STARTERS 229 



According to Hammer, the lactic acid, which is non-volatile, 

 produces an acid flavor but very Uttle of the flavor and aroma so 

 characteristic of a good, welhripened cream and the butter made 

 from it. The organisms which he has found to be the most 

 suitable associate organisms of the lactic acid organism {Strep- 

 tococcus lacticus) are Streptococcus citrovorus and Streptococcus 

 paracitrovorus. S. citrovorus acts upon the citric acid of milk 

 and cream (hence its name), and also to a certain extent upon the 

 lactic acid, and converts these into volatile, flavor- and aroma- 

 producing acids. 5. paracitrovorus, in addition to perfomiing 

 the same function, also develops and uses another product. 



A good starter is one which will develop a fair projiortion of 

 the volatile, flavor- and aroma-producing acids without the 

 development of an excess of acidit}'; that is, it wiH afford all the 

 atlvantages to be gained from the proper ripening of cream without 

 the disadvantages that come from ripening it to too high a degree 

 of acidity. The great problem is that <jf the maintenance of a 

 proper balance between the lactic acid organism iS. lacticus) and 

 the associate organism or organi.sms which develop the volatile, 

 ila\'or- and aroma-producing acids. One of the large factors in 

 maintaining this balance is a proper ripening temperature in 

 both starter- and cream-ripening. Hammer mentions 70-72° F. 

 as a very favorable range. A temperature much abo\'e this is 

 more favorable to S. lacticus than to 5. citrovorus, that is, it will 

 enhance the development of lactic acid to a greater extent than 

 that of the flavor- and aroma-proclucing acids, and throw the 

 ripening out of balance. 



It would seem then that the big problem for our laboratories, 

 in the preparation of commercial cultures, is to supply a culture 

 which, if properly handled in the creamer}-, wifl develop a reason- 

 able amount of suitable, volatile flavor- and aroma-producing 

 acids without the development of excessive acidity in the cream; 

 and that one of the large problems for the creamerAnian is proper 

 temperature control in both starter and cream-ripening, so as to 

 enable flavor production to keep pace with lactic acid produc- 

 tion. It would seem to be cjuite a safe practice to ripen the 

 cream at a temperature of 70° F., provided care is taken to cool 



