Apparatus and system for conditioning food products

Apparatus for high speed grilling and/or conditioning of a food product which comprises: a heatable surface which is capable caramelizing the food product at a temperature in the range between about 425.degree. F. to 575.degree. F.; a chamber for enclosing the food product on the heatable surface under pressure; and a steam injector for introducing steam into the chamber during the caramelization of the food product.

This invention relates to the conditioning of food products. More 
particularly, the invention is directed to apparatus, system and method by 
which food products, e.g., buns, breads, muffins, etc., may be conditioned 
(i.e., caramelized and moisturized). The food product conditioning device 
of the present invention may be run either in a batch mode or an automatic 
continuous mode. 
BACKGROUND OF THE INVENTION 
Contact cooking, often referred to as "toasting" or "grilling", of food 
products such as dough products, for example breads, rolls, bagels, 
muffins and buns (hereafter collectively referred to as "buns"), is known 
in the commercial food service industry. It usually involves compressing 
one or both pieces of a sliced bun, cut-surface(s) down in contact with a 
surface heated at a high temperature for a time sufficient to heat the 
interior of the bun to from about 150.degree. F. to about 170.degree. F. 
This is done to dry and caramelize the cut surface(s) of the bun. 
Caramelization is desired because it provides a visually appealing, at 
least partially-bonded surface texture which crunches when bitten. The 
bonded surface also seals the cut surface which prevents juices from the 
food and moisture from condiments from entering the interior of the bun 
and rendering it soggy. 
Typical buns are flash frozen after the initial baking thereof. Prior to 
commercial use, the buns are thawed for a minimum of twelve (12) hours to 
room ambient temperature. This product is defined as one of the driest and 
most difficult to grill and maintain the desired final attributes. 
Conventional grilling apparatus and methods have several shortcomings. They 
are slow in that they require a grilling time of from about 30 to 45 
seconds or more to obtain the desired bun internal temperature and to 
achieve the desired caramelized contact surface texture. Also, heating the 
buns at required temperatures of about 150.degree. F. to 170.degree. F. 
for such times drives moisture out of and dries the buns. For example, 
with conventional grilling systems there is about a 5 to 7% loss of 
moisture from standard burger buns which typically have a relatively low 
moisture content of about 32%. This causes drying especially of edges of 
the buns which causes the edges to curl or roll upwards. Further, 
conventional grilling apparatus are open at both ends to allow the buns to 
enter and exit the apparatus. This is disadvantageous because it allows 
energy and heat to escape from the grilling apparatus. Conventional 
grilling systems also are not adapted to apply uniform pressure onto the 
buns to achieve uniform caramelization of buns of different or irregular 
sizes, profiles and/or configurations. 
It is a main objective of this invention to overcome the above and other 
limitations and disadvantages of conventional high temperature contact 
toasting or grilling devices. That is, the bun conditioning apparatus of 
the present invention provided improved productivity by reducing 
processing time and provides a means which contact caramelizes a bun and 
heats it 165.degree. F..+-.5.degree. F. in less than 20 seconds. 
An object of this invention is to provide an improved high temperature 
toasting or grilling apparatus and method which caramelizes buns more 
rapidly, preferably with less drying of the buns, thereby eliminating 
dried and/or rolled bun edges. 
Another object of this invention is to provide an improved high 
temperature, high speed bun grilling apparatus and method which provides 
grilled and/or caramelized buns which retain a higher percentage of their 
pre-grilled moisture content. Another object of this invention is to 
provide the aforementioned grilling apparatus which is adapted to reduce 
energy and heat loss from the grilling system. 
Another object is to provide a unique grilling apparatus which is capable 
of producing a uniform caramelization of the cut surface(s) of buns, while 
avoiding damage to or disfigurement of the buns. 
Another object of this invention is to provide a grilling apparatus which 
is capable of producing a uniform pressurization and caramelization of 
buns of different or irregular sizes, profiles and/or configurations. 
Yet another object of this invention is to provide the aforementioned 
uniform pressurization and caramelization without leaving compression 
markings on the crown of the treated buns. 
Still another object of this invention is to provide an improved high 
temperature, high speed grilling apparatus, including automated types, for 
the fast food service industry. It is also an object of the present 
invention to restore or recondition a previously flash frozen bun which 
has been thawed so as to provide an extremely dried buns. Such dried buns 
are extremely undesirable to taste and it would be highly desirable to 
restored the original soft, moist texture to a thawed bun which is 
perceived by the consumer to have the original consistency and taste of a 
fresh baked bun. 
SUMMARY OF THE INVENTION 
A method for caramelizing a surface of at least one food product which 
comprises heating a surface of the food product, in the presence of steam, 
for 20 seconds or less, preferably between about 8 to 12 seconds, and at a 
temperature and pressure sufficient to caramelize the surface of the food 
product. The method preferably comprises the additional step of applying 
pressure to the food product during the heating step. 
The food product is preferably heated to a temperature in the range from 
between about 425.degree. F. to 575.degree. F., more preferably between 
about 450.degree. F. to 550.degree. F., and most preferably between about 
475.degree. F. to 525.degree. F. 
The resultant caramelized food product exhibits a moisture loss of about 3% 
or less during the heating step, more preferably between about 1/2% to 1%. 
The pressure is developed by flashing water to produce the steam. The water 
is preferably present in an amount between about 1.5 grams to 5.5 grams 
per single food product. 
The present invention also includes a method for conditioning of food 
products which comprises the following steps: heating a heat transfer 
surface to a temperature between about 425.degree. F. to about 575.degree. 
F.; placing at least one food product against the heated surface; 
enclosing the food product in chamber formed in part by the heated 
surface; and caramelizing the food product on the heat transfer surface 
under pressure and in the presence of steam for about 20 seconds or less. 
The present invention also includes an apparatus for high speed grilling 
and/or conditioning of a food product which comprises: a heatable surface 
which is capable caramelizing the food product at a temperature in the 
range between about 425.degree. F. to 575.degree. F.; a chamber for 
enclosing the food product on the heatable surface under pressure; and 
means for introducing steam into the chamber during the caramelization of 
the food product. Preferably, the chamber comprising a food product 
containment chamber, a secondary steam chamber which is capable of 
preventing steam droplets from contacting the food product, and a means 
for applying physical pressure to the food product to ensure that the food 
product is in substantial contact with the heatable surface. 
Finally, the present invention also includes a system for high speed 
caramelizing of a food product which comprises: means for heating a heat 
transfer surface to a temperature between about 425.degree. F. to about 
575.degree. F.; means for placing at least one food product against the 
heated surface; means for enclosing the food product in chamber formed in 
part by the heated surface; and means for caramelizing the food product on 
the heat transfer surface under pressure and in the presence of steam for 
about 20 seconds or less.

DETAILED DESCRIPTION OF THE INVENTION 
FIGS. 1-4 show a preferred embodiment of a contact grilling apparatus 10 
which is comprised of a griller 12 having an assembly 14, which includes 
an upper portion and a lower portion, and which defines a chamber 15. The 
upper portion is comprised of an enclosure, here, a cover 16 closed and 
sealed against a portion of the lower portion comprised of a heated 
surface, preferably a platen 18 (dashed lines in FIGS. 2 and 3) and having 
a release material generally designated 20 thereon. The apparatus is 
mounted on a platform 22. Release material 20 can be any suitable material 
such as a coating or surface. Preferably, release material 20 is a sheet 
of Teflon.RTM.-coated fiberglass, preferably 3 milliliters thick, which 
can be purchased as TFE-Glass Fabric or as SRC-Glass Fabric, each is 
available from various distributors of industrial materials, such as 
McMaster-Carr of Atlanta, Ga. "Teflon" is the registered trademark of 
DuPont de Nemours and Co. A handle 24 is attached to an outer surface of 
cover 16. Release material 20 is removable to facilitate cleaning or for 
replacement. 
FIG. 4 shows griller 12 in the open condition. More particularly, FIG. 4 
shows that the chamber structure, here cover 16, preferably has associated 
therewith at least one pressure member, e.g., a pressure plate 26, adapted 
to apply pressure against a food product such as a bun when it is 
positioned on release material 20 and cover 16 is closed upon and sealed 
against heated platen 18 and/or release material 20. Chamber 15 is 
defined, in part, by the inside of the top and side walls of cover 16, 
their seals, and platen 18 and/or release material 20. Release material 20 
is considered a heated surface since heat provided by the underlying 
platen 18 is transferred to release material 20. Pressure plates 26 are 
associated with or mounted to chamber 15 in any suitable manner. 
Preferably, pressure plates 26 are adapted to and are attached to cover 16 
in a manner that allows them to float or move to accommodate and apply 
pressure equally or uniformly to all or a portion of the upper crown or 
heel surfaces of buns of different or irregular sizes and/or shapes or 
profiles placed on release material 20, including in positions not 
directly under pressure plates 26. 
In the preferred embodiment shown in FIGS. 4, 9 and 9, each pressure plate 
26 is affixed by welding to a centrally located bolt which extends 
perpendicularly up through an aperture in cover 16. The bolt passes 
through a washer 30 having a seal 32 (which can be a silicone material) 
(FIGS. 8 and 9) about its opening to seal heat and moisture vapor within 
chamber 15. The height of bottom face 34 of each pressure plate 26, 
relative to release material 20, is independently adjustable by nuts 36 
threaded onto bolts 29 and by wing nuts 38. 
Preferably, one pressure plate 26 is adapted to contact and satisfactorily 
compress those crown bun halves having an outer domed surface and the 
other plate 26 is adjusted to satisfactorily compress those heel bun 
halves having an outer more planar surface. Each pressure plate 26 
preferably has associated therewith, a self-adjusting structure such as 
one or more spring members 7 here shown as spring fingers 40 which are of 
equal lengths affixed, e.g., welded to the plates and calibrated to apply 
the desired uniform compression pressure against a portion or all of the 
top or crown surface of the buns to provide uniform contact, pressure and 
caramelization of the buns' cut surfaces against release material 20. Each 
spring forger preferably is tail wing-shaped and has a relatively wide 
base position welded to pressure plate 26 and a blade portion which 
narrows to a tip removed from the base. Spring fingers 40 need not touch 
but should be closely adjacent to, or preferably lightly in contact with, 
the inside surface of cover 16 such that each can independently and/or 
collectively bias all or a portion of the face of each plate 26 against an 
underlying bun. One or any combination of spring fingers 40 can contact 
the inside surface of cover 16, and thereby cooperatively bend or give 
toward plate 26 and thereby allow plate 26 to float to accommodate buns of 
different or irregular sizes, shapes and/or configurations, or buns not 
accurately positioned, oriented or centered directly under a pressure 
plate 26. 
With the adjustable feature or structure, plates 26 can apply uniform 
pressure against the bun, and provide uniform caramelization of the cut 
surface(s) of the buns, without damaging or disfiguring the buns. The 
faces of pressure plates 26 can be of any suitable size, shape or 
configuration. Preferably, they are flat or substantially flat and provide 
a continuous, uninterrupted or smooth surface (without markings), to avoid 
impressing markings upon the bun. Pressure plates 26 and spring fingers 40 
can be made of any suitable material. Preferably, the material is rigid 
and heat conductive. It has been found that 14-gauge stainless steel is a 
suitable material and functions well for grilling and uniformly 
pressurizing and caramelizing the buns. 
The grilling apparatus of this invention is provided with a source for 
supplying vaporized moisture into the chamber while it is closed and 
sealed, such that the moisture is effective in moisturizing and preferably 
maintaining the moisture content of the buns during grilling. As will be 
explained, the moisture is vaporized almost instantaneously and also adds 
heat to the chamber and the buns being grilled, thereby increasing the 
speed of caramelization of the buns. Although any suitable source, 
structure and manner can be employed for providing the vaporized moisture, 
preferably the moisture is introduced into the inside of cover 16 in a 
manner that the moisture does not directly contact the buns being or to be 
grilled, as it has been found that moisture droplets inadvertently 
deposited on the bun surface form unappealing whitish, prey or faded spots 
on the bun surface. 
Toward that end, preferably the inside of cover 16 is provided with a 
sub-chamber 15c which can be formed in any suitable manner. Preferably, 
sub-chamber 15c is defined by a divider wall 42, which can have any 
suitable location, size, shape or configuration sufficient to uniformly, 
indirectly (i.e., without directly controlling the buns) distribute or 
provide moisture within sub-chamber 15c during grilling. Preferably, 
divider wall 42 runs from a location adjacent the source along a portion 
or all of the length, width or periphery of cover 16. Preferably, divider 
wall 42 runs parallel to and adjacent the front wall of cover 16 and 
extends from one cover side wall to the other. As shown in FIGS. 3, 5 and 
7, the top edge of divider wall 42 does not communicate with the inside 
surface of the top wall of cover 16. Preferably, divider wall 42 is about 
1/2 the height of the inside of cover 16. The lower edges of the side 
walls of cover 16 and divider wall 42 are in the same plane and are 
provided with a suitable seal member for sealing sub-chamber 15c against 
loss of heat, energy or moisture when cover 16 is closed down against 
release material 20 and/or heating surface 18 during grilling. 
As shown in FIG. 4, a source of supply of a moisturizing liquid, preferably 
water, such as a tank or faucet (not shown) communicates with a conduit 44 
which in turn communicates with a valve, for example, an automatically 
controlled solenoid 46 and a suitable injection nozzle 48 for injecting 
water as desired into sub-chamber 15c. As shown in FIGS. 4-7, the orifice 
of nozzle 48 is located in sub-chamber 15c adjacent the side wall of cover 
16, between it and divider wall 42. The orifice preferably overlies an 
elongated reservoir or channel 50 formed in heated plate 18. The seals on 
the lower edges of the rear wall, side walls and divider wall 48 of cover 
16 circumscribe sub-chamber 15c above channel 50. As shown in FIG. 7, 
nozzle 48 injects water in a burst, as a continuous stream, or preferably 
in droplets, into sub-chamber 15c. The water droplets fall onto the heated 
surface of channel 50. When the water droplets hit the channel surface 
which is heated to a temperature in the range between about 425.degree. F. 
to 575.degree. F., the droplets instantaneously vaporize into steam. Since 
the lower edges of divider wall 42 and of cover 16 are sealed against 
heated surface 18 about channel 50, the steam rises through sub-chamber 
15c and passes over divider wall 42 and into chamber 15 above pressure 
plates 26. Heat from the steam (212.degree. F.) is transferred in part to 
pressure plates 26 which in turn heat the buns in the griller. With the 
steam in chamber 15, the temperature of pressure plates 26 preferably is 
about 200.degree. F. If the temperature of pressure plate 26 is too high, 
e.g., about 300.degree. F., the top uncut surface of the bun will tend to 
dry and change in appearance. The steam follows the contour of the main 
chamber 15, flows downwardly about and past the periphery of the 
respective pressure plates 26 and moisturizes and heats the buns without 
negatively affecting their appearance. 
The grilling apparatus of this invention can be operated manually or with 
any degree of automation. In the previously described embodiment, an 
operator of the grill would manually close cover or lid 16 by a handle, 
place the cut surface of the bun halves down onto the heated surface 18 
and close cover 16 to seal chamber 15 during grilling. Upon completion of 
grilling, the operator would manually lift cover 16 and remove the grilled 
caramelized buns. 
Those skilled in the art will understand from the teaching herein that 
various aspects of the grilling apparatus can be adapted to work 
automatically. For example, cover 16 can be opened and closed 
automatically at set time intervals sufficient for grilling the buns fed 
by an indexed or continuous conveyor. Thereafter, cover 16 can be 
automatically opened and the buns can be manually, semi- or fully 
automatically removed from heated surface 18. 
FIGS. 10 and 11 show an embodiment of a semi-automatic apparatus of the 
invention. More particularly, FIGS. 10 and 11 show a griller 100 comprised 
of a housing 102. Buns are manually or automatically placed cut side-down 
in a transport tray 104 which preferably is divided into two sections by a 
separator 106, one half of a cut bun being placed in each section. The 
tray preferably is heat conductive and can be made of or coated or treated 
with a release material. The loaded tray is then manually or automatically 
placed on a support member 107 at a landing station 108 at the front of 
the housing and manually or automatically moved from there onto heated 
surface or platen 118 in grilling station 110. As the tray reaches heated 
platen 118, grill cover 116, mounted to the housing by any suitable means, 
e.g., brackets 111, is moved automatically downward and closed to form a 
sealed grilling chamber which encompasses the loaded tray. As in the 
previous embodiment, once the sealed chamber is formed, the grilling 
process or cycle automatically commences. 
Moisture is introduced into the chamber through nozzle 148 which is 
attached to and extends through cover 116 into the chamber such that its 
orifice preferably overlies reservoir or channel 50. Water is injected 
from the nozzle onto the heated surface of reservoir 50 such that the 
water instantaneously vaporizes and adds heat to the processing chamber, 
pressure plates 26 and buns B, while adding moisture to the buns. When 
grilling is completed, cover 116 is automatically raised, and the loaded 
tray of grilled buns is automatically moved onto tray landing station 108 
to the rear of housing 102 where the buns and tray are exposed for easy 
manual or automatic removal from the apparatus. Once the grilled buns are 
removed, the tray or grilling chamber can be reloaded for the next 
grilling cycle. Any suitable mover (not shown) can be employed. For 
example, the mover can enter the grilling station area in the space at the 
rear of the tray, for example, between the rear of the tray and reservoir 
50, and can move the tray with the grilled buns thereon back to landing 
station 108. In another embodiment, the separator, or side, front or rear 
wall of tray 104 could serve as a divider wall in cooperation with a 
divider or other wall of cover 116 to form a sub-chamber for the 
previously described purpose. 
FIGS. 12 and 13 show another embodiment of an automatic grilling apparatus, 
generally designated 200, comprised of a housing 202 which includes a 
conveying system for moving buns into and out of grilling station 210. The 
conveyor system (also shown in FIG. 14) is comprised of a continuous 
conveyor belt 204 mounted about a pair of rollers 206 at least one of 
which is driven by means (not sown) to rotate roller(s) 206 and belt 204 
in a clockwise direction. A portion of the area of navel of belt 204 (left 
side of FIGS. 12 and 13) defines a bun receiving or landing area 208 
overlying a support member 207. 
The conveyor system includes one or more indexing ribs 209, preferably 
integral with, adhered to or otherwise permanently associated or 
cooperative with the exposed surface of belt 204 for defining the bun 
receiving or landing area. Ribs 209 protrude outwardly from the surface of 
belt 204 and extend vertically across or transverse to the width, i.e., 
across the conveying direction of belt 204, for retaining the buns on belt 
204 in a certain defined area such that they will be oriented for 
positioning under a pressure plate 26 during grilling. Ribs 209 also act 
as a back up or stop wall, to assure that if the buns slip or slide 
rearward on belt 204 they are positively physically engaged by ribs and 
are moved with the traveling belt along the conveying path into and out of 
grilling station 210, and thereafter into a bun collection tray 212 at the 
rear of housing 202. 
Collection tray 212 and/or the grilled buns can be manually or 
automatically removed from housing 202 through a movable flexible heat 
retaining curtain 214 mounted at the rear of the housing. Conveyor belt 
204 has a series of aligned, spaced water slots 216 cut through the 
thickness of belt 204 and extending in the conveying direction along the 
axial center of belt 204. Slots 216 are arranged so that they are 
positioned to a side of and between ribs 209 and help define the bun 
positioning area together with ribs 209. Slots 216 are spaced so that all 
or a portion of at least one slot overlies reservoir or channel 250 in 
heated platen 218 within the sealed grilling chamber when the conveyor 
belt 209 has indexed and positioned bun halves in the grilling station and 
chamber. 
As more clearly shown in FIG. 15, cover 116' has a sub-chamber 215c defined 
by divider walls 242. Nozzle 248 extends through the rear wall of cover 
116' and into the sub-chamber. As in the prior embodiment, when cover 116' 
is automatically closed and sealed against the underlying heated surface 
of belt 204 over heated platen 218 to form a sealed grilling chamber, 
water injected through nozzle 248 into sub-chamber 215c through slot 216 
and onto the heated surface of reservoir 250 instantaneously flashes and 
vaporizes to achieve the previously stated desired objectives. 
Belt 204 can be made of any suitable material. Preferably, it is made of 
the same material as employed as release material 20 shown in FIGS. 1-4 
and 7. It is to be noted that although it is preferred that slots 216 and 
reservoir 250 be elongated and positioned in the direction of the 
conveying path, they can be of other shapes and arranged in other suitable 
positions For example, they can be arranged vertically across conveyor 
belt 204. There can be one slot extending approximately across part or 
most of a width of belt 204, or there can be a plurality, preferably two 
slots spatially aligned end-to-end across a width of belt 204 (as are ribs 
209 in FIG. 12). These transversely arranged slots can be positioned to be 
aligned with and overlie a portion of one or more reservoirs 250 likewise 
formed transversely across most or a portion or portions of platen 18, 118 
or 218. Ribs 209 can be elongated and joined to form an extended rib (not 
shown) which would extend across most of the belt width. 
The ribs and/or slots can be cooperatively formed in any suitable shape, 
pattern or arrangement, e.g. V-, U-, conical-, circular-, or ring- shaped, 
etc. Regardless of their selected shapes or arrangement, the ribs and/or 
slots can be employed effectively in combination with conveyor belts, or 
movable indexing tables, trays, or other systems. The ribs need not be 
integral with the belt. For example, they can be integral with or affixed 
to a web which underlies the belt. Thus, a Teflon-coated belt can ride on 
a wire or mesh metal web having outwardly protruding metal ribs which 
extend through rib apertures in the belt. Metal ribs may be more suitable 
for durability than ribs formed of Teflon-coated fiberglass or the like. 
One or more elongated ribs can be used instead of or in combination with a 
cover divider wall, or alongside or in combination with a cover side, 
front or rear wall at file grilling station to form a sub-chamber for 
receiving water vapor from the heated surface and assisting in directing 
it upwardly into the grill cover and then throughout the grilling chamber. 
FIG. 16 depicts an automated embodiment of the grilling apparatus of the 
invention, here generally designated 300, which is similar to the 
apparatus shown in FIGS. 12 and 13, except that it has or is adapted to 
operate with an automatic bun feeding system, here shown as a bun feeding 
magazine M at the front or bun input end of the apparatus, and an 
automatic grilled bun discharge system, here shown as including a second 
conveying system cooperatively associated with a first conveyor system 
having the conveyor belt 204 shown in FIGS. 12 and 13. 
More particularly, FIG. 16 shows magazine M having a plurality of the crown 
halves of buns BC stacked cut surface down vertically on top of one 
another for easily feeding one bun at a time from the stack onto the 
conveyor belt 204, or a tray or other bun feeding device. Not shown, but 
behind this stack, there is another similar stack of the heel halves of 
buns. The magazine preferably provides a divider to maintain the stacks 
separate. The lower most bun is supported by any suitable support means, 
here one or more support members generally designated 51 (one shown) at 
the front and rear (not shown) of the magazine. The members support the 
stack thereon. Second support members 52 support the next higher bun. When 
desired, the members 51 are withdrawn and allow the lower most bun half to 
drop from the stack or stacks onto the bun receiving area of conveyor belt 
204. As the conveyor is conveying the buns first deposited onto the belt 
204 and/or during their grilling and/or caramelizing, the members 51 are 
reinserted into the magazine, and support members 52 are withdrawn to 
deposit the second bun onto first support members 51 which then are 
withdrawn to deposit this bun onto conveyor belt 204. The moving belt 
deposits buns cut surface down or up as desired on second conveyor belt 
304 which carries them out of housing 302 where they can be removed from 
the conveyor belt 304 or from an underlying platform for further 
processing. 
FIG. 17 is similar to the conveyorized bun handling grill shown in FIGS. 12 
and 13, but has the added features of thermally imprinted graphics 401, 
which show the operator how to properly space the buns in order to 
maintain consistent bun quality. Also, a bun receptacle 403 is provided 
with individual containers 405, 407 and 409 for receiving grilled buns. 
FIGS. 18-20 depict another embodiment of a conveyorized bun handling grill, 
wherein separate conveyorized systems are disposed adjacent to one another 
for moving buns from a loading station to a grilling station. The loading 
station moves buns B toward the grilling station via conveyor 411 which 
rotates belt 413 counter-clockwise towards the grilling station via 
rollers 415. When buns B reach the end of conveyor 411, they are 
transferred to conveyor 417 which rotates belt 419 counter-clockwise into 
position within the grilling station between housing 116' and heated 
platen 218 via rollers 421. Conveyor 411 is time delayed (not shown) so as 
to keep buns B in the grilling station for the require time to enable 
proper caramelization and conditioning of buns B before they are 
discharged from the grilling system. 
The apparatus of this invention can be operated in accordance with the 
unique method of this invention to condition buns (i.e., grill and 
caramelize buns rapidly with little moisture loss). According to the 
method of this invention, buns are grilled and caramelized rapidly at high 
temperatures for short times in a closed and sealed steam atmosphere. 
Because steam is used in the process, the high temperatures and short 
times are obtained and a high percentage of moisture is retained in the 
grilled buns. The method of the invention broadly comprises providing a 
bun having a cut surface, providing a surface which is heated at a 
temperature broadly of from about 425.degree. F. to about 575.degree. F., 
preferably from about 450.degree. F. to about 550.degree. F., and most 
preferably from about 475.degree. F. to about 525.degree. F., placing the 
bun cut surface-down against the heated surface, enclosing the bun in a 
closed sealed chamber formed in part by the heated surface, and while 
applying pressure onto a top portion of the bun to compress its cut 
surface against the heated surface, grilling the bun in a steam atmosphere 
for a period of time sufficient to caramelize its cut surface, the time 
period broadly being for 20 seconds or less, preferably less than 15 
seconds, and most preferably from about 8 seconds to about 12 seconds or 
less. Higher temperatures could be employed depending on various factors, 
such as the capabilities of the materials employed in the apparatus and 
the characteristics of the buns to be grilled. 
For example, the upper temperature of about 575.degree. F. is preferably 
since the practical upper temperature limit of the Teflon-coated 
fiberglass material disposed on the heated surface or platen is about 
575.degree. F. before such material starts to decompose. The use of very 
high temperatures within and beyond the stated range generally may also be 
limited by the characteristics of the bun to be grilled. For example, 
575.degree. F. generally would not be recommended for the relatively less 
dense, typically light, approximately 32% moisture-containing standard 
burger buns, particularly if these temperatures are held for relatively 
long times. At the stated temperatures, the period of time sufficient to 
caramelize the cut surface of the buns will vary depending on various 
factors again. For example, the characteristics of the buns to be grilled, 
their type, size, density, texture and ingredients, e.g., their fiber, 
sugar and particularly their pre-grilled moisture content. Generally, the 
higher the temperatures used, the shorter the time employed, required or 
desired, and vice versa. 
Buns can be satisfactorily grilled and caramelized at the stated 
temperatures within a sealed chamber for a time broadly ranging up about 
to 20 seconds or less. With the heated surface at about 575.degree. F., 
satisfactory caramelization of certain buns can be obtained in as little 
as about 8 seconds, while at the lower temperature of 425.degree. F. as 
long as 20 seconds may be required, e.g., for hard crusted, dense buns. 
However, extended times are not desired or required for caramelizing buns 
sold by most commercial fast food services. For such buns and/or services, 
preferred operating conditions would be about 450.degree. F., to about 
550.degree. F. for a grilling period of from about 8 to about 12 seconds. 
It has been found that the previously mentioned standard burger buns can 
be grilled and uniformly caramelized at from about 475.degree. F., to 
about 525.degree. F. for about 8 to 12 seconds with only 3% or less 
usually only a 1/2% to 1% loss of moisture. This is to be compared with 
conventional toasting devices wherein standard burger buns are caramelized 
at lower temperatures of about 350.degree. F., to about 450.degree. F. for 
longer times of from about 30 seconds to 45 seconds with a higher, about a 
5 to 7%, loss in moisture content. 
The lower heating platen 218 operating below and above these critical 
operating range of 425 to 575.degree. F. resulted in unacceptable 
caramelized textured surfaces. The upper compression plate which also 
provides thermal heat transfer was found to have an optimum range of 180 
to 240.degree. F. Lower temperatures resulted in bun crowns not achieving 
product temperature goals. Plate temperatures higher than 240.degree. F. 
resulted in toasting of the outer surface which is not desirable. Both the 
upper and lower surfaces require a release surface to prevent the product 
from sticking. 
A key element of the apparatus and method of the invention which permits 
obtaining caramelization at such high temperatures in such short times is 
that grilling and caramelization is effected in a closed or sealed steam 
environment. The buns are grilled in a sealed enclosure or chamber filled 
with steam. This adds heat to the system for higher grilling temperatures 
and shorter grilling and caramelization times, and provides and drives as 
much moisture as possible into the bun. This minimizes loss of moisture 
from the bun, or stabilizes, maintains, or perhaps even increases its 
moisture content especially if the pre-grilled moisture content is already 
relatively low. 
Heat from the steam also advantageously raises the temperature of the 
pressure plate whose face is in contact with a portion of the crown or 
heel of the bun half being grilled. This helps to rapidly raise the bun 
interval temperature from between about 150.degree. F. to 170.degree. F. 
which is required for caramelization. 
The amount of water provided and steam employed depends upon various 
factors such as the effectiveness of the seal of the grilling chamber, its 
size, the grilling time desired, the temperature provided to the grilling 
chamber by the heated surface, and the type, number and characteristics of 
the buns being grilled. Generally, the amount of water employed is the 
minimum amount which can be injected to rapidly provide the maximum of 
steam needed to fill the chamber at the beginning of the grilling cycle, 
and to maintain that filled condition for as long as needed during the 
processing cycle. If too much water is injected into the chamber, there is 
the risk that too much moisture will be driven into the bun and it will 
become overly moist or soggy and/or water droplets will occur on the bun 
surface and will change its color. 
Preferably, the steam is provided to the system as rapidly as possible. In 
accordance with the invention, it has been found that for caramelizing a 
standard burger bun (two halves), injecting 1/2 to 1 teaspoon of water per 
crown and heel into the sealed chamber in a manner which causes the water 
to instantly vaporize into steam has been satisfactory to rapidly 
caramelize the buns at temperatures and for the times mentioned above 
while minimizing moisture loss to about 3% or less, usually about 1% or 
1/2%. 
Although steam can be provided to the chamber by any suitable method and 
means, such as directly into file sealed chamber, it is preferred that the 
water be provided in the manner herein described directly into the sealed 
chamber and onto a portion of heated platen whose temperature is within 
the stated temperature range. This technique instantly vaporizes the 
water, instantly and uniformly fills the chamber with steam, rapidly adds 
heat to the chamber and bun and assists in caramelizing and rapidly 
driving moisture into the bun, without rendering the bun overly moist or 
soggy. The steam can be provided for any suitable length of time under the 
circumstances. It has been found that for grilling and caramelizing the 
halves of a bun with the first embodiment of the invention, when 1/2 to 1 
teaspoon of water is ejected into the sealed chamber, the water need only 
be injected under about 30 psi for about the initial 1/2 second of a 10 
second sealed grilling time for a standard burger bun. 
With such a burst, the 1/2 to 1 teaspoon of water is injected a sufficient 
distance along platen reservoir so as to instantly and uniformly vaporize 
the sealed chamber. The preferred approach of this invention avoids 
contacting the bun halves with water droplets as this tends to form spots 
on the him surface which are lighter in color than the rest of the crown 
or heal surface of the grilled bun. Instantly vaporizing water along an 
elongated highly heated reservoir surface and thereby instantaneously 
flash filling the grilling chamber with steam effectively prevents 
water-to-bun contact. The desired and achieved effect of the water 
injection is instantaneous total vaporization effected over an extended 
surface to uniformly distribute and rapidly fill the chamber with steam 
and retain that condition for as long a time of the remainder of the 
sealed grilling cycle as possible. The water injected into the chamber can 
be at any temperature. The heated surface, here the heated platen can be 
any suitable material, and heated by any suitable means. Preferably, the 
platen is made of aluminum which is cast with suitable electric resistance 
heaters therein. The channel or reservoir can be machined into a portion 
of the platen surface. For grilling and caramelizing two standard burger 
bun halves with the apparatus of this invention, the reservoir can be from 
about 1/4 to 1 inch wide and from about 1/8 to 1/4 inch deep. A suitable 
reservoir is about 1/4 inch wide and about 1/8 inch deep. 
The bun conditioning device of the present invention operates effectively 
by exposing the bun to a steam pressure during the grilling process. This 
steam pressure is developed by flashing a precise amount of ambient 
(75.degree. F.) water on to the hot platen 218 in a controlled area within 
the grilling chamber. This flash develops a burst of steam that diminishes 
during the grilling cycle. Peak pressures were recorded at 1/2 a lb. or 14 
inch-H.sub.2 O. This pressure peak varies depending on the volume of water 
injected and the temperature of the contact surface and the enclosure 
seal. The range of water volume that this device operates within is 
between about 1.5 grams to 5.5 grams per single bun (i.e., a crown and 
heel). For multiple buns conditioning devices the range of water set forth 
immediately above would be multiplied by the number of buns conditioned. 
Tests at the lower limits resulted in low product temperatures and greater 
moisture losses. The upper limits of water injection resulted in bun 
product having wet surfaces which were undesirable. 
A key element of the invention to obtain caramelization is the provision of 
compressive pressure onto an upper portion of the crown and for heel of 
the bun being grilled, to bring or force the bun's cut surface fully into 
contact with the heated surface. This contact is necessary to obtain 
caramelization of the cut surface. The pressure also reduces the time 
necessary to achieve caramelization. Preferably the compressive pressure 
is uniformly provided and distributed against the bun halves to provide 
uniform caramelization. Although the pressure plates can be of any 
suitable shape or profile, flat plates of greater breadth than the breadth 
of the buns to be grilled are preferred. Domed plates which would conform 
to the crown surface of buns are not desired for an ambient steam system 
because they would prevent ambient steam from being driven rapidly into 
the covered exterior portions of the bun. The height of each pressure 
plate of the invention can be pre-set to accommodate the height of the 
crown or heel portion of the bun under it such that each plate properly 
and sufficiently compresses the bun halves to be grilled and/or uniformly 
caramelized thereunder. Each plate though pre-set at a particular height 
is adapted to adjust or float to accommodate occasional unusual heights, 
profiles or locations of buns halves positioned thereunder. 
This bun conditioning device has a unique upper push plate within the 
grilling chamber which applies a force to the bun during the grilling 
process. This plate's finger springs are designed to apply an initial 
force that reduces during the grilling process. This initial force ranges 
from between about 3 to 6 pounds per square inch. The final force is 
mechanically stopped at a pre-adjusted gap setting, ranging from between 
about 0.312" to 1.000". Note that the bun profile or height determines the 
final gap requirement. This push plate also has the ability to conform to 
the irregular shape of a bun crown without damaging the shape. This was 
due to the pressure of the finger springs. Alternatively, a weighted plate 
may be used to allow gravity to force the compression. 
In accordance with the invention, the words "cut surface" of the bun are to 
be interpreted broadly to include the exposed interior surface of the bun 
obtained by any method and/or means, not just by cutting, as with a knife. 
Thus, the cut surface can be obtained by manually separating or pulling 
all or a portion of a bun apart, or by wedging the bun apart with say a 
fork, as well as by cutting. 
The apparatus of the invention can be operated with conventional devices, 
drives, systems and controls. These are not shown in the drawings. The 
apparatus includes a temperature control system which provides the platen 
and/or release material, preferably the platen, with a desired temperature 
which is set within the stated temperature range for the particular buns 
being grilled and/or caramelized. The set temperature preferably is 
maintained between grilling/caramelization cycles. A timing system is 
provided to control the grilling/caramelization time or cycle, that is, 
the duration of time that the cover is closed and sealed against the 
heated surface, the time period commencing on closure of the cover and 
terminating when grilling and/or caramelization is completed. With the 
manually operated cover, at the end of the set processing cycle, a cover 
latch associated with the timer and which locks the cover in the closed 
position, is released and the cover opens. In the automated versions of 
the apparatus, the timing system can be associated with an automatic cover 
control system to set the time of and to effect the opening and closing of 
the cover to correspond to or encompass the set time for grilling and/or 
caramelization. The timing system can also be associated with a moisture 
provision system which includes means for injecting water under pressure, 
for metering the amount of water injected, and for injecting it for the 
desired period, preferably at the commencement of file grilling cycle. One 
or more alarm systems, visual or auditory, can be provided to indicate to 
an operator when the grilling cycle starts and ends. 
While we have shown and described several embodiments in accordance with 
our invention, it is to be clearly understood that the same are 
susceptible to numerous changes apparent to one skilled in the art. 
Therefore, we do not wish to be limited to the details shown and described 
but intend to show all changes and modifications which come within the 
scope of the appended claims.