NUTRITIVE VALUE OF POTATOES 3 



the diet. In Table 1 it is shown that potatoes contain approximately 1 percent 

 of ash or minerals. This important 1 percent may be further broken down and 

 analyzed as presented in Table 2. 



Table 1. — Aver.a.ge Chemical Composition of Edible .Portion of the 



Potato* (7) 



Water 77 . 80 percent 



Protein 2 . 00 percent ■ 



Fat 0.10 percent 



Ash (minerals) . 99 percent ' ' 



Carbohydrate (starch, sugars, etc.) 19. 10 percent 



Fuel or energy value 385 calories per pound or 



85 calories per 100 grams 

 Approximate potential reserve alkalinity 9.0cc. normal alkali per 100 grams 



♦Additional data on the composition of potatoes and other vegetables may be found in a recent 

 bulletin by Holland and Ritchie (20). 



Table 2. — The Mineral Content of the Edible Portion of the Potato 



Mineral Percent Authority 



Calcium 0.013 41 



Magnesium 0.027 41 



Potassium 0.496 41 



Sodium 0.024 41 



Phosphorus 0.053 41 



Chlorine 0.035 41 



Sulfur 0.029 41 



Iron 0.0011 41 



Copper 0.000164 41 



Manganese 0.000173 41 



Nickel trace 4 



Cobalt trace 4 



Barium trace 34 



Zinc 0.0004 3 



Iodine 85-226 p.p.b. of 14, 18, 33 



dry matter 



Aluminum 0.00097 50 



FACTORS INFUENCING THE COMPOSITION OF POTATOES 



Fertilization, Soil, and Variety 



The composition of plant material is subject to variation according to variety, 

 soil, and fertilization. Potatoes are no different from other plant materials in 

 this respect. Considerable work has been published dealing with the composition 

 of potatoes as influenced by variety, soil, and growing conditions. Metzger and 

 co-workers (35) have summarized a 'comprehensive study on the composition of 

 potatoes as follows: 



