DAIRY FARMING DAIRYING. 1005 



])ractically all converted into the dilactate. In one experiment the casein monolac- 

 tate in milk l)efore coap;alation was visible amountetl to 65 per cent of the casein. 

 No (lilactate was then present. 



In stndying cottage cheese attention was paid to the relative amomits of monolactate 

 and dilactate jn-esent, the conditions nKJst favorable for the manufacture of such 

 cheese, the manufacture of cottage cheese with artificial acids, the question of the 

 occurrence of a ripening process such as takes place in Cheddar cheese, and the 

 digestiV)ility of cottage cheese in pepsin solutions. The experimental work is 

 reported in detail, and is summarized in essentially the form given l)elow. 



" Yield and composition of cottage cheese. — The yield of cheese from 20.5 lbs. of milk 

 varied from 3.56 to 4.63 lbs. under the conditions tried. The moisture in cheese 

 varied from below 70 to over 80 per cent. The variation in moisture accounts largely 

 for the variation in yield. The amount of moisture in cheese is dependent upon the 

 trmjierature used in curdling the milk and in heating the curd to expel moisture 

 and also on the length of time the curd is heated. Cottage cheese of the best texture 

 should contain 70 to 75 per cent of moisture. Best success was attained when milk 

 was soured and curdled not much above 70° F. (21° C.) and the subsequent heating 

 was not carried above 90° F. (32° C.) . Milk sugar in the cheese varied from 3.28 to 

 4.08 per cent, which is equivalent to 10 to 16 per cent of the sugar originally present 

 in the milk. Of the sugar in the milk 23 to 27 per cent was decomposed in the 

 souring. Nitrogen in cheese is mostly in the form of casein dilactate, equivalent to 

 2 to 2.5 per cent of nitrogen. 



"■Manufacture of cottage clieese Juj direct addition of an artificial acid to milk. — Milk 

 was coagulated by addition of lactic acid and hydrochloric acid and the curd made 

 into cottage cheese. Satisfactory results in every respect were secured. For exam- 

 ple, hydrochloric acid (sp. gr. 1.20), diluted with 10 times its volume of water, was 

 added to milk in the proportion of 8 ounces for 100 lbs. of milk at 75° F. (24° C.) 

 and stirred vigorously. The curd separated at once in flocculent form and was 

 strained from the whey without further heating. Any absence of sour-milk flavor 

 can be supplied by mixing with the cheese some ripened cream. Cheese made in 

 this way contains more milk sugar and more nitrogen than cheese made by the 

 ordinary method of souring milk. 



^'Slight change cjf insoluble into soluble nitrogen compounds in cottage cheese. — Cottage 

 cheeses were made by ordinary souring method from whole milk and from pasteur- 

 ized and unpasteurized skim milk, with and without rennet, and. were examined at 

 intervals to ascertain to what extent insoluble nitrogen compounds change into solu- 

 ble ones, as in the case of Cheddar cheese. Such proteolytic changes as occurred in 

 2 to 3 weeks were insignificant. 



'^Artijicicd digestion of some compounds of casein and paracasein contained in cottage 

 cheese. — According to popular l)elief, fresh cottage cheese is more readily digested 

 than Cheddar cheese. To test this by laboratory methods, we have su])jected to 

 pepsin digestion, without hydrochloric; acid and with hydrochloric acid in varying 

 pioi)ortions, fresh cottage and Cheddar cheese, in which we had one or more of the 

 folhjwing substances: Paracasein, ])aracasein monolactate in Cheddar cheese, para- 

 casein dilactate, casein monolactate, casein dilactate (cottage cheese) prepared by 

 normal souring of milk and also by direct addition of lactic acid to milk, and casein 

 dihydrochlorid. In the absence of acid, paracasein fails to be digested by pepsin, 

 while paracasein monolactate (the chief nitrogen compound of fresh Cheddar cheese) , 

 ]iaracasein dilactate, casein monolactate and casein dilactate (cottage cheese) are par- 

 tiallv <ligested. Paraca.'^ein monolactate and casein monolactate, in the absence of 

 acid, are dig:ested more than are ))aracasein dilactate and casein dilactate. In the 

 [iresence oi 0.4 per cent of hydrochloric acid, paracasein dilactate is digested by pep- 

 sin more than is paracasein monolactate. Paracasein monolactate and dilactate and 

 ca.sein monolactate and ililactate and casein dihvdrochlorid digest more readilv and 



