POTATOES AND OTHER STARCHY ROOTS AS FOOD. 
9 
xpartment of Agriculture and by others to determine just how much 
of the different nutrients is lost when the potatoes are cooked in vari- 
ous ways. It was found that the loss is much the same whether the 
w T ater is hard or soft. Soaking the potatoes in water before boiling 
greatty increases the amount of nutrients extracted. When they 
are put in cold water and brought to a boil they lose twice as much 
of their protein (15.8 per cent) as when they are plunged at once into 
boiling water ; the loss of mineral matter is about 18 per cent of the 
total present by both methods. On account of these losses in boiling 
potatoes many persons consider steaming preferable. 
The tests just noted were all made with pared potatoes, but another 
series was made with unpared ones, in which it was found that when 
boiled in their jackets potatoes lose only 1 per cent of their protein 
and a little over 3 per cent of 
their ash, no matter what the 
temperature of the water is at 
the start. Almost no starch is 
removed when potatoes are boiled 
in their skins, but when pared 
the mechanical action of the boil- 
ing water wears off the outer 
surface, and in this way as much 
as 3 per cent of the carbohy- 
drates may be lost. 
Evidently, then, by far the 
most economical w 7 ay to boil po- 
tatoes is in their jackets. When 
they are cooked this way they 
should, of course, be thoroughly 
scrubbed before cooking and are 
sometimes, particularly in the 
case of new potatoes, scraped to 
remove the greater part of the skin. In some families it is a common 
practice to remove a section of the skin at each end of the potato or to 
pare a ring around the middle of the tuber so that the moisture may 
escape and the cooked potato may not become soggy on standing. 
If they are pared before cooking, they should be placed directly in 
hot water. 
When baked in their skins, potatoes probably undergo much the 
same changes as in boiling, but they lose practically none of their 
ingredients except a little water which evaporates through the skin. 
Some of their moisture changes to steam inside, and unless the pota- 
toes are to be eaten immediately it must be allowed a way of escape 
or it will change back to water and make the potatoes soggy. This 
explains the practice of breaking, cutting, or pricking the skin of the 
baked potatoes when they are taken from the oven. 
61353°— Bull. 468—17 2 
k&roj; 
Fig. 5. — Composition of the potato and 
loss of nutrients when it is boiled with- 
out paring. Shaded portion shows loss 
in boiling of 2.8 per cent of the water 
and 1 per cent of the protein. Unless 
portions break off no starch (car- 
bohydrate) is lost. A little over 3 per 
cent of the ash is lost in boiling. 
