2 BULLETIN 717, U. S. DEPARTMENT OF AGRICULTURE. 



The many studies which have been made to determine the actual 

 importance for dietary purposes of the proteins supphed by meats, 

 eggs, and milk show quite conclusively that these proteins are of 

 high biologic value. Unfortunately the supply of these food mate- 

 rials is becoming constantly less adequate to meet the needs of the 

 very rapidly increasing population of this country. Furthermore, 

 these foods are relatively expensive, and consequently can not be 

 eaten as freely as formerly by those of small incomes. As a result of 

 these conditions, students of nutrition have given considerable 

 attention to the possibility of replacing animal proteins with vege- 

 table proteins, and as a consequence the demand for vegetable foods 

 which supply proteins that are of value for human food is steadily 

 increasing. The cereals which contain relatively small amounts of 

 protein are already so extensively used that as a group they now 

 supply nearly one-half of the total protein of the average American 

 diet. While practically all of the common vegetable foods contain 

 protein, the amount present in foods of vegetable origin is small except 

 in the case of the legumes, which may be classed as protein-rich food. 

 Accordingly it appears that a more extensive use of legumes as a 

 source of protein is to be desired. Those legumes most commonly used 

 in this country are the well-known navy beans, red kidney, and lima 

 beans, the garden pea, frijoles, pinto beans, and several varieties of 

 cowpeas. Many studies have been made of the nutritive value and 

 possible uses of these legumes, and several investigators have con- 

 ducted experiments to determine their digestibility. 



INVESTIGATIONS OF DIGESTIBILITY OF COMMON LEGUMES. 



The digestibility of huUed peas cooked thoroughly until soft and 

 passed through a sieve was determined by Rubner,^ who found that 

 the protein was 72 per cent digested. In a second experiment in 

 which the subject ate 600 grams of peas per day the digestibility was 

 found to be 83 per cent. 



MaKatti ^ determined the digestibihty of the protein supplied by a 

 porridge made of split peas and found it to be 86 per cent digested. 



Richtcr ^ reported that in an experiment in which the subject con- 

 sumed 600 grams of puree of pea the protein was 90 per cent 

 digested. 



Snyder ^ conducted three experiments to determme the digesti- 

 bility of pea protein and served a porridge (containing 82 per cent 

 of water) made from dried peas. The porridge was eaten m conjunc- 

 tion with a basal ration consisting of rice, milk, and sugar; one- 

 third of the protein of the diet was supphed by the peas. He found 

 that the average digestibility of the pea protein was 80 per cent. 



I Ztschr. Biol.' 16 (18S0), No. 1, pp. 119-128. s Arch. Hyg., 46 (1903), No. 3, pp. 264-273. 



> Jahresber, Tiw-Chem., i5 (1885), p, 412. * Minnesota Sta. BuJ. 92 (1905), pp. 267-270. 



