136 THE BOOK OF CHEESE 



ripening room held between 50 and 60 F. with humidity 

 so high that evaporation is kept at a minimum. In this 

 room, a surface slime develops quickly. This consists 

 of bacteria of several forms, yeasts, Oidium lactis and 

 accidental species of other molds'. During this ripening, 

 the cheeses are turned, rubbed with the hands, washed 

 with salt water and scraped if infected with molds which 

 produce colored colonies. In the course of ripening, the 

 slimy surface layer acquires a yellowish orange color 

 with the strong odor and taste characteristic of the series. 



Brands of d'Isigny are made from every grade between 

 separator skim and whole milk. They reach the market 

 in' condition all the way from "Kosher" forms 1 which 

 are eaten entirely unripe, to brands which approximate 

 the qualities of Limburger and others which approach 

 Port du Salut. 



The biology and chemistry of the ripening of this type 

 of cheese have not been completely followed. An initial 

 souring process always takes place quickly. Oidium 

 lactis is always present in some degree on the surface, 

 but the organisms in the yellowish to orange slime on the 

 surface of the cheese appear to produce the characteristic 

 odor and taste. These appear to be due to the develop- 

 ment of volatile fatty acids, such as valerianic and ca- 

 proic, which diffuse throughout the cheese, even pene- 

 trating the unripened sour portions. The same odor 

 and taste in varying intensity are present in Limburger, 

 Brick, and a long series of German varieties not handled 

 in America. 



High-flavored cheeses such as these, form an acceptable 

 part of the meal in cases in which the intensity of other 



1 Kosher forms are prepared in compliance with the Mosaic 

 law as demanded by the Jewish trade. 



