine separate experiments were made, eight at the station and one 

 at the factory. Six of these were in making stirred-curd cheese and 

 three Cheddar cheese. " The milk used was mixed milk of various 

 breeds of cows. In some cases it consisted of milk from 2 or 3 days' 

 railkings, but in most cases it consisted mainly of fresh morning's 

 milk mixed with the milJv of the previous evening." In the different 

 trials milk was used containing from 2.35 to 6.49 per cent of fat, the 

 desired percentage of fat being secured by skimming or by adding 

 cream. Tiie details of cheese making were varied as to temperature, 

 time allowed for the separate processes, the kind of rennet used, etc. 



In each experiment the cheese was made by an experienced cheese 

 maker. Analyses were made at the station of the milk; the first, .sec- 

 ond, and third wheys; and of the cheese when 7, 21, and 35 days old, 

 respectively. Incidentally it is mentioned that i'or the determination 

 ot the fat in cheese the Babcock test did not give sufficiently accurate 

 results and was discarded for gravimetric methods. The tests of the 

 milk and whey Avere by the Babcock method. 



l-'ull details are tabulated of the process of manufacture, the analyti(5al 

 results, and the yield of cheese. Without going iiito details, the general 

 results obtained are summarized below under different headings. 



Losx of fat , raKviii. and allnimcii in cheese making. — The actual aiuomiti, as well as 

 the pr<>i»oitioii, of milk fat Inst in the whey increased gradually, but not unitoniily, 

 when the anu)unt of fat in tlie milk increased. 



The average amount of fat lost in the whey in all the experiments was altout one 

 third of a pound for 100 pounds of milk, which was about 7.5 per cent of the milk 

 fat. Talking only those experiments Avhich most nearly represented average factoiy 

 milk, the average amount of milk fat lost was one fourth of a pound for 100 pounds 

 of milk, which was nearly 7 per cent of the milk fat. 



Wliile it Avas true that the loss of fat increased, both absolutely and relatively, 

 when the amount of fat in the milk increased, it was not trne that all the additional 

 fat above 4 per cent or even above 5.5 per cent was lost in the whey. * * * 



In the comparison -.nade between the stirred-curd and Cheddar processes, the 

 amount of fat lost in the third and fourth exjieriments is practically the same, the 

 fat in the milk being 3.88 and 3.96 per cent, respectively. In the fifth, sixth, and 

 seventh experiments, when the fat in the milk was about the same, being between 

 4.7 and 4.8 per cent, the Cheddar process gave considerably better results. That the 

 difference in favor of thi- Cheddar jirocess in this case was due to the Cheddar proc- 

 ess we can not say; changes due to other conditions in the process of mannfa<ture 

 may have made the difference. Before we can draw any definitt; conclusions in 

 regard to loss of fat in the Cheddar process as compared with the stirred-curd, many 

 other experiments will be needed. * * * 



The amount of casein and albumen lost appeared to bt-ar no definite relation to the 

 total amount of casein and albumen in the milk. 



The average amount of casein and albumen in the milk in the eight experiments 

 was 3.43 pounds per 100 pounds of milk; of this amount about 23 per cent or about 

 0.8 pounds was lost. 



