The Delaware farmer., 1883-08-31
AGRICULTURAL.
Bleaching EvapOrated Fruit.

fact that evapOrated fruit is losing favor with IN
public, through its flavor being destroyed o
changed in the process OF bleaching or setting 0
color as it is sometimes called. This is at best
very foolish practice, aud is ouly done becaus
public taste requires thatthe eve shall be please,
at the expense OF the palate, which in this mat
ter is but OF small importance as the natural col
or Of the dried irut is not offensive to the eye
and no one who eats, not alone TO merely fiji uI
an empty VOID in his stomach, but in addition to
derive from his gustatOry nerves similar pleas
ures to those derived through his optic nerves
from harmony of color, through his auditory
nerves from music. and through his olfactory
nerves from delicious OdorS, will object to the
color Of unb.eached evaporated fruit He will
care far more for the flavor than the color But
a depraved public taste call for color, and those
who evaporare fruit must pander TO it or lose the
sale Of their goods. Hence if the public desire
light color and flavor both, it is matter of i'm.
portance to discover whether there is not some.
thing wrong in the process OF bleaching, which
hus produces an unpleasant flavor in the fruit.
The bleaching process is based upon the well
known fact that sulphurOus acid gas does 10;
certain length of time, remove Or destroy the
color of any organic substanees with which it
comes IN contact, especially if they are vegeta-
bic. Thislt does, without destroying the color
ing matter OF the substance, as chlorine does, for
if we apply a stranger acid we can restore the
color. Water has great affinity for this gas,
and will absorb about fifty times its volume of
it. when exposed to the air either in its gaseous
state, or in It's aqueous solution it gradually abb
,,,II
phuric acid, or oil OF vitriOl. The addition of
nitrous acid to sulphurous acid will also convert
it into sulphuric acid.
The ordinary mode OF bleaching, is to place the
fruit at the close Of the drying process, in air
tight chambers in which is also placed a vessel
containing roll birthstone in state of cOmbus.
tiOn. When burning, it gives offsulphurous acid
which by coming in contact with the atmos-
phere is to large extent converted into sulphur
ic acid, this conversion is doubt largely aided
by the high temperature of the chamber The
action of he sulphuric acid destroys the ccllu-
lose or cell-structure of the fruit in the
same way that 1t destroys the similar cell
structures in a piece OF wood, charming |
it, and making it like piece Of punk. Ttis |
is the reason why by the Old way Of bleaching |
while the fruit is drying over the heater, shat
the wooden flue of the evaporator is so liable to
burst into fame The wood work becomes car.
BOMBED and so changed in its character that it is
liable to ignite at any moment. Under this pro-
cess however, the water from the fruit is sent off
in state Of highly heated vapOr, aud as the
acid has great affinity for water, it is taken up
by the vapor, and escapes through the shaft into
the open air. Its afiuity for water being greater
than for the substance of the fruit it is carried
off and thus does not so seriously affect the fruit
the unchanged sulphurous acid bleaching it. In
the newer process the water Of the fruit being
nearly ALL if not entirely driven off. there is but
little vapor to take up the suphuric acid pro-
duced by the action Of the air on the sulphurous
acid, and it is thus left free to attack the sub.
stance of the fruit.
SulphurOus acid for this purpose would prOba-
ply be better produced by heating in a q ass re- .
tort, equal parts Of powdered black oxide of man.
ganese and flowers Of sulphur, and letting the !,
resulting sulphurOus acid escape from the nozzle
Of the retOrt into the chamber containing the
fruit. In this process, the sulphur attacts from
the black oxide Of manganese-it is more prop. . :
erly speaking a perOxide-a portion of its oxy-
gen, and the sulphurOus acid is the result As =
this is done at a much lower degree Of heat
than that at which the sulphur burns, sulphuric .
acid would not be so readily produced by the :
contact of the suphurous acid with the atmos. ~
Dhere in the chamber. This might be still fur. :
her obviated, by conducting the bleaching pro- =, -
less in air.tight chambers, from which the air -
lad been exhausted by means Of an air pump. :"
The present mode of bleaching is very crude, p
ind some more scientific and precise way of do - :,
ng it, must be adopted better results are to be %
btained. ~
To show how different degrees of heat affect a. =.
uiphur and its products we would state that at
SO degrees F. 1t sublimes, and strongly exhibit y,
IS peculiar OdOr; at 100 degrees it becomes high
mhammable burning slowly with faint blue
anne, and combining with the oxygen of the air; ~
t 800 degrees It's combustion goes on rapidly -
18th much evolution Of lighttaud heat. It mets
226 degrees, becomes thin, and fluid like wat
r, and Of light amber color; between 43O and q,
30 degrees it becomes yiscid and tenacious, and ~
about 600 degrees,-its boiling potnt-it again -,
ecomes liquid. -,
Beyond however, the mere bleaching effect of
e sulphurous acid, its effect upon the pectose, =
ueose, and other constitutuent parts of the ~.
nit should be investigated and considered. ''l9
he subject Is a somewhat intricate one, involv- -
g many complex chemical changes and COM
nations, such as have to be investigated in the =
aking Of sorghum sugar, wines, etc. Those NIT
gagged in evaporating fruit should jointly en- fe
~ an expert chemist in this line of investiga-
n, to study the process, and so arrive at the WI
st methods for doing it properly. so 80
MARKET GARDENING. M