POTATOES AND OTHER STARCHY ROOTS AS FOOD. 



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partment 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 

 water is hard or soft. Soaking the potatoes in water before boiling 

 greatly 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. X)n 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 way 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 

 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 



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. 



In some families it is a common 



