114 THE BOOK OF BUTTER 



lation will ripen a starter in twelve hours at about 65 F. 

 The temperature must be fairly constant. 



8. The starter is ripe when a curd forms. This curd 

 should be soft and custard-like in appearance; it should 

 not be hard and firm. In the soft custard-like condition 

 the acidity is approximately .7 per cent lactic acid. 

 When firm and hard the acidity may be as high as .95 

 per cent lactic acid. Usually it does not exceed .9 per 

 cent acidity. When the acidity is high, the lactic acid 

 bacteria themselves die and other micro-organisms grow 

 which produce various flavors, especially the disagree- 

 able putrefactive flavor. This is the worst stage of over- 

 ripening, and it should be avoided. 



9. When the starter is ripe, it should be used at once. 

 If this is impossible, cool to 50 F. or lower. If the con- 

 tainer is small, do not shake the starter before putting it 

 in storage. Sometimes it is desirable to cool a large batch 

 of starter fairly quickly so that it will not over-ripen. 

 In such case, it may be agitated if it is immediately cooled 

 to 50 F. or below. 



10. On examination, the curd should be smooth, com- 

 pact, and without gas pockets. Gas shows the presence 

 of undesirable bacteria. A hard and lumpy curd, whey, 

 and high acid show over-ripeness. These are very undesir- 

 able. After the state of the curd is noted, shake well to 

 break it into a smooth lumpless condition. Shake with 

 a rotary motion, being careful not to permit the milk to 

 come in contact with the cap for fear of contamination. 

 Now smell and taste it, but never from the starter con- 

 tainer. Always pour some of the curd into a spoon or 

 cup and then replace the cover immediately. After smell- 

 ing, it is best to put at least a teaspoonful into the mouth. 

 When starter is lumpy it does not taste the same as when 



