NUTRITIVE VALUE OF CEREAL PREPARATIONS. 225 
containing a third as much more protein than the wheat prod- 
ucts, and nearly twice as much as the corn or rice products. 
As sources of fat also the oat products outrank the others. In 
fact the quantity of fat in the preparations from the other 
grains is in general too small to be of much consideration. In 
the case of the wheat preparations the lack of fat is due to the 
fact that most varieties of wheat contain but a small proportion 
of fat. In the case of the prepared corn products the absence 
of fat is noticeable, because corn contains usually about 4 to 5 
per cent. of fat. In the composition of unbolted corn meal 
given in Table 91, there is 4.7 per cent. of fat. This is present 
mostly in the germ, which is usually removed in the produc- 
tion of ordinary bolted corn meal, because of the tendency of 
the oil to become rancid and spoil the meal. Apparently the 
germ is largely removed in the manufacture of many of the 
prepared corn products, though a few analyses of cooked corn 
preparations have shown from 2 to 3 per cent. of fat present. 
Inasmuch as the functions of food are to build tissue and to 
yield energy, comparison between different foods is sometimes 
based on their protein content and their energy value. In 
respect to the quantities of nutrients and energy actually con- 
tained, the four most important grains would stand in this 
order: oats, wheat, corn, and rice, the two latter being about 
equal. It should be kept in mind, however, that the final 
judgment as to actual nutritive value is based upon the pro- 
portions of protein and energy actually digested and made 
available to the body. ‘The digestibility of the cereal products 
is considered later. 

Crude fiber.— Everyone is familiar with the tough woody 
fiber of vegetables. In chemical analyses such material is 
designated as crude fiber. The outer coat of grains, which is 
protective, contains a considerable proportion of this material. 
Crude fiber is almost entirely undigested by man. For this 
reason, with some of the preparations, attempts are made to 
remove the extreme outer coat of the grain during the process 
of manufacture, and for some brands the claim is made that all 
such material has been removed. The extent to which this 
4s true may be estimated from the figures for crude fiber in 
Tables go and 91. For instance, in shredded wheat preparations 

