GB2290460A

GB2290460A - The use of liquid nitrogen or a cryogenic gas to crack shells of food products

Info

Publication number: GB2290460A
Application number: GB9512767A
Authority: GB
Inventors: Ian Geoffrey Ferguson
Original assignee: HENNOTECH Inc
Current assignee: HENNOTECH Inc
Priority date: 1994-06-22
Filing date: 1995-06-22
Publication date: 1996-01-03
Anticipated expiration: 2015-06-22
Also published as: GB2290460B; GB9512767D0; GB9412577D0

Abstract

A method and device for breaking hard shells of food products eg. eggs or marine crustations comprises subjecting the hard shell of the food product to a stream of freezing medium eg. liquid nitrogen or a cryogenic gas such that a predetermined area of the hard shell becomes brittle and weak. The food product is subsequently mechanically agitated or struck such that the hard shell of the food product breaks along the brittle weakened area. <IMAGE>

Description

TITLE OF THE INVENTION LIQUID NITROGEN OR CO2 GAS SHELL CRACKING BACKGROUND OF THE INVENTION The present invention relates to a device and method for breaking hard shells of food products, for example egg shells.

Methods for breaking egg shells are conventionally applied in the large-scale processing of eggs. After the egg shell is broken, the content of an egg (the white and yolk) is separated. In a known method for breaking egg shells, a double knife (or scissor device) is struck through the egg shell and into the egg. The two knives of the double knife are then moved apart, which causes the shell to break open and the content of the egg to flow out of the shell. The egg content is then separated into its components through an unspecified known manner.

There are a number of drawbacks to the known methods for breaking egg shells. For example, during penetration of the egg, impurities found on the outer surface of the egg can be carried by the double knife into the egg. This can result in contamination of the contents of the egg, for example by salmonella bacteria. Moreover, since the double knife penetrates a large number of different eggs in rapid succession, there is a heightened risk of crosscontamination between eggs.

Additionally, the double knife penetrates the egg shell with relatively great force since the shell essentially must be drilled into. This forceful blow results in fragmentation in the area of the shell in question, so that shell fragments inevitably make their way into the content of the egg. Consequently, it is obvious that in practice the egg contents must be subjected to additional processing after being removed from the shell, such as a filtering process.

In addition, the penetrating double knife creates a rough fracture area with sharp edges, which results in the risk that on one hand the egg white will remain hanging on the sharp edges, and on the other hand that the yolk will break while flowing out of the egg shell. At the same time, the knife prevents the free discharge of the egg white, and adds the additional risk that the yolk will break on the sharp edge of the knife while flowing out of the egg shell.

An additional drawback of the known method is that the apparatus required for the conventional method comprises many moving parts and is thus susceptible to contaminants.

This is undesirable for hygienic reasons. Moreover, this apparatus generates a great deal of noise, not least of all through the breaking of the egg shells.

OBJECTS AND SUMMARY OF THE INVENTION It is thus a principal object of the present invention to provide a method and apparatus for breaking the hard shell of food products, for example the shell of an egg, by which the aforementioned drawbacks can be eliminated in a simple and effective manner.

An additional object of the present invention is to provide a method and apparatus for cleanly and effectively breaking eggs in a large scale food processing environment.

And still a further object of the present invention is to provide a method and apparatus for breaking the hard shell of marine crustaceans in an effective and clean manner in a large volume food processing environment.

Additional objects and advantages of the invention will be set forth in part in the following description, or will obvious from the description, or may be learned through practice of the invention.

In accordance with the objects of the invention, a method and a device for breaking hard shells of food products are provided. The method and apparatus are applicable to any process wherein the hard shell of a food product, such as an egg shell or the hard shell of marine crustaceans, must be broken without damaging or harming the food product within the shell. According to the invention, the hard shell of the food product is subjected to a stream of freezing liquid medium, such as liquid nitrogen or a cryogenic gas, in such a manner that a predetermined area of the hard shell becomes brittle and weakened. The food product is subsequently mechanically agitated or struck on the hard shell such that the hard shell breaks along the brittle weakened area. The apparatus and method are particularly relevant to a process for breaking egg shells and the hard shells of marine crustaceans.

A device or apparatus according to the invention includes a conveyor for conveying the food products along a path at a predetermined speed and orientation of the food product. A freezing chamber is disposed along the conveying path, with the food products being conveyed through the freezing chamber. At least one spraying device is disposed in the freezing chamber. The spraying device is in communication with a source of freezing liquid medium, such as liquid nitrogen or a cryogenic gas. The spraying device is configured to spray the freezing liquid medium onto a predetermined area of the hard shell of the food product causing this area to become brittle and weak. A mechanical breaking device is disposed operably downstream of the freezing chamber.The mechanical breaking device is configured to strike or otherwise agitate the hard shell of the food product thereby causing the hard shell to breakalong the brittle weak area.

The method and apparatus are explained below through the aid of the sole figure in the application.

BRIEF DESCRIPTION OF THE DRAWING The sole figure in the application depicts a preferred embodiment of the hard shell breaking apparatus according to the invention and also illustrates the method according to the invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Reference will now be made to the presently preferred embodiments of the inventions. One or more examples of which are illustrated in the accompanying drawing. Each example is provided by way of explanation of the invention, and not meant as a limitation of the invention. In fact, it will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the scope or spirit of the invention. For instance, features illustrated or described as part of one embodiment, can be used on another embodiment to yield a still further embodiment. Thus, it is intended that the present invention cover such modifications and variations as come within the scope of the appended claims and their equivalents.

The present invention relates to a method and an apparatus for breaking hard shells of food products. The invention will be described through the use of the sole figure in the application as a method and device for breaking egg shells. However, it should be understood that the invention is in no way limited to the breaking of egg shells and is relevant to any process wherein it is desired to break a hard outer shell of a food product in order to obtain access to the food product within. For example, the present invention is just as applicable to breaking the hard outer shells of certain marine crustaceans, such as lobsters, crabs, etc. Thus, the following description relating to the egg breaking device depicted in the figure is merely a description of a preferred embodiment of the invention and is not meant to limit the invention to the disclosed embodiment.

The device for breaking the hard shell of food products is illustrated generally as 10 in the figure. Device 10 comprises a conveyor for conveying food products, such as egg 14. Egg 14 comprises a hard outer shell 12. Conveyor 16 conveys food products 14 along a predetermined path 18 at a predetermined speed. Conveyor 16 can comprise any manner of conveying device, such as a conveying belt, chain, or any suitable conveying device. In the embodiment illustrated, conveyor 16 preferably comprises cups or recesses 19 formed therein for receipt of eggs 14. Conveyor 16 may include any manner of holding or positioning device to hold food product 14 at a desired position and orientation.

Eggs 14 are first conveyed to a pre-chilling unit 28.

Pre-chilling unit 28 is in communication with a cooling medium supplied by a chilling unit 27. The cooling medium and chilling unit may comprise any manner of conventional chilling or refrigeration systems. Eggs 14 are preconditioned or chilled in pre-chilling 28 before passing to freezing chamber 20.

Freezing chamber 20 is operably downstream of prechilling unit 28 such that eggs 14 are conveyed to freezing chamber 20 by means of conveyor 16 after being pre-chilled in chamber 28. At least one spraying device 22 is disposed in freezing chamber 20. Spraying device 22 is in communication with a source of freezing liquid medium 24.

The freezing liquid medium preferably comprises liquid nitrogen or a cryogenic gas. The freezing liquid medium may be in a liquid or gas state. For example, carbon dioxide gas or cryogenic gases may be utilized, but the cost of such gases is relatively greater than the use of liquid nitrogen.

Additionally, liquid nitrogen is already conventionally used in the egg processing industry at the present time for freezing egg products. Thus, most egg processing facilities already have a supply of liquid nitrogen installed therein.

In a preferred embodiment illustrated in the figure, spraying device 22 includes one or more spray nozzles 30.

Nozzles 30 may be disposed stationary within chamber 20, or may be movably disposed in the chamber so as to rotate or revolve around eggs 14. Nozzles 30 are disposed preferably so as to spray fine pulses of the freezing liquid medium 24 on a predetermined area of egg shell 12. Preferably, shell 12 is sprayed about or along its centerline axis. The centerline axis may be around the egg which sits in the cup in conveyor 16, or may be along the longitudinal direction of the egg. In this manner, it should be understood that nozzles 30 may be disposed in virtually any position within freezing chamber 20 so as to spray the hard shells of the food products at any desired location.

By subjecting the hard shell 12 of the food product 14 to the freezing liquid medium 24, the respective area of the hard shell becomes brittle and relatively weak.

A mechanical breaking device 26 is located operably downstream from freezing chamber 20. Food products 14 are conveyed to the mechanical breaking device 26 by means of conveyor 18. Within breaking device 26, the food products 14 are mechanically agitated or struck which causes the hard shell 12 to break or separate along the brittle weak area.

Mechanical breaking device 26 may include any manner of mechanical agitator or striking device, such as a hammer, pressure device, shaking device, or any other apparatus or device sufficient to cause hard shell 12 to break along the brittle weak area.

Once the shell 12 is broken along the brittle weak area, food product 14 may be subsequently conveyed to a further processing device (not illustrated) wherein the food product within the shell 12 is removed.

The present invention also includes the method essentially practiced by the device described above. The explanation of the inventive method is thus set forth in detail in the above description of device 10.

It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the scope and spirit of the invention. It is intended that the present invention cover such modifications and variations as come within the scope of the appended claims and their equivalents.

Claims

WHAT IS CLAIMED IS:

1. A method for breaking hard shells of food products, comprising subjecting the hard shell of the food product to a stream of freezing liquid medium such that a predetermined area of the hard shell becomes brittle and weakened, and subsequently mechanically agitating the food product such that the hard shell breaks along the brittle weakened area.

2. The method as in claim 1, comprising subjecting the food product to liquid nitrogen along a predetermined area of the hard shell.

3. The method as in claim 1, comprising subjecting the food product to a cryogenic gas along a predetermined area of the hard shell.

4. The method as in claim 1, comprising mechanically agitating the food product by striking the food product.

5. The method as in claim 1, wherein said method is configured for breaking egg shells.

6. The method as in claim 1, wherein said method is configured for breaking the hard shells of marine crustaceans.

7. A method for breaking egg shells, comprising subjecting the egg shell to a stream of freezing liquid medium such that a predetermined area of the hard shell becomes brittle and weakened, and subsequently mechanically agitating the egg shell such that the shell breaks along the brittle weakened area.

8. The method as in claim 7, comprising spraying the freezing liquid medium along the centerline of the egg shell such that the egg shell breaks along its centerline.

9. The method as in claim 7, comprising conveying the egg through jet streams of the freezing liquid medium.

10. A device for breaking the hard shell of food products, said device comprising: a conveyor for conveying said food products along a path at a predetermined orientation; a freezing chamber disposed along said path, said food products being conveyed through said freezing chamber; at least one spraying device disposed in said freezing chamber, said spraying device in communication with a source of freezing liquid medium, said spraying device configured to spray said freezing liquid medium onto a predetermined area of the hard shell of said food product causing said area to become brittle and weak; and a mechanical breaking device disposed operably downstream of said freezing chamber, said mechanical breaking device configured to strike or otherwise agitate the hard shell of said food product causing the hard shell to break along said brittle weak area.

11. The device as in claim 10, further comprising a pre-chilling chamber disposed operably upstream of said freezing chamber to pre-chill said food product with a cooling medium.

12. The device as in claim 10, wherein said freezing liquid medium comprises liquid nitrogen.

13. The device as in claim 10, wherein said freezing liquid medium comprises a cryogenic gas.

14. The device as in claim 10, wherein said spraying device comprises at least one nozzle configured to spray a jet stream of said freezing liquid medium onto the hard shell of said food product passing thereby.

15. The device as in claim 10, wherein said device comprises an egg breaking device.

16. The device as in claim 10, wherein said device comprises a marine crustacean hard shell breaking device.