Evening star., 1954-01-18
Glass Stomach Aids
Study Of Proteins
Scientists Leurn Effects
Of Cooking on Foods
By Thomos R. Henry

A glass stomach has been developed
by Department Of Agriculture scientists.
It Stimulates the digestion process in
rats stomach--and essentially that
In human stomach also-to measure
the value Of various foods in building
up proteins, which constitute about q
NTH Of the body.
These proteins are extremely COM
plex chemical structures built up Of
approximately 20 simpler materials.
the so-called amino acids. Most ami
mails can synthesize about half of these
In their own bodies. The other half
must be supplied in the food, and the
ones required differ for different
animals.
Chemical analysis Is extremely diff
cult and time consuming. It Is doubt.
full. according to a Department Of
Agriculture announcement, whether
any food has been completely analyzed
for its amino acid content. Some
years ago. however, q simpler method
was devised. Bacteria need all the
acids. So the food being tested was
broken down chemically with strong
hydrochloric acids and placed in q
mixture containing all but one Of the
vital substances. The rate at which
the bacteria grew was q measure Of
the amount Of the one acid missing in
the mixture which was supplied by
the food.
Bacteria Mixtures Inadequate.
It soon became apparent, however,
that this measure was impractical
simply because rats and men are not
bacteria. Mixtures on which the micro
organisms thrived proved inadequate
for the higher forms of life. This, it
was believed, was due to the fact that
the process Of digestion, breaking up
food into its constituent elements, does
not involve strong hydrochloric acid
treatment to break down chemical
bonds. This is done by much milder
process, in which hydrochloric acid
plays part but which also involves
numerous other materials. These are
known. rs.
They are placed, together with the
food being tested, in the new glass
stomach. There the food is being
broken down just as it would be in an
animals stomach. It is then fed to
the bacteria and their growth rate
measured. Quite different results are
found from those obtained with the old
method. Great variations, the glass
stomach shows, are caused by heating
and cooking which in many cases tight
ems the chemical bonds holding the
amino acids so that normal digestive
processes cannot release them.
Tests of Influence of Heat.
Research now under way, according
to the Department announcement, is
showing for the first time what ordi-
nary cooking does to common foods.
Some 40 foods. raw and cooked, have
been checked so fal by the glass stomach
technique to show how much of each
essential amino acid they contain, and
how much is available to the bacteria.
Animal proteins, such as those in
meat. milk and eggs, are not damaged
by cooking and some may be improved.
it has been found. Vegetable proteins,
however. may be greatly damaged, so
far as their nutritive value is con-
cerned. Severe heat seems to tie I'D
half or more Of the amino acids in
such foods as wheat, peas and beans.
This indicates. according to the Bu-
reau of Home Economics scientists, M.
j. Horn, A. E. Blum and Madelyn
Womack. that the whole field of cook
ing should be re-examined. They see
some possibility of great advances in
the new electronic cooking, which does
not require heat.
Meanwhile, they stress, housewives
will do well to hold down cooking times
and temperatures as much as possible.
Eventually new food composition tables
will show the available protein content
and complete amino acid distribution
in various foods. 1t then will be pos
sible to plan nutritious meals using
low-cost proteins, such as those found
in plants. that complement each other
In terms of amino acids.