PASTEURIZATION. 177 



than .4 percent of viseogen in cream of good flavor 

 and high acid, and not more than ^/^ per cent of vis- 

 cogen in off flavored cream. Too much viscogen in 

 cream kills the aroma and flavor in the butter made 

 from it, and imparts a peculiar limy flavor to it. 



225. Object of pasteurization. In pasteurizing -we 

 aim to destroy all lactic acid producing bacteria and 

 as many other kinds of bacterial life, the thermal 

 death point of which comes within the range of the 

 heat applied. By destroying practically all abnormal 

 fermentations and disease producing germs the 

 cream is rendered comparatively free from germ life 

 and in this condition the cream is in the best possible 

 shape for controlling lactic acid fermentation and 

 producing a high grade of butter. (Conn.*) 



226. Heating and cooling. When using a continu- 

 ous machine the cream may be heated to 190° F. 

 without injuring the flavor of the butter made from 

 it or increasing losses in the buttermilk. The poorer 

 the flavor of the cream the higher should be the tem- 

 perature used in pasteurizing unless this cream has 

 been heated in a separate tank to a temperature of 

 about 125° F. and thoroughly stirred for the purpose 

 of removing bad odors. After pasteurizing, the cool- 

 ing must be rapid and thorough. The cream should 

 be cooled to ripening temperature unless it is rich 

 enough to allow the addition of 30 per cent or 40 per 

 cent of starter. If this is possible the cream should 

 be cooled to below 53° F. and held at a low temper- 

 ature until churning time. When thin cream is pas- 

 teurized and is to be ripened, it should be cooled to 



' Conn. H. W. Bacteria in Milk and its Products, 1903 ; Chapter 7, 

 pages 208, 213, 226, 228. 



