Note: Descriptions are shown in the official language in which they were submitted.
This invention relates, generally, ~o bakery sys-tems
for preparing, storing and retail sale of bakery foods and to
a method for recons~ituting frozen bakery foods in such a system.
There exists a need for a commercial bakery system in
which bakery foods are produced in large quantities in a central
bakery7 frozen, and distributed to retail sales outlets where the
bakery foods are reconstitu-ted to their original quality and '
characteristics. Bakery foods are generally understood to be
foods prepared from grains9 such as corn, wheats~ oats, usually
in combination with leavèning agents in the form of yeast,
entrapped air and/or bicarbonates and subjected to hea~ for the
purpose o forming the structure of the bakery food and providing
stability. Various ingredients may be added to produce refinements
in flavor and character of finished product. Examples ~re dough-
nats, cakes, sweet doughs and rolls. The centralization of the
bakery process provides cost control, uniformity of product quality,
and eliminates the need for space consuming equipment and skilled
personnel at the retail sales outlets.
Problems which exist in establishing such a system
are the reconstitution of the frozen bakery food at the retail
outlet and the relatively short shelf life of the bakery foods.
In~the past, ambient thawing, oven thawing, or a combination
of ambient and oven thawing have been used for reconstituting
bakery foods. Each of these methods has serious drawbacks,
particularly for a commercial bakery system. Ambient thawing,
for example, requires a relatively long time which accelerates
staling and which varies from product to product, making inventory
control difficult. Final product quality is usually poor, with
the crust soggy and icings and glazes often wet, sticky and
un-uniform in appearance. Oven thawing, on the other hand,
-2-
: :
~1~)6~63~
requires considerably less time; however, the crusts of oven-
thawed foods are generally excessively dry and icings often
melt due ~o the high oven temperatures be~ore the product is
fully thawed In addition, with filled products such as
jelly doughnuts, the outside of the product must become very
hot in order to thaw the inner filling resulting in greater
drying and possible burning of such products. Combined oven
and ambient thawing, while providing some a-dvantages over the
individual thawing methods, has not been found in general to
provide a commercially acceptable reconstituted product because
of poor inventory control and variable quality of the reconsti-
tuted product.
Microwave baking technology has provided a new approach
to the reconstitution of frozen bakery foods. In microwave
reconstitution, the bakery food is exposed to microwaves either
alone, or with an infrared ambient~ in a microwave cavity or
oven. Reconstitution in this manner is very rapid, requiring
as little as thirty seconds for bakery foods. However, microwaves
do not act uniformly within the microwave cavity or within the
products in the cavity, resulting in fully thawed, burned, and
completely frozen food side-by-side or within a single food item
in the microwave cavity at the end of reconstitution. This is
an example of the well known "runaway effect." In addition,
microwaves cannot reconstitute glazes or icings on the bakery
food and crusts are not as crisp as the freshly prepared food.
Attempts to overcome these problems, încluding using pulsing
.. .. . . ..
~6~ ~ 3~
- microwaves and dummy loads in the microwave cavity to absorb
excess microwave power, have not been successEul.
Accordingly, it is an object of the invention to
provide an improved bakery system for supplying bakery foods
Erom a central bakery to retail sales-o~ltle-ts. It is a further
object of the invention to supply frozen bakery Eoods from a
central bakery which can be reconstituted at the retail sales
outlets.
It is a still further object of the invention to pro-
~10 vide r-econstitu~ed frozen bakery foods which are similar in
characteristics and quality to freshly prepared foods. Another
object of the invention is to reconstitute~frozen bakery foods
in a controlled manner to provide uniform foods having a long
shelf life.
A further object of the invention is to provide a
reconstitution process which is characterized by relatively
short reconstitution time, uniformity and high quality of the
reconstituted bakery foods, relatively low cost and adaptability
to a wide range of bakery foods.
These and other objects are carried out according to
the present invention which enables the establishment o~ a
commercial bakery system in which bakery foods are prepared at
a central bakery, frozen and transported to retail sales outlets
where the frozen bakery foods are reconstituted under controlled
conditions to the same qualities of taste, texture~ appearance
and moisture as freshly prepared bakery foods. Reconstitution
_~_
::
. .
. ' . ' ', . .
11)61ti30
is carri~d out hx.exp~sure.'o~ th~ baker.y foods to.a controlled
amount of micro~a~.'and.infxarea pow~r for. a.preae~ermined
period of time~' It has been found ~hat satisfactory recon-
stitution will occur w~en the bakery food is exposed at an
infrared ambient temperature'in th~'range'of 200. - 500F.and
to a to~al infrarea and microwave'power density, measured in
terms o the heating of "conductivity water", in the range of
~ 0.1 - 0.92 Watts per gram for a time'suffici~nt to reconstitute
the bakery foods, which.is approximataIy 0~5 to 7 minutes.
10. The total power density to satisfactorily reconstitute'bakery
. foods is in-the range 0,25 - 2.10 Watt minutes per gram.- It is
preferred that after exposure to the microwave'and infrared
power, the bakery goods be allowed'to reach'room temperature
prior to sale, which typically takes about 10 minutes. Bakery
foods reconstituted under these conditions have been found to
exhibit the appearance, texture, chewability and u~iformity
found in freshly prepared bakery foods~
. Reconstitution o~ the bakery foods is preferably
2~. carried out in an appara~us construotea and designed to provide '
'. the power density and exposure time with a minimal amount of 1 .
skill required of the operator to ensure low cost and uniformity
of the product.
Further objects, features and advantages of the
i inven~ion will become apparent upon consideration of the
following detailed description taken in cooperation with the
' accompanying drawings, wherein:
3a
3~
~ FIG. 1 is a block diagrammatic representation of
the steps in the commercial bakery system from an ini-tial
production of the bakery foods in the central bakery through
freezing, storage transpor-tation to a retail sales outlet and
reconstitution of the bakery foods for sale to the public;
FIG. 2 is a graph of time versus power density
in watts per gram which shows the ranges for the variables for
reconstituting frozen baker~ foods;
FI~. 3 is a side elevation view with parts broken
away and in section illustrating an apparatus for carrying out
the reconstitution feature of the invention;
FIG. 4 is a front elevation and sectional view taken
along the line 4-4 of FIG. 3 with parts broken away illustrating
the reconstitution apparatus of the invention.
Referring to FIG. 1, there is shown a diagrammatic
representation of a commercial bakery system in which large
quantities of bakery foods are prepared in a regional bakery 10,
frozen and transferred to retail outlets 30, where the frozen
~bakery foads are reconstituted for sale. The invention in some
of its detailed aspects is illustrated as related to production
of doughnuts; however, it will be appreciated by those skilled
in the art that the details of the system will be readily adapt-
able to other bakery foo~s.
The first step in the regional bakery, as represented
by block 12, is the production of fresh bakery foods. This step
--6--
.. ...
', . ': .'' , .
3C~
may be carried out in many conventional ways; however an
automated process is preferred. In a typical automated
production process for producing yeast-raised doughnuts, a
dough extruding and cutting device deposits successive rows
of doughnuts onto an endless conveyor belt which transports
the dough into a dough-proofing machine. From the proofing
machine, the dough is transported to a continuous deep
frying unit. Details o this system for the production of
doughnuts can be obtained by reference to U.S. Patent No.
3,699,899 issued to Schiffman-et al on October 24, 1972.
Once the doughnuts have been prepared, they are glazed,
iced or filled as required, cooled and conveyed to a blast
freezer where they are quickly frozen, block 14. The icings ;~
and glazes used are typical of those required for high
stability wholesale moistureproof, packaged bakery productsr
Following freezing, the doughnuts are transferred to trays,
block 16 which have been coated with a fat-resistant mater-
ial, such as Daran. Typically, the trays are made of
corrugated high heat-resistant paper which is transparent
to microwaves,weigh about 170 grams and are approximately
11 inches by 23 inches by 2 inches with a one-half inch
inward flute. The trays are overwrapped, block 1~, with a
moistureproof material, such as 0.02 mil low density polye-
thylene. The individual trays are then stored in groups,
block 20, for example, by placing the individual trays in
; corrugated cases, and placing the cases on pallets in a
freezer at about 0F. The production of other
! ~
. .
~ 6~ 3~
bakery foods is within the skill of workers in the ar-t and
need not be discussed in detail herein.
On order from retail sales outlets, the frozen bakery
foods are transferred, block 22, typically by tractor-trailer
having appropriate provisions for maintaining low temperature
sufficient to keep the doughnuts froze~, to the retail sales
outlet, typified by block 30. ~t the retail outlet, the dough-
nuts are transferred from the tractor-trailer to a freezer,
block 32, typically maintaining a temperature of 0F to ~10F
for storageO When reconstitution is desired, a tray of doughnuts
is selected, block 34, the overwrapped material is removed,
block 36, and the doughnuts are reconstituted under controlled
conditions of ambient temperature, microwave power density and
time, block 38, as will be explained in greater detail below.
After reconstitution, the doughnuts are equilibrated to room
temperature for ten minutes and transferred to a counter where
they are available for customer purchase, as represented by
blocks 40, ~2. This typical commercial bakery system provides
an efficient and low cost operation for providing doughnuts and
other bakery foods from a central bakery to retail sales outlets
for distribution to the general public. The high quality bakery
foods thus produced can be provided to the public without the
necessity of expensive and complex machinery at each retail
store or the need for highly skilled personnel at the retail level.
Having described the overall commercial bakery system,
what will now be described is the process for reconstituting
. .
3a
bakery foods. It has been found that there exists a range of
combined microwave and infrared power and exposure time to
which the bakery foods can be exposed in order to insure that
the reconstituted bakery foods have ~he same quality and
characteristics as freshly prepared bakery foods.
The power required for proper reconstitution is
preferably expressed in terms of power densities, measured in
watts per gram or energy density, measured in watt minutes per
gram. It is advantageous to discuss power density in terms of
the power required to heat a volume or unit weight of "conduc-
tivity water" (that is, water which either through special
distillation procedures, or ion-exchange resin techniques,
has been reduced in ion content to a specific conductance on
the order of 1 x 10 6 ohms~l cm 1 or less). Since such water
is a standard material, its dielectric properties are well
known. Reference may be made to "Dielectric Materials and
Applications" by A. R. von Hippel, MIT Press, 1954, which lists
the dielectric constant and loss tangent for conductivity water
over a wide range of frequencies and temperatures. Once the
power density required to heat the standard material is known,
it is possible for one skilled in the art to determine the field
strength required in the microwave oven to provide the necessary
power density at any frequency by employing the following
relationship:
. , ,. , ,........... , :
, ~- .. . .
... . .. ..
,,,, ' ,. . '~ ' ',' , ' ', '
~61~3~
P/V = E2K (tanS) 2~fco
where:
P = power generated in conductivity water
V = volume of conductivity water
E = field strength
K = relative dielectric;constant
of conductivity water
tan ~ = loss tangent of conductivity water
f = frequency of the high-frequency generator
cO= dielectric constant of air fio 9 faradsl
~361r meter /
The power density in a particular microwave cavity
can also be obtained experimentally as follows: a pyrex dish
filled with 1000 ml of conductivity water at 68F is exposed
to microwave energy in the microwave cavity for 60 seconds.
The water temperature is then read. It is known that for a
microwave generator output power of lKW and 100% efficiency,
the rise in water temperature would be 26F. The microwave
power in watts can be computed by dividing the total temperature
rise by 26, multiplying by 1000 and multiplying the result by
Z0 the ratio of the microwave generator output power to one kilo-
watt. Similarly, the power produced by the infrared ambient
can be similarly determined by measuring the temperature rise
in water produced by exposure to the infrared. The total power
contributed by the microwave and infrared ambient is then com-
puted as the sum of the energy supplied by the individual sources.
-10-
: .. .. ... . .
Lt;3(1
After extenslve investigation, it has been found
that frozen bakery foods can be reconstituted in a microwave
cavity when exposed to combined microwave and inf~ared power
- density between 0.1 and 0.92 watts per gram; and preferably in
the range of 0.2-0.63 watts per gram. With power density
below 0.1 watts per gram or above 0.92 watts per gram un-
satisfactory results can occur. Below 0.1 per gram, reconsti-
tution is relatively slow. Power density exceeding 0.92 watts
per gram, can result in burning, excessive moisture loss, hot
spots, runaway and melted icing and the product
is subject to collapse.
Another variable found important in the reconstituting
of bakery foods is the temperature of the infrared ambient.
Infrared is necessary to properly rèconstitute the icings and
glazes on the frozen bakery foods and to provide the proper crust
texture and appearance. A temperature ~ange of 200-300F has
been found to provide the best results, although 200-500F may
be used.
A third variable is the time that the bakery foods
are exposed to the microwave and infrared conditions. The pre-
ferable range of exposure time is less than four minutes.
Four minutes represents a practical upper time limit because of
reconstitution machine size and capacity. Exposure times of
from 30 seconds to 7 minutes may provide satisfactory reconsti-
tution.
., . . . - , ,
., .. , . . . . ,~.
,. . . . , .:
3(~
It has also been found that the relationship of the
total power, product weight and exposure time can be advantage-
- ously expressed in terms of energy density, measured in wa-tt
minutes per gram. Expressed in terms o~ energy density, re-
constitution is carried out in the range of 0.25-2.10.watt minutes
per gram and preferably within the range of 0.70-1.55 watt minutes
pe.r gr~lm. Frozen bakery foods reconstituted in a microwave
cavity in accordance with this invention exhibit all the
characteristics of freshly prepared foods.including appearance,
texture of crumb, icings and glazes, moisture content, taste
and shelf life~
Referring now to FIG. 2, there is shown a graph of
time (in minutes) versus power density (in watts/gram) which
. is useful in understanding the invention. As shown in FIG. 2,
there is a preferred range of power density~and time in which
the reconstituted bakery foods exhibit excellent product char-
acteristics similar`to freshly prepared bakery foods.. In the
upper and lower transition ranges, shown in FIG. 2, excellent
reconstitution may also occur; however, in these ranges there
may be occurrences of non-uniform results and possibly unsatis-:
factory products. Above the upper transition range, the bakery
foods have been found to be unsatisfactory, generally being
too hot, probably because of runaway effect. Below the
lower transition range, the bakery foods are generally unsatis-
factory, being too cold or frozen after the reconstitution
process.
-12- .
.
6~ ~ 3a~
A further understanding of the invention can be
obtained from Table I, which shows the results of
reconstitution of various bakery~foods. The table is divided
into columns, which are headed by the variable parameters used,
and rows for the various balcery foods which were reconstituted.
Column (I) lists,the type of product tested which includes:
various types of doughnuts; such as Iced Bismarks~ Iced Stick~
other bakery foods,
Chocolate Iced Stick and Glazed Ring, and~ such as Coffee Cake,
Danish Streusel, and Iced Pecan Coffee Cake and Layer Cake,
Apple Fruit Danish and Cherry Fruit Danish, Soft Rolls, Honey ..
Buns~ and Honey Pull Aparts. Column (II) lists the ambient
in~rared temperature of the microwave cavity. Columns (III~, (IV~
and (V) list the microwave, infrared and total power, respectively.
Column (VI) lists the total weight, in grams, of the tray of
products which was reconstituted. Column (VII) lists the total
e~posure time. Column (VIII) and (IX) list the total energy and
power densities, respectively and Column (X) lists the average
temperature of the bakery foods on the tray after reconstitution.
T~e average temperature of the bakery foods after reconstitution
should be in the range of 60F-90F. While bakery foods outside
this range may be satisfactory, it has been found that bakery
-foods with an average temperature above 90 may be too hot and
subject to turning stale, while bakery foods with an average
temperature below 60F may be too cold for commercial sale.
Reconstitution of the bakery foods listed in Table I
was carried out by placing a tray having a number of individual
bakery foods set forth in Column ~I), and having a total weight
. . .
-13-
- ' ~ ' ' , ' . ~ ', " ' ........ . .
~ 6~ ~ 3~
set forth in Column (VI) in a microwave cavity with an infrared
ambient temperature set forth in Col~n (II) and subjecting the
bakery food to a combined infrared and m;crowave power, as set
forth in Columns (III), (IV) and (V) for an exposure time as
set forth in Column (VII). The total energy density (Column
(VIII) ) is determined by mul;tiplying the total energy
(Column (V) ) by the exposure time (Column (VII) ) and dividing
the result by the product weight (Column (VI) ~. The power
density (Column (X) ) is obtained by dividing the total power
(Column (VI) ) by the product weight (Column (VI) ). After
reconstitution the temperature of each bakery food in the
tray is measured by known techniques and the average temperature
is set forth in Column (X).
Finally each bakery food wa.s examined after recon-
stitution to determine whether its characteristics such as taste,
appearance and moisture were similar to freshly prepared bakery foods
and the comments listed in Column (XI). The comments indicate
that certain products were excellent with good icing; that
is, the reconstituted bakery food was similar to a freshly
prepared bakery food. A good product is a reconstituted bakery foods
which had characteristics similar to the freshly prepared bakery foods
but had certain noted deficiencies, such as hot spots, slight
melting of the icing or being too hot or too cold. Other bakery
foods were unsatisfactory as noted.
-14-
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--18
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F ~i
The bakery foods are preferably reconstituted in
an apparatus designed for this purpose. While there are many
different and various types of apparatus that coulcl be used~
reference is now made to FIGS. 3 and 4, wherein there is shown
a microwave system.usef~ll in carrying out this invention~ and
gcn~rally designated by refe~ence numeral 50, which includes a
combined microwave~infrared oven 52 defining a housing or closure
54 providing a microwave c;-vity C which is mounted on a frame 56.
Provision is made for an appropriate microwave generator (not
.10 . shown) via an appropriate coupling, for introducing microwave
. energy into cavity C. A typical microwave generator is a
Phillips Magnetron Model Y1490~91*rated at 1.2 KW with a fre-
quency of 2450 M~lz, Also in cavity C are suitable upper :
and lower heating elements 72 which may be
of the infrared type as is well known in the art~ The cavity
.also contains mode stirrers 73 for providing uniform distribution
of microwave power, as is known in ~he art. .-
- The housing 54 may be fabricated in any convenient
fashion in accordance with techniques generally understood for ..
establishing microwave cavities, with the housing 54 including
bottom wall 58, top wall 60, and leading and trailing end walls.
: 62, 64. Projecting outwardly from leading end wall 62 of
houslng 54 is conveyor supporting extension 66. Further, ~here
is provided a movable entry gate trap 68 which operates between
an upper and lower position to open and close port 70 which
serves as a combined entry and exit port for the bakery foods.
*Trademark
- , -19-
_......... .. ,~ - ' l ' ' " '~
~0~ 6 3(~
Trap 68 in conjunction with a microwave cavity choke system
serves to reduce and substantially eliminate the leakage o~
microwave energy from cavity C. E~tension 66 cooperates with
the lower edge of port 70 to establish a horizontal supporting
plane above whic~l a conveyor ~elt 74 .passes. The frozen bakery
food 76 to be reconstituted in the combined microwave-infrared
oven 52 has preferably been previously stored on tray 78 which
is manually loaded onto conveyor belt 74 external to the com- -
bined entry and exit port 70 in advance of movable gate trap 68
such that bakery food 76 may pass below movable trap 68 (when
it is in its upper position) through combined entry and exit
port 70 and into cavity C. In the cavity, the bakery food is
exposed to the controlled amount of power for a specific time, .
as explained in detail above, after which conveyor belt 74 is
reversed and the bakery food 76 is withdrawn over the same path
and tray 78 and the reconsti.tuted bakery food are manually ~ .
unloaded from belt 74.
Turning now to the constructional details of the
conveyor and drive system, as is shown in FIGS. 3 and 4, con- . .
~eyor belt 74 is preferably made up of a material such as plastic
or fabric and is mounted to be rotatable over suitable belt
rollers 80 and belt drive roller 82. A conveyor drive motor
M-2 and drive sprocket 84 is connected by an appropriate drive
belt 86 to drive sprocket 88 connected to drive roller 82.
In addition, drive sprocket 84 is provided with a limit switch ..
actuating projection 90 for actuating limit switches LS A and
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LS-B which are appropriately mounted 180-apart on frame 56.
The conveyor drive system is arranged so that a 180 rotation
of drive;sprocket 84 moves~h~e-bakery -fo~d~from its loading and
unloading position outside microwave cavity C (shown in solid
lines) to its exposure position inside microwave cavity C
taS shown in dotted lines).
In operation, when motor M-2 actuates conveyor 74 to
transport bakery foods into cavity C, drive sprocket 84 rotates
180 until projection 90 depresses limit switch LS-B, which
removes power from motor M 2. When the exposed bakery food is
withdrawn from cavity C, the direction of rotation of motor M-2
is reversed, drive sprocket 84 rotates in the opposite direction
until projection 90 contacts switch LS-A which deactivates motor
M-2 with the bakery food positioned at the combined loading and
unloading station.
The microwave system is also provided with a movable
gate trap 68 mounted ~o be movable relative to microwave-infrared
oven cavity 52 between a lower position in which the combined
entry and exit port 70 is closed and an upper position in which
port 70 is open so that food product 76 may pass into and out
of microwave cavity C on conveyor belt 74. More particularly,
movable gate trap 68 includes two vertical side members 100, 102
joined by a horizontal member 104 extending between vertical side
members 190, 102. Vertical side members 100, 102 having hori-
zontal projections lOOa and 102a for the purpose to be explained.
In addition, springs 106, 108 are connected to vertical 6ide
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members lO0, 102 and cooperate to move gate trap 68 between its
upper and lower positions.
The gate trap actuating system also includes a drive :
motor M-l having an eccentrically mounted disc 110 coupled to
the motor by shaft 112. Mount.ed t.o.horizontal cross-bar 104 is
a disc follower 114. Mounted on frame 56 are two pairs of limit
switches, LS-l, LS-2, which are positioned for engagement by
projections lOOa and 102a, as the gate trap is raised or lowered
as will be explained.
1:0 With gate trap 68 in raised position, activation of
motor M-2 will produce rotation of eccentric disc llO which is .:
followed by disc follower 112 on horizontal bar 104, thereby
closing gate trap 68. Springs 106, 108 aid in maintaining con-
tact between the eccentric disc and follower and urge the gate
trap downward. Motor M-2 operates until projections lOOa, 102a
engage limit switches LS-2 which upon being depressed deactuates ..
motor M-l and provides a safety interlock to prevent microwave
radiation from being transmitted into cavity C until the gate
trap is fully closed.
As most clearly shown in FIG. 4, the microwave-infrared
oven also includes a control panel 120 positioned centrally above
the gate trap which provides the controls for operating the oven.
The panel preferably has a panel cover 122 which may be closed to
prevent tampering with the settings for controlling the microwave .
oven. The control panel includes a thermostat, 124, which is used
to set the infrared temperature in the cavityO A thermocouple
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~ 6~L630
(not shown3 is positioned to insure uniform infrared heating
and an indicator lamp 128 provides an indication that infrared
energy is being supplied to the ca~i~y as is known. The control
panel also includes a timer 126 for setting the total exposure
time of microwave and infrared erlergy which controls the re-
constitution of the bakery food.
The right side of the panel has two stitches 130, 132
which are used to select a predetermined microwave energy level,
as will be explained below. Of course, the apparatus could be
provided with other adjustments for microwave energy, or the
microwave energy could be continuously adjustable Switch SW-l
is an on/off switch for operati~g the oven and switch 134 is a
service switch which is used to raise the gate trap for servicing
and cleaning when appropriate.
A typical sequence of operation for reconstituting
a typical bakery food is as follows:
The infrared ambient temperature is selected by setting
thermostat 124 for the appropriate temperature and the exposure
time selected by setting timer 126. In one commercial bakery
system it is contemplated that the bakery foods will be provided
in trays wherein the total weight of the bakery food to be re-
constituted is either 900-1200 grams or 1500-1~00 grams.
Therefore, in the illustrated apparatus one of two preset micro-
wave power levels, 350 or 550 watts, can be selected by switches
130 or 132 respectively in combination with the proper ambient
temperature and exposure time settings. Of course, other micro-
wave power selections can be readily provided. Frozen bakery
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products are loaded onto conveyor 74 and starting switch SW
is depressed.
Alth~ugh the gate trap is shown in the raised position
Eor illustrating the apparatus, it is preferred that when the
apparatus is not in use, the gate trap be~in ~he lowered position
so as to maintain the microwave cavity ~t a raised ambient tem-
perature thereby conserving power. There~ore the following
sequence of operation will be explained with the assumption
that the gate trap is in the lower position at the start of the
operation.
When starting switch SWl is depressed, motor M-l
is actuated to open the gate trap. When the gate trap is fully
opened, projections lOOa, 102a contact and close switch LS-l which
in turn actuates the motor M-2 to move the conveyor with the
bakery food into the oven. Switch LS-B is depressed by pro-
jection 90 when the bakery food is in place, which in turn ac-
tuates motor M-l to lower the gate trap. With the gate trap again
fully lowered, switch LS-2 is depressed by projections lOOa, 102a
thereby activating the timer and permitti~g microwave power to be
~ransmitted into the cavity.
The bakery foods are now exposed to a controlled total
combined microwave and infrared power which reconstitutes the
bakery foods in a minimum amount o~ time.
At the end of the preset time interval~ motor M-l is
again activated to raise gate trap 68. When fully raised,
switch LS-l is again depressed, actuating motor M-2 to transport
the reconstituted bakery food from the cavity back to the combined
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loading and unloading s-~ation. Motor M-2 is~stopped when switch
LS-A is depressed by projection 90 which again activates motor
M-l to lower the gate trap. MQtor M-2 stops when switch LS-2 is
depressed by the projection on the gate trap frame The apparatus
is now ready to receive the next load of bakery foods.
Although the invention has been described with refer-
ence to particular embodimen~s, it is to be understood that these
embodiments are merely illustrative of the principals and appli-
cation of the invention. For example, a wide range of combined
infrared and microwave power exposure times and bakery food
weight can be provided to reconstitute a wide variety of
bakery foods. In addition, various apparatus can be utilized
to provide the proper power level for reconstitution. Thus, it
is to be understood that numerous modifications may be made in
the illustrative embodiments and example of the invention and
other arrangements may be devised without the parting from the
spirit and scope of the invention~
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