GB2179763A - Grilling apparatus - Google Patents

Abstract

A grilling apparatus for food has a set of heating elements for providing heat on each side of the food to be grilled and two spaced lattice members arranged one on each side of the food to slidably insert and remove the food from between the heating elements. A plurality of sets of heating elements may be provided so that more than one item of food may be prepared at the same time and an operator panel (3) connected to a microprocessor is arranged so that instructions may be inputted concerning the thickness of the food, the amount of cooking time and the required time whereupon the microprocessor is arranged to activate the heating elements such that the food for a particular place setting is completed at the same time. <IMAGE>

Description

SPECIFICATION Grilling apparatus This invention relates to a grilling apparatus for entree foods and particularly, although not exclusively, for grilling beef steaks.

It is common in present day practice for steaks to be supplied individually vacuum packed and chilled at a nominal 1"C and for the steaks to be placed in a refrigerator at 15"C at least one hour prior to cooking. It will however be realised that many deviations from this practice occur, so that steaks on commencement of cooking exhibit a range of exterior and interior temperatures. Each steak is usually of substantially constant thickness though steaks may differ from one another in thickness.

A typical known steak grill consists of a radiant panel arranged to direct heat downwardly towards an inclined metal grilling plate having a corrugated surface, which is for providing branding line marks on the steak being grilled.

A typical present-day grill unit may hold up to eighteen steaks and the grillling plate is usually inclined downwardly toward the chef so that fat runs down the grilling plate to the front into a collecting trough. The corrugated surface of the grilling plate of such a grilling apparatus becomes blackened in one day's use and such plates are replaced each day.

In cooking a steak the chef determines the thickness of the steak, the temperature required and the required condition or "doneness" of the steak. From this information the chef operates a cooking programme of action as follows: Place steak on grill, wait Turn steak through 90 , wait Turn steak over, wait Turn steak through 90 , wait Move steak to a cooler area, wait Remove steak to a plate.

As an example, to cook a steak of about 15mm thickness it is usually initially placed at the back of the grill and after 0.75 minutes it is rotated by the chef through 90". After 1.75 minutes the steak is turned onto its other major planar surface and at 3 minutes it is brought to the front of the grill. In 3.75 minutes from commencement of cooking it is finished to a medium rare texture. The 90" rotation provides the chequered pattern of branding lines from the corrugated surface of the metal plate.

Consider now by way of example a fillet steak that a consumer has ordered to be cooked rare. When the steak reaches the table its external appearance should be darkly coloured and charred with the branding marks. When the steak is cut its cross-section should exhibit a range of colours from dark brown on the outside surface to light brown, pink and at the centre, bluish pink. There will thus be a temperature gradient from nearly 100"C just below the surface down to about 60"C at the centre of the steak. The texture will range correspondingly from that of denatured tissue in the surface to that of almost raw meat at the centre. However even the surface must be succulent and not unduly subjected to loss of moisture. The flavour of the surface will be characteristically "roasted" whereas that of the centre will be "raw".

The grilling of such a rare steak is best achieved with a very high heat flux, that is between 20 and 30 kilowatts per square metre. At an early stage this heat tends to seal the surface, mainly by denaturing and drying protein material at the surface and exuding to the surface from inside the steak. Absorbed heat is then conducted inwardly. To minimise moisture loss the surface may be precoated with an edible oil or fat and as a further measure the heat flux may be reduced after an initial searing period. Ideally the applied heat flux should be sufficient to promote conductive heat transfer towards the centre of the steak without boiling the water present in the layer just below the steak surface. The final stage of cooking will occur after removal of the steak from the applied heat flux since conduction will continue to raise the temperature of the centre of the steak.

As yet another example, consider a rump steak that a consumer has ordered to be cooked well done. A similar external appearance will be required to that of the rare fillet steak described above but the interior of the rump steak should be uniformly light brown in colour. A reduced heat flux will be required by possibly for a shorter time if the rump steak is less thick than the fillet steak.

It will therefore be seen that the art of the chef lies in moving the steak between zones of different temperature, utilising different cooking times and employing conducted heat from the corrugated surface to cook the meat and to produce branding marks by turning the steak. The chef judges by appearance of the steak when to perform these actions and in all types of grill known to the applicants the chef has to exercise considerable art and judgment in order to serve items of high quality. It will further be realised that the chefs skill must extend to grilling various types of item to varying degrees of "doneness" determined on a rare through to well done scale at any one time. Furthermore the chef must also attempt to complete all the times ordered by consumers at one restaurant table so that the steaks are removed from the grill substantially simultaneously.

It will be realised that if a large number of steaks are being cooked at any one time and which are required in different batches and which each having different thickness and "doneness" requirements then a high degree of skill and activity is required.

In addition to requiring skill and judgment to use, present day types of grilling apparatus are inefficient in gross energy usage and emit heavy cooking fumes as well as requiring laborious cleaning.

The present invention seeks to provide a grilling apparatus which may be used by an unskilled chef.

According to this invention there is provided a grilling apparatus for entre foods including at least one set of heating elements arranged to provide heat on each side of the food to be grilled, supporting means arranged to insert and remove the entrée food into and from the heating means respectively, opearator panel means arranged to input instructions concerning the required condition of the food to a processor means arranged to control the heating means, whereby in dependence upon the input instructions so the processor means determines the cooking time of said food.

Advantageously there is provided two or more sets of heating elements, each set having an associated supporting means and in such an embodiment preferably the operator panel means is also arranged to input instructions to the processor means concerning the foods required in a particular batch and the processor means is arranged to control the heating elements complete the various cooking times of the individual entre foods at substantially the same time.

Advantageously said heating means is disposed in a substantially vertical direction and the supporting means is arranged to hold the entre foods with the major planar surfaces thereof in a substantially vertical direction. By supporting the entree food in a vertical plane the advantage is provided that if the entre food has a rim of fat and the fat is placed in the supporting means above the meat so in grilling the melting fat falls by gravity over the meat to achieve a selfbasting effect thereby reducing moisture loss and improving succulence. Moreover any molten fat or other liquid that drops from the food can be collected in a cool zone away from the hot surfaces of the heating means, thereby avoiding vapour formation and easing cleaning.

Where the thickness of the entre food is variable, preferably there is provided means arranged to determine the original thickness of the entre food and to input information representative thereof to the processor means.

If the initial temperature of the entrée food is variable, preferably there is provided means arranged to determine the initial temperature of the entre food and to input information representative thereof to the processor means.

Conveniently said one set of heating means comprises heat producing members disposed on each major planar side of the food to provide radiant and/or conducted heat thereto and the heat producing members may be, for example, ceramic encased electric heaters or resistive film heaters. Where sufficient ferromagnetic material is in contact with or in proximity to the food being grilled then electromagnetic induction heating may be used.

Advantageously the supporting means includes two spaced lattice members mounted to hold the entre food therebetween whereby the lattice members produce branding marks on the food.

Preferably the lattice members are mounted on a sliding frame arranged to slide between the heat producing members and conveniently one of the lattice members is fixedly secured to the frame and the other lattice member is movably attached to the frame to compensate for differing food thickness.

Preferably a drip tray is provided below the sliding frame for collecting exudate and melted fat.

Advantageously an odour absorbing unit is located above the grilling apparatus of this invention so that a ventilating flue as required in the prior art device described above is avoided.

Advantageously the entree food is beef steak The invention will now be described by way of example with reference to the accompanying drawings in which: Figure 1 shows a schematic perspective view of a grilling apparatus in accordance with this invention, Figure 2 shows a perspective view of one of the supporting devices in a withdrawn and open position.

Figure 3 shows said one of the supporting devices of Fig. 2 shown in a withdrawn and closed position, Figure 4 shows a device for measuring the thickness and temperature of a beef steak, Figure 5 shows a control panel and display of the apparatus, Figure 6 shows a block schematic circuit diagram of the grilling apparatus in accordance with this invention, and Figure 7 shows an alternative device for measuring the thickness and temperature of a beef steak.

In the Figures like reference numerals denote like parts.

The apparatus shown in Fig. 1 is intended pricipally for cooking beef steak and in the embodiment shown the ability to simultaneously cook thirty-six beef steaks is provided. The grilling apparatus has thirty six slidably arranged steak supporting devices 1 arranged in three rows, each row having the same number of steak supporting devices with the corresponding supporting devices of each row being aligned vertically with one another. The extreme end supporting devices of the top row are both shown in a slidably withdrawn position whereas the remaining supporting devices are shown in a closed position. The supporting devices each have a respective set of indicator lights 2 and at the right hand end (as viewed in Fig. 1) of the supporting devices is a control keypad 3 and a display 4.The supporting devices 1, indicator lights 2, control keypad 3 and display 4 are disposed in a vertical panel 5 mounted on the back edge of a base unit 6 having two shelves 7 and a working upper surface 8. On top of the panel 5 and extending forwardly thereof is a conopy 9 in which is located four odour absorbing units 10 and a steak thickness measuring and temperature sensing device 12 connected to the apparatus by an extensible lead 13.

The supporting device 1 shown more particularly in Figs. 2 and 3 has a fixed rectangular shaped lattice member 21 spaced from a rotatable complementarily shaped lattice member 22, both lattice members having the minor edges thereof vertically disposed. The fixed lattice member 21 is secured to circularly cross-sectioned rod 23 which acts as a slide rod for moving the supporting device into and out of the panel 5. The rotatable lattice member 22 is provided with a perpendicularly disposed base grill 24 upon which a steak 25 rests during the grilling operation. The rotatable lattice member 22 is connected by a cranked arm 26 to a handle 27, the cranked arm passing through a lower right hand portion of the front cover 28 and the rod 23 is fixedly secured to a top portion of a front cover 28.In Fig. 2 the cranked arm 26 and handle 27 is shown in full lines in an open position and in broken lines in a closed position of the lattice member 22. Underneath each lattice member 21 and 22 and extending the length thereof is a drip trough (not shown) which is also connected to the cover plate 28 and which is provided to collect molten fat from the steak during grilling.

For each supporting device and for each major planar side thereof there is provided two banks of silica tube heaters 30 within the panel 5, the banks 30 each being vertically arranged over a length at least the same as that of the lattice members 21. The supporting device 1 is arranged so that when inserted between the banks of heaters 30 the steak 25 is substantially centrally disposed between the heaters 30. It will also be noted from Fig. 3 that the steak 25 has a layer of fat 29 which during grilling is disposed on top of the steak.

The indicator lights 2 for each supporting device 1 have an escutcheon plate 40 carrying a red indicator light 41 and a green indicator light 42, and at the top of the escutcheon plate 40 is a reference numeral 43 indicating the number of the supporting device 1. The red indicator light 41 indicates grilling in progress and the green indicator light indicates grilling completed.

Thickness and temperature of a steak to be grilled is measured by the device 12 shown in Fig. 4 having a hollow handle 50 around the upper part of which is disposed a grip 51. The handle 50 is connected to a bridge piece 52 from which depend a pair of spaced spring biassed jaws 53, the lower ends of which are provided with perpendicularly disposed limbs 54. The grip 51 is biassed by a spring (not shown) away from the bridge piece 52 and the grip 51 is arranged to slide over the handle 50 and to be connected to a temperature probe 55 at the tip of a needle 56 which is normally located within the handle 50.

In operation, when the bridge piece 52 is pressed against the top of the lattice members 21, 22 the jaws 53 are arranged to spring inwardly (as shown by arrow headed lines 57) with a preset force to touch the outer sides of the lattice members and the displacement transducers thereby measuring the thickness of the steak and transmits signals representative thereof over lead 13 to a microprocessor computer 60 shown in Fig. 6. Depression of the grip 51 then pushes needle 56 and temperature probe 55 into the steak to measure the temperature of the coldest inner part of the steak. The temperature probe 55 also transmits signals over lead 13 to the computer 60.

A control panel comprising the control keypad 3 and display 4 will now be described with reference to Fig. 5. The control keypad 3 has four function keys 70-73 representative of the batch order number, the supporting device number, the condition or "doneness" and a start grilling key respectively. The keypad 3 also has'a block of twelve keys formed by a numeric keypad 74, a cancel numeric keypad key 75 and a key 76 for clearing the memory of the computer 60.

The display 4 indicates in a vertical format the supporting device (slot) number, the finishing time and the batch (order) number with steaks in the different slots which are of a similar batch (order) number being bracketed. The display also shows which supporting devices are being loaded and the finishing time of grilling for those steaks and the batch number. At the foot of the display the time of day is shown.

Referring now to Fig. 6, signals derived from the control keypad 3, the temperature probe 55, the transducers associated with the thickness measuring jaws 53 are all applied in parallel fashion to an anologue to digital- converter 61 which in turn provides input to the microprocessor control computer 60. The computer 60 which may be, for an example, an Apple II computer has a separate quartz oscillator timer 62 and memory storage provided by disk drives 63. The computer 60 provides output signals to the display 4 which may be formed of light emitting diodeds (LED's) or a liquid crystal display and to a digital to anologue converter 64 which in turn provides output to potentionmeters 65, 66 and 67 which each provide a different heat temperature to the heating elements 30. It should be here understood that only one of the groups of heating elements 30 is shown in Fig. 6 for clarity.

The operation procedure will now be described. For each steak of a batch a vacant supporting device is withdrawn from the panel 5 and handle 27 rotated to the position shown in full lines in Fig. 2 and a steak 25 is loaded onto the thus rotated lattice member 22 with the fat 29 of the steak located to the right (as shown in Fig. 2). The handle 27 is then rotated to the broken line position as shown in Fig. 2 and as shown in Fig. 3 and the temperature and thickness measuring device 12 is brought into contact with-the top of the lattice members 21, 22, depression of the grip 51 causing the spring loaded jaws 53 to move in the direction shown by arrow-headed lines 57 shown in Fig. 4 so that the jaws 53 and limbs 54 adopt the position shown in broken lines in Fig. 4. Also the temperature probe 55 located at the tip of needle 56 adopts the lower broken line position shown in Fig. 4.The grip 51 is then released so that the jaws 53 return to their full line position and the temperature probe 55 returns inside the handle 50. The thickness and temperature sensing device 12 is then released and the lead 13 retracts the device 12 upwardly toward the canopy 9.

The supporting devices 1 are then slid into the panel 5 so that the steaks are located substantially centrally between the heating elements 30 on each side of the associated steak and the operator then presses the keypad keys as follows: Press ORDER enter batch (order) number Press SLOT enter appropriate support device (slot) number Press CONDITION enter condition number on scale 1 very rare to 9 well done Press SLOT enter next appropriate supporting device (slot) number Press CONDITION enter required condition number Press SLOT enter another appropriate supporting device (slot) number Press CONDITION enter required condition number etc.

Press START (It will of course be realised that only one steak can be cooked in a batch if so required).

On pressing the START key the grill will commence the grilling programme in all the grill slots that have been instructed by the keypad. The computer 60 is arranged to automatically start grilling the steak which will take the longest time to cook with other steaks commencing grilling at such a time that all of the steaks of a particular batch or order are finished at substantially the same time.

The time for cooking is in accordance with the following algorithm: Total time=(steak thicknessX"doneness"Xkl)+ [thicknessXk2 (steak temperature-k3)] At any time when entering a particular number on the numeric keys 74 they may be cancelled by pressing key 55 and the whole order may be cancelled at any time prior to pressing the start button 73 by pressing key 75. The grilling instructions may also be loaded for a particular supporting device grilling slot position before inserting a steak.

The potentionmeters 65-67 are provided for the heating elements 30 so that grilling may commence at a high temperature and the temperature subsequently reduced.

An alternative steak thickness and temperature measuring device will now be described with reference to Fig. 7 in which there is provided a base 80 upon which the steak 25 is placed and a plate 81 is arranged to be lowered onto the top surface of the steak as shown in broken lines. A sharp temperature probe 82 is also arranged to be lowered with the plate 81 into the centre of the steak 25 as shown in Fig. 7. The plate 81 is connected to cantilever arms 83 which are arranged to drive a linear motion transducer 84 to indicate the distance between the movable plate 81 and the base 80 to thereby provide a signal representative of the thickeness of the steak.The temperature probe has an external form similar to a hypodermic needle with a thermister inserted at the pointed end thereof and the probe is held on the thickness measuring device in such a manner that its tip is arranged to be inserted to one half of the thickness of the steak being measured. Thickness and temperature outputs from the device are fed to the computer 60 as described above.

The plate 81 and probe 82 are arranged to be depressed by a spring biassed knob 85 and the plate 81 is arranged to be free to tilt, within limits, about two perpendicular axes so that an average thickness can be obtained for a tapered steak.

In a prototype the supporting devices were arranged to accommodate steaks of thickness from 12mm to 45mm and the distance from the steak surface to the heater elements varied from 35mm for the thicker steak to 50mm for the thinner steak.

It will be realised that instead of using an individual drip tray associated with each supporting device 1, a common drip tray may be used for each row of supporting devices. The rotatable lattice member 22 may be arranged to compensate for steaks of differing thickness.

It will also be realised by those skilled in the art that the grilling apparatus described herein could be constructed with an auto-eject system such that supporting device 1 would automatically be withdrawn from the heating elements 30 upon completion of cooking of the steak.

Claims (12)

1. A grilling apparatus for entre foods including at least one set of heating means arranged to provide heat on each side of the food to be grilled, supporting means arranged to insert and remove the entre food into and from the heating means respectively, operator panel means arranged to input instructions concerning the required condition of the food processor means arranged to control the heating means, whereby in dependence upon the input instructions so the processor means determines the cooking time of said food.

2. An apparatus as claimed in claim 1, wherein there is provided two or more sets of heating means, each set having an associated supporting means.

3. An apparatus as claimed in claim 2, wherein the operator panel means is also arranged to input instructions to the processor means concerning the foods required in a particular batch and the processor means is arranged to control the heating elements to complete the various cooking times of the individual entre foods at substantially the same time.

4. An apparatus as claimed in claim 3, wherein said heating means is disposed in a substantially vertical direction and the supporting means is arranged to hold the entrée foods with the major planar surfaces thereof in a substantially vertical direction.

5. An apparatus as claimed in any preceding claim, wherein there is provided means arranged to determine the original thickness of the entree food and to input information representative thereof to the processor means.

6. An apparatus as claimed in claim 5, wherein there is provided means arranged to determine the initial temperature of the entrée food and to input information representative thereof to the processor means.

7. An apparatus as claimed in claim 4, wherein said one set of heating means comprises heat producing members disposed on each major planar side of the food to provide radiant and/or conducted heat thereto.

8. An apparatus as claimed in any preceding claim, wherein the supporting means includes two spaced lattice members mounted to hold the entrée food therebetween whereby the lattice members produce branding marks on the food.

9. An apparatus as claimed in claim 8, wherein the lattice members are mounted on a sliding frame arranged to slide between the heat producing members.

10. An apparatus as claimed in claim 9, wherein one of the lattice members is fixedly secured to the frame and the other lattice member is movably attached to the frame to compensate for differing food thickness.

11. An apparatus as claimed in claim 9 or 10, wherein a drip tray is provided below the sliding frame for collecting exudate and melted fat.

12. An apparatus substantially as herein described with reference to, and as shown in, Figs.

1 to 6, or Figs. 1 to 3 and 5 to 7 of the accompanying drawings.