CEREAL GRAINS 63 



or reniform grains, which vary from 0.025 to 0.050 mm. in length 

 and have a distinct, branching, elongated cleft in the middle. Pea 

 starch grains resemble those of bean starch, but the grains are smaller 

 and more or less irregular on the surface. Queensland arrowroot 

 is obtained from Canna edulis. 



6. Consisting of 2- to 3-compound grains: Cassava or tapioca 

 starch is obtained from the Sweet and Bitter Cassava, and occurs in 

 somewhat plano-convex or bell-shaped, 2- to 3-, or even 4- to 8-com- 

 pound grains, which vary from 0.006 to 0.030 mm. in diameter an 

 have a distinct central, circular, or radiating cleft. Sweet potato 

 starch resembles Cassava starch, but some of the grains are larger. 



Dextrin. Sticky mass with water, consisting chiefly of altered 

 starch grains, but usually sufficient unaltered grains are present to 

 determine the source of the dextrin (Fig. 20, B, H). 



It is chiefly made from either potato or corn starch and depending 

 upon the nature of the process two kinds are manufactured. When 

 heat alone is used yellow dextrin is formed, and when the hydrolysis 

 is assisted by the use of acids, white dextrin or so-called soluble 

 starch results. Dextrin is almost completely soluble in hot water 

 and should not contain more than 5 per cent of dextrose, 10 per cent of 

 moisture and 0.5 per cent of ash. 



Sago starch is obtained from Cycas revoluta and other cycads as 

 well as a number of palms. It occurs in commerce in small, horny 

 granules, which are slowly affected by cold water, when there sepa- 

 rates the characteristic ellipsoidal or truncate-ellipsoidal starch 

 grains. The latter vary from 0.015 to 0.050 mm. long and have a 

 large central area surrounded by rather narrow distinct, altered 

 lamellae. 



Sago (imitation). Usually made, from corn starch and breaks 

 down quickly in water, showing characteristic corn-starch grains. 



MALTUM. Malt. The partially germinated and dried grains 

 of Hordeum sativum, particularly of the variety vulgare (Fam. 

 Graminese). In the preparation of malt the barley grains are soaked 

 in water for twelve to twenty-four hours, placed in heaps, allowed 

 to germinate, being occasionally stirred so that the heat generated 

 on germination does not become excessive. After the protrusion 

 of the caulicle and radicle the material is quickly dried and deprived 

 of these parts. 



Barley. Narrow-ellipsoidal, somewhat 4-angled, 8 to 10 mm. long, 

 2 to 3 mm. in diameter, having an outer, readily separable coat 

 consisting of the inner and outer pales, which are membranous, chaff- 

 like, pale straw-color and somewhat translucent; within the pales 



