[Sidenote: Condition of food influences chemical action]
Chemistry is not the only factor in the digestive function that is to be
taken into consideration. The mechanical condition of food, when it is
taken into the digestive organs, very greatly influences the chemical
process that takes place.
[Sidenote: Necessity for thorough mastication]
This involves the question of masticating or subdividing the food into
small particles. The greater the dissolving surface, the more rapidly
will solution take place. If the substance being dissolved is a firm
particle, the digestion or solution will take place only on the exterior
surface, and the interior of the particle, however small, will remain
practically unchanged. This is what occurs when food materials such as
grains and nuts are taken in an uncooked state, as mastication does not
dissolve them, but only divides them into small, distinct particles.
[Sidenote: Action of enzyms during digestion]
If, however, the grain be subjected to prolonged heating with water,
partial solution takes place. The entire mass becomes mushy and
permeated with moisture. When such a mass is brought in contact with
the digestive fluids, it mixes or disintegrates with the fluid, just
as molasses would mix with water. The result is that the whole mass of
material is subjected to the action of the digestive fluids at once,
with the result that the mass is passed from the stomach too quickly,
causing congestion in the small intestines, or the whole is arrested,
and fermentation and decomposition take place. In normal digestion,
the enzyms are continuously secreted for a period of several hours.
They begin work on the outside of the food particles, dissolving the
substances gradually. Thus the enzyms are continuously used up, and
the digestion proceeds slowly, but naturally, yet as fresh enzyms are
continuously being secreted to act on the newly exposed surfaces, active
and complete digestion is constantly taking place.
[Sidenote: Predigested "breakfast foods"]
The alleged predigestion of certain proprietary foods has neither
scientific basis nor virtue. That the juices of some fruits which are
already in the form of glucose, can be immediately absorbed into the
tissues without any digestive process, does not prove that the mushy
cooking, malting, and other forms of so-called predigestion are
beneficial. The so-called "predigested breakfast foods" are not and
cannot be prepared by any process for final digestion, but are in an
intermediate state between starch and glucose. They are composed of a
semi-soluble starch, gummy dextrin, and perhaps a little maltose which
has a tendency to disturb and to interfere with the normal process of
digestion.
[Sidenote: Comparative digestibility of cooked and uncooked starch]
I do not advocate the use of uncooked grain, but I wish to correct
a popular error in regard to the digestibility of uncooked cereal
starch. Nearly all works on physiology and diet make the statement
without reserve that raw starch is indigestible. This theory has been
established by putting samples of cooked and uncooked starch into two
test tubes, and treating them with some digestive enzym. The cooked
starch, being soluble, is all exposed to the digestive enzyms at one
time, and started on its way through the numerous changes in the
complex chemical process of changing starch into glucose, while in the
sample of uncooked starch, the digestive enzym attacks the particles
from the outside, and slowly digests or eats off the exterior of the
starch grains. After a given length of time the chemist adds iodin to
the two test tubes. With starch, iodin gives a blue color. In the test
tube containing the cooked starch, all of which has undergone a certain
amount of digestion, no blue color is discerned, for no pure starch is
left, while in the other tube, in which some of the particles remain
unchanged, owing to the fact that Nature does all her work slowly, a
blue reaction is of course obtained, and the chemist proclaims that
uncooked starch is indigestible.
[Sidenote: Government experiments with cooked and uncooked grains]
At one of the United States Experiment Stations in the state of Kansas,
a comparison of two diets, consisting chiefly of several varieties of
grains, was recently made. The diets were alike in every respect with
the exception that in one instance all the grains were boiled for two
hours, while in the other case they were taken in an uncooked state.
In the case of the uncooked grains, no starch whatever passed through
the body in an undigested form. In the case of the cooked grains, the
same results were found; that is, no starch was found in the intestinal
residue. Other substances, however, remaining undigested in the cooked
diet, were much in excess of that in the uncooked, yet no starch was
present. In the case of cooked grains, the digestive processes may
start with more rapidity than in uncooked grains, yet they are not
thoroughly completed, and various decomposition products occur, as well
as undigested proteid, which is not likely to occur with foods taken in
their natural state.
[Sidenote: Uncooked starch harmless]
Moreover, if uncooked starch be taken in excess of the digestive
capacity, and passed through the body wholly unchanged, no harm results.
The starch grain, in its unchanged state, is a fine, white glistening
granule, and its presence in the digestive tract would have no harmful
effect upon the body functions. Without solution, no material can have
any effect upon the physiological processes, except by irritating the
mucous surfaces of the digestive organs; in the latter respect, starch
granules are harmless.
[Sidenote: Condition in which food should enter digestive organs]
With the exception of articles that are in solution, the condition in
which all foods should enter the digestive organs is in finely divided,
yet distinct particles, and not in pasty or gummy masses. In this latter
form "bolting" is encouraged, and mastication greatly discouraged.