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Strange Uses of Starch
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The Secret of Everyday Things |
by Jean Henri Fabre |
Fascinating conversations with Uncle Paul reveal the mysteries behind the dyeing and weaving of cloth, the lighting and heating of homes, the processing involved in bringing oil, coffee, tea, spices, and other foodstuffs to the table, and the power of water in all its manifestations. Excellent as follow-on to The Story Book of Science. Ages 11-14 | 387 pages |
$14.95 |
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STRANGE USES OF STARCH
[271]
FTER explaining the important part played by starch in
plant life Uncle Paul took occasion to name some of the
less familiar sources of this substance and to describe
how it is used for purposes very different from that so
well known to every housewife and every laundry-maid.
"All starch," said he, "whether it be derived from one
plant or another, from a seed or from a root, is
readily convertible into sugar either by the natural
processes going on in vegetation or by artificial
processes employed by man. The simplest expedient is
the application of heat, a factor entering into the
preparation of farinaceous foods. Let me illustrate by
a few examples.
"A potato in its raw state is uneatable. Cooked in
boiling water or roasted in the ashes it is excellent.
What then has happened to it? Heat has turned a part of
the starch into sugar, and the tuber has become a mass
of farinaceous dough, slightly sweetened. We can say
about the same of the chestnut. Raw it is not good for
much, though at a pinch it can be eaten; cooked, it
deserves all the praise we give it, and I am sure you
will back me up in this assertion. Here again we have a
transformation of starch to sugar by the action of
heat. Beans and peas, hard as bullets when dry, and far
from
pleas- [272] ing to the palate, are unmistakably sweetened as soon
as boiling water has worked upon their starch. Our
farinaceous foods of sundry sorts behave in similar
manner."
"Then do we make sugar," asked Claire, "whenever we
boil a pot of potatoes or chestnuts or beans? I did n't
know we were so clever; but I for my part shall not put
on any airs, as it is n't very hard to make a pot
boil."
"Man's ingenuity has devised a more effective means
than heat alone for converting starch into sugar. The
starch is boiled in water and, while it is boiling,
there is added a small quantity of a powerful liquid
called oil of vitriol or sulphuric acid. This causes
the starch to turn to syrup, after which the oil of
vitriol is of course removed. It has done its office.
The substance thus obtained is soft, sticky, and nearly
as sweet as honey; it is called starch-sugar, or
glucose, and is much used by confectioners. As I have
already told you, the sugarplums and other sweets that
you buy at the candy shop are in most instances the
product of this ingenious process of turning starch
into sugar. And so you see the humble potato furnishes
you with something besides the modest dish you find
every day on the table.
"But that is not the whole story. Glucose, obtained as
I have described, is exactly the same as the sweet part
of ripe grapes. With potatoes, water, and a few drops
of sulphuric acid there is artificially produced, in
enormous boilers, the same sweet substance that nature
manufactures by the action of the
[273] sun's rays on the full-grown grape. Now, since
grape-sugar turns to alcohol by fermenting,
starch-sugar ought to undergo a like transformation. As
a matter of fact, in northern countries, where the
climate is too cold for the vine, alcoholic liquors are
made from starch that has first been changed to sugar.
Such liquors bear the generic name of potato-brandy,
though all seeds and roots rich in starch may be used
in the same way as the potato."
"Let us now drop the subject of potato-brandy, which I
have briefly touched upon to satisfy your curiosity,
and return to matters of household economy. There are
various starchy substances that are much used in making
soup, chief among them being the starch of potatoes,
which furnishes a nourishing and appetizing dish of
this sort and is our most important, least expensive,
and most widely distributed food product of its kind.
Many of the starchy preparations bearing pretentious
names are really nothing but this, at least in part.
Other forms of the same essential substance appear more
rarely on our tables, their higher price causing them
to be reserved for dyspeptics and convalescents. Let us
consider for a moment the chief of these.
"In South America there is cultivated a large
farinaceous root called manioc, which in its natural
state is a deadly poison to man, but which nevertheless
furnishes material for excellent bread. First the root
is reduced to pulp with a grater, after which the juice
is squeezed out, and with the juice goes the poison,
leaving a harmless substance rich in starch and serving
as the principal article of food for the
[274] poor in a country too hot for raising wheat. This
farinaceous substance is sold with us under the name of
tapioca. A spoonful of tapioca is transformed by the
action of boiling water into a rich jelly of exquisite
fineness.
"The woods and meadows of our own latitude abound in
certain plants known as orchids, remarkable for their
oddly shaped flowers and for the two small tubers of
the size of pigeons' eggs in the midst of the fine
roots of the plant. These tubers contain starch. They
are gathered in eastern countries, and flour made from
them comes to us under the name of salep or salop.
Prepared with hot water, it furnishes a gummy jelly
suitable for the use of invalids.
FLOWERING ORCHID
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"Palm-trees grow only in a hot climate. The trunk of a
palm is a graceful column, without branches, of lofty
height, tapering but little from the bottom to top, and
crowned with an enormous tuft of large leaves. One of
these trees, the sago-palm, has the heart of the trunk
filled with a farinaceous pith which is removed after
the tree is cut down. From this pith is obtained a
starchy substance known as sago and differing only
slightly from potato starch.
"These strange forms of starch, which excite our
curiosity but are of no great use to us, must not make
[275] us forget the farinaceous matter furnished by our own
leguminous plants, lentils, beans, and peas. You know
the excellent thick soup we make of dried peas, and you
doubtless also know how disagreeable are the hulls of
this vegetable, tough as parchment and without taste or
nourishment."
"Yes," replied Emile, "if it were not for those horrid
hulls, dried peas would n't be at all bad."
"The hulls, however, are got rid of by pouring the soup
into a colander, which retains the objectionable part
and lets through the pure pulp. But in the process a
certain quantity of nutritive matter mixed with the
hulls is lost.
"Invention and experiment have done away with this
loss. The peas are steeped a few minutes in boiling
water to burst the hulls, after which the peas are
dried in an oven and then made to pass between two
millstones sufficiently far apart to remove the hulls
without touching their contents. Thus freed of their
tough exterior, the peas are ground to powder, which
goes under the name of pea starch. In similar manner
are obtained bean starch and lentil starch. All these
preparations are used for making soup, and all have the
qualities, without the defects, of the vegetables from
which they are derived; that is, they are freed from
the disagreeable hulls that fatigue the stomach to no
purpose.
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