1 62 THE CEREALS IN AMERICA. 



235. Protein. — In the analyses of the 208 air-dry samples 

 including all varieties, the protein (N x 6.25) was found to vary 

 from seven to 15.3 per cent. The usual limit of variation lies 

 between eight and twelve per cent.^ 



Osborne ^ has studied the proteids of the maize grain and has 

 distinguished them according to their solubilities as follows r 



" a Proteid, soluble in pure \vater, having some of the properties of proteose. 

 ' b Globulins, insoluble in pure water, but soluble in salt solutions, 



" c Proteid, insoluble in \\^ter and salt solutions, but soluble in alcohol of 60 to 

 99 per cent. 



" d Proteid matter, insoluble in water, salt solutions and alcohol, but soluble in 

 dilute alkalies and acids." 



The most important of these compounds, both on account of 

 its quantity and because it is a characteristic of the maize grain, 

 is the proteid soluble in dilute alcohol, called zein. 



No proteids are found ':?. the maize grain which give to its 

 meal the properties which gluten (mixture of gliadin and glu- 

 tenin) gives to wheat flour. Zein in maize corresponds in some 

 of its chemical properties to gliadin in wheat, but it is neither 

 sticky nor plastic. 



236. Carbohydrates. — The chief constituent of the carbo- 

 hydrates of the maize grain is starch, which may constitute 

 sixty-five per cent of the total dry substance. In the manufac- 

 ture of starch, fifty-five per cent of commercial starch may be 

 obtained from the water-free grain. Besides the starch, the 

 carbohydrates consist of two per cent of fiber, five per cent of 

 gum (pentosans), and small quantities of sugar (sucrose and 

 dextrine). 



237. Fat. — The fat of maize is fluid at ordinary temperatures, 

 solidifying at — 36° F., and is hence known in commerce as 

 corn oil. It is composed principally of linolin and olein and 

 has a specific gravity of about .925.^ 



1 U. S. Dept. of Agr., Yearbook 1901, p. 304. 



2 Conn. Rpt. 1896, p. 391. 



3 111. Bui. 53 (1S98), p. 170. 



