Electric heating – Heating devices – Combined with container – enclosure – or support for material...
Reexamination Certificate
1999-03-10
2001-01-23
Pelham, Joseph (Department: 3742)
Electric heating
Heating devices
Combined with container, enclosure, or support for material...
C099S386000, C099S349000
Reexamination Certificate
active
06177654
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a device and method for toasting food products, including products such as hamburger buns. More particularly, the invention relates to a contact toasting device and method that provides uniform and rapid toasting of food products that utilizes an improved heated platen.
BACKGROUND OF THE INVENTION
Various types of contact toasters are known. For example, U.S. Pat. No. 4,530,276 discloses a contact toaster having a housing with an inlet and an outlet in a toasting chamber defined therebetween. A platen capable of being heated is removably positioned within the toasting chamber in between a pair of conveyors intended to convey a product to be toasted along the heated platen. The platen is heated with cal rods or electrical resistance wires.
It is desirable to serve certain types of sandwiches, such as hamburger sandwiches, with toasted buns. Quick-service restaurants that serve such sandwiches often require a large number of toasted buns in a relatively short period of time in order to promptly satisfy customer demand. Consequently, rapid toasting of a large number of buns is desired for such restaurants. For example, a toast time of twenty seconds, fifteen seconds, eleven seconds, or even less, is desirable. To provide faster toasting, increased platen temperatures, for example, in excess of 500° F., and faster conveyor speeds can be utilized. However, rapid toasting must result in uniform toasting of the food product, even when the toasting device is operated continuously or substantially continuously, such as to achieve a high throughput of toasted products, without the occurrence of overtoasting or burning of any portion of the food item.
Consequently, a need exists for a conveyor contact toaster that is capable of rapidly toasting food items, including items such as hamburger buns, when operated under severe service conditions, such as when continuously or substantially continuously toasting food products, without burning or overtoasting of the food items.
SUMMARY OF THE INVENTION
In attempting to provide a conveyor toaster having a rapid toast capability, it was discovered that when the toaster was operated so that the throughput of food items was continuous or substantially continuous with overall heat input sufficient to maintain a desired temperature set point at a location along the toasting pathway, the buns became overtoasted; yet when the device was left running but operated with an intermittent throughput, such problem did not result.
It was discovered that the overtoasting was unexpectedly caused by a condition achieved during continuous or substantially continuous operation in which less heat was being transferred to the buns towards the end of the buns' travel along the toasting run or pathway of the platen and, coupled with the increased bun temperature along that portion of the toasting run, resulted in increasing and excessive temperatures at that portion of the platen.
In accordance with one aspect of the present invention, a device for toasting food products is provided. The device in accordance with the invention includes a toasting chamber having an inlet for receiving food items and an outlet for discharging the food items after toasting. The toasting chamber may be contained in a housing and includes a platen having a toasting surface defining a toasting pathway along which the food items are toasted and a conveyor for transporting the food items along the length of the toasting pathway. The platen includes heating structure for heating the toasting surface by application of energy to the platen. The heating structure is configured to provide a decreasing energy gradient in the direction of transport of the food items along the toasting pathway.
The energy gradient may be present along a portion of or along the entire length of the toasting pathway of the heated surface or platen. Generally, the presence of the energy gradient is most important towards the end of the toasting pathway such as about the last one-half or last one-quarter, for example, of the toasting pathway. This is because at high food product throughput, the platen temperature will increase most towards the end of the platen absent a decreasing energy gradient.
The energy gradient may be linear or nonlinear relative to the length of the toasting pathway. Generally, the energy gradient relative to the entire toasting pathway length will be at least 0.25 watts per square inch of platen surface area and, depending on the gradient desired, may be about 1, 2, or 3 or more watts per square inch of platen surface area relative to the entire toasting pathway.
In accordance with another aspect of the present invention, an energy gradient is provided such that when the device is operated to continuously or to substantially continuously toast the food items, the platen temperature varies less than 30° F. and more preferably less than 10° F. along the toasting pathway. To obtain a decreasing energy gradient, for example, more heat energy is applied to the platen per unit area along the initial portion of the toasting surface length compared to downstream portions of the toasting surface length. This may be accomplished in a number of different ways. For example, the heating element, such as an electrical resistance heating element can be configured to provide the decreasing energy gradient. That can be accomplished, for example, by controlling the resistance per unit length of the heating element so that less heat energy is applied at desired locations within the platen. For example, for a coiled heating element, more coils per inch increase the heat energy produced per length of the electrical resistance heating element and fewer coils per inch results in a decrease of heat energy produced per length traversed by the heating element.
Alternatively, to achieve an energy gradient decreasing in the direction of food item travel along the toasting pathway, a plurality of electrical resistance heating elements can be associated with the platen, with each element having the desired energy output to achieve the desired energy gradient.
The relative spacing of the heating elements (each of which may have the same heat energy output) can also be varied to provide a decreasing energy gradient, such as increasing the distance between heating elements in the direction of food item travel, provided that unacceptably high temperatures along the platen surface do not result.
In accordance with another aspect of the present invention, the platen temperature is monitored during use and the temperature of the platen surface is adjusted, usually by providing a decreasing energy gradient as described, to achieve a platen surface temperature in the desired temperature range. Any suitable temperature measuring device or devices can be utilized, such as one or more thermocouples. The temperature sensing device can be connected to a suitable temperature controller apparatus to regulate the amount of energy applied to a location or various locations along the length of the platen toasting surface.
In accordance with another aspect of the present invention, a method of toasting food products is provided. In one embodiment, the method includes providing a platen energy gradient decreasing in the direction of food item travel along the toasting pathway.
The decreasing energy gradient in accordance with the invention allows a contact toaster to toast food items rapidly and while operated in a manner in which food items are toasted continuously or substantially continuously, without causing the platen to overheat along the downstream or terminal part of the toasting pathway of the platen. For example, utilizing a platen temperature of about 540° F. to 560° F., hamburger buns can be toasted in about eleven seconds and the toasting device can be operated so that food items are continuously fed through and toasted by the device without excessive toasting or burning of the food products when the device is operated in such a manner.
The decreasing energy gradient chosen
Pelham Joseph
Restaurant Technology, Inc.
Ryndak & Lyerla
LandOfFree
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