


NUTRITIVE VALUE OF CEREAL PREPARATIONS. 22:9 
Carbonates are also-mineral salts, and although they may be 
present in very small quantities in food, it is not these but the 
carbohydrates and fats that are the heat producers. A familiar 
example of the carbonates is the bicarbonate of soda used in 
baking. 
It is needless to continue such discussion. Enough has been 
stated to show that little account should be taken of the exag- 
gerated statements concerning the nutrive value of cereal prep- 
arations. The most that can be said for these products is that 
in actual composition they very much resemble other food prod- 
ucts from the same grains. But this is quite sufficient. 
DIGESTIBILITY OF CHREAIL PREPARATIONS. 
The chemical composition of a food material merely shows 
the kinds and quantities of nutritive ingredients it contains. 
The actual nutritive value of the material, however, depends 
upon the extent to which the different nutrients may be digested 
and absorbed. Most food materials when eaten are in such form 
that they cannot be taken directly into the circulation, but must 
first be converted into substances that are capable of being 
absorbed. ‘This change is brought about in the alimentary 
canal, by the action of certain ferments in the digestive juices 
that are there mixed with the food. Any part of a food sub- 
stance that for any reason is capable of resisting the action of 
the digestive juices cannot be absorbed, and therefore does not 
serve to nourish the body. 
For this reason one very essential part of the study of the 
nutritive value of foods consists in determining what quantities 
of the nutrients of different food materials are digested when 
eaten. Such information is obtained from actual experiments 
with men. Several such digestion experiments with cereal 
breakfast foods made at this station are described in the pre- 
ceding article in this report. Similar experiments have also been 
made elsewhere with other cereal preparations. The number 
of experiments yet completed is hardly large enough for defi- 
nite conclusions regarding all sorts of cereal products; for in- 
stance experiments with corn, rice and barley products are not 
yet reported; but the information already obtained is decidedly 
interesting, as will appear from a consideration of the figures 
summarized in the following table. ‘The figures are here given 
