Improvements in Thawing Frozen Food.
Year: 1894

page_text: Date of Application, 3rd Sept., 1894
Complete Specification Left, 8th Mar., 1995-Accepted, 4th May, 1895
Improvements in Thawing Frozen Food.
I, EDWARD MONTAGUE NELSON, of 15. Dowgate Hill, in the City of London,
Gentleman, do hereby declare the nature of this invention to be as follows:-
The object to be attained by this invention is the thawing of frozen food
substances and especially of frozen meat in a better manner than hitherto and so
that in the process of thawing, the surface in the case of meat shall not become
discoloured by the deposition upon it of moisture from the atmosphere in which it is
being thawed and, further, so that the amount of loss of weight due to that which is
known as "bleeding away " from the meat during and after thawing may be rendered
as little as possible.
I attain this object by providing that the air which comes in contact with the
surface of the meat, shall, at all times, during the thawing, contain so little moisture,
no matter what its temperature may be, that it will not deposit a dampness on the
ineat surface.
As the thawing goes on and the surface of the meat rises in temperature, I provide
that the. humidity of the air, also gradually increased in temperature, shall be so
regulated, that while on the one hand, it shall not deposit its moisture upon the
surface of the meat, on the other hand, it shall not be so dry as to abstract largely,
moisture from that surface, thereby diminishing the saleable weight.
With the view of saving first cost and also of diminishing the expenses attendant
upon working, I so construct my apparatus that I cause the air to circulate iu
the thawing room by simple means, which may be called natural means by raising
or lowering its temperature either at the top or the bottom of the room as may be
required.
1 find it convenient to proceed as follows:-During the process of thawing any
given quantity of meat, I do not change the air in the room either by the removal
of any of it, nor by the addition of fresh air from outside, but I keep the thawing
room practically hermetically closed, and I first subject the air in it before the
meat is put in to a reduction of temperature to a point considerably below that of
the meat to be thawed. I obtain this reduction by the employment of pipes
containing ammouia capable of being expanded in those pipes or containing cold
brine or glycerine, or any other suitable refrigerating medium as is now well
understood.
The air is thereupon thoroughly dried, depositing a large portion of its moisture
which is drained to the outside of the room in any well known manner, and it is
then fit to be heated up by being passed over hot water or steam pipes or other dry
heated surfaces. When such dried and suitably heated air is permitted to come
in contact with the frozen meat, the surface of which it will be remembered
although frozen, is at a considerably higher temperature than that to which the air
was reduced when it deposited its moisture, the result will be that this air while
gradually warming up the meat from the surface inwards, will never be able to
deposit moisture upon that surface, nor if the dryness of the air is properly
regulated will it extract moisture from it to any great extent and the needed
circulation will be naturally obtained by reason of the superior levity of the
warmed air.
From the foregoing description, it will be obvious that my invention does not

page_text: require the employment of any mechanically worked apparatus for circulating
the air.
Dated the 3rd day of September 1894.
G. F. REDFERN & Co.,
4, South Street, Finsbury, London, Agents for the Applicant.
Improvements in Thawing Frozen Food.
I, EDWARD MONTAGUE NELSON, of 15, Dowgate Hill, in the City of London,
Gentleman, do hereby declare the nature of this invention and in what manner
the same is to be performed, to be particularly described and ascertained in and
by the following statement:-
The object to be attained by this invention is the thawing, of frozen food
substances and especially of frozen meat in a better manner than hitherto and
so that in the process of thawing, the surface, in the case of meat, shall not become
discoloured by the deposition upon it of moisture from the atmosphere in which it
is being thawed and, further, so that the amount of loss of weight due to that which
is known as "bleeding away "from the meat during and after thawing may be as
little as possible.
I attain this object by providing that the air which comes in contact with the
surface of the meat, shall, at all times, during the thawing, contain so little
moisture, no matter what its temperature may be, that it will not deposit a dampness
on the meat surface.
As the thawing goes on and the surface of the meat rises in temperature, I
provide that the humidity of the air, also gradually increased in temperature, shall
be so regulated that, while, on the one hand, it shall not deposit its moisture upon
the surface of the meat, on the other hand, it shall not be so dry as to abstract
largely moisture from that surface, thereby diminishing the saleable weight.
With the view of saving first cost and also of diminishing the expenses attendant
upon working, I cause air to circulate in the room or chamber in which the
thawing is effected by simple means, which may be called natural means, by
raising or lowering its temperature either at the top or the bottom of the room as
may be required.
a
find it convenient to proceed as follows:- During the process of thawing any
given quantity of meat, I do not change the air in the room either by the removal
of any of it, or by the addition of fresh air from outside, but I keep the thawing
room practically hermetically closed. Before the meat is put into the room or
chamber I reduce the temperature of the air therein to a point considerably below
that of the meat to be thawed, preferably by the employment of pipes into which
ammonia is allowed to expand or containing cold brine or glycerine, or any other
suitable refrigerating medium as is now well understood, whereby the air deposits
large portion of its moisture which is drained to the outside of the room in any well
known manner. The air thus more or less dried is now heated (that is to say, its
temperature is raised above the temperature of the substances to be thawed which
are now put into the chamber) by being passed over hot water or steam pipes or
other dry heated surfaces and comes in contact with the frozen meat (the surface
of which it will be remembered, although frozen is at a considerably higher tempe-
rature than that to which the air was reduced when it deposited its moisture) the
result of which is that this air, while gradually warming up the meat from the
surface inwards, will never be able to deposit moisture upon that surface, nor if
the dryness of the air is properly regulated will it extract moisture from it to any
great extent, and the needed circulation will be naturally obtained by reason of the
superior levity of the warmed air.

page_text: From the foregoing description, it will be obvious that my invention does not
require the employment of any mechanically worked apparatus for circulating
the air.
Apparatus suitable for carrying my invention into practice is shewn in the
accompanying drawings, in which :-
Figure 1 is a perspective view of a chamber having heating and cooling pipes
therein, the wall provided with the door being omitted to show the interior:
Figure 2 is a longitudinal section of the same, and,
Figure 3 is a sectional plan.
a, a are the walls of the chamber which are preferably made double or jacketted
in order to prevent the air within the chamber from being affected by the outsido
temperature. b, bare heating coils each of which is connected at one end to a
steam or hot water pipe c or the like and at the other end to a pipe d through
which the heating medium is discharged after passing through the coils, each of the
said coils being provided with a cock or cocks for permitting the supply of steam
to be shut off whereby the temperature within the chamber may be regulated as
required according to the number of coils in use. As shewn in the drawings these
coils are arranged beneath the floor e of the chamber, which floor is composed of
bais or slats having spaces between them so as to allow of the circulation of the
air in contact with the heating pipes.
f, fare coils arranged at the sides of the chamber through which a freezing
mixture is caused to circulate for the purpose of condensing upon their surfaces
any moisture contained by the air in the said chamber, and g, g are bars carrying
hooks upon which the food to be thawed can be suspended.
It will be understood that the dryness of the air will depend upon the
temperature of the cooling surface the cooler the surface the dryer being the air
and vice versa.
h, hare screens each of which is advantageously composed of two sheets or
pieces of flexible material, such as canvas, suspended from the roof of the chamber,
the said screens serving to prevent the extreme coolness of the pipes f, f from
retarding the thawing of the food in proximity to the said pipes and also to cause
the currents of air to pass in a regular direction. i, i are troughs which extend to
the outside of the apparatus and which serve for collecting and discharging the
water of condensation which may drop from the freezing pipes f, f.
It will be understood that in using the apparatus the temperature within the
chamber will be raised sufficiently by means of the heating pipes to gradually thaw
the food and that the warm dry air, rising between the slats in the floor, after
having taken up some of the moisture given off by the meat during the thawing
process, passes around the ends of the screens . into contact with the pipes f,f
upon which the moisture contained by the air is condensed, the air thence passing
down under the screens into contact with the heating pipes whereby it is more or
less warmed so that it again is caused to rise.
Having now particularly described and ascertained the nature of my said inven-
tion and in what manner the same is to be performed, I declare that what I
claim is :-
1. The improvements in thawing frozen food consisting in subjecting such food
to a temperature above freezing point in the presence of cold surfaces upon which
the moisture contained by the air is condensed substantially as described.
2. In apparatus for thawing frozen food the arrangement in a closed chamber of
pipes through which a heating medium is circulated and of other pipes through
which a cooling medium is circulated, substantially as described.
Dated 0 1
G. F. REDFERN & Co.,
4, South Street, Finsbury, London, Agents for the Applicant.