THE FOOD VALUE OF VEGETABLES. 



25 



For example, if on analysis a vegetable is found to contain of 



Proteid i per cent. 



Carbohydrate . . • 5*8 » 

 Fat .... o-4 



Then the energy value of ioo grammes would be : — 



From proteid I X 4*i = 4*1 Calories 



„ carbohydrate 5*8 X 4*i = 2378 „ 

 „ fat 0-4 X 9/3 = 372 „ 



Total Food Value = 31-60 Calories. 



Turning now to the worth of particular vegetables or groups of 

 vegetables, and beginning with the potato, we find that it owes its 

 value principally to the large amount of absorbable carbohydrate 

 it contains, and to a less extent to its proteid. Its vitamine value 

 I have already referred to. 



If a transverse section of a tuber be examined, three distinct 

 layers can be made out. The central one constitutes the largest 

 portion of the total bulk ; this is enclosed by the fibro-vascular layer, 

 somewhat darker in colour, makirg about one-twelfth of the entire 

 tuber. This layer is rich in proteid. The outermost layer forms 

 the skin. 



If a potato is peeled before cooking, a large amount of the middle 

 layer is usually cut away and thus a great deal of proteid is lost. 

 And again in the boiling of a potato, particularly when peeled, a 

 large amount of nutriment is dissolved out by the water. There- 

 fore it follows that, to obtain the maximum of food from it, we must 

 cook it by steam or by baking without removing the outer rind. 

 By this means also the true flavour is preserved. An analysis 

 of the absorbable food of the potato gives : — 



Proteid. Carbohydrate. Fat. 



0-9 19-1 O'l 



and consequently the caloric value is 82-9. 



Legumes. — The most noteworthy feature in the members of this 

 group is their richness in proteid. They contain a proteid called 

 ''legumin " which closely resembles the casein of milk, and in some 

 parts of the country a kind of cheese is made from it. Legumin 

 combines with lime salts to form an insoluble compound, and therefore 

 it is inadvisable to boil peas and beans in hard water without first 

 precipitating the lime with bicarbonate of soda. 



The legumes are also well provided with carbohydrates, but are 

 poor in fats. Although they are not easily digested, they are well 

 absorbed in the intestine and their nutritive value is high. 



The habit of eating young kidney beans with their pods is not 

 only altogether wasteful, but from a health standpoint very injudicious, 



