characteristics. The best are soft, white fleshed, and often delicious. D. 

 nummularia seems to be the best of the minor yams for its taste, but the 

 poorest in keeping quality. 



COMPOSITION 



Although occasional reports on the composition of the minor yams 

 are found in the literature, it is difficult to accept these without some 

 reservations because they are usually based on the analysis of a single 

 specimen. No collections have been assembled which would permit an 

 adequate evaluation of a species. Some analyses given by Brown {3) are 

 given below: 



[Per 100 graym fresh cut} 









Crude 











Calories 





Water 



Ash 



fiber 



Protein 



Fat 



Starch 



Sugar 



per 





(g) 



(g) 



(g) 



(g) 



(g) 



(g) 



(g) 



kilogram 



D. penta- 



















phylla 



74-75 



0.6-1.1 



0.5-0.6 



0.7-2.4 



0.2-1.6 



17.3-19.2 



0.4-1.1 



800-1,000 



D. alata 



64-72 



.8-1.4 



.7-1.4 



1.4-3.5 



0-0.3 



17.1-27.6 



.6-0.9 



880-1,200 



Similar data are given by Bourret (1) for three of the species 

 (table 2). 



The chief substance in the tuber other than water is starch. The 

 starch of D. dumetorum is fine and difficult to precipitate, with a high 

 gelling temperature and a low viscosity {18), Amylose content is only 

 about 14 percent, a little more than half that of most other yams. The 

 starch of D. hispida is also fine but rapidly settles from solution. The 

 starch grains of D. nummularia are large, and the amylose content is 

 higher (about 26 percent). The starch grains of D. pentaphylla are large, 

 up to 110 micrometers in length, with an average of 30 to 40 microme- 

 ters. The starches of D. dumetorum and D. hispida might be useful 

 for industrial purposes when small grain size and low amylose content 

 are desired. Schemes for the production of D. hispida starch were pre- 

 sented by Rao and Beri (17). 



Table 2. — Chemical composition of three minor species o/Dioscorea 

 compared uoith D. alata^ 

 [Percentage fresh matter] 



Species 



Water 



Ash 



Cellulose 



Fats 



Protein 



Starch 



D. alata 



( 59.8 



0.6 



0.2 



0.1 



1.6 



37 





' 58.2 



1.1 



.4 



.2 



2.2 



37 



D. nummularia . . . . 



( 75.3 



.8 



.4 



.1 



1.8 



21 





^ 68.9 



.8 



.7 



.2 



1.6 



28 



D. pentaphylla 



86.3 



.5 



1.3 



.1 



.9 



11 



D. transversa 



67.8 



.9 



.5 



.11 



1.8 



29 



^See referenced. 



21 



