«22 ANNUAL REPORT OF THE Off. Doc. 



(2.) Changes in the Paracasein, — In freshl}' coagulated cheese-curd, 

 the milk-casein has been changed to ijaracasein, and, with the forma- 

 tion of lactic acid in cheese, the paracasein unites with the acid 

 forming a «ew compound. Fresh cheese has always been supposed 

 to consist entirely of paracasein, except for the fat, moisture and 

 salt. It has recently been discovered in the laboratory of the New 

 York (Geneva) Agricultural Experiment Station that fresh or green 

 cheese instead of containing paracasein, contains the lactic acid com- 

 pound of paracasein. Now this compound undergoes changes in the 

 course of ripening, which greatly change the whole character of the 

 cheese. Green cheese is tough, somewhat rubber-like, not appre- 

 ciably soluble on the tongue, difficult of digestion, and lacking 

 flavor. In the course of ripening, the cheese becomes more or less 

 soft, more easily digestible and acquires characteristic flavors. A 

 piece of well-cured cheese, when placed on the toogue, should dis 

 solve somewhat like a piece of cold butter, leaving no trace of harsh 

 or gritty-feeling particles. Just how the flavor is produced or where 

 it comes from we do not know with certaintv. In normal cheese- 

 ripening, the fat undergoes little or no change. The curing process 

 in cheese involves the change from unmarketable to marketable 

 conditious. The exact causes of these changes are not clearly known 

 yet; it is probable that they are due to the combined action of ga 

 lactase, the enzyme in milk, to the pepsin enzyme in rennet, and to 

 certain forms of bacteria. 



62. Temperature for Curing Cheese. 



It has been found that cheese cures more quickly at higher tern 

 peratures and that, above certain temperatures, the texture and 

 flavor are unfavorably affected. It was formerly thought that a 

 temperature of 70 degrees F. was about right for best results. But 

 it is now known that a temperature of 55 degrees F. or 60 degrees 

 F. gives very much better results, and it is thought that a tempera- 

 ture as low as 40 degrees F. may be still better. Cheese cured at 

 75 degrees F. or above will suffer more or less from leakage of fat. 

 It may be said with positiveness that cheddar cheese cured above 

 60 degrees F. does not give cheese of the best quality, either in 

 respect to general character or in respect to keeping qualities. 

 Cheese cures more slowly at lower temperatures, but the product 

 is superior in quality. In addition, at low temperatures, less moist- 

 ure is lost and one has more pounds of cheese to sell. 



63. Moisture in Air for Curing Cheese. 



The relative amount of moisture in air can be shown by ao instru- 

 ment (see Fig. 7), called a hygrometer, or hygroscope, which can be 



