NL2009121C2

NL2009121C2 - Stabilized meat products.

Info

Publication number: NL2009121C2
Application number: NL2009121A
Authority: NL
Inventors: Johannes Martinus Meulendijks; Johannes Marinus Quirinus Kools; L On Marie Francois Spierts; Patricia Rosa Maria Hoekstra-Suurs
Original assignee: Marel Townsend Further Proc Bv
Priority date: 2012-07-04
Filing date: 2012-07-04
Publication date: 2014-01-07

Description

Stabilized meat products

The present invention relates to a method for preparing food products by means of processing food particles with a gelling agent, a device suitable for performing the 5 above described method, a food product obtainable with the method of the present invention and the use of an acidic buffer solution for stabilizing food products.

The general principle of producing foods by means of extrusion is already known in the prior art. It has become possible by means of extrusion to manufacture foods with a 10 specific composition and shape at a relatively high production speed. Extrusion is particularly a commonly used method in the production of sausage.

A particular form of extrusion is so-called co-extrusion. The principle of co-extrusion in food products is described in, among others, Netherlands patent NL 6909339. This 15 document describes the coating of a strand of food dough with a coating layer of collagen by means of co-extrusion. Following extrusion the coated strand is guided for strengthening purposes through a coagulation bath. Under the influence of the coagulation solution the collagen coagulates and/or precipitates and the coating layer is strengthened. A strand of food dough is thus formed which is at least partially coated 20 with a strong coating layer of collagen, i.e. casing.

Extruded food may also be used in moulding machines for moulding three-dimensional products from a meat mass or the like. International patent application WO 00/30458 A1 describes various methods and moulding machines for moulding products. For 25 example, US Patent 4,987,643 describes a moulding machine of the ‘slide-plate’ type, for the purpose of producing portions of hamburger meat. Another known type of moulding machine for meat products and the like is the ‘turrent-type’, see for example US Patent 4,193,167. Additionally, extruded food may also be used in ‘rotating drum type’ moulding machines. See for examples of ‘rotating drum type’ moulding machines 30 US 3,504,639, US 3,851,355, US 4,212,609, GB 2,259,043, FR 2,491,734 and FR

2,538223. In case of using moulding methods for producing food products, the extruded food fed to the mould cavities of the moulding machine must have a suitable viscosity to reduce the filling pressure needed to fill the mould cavities with a sufficient amount 2 of extruded food. In order to change the viscosity of the extruded food during the moulding process, collagen might be used.

In addition to proteins such as collagen, use is often also made in the food industry of 5 polysaccharides, such as alginate, as coating agent for foods such as for instance sausage. The term alginate refers to a group of naturally occurring polysaccharides extracted from seaweed. In the presence of alkaline earth metals (such as, among others, magnesium and calcium) alginates can form gels relatively easily. Collagen and alginate may also be used in combination as it is described in International patent application 10 WO 2006/135238 A2.

Studies have shown that the gelling of alginates under the influence of for instance calcium results due to the development of a three-dimensional structure. This is also referred to as the so-called egg-box model. When alginate is transformed into this three-15 dimensional structure, a relatively strong gel is created. Such a gel is highly suited to serve as coating layer of for instance a sausage or in providing extruded food products suitable for moulding machines.

In the co-extrusion practice a coating layer of alginate is often extruded onto a food 20 dough strand in the making of sausage. The coating layer of the at least partly coated strand is then strengthened. Guiding the extruded and coated strand through a salt bath containing calcium provides the strengthening. Due to the presence of the calcium the coating agent, e.g. the alginate, will gel quickly and a strong gel coating layer forms on the food dough strand.

25

In the moulding practice alginate or collagen is used to provide extruded food having a preferred viscosity. The extruded food may be strengthened subsequently by providing calcium to the food product.

30 A drawback however is that the initial strength of the alginate gel is weakened over time, e.g. 24 hours, due to metal chelating agents (e.g. phosphates) present in the food dough dissolving the divalent ion, e.g. calcium, which is bound to the gelling agent. The removal of divalent ions from the gel causes the gelling agent to swell and to disrupt. In 3 worst cases the gel disappears completely and consequently the co-extruded food or moulded food is no longer stable and falls apart.

An additional drawback of the alginate gel known in the art is that the gel as such does 5 not adhere to the food dough. As a consequence the cooking characteristics of a coextruded food product, e.g. sausage, are such that during cooking the gel coating does not shrink together with the food dough and that the cooking heat is not distributed through the food. This results in a heat build-up in the gel coating which causes unwanted deformation and discoloration of the coating due to evaporation of the 10 moisture in the coating. Furthermore, air bubbles may form between the food dough and the casing during cooking, which results in a less attractive product and/or insufficient cooking at least locally.

The cooking characteristics of a moulded food product, e.g. hamburger, may be such 15 that the product easily falls apart.

In view of the above there is a need to stabilize and increase the strength of the alginate gel applied to food dough to enhance storage duration. Increasing the amount of divalent ions, e.g. calcium, strontium, barium or combinations thereof, has been 20 provided in the prior art. However, an increased amount of divalent ions result in variations in taste, e.g. bitter taste, possibly a relatively high salt consumption and corrosion of the equipment.

Furthermore, there is a need of increasing the adherence between the gelling agent and 25 the food dough together in order to increase the cooking characteristics of the food product. The present invention provides a solution for both drawbacks.

The invention provides a method for preparing food products by means of processing food particles with a gelling agent, comprising the processing steps of: a) providing 30 food particles; b) providing a viscous gelling agent; c) treating the viscous gelling agent with an acidic buffer solution; and d) bringing the food particles in contact with the viscous gelling agent. This method enables the manufacture of food products that are stable over time. Additionally, due to the acidic conditions of the buffer solution the 4 viscous gelling agent is adhered to the meat via intermolecular hydrogen-bonding. The food products manufactured using the method according to the invention hereby have a good overall texture and in case of co-extrusion a well-constructed network structure of the coating layer and a good adhesion of the coating layer to the food dough.

5

The food particles as used in the method according to the present invention can be pieces of vegetable, pieces of meat such as minced meat, meat portions, pieces of chicken fillet, pieces of fish fillet and the like or can be in the form of food dough. The food dough can be manufactured from animal or vegetable products. The food dough 10 preferably comprises a combination of animal and vegetable products such as meat, fish, poultry, vegetable, soy protein, milk protein or proteins from chicken eggs.

The viscous gelling agent is suitable for extrusion of a coating layer. This preferably takes place by means of co-extrusion, however, the present invention also relates to the 15 extrusion of a coating layer and wherein the coating layer is subsequently filled with food particles. Furthermore, the viscous gelling agent may be mixed with the food dough. The gelling agent preferably comprises polysaccharides, proteins or combinations thereof. Polysaccharides, which can be readily used in the present invention, are agar, gellan, carrageenan, alginates, cellulose, pectin, xanthan and locust 20 bean gum or derivatives thereof. It is also possible to use a combination of these or other polysaccharides. It is also possible to use proteins in the gelling agent optionally in combination with polysaccharides. Proteins particularly suitable for this purpose are collagen, milk protein or derivatives thereof. It is however also possible to use combinations of collagen and milk protein. It is further also possible to make use of a 25 gelling agent comprising proteins such as collagen as well as polysaccharides such as alginate.

The viscous gelling agent may be a coating layer at least partially enclosing the strand of food dough and/or the viscous gelling agent may be mixed with the strand of food 30 dough. The resulting food product may be further coated with a coating material based on plastic at least partially enclosing the food product.

5

The acidic buffer solution as used in the method according to the present invention prevents ionic strengths differences between the food dough and the gelling agent. The acidic buffer solution has a pH in the range of about 3.0 and 6.0. Preferably the pH is in the range of about 3.1 and 4.5, more preferred the pH of the acidic buffer solution is in 5 the range of about 3.2 and 4.0 and even more preferred the pH of the acidic buffer solution is in the range of about 3.3 and 3.6. Most preferably the pH of the acidic buffer solution is about 3.5. The term “about” as used herein is intended to include values, particularly within 10% of the stated values, even more preferred within 5% of the stated values.

10

The acidic buffer solution can be made of several suitable buffering agents. In an embodiment the total concentration of buffering agents present in the acidic buffer solution is in the range of about 50 and 500 mM, since a too low concentration of buffering agents will provide a weak, drifting buffer, while a too high concentration of 15 buffering agents negatively affect the desired properties of the food product, such as taste. Preferably the concentration of buffering agents is in the range of about 100 and 400 mM. More preferably the concentration of buffering agents is about 100 mM, about 200 mM, about 300 mM or about 400 mM. Even more preferred the concentration of buffering agents is in the range of about 200 and 300 mM. Most preferred the acidic 20 buffer solution comprises buffering agents present in a total concentration of about 250 mM providing a good balance between the taste of the food product and the strength of the buffer.

In a further embodiment of the present invention the buffering agents are selected from 25 citrate and citric acid. Preferably citrate is added to the solution in the form of a salt, e.g. sodium citrate, calcium citrate or combinations thereof. Most preferably calcium citrate is used since calcium has a positive effect on the gelling agent strength. In case calcium citrate is used, additional strengthening steps may be avoided.

30 The acidic buffer solution described above may be used directly in a method for preparing food products according to the present invention or may be formulated into a gel or paste wherein the gel or paste comprises the acidic buffer solution of the present invention in combination with a thickener agent suitable for food products. Preferably 6 the thickener agent is a polysaccharide, e.g. starch. The advantage of using a gel or paste comprising the acidic buffer solution of the present invention is that the acidic buffer is released when heating the food product. Due to the delayed release of acidic buffer adherence of the viscous gelling agent to the meat via intermolecular hydrogen-5 bonding is even further established during preparation, e.g. cooking, of the food product enhancing the properties of the food product even further.

The extrusion of the strand of food dough and a coating layer extending there around preferably takes place by means of co-extrusion. A device and method here for has 10 already been described in U.S. Patent 3,622,353. In a preferred embodiment of the extruder the strand of food dough leaves the extruder via a first outlet in the case of coextrusion. Via a second outlet at least partially enclosing the first outlet the coating agent treated with an acidic buffer solution according to the invention is arranged on the strand of food dough such that a coating layer is formed.

15

In a preferred embodiment of the present invention the formed strand coated by and/or mixed with the gelling agent of the present invention is subsequently subjected to at least one strengthening step e) wherein the viscous gelling agent is treated with a liquid strengthening agent. The strand may be treated by spraying the liquid strengthening 20 agent onto the food product or by passing the strand through a bath comprising the liquid strengthening agent. Preferably the liquid strengthening agent is added to the viscous gelling agent during or after the gelling agent is brought in contact with the meat particles. Most preferred the liquid strengthening agent is added to the viscous gelling agent after the gelling agent is brought in contact with the meat particles.

25

The liquid strengthening agent of the present invention may comprise salt solutions. More specific the salt solution may comprise sodium salt, potassium salt, calcium salt, magnesium salt and/or combinations thereof. Specific salts which could be used are, among others, sodium chloride, potassium chloride, dipotassium phosphate, calcium 30 chloride, calcium lactate, calcium acetate or calcium phosphate. These salts are recommended because they are already much used in food products and because they have a positive effect on the strength and other properties of the coating layer. Calcium salts in particular such as calcium chloride, calcium lactate, calcium acetate, calcium 7 phosphate or combinations thereof have a great effect on the strength of the gelling agent, particularly when the gelling agent comprises polysaccharides such as alginate.

In a further embodiment of the present invention the liquid strengthening agent of the 5 present invention comprises a salt solution wherein the concentration of calcium salts is in the range of about 0.001 and 15% by weight, preferably in the range of about 0.01 and 10% by weight.

Particularly good properties are obtained when the liquid strengthening agent of the 10 present invention comprises salt solution comprising salts of sodium or potassium in addition to calcium. The sodium salt or potassium salt concentration of the salt solutions is preferably at least about 0.01% by weight. More preferred the concentration of sodium salt or potassium salt is in the range of about 0.01 and 5.0% by weight. The concentration of sodium and/or potassium in the strengthening agent may substantially 15 correspond with the concentration of sodium and/or potassium in the food dough. The transport of sodium and/or potassium ions from the gelling agent to the food dough, or vice versa, is in this way prevented from taking place.

It is possible to already add the liquid strengthening agent with calcium salts and 20 optionally, sodium and/or potassium salts to the gelling agent prior to and during extrusion of the strand. It is advantageous here to make use of salts which are relatively poorly soluble in water, such as calcium carbonate, calcium citrate, calcium oxide, calcium phosphate, calcium silicate, calcium sulphate, calcium sulphide, calcium tartrate or mixtures thereof. An advantage hereof is that a longer shelf-life of the gelling 25 agent is obtained due to the relatively slow release of calcium ions during storage of the manufactured food product, such as a sausage. In addition, the strengthening agent can also comprise (liquid) smoke, pyrolyzed sugars, cross-linkers and/or derivatives thereof.

In case of a non-moulding method, it is further recommended to divide the strand into 30 separate parts after step e) of the above stated method. This can be performed with for instance a knife, which cuts through the strand at determined adjustable intervals. Separate strand parts, such as sausages, are thus obtained. The method of the present invention may further include the processing of food particles comprising the portioning 8 of food products by use of shaping, e.g. rotational shaping or flat plate shaping. In contrast to the invention described in patent application WO 2009/145626 A1, it is not then necessary to divide the strand into separate units prior to the strengthening step. Higher production speeds can hereby be achieved, and a more uniform product is 5 obtained. Emptying of the outer ends of the separate parts (sausages) is also prevented.

Due to the use of an acidic buffer solution the treated viscous gelling agent adheres to the meat in the food dough. In case the food strand formed in a co-extrusion method is divided into separated parts, the adherence between the viscous gelling agent of the 10 present invention and the meat in the food dough provides a sausage of which the viscous gelling agent covers the outer ends completely.

Once the food strand comprising the treated viscous gelling agent has been formed according to above stated method, it is further recommended to perform an additional 15 stabilizing step to improve the stability of the gelling agent even further. In yet another embodiment of the present invention the above stated method further comprising an optional stabilizing step f) wherein the food product is treated with an acidic stabilizing solution increasing the storability time of the food product of the above stated method from about 4 to 5 days to about 2 to 2.5 weeks.

20

The acidic stabilizing solution of the present invention may have a pH lower than about 3.0. Preferably the pH of the acidic stabilizing solution is in the range of about 2.0 and 2.5. A preferred acidic stabilizing solution comprises citric acid, sulfuric acid, hydrochloric acid or combinations thereof. Since a preferred viscous gelling agent used 25 in the above stated method is sodium alginate, most preferred the acidic stabilizing solution comprises hydrochloric acid, due to the formation of sodium chloride. The strand may be treated by spraying the acidic stabilizing solution onto the food product or by passing the strand through a bath comprising the acidic stabilizing solution.

30 In another embodiment the processing steps a) - d) are subsequent processing steps.

However, for the method of the present invention it is not needed that the strengthening step and the stabilizing step are performed in immediate succession. In immediate succession is here understood to mean that either the strengthening step and the 9 stabilizing step are performed immediately one after the other or that one or more intermediate steps are performed between the strengthening step and the stabilizing step, but wherein the treatment time of the food particles in the combined intermediate steps amounts to a maximum of 300 seconds. Since the method including the 5 strengthening step e) already provides a stable product which is storable for about 4 to 5 days, the final stabilizing step f) may be performed at a later stage.

Following co-extrusion of the strand of food dough with a coating layer thereon, i.e. after step d) of the claimed method, in another embodiment of the present invention the 10 strand is divided into separate parts. This division into separate parts can take place using a knife as described above. After the strand has been divided into separate parts, these separate parts are subjected to at least one strengthening step and/or optional stabilizing step. In even a further preferred embodiment of the present invention the strand is divided into separate parts after further stabilizing the strand, i.e. after step f). 15

Therefore, the meat particles are formed in individual food products each assembled from food particles and gelling agent after step d), step e) and/or step f).

The treatment time of the strand in the strengthening step and optionally the stabilizing 20 step is preferably in the range of about 1 and 600 seconds, preferably in the range of about 1 and 100 seconds, more preferably in the range of about 1 and 60 seconds, still more preferably in the range of about 1 and 40 seconds, most preferably in the range of about 1 and 20 seconds.

25 The temperature of the strengthening agent in the strengthening step preferably lies in the case of so-called cooked products in the range of about 25 and 95 °C, preferably in the range of about 40 and 90 °C, more preferably in the range of about 50 and 80 °C, most preferably in the range of about 60 and 80 °C. In the case of non-cooked products the temperature in the separate strengthening steps lies in the range of about -5 and 30 300 C, more preferably in the range of about -2 and 250 C, even more preferably in the range of about 0 and 20° C, most preferably in the range of about 5 and 150 C.

10

The above mentioned temperatures are also suitable temperatures of the acidic stabilizing solution in the stabilizing step.

In a preferred embodiment the method of the present invention comprises a viscous 5 gelling agent selected from alginate, e.g. sodium alginate. Preferably the viscous gelling agent of the present invention comprises in the range of about 1.0 and 8.0% by weight alginate. In addition to alginate, the coating agent may also comprise hydrocolloids and proteins such as collagen or milk protein.

10 A relatively uniform coagulation of the proteins used in the gelling agent can for instance take place by making use of enzymes. Preferred enzymes are selected from transglutaminase, lactase, bilirubin oxidase, ascorbic acid oxidase and ceruloplasmin. Reference is also made in this respect to U.S. Patent 6,121,013, which is wholly incorporated here by way of reference.

15

Liquid smoke or derivatives thereof are particularly recommended as cross-linkers. An advantage of using these agents is that not only do they contribute toward controlling the structure of the coating layer of co-extruded food products, they also contribute toward the physical properties of extruded food products, e.g. taste.

20

As a consequence, in a further embodiment of the present invention the liquid strengthening agent in the strengthening step e) and/or the acidic stabilizing solution in the stabilizing step f) may further comprise an enzymatic solution and/or a cross-linker.

25 In a specific version of the method according the present invention during processing step d) the treated viscous gelling agent is at least partially enclosing the strand of food dough. The advantage of the above-described version of method is that the casing is sticking to the food dough during portioning of the resulting food strand, due to crimping of casing material comprising the treated viscous gelling agent. As a result, 30 better ended, e.g. non open-ended, strand portions, e.g. non open-ended sausages, are produced by the method of the present invention.

11

In yet another alternative version of the method according the present invention, the food products are prepared by means of extrusion whereby the viscous gelling agent is at least partially mixed with the strand of food dough. The method may also include the processing of food particles comprising the assembling of food particles. Even so the 5 assembling of food particles may be bound to each other by the treated viscous gelling agent before or during processing step d). Also the food particles may be injected with the treated viscous gelling agent.

In yet another alternative version of the method according the present invention at least 10 one electric property of the food particles and/or the viscous gelling agent is measured. Preferably the electric property is selected from ionic strength, conductivity and electrokinetic potential differences. The electric property may be measured by an intelligent control unit, e.g. a computer running suitable software, and the results are subsequently used for automated adaptation of the addition properties of the acidic 15 buffer solution used during processing step c). The term “addition properties” as used herein is intended to include changes in volume of the buffer added to the viscous gelling agent and/or changes in concentration of the buffering agents present in the acidic buffer solution.

20 In a further alternative of the method according the present invention the mechanical strength of the food particles and/or the viscous gelling agent may be measured. In more detail the mechanical strength may be measured by an intelligent control unit, e.g. a computer running suitable software, and the results are subsequently used for automated adaptation of the addition properties of the acidic buffer solution used during processing 25 step c).

Furthermore, the food particles used in the method of the present invention may be brought in contact with the viscous gelling agent during processing step d) in multiple stages. For example, the food particles may be brought in contact with the viscous 30 gelling agent in two or more subsequent steps by using one or more gelling agent baths and/or one or more steps of spraying of the viscous gelling agent onto the food particles.

12

Additionally the method according the present invention may further also comprise a brining step wherein the exterior of the food product is treated with an aqueous salt solution. The aqueous salt solution may be sprayed onto the food product and/or the aqueous salt solution is applied onto the food product by using a bath comprising the 5 brining solution.

The present invention also relates to a brining method for at least partially dehydrating the casing of a food product, comprising the processing steps of: x) providing a food product at least partially coated with a viscous gelling agent; y) providing electrodes; 10 and z) electrifying the food product. The expression “electrifying” as used herein is intended to include a method of conducting an electric current through or applying an electric potential across the food product and/or the brining bath. To speed up the brining time the electric current may be conducted through or the electric potential may be applied across the brining bath as described in the method in previous paragraphs.

15

Electric brining, e.g. DC brining, causes shrinkage of casing gel material applied to food products. In particular casing gel material comprising alginate are preferred in DC brining. The electrically induced shrinkage of casing gel material causes its texture to strengthen. Therefore, instead of using an aqueous salt solution sprayed onto the food 20 product and/or applying the aqueous salt solution onto the food product by using a bath comprising the brining solution, in addition or as a single treatment at least one pair of electrodes may be used to conduct an electric current through/applying an electric potential across the casing and food dough interface.

25 In a specific embodiment of the brining method according the invention the food product is partially coated with the viscous gelling agent and is interposed between a pair of electrodes and subsequently a DC current is applied. The DC current may have a field intensity within the range of about 25 to about 50 V/cm. More specific the DC current may have a field intensity within the range of about 30 to about 45 V/cm. Even 30 more specific the DC current may have a field intensity within the range of about 35 to about 40 V/cm, or within the range of about 25 to about 35 V/cm, about 30 to about 40 V/cm, about 35 to about 45 V/cm or about 40 to about 50 V/cm.

13

Preferably in DC brining the formation of gas is avoided. Such DC brining can be achieved by using polypyrrole electrodes further comprising a complex microgel of polymethacrylic acid and calcium ions.

5 In order to reduce the weight loss of the gelling material during the electrolysis a cross-linking agent selected from the group consisting of barium, calcium, iron ions or combinations thereof may be used. In case the gelling material comprises alginate barium is a preferred option.

10 The shape of the affected area of the shrunken gelling material resembles the shape of the electrode. In a specific alternative the electrodes used in the DC brining method further comprises pores of different dimensions along the lines of the electrodes.

In a preferred embodiment the method of the present invention further comprises an 15 electric brining step optionally in combination with a brining step wherein the exterior of the food product is treated with an aqueous salt solution.

The present invention also provides a device for preparing food products by means of processing food particles with a gelling agent according to the above described method. 20 In a specific embodiment of the device according the present invention the device comprises measurement means for automated measuring electric properties and/or mechanical strength of the food particles and/or the viscous gelling agent. The ionic strength differences of the food dough and the viscous gelling agent measured by the measurement means may be analysed by an intelligent control unit, e.g. a computer 25 running suitable software. To reduce the ionic strength differences of the food dough and the viscous gelling agent and to improve the stability of the viscous gelling agent, the ionic strength of the acidic buffer solution may subsequently be automatically adjusted by the intelligent control unit and the viscous gelling agent is subsequently treated with the automatically adjusted acidic buffer solution.

30

In a further alternative embodiment of the device according the present invention, the device also comprises an intelligent control unit for automatic adjustment of the ionic strength of the acidic buffer solution. This provides the opportunity, in case the 14 difference in ionic strength of the food dough and the viscous gelling agent changes during the extrusion process, to adjust the ionic strength of the acidic buffer solution accordingly to prevent ionic differences to occur within the extrusion process.

5 The acidic buffer solution may be added to the viscous gelling agent before or during the forming of a casing, or alternatively or in combination, be mixed with the food particles. Furthermore, in case of co-extrusion the acidic buffer solution may be added onto the outer layer of the food dough formed by the food particles and wherein the coated food dough is subsequently co-extruded with the viscous gelling agent to form a 10 food strand. The food strand comprising a core of food dough and two coating layers wherein the first layer comprises the acidic buffer solution and the outer layer comprises the viscous gelling agent. In a preferred embodiment the food dough is co-extruded with the acidic buffer solution, optionally in the form of a gel or paste, and the viscous gelling agent simultaneously to form a multilayered food product.

15

The present invention also provides a food product obtainable with the method according the present invention. In a specific embodiment, the food product relates to an at least partially coated food strand. The food product may be in the form of sausages, injected products, assembled food products, portioned food products, meat and fish.

20

The present invention furthermore provides the use of a buffer solution for stabilizing a viscous gelling agent. The buffer solution specifically may have a pH of about 3.0 to 6.0, preferably about 3.1 to 4.5, more specific about 3.2 to 4.0, even more specific about 3.3 to 3.6, most specific about 3.5.

25

The present invention furthermore also provides a method of preparing a gelling agent for food products wherein the method comprising the processing steps of: i) providing a viscous gelling agent; and ii) treating the viscous gelling agent with an acidic buffer solution.

30

The invention finally also provides a casing obtained by the method according the present invention. A casing prepared by the method of the present invention has 15 improved strength properties compared to a similar casing material comprising the same viscous gelling agent that is not treated with an acidic buffer solution.

The present invention will be further elucidated on the basis of the non-limitative 5 exemplary embodiment shown in the following figure.

Figure 1 shows a flowchart schematically describing the method of the present invention.

10 Figure 1 shows a flowchart schematically describing the method of the present invention. In this schematic overview gelling agent is treated with acidic buffer solution. The regulator that is connected to the automated pH-measuring device regulates the amount of acidic buffer solution added to the gelling agent. The automated pH-measuring device is subsequently connected to the acidic buffer solution, gelling 15 agent and food dough. Based on the ionic strength differences between the gelling agent and the food dough, the amount of acidic buffer solution added to the gelling agent is adjusted automatically by the automated pH-measuring device. The treated gelling agent is mixed with the food dough directly and extruded to form a food strand and/or the treated gelling agent is formed into a casing and co-extruded with the food dough to 20 form a food strand at least partially coated with the gelling agent.

The present invention will now be further illustrated using the non-limitative examples below.

25 Examples Example 1 A 250 mM, pH 3.5 buffer solution was prepared containing 38.93 g/kg citric acid and 30 19.03 g/kg sodium citrate and 892.04 g water. This mixture was mixed with a high speed blender until both citric acid and sodium citrate was dissolved. 50 g/kg of Sodium alginate was added to the well mixed solution of water, citric acid and sodium citrate. This mixture was mixed for about 5 minutes to hydrate the sodium alginate. After 16 mixing the created gel is vacuumed to extract the enclosed air as much as possible, to improve extrudability. The produced gel was subsequently co-extruded with food dough to produce coated food strand.

5 Example 2 A 250 mM, pH 3.5 buffer solution was prepared containing 38.93 g/kg citric acid and 19.03 g/kg sodium citrate and 877.04 g water. This mixture was mixed with a high speed blender until both citric acid and sodium citrate was dissolved. 50 g/kg Collagen 10 fibers are added and mixed until the collagen fibers were completely swelled. 15 g/kg of Sodium alginate was added to the well mixed solution of water, citric acid, sodium citrate and collagen fibers. This mixture was mixed for about 5 minutes to hydrate the sodium alginate. After mixing the created gel is vacuumed to extract the enclosed air as much as possible, to improve extrudability. The produced gel was subsequently co-15 extruded with food dough to produce coated food strand.

Figures 2 to 4 illustrate the differences in strength using casing gel material without treated with the acidic buffer solution of the present invention comprising mead dough free of phosphate (figure 2) and comprising meat dough comprising 0.5% phosphate 20 (figure 3) compared to casing gel material according to the present invention (figure 4).

The method of the present invention results in a stronger food product which is more stable over time compared to food products comprising a prior art casing method.

Claims

A method for preparing food products by processing food particles with a gelling agent, comprising the processing steps: a) providing food particles; b) providing a viscous gelling agent; c) treating the viscous gelling agent with an acidic buffer solution; and d) contacting the food particles with the viscous gelling agent.

2. A method according to claim 1, characterized in that the viscous gelling agent comprises polysaccharides.

Method according to claim 1 or 2, characterized in that the viscous gelling agent comprises protein.

Method according to one of the preceding claims, characterized in that the polysaccharides comprise alginate, methyl cellulose, pectin or combinations thereof.

Method according to claim 3 or 4, characterized in that the protein comprises collagen, milk protein or combinations thereof. 25

A method according to any one of the preceding claims, characterized in that the acidic buffer solution has a pH of about 3.0 to 6.0, preferably about 3.1 to 4.5, more preferably about 3.2 to 4 , Even more preferably about 3.3 to 3.6, most preferably about 3.5. 30

Method according to one of the preceding claims, characterized in that the acidic buffer solution has a total concentration of buffering agents of approximately 50 to 500 mM, preferably approximately 100 to 400 mM, more preferably approximately 200 to 300 mM, with the largest preferably about 250 mM.

A method according to claim 7, characterized in that the buffering agents are selected from citric acid, sodium citrate and / or calcium citrate.

A method according to any one of the preceding claims, characterized in that the acidic buffer solution is formulated into a gel or paste comprising a thickener.

10. Method as claimed in any of the foregoing claims, characterized in that the method further comprises a strengthening step e) wherein the viscous gelling agent is treated with a liquid strengthening agent.

11. A method according to claim 10, characterized in that the liquid reinforcing agent is added to the viscous gelling agent during the time that or after the gelling agent has been brought into contact with the food particles.

A method according to claim 10 or 11, characterized in that the liquid strengthening agent comprises salt solutions selected from sodium salt, potassium salt, calcium salt, magnesium salt and combinations thereof. 20

A method according to any one of claims 10 to 12, characterized in that the liquid reinforcing agent comprises calcium salt in a concentration of about 0.001 to 15% by weight, preferably about 0.01 to 10% by weight. 25

A method according to any one of claims 10 to 13, characterized in that the liquid reinforcing agent further comprises salts of sodium or potassium.

15. A method according to claim 14, characterized in that the concentration of sodium and / or potassium substantially corresponds to the concentration of sodium and / or potassium in the food particles.

A method according to any one of the preceding claims, characterized in that the method further comprises a stabilization step f), wherein the food product is treated with an acid-stabilizing solution.

A method according to claim 16, characterized in that the acid stabilizing solution has a pH of less than about 3.0, preferably about 2.0 to 2.5.

18. A method according to claim 16 or 17, characterized in that the acid-stabilizing solution comprises citric acid, sulfuric acid, hydrochloric acid or combinations thereof.

A method according to any one of the preceding claims, characterized in that the meat particles are formed into separate food products that are each composed of food particles and gelling agent after step d), step e) and / or step f). 15

The method according to any of the preceding claims, characterized in that the viscous gelling agent comprises about 1.0 to 8.0 weight percent alginate.

21. Method according to one of the preceding claims, characterized in that in the strengthening step e) the liquid strengthening agent and / or in the stabilizing step f) the acid stabilizing solution comprises an enzymatic solution and / or a crosslinker.

22. Method as claimed in any of the foregoing claims, characterized in that the processing of food particles comprises the extrusion of a food dough, preferably a meat dough.

23. Method for preparing food products by means of extrusion according to claim 22, characterized in that during processing step d) the treated viscous gelling agent at least partially encloses the strand of food dough.

Method for preparing food products by means of extrusion according to claim 22 or 23, characterized in that during processing step d) the viscous gelling agent is at least partially mixed with the strand of food dough.

25. Method as claimed in any of the foregoing claims, characterized in that processing food particles comprises dividing food products into portions.

A method according to any one of the preceding claims, characterized in that the processing of food particles comprises the joining of food particles.

A method for preparing food products by combining food particles according to claim 26, characterized in that before or during processing step d) the treated viscous gelling agent binds the food particles.

A method according to any one of the preceding claims, characterized in that the processing of food particles comprises the injection of food particles with the treated viscous gelling agent.

29. Method as claimed in any of the foregoing claims, characterized in that at least one electrical property of the food particles and / or the viscous gelling agent is measured and the results are subsequently used for automated adjustment of the addition properties of the during processing step c) used acid buffer solution.

Method according to one of the preceding claims, characterized in that the mechanical strength of the food particles and / or the viscous gelling agent is measured and the results are subsequently used for automated adjustment of the properties of the acidic buffer solution used during processing step c).

A method according to any one of the preceding claims, characterized in that the food particles are brought into contact with the viscous gelling agent in multiple stages during processing step d). 30

Method according to one of the preceding claims, characterized in that the processing steps a) to d) are consecutive processing steps.

33. A method according to any one of the preceding claims, characterized in that the method further comprises a salting step in which the outside of the food product is treated with an aqueous saline solution.

A method for at least partially dehydrating the casing of a food product, comprising the processing steps: 10 x) providing a food product that is at least partially covered with a viscous gelling agent; y) providing electrodes; and z) electrifying the food product. 15

A method for stabilizing a viscous gelling agent in the method according to any one of claims 1 to 32, characterized in that the method further comprises the salting step according to claim 34.

An apparatus for preparing food products by processing food particles with a gelling agent in accordance with the method of any one of the preceding claims.

An apparatus according to claim 36, characterized in that the apparatus comprises measuring means for automatically measuring electrical properties and / or mechanical strength of the food particles and / or the viscous gelling agent.

38. Device as claimed in claim 36 or 37, characterized in that the device also comprises an intelligent control unit for automatically adjusting the ionic strength of the acidic buffer solution.

A food product obtained by the method according to any one of claims 1 to 35.

Use of a buffer solution for stabilizing a viscous gelling agent in the method according to one of claims 1 to 35, characterized in that the buffer solution has a pH of about 3.0 to 6.0, preferably about 3 , 1 to 4.5, more preferably about 3.2 to 4.0, even more preferably about 3.3 to 3.6, most preferably about 3.5.

41. A method for preparing a gelling agent for food products, comprising the processing steps: i) providing a viscous gelling agent; and ii) treating the viscous gelling agent with an acidic buffer solution.

Food packaging material obtained by the method according to claim 41.