IMPROVEMENTS IN THE CLARIFICATION AND PRESERVATION OF THE EXPRESSED JUICES OF FRUITS."
Year: 1882

page_text: PROVISIONAL SPECIFICATION left by Samuel Cleland Davidson at the
Office of the Commissioners of Patents on the 3rd February 1882.
1
SAMUEL CLELAND DAVIDSON of Belfast in the County of Antrim, Ireland,
Merchant. IMPROVEMENTS IN THE CLARIFICATION AND PRESERVATION OF THE
EXPRESSED JUICES OF FRUITS."
The improvements as hereinafter described are applicable generally to the juices
of such edible fruits as yield when pressed a thin fluid juice such for instance as the
fruits of the lemon, orange, raspberry or current species, and the clarified liquids
obtained as hereinafter described will keep good for an indefinite period and have
a bright attractive appearance with more or less color according to the fruit employed;
they will posses nearly all the characteristic flavour and aroina of the fruit and may
be used for beverages, in some instances alone, or diluted with water to any suitable
degree, or diluted with water charged with carbonic acid gas under pressure in bottles
to form effervescing or sparkling beverages.
The fruits employed, which must be in fresh and good condition are sliced, cut or
pressed either with or without the skin being removed and in any convenient way
to just such an extent that all the cells containing the juices may get cut open, or
burst sufficiently to allow the juice to get out.
To the sliced up or pulped mass I then add water, preferably cold, equal to about
double the amount of pure undiluted juice which the fruit would yield, and I stir
it in for a short time and then strain the whole through any convenient form of
strainer or filter such as a very fine sieve or a bag filter in order to separate and
remove the principal bulk of the solid matter of the fruit and obtain the juice as free
as possible from such matter. If however the fruit used is of such a nature that
when so cut up or pressed the liberated juice is sufficiently fluid to filter freely
of itself from the solid matter of the fruit no dilution with water need then be
necessary.
To the juice when filtered from the solid matter of the fruit I then add an amount
of tannic acid in solution sufficient to produce in the liquid a flocculent precipitation
or clouding stirring the liquid well while applying same, and afterwards for about
from half an hour to one hour. I then add and stir in an aqueous solution of gelatine
containing an amount of gelatine which in its dry state would be equal inore or less
to about from half to one grain of gelatine to each fluid ounce of the fruit juice
liquid.

page_text: This solution of gelatine I preferably use of a strength equal to about 3 or 4
grains of gelatine to the ounce of water and preferably add it lukewarm. On stirring
this into the liquid an extensive flocculent precipitate will immediately form up
gathering with it the precipitation or turbid clouding matter formed by the preceding
treatment with tannic acid and after being stirred gently and continuously for about
a quarter of an hour longer the liquid may then be filtered free of this precipitated
matter, and a convenient form-of-filter to use for this purpose is the ordinary bag
filter of close well woven cotton cloth. In some instances, this precipitation can be
removed by decantation, but filtration is usually preferable.
On pouring the liquid into the bags the first of it which passes through if not
quite froe from clouding matter should be returned, and if the tannic acid and
gelatine treatments have been done sufficiently the liquid should soon filter through
pure and free from any cloudy appearance whatever.
To the filtered liquid I then add and stir in salicylic acid, but as this acid is of a
difficultly soluble nature in cold liquids of this sort I preferably add it dissolved
in hot aqueous solution stirring it into the liquid vigorously while being added.
The amount of salicylic acid to use varies with different juices, but I generally
find that about to 1 grain of it por ounce of the fruit juice liquid is sufficient to
ensure its keeping qualities provided the tannic acid and gelatino processes have
been properly and sufficiently carried out.
The liquid should now be retained at as low a temperature as possible preferably
between 50° and 60° Fahrenheit and if after a few days' keeping it should again
show somewhat dull and cloudy it should be again treated with a small addition of
the gelatine solution and be re-filtered, after which a slight further addition of
salicylic acid is useful, equal to about an eighth or a quarter of the amount first
added.
The clarified juices are then ready for use and may be mixed with hot or cold
water to form beverages or if diluted with cold water to a suitable extent they may
be bottled like wines and used similarly or they may be bottled in combination
with water charged with carbonic acid gas under pressure to form sparkling and
effervescing beverages having much of the characteristic flavour and qualities of the
fruits from which the juices were expressed.
In the preparation of these fruit juice liquids it is preferable to employ water
containing sulphate of lime in solution, or if the water be deficient in this respect
it should be artificially "hardened" by adding powdered gypsum to it beforehand.
Should the clarified juices be required sweet it is preferable to add the sugar in
most cases to the juice after being filtered free from the solid matter of the fruit,
stirring it in till dissolved before adding the tannic acid solution.
In the preparation of the tannic acid solution I find it desirable to employ water
that is naturally "hard" or that has been artificially hardened by the addition of
gypsum and I further find it desirable to dissolve in the solution along with the
tannic acid an amount of sugar equal to about double the weight of the dry tannic
acid used, and the solution should then be boiled till the peculiar smell which usually
accompanies tannic acid is sufficiently driven off to be scarcely if at all noticeable
in the solution when cold and the solution is to be employed cold or nearly so.
With some fruit juices the gelatino solution may be added before the tannic acid
but I usually prefer adding the tannic acid first.
With the juices of some fruits bi-sulphite of lime may be added as a preservative
instead of salicylic acid, but the salicylic acid is usually preferable.