THE GENESKE FAEMEE. 143 



BUTTER AND CHEESE MAKING. 





Milk is composed principally of three substances- — curd or casein, butter, and sugar of 

 milk, held in solution by some 87 per cent, of water. The casein is what chemists call 

 a nitrogenous compound, and is precisely similar in composition to white of egg, jiure 

 flesh, the gluten of wheat, &c. The butter and sugar, when pure, contain no nitrogen, 

 and correspond in composition with fat, starch, and other carbonaceous compound^. 



Butter exists in milk as oily globules enclosed bij a film of casein, which beino- 

 specifically lighter than the milk, gradually rise to the surface when allowed to stand. 

 With these globules, or cream, arises a portion of the sugar of milk ; so that in the 

 cream we have the butter and a small amount of casein and sugar. This sugar of milk 

 may be obtained by taking some sweet whey and heating it slightly, adding at the same 

 time a little white of egg. This will precipitate all the curd and butter, which must be 

 removed by filtering through a fine cloth. The whey will be clear and free from all 

 impurities. If it is now poured into an earthen vessel, and placed in a cool place, in a 

 few days small crystals will settle on the sides and bottom of the vessel. These are 

 sugar of milk. This sugar may be preserved dry or in solution for a great length of 

 time. But if into a solution there be placed a little curd or rennet, a chemical action 

 immediately takes place, and the sugar is converted into lactic acid. The same acid is 

 produced in the fermentation of brewers' grains, cabbage, (^Sauer Kraut,) and in a num- 

 ber of familiar instances. If the fermentation be allowed to proceed, carbonic acid is 

 given oft', and alcohol is formed precisely as in the fermentation of cane and grape sugar. 



Now, in the cream we have this sugar of milk in solution in conjunction with curd, 

 the very condition essential to the formation of lactic acid ; and we accordingly find 

 that at the proper temperature for fermentation, (from 60 to 120 deg. Fahv.,) lactic acid 

 is produced, and the cream becomes sour. When cream is heated, the oily globules 

 appear to burst their shells and run into each other, rising to the surface in the form of 

 melted fat. Likewise, when cream or milk is agitated for a length of time by mechan- 

 ical means, the temperature is increased, the films enclosing the globules are broken, and 

 the fatty matter runs together in the form of small grains, and finally into lumps of 

 ordinary butter. The facility with which this is accomplished appears to be greatly 

 promoted by the 2:)resence of the lactic acid, since it never takes place without becoming 

 slightly sour during the process, even though the cream is sweet when put into the 

 churn. It is always advisable to have the cream sour before churning, as much less 

 labor is required, and more butter obtained than when churned sweet. In cold weather 

 it is often necessary to place the cream in a warm place before the fermentation of the 

 sugar will take place ; in other words, before it will sour. 



As the result of many experiments, it is now proved that cream should not be wanner 

 than 55 deg. Fahr. Avhen placed in the churn, nor more than 65 deg. when the butter 

 comes. This temperature produces the greatest quantity and best quality of butter. 

 The cream always increases in temperature from 5 to 10 deg. during churning. 



The composition of butter differs very much, according to the manner in which it is 

 obtained, the kind of cows, quality of food, and time of year. It consists generally of 

 about 84 per cent, of the fat of milk, or pure butter, and 16 per cent, of water, sugar of 

 milk, and casein ; the latter in very small proportion, yet sufficient to produce great 

 changes in the butter, unless means are taken to counteract its transforming influence. 

 We have seen, that in contact with casein, sugar of milk is changed into lactic acid. In 

 butter, therefore, the sugar soon changes into this acid. But that is not all : under the 

 influence of the air, and in connection with butter, further decompositions take place, 

 and bufgric acid is produced, which imparts a very disagreeable odor and taste to the 

 , K butter. If allowed still further to decompose, caprlc and caproic acids are produced ; . - 



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