Appliance to handle shortening

Abstract

Apparatus for managing melted shortening or lard for deep-frying purposes includes an upper tank holding melting elements and a lower tank for receiving melted fat, and a delivery pump, hose, and hand-held nozzle. Tanks are electrically heated and regulated. The melting elements have a large surface area and are designed to present the block of fat with a wide contact area of heated metal. The apparatus can be cleaned by boiling water within the lower tank. The mobile apparatus can be moved about a kitchen in order to load a cooking vessel with shortening and also includes collecting elements to receive used fat from underneath, or to pump from the cooking vessel.

Description

FIELD

This invention relates to apparatus for melting and holding fat, oil, shortening or lard for cooking purposes; also apparatus with a capability to receive and clean melted fat from cookers, with particular relevance to the fast-food industry.

DEFINITIONS

We use the term “shortening” to refer to any of the group: cooking oil, shortening, fat or lard used for deep-frying cooking purposes.

BACKGROUND

In a kitchen such as a fast-food restaurant where deep-frying is practised, a number of tasks involving handling bulk shortening (also known as fat or lard) are frequently undertaken. These tasks include:

1. Melting a new block of shortening (it may be 22-44 lb in size).

2. Holding the melted shortening in a tank ready for dispensing into cookers.

3. Dispensing the hot shortening into a hot cooker operating at typically 340-375 deg F.

4. Receiving already melted shortening from cookers for cleaning and eventual return.

Clearly those procedures involving oil do not require a melting step and do not include the risk of dropping a large (up to 50 lb) perhaps slippery mass into hot melted shortening. Williams et al (U.S. Pat. No. 6,330,852) state that “burns are commonplace in high volume food preparation establishments some of which lead to permanent disfigurement and disability”. In more detail the usual tasks are:

Task 1: It has been a problem to take a solid block of shortening, typically each block weighing about 25 lb, melt it (which can take about an hour and a half), and safely transfer the molten shortening into a cooking vessel such as a deep fryer, which is probably in use at the time. Simply placing the solid block into the cooker and waiting for it to melt is inadvisable because the flow of cooked product to the customers is interrupted.

Task 2: it has not been usual to be able to hold the shortening in liquid form in a tank able to be moved about. For instance there are safety aspects involved; risk of burning people, and risk of fire, as well as contamination aspects.

Task 3: In the past the melted shortening might be lifted in a saucepan or deep container of 10-20 litres capacity up to the hot fryer and tipping in some or all of the contents. There are significant risks associated with spilling the molten shortening, which is definitely hot enough at perhaps 250 deg F. to burn workers' skin, onto such as naked flames, or into water, when it may spit hot shortening and water about. The hotness of the contents may cause the person to be forced to drop the container.

Task 4: After extended use the cooker may need to have the fat removed again. There are single-purpose devices to receive hot shortening from cookers exist but the hot liquid has to be handled several times, and kept hot, before it can be returned to a cooker.

Any solution to the problem of handling bulk shortening should be cost-effective, safe, convenient, and hygienic. It is also desirable that it be “foolproof” in operation because of the likeliness of only limited training for operators and the ramifications of unintended spillage and of an industrial accident type of injury.

Prior-art patent documents have not emphasised the versatility envisaged in providing a device capable of serving the above functions in an existing kitchen. Hartzog (U.S. Pat. No. 3,466,997) provides a complex, integrated pressure cooking system for chickens using hot fat, including means to receive a block of solid cooking fat 92 into a tray with a thermostatically controlled heating coil below. Melting of solid shortening is mentioned in the background of Shumate et al, but is not dealt with in any of the following citations, which assume the use of cooking oil. U.S. Pat. No. 5,249,511 Shumate et al describes a permanently installed piping in a kitchen, running between the cookers (where it terminating in a flexible hose and valve) and a distribution and waste removal system. This involves a piping installation cost and an obligation of maintenance, and has the disadvantage that pipes will hold cold oil between operations. Grob et al in U.S. Pat. No. 4,974,501 provides a deep fat frying apparatus having two frypots and internal means for securely collecting and filtering used oil into an underneath-nesting collection pan. The cooker and the pan have independent sets of wheels so that the pan can be taken to a disposal site if the oil is to be discarded. A filtration system is built into the pan so that no extra floor space is required, but a special cooker is required. Bizard (U.S. Pat. No. 6,666,131) provides a similar device. Davis et al in U.S. Pat. No. 5,617,777 describe a similar though more automated cooker with integral collection. Dirck (U.S. Pat. No. 5,823,097) describes a wheeled, low-height (for gravity drainage) oil collection tank including a heater, filtering means and grinding means, for use with most types of cooker. Williams (U.S. Pat. No. 6,330,852) provides a mobile, heated oil handling system for taking oil to and filling an adjacent cooker and later pumping out the used oil for filtering and return, or for transfer to a disposal tank: also mentioning solid shortening in the background but again providing no means for melting it.

OBJECT

It is an object of this invention to provide improved apparatus for the melting, handling, storage and transfer of shortening about cooking facilities, or at least to provide the public with a useful choice.

STATEMENT OF INVENTION

In a first broad aspect this invention provides a powered appliance to service deep-fry cookers in a kitchen with a supply of liquid shortening (as herein defined) from time to time, and remove used liquid shortening from time to time, wherein the appliance includes internal means for melting a block of solid shortening, means for holding the melted shortening in a first internal heated chamber, and means for filling a cooker with the hot, melted shortening from the first internal heated chamber: the appliance also being provided with wheels so that it can be pushed up to the cooker to be serviced.

Alternatively the appliance comprises heated, mobile apparatus for supplying melted fat, shortening or lard for cooking purposes; wherein the apparatus includes at least one upper contained area holding melting elements capable of melting a solid block of shortening and at least one lower internal tank for receiving shortening in liquid form.

Preferably the internal means for melting a block of solid shortening employs a series of transverse bars forming a top surface for the internal heated chamber, each bar being internally heated and capable of bearing a solid block of shortening during a melting process.

A preferred element used to melt the fat comprises an array of upwardly directed, narrow-tipped, internally heated metal members having sufficient mechanical strength to bear the weight of a block of fat placed upon the narrow tips; so that in use the narrow tips melt their way towards the centre of the block and thereby apply heat throughout the block and melt the block more quickly and so that the heating elements present a larger heating surface area than that of a flat planar surface.

In a first related aspect each bar is heated by at least one internally located electric resistive element.

In a second related aspect each bar is ohmically heated by passage of a heavy current at low voltage through the surface material of the bar.

In a third related aspect each bar is ohmically heated by circulation of eddy currents within the bar, the currents being induced by an alternating magnetic field developed in proximity to each bar.

Optionally each melting element has a rectangular cross-section rather than a triangular cross-section.

Preferably the apparatus also includes a flexible hose connected to a powered pump adapted for the transfer of melted shortening into a cooker.

Preferably the flexible hose is terminated in a hand-held nozzle.

In a second broad aspect the appliance also includes means to receive hot used, molten shortening from below a cooker into a protruding heated container placed for the purpose at a low height above a floor, the appliance including a pump to lift the used shortening from the protruding heated container into an internal tank: the appliance also being provided with wheels so that the protruding heated container can be pushed under the cooker to be emptied.

Preferably the apparatus includes means for at least partially reconstituting the used melted shortening; such means including without limitation (1) physical filtering means, (2) chemical filtering means (such as activated charcoal), (3) gravity-settling separation means, (4) flotation purification means (such as using bubbles), or (5) centrifugation, along with means to physically dispose of contaminants.

Preferably the appliance includes a second internal heated chamber reserved for handling of used shortening: the first internal heated chamber of the appliance being reserved for use with new shortening.

In a related aspect the appliance includes a filter through which the used cooking oil is received so that filtered detritus may be removed from the used shortening and discarded, so that the shortening may be re-used if acceptable.

The preferred heating means is electricity, alternatively the heating means is a flammable gas.

Preferably the or each internal tank is electrically heated by means of electric elements and preferably the temperatures are regulated.

Preferably the internal tank and related parts of the apparatus can be cleaned by a process of boiling water within the tank.

Preferred Embodiment

The description of the invention to be provided herein is given purely by way of example and is not to be taken in any way as limiting the scope or extent of the invention.

DRAWINGS

FIG. 1: is a diagram showing an exterior view of the apparatus of Example 1.

FIG. 2: is a diagram showing a sectional view through part of an array of the fat melter elements.

FIG. 3: is a diagram showing some alternative fat melter elements.

FIG. 4: is a diagram showing another way to heat the fat melter elements.

FIG. 5: is a diagram showing alternative rectangular-section fat melter elements.

FIG. 6: is a diagram (Example 2) of an appliance including fat collection means.

FIG. 7: is a diagram showing detail of the fat collection means.

FIG. 8: shows another tray mounting means.

EXAMPLE 1

This Example (see 100 in FIG. 1) provides a movable appliance for:

1. Melting a new block of solid shortening (it may be from 20 to 50 lb in weight). (If oil is the starting point then melting is of course not required).

2. Holding the melted shortening in a heated tank ready for dispensing into one or more cookers.

3. Pumping melted shortening into a dispensing pipe and into a cooker.

4. Receiving used, melted shortening from cookers for cleaning, sieving the solids from the shortening which is held in the heated tank, and either returned to cookers or to a disposal tank if the shortening is not required for re-use.

(Optionally a second heated tank is provided for receiving used shortening, so that new shortening and used shortening are kept separate).

This invention comprises apparatus for supplying (meaning: first melting from the solid, then holding and supplying as a liquid) fat, shortening or lard for cooking purposes in premises such as a kitchen where deep fryers or the like require significant amounts of shortening to be provided for replenishment of their vats. The food being cooked absorbs some shortening. Over time, contamination of the shortening with fragments of food, carbonised material, and thermal degradation means that rejuvenation by filtering or replacement of the shortening will be required.

The apparatus 100 has an outer case 101 (preferably made of stainless steel and lined with thermal insulation) which includes at least one upper area in the form of an enclosed box 103 with an open floor and with a lid 102, the box surrounding the melting elements 202 (see below) that may have an optimised shape for promoting the speed of melting a typical 27 lb block of fat, placed at about the position of label 103 in FIG. 1, in about 20 minutes. Fat is a poor conductor of heat. Heat input is required in order to overcome the latent heat of fusion. Once melted, which occurs at a temperature of about 110-180 deg F., the liquid fat flows downwards into a lower, heated tank 105 in which it is kept molten at a temperature of about 180-250 deg F. Preferred “particular shapes” of the melting elements having narrowed tips 201 (which may be points or elongate ridges) is adapted to melt its way into the block of fat so that the distance that heat must travel through the block is reduced. Furthermore the shape of the elements increases the total contact area which comes into effect more and more as the block of fat continues to melt over the elements and sag into the intervening spaces. On the other hand a simpler cheaper shape such as a square bar (501-FIG. 5) holding internal heating means is adequately effective.

The weight of the block keeps the block in close contact with the elements. The melting elements 201-202 may be made of stainless steel sheet, folded and then welded together, (as is generally required in food-handling apparatus) and preferably an electric bar type heater passes along the interior. The upper box 103 and elements may be large enough to accommodate two blocks of fat at one time.

The preferred electric element 202 comprises at least one, and preferably more than two elongated members (as shown in cross-section in FIG. 2) mounted horizontally and having a working area that is triangular in cross-section; a vertex of the triangle being directed upwards (when in use) so as to form an upper narrowed contact surface, the elongated member having sufficient mechanical strength to bear the weight of a block of fat placed upon the narrowed contact surface. Other types of heater could make use of internal optionally wicked oil or other fluids as heat transfer agents and could be in the form of a plurality of vertically directed rods, but the preferred version is simpler and is not likely to release a heating fluid into the food-grade fat being melted if a seal should break. Both tanks are electrically heated by means of electric elements and preferably the temperatures are regulated. We prefer to use electric heating in this machine because of the fire risk of heating by flame, and because regulation and control can be managed more effectively by built-in means, suitable for use by unskilled operators. The machine can perform adequately using a single-phase AC mains supply, outlets for which are generally rated at 2500 VA maximum. (Three-phase outlets are rare and the internal controls required are more complex). Thermostatically controlled operation with more powerful heater elements allows the bars to reach a working temperature faster and hold that temperature closely, as compared to providing weaker heaters that are run continuously. A number of suitable thermostats are well known to those in the electrical trades.

The intention is that an unskilled operator can switch the machine on, put a block of fat in with no risk of splashing hot shortening, close the door, and do some other task(s) while the apparatus converts the solid block into molten shortening ready for delivery through the delivery hose without further attention. Preferably the upper box can hold two 27 lb blocks of fat at one time. Other sizes may be more convenient for other applications.

The lower tank (or container) 105 also has heating means 106 applied about its exterior in order to maintain the contents in a molten state, and typically this heating means is another electric element, regulated at a temperature sufficient to keep the fat molten even while it is being passed through a flexible delivery hose 108. The power rating of this element 106 is determined largely by the quality of the thermal insulation of the lower tank, but 500 VA would usually be sufficient. In a cleaning mode this element is used to boil a charge of water including a cleaning agent—surfactant or emulsifier—placed in the or each lower tank.

The apparatus also includes a flexible hose adapted for the transfer of melted fat. The outside of the hose is thermally insulated. The hose may include resistive heating elements within its wall in order to maintain any fat within in a melted state. Also, the delivery nozzle 110 should be hung up when not in use so that any fat within the hose can drain back into the system. The flexible hose 108, which is typically about 1.5 metres long, is terminated in a hand-held nozzle 110 having an exit valve. The hand-held portion 109 of the hand-held nozzle is also thermally insulated so that an operator can maintain a grip when the nozzle is in use without being burnt by the heat of the internal fat, or otherwise being forced to drop the delivery nozzle. There is an electrically driven pump 107 at the base of the hose, to force the fat out through the nozzle when the valve is held open. A preferred type of pump is a gear pump, (well known in the relevant arts)using metal gears, and is tolerant of possible solvent effects of molten fat. A return valve prevents pressure build-up at the pump outlet. A built-in rechargeable battery to power the pump is a useful feature, because the machine is moved away from its normal place to service a cooker and a mains power source requires a power cord to the nearest outlet. Alternatively a hand pump may be used, such as a foot-operated pump. Preferably the apparatus is provided with robust wheels 104 (some are steerable) and a handle 608 so that it can be pushed about a kitchen in order to approach a cooker and service it.

FIG. 3 shows cross-sections through some alternative melting elements. 301 (at left) indicates the straight sides of a first version that also includes three internal heaters such as 302 and 303. 201 is the upper tip. The version in the centre, 304, is a version with 240 curved sides, which should be stronger for a given thickness of stainless steel. This one includes to-and-fro rods of a resistance heater 306 near the tip 201, supplemented by further heaters near the base. The heating method of FIG. 4 leads to a desire to minimise the wall thickness so that greater electrical resistance per unit length is achieved, which is convenient. The right-hand cross-sectional outline 307 lacks internal resistance elements because the skin itself is the heater. This version also includes a dependent edge or ridge 308 intended to help the melted fat drip from the element (something that all versions may use). Note that all heating elements are relatively closely placed to neighbouring elements so that solid, un-melted fat does not escape from the first box 103 into the second box 105.

FIG. 4 shows an optional way to heat the melting elements at the element surface itself by the passage of low-voltage, high-current AC electricity (350 A for example) through the length of the series-connected array of shaped heaters 400. In FIG. 4, 401 is a connector to a controlled mains input, possibly including a regulator for controlling the heat, 402 represents a step-down transformer rated at typically 500 to 1000 VA or more, and with a low-voltage output of perhaps about 2 to 12 volts, driven from the local single-phase mains voltage (typically 100-120V or 220-250 V AC). The high-current output is connected to busbars 403 and 403′ which are connected to the array 400 of heating elements located inside a defining wall 406 of box 103. Each “element” is an empty shell of usually stainless steel having similar outline to the sections presented elsewhere in this specification. Intermediate busbars 405 connect one element to the adjoining one, all being wired in series. (The term “busbar” refers to a metallic connector having low losses at the intended current rating). This option provides for even heating and removes the thermal lag involved in heat transfer from an internal heater, by heating the contact surface directly. Internal elements are not required. User and repairman safety is ensured by use of only a low voltage. It employs the relatively high resistivity of stainless steel, as compared to copper. Although this option requires installation of a step-down transformer, it avoids use of a large number of internal bar heaters which are more likely to fail in use and hence cause some individual elements to be colder than the remainder.

An alternative heating means involves inductive heating in which eddy currents generated within the metal surface of the melting elements by means of alternating magnetic fields developed from transformer primary coils placed within cause resistive heating of the skin itself. As with the previous heating means, this has the attraction of practically instantaneous heat generation. It has the further advantage that there is no net flow of electricity into or out of any one melting element so that the apparatus need not be electrically bonded together. The primary coils, preferably within each melting element, are electrically insulated from the melting element. The primary coils may be fed with power at mains frequency (which may result in acoustic problems such as humming or buzzing from magnetostrictive effects). For compactness and quietness the primary coils may be fed with high-frequency power at 20 kHz or thereabouts generated within an on-board solid-state generator supplied with mains power. The power level is easily controllable.

The triangle or curved triangle sectional heated bar shapes of FIGS. 2 and 4 will be more feasible with volume production, while the shapes of FIG. 5 are easiest to make.

EXAMPLE 2

This Example (see 600 in FIG. 6 or FIG. 8) provides the same facilities as in the previous Example, and this Example also provides for a further task: Task 4. Receiving already-melted shortening (fat) from cookers for cleaning and eventual return, or disposal.

Cookers are usually made with valves underneath which allow the hot fat within to be drained away into a collecting pan beneath, so that the cooker can be cleaned out from time to time. The melter of Example 1 can be assigned an extra function: collecting used shortening from cookers and holding it either for purifying and return to the cooker, or for transport across the kitchen to a disposal tank. As compared to having a separate appliance for handling used fat, this combination reduces the capital cost of a kitchen and reduces the floor area taken up by appliances. Cost is further reduced when the same pump and the same tank system can be used for all the functions.

Referring to FIG. 6, one form has the melted fat/shortening collecting tray 601 extended from one lower side of the basic unit 600 on the far side from a steering handle 608. The tray may be provided with its own set of wheels 702 although short leg-type supports against inadvertent dropping below the horizontal may suffice. The tray is shown with its own heating means: bars 502 (here intended to raise the temperature of the fat as it arrives). An alternative site for a heating element is (as 703 in FIG. 7) in contact with and under the inner lining 606 so that the fat is kept hot as long as it persists in this compartment. FIG. 7 shows some details of the collecting tray. 703 is one site for a heater, bars 701 is another. It may be that a heater is not required, if the process of filtration can be carried out before too much time and hence cooling has elapsed, and providing that the fat as first collected is relatively hot. A heater makes the process less complicated for an unskilled user. 704 is preferably a layer of thermal insulation such as glass fibre.

The simplest way to rejuvenate used shortening is to filter it through a sieve and 603 represents a perforated intake around an inlet pipe 604 leading to a pump 605 suited for sucking melted fat through the sieve. A gear pump should suffice although some forms of gear pump need priming and the inventors are aware that some users of this equipment will be unable to manage priming using hot fat. Solid material may later be scraped off the sieve 603 by the operator, bagged, and thrown out. The outlet 607 of the gear pump is shown here leading into internal heated compartment 105. It may be preferable to have one separate compartment 105 for new shortening (as per Example 1) and another (105A, FIG. 8) for used shortening (as per this example and FIG. 8). Furthermore, there may be a need to apply further rejuvenating techniques to the used shortening, such as (1) further physical filtering means, (2) chemical filtering means (such as activated charcoal or a settling aid), (3) gravity-settling separation means, (4) centrifugation, or (5) flotation purification means (such as using bubbles) to encourage removal of detritus. None of these means are illustrated here.

FIG. 8 shows another tray mounting means. Here the tray 601 is pivotally (with a hinge 801) mounted onto the movable appliance. 601A shows the tray half folded back and the tray would lie vertically against the side of the appliance at 601B when fully stowed. Pipe 802 may be an extendable, flexible pipe, or a curled pipe so that it maintains integrity even after repeated folding and unfolding. 803 represents a spigot and drain for removing waste shortening from the heated container 105A. The pump 605 and the inlet sieve are not shown in FIG. 8, for simplicity. Nor do FIGS. 6-8 show the valves for changing the pump mode from (mode a:) pumping out or dispensing from compartment 105 into a cooker to (mode b:) retrieving fat from a cooker being emptied. An operator might empty a cooker from above by siphoning or suction into a temporary storage compartment, but this gives less opportunity to drain any sludge.

VARIATIONS

Improved resistive heating elements: FIG. 5 shows an array of box-section heating units 501, 502, 503 that may be substituted for the triangular elements of FIGS. 1-3. One or two (505, 506 as shown) elements may be included These shapes are easier to manufacture and are still adequate for the purpose. In FIG. 5, 500 indicates three heating units of an array of typically 6 units used together in one melter. Each unit comprises a rectangular tube 1 inch wide, 2 inches high, and about 2-3 feet long. Each unit is preferably made from type 304 stainless steel sheet 1.5 mm thick although these measurements are an illustrative example and may be varied, or given in integers of metric measurements or the like. The exterior finish is unimportant as long as it is cleanable and up to food regulatory standards. The interior may be made blackish so as to better absorb the radiated heat from the internal elements. Each unit is a sealed tube with welded-on end caps, and preferably contains only air because if an oil suitable as a heat transfer oil was to be included there is a risk that the oil may escape such as through a pinhole in the weld, and then into the food (the melting and melted fat). Each unit is supported at its ends and with its supports may from time to time bear the weight of a block of fat as it is dropped or pushed into the melter. Each unit includes 2×0.2 kW resistive heater elements for a total of 2.4 kW. The elements may be wired at the factory for example in series, in parallel, or as two groups of parallel elements; the groups being in series, in order to match the rated voltage of each individual element with the local supply voltage. Wiring methods should allow for field replacement of units having burnt-out elements.

The connection between the upper box and the lower box, past the heating units, may be made with a flap or other valve so that fat or odours cannot return and escape, even if the apparatus is inadvertently tipped over.

The same apparatus can be used to melt wax, such as paraffin wax or beeswax, in situations such as foundries or electric cable manufacture, where these materials are used in quantity. It may also be used to melt butter or fat in bakeries or other food factories, or to melt chocolate, or other foodstuffs without causing local overheating and degradation of the foodstuff through the Maillard reaction.

A gas or other fuel heated version could be made. Even though we consider that electricity is a preferable source of heating energy, in part because of the fire hazard, there will be sites where up to 2.5 kW of single-phase electricity is not available and a canister of gas (liquefied petroleum gas) is conveniently available.

INDUSTRIAL APPLICABILITY AND ADVANTAGES

Faster melting; instead of the nominal 90 minutes of prior-art fat melters, this device takes about 20 minutes to melt a standard block.

A user cannot splash hot fat and cause injury or fire by dropping another block into the apparatus because it will be caught, above the melted pool, by the melting heater which acts like a sieve. Delivery into fryers and the like without the user having to lift a container of melted fat up above waist height and pour. Instead, a hose and pump is used. The apparatus can be wheeled around, up to a fryer requiring fat. The thermally insulated hose and handle allows hot fat to be moved without causing burns to people.

Further, the capability to receive used fat allows management of a cooking installation to be run more successfully. The machine can receive fat out of a cooker so that the fat can be filtered and put back later, or put into another cooker, and so that the cooker once empty and cooled can be cleaned.

The electric heaters and controls avoid a fire risk inherent with use of gas or other flames. Regulated or controlled heat avoids overheating. The apparatus can be used to maintain hot fat ready for use.

The apparatus can be cleaned out from time to time by boiling a quantity of water, optionally including surfactants or other acceptable materials, in the or each lower container or tank. Hence the apparatus should be able to maintain acceptable regulatory standards of cleanliness.

Finally, it will be understood that those of skill will appreciate that various modifications, additions, known equivalents, and substitutions to the described embodiments are possible without departing from the scope and spirit of the invention as set forth in the following claims.

Claims

1. A powered appliance to service deep-fry cookers in a kitchen with a supply of liquid shortening (as herein defined) from time to time, and remove used liquid shortening from time to time, characterised in that the appliance includes internal means for melting a block of solid shortening, means for holding the melted shortening in a first internal heated chamber, and means for supplying a cooker with the melted shortening from the first internal heated chamber: the appliance also being provided with wheels so that it can be pushed up to the cooker to be serviced.

2. An appliance as claimed in claim 1, further characterised in that the internal means for melting a block of solid shortening employs a series of transverse bars forming a top surface for the internal heated chamber, each bar being internally heated and capable of bearing a solid block of shortening during a melting process.

3. An appliance as claimed in claim 2, further characterised in that each bar is heated by an internal electric resistive element.

4. An appliance as claimed in claim 2, further characterised in that each bar is ohmically heated by passage of a heavy current at low voltage through the surface material of the bar.

5. An appliance as claimed in claim 2, further characterised in that each bar is ohmically heated by circulation of eddy currents within the bar, the currents being induced by an alternating magnetic field developed in proximity to each bar.

6. An appliance as claimed in claim 2, further characterised in that the appliance includes means to receive hot used, molten shortening from below a cooker into a protruding heated container, the appliance including a pump to lift the used shortening from the protruding heated container into the first internal heated container: the appliance also being provided with wheels so that the protruding heated container can be pushed under the cooker to be emptied.

7. An appliance as claimed in claim 6, further characterised in that the appliance includes a second internal heated chamber reserved for receiving and holding used shortening: the first internal heated chamber of the appliance being reserved for use with new or unused shortening.

8. An appliance as claimed in claim 6, further characterised in that the appliance includes a filter through which the used cooking oil is received so that filtered detritus may be removed from the used shortening and discarded, so that the shortening may be re-used if acceptable.

9. An appliance as claimed in claim 7, further characterised in that the appliance includes a filter through which the used cooking oil is received so that filtered detritus may be removed from the used shortening and discarded, so that the shortening may be re-used if acceptable.