248 



CREAM RIPENING 



Table 42. Standard Per Cent Acid in Cream of Varying Rich- 

 ness, Number Cubic Centimeters of N/10 Normal Alkali Solution 

 Needed When 50 c.c. and 18 c.c. of Cream Are Used, and Acidity 

 in Terms of Degrees. 



The true lactic acid bacteria of cream ripening require the 

 presence of oxygen for their development, they are aerobes. 

 During the process of ripening, or of changing a portion of the 

 milk sugar to lactic acid, they use up most of the free oxygen 

 in cream. Overripened cream is a medium .practically devoid 

 of free oxygen and favorable particularly to anaerobes, those 

 species of bacteria, which thrive best in the absence of oxygen, 

 and also to yeast and molds. Some of the most common of these 

 anaerobic species of bacteria belong to the putrefactive type, de- 

 composing the proteids and possibly splitting the fats, and gen- 



