MILK AND ITS PRODUCTS. | 
Milk Sugar. —The sugar present in milk is known as lactose. It has 
poor sweetening power compared with cane sugar. The-extraction of it 
from skim mils butter-milk, &c., requires some considerable capital 
to be invested in plant, and unless there is a large available supply of 
raw material, and 1a more extended market, it will hardly pay to extract 
it. It is considered that it costs 6d. a lb. to prepare. The demand has 
been unusual during the war, as much of it was required for making 
smoke shells. Britain requires 500 tons per annum. There appears 
to be a little market for the substance, small quantities being used in 
medicine. Stocks now held are probably sufficient for the supply of 
the world’s demand. It is better economy to divert the sugar to some 
other purpose, such as’ hog food. It is sometimes used in brewing, as 
it is not fermented by ordinary yeast, and so remains in the finished 
product as unchanged carbohydrate, thereby. increasing. the “extract” 
of the beer. 
Lactic Acid.—Lactic acid can be prepared by the fermentation of 
the milk sugar or lactose. As lactic acid exists in several varieties, 
the form that will be produced will depend on the nature of the bacteria 
employed. Pure cultures of “starter” bacteria will generally produce 
the dextro-rotating variety. After the removal of butter-fat and 
caseinogen, the whey is allowed to ferment at 70° to 80° F. The 
liquor is then evaporated to one-third of its bulk, decanted or filtered, 
and saturated with milk of lime. This converts the lactic acid te 
calcium lactate, which remains in solution, while calcium phosphate is 
deposited. This is filtered, and calcium is precipitated with oxalic 
acid, forming calcium oxalate, setting free lactic acid. By a third 
filtration, a solution of lactic acid is left, which is concentrated to 
syrupy consistency and treated with alcohol, which dissolves lactic acid - 
and precipitates lactose and salts. Filter and distil off the alcohol, 
leaving the lactic acid. Of the salts of lactie acid, the antimony 
lactate is used to an increasing extent as a substitute for tartar emetic 
in dyeing and calico printing, and other salts are used in dyeing leather 
and wool. ‘The acid is largely used in tanning for removing the lime 
from the skin. 
AVERAGE COMPOSITION OF MILK PRODUCTS. 
| 
; “* Cream. Butter— 
salted, 
2 eS eee oe aited, : 
Fresh |Separated and Butter prectes f NRE Ye 
= Milk. Milk. Ww astisa, Milk. Cheddar: ro at, NGA 
Thin. Thick. | Ripened : 
Cream, 
Water | 87-2 | 90°5 | 64:0 | 39:4 | 1386] 91°6 37:3 93-0 
Fat .. 377 3 29°3 56°1 83°0 ; 5 33°4 "3 
Protein| 3°6 3-1 2°8 16 8 p33 23°4 “9 
Sugar 4°8 4:8 3:5 2°3 “4 3:4 “4 4°8 
ANSE Hf Wi 3) “4 2-0 “6 a Far “6 
‘Lactic Lactic Lactic 
Acid *6 | Acid 2-0} Acid °3 
223 
