NUTRITIVE VALUE OF POTATOES 11 



The above findings show that, whereas in the raw potato the ascorbic acid is 

 evenly distributed, during the cooking process something happens to change 

 this distribution. Possibly the outer part of the potato, which is in direct contact 

 with the heating medium, maintains a higher temperature throughout the cook- 

 ing process than the inner portion. This probably results in a greater destruction 

 of the ascorbic acid in the epidermal portions and greater retention in the center. 

 Also, in the case of boiled potatoes some ascorbic acid is lost through the leaching 

 action of the cooking water. 



Relation of Size of Tuber to its Ascorbic Acid Content 



Both large and small mature raw tubers of the Green Mountain variety grown 

 on experiment station plots were carefully examined for ascorbic acid content. 

 Marked variations existed in both small and large tubers, but there was no cor- 

 relation between the ascorbic acid content and the size of the tubers. 



The Effect of Cooking on the Ascorbic Acid Content of Potatoes 



Baking and Boiling 



Baked potatoes have long been considered preferable to boiled potatoes because 

 of their better retention of water-soluble minerals and vitamins. As ascorbic 

 acid is water soluble it seemed as though baking would be the ideal method of 

 cooking to retain the maximum antiscorbutic value of the tuber. In order to in- 

 vestigate this point eight varieties of potatoes were both baked and boiled in 

 the customary manner. The boiled potatoes were cooked whole in the skin in 

 water containing 1 percent salt. From Table 8 it may be seen that, contrary 

 to expectations, there was in general less loss of vitamin C in boiled potatoes 

 than in baked potatoes. Baked potatoes showed an average loss of 49 percent 



Table 8. — Effect of Variety and Cooking Methods on the Vitamin C 

 Content of Potatoes 

 (Eight tubers tested for each value) 



Ascorbic .A.cid — mg. per gm. Loss — percent 



Boiled Boiled 



Variety Raw Baked Whole Baked Whole 



in Skin* in Skin* 



Katahdin 0.110 0.108 0.080 2 27 



Chippewa 0.181 0.096 0.086 45 53 



Houma 0.250 0.085 0.165 66 34 



Irish Cobbler 0.157 0.064 0.083 59 47 



Golden 0.131 0.061 0.061 53 53 



Warba 0.146 0.071 0.101 51 31 



Green Mountain 0.132 0.069 0.113 48 14 



Russet 0.161 0.094 0.102 42 37 



Average 0.158 0.081 0.099 49 37 



♦Boiled in water containing 1 percent salt. 



