476 EXPERIMENT STATION EECORD. 



The greatest loss ^Yas found to occur after 10 days' storage and to continue 

 thereafter. This decrease did not depend so much upon the duration of the 

 storage i)eriod as upon the physical character of the cheese and the temperature 

 of the room. After 15 days' storage the fat diminution varied from 1.04 to 5 37 

 per cent, and after 40 days from 6.2S to 11.76 per cent. The fat loss depended 

 largely upon the extent of the mold formation, for as this proceeded and covered 

 the surface the amount of fat removed from the cheese was increased. Mold 

 foiTuation ordinarily began after 10 days' storage and increased thereafter. 



The fat loss was practically as great when the cheese was thinly coated with 

 pai'atHn as without. However, if the cheeses are dipped repeatedly in the 

 paraffin bath from the beginning of the experiment the fungus makes very little 

 growth during the storage and the decrease in fat is much less. The formation 

 of mold could not be completely restrained by the paraffin method. 



The ripening process and the loss of fat were found to be two wholly inde- 

 pendent processes, for the ripening of cheese was as effective in the absence of 

 oxygen-containing air as in ordinary air, but in the former no loss of fats 

 occurred. The characteristic feature of ripening cheese is the cleavage of the 

 casein into the albumoses and peptones, and finally into the amino acids, such 

 as leucin, tyrosin. etc. The extent of this cleavage dei)ends upon the quantity 

 of preciiJitable and unprecijiitable nitrogen present. In the ripening pi'ocess the 

 presence of the aerobes was found to be indisi)ens;ible, while that of the anae- 

 robes is yet an unsettled question. 



In conclusion, it is stated that in the ripening process of cheese under no 

 circumstances is there an increase of fats, much less a building up of fats out 

 of the proteins. The amount of fat is determined b.v the growth of a vegetable 

 mold on the surface of the cheese during the ripening process, and it remains 

 wholly unchanged if riiioned in an oxygen-free room. 



Bacteria concerned in the production of the characteristic flavor in cheese 

 of the Cheddar type, Alice C. Evans, E. G. Hastings, and E. B. Hart (U. S. 

 Dept. Agr., Jour. Agr. Research, 2 {1914), No. 3, pp. 167-192) .—This work was 

 in cooperation with the Wisconsin Station. The authors summarize the re- 

 sults as follows: 



" Tlie organisms constantly found in Cheddar cheese in such numbers as to 

 indicate they must function in the ripening process are included in four groups: 

 First, the Bactrriinti lactis ncidi; second, the B. r-a.sei ; third, Streptococcus; 

 fourth. Micrococcus. On the basis of the fermentation powers each of the four 

 groups may be divid(>d into a number of varieties. The distribution of tlie 

 varieties of the four groups in Cheddar cheese prepared from raw milk has been 

 studied, as has also been done with cheese prepared from pasteurized milk. 



" The flora of raw-milk cheese is varied and consists of all the varieties into 

 which the four groups were divided. The flora of pasteurized-milk cheese, with 

 the exception of tlie B. ca.'^ei group, is dependent upon the flora of the starter. 

 The B. casei group is apparently responsible for tlie pungent taste that develops 

 late in tlie ripening period of both raw-milk and pasteurized-milk cheeses. It 

 is probable that growth of this group continues during the major part of the 

 ripening period. 



" The action of two or more organisms growing together is not the sum of 

 their individual actions when growing alone. When growing together, they 

 may attack substances that neither can attack alone, or they may produce a 

 larger quantity of acid than the sum of the quantities that either can produce 

 alone. When added to pasteurized milk, the organisms of tlie B. casri group 

 produce a sour taste in the cheese during the early jiart of the ripening period. 

 No Cheddar flavor is obtained in pasteurized-milk cheese when the organisms 

 of the B. Metis aeidi group alone are used as starters. The varieties tliat are 



