344 CARE AND RIPENING OF CREAM ON THE FARM 



to three days in cans in cold water, and then about twelve to 

 eighteen hours before the butter is to be made, all the cream to 

 be churned is poured, if possible, into one vat or can, thoroughly 

 mixed, warmed to about 70 degrees in summer or 75 degrees in 

 winter, and left to sour. It should be stirred frequently to pre- 

 vent curd clots from forming in the bottom of the can or vat. 

 When the cream has become somewhat thick and glossy and 

 pours like thick milk gravy it is about ripe enough and should 

 be cooled to about 53 degrees to prevent further rapid growth of 

 the lactic acid bacteria, also to temper the fat that firm butter 

 may be made. After the cream has stood cool for four or more 

 hours it will be ready for churning (Fig. 115). 



If the cream is held for a longer period than about three 

 days there is danger of a bitter flavor and an old cream taste 

 developing. The bitter germ is favored by a temperature 

 between 40 and 50 degrees, but grows slowly. On the other 

 hand, if the cream be warmed to a temperature of 85 or 90 

 degrees it is liable to develop a gassy, foul-flavored condition. The 

 germ that produces gas in milk and cream is usually one of the 

 colon group, which lives naturally in the alimentary canal of 

 cows and other warm-blooded animals. The warmer tempera- 

 ture in cream therefore naturally favors the growth of such 

 bacteria. 



Can cream be ripened too much? Indeed, it can. If the 

 souring temperature, about 70 degrees, be maintained for too 

 long a time the acid will literally kill off the very kind of bac- 

 teria that produced it and the cream will take on an old and a 

 harsh taste. Butter made from such over-ripe cream will not 

 keep as well as that made from cream containing less acid. 



Cream is in best condition to chum well and still produce a 

 good keeping butter when it contains about 0.45 to 0.50 per cent 

 acid, if the cream test 35 per cent fat; or 0.55 to 0.60 per cent 

 acid if the cream contains only about 25 per cent fat. 



Wben the cream has stood warm until sufficiently sour as 

 shown by one of the chemical tests, and the senses, it should 

 then be cooled to a temperature of about 52 or 53 degrees or even 

 lower in summer, or 56 degrees in winter, and held at that tem- 



