The Delaware farmer., 1883-11-23
Acids in Fruits.

ana Sulpnuflc aclu. we nave seen
that this action can be hastened by in
creasing the degree of heat. or by in
creasing he quantity of acid. Nature
provides acids in fruits and vegetables
for this purpose; through their action
and that OF the summer heat the
starch and similar matters contained
in the unripe fruit is gradually con
verted into the various sugars and the
fruit gradually becomes sweet. We
only adopt natures process when we
add sulphuric acid, and apply heat to
the staIch when we make glucose.
There are great number Of these
vegetable acids known to chemists,
but in the fruits and vegetables geuer-
ally grown with us the following are
the principal. MALIC ACID, found in
the apple, ,currants, gOOseberres, plums,
cherries, strawberries barberries, and
nearly all of our common fruits. 1t
is also found in rhubarb, tobacco leaves,
and in maple sugar. TARTARIC ACID
is found most abundant in grapes, but
is also found in potatoes, pine-apples,
cucumbers, sumach berries tamarinds,
and several other fruits. CITRIC ACID,
the distinguishing acid of the lemon,
is found in all fruits of the lemon, and
orange family, and in unripe tomatoes,
1t is found with malic acid in straw
berries, raspberries, gOOseberries, cur
rants and cherries, and in small guam
titles in the bulbs of onions, beet roots,
Jerusalem artichOkes, coffee berries and
pine needles. OXALIC ACID, general
lly known as salt of sOirel, common
ly used for removing ink-stains, gives
the peculiar acid taste to wood sOrrel,
and to sour grass as it is commonly
called. The mature leaves AID roots
of the beet, and the roots of the rhub-
arb or pie-plant, yield it in large guam
titles, and it probably exists in most
plants when they are in a growing
state.
Besides the above mentioned acids,
there is also found in fruits and some
vegetables three other acids of peculiar
character. These are known as pee
tosic poetic, and metaptctic acids.
The first two compose jellies. They
are insOluble in cold water. Poetic |
acid is insOluble in boiling w ter, but |
pectOsic acid is soluble in it, but gelat- |
iniZes again when cold Metapectic /
acid is formed from pectOsic and pee /
tic acid by subiecting them to long /
boiling, or by exposing them to the /
action of acids or alknlies. 1t does /
not gelatinize. Housewives know |
that by boiling the juice of currants or
of other fruits for too long time it
will not make Jelly. This is because of
the transformation of the pectOsic and
poetic acids into metapectic acid.
PectOsic and poetic acids are indi-
rectly derived from pectOse, peculiar
substance which is known to exist IN
fruits and many of the roots of our cul-
tivated vegetables, but always in con-
nection with cellulose, or in cOmbina-
ton with it, but it never has been OBJ
tained separately. From it is pro-
duced pectin, much in the same way
as dextrn is obtained from celluose
or starch, that is, by the action of heat,
acids, and ferments. When dissolved
in water it is viscid and gummy. The
Juice which eXudes from baked apples
or pears, is a strong solution of pectin
in water. From this pectin are direct
ly derived the hceeacids above named.
None of these pectOse bodies can be
transformed into any of the varieties
of sugar.
1t will thus be seen from what we
have previously said, that fruits are
composed of, or contain various cOU-
stituents, which under certain circum-
stances from very complex cOmbina-
=
based on chemical action and reaction.
The whole subject is one which has
not as vet been as thoroughly investi-
gated as it should be by chemists. 1t
behOOves all those interested in the
business of evaporating fruit to inves-
tigate it, or to have it investigated by
some experienced analytical chemist.
In such a delicate operation as that of
properly evapOrating fruit, the rule of
thumb will not do. To do il profta-
blV requires such modes of operating
as are based upon a knowledge of the
processes of nature. The merely so
called practical man is one who works
in the dark in happy-gO-lucky way.
He may succeed sometimes. but his
failures far overbalance his successes.
We are convinced that the present
mode of evapOrating fruit is faulty to
great degree, and that the best and
most profitable results are not obtained
by it. The fruit is exposed to too
great heat, which induces injurious
chemical changes in the constituents
of the fruit, This is also aggravated
by the fruit in the upper sieves of the
stack being exposed to the hot vapOr
from the fruit in the lower sleeves. In
other words the fruit is partially cooked
instead of being dried. When pre-
pared for the table it is again cooked,
and anything re-cOOked always loses
its piquancy of flavor. Excellent as
evanoTated fruit is, we have never yet
tasted any of it that had the proper
fruit flavor preserved in it, as we'll as
we have known it to be preserved in
carefully and properly sundried fruit
Delaware has an agricultural college.
Here is a great, and growing industry,
capable of being greatly extended,
which should form a subject of study
and investigation by some member or
members of its Faculty. The Evapo-
-. . A ssOoiofiOn shOnId take it, nm