CREAM RIPENING 113 



sterilize when the pasteurization is performed in hot 

 water. 



4. Protect the containers with regular covers (caps or 

 tops) . 



5. Pasteurize by heating to a temperature of 180 to 

 200 F. for thirty minutes or longer, and then cool to 

 ripening temperature of 60 to 75 F. Lower tempera- 

 tures are efficiently maintained. Pasteurization may 

 be accomplished by tying a string about the necks of the 

 bottles and suspending them in a pail or vat heated by 

 steam, or in a kettle or dish heated on a stove. If pas- 

 teurization is over a fire, the bottles should not rest on 

 the bottom of the receptacle. Other supports may be 

 used to keep the containers from tipping over. If glass 

 containers are used, the temperature should be raised 

 and reduced slowly in order to prevent breaking. 



6. After pasteurization, the milk is ready for inopulation. 

 Inoculate in a quiet place where the wind cannot blow 

 dirt and bacteria into this clean seed-bed. With dry 

 fingers remove the cover and place it in a clean spot. 

 Pour in all of the commercial culture, or 1 to 10 per cent 

 from the previous day's culture. Then shake or stir 

 carefully in order to distribute the bacteria throughout 

 the inoculated material. The amount of ripened starter 

 for inoculation can be measured accurately in a vessel, 

 such as a sterilized cup or spoon, or it can be determined 

 rather closely by the eye. 



7. Ripen at about 60 to 75 F. The first inoculation 

 from the commercial culture should be ripened at about 

 70 to 85 F. The smaller inoculations require higher 

 temperatures. By experience an operator can soon learn 

 the inoculation and temperature required to ripen his 

 starter in a given time. Usually a 1 to 8 per cent inocu- 



