248 BIOLOGICAL ACTIVITIES OF MOLDS 



ture of proteolytic enzymes (proteinases, polypeptidases, dipepti- 

 dases), may be obtained from certain strains of the A. flavus-Oryzae 

 group. They are used in the manufacture of glue, degumming silk, 

 in dehairing and bating of hides, in making chill-proof beer, and so 

 on. Pectinase, an enzyme hydrolyzing pectin, may be obtained from 

 certain strains of Penicillium and is used in clarifying certain fruit 

 juices. 



USE OF MOLDS IN FOOD PRODUCTS 



The ripening processes used for certain cheeses such as the Roque- 

 fort type (Roquefort, Gorgonzola, Stilton, American Blue-veined), 

 Camembert, and Brie are dependent largely on the metabolic activi- 

 ties of certain molds. 



In the preparation of Roquefort cheese, a friable, hard curd cheese, 

 the proteins of the milk are coagulated by a preliminary lactic acid 

 fermentation (carried out by Streptococcus lactis) and the addition 

 of rennet. After the curd has set, it is cut into small sections to 

 allow the whey to drain. Penicillium roqueforti is grown on rye 

 bread and the entire moldy mass dried and powdered. This powder 

 is then sprinkled in with the curd as the latter is placed in sterilized 

 hoops. The curd is mechanically perforated to allow sufficient aera- 

 tion for the growth of the mold. The ripening process which re- 

 quires from 5 to 6 months takes place under carefully controlled 

 conditions of temperature and humidity. Salt is periodically applied 

 to the surface of the ripening cheese to cut down the population of 

 undesirable microorganisms. P. roquejorti develops through the 

 cheese, particularly around the holes that have been punched in 

 the curd. It is believed that its lipolytic activities in forming caproic, 

 caprylic, and capric acids or their derivatives are responsible for the 

 development of the desirable aroma and flavor. In the original 

 Roquefort method ewe's milk was used but the Roquefort-type cheese 

 on the American market, at least, is prepared from cow's milk. 



Camembert cheese, a soft curd-type cheese, is ripened by the use 

 of P. camemberti. The curd is first produced by the action of rennet, 

 not as much whey being allowed to drain out as with the Roquefort- 

 type cheese. The curd is placed in rather small forms because the 

 ripening process depends very largely on the diffusion of enzymes 

 from the surface (where the mold develops) to the interior, and 

 the ripening period would be prolonged with larger cheeses. The 

 mold is, as with the Roquefort-type cheese, grown on bread which is 

 then dried and powdered. The mold product is dusted upon the 

 surface of the curd which is then allowed to ripen under controlled 

 conditions of temperature and humidity. The Penicillium grows 



