U.S. patent application number 12/013337 was filed with the patent office on 2009-07-16 for process for producing precooked bacon slices.
Invention is credited to DAVID HOWARD.
Application Number | 20090181138 12/013337 |
Document ID | / |
Family ID | 40850854 |
Filed Date | 2009-07-16 |
United States Patent
Application |
20090181138 |
Kind Code |
A1 |
HOWARD; DAVID |
July 16, 2009 |
PROCESS FOR PRODUCING PRECOOKED BACON SLICES
Abstract
A process for producing precooked bacon slices comprising the
steps of (a) conveying bacon slices through a spiral oven, (b)
indirectly cooking the bacon slices in the spiral oven using a
cooking medium which is circulated within the oven at a low rate
sufficient to prevent the bacon slices from being displaced on the
conveyor, and (c) adding steam to the cooking medium as necessary
to at least reduce the percentage or substantially eliminate the
presence of air in the cooking medium.
Inventors: |
HOWARD; DAVID; (Kellyville,
OK) |
Correspondence
Address: |
FELLERS SNIDER BLANKENSHIP;BAILEY & TIPPENS
THE KENNEDY BUILDING, 321 SOUTH BOSTON SUITE 800
TULSA
OK
74103-3318
US
|
Family ID: |
40850854 |
Appl. No.: |
12/013337 |
Filed: |
January 11, 2008 |
Current U.S.
Class: |
426/233 ;
426/510 |
Current CPC
Class: |
A23L 5/15 20160801; A62C
3/006 20130101; A23L 13/00 20160801; A21B 1/00 20130101; A23L 5/13
20160801; B65G 27/02 20130101; A23V 2002/00 20130101; F27D 11/00
20130101; A47J 27/16 20130101 |
Class at
Publication: |
426/233 ;
426/510 |
International
Class: |
A23L 1/01 20060101
A23L001/01; A23L 1/31 20060101 A23L001/31 |
Claims
1. A process for continuously cooking bacon comprising the steps
of: (a) placing bacon slices on a conveyor of a spiral oven such
that said conveyor carries said bacon slices through said spiral
oven in a spiral pattern, said spiral oven having at least one
opening which is open to atmospheric conditions outside of said
spiral oven; (b) indirectly cooking said bacon slices in said
spiral oven by contacting said bacon slices with a cooking medium
circulating in said spiral oven at an average contacting
temperature of at least 325.degree. F. and at a contacting flow
velocity which is sufficiently low that said bacon slices will not
be displaced on said conveyor when contacted by said cooking
medium; and (c) adding steam to said cooking medium in a manner
effective to maintain said cooking medium during step (b) such that
a partial pressure of air which would otherwise be present in said
cooking medium without adding said steam in step (c) is reduced by
at least 10%.
2. The process of claim 1 wherein, when initially contacted by said
cooking medium in said spiral oven, said bacon slices have a
surface temperature which is sufficiently low to cause an amount of
water from said cooking medium to initially condense on said bacon
slices, said amount of water being effective to prevent burning and
to promote browning of at least an edge portion of each of said
bacon slices.
3. The process of claim 2 wherein, when initially contacted by said
cooking medium, said surface temperature of said bacon slices is in
the range of from about -6.degree. to about 5.degree. C.
4. The process of claim 1 wherein said conveyor is an open conveyor
which continuously carries said bacon slices upwardly in said
spiral pattern through said spiral oven such that fat dripping from
those of said bacon slices traveling at higher elevations within
said spiral oven will fall onto those of said bacon slices
traveling at lower elevations within said spiral oven.
5. The process of claim 1 wherein said average contacting
temperature is at least 375.degree. F. and said steam is added in
step (c) in a manner effective to maintain said cooking medium
during step (b) such that said partial pressure of air which would
otherwise be present in said cooking medium without adding said
steam in step (c) is reduced by at least 20%.
6. The process of claim 5 wherein said steam is added in step (c)
in a manner effective to maintain a positive pressure condition in
said oven during step (b).
7. The process of claim 1 wherein said steam added in step (c) is
superheated steam.
8. The process of claim 1 wherein said spiral oven has choked inlet
and outlet openings for said conveyor which have a height extending
not more than 10 mm above said conveyor.
9. The process of claim 1 wherein said contacting flow velocity at
which said bacon slices are contacted by said cooking medium in
step (b) is not greater than 20 feet per second.
10. The process of claim 1 wherein said contacting flow velocity at
which said bacon slices are contacted by said cooking medium in
step (b) is not greater than 10 feet per second.
11. The process of claim 1 wherein said steam is added in step (c)
in a manner effective to maintain said cooking medium during step
(b) such that said partial pressure of air which would otherwise be
present in said cooking medium without adding said steam in step
(c) is reduced by at least 30%.
12. The process of claim 1 wherein said cooking medium is
maintained at said average contacting temperature by circulating
said cooking medium over a plurality of finned electrical heating
elements.
13. The process of claim 1 further comprising the step, prior to
indirectly cooking said bacon slices in said spiral oven, of
contacting said bacon slices with superheated steam.
14. A process for continuously cooking bacon comprising the steps
of: (a) placing bacon slices on a conveyor of a spiral oven such
that said conveyor carries said bacon slices upwardly in said
spiral oven in a spiral pattern, said spiral oven having an inlet
opening and an outlet opening for said conveyor wherein said inlet
opening and said outlet opening are open to atmospheric conditions
outside of said spiral oven; (b) indirectly cooking said bacon
slices in said spiral oven by contacting said bacon slices for a
time in the range of from about 3 to about 9 minutes with a cooking
medium circulating in said spiral oven at an average contacting
temperature in the range of from about 325.degree. to about
650.degree. F. and at a nonimpinging contacting flow velocity which
is sufficiently low that said bacon slices will not be displaced on
said conveyor when contacted by said cooking medium; and (c) adding
steam to said cooking medium in a manner effective to maintain said
cooking medium during step (b) such that a partial pressure of air
which would otherwise be present in said cooking medium without
adding said steam in step (c) is reduced by at least 15%, wherein,
when initially contracted by said cooking medium in said spiral
oven, said bacon slices have a surface temperature which is
sufficiently low to cause an amount of water from said cooking
medium to initially condense on said bacon slices and wherein said
conveyor is an open conveyor such that fat dripping from those of
said bacon slices traveling at higher elevations within said spiral
oven will fall onto those of said bacon slices traveling at lower
elevations within said spiral oven.
15. The process of claim 14 wherein, when initially contacted by
said cooking medium, said surface temperature of said bacon slices
is in the range of from about -6.degree. to about 5.degree. C.
16. The process of claim 14 wherein said steam is added in step (c)
in a manner effective to maintain said cooking medium during step
(b) such that said partial pressure of air which would otherwise be
present in said cooking medium without adding said steam in step
(c) is reduced by at least 80%.
17. The process of claim 14 wherein said steam added in step (c) is
superheated steam.
18. A process for continuously cooking bacon comprising the steps
of: (a) placing bacon slices on a conveyor of a spiral oven such
that said conveyor carries said bacon slices upwardly in said
spiral oven in a spiral pattern; (b) indirectly cooking said bacon
slices in said spiral oven by contacting said bacon slices with a
cooking medium circulating in said spiral oven at an average
contacting temperature of at least 325.degree. F. and at a
contacting flow velocity which is sufficiently low that said bacon
slices will not be displaced on said conveyor when contacted by
said cooking medium; (c) monitoring said cooking medium during step
(b) using an analyzer of a type used for determining a relative
humidity or dew point of air and for providing analyzer result
readings on a relative humidity percentage scale or other
corresponding result scale; and (d) adding steam to said cooking
medium in a manner effective to cause an analyzer result reading of
or corresponding to a value of at least 10% on a relative humidity
percentage scale to be maintained for said cooking medium during
step (b).
19. The process of claim 18 wherein said steam is added in step (b)
in a manner effective to cause an analyzer result reading of or
corresponding to a value of at least 15% on said relative humidity
percentage scale to be maintained for said cooking medium during
step (b).
20. The process of claim 18 wherein said steam is added in step (b)
in a manner effective to cause an analyzer result reading of or
corresponding to a value of at least 20% on said relative humidity
percentage scale to be maintained for said cooking medium during
step (b).
21. The process of claim 19 wherein, when initially contacted by
said cooking medium in said spiral oven, said bacon slices have a
surface temperature which is sufficiently low to cause an amount of
water from said cooking medium to initially condense on said bacon
slices, said amount of water being effective to prevent burning and
to promote browning of at least an edge portion of each of said
bacon slices.
22. The process of claim 19 wherein said conveyor is an open
conveyor such that fat dripping from those of said bacon slices
traveling at higher elevations within said spiral oven will fall
onto those of said bacon slices traveling at lower elevations
within said spiral oven.
23. The process of claim 18 wherein said average contacting
temperature is at least 375.degree. F. and said steam is added in
step (d) in a manner effective to cause an analyzer result reading
of or corresponding to a value in the range of from about 15% to
about 45% on said relative humidity percentage scale to be
maintained for said cooking medium during step (b).
24. The process of claim 18 wherein said average contacting
temperature is in the range of from about 385.degree. F. to about
550.degree. F. and said steam is added in step (d) in a manner
effective to cause an analyzer result reading of or corresponding
to a value in the range of from about 20% to about 35% on said
relative humidity percentage scale to be maintained for said
cooking medium during step (b).
25. The process of claim 18 wherein said average contacting
temperature is in the range of from about 325.degree. F. to about
385.degree. F. and said steam is added in step (d) in a manner
effective to cause an analyzer result reading of or corresponding
to a value in the range of from about 45% to about 85% on said
relative humidity percentage scale to be maintained for said
cooking medium during step (b).
Description
FIELD OF THE INVENTION
[0001] The present invention relates to processes for continuously
cooking bacon slices to produce precooked bacon strips and other
precooked sliced bacon products.
BACKGROUND OF THE INVENTION
[0002] Because of their thinness, the short cooking time required,
and the high fat and water content of the raw product, bacon slices
are among the most difficult products to cook consistently. The
continuous bacon cooking processes heretofore used in the industry
have not been able to provide precooked sliced bacon products
having the same texture, bite, mouth feel, color, and appearance as
pan-fried products cooked in the home. Thus, a need presently
exists for a significantly improved continuous process and system
capable of producing such precooked sliced bacon products. A need
particularly exists for a process of this type which (a) will
provide a production rate similar to the microwave processing
systems currently used in the art, (b) will take up less floor
space in the processing facility, and (c) will eliminate or at
least greatly reduce the fire risk posed by other systems.
[0003] Heretofore, in the United States, precooked sliced bacon
products have been predominantly produced using continuous
microwave oven systems. Such microwave cooking processes have
typically involved the steps of (a) preconditioning belly,
shoulder, or back bacon or a formed bacon log to a temperature in
the range of from about -4.degree. to about 5.degree. C.; (b)
passing the preconditioned bacon through a Grote Slicer or similar
slicing device; and then (c) conveying the sliced bacon through a
continuous microwave oven. As will be understood by those in the
art, the Grote Slicer is typically positioned to place the bacon
slices directly on the oven conveyor as they are cut.
[0004] Unfortunately, the continuous microwave processes heretofore
used for producing precooked sliced bacon products have significant
shortcomings and disadvantages. For one thing, there are
significant organaleptic differences between the product produced
by a continuous microwave process versus a traditional home-fried
product. This is due in large part to the fact that the microwave
energy has a more pronounced effect on the fat and water components
of the bacon than on other parts. Thus, the microwave product has a
significantly different texture, mouth feel, bite, appearance, and
color. In addition, continuous microwave oven systems can be as
much as 70 feet or more in length and, thus, take up a great deal
of space in the processing facility.
[0005] As an alternative to continuous microwave cooking, precooked
sliced bacon products have also been produced using continuous
linear circulating air oven systems. Unfortunately, however, the
products produced in the linear circulating air oven systems have
been even less crisp and lighter in color than the microwave
products. In addition, the linear circulating air systems have had
a tendency to burn or blacken the edges of the bacon slices and
have also required an even greater amount of floor space to achieve
throughputs approaching those of the microwave systems. Further,
because of the large amount of hot, flammable grease produced when
cooking bacon, the fire risk presented by a circulating air oven is
very high.
[0006] In addition, as will also be understood by those in the art,
the general trend in the meat industry for achieving improvements
in circulating air cooking processes has been toward the use of
increasingly higher flow circulation rates and impingement
velocities. Unfortunately, however, the application of high
velocity impingement air to the rather delicate, thinly sliced
bacon product traveling through the oven causes the product to be
displaced on (i.e., to be moved on or blown off of) the oven
conveyor belt. Also, linear impingement oven systems would still
take up a relatively large amount of space in the processing
facility and would present an even greater fire risk for bacon
cooking.
SUMMARY OF THE INVENTION
[0007] The present invention provides a spiral oven process for
preparing precooked sliced bacon products which unexpectedly and
surprisingly satisfies the needs and alleviates the problems
discussed above. The inventive spiral oven process and system can
produce a precooked sliced bacon product of generally any desired
crispness and generally any desired color ranging from light gold
to very dark golden brown. The inventive system also has a very
small footprint and eliminates or at least greatly reduces the fire
risk posed by the prior art circulating air oven systems. Moreover,
the inventive bacon cooking process will produce a consistent
product which does not have burned or blackened outer edges and is
much closer than a microwaved product to home-fried bacon.
[0008] In one aspect, there is provided a process for continuously
cooking bacon comprising the steps of: (a) placing bacon slices on
a conveyor of a spiral oven such that the conveyor carries the
bacon slices through the spiral oven in a spiral pattern, the
spiral oven having at least one opening (e.g., for the conveyor)
which is open to atmospheric conditions outside of the spiral oven;
(b) indirectly cooking the bacon slices in the spiral oven by
contacting the bacon slices with a cooking medium circulating in
the spiral oven at an average contacting temperature of at least
325.degree. F. and at a contact flow velocity which is sufficiently
low that the bacon slices will not be displaced on the conveyor
when contacted by the cooking medium; and (c) adding steam to the
cooking medium in a manner effective to maintain the cooking medium
during step (b) such that a partial pressure of air which would
otherwise be present in the cooking medium without adding the steam
in step (c) is reduced by at least 10%.
[0009] In another aspect, there is provided a process for
continuously cooking bacon comprising the steps of: (a) placing
bacon slices on a conveyor of a spiral oven such that the conveyor
carries the bacon slices upwardly in the spiral oven in a spiral
pattern, the spiral oven having an inlet opening and an outlet
opening for the conveyor wherein the inlet and outlet openings are
open to atmospheric conditions outside of the spiral oven; (b)
indirectly cooking the bacon slices in the spiral oven by
contacting the bacon slices for a time in the range of from about 3
to about 9 minutes with a cooking medium circulating in the spiral
oven at an average contacting temperature in the range of from
about 325.degree. F. to about 650.degree. F. and at a nonimpinging
contacting flow velocity which is sufficiently low that the bacon
slices will not be displaced on the conveyor when contacted by the
cooking medium; and (c) adding steam to the cooking medium in a
manner effective to maintain the cooking medium during step (b)
such that a partial pressure of air which would otherwise be
present in said cooking medium without adding said steam in step
(c) is reduced by at least 15%. When initially contacted by the
cooking medium in the spiral oven, the bacon slices have a surface
temperature which is sufficiently low to cause an amount of water
from the cooking medium to initially condense on the bacon slices.
In addition, the conveyor is an open conveyor such that fat
dripping from those of the bacon slices traveling at higher
elevations within the spiral oven will fall onto and baste those of
the bacon slices traveling at lower elevations within the spiral
oven.
[0010] In another aspect, there is provided a process for
continuously cooking bacon comprising the steps of: (a) placing
bacon slices on a conveyor of a spiral oven such that the conveyor
carries said bacon slices upwardly in said spiral oven in a spiral
pattern; (b) indirectly cooking the bacon slices in the spiral oven
by contacting the bacon slices with a cooking medium circulating in
the spiral oven at an average contacting temperature of at least
325.degree. F. and at a contacting flow velocity which is
sufficiently low that the bacon slices will not be displaced on the
conveyor when contacted by the cooking medium; (c) monitoring the
cooking medium during step (b) using an analyzer of a type used for
determining a relative humidity or dew point of air and for
providing analyzer result readings on a relative humidity
percentage scale or other corresponding result scale; and (d)
adding steam to the cooking medium in a mainer effective to cause
an analyzer result reading of or corresponding to a value of at
least 10% on the relative humidity percentage scale to be
maintained for the cooking medium during step (b).
[0011] Further aspects, features, and advantages of the present
invention will be apparent to those or ordinary skill in the art
upon examining the accompanying drawings and upon reading the
following detailed description of the preferred embodiments.
BRIEF DESCRIPTION OF THE DRAWINGS
[0012] The drawing schematically illustrates an embodiment 2 of the
inventive spiral oven process for continuously cooking bacon
slices.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0013] An embodiment 2 of the inventive spiral oven process for
continuously cooking bacon slices is illustrated in the
accompanying drawing. In the inventive process 2, raw bacon slices
4 are placed on the infeed section 6 of the continuous conveyor
belt 8 of a spiral oven 10. The raw bacon slices 4 are preferably
laid directly on the conveyor infeed section 6 as they are cut from
a bacon source (e.g., belly, shoulder, or back bacon, a formed
bacon log, or other source) by a Grote Slicer or similar slicing
device.
[0014] The spiral oven 10 used in the inventive process 2
preferably comprises: an oven housing 12 having a cooking chamber
15; a plurality of heating elements 14 positioned in the upper
portion of the housing 12 above the cooking chamber 15; a plurality
of air flow cones or nozzles 16 provided in the upper portion of
the housing below the heating elements 14 for delivering the heated
cooking medium into the cooking chamber 15; a circulation fan 18
provided in the housing 12 below the heating elements 14; an
exterior fan motor 20; an upper steam injection ring 22 positioned
between the circulation fan 18 and the heating elements 14; an
optional lower steam injection ring 24 provided in the bottom of
the combustion chamber 15; a conveyor inlet opening 26 located at
an elevation near the bottom of the cooking chamber 15; a conveyor
outlet opening 28 located at an elevational near the top of the
cooking chamber 15 beneath the air flow cones or nozzles 16; and a
conveyor outlet section 30 which delivers the cooked sliced product
32 from the outlet 28 of the spiral oven 10.
[0015] As is typical in spiral ovens, the conveyor belt 8
continuously conveys the bacon slices 4 upwardly in the cooking
chamber 15 in a spiral pattern as illustrated in the drawing. The
belt 8 is preferably an open mesh belt (commercially available from
Ashworth Brothers, Cambridge international, and other
manufacturers) or other type of open belt such that, as illustrated
by basting drippage arrows 36, the fat which drips from the
products 4 traveling along the spiral flites 34 at succeedingly
higher elevations within the oven housing 12 will fall onto and
baste the bacon slices 4 traveling along the flites 34 at lower
elevations. At the same time, the cooking medium circulation fan 18
circulates the hot cooking medium within the oven housing 12 in a
flow pattern 38 such that the fan 18 draws the cooking medium
upwardly from the cooking chamber 15 and blows the cooking medium
through the upper heating elements 14 and then downwardly via the
air flow cones or nozzles 16 back into the cooking chamber 15.
[0016] The raw bacon slices 4 placed on the conveyor infeed section
6 can be of any desired type, size, thickness, or shape. The slices
4 will typically be in the form of common breakfast strips which
are approximately two inches wide, approximately 10-12 inches long,
and from about 1 to about 5 mm thick. Wider slices can be provided,
for example, by bonding two bellies together prior to slicing. The
thickness of the bacon slices 4 will typically be in the range of
from about 1.2 to about 3.5 mm and will more typically be in the
range of from about 1.6 to about 3 mm. As mentioned above, because
of their relative thinness and the short cooking time required,
bacon slices are among the most difficult products to cook
consistently.
[0017] In accordance with the inventive process 2, the bacon slices
4 are indirectly cooked as they travel upwardly through the cooking
chamber 15 of the spiral oven 10 by contacting the bacon slices
with the heated cooking medium which is circulated through the
oven. In addition, another novel and unexpectedly beneficial aspect
of the inventive bacon cooking process is that the cooking medium
will preferably be a high enthalpy, superheated vapor medium
comprised of at least a high level of water vapor.
[0018] The high water vapor content of the cooking medium within
the spiral oven 10 will preferably be produced and maintained by
injecting steam into the oven 10 as needed via the upper steam
injection ring 22. Alternatively, or in addition, steam can be
injected into the oven 10 via the steam injection ring 24 within
the bottom of the cooking chamber 15. The steam can be saturated
steam or superheated steam and will preferably be superheated steam
under pressure. The steam used in the inventive process will
preferably be superheated steam provided to the inventive cooking
system at a pressure of about 40 psig and a temperature of at least
265.degree. F.
[0019] The amount of steam used in the inventive process will be an
amount effective to reduce the partial pressure of or substantially
eliminate the air which would otherwise be present in the "natural"
cooking environment if no steam were injected into the spiral oven
10. Without steam injection, the "natural" cooking environment
would be comprised of (a) air, (b) volatile organics resulting from
the bacon cooking process, and (c) an amount of water vapor derived
from the water content of the raw bacon slices 4 and from the
atmospheric humidity of the air. As will be understood by those in
the art, some additional water content in the "natural" cooking
medium environment can also be derived from any moisture which
happens to remain on the conveyor belt 8 as a result of the
continuous external belt cleaning process used during oven
operation.
[0020] The reduction of air partial pressure and/or air content in
the otherwise natural cooking environment results from the
injection of steam and can also further result from the creation of
a positive pressure condition with the oven 10. Depending, for
example, on the size of the belt inlet and outlet openings 26 and
28 and upon the existence of any other openings, the injection of a
sufficient amount of steam into the spiral oven 10 can, and
preferably will, create a sufficient positive pressure condition in
the oven 10 to substantially prevent outside air from entering the
oven openings during operation. Moreover, the design of the spiral
oven 10 and the amount of steam injection can be sufficient to
create enough of an internal positive pressure condition to cause
some of the internal vapor to flow out of oven openings, thus
resulting in a steady state condition wherein substantially all of
the air has been removed and replaced with steam.
[0021] The amount of steam injected into the spiral oven 10 in the
inventive bacon cooking process will preferably be an amount
sufficient to reduce the partial pressure of air which would
otherwise be present in the "natural" cooking environment by at
least 10%. The amount of steam injected into the spiral oven 10
will more preferably be an amount sufficient to reduce the partial
pressure of air which would otherwise be present by at least 15%,
at least 20%, at least 30%, at least 40%, at least 50%, at least
60%, at least 70%, at least 80%, or at least 90%. The amount of
steam injected into the spiral oven 10 will most preferably be an
amount sufficient to replace substantially all of the air which
would otherwise be present in the "natural" cooking
environment.
[0022] In another surprising and unexpected aspect of the present
invention, it has been discovered that an extremely effective
method for monitoring and controlling the injection of steam into
the spiral oven 10 to target and achieve any desired sliced bacon
product characteristics is to use a Vaisala dry cup dew point
analyzer or other relative humidity and/or dew point monitoring
device. The unexpected success obtained through the use of an
instrument of this type for targeting and achieving substantially
any desired product result in the present invention is particularly
surprising in view of the fact that the concept of "relative
humidity" above the intended operational limit of such instruments
(i.e., the boiling point of water) is, at best, ambiguous. Even
more surprising is the discovery that the resulting purported
"percentage" or other equivalent readings indicated on the relative
humidity percentage scales or corresponding scales (e.g., "dew
point temperature") of such instruments can be used in the
inventive process to successfully control steam injection rates for
achieving specific product results even though, in many and perhaps
even most cases, most or all of the air in the oven 10 will
actually have been replaced with superheated steam.
[0023] The sensor for the Vaisala dry cup dew point transmitter or
other device can be placed at generally any desired location within
the spiral oven 10. Although readings can be monitored at any
desired location or at a plurality of points within the spiral oven
10, the analyzer readings for the cooking medium will preferably be
taken close to the actual cooking point, most preferably at a
midpoint elevation in the cooking chamber 15 and as close to the
product as is reasonably feasible.
[0024] When using a Vaisala dry cup analyzer or similar instrument
in the inventive process, the rate of steam addition to the spiral
oven 10 will preferably be controlled to maintain a targeted
analyzer reading in the range of from at least 10% to 100%. In most
cases, a targeted instrument reading in the range of from about 15%
to about 90%, more preferably from about 20% to about 85%, will be
used to control the rate of steam injection to obtain the
particular product characteristics desired. Once again, this
control method has been found to be very effective for use in the
inventive process even though the instrument may not actually be,
and likely is not, measuring a true "relative humidity" of the
heated cooking medium.
[0025] Depending upon the desired operating ranges (e.g., the
temperature range used and whether the environment is substantially
oxygen free or contains oxygen) and other factors, it will be
understood that oxygen analyzers or other types of instruments
could be used to monitor and maintain targeted conditions within
the spiral oven 10 in at least some cases.
[0026] In further contrast to the industry trend toward using
higher flow velocities, even in spiral ovens, the inventive process
also unexpectedly provides surprising bacon cooking benefits by
circulating the cooking medium within the spiral oven in a more
gentle, convective, nonimpinging manner such that the cooking
medium contacts the bacon slices 4 at a flow velocity which is
sufficiently low to prevent the bacon slices 4 from being displaced
on (i.e., to prevent the bacon slices 4 from being moved on or
blown off of) the conveyor belt 8.
[0027] The contacting flow velocity within different regions of the
cooking chamber 15 could vary depending upon the degree of doneness
of the product at any given point. Although some heavier raw bacon
products entering the cooking chamber 15 could be contacted at a
low flow velocity of as much as 42 feet per second without
displacing the product on the belt 8, the flow velocity, at least
in the upper region of the cooking chamber 15, will preferably be
lower in order not to displace the lighter, cooked bacon product.
Consequently, the circulation rate within at least the upper region
of the cooking chamber 15 will preferably be sufficiently low that
the cooking medium will contact the bacon slices 4 at a flow
velocity of not greater than 20 feet per second. The contacting
velocity in at least the upper portion of the cooking chamber 15
will more preferably not be greater than 10 feet per second and
will most preferably be only about 5.5 feet per second.
[0028] Spiral ovens adaptable for use in the inventive bacon
cooking process are commercially available, for example, from
Unitherm, Stein, Heat & Control, and C.F.S. The oven 10 will
most preferably be a Unitherm Electric Spiral Oven. Although such
spiral ovens are typically operated in other processes at much
higher circulation rates, the spiral oven 10 will preferably be
operated at a much lower circulation rate in the inventive process
2, as already mentioned, in order to provide a more gentle,
convective flow over the product. The fan speed of the Unitherm
Electric Spiral Oven, for example, will preferably be reduced to
provide a circulation rate of not more than 500 cubic feet per
minute (CFM) within the oven 10.
[0029] The temperature and cooking time (i.e., belt speed) within
the spiral oven 10 can be varied as desired to obtain generally any
desired degree of crispness and generally any desired color ranging
from light gold to dark golden brown. The average temperature of
the cooking medium within the cooking chamber 15 will preferably be
in the range of from about 325.degree. F. to about 650.degree. F.
or higher. Depending upon the degree of crispness and brownness
required, the residence time of the product 4 within the spiral
oven cooking chamber 15 will typically be in the range of from
about 3 to about 9 minutes.
[0030] In a preferred "high temperature" embodiment of the
inventive method, the average temperature of the cooking medium
will preferably be at least 375.degree. F. The average temperature
of the cooking medium within the cooking chamber 15 in the "high
temperature" embodiment will more preferably be controlled in the
range of from about 385.degree. to 550.degree. F. and will most
preferably be about 425.degree. F. The residence/cooking time of
the product within the spiral oven cooking chamber 15 in the "high
temperature" embodiment will preferably be in the range of from
about 3 to about 7 minutes and will most preferably be in the range
of from about 4 to about 6 minutes. In addition, if a Vaisala dry
cup analyzer or similar device is used to monitor the cooking
medium within the cooking chamber 15, the amount of steam injected
into the spiral oven 10 in the "high temperature" embodiment will
preferably be controlled to maintain an analyzer reading which is
or is equivalent to a value in the range of from about 15% to about
45%, most preferably in the range of from about 20% to about 35%,
on the purported "relative humidity" percentage scale of the
Vaisala analyzer.
[0031] In an alternative "low temperature" embodiment, the average
cooking medium temperature will preferably be in the range of from
about 325.degree. F. to about 385.degree. F. (most preferably about
350.degree. F.), the analyzer reading for the cooking medium will
preferably be maintained in the range of from about 45% to about
85% (most preferably about 75%), and the cooking time will
preferably be in the range of from about 6.5 to about 9 minutes
(most preferably about 8 minutes). The "low temperature" embodiment
eliminates smoke and provides a product with little or no pit
flavor notes.
[0032] The heating elements 14 employed in the spiral oven 10 can
be thermal oil elements, steam elements, electric elements, or any
other type of element capable of heating the circulating cooking
medium within the oven 10 to the temperature desired. Because of
the relatively high cooking temperatures typically preferred in the
inventive process 2 and in order to provide a broad range of
possible temperatures and results, the heating elements 14 will
preferably be finned electrical heating elements capable of heating
the circulating cooking medium to a cooking temperature of
650.degree. F. or higher. In addition, to ensure that a highly
consistent cooked product 32 is obtained and that none of the
cooked product 32 is either undercooked or overcooked, those in the
art will understand that the electrical heating elements 14 used in
the spiral oven 10 will preferably be tightly controlled at the
desired set point using a thyristor or similar device.
[0033] Because there is no need for the flow of makeup air into the
spiral oven 10 when employed in the inventive indirect cooking
process 2, the inlet opening 26 and the outlet opening 28 for the
conveyor 8 can each be "choked" in order to (a) minimize the energy
losses from the oven 10 to the atmosphere, (b) further stabilize
the cooking conditions therein, and (c) assist in establishing
something of a positive pressure condition in the spiral oven 10,
when desired. Each of the inlet and outlet openings 26 and 28 will
preferably be only slightly wider than the oven belt 8 and will
preferably be sufficiently limited in height to provide not more
than a 10 mm clearance, most preferably not more than a 6 mm
clearance, above the belt 8.
[0034] The high moisture content of the cooking medium, combined
with the relatively high temperature within the oven 10, the gentle
convective flow therein, and the natural basting provided by the
upward spiral path of the product through the oven 10, unexpectedly
and surprisingly provides unique benefits and advantages which have
not been provided by the circulating air systems and other systems
heretofore tried for cooking bacon slices. Even more surprisingly,
these features of the inventive process unexpectedly combine to
yield a cooked sliced bacon product 32 which has much more of a
pan-fried texture, bite, mouth feel, appearance, and color than the
previously preferred products produced using continuous microwave
systems. The high moisture, high enthalpy cooking medium employed
in the inventive spiral oven process 2 also facilitates heat
transfer into the sliced bacon product 4 and greatly reduces or
eliminates the fire risk posed by the prior circulating air cooking
systems.
[0035] Moreover, the high water vapor content used and the other
characteristics of the inventive spiral oven process 2 operate to
enhance the browning process and protect the product during cooking
so that much more of a pan-fried color and a pan-fried crispness
are obtained without burning or blackening the edges of the
product. The bacon product is preferably preconditioned prior to
delivery to the slicer such that the bacon slices 4 deposited on
the oven conveyor belt 8 will have a low surface temperature,
typically in the range of from about -6.degree. to about 5.degree.
C. Because of the low initial surface temperature of the raw bacon
slices 4 and because of the high superheated water vapor content
within the spiral oven 2, a small amount of water from the cooking
medium initially condenses on the surface of the product 4,
typically in micro droplet form, as the product enters the oven 10.
The condensate which initially forms on the product surface heats
rapidly, but it does so in conjunction with the fat on the product
surface which unexpectedly allows the fat to boil and to color the
outer edges of the product without burning. Then, combined with the
unexpected benefit provided by the initial surface condensation
effect, the fat drippage basting regime within the oven 10 from
each spiral flight 34 to the next further operates to develop the
color, crispness, and bite desired.
[0036] In addition, in an alternative embodiment of the inventive
method, the raw bacon slices 4 can optionally be pretreated prior
to entering the spiral oven cooking chamber 15 by contacting the
raw slices 4 with dry (i.e., superheated) steam. The pretreating
steam temperature will preferably be about 250.degree. F. The
optional steam pretreatment begins the moisture crusting process
and assists in producing a flatter sliced product.
EXAMPLE
[0037] A Grote Slicer is used to cut bacon slices directly onto the
conveyor infeed section 6 of a Unitherm Electric Spiral Oven 10 of
the type illustrated in the drawing. The bacon slices are each two
inches wide, 10 inches in length, and have a thickness of about 3
mm. The bacon slices have an initial surface temperature of
-6.degree. C. The belt 8 of the spiral oven 2 is an open wire mesh
belt which is 36 inches wide and which receives and conveys the raw
bacon slices in a three lane arrangement across the belt at a total
rate of 900 raw slices per minute. This is equivalent to a total
feed rate of 5400 pounds per hour of raw sliced bacon.
[0038] The oven 10 utilizes finned electrical elements 14 which are
operated to provide an average cooking medium temperature within
the cooking chamber 15 of 425.degree. F. The cooking medium within
the oven cooking chamber 15 is monitored using a Vaisala dry cup
dew point analyzer. An analyzer value of 24% for the cooking medium
is maintained by the injection of 40 psig superheated steam at
about 268.degree. F. The injection of steam produces a positive
pressure condition within the spiral oven 10 which is slightly
above atmospheric pressure. The speed of the spiral conveyor 8 is
set to provide a cooking time of 5.5 minutes. The oven fan speed is
set to provide a cooking medium circulation rate within the oven 10
of 300 cubic feet per minute.
[0039] The resulting cooked product has a crispness, appearance,
and degree of golden brown color which are substantially the same
as a bacon product which has been pan fried at 500.degree. F. for 5
minutes (i.e., 2.5 minutes per side).
[0040] Thus, the present invention is well adapted to carry out the
objectives and attain the ends and advantages mentioned above as
well as those inherent therein. While presently preferred
embodiments have been described for purposes of this disclosure,
numerous changes and modifications will be apparent to those of
ordinary skill in the art. Such changes and modifications are
encompassed within this invention as defined by the claims.
* * * * *