Potatoes in the Dietary 



1545 



five times as much phosphorus as in the flour or the bread purchased; 

 from two to four times as much iron as in the flour, and about ten times 

 as much as in the bread. From the standpoint of acid-forming and base- 

 forming materials, the excess of base-forming elements in ten cents' worth 

 of potatoes may be i6i to 258 units; while in flour there may be an excess 

 of yt; units and in bread of 48 units of acid-forming elements. The ac- 

 comjianying table shows these facts clearly and in condensed form: 



What Ten Cents Will Buy in Grams 



METHODS OF COOKING POTATOES 



effects of COOKING 



Cooking a potato increases its palatability and makes it more easily 

 digested. Heat transforms the water into steam, and the resulting ex- 

 pansion breaks down the cell walls and lets out the starch grains; the 

 protein becomes coagulated, just as the white of egg does when cooked; 

 the mineral salts are only slightly affected. However, by the methods 

 of preparation that are perhaps most commonly used, a very large pro- 

 portion of the nutritious substances may be lost. From all points of 

 \aew, baking and steaming are apparently the best methods of cooking 

 potatoes, and the latter method has the advantage in economy of fuel 

 used. A potato baked in a slow oven is much inferior to a potato properly 

 boiled, however, because the heat has not been intense enough to cause 

 the cell walls to be broken down and the result is a soggy mass on which 

 the digestive juices cannot act freely. Too rapid boiling is likely to pul- 

 verize the outside of the potato before the inside becomes tender, thus 

 causing waste and an unattractive appearance when served. The method 

 by which potatoes are cooked deserves consideration because it affects 

 both the nutrition and the pocketbook. 



losses in cooking 

 The chief ways in which losses of nutritive matter occur in cooking 

 potatoes are (i) in paring, both by cutting away valuable material and by 

 exposing the soluble substances to the action of the water, (2) in exposing 



