Food or edible material: processes – compositions – and products – Shaping by extruding into chemically reactive fluid – Forming edible packaging material – e.g. – casing – etc.
Reexamination Certificate
1999-12-29
2001-05-22
Corbin, Arthur L. (Department: 1761)
Food or edible material: processes, compositions, and products
Shaping by extruding into chemically reactive fluid
Forming edible packaging material, e.g., casing, etc.
C426S278000, C426S513000, C426S516000
Reexamination Certificate
active
06235328
ABSTRACT:
FIELD OF THE INVENTION
The invention relates to a process and apparatus for the production of co-extruded collagen coated foodstuffs such as sausages.
While the process relates particularly to the production of sausages, it may also be used in the production of other collagen coated foodstuffs such as fish or meat products or products containing vegetable or cheese or both. Thus, while the description of the process will be in terms of the production of strings of sausages, the process is clearly not limited to that particular foodstuff.
BACKGROUND OF THE INVENTION
There are known processes of co-extruding sausages or sausage-like materials. One particular process is disclosed in patent specification GB1232801. Essentially, the process involves extruding a cylindrical core of sausage meat mix and simultaneously extruding around the sausage meat an outer casing of a collagen gel. The collagen gel has a high water content and the gel is coagulated by removal of some of the water by osmosis by passage through a concentrated sodium chloride bath. However, coagulation of the collagen casing is not complete at this stage so that the casing is relatively weak in terms of mechanical properties. In particular, there would not generally be sufficient strength to enable crimping or twist linking to take place. In the conventional process, the co-extruded sausage is then cut into individual sausages which are transported to a hot air drying cabinet where the hardening of the casing is completed and at the same time some partial cooking of the sausage meat occurs.
This process is thus not suitable for the production of twist link sausages. At the end of the brine bath, the collagen casing has insufficient strength to allow twist linking to be successfully carried out. On the other hand, after completion of hardening of the casing, partial cooking of the sausage meat has occurred. A partially cooked sausage is unsuitable for twist linking, due to solidification of the sausage meat.
A further disadvantage of the conventional process is that the air drying stage is costly in terms of energy consumption.
Japanese patent application 63-219473 (publication H2-69139) suggests the addition of a liquid smoke solution into the collagen gel immediately prior to co-extrusion in order to overcome problems of splitting of the sausage casing during the air drying stage.
It is an object of the present invention to mitigate these problems and provide a process which avoids the costly air drying stage, and also allows the production of twist linked strings of sausages.
SUMMARY OF THE INVENTION
The present invention relates to a process of producing co-extruded sausage which comprises:
co-extruding a substantially uniform layer of collagen gel around an extruded edible product; and
chemically coagulating the co-extruded collagen gel using a chemical coagulating agent in the absence of heated air drying or forced air drying, such as to provide around the edible product a coagulated collagen casing of sufficient strength to allow mechanical separation into sausage links.
The invention also provides a corresponding apparatus for carrying out the process; and to the product itself.
DETAILED DESCRIPTION OF THE INVENTION
The term “coagulating” is a term of art in the production of collagen coated sausage material and is not strictly scientific in the sense in which it is used. Coagulating as used in this specification refers to the step involving hardening and stabilisation of the casing. This is principally achieved in two ways; firstly by removal of water from the collagen gel, and secondly by cross-linking the collagen. Either or both of these methods may be employed as appropriate.
Thus, it is known that collagen is a protein able to form aqueous gels of high water content. Typically, maximum gel water uptakes can be achieved at a pH of around 2 and a pH of around 13 which correspond roughly to the points of maximum swelling of the collagen protein. Higher water uptakes are generally found in the acid region and for this reason acid collagen gels are often used for extrusion purposes. Thus, coagulation of the collagen can be brought about by water removal from the gel, for example by the use of concentrated salt solutions (such as sodium chloride) which remove water by osmosis, or by the use of a solution which changes the pH of the collagen gel such that water is lost from the gel. Thus, one embodiment of the present invention, envisages the use of an acidic gel and an alkaline coagulation agent which neutralises the acid and leads to water loss in the gel (for example, a solution of sodium hydroxide, sodium carbonate, ammonium sulphate, sodium bicarbonate, or ammonium hydroxide; or even by means of gaseous ammonia). For example, an aqueous alkali solution of sodium carbonate of pH9 to 13 may be used.
Alternatively or additionally, coagulation may be brought about by means of chemical modification of the collagen, such as by cross-linking. Suitable chemical modification systems include the use of glutaraldehyde, glyoxal, liquid smoke, sugars and mineral tanning agents. Liquid smoke is a well known material in the art and is for example described in patent GB1432271. Modification of the collagen casing may be brought about by proteolysis, caramel addition, or by the use of modified polysaccharides, for example propylene glycol alginate or hydroxy propyl methyl cellulose. Cellulose fiber may also be added for certain cooking properties.
Certain chemical modifying agents are suitable for inclusion in the gel prior to extrusion, particularly cross-linking agents such as glutaraldehyde, and liquid smoke. Vegetable oil may be included in the gel to control coagulation and surface characteristics (such as clarity and permeability). According to a preferred embodiment of the invention, a coagulating agent which is a cross-linking agent (such as glutaraldehyde, glyoxal, liquid smoke, sugars and mineral tanning agents) is included in the collagen gel prior to extrusion, and the co-extruded collagen casing is then subject to coagulation by water loss in the post extrusion bath. This enables a coagulated collagen casing of sufficient strength to be produced, which may be twist-linked, crimped or otherwise mechanically separated into sausage links without breakage or disintegration.
The preferred chemical coagulating bath has a pH in the range 8 to 12, and preferably 9 to 10; and a temperature of 5 to 45° C., preferably 35 to 40° C.
The process is much less costly than the standard process because it omits the expensive and time consuming mechanical drying. Air drying is the most usual form of drying employed in conventional co-extrusion processes and it is the main feature which limits the speed of the process. Thus, the present invention not only produces a product which can be directly handled and/or hung but one which is much cheaper to operate than known co-extrusion processes.
Preferably, the collagen gel is an acidic gel at a pH of 1 to 4. Usually, the gel comprises 90 to 95% water. The collagen gel may be cooled to a temperature of 4 to 16° C. prior to extrusion.
A preferred collagen gel comprises 4 to 10% collagen, 0.1 to 2% cellulose, 0.05% to 0.5% hydrochloric acid, preferably 0.3%, the balance being water.
Colouring agents may be included in the casing, for example by incorporating a colouring agent in the gel itself, or within a crosslinking agent (such as liquid smoke) injected into the gel prior to extrusion. Alternatively, the colouring agent may be injected independently into the gel prior to extrusion thereof.
The co-extruded edible product may also be coloured if desired, depending on the desired appearance characteristics.
Suitable colouring agents are well known in the art and include, for example, annato, sunset yellow, curcumin, cochineal, tartrazine yellow etc.
Usually, the amount of collagen gel co-extruded around the edible product is 3 to 10% of the total weight of gel and edible product. Preferably, the finished coagulated collagen gel casing has a thickness of 10 to 30 microns. The thickness
Frame Gordon
Kobussen J. P. J.
Kobussen Petrus Johannes
Morgan Trevor Francis
Corbin Arthur L.
Devro plc
Kobussen J. P. J.
Pennie & Edmonds LLP
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