Improvements in Bread and the like, in the Process of Raising and Baking same, and in Ovens therefor.
Year: 1890

page_text: Date of Application, 14th Nov., 1890-Accepted, 20th Dec., 1890
COMPLETE SPECIFICATION.
Improvements in Bread and the like, in the Process of Raising and
Baking same, and in Ovens therefor.
We, THOMAS RICKETT, Mechanical Engineer, of 17 Torriano Avenue Camden
Road, in the County of Middlesex, and Thaddeus HYATT of 9 Farringdon Road in
the City of London, Pavement Light Manufacturer, 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 :-
Our invention is an improvement upon a prior one patented to one of us, (the said
T. Rickett) on the 9th day of March 1887 and now designated by the amended
No. 3597* of 1887 for "Improvements in the process of bread raising and baking
and in ovens therefor"; wherein the steam which raises the dough is generated
within it by the heat of the oven from the water or liquid of the dough itself.
To make clear the nature of our present improvement requires an explanation of
that invention. In the steam-raised bread, produced by the aforesaid invention the
heat of the oven is the originating cause of the lightness of the bread; for it is the
heat of the oven that transforms the liquid portion of the dough into steam; to do
which, requires that the dough itself be heated to a boiling point. In the open air
212 degrees is the boiling point; the pressure of the atmosphere being 15 lbs. to the
square inch. But water would boil at as low a degree of heat as 70°, could the whole
of this pressure be removed; which practically is impossible.
The lightness of dough is due to the bread cells, and the bread cells are created
in virtue of a certain india rubber like elasticity and toughness in the dough that
holds gas or vapour causing the dough to expand with the expansion of the gas or
vapour until the dough gets to a temperature of about 140 degrees; after which
the bread cells cannot be created, for the dough is then like putty; short and plastic,
and incapable of expansion.
To make use then of the water of the dough in the form of vapour to raise the
bread, the water must be boiled or vaporized below about 140°; and this means that
the pressure of the atmosphere requires to some extent to he removed. The vacuum
oven described in the Specification to Patent No. 3597* aforesaid, is the apparatus
employed to do this work; and our present invention relates to an improvement on or
connected with same.
The difficulty found in practically working the oven, is, that the vapour rising from the
bread is not carried away fast enough to cause the interior of the loaf to be sufficiently
dry by the time the outside is fully done; the consequence of which is, that the outside
becomes overdone, when the loaves are kept in after removal of vacuum for the
purpose of drying out the interior; while if the vacuum be removed before the out-
side is well hardened, the letting in of air increases the pressure and thus tends to
break down the weak bread-cells, and spoil the bread.
For the purpose of overcoming this difficulty we now propose to produce as we
term it an "aerified vacuum by letting a regulated quantity of air into the oven
from the time the air pump is started or soon after. This does not destroy the
vacuum but allows of it being maintained at a fixed indicated number of pounds
during the working of the air pump.
The theory upon which our present invention proceeds is, that a certain quantity of
dry air is required by every loaf in baking, to carry off its moisture. In the common
oven there is an abundance of air; but in a vacuum oven, the supply is limited
by what on the face of it, appears to be a requirement of vacuum creation viz. :-an
air-tight chamber or oven. This air-tight oven is necessary for the purpose of
maintaining a vacuum, but we find that at the same time we require the presence
in said oven of a certain amount of air in a moving condition to carry off the
moisture of the dough.

page_text: We therefore provide the oven with an air inlet of some suitable description by
which a regulated quantity of atmospheric air can be admitted into the oven without
lowering the point of vacuum which we wish to maintain this being kept up by
causing the air pump to work at such an increased speed as is necessary to maintain
the point desired.
In this manner we obtain a current of dry air continually passing into the oven
and being continually exhausted by the pump said air carrying away with it the
moisture arising from the dough. We would repeat however that it is a vacuum
which we maintain though a vacuum in a condition which we term "aerified.”
"
To produce this "aerified vacuum
suitable for the purpose but we prefer to employ the combined air tap and indicating
we may employ a tap, valve or other device
dial illustrated in the accompanying drawings
which
Fig. 1 is a side elevation of the oven stack having two ovens.
Fig. 2 is an end elevation of saire shewing it together with the air pump, condenser,
steam boiler and connections.
Fig. 3 is a side sectional elevation of one of the ovens on an enlarged scale shewing
the inlet applied thereto.
Fig. 4 is a face view in a still larger scale of the combined air tap and indicating
dial we employ.
Fig. 5 is a side sectional elevation of same attached to the oven and
Fig. 6 is a side view of part of same in elevation.
In the drawings A A indicate the vacunm ovens. B is the steam boiler for
supplying with steam the cylinder C of the air pump D, a, b being the live steam and
exhaust pipes respectively. E is an air-tight chest forming also a drip chamber for
the water of condensation from the coiled pipe or worm d situated in a water tank G.
To the coil d is attached the pipe d' with its branches d" d" which are connected to
the ovens A A.
In this way the pump D exhausting air through the suction pipe C chest E cooling
worm d and pipes d' d will produce and maintain a vacuum in the ovens A A. A
sight glass e is provided in the door I so that the progress of the baking may be
inspected.
For the purpose of admitting air into the ovens we affix, preferably at the door I
a dial plate J having combined therewith an air tap K to which is attached an index
finger. This index finger is secured in place by a nut h which is screwed down on
the end of the tap. An air passage i is formed through the length of the tap, said
passage having a right angled bend in same as shewn in Fig. 5 the inlet point o of
said passage being covered by the projecting portion or highest point of the bevelled
or screw like shoulder M of the dial J when the index finger is at the position shewn
in Figs. 4 and 5. The inner end of the tap K is held in the socket in which it turns
by the nut screwed on the end of same.
The dial J may be divided up as desired. As shewn in Figs. 4 and 5 the index
finger is at zero and the inlet o of the passage i is consequently closed so that a
full vacuum would be maintained in the oven. When the finger f is turned around
to the point marked "one quarter" the tap K will be turned around and the opening o
be one quarter uncovered from the shoulder M as shewn in Fig. 6, and a small stream
of air will be admitted into the oven. The shoulder M gradually decreases as shewn
in dotted lines in Fig. 6 so that when the tap is turned around to the point marked
with a * on the dial the opening o will be fully uncovered and the greatest quantity of
air the passage i will take will be passing into the oven.
By means of the above device a regulated quantity of air may be admitted into the
oven to suit the particular baking in progress as experience shews that the quantity
of air required is not the same with all bakings and requires to be varied according to
the different goods. The index may therefore be set at each baking if required to a
point fixed by experience to produce the best result.
It will be evident that this oven may be employed with advantage not only for
baking dough which is raised solely by the steam given off from the moisture
contained therein without any chemical action but also for dough prepared in the

page_text: "
ordinary or in known manners such as when containing chemical substances as
carbonated water or baking powders. In the latter case the "aerified vacuum
assists materially in raising the dough by transforming the contained moisture into
steam in addition to the result due to the chemical action arising from the use of the
chemical substance, baking powder or the like.
Having now particularly described and ascertained the nature of our said inven-
tion and in what manner the same is to be performed, we declare that what we
claim is:-
1. The improved process of baking dough wherein the latter is raised and baked
in a vacuum oven into which a small quantity of air is admitted, substantially as
described.
2. The improved vacuum oven for baking dough having a tap or inlet for admitting
a regulated quantity of air into same substantially as and for the purpose described.
3. The improved vacuum oven having a tap or inlet for admitting a regulated
quantity of air into same and an indicating finger and dial substantially as and for
the purpose described.
4. As a new article of manufacture the product resulting from the use of an
"aerified" vacuum oven substantially as described.
5. As a new article of manufacture the product resulting from the use of an
"aerified'
vacuum oven when treating dough prepared in the ordinary or known
manners.
ני
Dated this 14th day of November 1890.
PHILIP M. JUSTICE,
55 & 56, Chancery Lane, London, Agent for the Applicants.