GB2326076A

GB2326076A - Apparatus for hot smoking of food products

Info

Publication number: GB2326076A
Application number: GB9712367A
Authority: GB
Inventors: Jr Robert Ritchie Spink; David William Brown Spink
Original assignee: R R Spink & Sons
Current assignee: R R Spink & Sons
Priority date: 1997-06-14
Filing date: 1997-06-14
Publication date: 1998-12-16
Also published as: GB9712367D0

Abstract

A kiln apparatus 1 comprises an enclosed smoking chamber 2 provided with a movable food support frame and entry and exit doors 8 for allowing entry and exit of the support frame. A fire box 12 is provided for containing an open fire. The fire box 12 is moveable from a first fire lighting position remote from the smoking chamber 2 to a second smoking position substantially below the movable food support frame in the smoking chamber 2. The smoking chamber 2 is provided with a closable fire box entry and exit 14 to allow the fire box 12 to be moved between the first and second positions in the kiln apparatus 1. A chimney 20 for exhausting smoke from the fire out of the smoking chamber 2 is provided. A control valve 22 for controlling the intake of air available to a fire in the fire box 12 in the smoking chamber 2 is provided whereby, in use, air available to the fire may be reduced so that the fire uses up the available air and is thereby reduced to fiercely glowing embers for hot smoking and cooking of a food product.

Description

APPARATUS AND METHOD FOR THE SMOKING OF FOOD PRODUCTS The present invention relates to a method and apparatus for smoking of food products and in particular fish, but not exclusively.

The smoking of food products has been known for many centuries and there are essentially two distinct methods of smoking food products - cold smoking and hot smoking.

The first type - cold smoking is when a food product is exposed to low temperature smoke, usually from a smoldering sawdust remote from the product, for a lengthy period of time and which gives the food product to be smoked a flavour of smoke only. At the end of such a cold smoking process the food product remains substantially uncooked. This type of smoking process is used for instance in the production of kippers, "yellow" fillets and other types of food products which require to be cooked before consumption. Cooking of the product kills most bacteria which may be present and such products are classed as "low risk" An example of a cold smoked fish product which is classed as "high risk" is smoked salmon which is eaten in a raw uncooked form.

The second method of smoking - hot smoking is where a food product is exposed to high temperature smoke for a shorter period of time than cold smoking such that at the end of the process the product is cooked and ready to eat. Examples of such products are the very well known Arbroath Smokie and other smoked cooked foods such as smoked mackerel. All hot smoked products are considered to be "high risk" and as with high risk cold smoked products it is essential that the methods and apparatus used in the manufacture of such products meets the very stringent compulsory food hygiene regulations.

The present invention is particularly directed to the Arbroath Smokie which is a traditionally produced specialty food product from the town and area around Arbroath, the Angus town on the east coast of Scotland. An Arbroath Smokie is a headed/gutted but otherwise whole small haddock which has been hot smoked in a manner handed down over generations of local fisherfolk. It is classified as a ready to eat product.

The initial preparation of an Arbroath Smokie involves a fresh haddock being gutted and headed and having its bell cavity cleaned so as to remove the black lining belly membrane and all traces of blood. After cleaning the fish are layered in dry salt and left for a period of around five hours depending upon the freshness and size of the fish after which they are tied together by the tails into pairs of fish of equal size. Salt is removed by dousing with cold water and the fish are suspended over triangular wooden rods where they are left to drip and dry for another five or so hours prior to smoking. The drying process is necessary to allow the outside skin of the fish to harden thereby lessening the risk of splitting during the high temperatures experienced during the smoking process.

Traditionally smoking was done in a wooden half barrel sunk in the ground outside a fisherman's home which were fueled by drift wood or fallen trees. The wooden half barrel has evolved into a more functional square and usually brick pit, still called a "barrel" and it is this form of hot smoking process that is still found in may backyards outside the homes of the many small fish smokers in the fishing area of Arbroath.

The smoking process involves a fire being lit in the bottom of the "barrel" using rough blocks of hard wood, usually oak or beech. Once the fire is burning the rods carrying the fish are placed over the fire in close proximity to each other. Layers of hessian cloth are then laid on top of the tails of the fish. The combined effect of the moisture released from the fish and the reduction of available air to fuel the fire is that the fire dies down to fiercely glowing embers with little actual flame. The fish cook in the heavily humid hot smoke. At the end of the hot smoking process the fish have taken on a rich dark brown colour and the fish is thoroughly cooked, moist and steamy hot and ready to eat.

Traditionally the length of the smoking process in heavily dependent on the weather conditions of the day. Should there be a brisk wind or a dry sunny day the fire will draft and burn strongly and the fish ready in for example half an hour.

Under these conditions however the barrel must be carefully monitored as it has been known for the barrel to explode into open flame. On the other hand, should the day be wet and cold with little air movement then the fire is reluctant to burn and it can take upto one and a half hours to smoke the fish, occasionally with very poor results. In the worst case the fire will extinguish itself completely.

The Arbroath Smokie is a traditional Scottish product which has a world wide reputation but the production requires considerable knowledge and experience. The small batch size and "cottage industry" status has limited the exposure of the Arbroath Smokie and is attraction to volume producers on the one hand and on the other hand its traditional method of production is almost wholly unacceptable to the modern food producer and the food technologists and hygienists insofar as its method of production is undocumented, uncontrolled and unaccountable to modern food hygiene regulations and thus unacceptable to supermarkets which set down very strict hygiene requirements in the production of food products.

Modern conventional kilns used for the hot smoking of other food products have been tested to see if the unique colour, taste, texture and characteristics of the Arbroath Smokie can be retained using such modern kilns and which can meet modern hygiene regulations but these attempts have failed to produce a product comparable with the traditionally produced product.

It is an object of the present invention to avoid or minimise one or more of the foregoing disadvantages.

In a first respect the present invention provides a kiln apparatus suitable for use in preparing a cooked smoked food product comprising an enclosed smoking chamber provided with a movable food support frame and entry and exit door means for allowing entry and exit of said support frame, and a fire box means formed and arranged for containing an open fire, said fire box means being formed and arranged so as to be moveable from a first fire lighting position remote from said smoking chamber to a second smoking position substantially below said movable food support frame in said smoking chamber, said smoking chamber being provided with a closable fire box entry and exit means to allow said fire box means to be moved between said first and second positions in said kiln apparatus; exhaust means for exhausting smoke from said fire out of said smoking chamber, air intake means for admitting air to maintain a said fire in use of the apparatus, and control means for controlling the intake of air available to a said fire in said fire box in said smoking chamber whereby, in use of the apparatus air available to the fire may be reduced so that the fire uses up the available air and is thereby reduced to fiercely glowing embers for hot smoking and cooking a food product.

Preferably said entry and exit door means comprises a first entry door on one side of said smoking chamber and a second exit door on the opposite side of said smoking chamber so that a food product may be loaded from a "low risk" food preparation side of the kiln into the smoking chamber and unloaded on the other side into a "high risk" food packaging area and so as to avoid any possibility of contamination.

Preferably said fire box means is provided with wheels, desirably wheels formed and arranged to run on tracks provided on the base of the kiln apparatus, to enable said fire box and a fire burning therein to be moved between said first and second positions.

Preferably said closable fire box entry and exit means is in the form of a hinged flap which is pushed open by the passage of the fire box between said first and second positions and closes under the action of gravity when said fire box has passed through.

Any suitable form of control means may be used though preferably said control means relatively movable apertures which overlap each other to a greater or lesser extent so as to act as a variable valve means to control air intake into said smoking chamber.

Said air intake means and said exhaust means may be formed and arranged separately though preferably said air intake means and said exhaust means are combined with said control means so as to control the air intake into said smoking chamber and thereby to control the rate of burning of the fire therein.

Preferably said exhaust means is in the form of a chimney desirably provided with an extractor means for exhausting smoke from said smoking chamber.

Preferably there is provided data acquisition means for monitoring variables such as temperature and humidity inside the smoke chamber which variables are measured and/or sensed by sensors inside said smoke chamber.

Preferably said fire lighting area is provided with a fire door and/or other fire extinguishing apparatus and equipment.

In use of the apparatus said fire door is desirably closed so that smoke from the smoking chamber is drawn out of the kiln apparatus through said exhaust means/chimney.

In another respect the present invention provides a method for hot smoking a food product comprising the steps: providing an apparatus according to the invention; supporting a food product to be smoked on said movable food support frame; introducing said movable food support frame and food supported thereon into said smoking chamber through an entry door means thereof; lighting a fire in said fire box means; moving said fire and said fire box from said first fire lighting position to a second position substantially immediately below said movable food support frame; controlling the intake of air into said smoking chamber so as to hot smoke said food product; moving said fire and fire box from said smoke chamber to said first fire lighting position; and removing said movable food support frame and food supported thereon out through an exit door means of said food smoking chamber.

Further preferred features and advantages of the present invention will appear from the following detailed description given by way of example of a preferred embodiment illustrated with reference to the accompanying drawing in which: Fig. 1 is a schematic diagram showing a smoking kiln apparatus according to the invention.

A smoking kiln, generally indicated by reference number 1, is a box type construction made of stainless steel and comprises a smoking chamber 2 which is situated inside the wall 4 of a factory and a fire preparation area 6 and woodstore area 5 which are situated on the outside of the factory wall 4.

The smoking chamber 2 has insulated hinged 7 doors 8, one on each side (only one shown here in the interests of clarity) to enable fish mounted on a movable support frame (not shown) to be wheeled in and out of the smoking chamber 2. At the base 10 of the smoking chamber 2 there is provided a wheeled fire box 12 which is movable between a position below the food support frame and the fire preparation area 6 outside the factory wall 4 for the lighting of a fire. A hinged closure flap 14 is provided at the base 10 of the smoking chamber 2 so as to allow the fire box 12 to be moved between the two positions and for enclosing a fire (not shown), in the fire box 12, in the smoking chamber 2.

The base 10 of the kiln 1 is open and has rails which pass over the open base 10 and on which the food support frame traverses. The base 10 of the kiln, which is concrete in construction, has a drainage aperture 16 to allow the kiln 1 to be cleaned and for cleaning liquids and other detritus to be drained away.

To produce an Arbroath Smokie according to the apparatus of the present invention'fish would be prepared according to the above noted traditional method and then hung on Teflon (Trade Mark) coated stainless steel hanging rods. These rods are then hung on the wheeled food support frame mentioned above which allows for a complete batch of fish to be smoked to be readily loaded and unloaded into the kiln 1.

As already noted the smoking chamber 2 has an entry door 8 which allows for the food product to be loaded from the "low risk" end of the operation where the raw fish are prepared and another similar exit door on the other side allowing unloading of the finished cooked fish product into the "high risk" side of the factory prior to being factory prior to being blast chilled and packed.

Once the fish to be smoked have been placed in the smoking chamber a fire is lit in the fire box 12, with the fire box 12 in the fire lighting area 6 of the kiln 1. (As shown in dotted outline on the enclosed Fig. 1). When the fire is lit smoke and heat from the fire is exhausted from the kiln 1 by a large fan 18 set into a wide chimney vent 20. Once the fire in the fire box 12 is burning the fire box is pushed through the closure flap 14 in the base 10 of the smoking chamber 2 and into position (as shown) under the fish supported on the food support frame in the smoking chamber 2.

As the fire box 12 moves into the smoking chamber 2 the closure flap 14 effectively encloses the fire and the fish within the smoking chamber 2 and more or less quickly the available air in the smoking kiln is used up and reduces the fire to fiercely glowing embers.

The ceiling 22 of the smoking chamber comprises two stainless steel flat plates one on top of another (shown in broken line) which have a plurality of more or less large holes drilled therethrough and which allow smoke from the fire to escape from the smoking chamber 2. These flat plates are moveable with respect to each other and are operable from outside the kiln so as to vary the amount of air available to the fire and thus controlling the burning of the fire to an extent not possible with conventional kilns. The smoke escaping through the ceiling 22 of the smoking chamber 2 is exhausted along a vent at the top of the smoking chamber and through into the chimney 20 for exhaustion by the fan 18.

A temperature monitoring and data acquisition apparatus 22 mounted outside the kiln records from sensors mounted inside the kiln the temperature profile of the whole process and an operator, by controlling the amount of air available to the fire and thus by adjusting the temperature of the smoking process, can ensure the food products are adequately cooked so as to kill any bacteria and in a controlled manner.

After about one hour the hot smoking process is complete and the fire box is removed from the base of the smoking chamber into the fire lighting position. The extractor fan 18 evacuates all smoke from the kiln and the smoking chamber before the "high risk" exit door is opened and the cooked food products into the "high risk" area removed for blast chilling and packing.

It will be appreciated that separate entry and exit doors are not strictly required for the kiln according to the present invention to operate. They are though included so that the kiln according to the invention can meet the very strict hygiene regulations.

The traditional characteristics of Arbroath Smokies made according to the apparatus of the present invention will be further explained in the following illustrative example.

Example 1.

Arbroath Smokies made according to the apparatus and method of the present invention were test tasted by an independent panel against "traditionally" produced Arbroath Smokies. The independent taste testing panel could not tell the difference between traditionally produced Smokies and Smokies produced according to the method and apparatus of the invention nor was any preference shown in favour of one or other of the Smokies.

Various modifications may be made to the abovedescribed embodiments without departing from the scope of the present invention. While the present invention has been developed primarily to address the problems associated with the making of traditional Arbroat'h Smokies it has been found that other food products including fish products such as trout smoked by the same method and apparatus of the invention is considered superior to other smoked trout products available using other hot smoking cooking processes.

Claims

1. A kiln apparatus suitable for use in preparing a cooked smoked food product comprising an enclosed smoking chamber provided with a movable food support frame and entry and exit door means for allowing entry and exit of said support frame, and a fire box means formed and arranged for containing an open fire, said fire box means being formed and arranged so as to be moveable from a first fire lighting position remote from said smoking chamber to a second smoking position substantially below said movable food support frame in said smoking chamber, said smoking chamber being provided with a closable fire box entry and exit means to allow said fire box means to be moved between said first and second positions in said kiln apparatus; exhaust means for exhausting smoke from said fire out of said smoking chamber, air intake means for admitting air to maintain a said fire in use of the apparatus, and control means for controlling the intake of air available to a said fire in said fire box in said smoking chamber whereby, in use of the apparatus air available to the fire may be reduced so that the fire uses up the available air and is thereby reduced to fiercely glowing embers for hot smoking and cooking a food product.

2. A kiln apparatus as claimed in Claim 1 wherein said entry and exit door means comprises a first entry door on one side of said smoking chamber and a second exit door on the opposite side of said smoking chamber.

3. A kiln apparatus as claimed in Claim 1 or Claim 2 wherein said fire box means is provided with wheels.

4. A kiln apparatus as claimed in Claim 3 wherein said wheels are formed and arranged to run on tracks provided on the base of the kiln apparatus to enable said fire box and a fire burning therein to be moved between said first and second positions.

5. A kiln apparatus as claimed in any one of Claims 1 to 4 wherein said closable fire box encry and exit means is in the form of a hinged flap which is pushed open by the passage of the fire box between said first and second positions and closes under the action of gravity when said fire box has passed through.

6. A kiln apparatus as claimed in any one of Claims 1 to 5 wherein said control means comprises relatively movable apertures which overlap each other to a greater or lesser extent so as to act as a variable valve means to control air intake into said smoking chamber.

7. A kiln apparatus as claimed in any one of Claims 1 to 6 wherein said air intake means and said exhaust means may be formed and arranged separately.

8. A kiln apparatus as claimed in any one of Claims 1 to 7 wherein said air intake means and said exhaust means are combined with said control means so as to control the air intake into said smoking chamber and thereby to control the rate of burning of the fire therein.

9. A kiln apparatus as claimed in any one of Claims 1 to 8 wherein said exhaust means is in the form of a chimney provided with an extractor means for exhausting smoke from said smoking chamber.

10. A kiln apparatus as claimed in any one of Claims 1 to 9 wherein there is provided data acquisition means for monitoring variables including temperature and humidity inside the smoke chamber which variables are measured and/or sensed by sensors inside said smoke chamber.

11. A kiln apparatus as claimed in any one of Claims 1 to 10 wherein said fire lighting area is provided with a fire door and/or other fire extinguishing apparatus and equipment.

12. A kiln apparatus as claimed in any one of Claims 1 to 11 wherein said fire door is closed, in use of the apparatus so that smoke from the smoking chamber is drawn out of the kiln apparatus through said exhaust means.

13. A method for hot smoking a food product comprising the steps: providing an apparatus according to Claim 1; supporting a food product to be smoked on said movable food support frame; introducing said movable food support frame and food supported thereon into said smoking chamber through an entry t door means thereof; lighting a fire in said fire box means; moving said fire and said fire box from said first fire lighting position to a second position substantially immediately below said movable food support frame; controlling the intake of air into said smoking chamber so as to hot smoke said food product; moving said fire and fire box fron said smoke chamber to said first fire lighting position; and removing said movable food support frame and food supported thereon out through an exit door means of said food smoking chamber.

14. A kiln apparatus for preparing a cooked smoked food product substantially as described hereinbefore and with particular reference to Fig. 1 of the accompanying drawings.

15. A method for hot smoking a food product using the apparatus substantially as described hereinbefore with particular reference to Fig. 1 of the accompanying drawings.