266 



ASCORBIC ACID 



lability of the vegetables has been passed, and extended cooking should 

 therefore be avoided. Similarly, a relatively higher loss is to be anticipated 

 as the ratio of water to vegetable is increased. From the dietetic point of 

 view, this leaching is of little significance with stewed fruits, where the 

 juice is eaten with the tissue, but it may represent a serious loss with vege- 

 tables when the cooking water is drained away before serving. 



If vegetables are steamed instead of boiled, the leaching effect is negli- 

 gible but a greater loss of vitamin is to be expected from oxidation. In 

 pressure cooking, owing to the extremely small amount of water used, the 

 amount of ascorbic acid lost by extraction is small but, compared with 



TABLE VII 

 Effect of Household Cooking on Ascorbic Acid Content of Vegetables 



(Typical values) 



" Ratio of water to vegetable high; long cooking time. 

 Ratio of water to vegetable low; short cooking time. 

 Whole or large pieces. 



normal boiling, the destruction is greater. The over-all effect is that identi- 

 cal vegetables cooked under increased pressure and at normal pressure have 

 similar antiscorbutic values, provided that the processing is continued in 

 each case only to the point of maximum palatability of the vegetable. Ex- 

 tended time of cooking will result in correspondingly greater loss of the 

 vitamin when pressure is used than with normal boiling methods. 



Keeping drained vegetables hot for an extended period before serving 

 is to be deprecated from the nutritional standpoint since progressive oxi- 

 dation of the vitamin has been found, especially when the tissue is finely 

 cut or divided as with mashed potatoes or chopped green vegetables. 



In Table VII attempts have been made to summarize the general findings 

 of many workers when different methods of cooking have been in\'estigated. 

 It will be appreciated, however, that, owing to the number of possible 



