The Democratic advocate. [volume] (Westminster, Md.) 1865-1972, 1883-04-14
Our Olio.
A Grain of Starch.
From Chambers Journal.

mere may NOT seem mucn In grain OF
starch, and in point of bulk there is very
little; but we shall endeavor to show that
there is good deal of interesting and val
liable information to be derived from
careful study of the little granule.
We are all familiar with such commodi-
ties as -four, potatoes, Indian corn, sago,
peas and arlowroot, and are consequently
to some extent acquainted with what starch
is; for all these substances consist essen
TALLY of starch, along with water and some
minor admixtures IF we take slice of
potato, for instance, and rub it on a
crater of any sort in basin of cold water,
the water will soon become turbid; and
drop of it examined with microscope will
be found to contain number of minute
oval granules, which would in time sink to
the bottom of the basin, forming white
deposit. These are grains of starch; and
so minute are some varieties that three
thousand of them laid end to end would
barely make an inch
The starch of every plant differs from
its neighbors both in size and shape, and
this has considerable influence ON the
character of the vegetable organ in which
it is stored up; the hardness of rice, for
instance, being due to the fact that rice
granules are extremely minute, with angu-
lar corners which fit closely and firmly to-
gether; whereas potato starch is large and
round, with considerable interspaces filled
with water, and so forms comparatively
soft mass. But, Notwithstanding their out
ward points of difference, in chemical COM
position the starches are all identical, con-
sisting Of carbon, hydrogen and oxygen
exactly the same materials as sugar is COM
posed of, and better known as the cOmpo-
nent elements of coal and water. Leaving
the many varieties of starch in the mean
while, let us consider one species, namely,
that of wheat, because it is the most I'M
portant in this country, forming the basis
of our daily bread.
An ordinary grain of wheat if sliced
through the middle and examined as to its
structure, will be found to consist of several
layers, the outer hard coating, which con-
tains mineral salts, lime, sand, etc. Be-
meath this is zone of matter very rich in
gluten, the fesh-forming constituent Of
wheat; while the central portion of the
grain is occupied by white, powdery mass,
which is nearly pure starch. In manufac-
turing -four, the two outer layers, which
together form the bran, are usually remOv
ed, leaving the white starchy -four of the
central portion.
Let us now briefly consider the chief
points in the chemistry of bread-making.
If -four be worked up with water, it forms
a sodden, insipid, indigestible mass; but if
heated to the temperature of boiling water,
the starch granules burst; and it is thereby
rendered a little more digestible, although
still forming close, stiff and not very pal
atable cake Such is the character of un-
leavened bread and of sea-biscuits, a
slightly different form of the same thing.
To be fit for digestion, starch must be dis
solved or softened by boiling or baking;
hence the reason W by raw nuts are SO in
digestible as compared with the favorite
roasted chestnuts; and hence one reason for
cooking food, which mankind has been
taught by experience, ages before chemis-
try could give a scientific explanation of
the reason why Cooking is, in fact,
partial digestion; and the same is the case
with baking, both being preliminary aids
to the changes which take place in the
mouth and stomach before the food is in a
fit state for the preparation of the blood
Accordingly, we bake our bread, and we
bake it in the way we do because soft,
spongy loaf is more readily moistened and
acted on by the saliva and the juices of the
stomach.
There is a good deal in the chemistry Of
bread-making, and our bread might be
much improved if bakers had more intel
ligent understanding of the science involved
in their business; for, although several i'm
provements have been introduced of late
wears, the most of our bread is still pre-
pared in the old fashion. The necessary
quantity of -four is put into trough with
about half its weig ght of water, and sufi-
cient salt and yeast or leven; then thor
oughly mixed up into what is known as
the sponge Here We may remark that
the best flour takes up the largest quantity
of water; and a rough test of the quality
of two samples of -four may be made by
comparing the quantity of water required
to obtain a dough of similar consistency
After the sponge is made, it is left for
about five hours in a warm place to fer
ment, after which it is kneaded with the
rest of the -four, and again left to rest some
time. The dough is then weighed into
humps, which are put in tins, and set aside
till they have risen to twice their previous
bulk. 1t is to the yeast or leaven that the
rising of bread is due, and the action is
identical with that of the fermentation of
beer. The -four contains small amount
of nitrogenous substance which changes
portion of the starch into sugar; the yeast
then attacks the sugar, splitting it into al
cohol and carbonic acid gas, the little bub-
bIes of which try to escape from the mass
of the dough, but get entangled by the
gluten and gum which the -four contains;
and thus every part of the bread becomes
penetrated with little cavities. Eventually
the fermentation would cease, and the bub-
bles of gas would find their way to the out
side, thus leaving the dough much less
light and spongy than we wish it to be;
but the baker guards against this by put
ting it at the proper time into hot oven,
tie heat of which at first increases the fer
mentation In a few minutes, however,
the temperature becomes sufficiently high
to kill all the yeast germs; the fermentation
is thereby stopped, and by continued heat
ing the starch granules are burst, and the
mass is fixed in the porous form it has then
attained. A little of the alcohol is retained
in the bread; but practically almost the
whole of it-in London amounting to some
three hundred thousand gallons per annum
is driven off by heat. During the bak-
ing the starch of the outer portions of the
bread has been Drowned by the heat, and
thereby changes into a sugar known as
dextrin or British gum; and perhaps this
fact accounts for the fondness of some chill
dren and even grown-up people for crusts.
La Iii hot