398 MILK 



BUTTERMILK 



Buttermilk is the chief representative of the first class of 

 fermented milks. Originally buttermilk means the sour skimmed 

 milk left in the churn after butter has been removed. Usually 

 cream is allowed to sour and is churned when the acidity has 

 reached about 0.6 per cent. The buttermilk contains a higher 

 percentage of acid than the cream from which it is made, since 

 its volume is reduced by the removal of the fat, while the actual 

 amount of acid remains practically the same and is present, there- 

 fore, in greater concentration in the buttermilk than in the sour 

 cream-. It is not uncommon to dilute the sour cream before churn- 

 ing, as this facilitates the separation of fat. The buttermilk, 

 therefore, does not contain the same percentage of plasma solids 

 as the cream. The amount of fat in buttermilk from the churn 

 is about 1 per cent. 



Commercial buttermilk is now largely made from skimmed 

 milk after inoculation with a starter, and is sometimes called 

 "ripened milk." Since the introduction of the cream separator 

 a highly concentrated cream can be obtained and the quantity 

 of buttermilk is relatively small. The skimmed milk as it leaves 

 the separator contains about 0.1 per cent, fat or less, and is in- 

 oculated with a starter consisting of a culture of Streptococcus 

 lacticus. After loppering, the milk is churned and sold as butter- 

 milk. 



Buttermilk is churned sour milk from which the greater part 

 of the fat has been removed. The churn buttermilk is richer 

 in fat than the artificial product, but the latter contains the full 

 amount of protein, milk-sugar, and mineral matter because un- 

 diluted, and is, therefore, a more nutritious product than butter- 

 milk made from diluted cream. The amount of acid in commer- 

 cial buttermilk is from 0.7 to 0.9 per cent. In freshly churned 

 buttermilk the casein is evenly suspended, but as it stands the 

 coagulated flakes gradually settle and the palatability of the but- 

 termilk suffers. 



The composition of buttermilk made from sour cream, sweet 

 cream, milk, and separated milk is given on page 74. 



A good substitute for commercial buttermilk can be made by 

 allowing sweet milk to lopper and then beating it until smooth. 

 If whole milk is used the aroma of the product is superior to that 

 of commercial buttermilk because the fat is not removed. After 

 pasteurization milk does not sour as readily as raw milk, and for 

 making buttermilk pasteurized milk should be inoculated with a 

 commercial starter or with a small amount of a previous lot. It is 

 always advisable to use pasteurized milk for preparing butter- 



