POTATOES AND OTHER STARCHY ROOTS AS FOOD. 



27 



COMPOSITION AND ENERGY VALUE OF TROPICAL STARCHY ROOTS AS COMPARED 

 WITH POTATOES AND SWEET POTATOES. 



Table III shows the composition of the tropical starchy roots as 

 compared with potatoes and sweet potatoes. 



Table III. — Average composition of edible portion of dasheen and other tropical 



starch-bearing roots. 







Water. 



Protein. 



Fat. 



Total carbohy- 

 drates. 



Ash. 



Fuel 



Kind of food. 



Sugar, 



starch, 



etc. 



Crude 

 fiber. 



value per 

 pound. 





Per ct. 

 66.0 

 10.5 

 10.5 

 10.3 

 72.9 

 65.7 

 70.9 

 70.0 

 78.3 

 69.0 



Per ct. 

 1.1 

 .5 

 9.1 

 1.1 

 1.8 

 3.0 

 1.8 

 2.2 

 2.2 

 1.8 



Per ct. 

 0.2 

 .1 

 .3 

 .2 

 .2 

 .2 

 .2 

 .2 

 .1 

 .7 



Per ct. 

 30.2 



Per ct. 

 1.8 



Per ct. 

 0.7 



.1 

 1.1 

 1.6 



.9 

 1.3 

 1.2 



.9 

 1.0 

 1.1 



Calories. 

 610 





88.8 

 79.0 



1,625 





1,610 

 1,605 





85.2 

 23.3 

 28.8 

 23.2 

 26.1 

 18.0 

 26.1 



1.6 

 .6 

 .7 

 .8 

 .6 

 .4 



1.3 





475 





605 



Taro 



475 





530 





380 





560 









/,000 &1£jO#/£S 



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SSO G4££2#/£S 



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The preceding diagram (fig. 6) shows in graphic form the com- 

 position of sweet potatoes, Irish potatoes, 

 and other starchy roots, and perhaps 

 makes clearer data such as are recorded 

 in the table. 



It is apparent from the diagram that 

 these typical starchy roots are very simi- 

 lar in general composition. Degree of 

 ripeness, length of storage, and other fac- 

 tors influence water content considerably. 

 Individual specimens of any one of them 

 would vary more or less in water content, 

 but on the average water makes up about 

 two-thirds to three-fourths of the total, 

 while carbohydrates constitute the greater 

 part of the nutritive material. These 

 vary in the different groups, starch being 

 the characteristic carbohydrate of pota- 

 toes, cassava, and dasheen; sugar and 

 starch of sweet potatoes; and inulin, lev- 

 ulin, and pectose bodies of Jerusalem 

 artichokes. The proportion of protein in 

 these roots is small, but valuable in nutri- 

 tion, in part because of the vitamins 

 believed to accompany the nitrogenous 

 material. The proportion of ash is actually small, though relatively 

 large as compared with other foods. As a group, starchy roots are a 



I I 



S60 G4LO/?/£S SOS C4t.O/?/£S 



I 



Fig. 7. — Energy value of some 

 common starchy vegetables. 



