BUTTERMILK 237 



25 — 30 per cent, of fat. In the experiments at 

 Geneva, U.S., 91 '0 per cent, of the fat in milk was 

 obtained as butter from Guernsey, 891 from Jersey, 

 836 from Holderness, 82'3 from Devon, 79'1 from 

 Ayrshire, and 74*6 from Holstein cows. 



Composition. — Good fresh butter will usually contain 

 12 — 15 per cent, of water, and salt butter 10 — 16 per 

 cent. Fresh butter will contain 84 — 87 per cent, of 

 butter fat ; the other solid constituents will be about 

 one-tenth of the water if the butter has been un- 

 washed, or less when washing has taken place. Salted 

 butter will usually contain 1 — 2 per cent, of salt, but 

 in very salt butter 4 — 7 per cent, may be present. 



The chemical characteristics of batter fat which 

 distinguish it from animal fats, and thus allow of the 

 detection of adulteration, have been already mentioned 

 (p. 226). When butter becomes rancid, the glycerides 

 of the fatty acids are partly decomposed and the 

 fatty acids liberated. The odour and flavour of 

 rancid butter are largely due to free butyric acid. 



Buttermilk.— The liquid remaining in the churn after 

 the separation of the butter from the cream varies a 

 good deal in composition. The more perfect is the 

 churning the smaller will be the percentage of fat left 

 in the buttermilk. With good churning of ripened 

 cream the percentage of fat in the buttermilk may be 

 0*3, or even less. When sweet cream is churned 1*0 

 per cent, of fat may be expected. The average com- 

 position of buttermilk from ripened cream will be 

 about — water, 90*9; albuminoids, 3*5 ; fat, 0*5 ; sugar 

 and lactic acid, 4'4; ash, 0*7. The albuminoid raliv, 

 would be 1 : 1*5. 



