234 CREAM RIPENING 



and that the extent of this chemical change is directly propoi- 

 tional to the quantity of acid present in the cream from which 

 the butter was made." 



In the presence of the above facts it appears safe to con- 

 clude that the ripening of cream does not enhance the keeping 

 quality of butter, that the churning of sour cream is distinctly 

 injurious to keeping quality, that butter that is not consumed 

 soon after it is manufactured, or butter intended for storage 

 purposes, should be made from unripened cream or from cream 

 in which the acidity is low, and that cream ripening is justifi- 

 able only in the case of butter that is intended for immediate 

 consumption. 



Natural Ripening of Cream. The natural ripening of cream 

 consists of allowing the cream to sour without the addition of a 

 starter. This is the oldest method of cream ripening, the cream 

 is held at a temperature favorable for bacterial action until it 

 is sour. The character of fermentation which occurs and the 

 quality of the resulting butter depend largely on the bacterial 

 flora of the cream after it leaves the separator, or after it ar- 

 rives at the creamery and this in turn will depend on the sani- 

 tary care which the milk and cream receive on the farm, on the 

 age of the cream and on the particular types of bacteria which 

 may predominate in any given locality and at any given season 

 of the year. With cream that is clean and that has been produced 

 under highly sanitary conditions, natural ripening may produce 

 very good butter. Where little or no attention is given to clean- 

 liness, contamination of the cream with relatively large num- 

 bers of undesirable species of micro-organisms is unavoidable. 

 When such cream is allowed to 'ripen in the natural way, un- 

 desirable fermentations are prone to gain the ascendency, re- 

 sulting in butter of inferior flavor and low keeping properties. 



Inasmuch as the natural ripening process affords no facilities 

 for controlling fermentations, the product usually also lacks in 

 uniformity of quality. The bacterial flora of the cream varies 

 not only with the individual care which each lot of cream re- 

 ceives on the farm, but also with the season of the year. Thus 

 in early summer when the cows are on pasture, conditions are 

 favorable to a preponderance of lactic acid bacteria to the partial 

 exclusion of peptonizing and putrefactive germs, while in late 



