DAIRY FARMING DAIRYING. 93 



Making, byH. L. Russell (E. S. R.,8, p. 728); Influence of Acid on Texture of Cheese, 

 by H. L. Russell and J. W. Decker (E. S. R., 8, p. 728); Hot-Iron Test, by S. M. Bab- 

 cock (E. S. R , 8, p. 728); Albumen Cheese, by S. M. Babcock ( E. 8. R.,8, p. 728); 

 Print Cheese, by E. H. Farrington (E. S. R., 13, p. 990); Ripening Milk Before Set- 

 ting, by J. W. Decker (E. S. R., 8, p. 730); Effect of Varying Strengths of Rennet in 

 Curdling Milk, by J. W. Decker (E. S. R., 11, p. 580); Action of Rennet in Watered 

 Milk, by J. W. Decker (E. S. R., 11, p. 581) ; Action of Common Salton Rennet Action, 

 by J. W.D ker (E. S. R., 11, p. 584); Effect of Salt upon Cheese, by J. W. Decker 

 (E. S. R.,8, p. 342), and Methods of Handling Sour Milk in Making Cheese, by 

 J. W. Decker ( E. S. R., 11, p. 585). 



Bacteriology of cheese ( Wisconsin Sta. Rpt. 1908, -pp. 226-230). — This is a sum- 

 mary of the following articles: Gas-Producing Bacteria and Their Relation to Cheese, 

 by H. L. Russell ( E. S. R., 8, p. 730) ; Rise and Fall of Bacteria in Cheddar Cheese, by 

 H.L.Russell (E. S. R.,'9, p. 586); Pure Lactic Acid Cultures in Cheese Making, by 

 H. L. Russell (E. S. R., 9, p. 587), and Effect of Digesting Bacteria on Cheese Solids, 

 by ILL. Russell and V. H. Bassett (E. S. R., 12, p. 89). 



Investigations regarding the curing of cheese ( Wisconsin Sin. Jipt. 1903, pp. 

 193-2 00) . —This contains a summary of the following articles previously published 

 by the station: Unorganized Ferments of Milk; a New Factor in Cheese Ripening, by 

 S. M. Babcock and H. L. Russell (E. S. R., 10, p. 785); Action of Proteolytic Fer- 

 ments on Milk with Special Reference to Galactase, the Cheese-Ripening Enzym, by 

 S. M. Babcock, H. L. Russell, A. Vivian, and E. G. Hastings (E. 8. R., 12, p. 87); 

 Influence of Galactase on Ripening of Cottage Cheese, by S. M. Hal nock, H. L. 

 Russell, and A. Vivian( E. S. R., 12, p. 88) ; Influence of Rennet on Cheese Ripening, by 

 S. M. Babcock, H. L. Russell, and A. Vivian (E. S. R., 13, p. 87), and Influence of 

 Varying Quantities of Rennet on Cold Cured Cheese, by S. M. Babcock, II. L. 

 Russell, A. Vivian, and U. S. Baer (E. S. R., 14, p. 1012). 



Some general conclusions regarding causes operative in Cheddar cheese ripening are 

 stated as follows: "The earlier views as to the action of bacteria referred the main 

 part of the work of digestion to the activity of liquefying bacteria. These organisms 

 are capable of producing proteolytic enzyms, which digest the casein of milk with 

 the formation of decomposition products, ranging from albumoses to the more ulti- 

 mate product, ammonia. Numerous observations show that this type of bacteria 

 occurs only sparingly in ripening Cheddar cheese, and it is difficult to believe that 

 the exceedingly small quantities of digestive enzyms which would be produced can 

 exert any considerable influence in the ripening process. 



"As a normal cheese ripens, ammonia is always found, and the origin of this sub- 

 stance can not be attributed to either galactase or pepsin. Hence it seems probable 

 that the activity of living organisms must be invoked to explain the origin of this 

 product, but with the data at hand we are unable to state definitely what types of 

 organisms are concerned. 



"From our present knowledge the factors above mentioned are the chief agents 

 which are operative in the ripening changes that occur in cheese. The initial 

 changes are inaugurated by the lactic-acid bacteria which produce acid that unites 

 with the paracasein forming a compound, paracasein monolactate, soluble in dilute 

 salt solutions. This acid also supplies, even when combined with casein, the optimum 

 conditions for the peptic digestion produced by rennet. 



"The activity of galactase is undoubtedly operative from the beginning and con- 

 tinuous throughout the life of the cheese. The same is true of the pepsin in the 

 rennet extract, which under certain conditions is probably the main factor in break- 

 ing down the casein of the cheese. It is exceedingly difficult, however, to assign 

 to each of these agents the exact amount of proteolytic activity which it performs. 

 Undoubtedly, the effect of environmental conditions (variation in acidity, tempera- 

 ture, etc.) determine somewhat the relative value of each. 



