The present invention relates to a food preparation method and to a food preparation apparatus, more particularly a method and apparatus for preparing pre-cooked, packaged egg products, and to pre-cooked, packaged egg products prepared by such a method or with such apparatus.

Poached eggs have become an increasingly popular food item in recent years. Whilst they are tasty and nutritious, they are notoriously difficult to make consistently, as the white of the egg must be set, but the yolk should remain substantially unset, either liquid or in a soft, gel-like state. The difficulty arises at least partly because the proteins within the eggs set at different temperatures, and the temperatures needed to firm up the albumen (white) would normally start to gel/firm up the yolk if not controlled properly, which would detract from the quality of the eating experience. Such difficulties are exacerbated in the commercial production of poached eggs. However, there is evidence of demand for mass-produced poached eggs which deliver not only consistent eating quality (and soft yolk) but extended life (10 days or more) and to a standard/ format where the product can be safely consumed hot or cold, as a true ready-to-eat product.

Embodiments of the present invention aim to provide a method and apparatus of cooking an egg product in which the aforementioned problems are addressed. The present invention is defined in the attached independent claims, to which reference should now be made. Further, preferred features may be found in the sub-claims appended thereto .

According to one aspect of the present invention, there is provided a method of preparing a pre-cooked, packaged egg product, the method comprising the steps of de-shelling an egg, placing the egg in a sealed packaging pouch and performing a thermal treatment on the egg in the pouch so that the white of the egg is substantially set and the yolk of the egg remains substantially unset, but is pasteurised.

The thermal treatment may comprise several steps. At least one, and preferably more than one, of the thermal treatment steps may comprise heating the egg in the pouch. At least one, and preferably more than one, of the thermal treatment steps may comprise cooling the egg in the pouch. At least one step may comprise holding the egg in the pouch at a predetermined temperature for a predetermined period of time .

One or more of the thermal treatment steps may comprise exposing the egg in the pouch to steam to heat the egg. Preferably the method includes exposing the egg to a combination of air and/or steam and/or pressure in a thermal vessel. The method may comprise heating and/or cooling the egg in a retort or autoclave.

In a preferred arrangement, the method includes pre-charging the vessel with cooling water prior to a heating step. The thermal treatment may comprise one, more than one or all of the steps of: stabilising the egg to give a consistent start temperature, heating the egg to set the white, holding the egg at a predetermined temperature for a predetermined time, cooling the egg, pasteurising the egg yolk and further cooling the egg.

Preferably the stage of setting the white includes subjecting the egg to a predetermined combination of time and/or temperature and/or pressure, and more preferably a to a sequence including one or more steps of heating and cooling.

The pasteurising step preferably comprises exposing the yolk of the egg to a predetermined temperature for a predetermined time to reduce or substantially eliminate pathogens from the egg and to extend the shelf life of the packaged egg product.

The step of de-shelling the egg may comprise cutting the shell of the egg, more preferably with a rotary cutter. Preferably the step of de-shelling the egg comprises cutting the shell of the egg to a predetermined depth. In a preferred arrangement the shell is cut but the sub-shell membrane is not .

Preferably, the method includes determining the size of the egg and/or its location, more preferably using a laser reader device, prior to cutting of the shell.

The de-shelling step preferably comprises pulling two halves of the shell apart to release the egg from the shell. Preferably the step of pulling the two halves of the egg apart comprises gripping the egg with gripping means, more preferably suction gripping means. In a preferred arrangement the step of placing the egg in the pouch comprises depositing the egg into a pre-formed pouch. The egg may then be sealed in the pre-formed pouch with a sealing film. The method may comprise placing the cracked egg into the pouch using an automated/robotic device.

The method preferably includes the step of lubricating an inner surface of the pre-formed pouch. Preferably the method comprises the step of lubricating the surface of the egg in the pouch and/or lubricating the sealing film, prior to sealing the egg in the pouch with the sealing film.

According to another aspect of the present invention, there is provided apparatus for preparing a pre-cooked, packaged egg product, the apparatus comprising a de-shelling device for de-shelling an egg and thermal treatment apparatus for treating the egg inside a pouch, so that the white of the egg becomes substantially set and the yolk of the egg remains substantially unset but is pasteurised.

The thermal treatment apparatus may comprise heating/cooling apparatus arranged to apply to the egg at least one, and preferably more than one, thermal treatment steps in the pouch. The apparatus may be arranged to hold the egg in the pouch at a predetermined temperature for a predetermined period of time.

The thermal treatment apparatus may be arranged to expose the egg in the pouch to steam to heat the egg. Preferably the apparatus is arranged to expose the egg to a combination of air and/or steam and/or pressure. The thermal treatment apparatus may comprise a retort or autoclave. Preferably the thermal treatment apparatus is arranged in use to heat the egg to set the white, hold the egg at a predetermined temperature for a predetermined time, cooling the egg, to pasteurise the egg yolk and to further cool the egg .

Preferably the apparatus is arranged to set the white by subjecting the egg to a predetermined combination of time and/or temperature and/or pressure, and more preferably to a sequence including one or more steps of heating and cooling .

The apparatus may be arranged to pasteurise the egg by exposing the yolk of the egg to a predetermined temperature for a predetermined time to reduce or substantially eliminate pathogens from the egg and to extend the shelf life of the packaged egg product.

The de-shelling device may comprise a cutter that is arranged to cut the shell of the egg. More preferably the cutter comprises a rotary cutter. The de-shelling device is preferably arranged to de-shell the egg by cutting the shell of the egg to a predetermined depth. In a preferred arrangement the shell is cut but the sub-shell membrane is not. The apparatus may be arranged to determine the size of the egg and/or its location, more preferably using a laser reader device, prior to cutting of the shell.

The de-shelling device is preferably arranged to pull two halves of the shell apart to release the egg from the shell. Preferably the pulling of the two halves of the egg apart comprises gripping the egg with gripping means, more preferably suction gripping means.

Preferably the apparatus is arranged to deposit the egg into a pre-formed pouch. The egg may then be sealed in the pre formed pouch with a sealing film. The apparatus may be arranged to place the cracked egg into the pouch using an automated/robotic device.

The apparatus may be arranged to lubricate an inner surface of the pre-formed pouch, and/or to lubricate the surface of the egg and/or the sealing film prior to sealing the egg in the pouch with the sealing film.

According to a further aspect of the present invention, there is provided an egg product, comprising a set egg white and a pasteurised, substantially unset yolk within the white, sealed in a pouch.

The invention may include any combination of the features or limitations referred to herein, except such a combination of features as are mutually exclusive, or mutually inconsistent .

A preferred embodiment of the present invention will now be described, by way of example only, with reference to the accompanying diagrammatic drawings, in which:

Figure 1 shows schematically a method of preparing a pre cooked, packaged egg product, in accordance with an embodiment of the present invention; Figure 2 shows in perspective view a set of pouches for use in the method illustrated in Figure 1;

Figure 3 shows the set of pouches of Figure 2 in plan view;

Figure 4 shows the set of pouches of Figures 2 and 3 in side view;

Figure 5 is a view of two of the pouches with egg products sealed therein; and

Figure 6 is a schematic view of a retort, or autoclave, machine for use in the method illustrated in Figure 1.

Turning to Figure 1, this shows schematically generally at 100, the main steps of a method of preparing a pre-cooked, packaged egg product in accordance with an embodiment of the present invention.

Pre-production steps include the procurement of eggs from selected farms to rigorous standards 110, quality checks 112, the controlled storage of the eggs 114 and transfer of the eggs to the production line 116.

At step 120 the eggs are loaded into a de-shelling machine. At this point the pouches that will receive the eggs are thermo-formed 122 and a release agent is applied to an interior surface of the pouches 124. The eggs are then se- shelled by the de-shelling machine and loaded into the open pouches 126. The shell is cut, preferably with a rotary cutter, to reduce the risk of introducing shell fragments into the egg (in comparison with conventional impact cracking methods) .

A rotating blade scores the egg at its midpoint with a sucker arrangement to pull the two halves of shell apart with a clean, neat cut with minimal loose fragments. A laser device reads the size and concentricity of the egg and links to a servo motor which moves the rotating blade in and out to track the egg profile. In doing so, this complex operation helps to maintain a constant depth of cut regardless of egg size or positioning.

The depositing of the egg into the pouch is critical and should be done in a manner that limits damage to the egg structure and does not cause the yolk to become decentralised .

It is important that the yolk remains centralised within the albumen. The best way to do this is to replicate hand cracking and careful placement. Clearly, hand cracking eggs on a commercial scale is disadvantageous - not only because of the elevated risks of introducing shell, but also because throughput rates can be seriously compromised. If an attempt is made to load the egg via sliding chutes or similar, this adversely affects product quality as the yolk will be stripped from the white causing issues during cooking (once the yolk moves, there is a risk of excessive looseness within the white at the central point of the egg) . A further application of release agent to the upper surface of the egg in the pouch, and/or to an inside surface of a sealing thermo-film, is made at step 128 before the egg is sealed in the pouch using the thermo-film, under defined vacuum conditions, at step 130.

Individual pouches are then coded with traceability and identification details.

Sets of pouches, typically eight units joined together, are then loaded onto racks at step 140, which racks are then placed into a retort/autoclave for thermal treatment at step 142. There then follows a multi-stage thermal treatment process at step 144 involving the carefully controlled application of steam, air, liquid water and pressure in the autoclave. The stages may include: a stabilisation stage SI, a pre-heating stage S2, a heat-hold stage S3 in which the temperature of the pouch is held at a predetermined temperature for a predetermined time, followed by a pre-cool stage S4, a cooling stage S5, a cool-hold stage S6 in which the pouch is held at a lower, predetermined temperature for a predetermined time, and then a heat stage S7 followed by a pasteurisation stage S8 and a further cooling stage S9. It will be understood by those skilled in the art that the albumen (white) part of the egg also becomes pasteurised in the process outlined above.

After leaving the autoclave the pouches containing the egg products are blast chilled at step 150, before entering chilled storage at step 152, after which the pre-cooked, packaged egg products are coded (if not already coded at step 130) and checked for foreign bodies, as well as weighed at step 154, before packing into boxes 156, and coding/labelling at step 158. Storage begins with the steps of palletising 160, placing into a chilled store 162 and awaiting despatch at final step 164.

Figures 2-4 show pouches, generally at 200, for receiving the de-shelled eggs (not shown) . The pouches are thermo- formed from polyamide (PA) /polyethylene (PE) peelable film in sets of eight (alternative numbers could be used, and even individual pouches/eggs could be produced) . The individual pouches comprise a cup part 210 and a surrounding flange 212 and may be separated from the set by pulling along lines of weakness 214 formed between adjacent flanges.

Figure 5 shows two of the pouches in final form, with a film 216 thermo-sealed to the flanges 212, thereby sealing the egg (not shown) within the pouch. At one corner of each pouch a tab 218 of film is left free for ultimately peeling the film from the pouch to release the egg. The tab 218 can be provided with a printed image for easy identification.

Figure 6 shows schematically a thermal treatment apparatus comprising a retort, or autoclave, generally at 300. The retort comprises a chamber 310 and a closable door 320. In the schematic drawing the door 310 is open to show racks 330 of pouched eggs inside the retort. The retort is used to treat the eggs, sealed inside their pouches, with a combination of steam, air, liquid water and pressure, in timed segments, as described above with reference to Figure 1. During the pre-conditioning stage (where the retort stabilises temperature) , water is loaded into the device in advance of a formal cooling step and before the main heating stage starts. The purpose is to reduce the waiting time for the retort to fill from the mains supply once the machine calls for a "cooling stage". By reducing the waiting time, it is possible to rapidly stop the cooking of the eggs and prevent them over-cooking. Without pre-charging in this way, the initial cooling process would lengthen by 2 - 3 minutes, during which time the yolk may set to an undesirable level .

Other configurations of retort/autoclave could be used, including those with two (or more) doors which are able to span different production zones.

The multi-stage thermal treatment method allows for fine control of the cooking process, enabling the commercial preparation of eggs with a high degree of consistency, providing a cooked product that has the requisite set white and substantially unset/gel/liquid yolk, whilst always ensuring that food safety standards are met.

Whilst endeavouring in the foregoing specification to draw attention to those features of the invention believed to be of particular importance, it should be understood that the applicant claims protection in respect of any patentable feature or combination of features referred to herein, and/or shown in the drawings, whether or not particular emphasis has been placed thereon.