Method for texturising proteins which are alternatives to animal proteins

Abstract

The invention relates to a method for producing or transforming a protein-containing medium, of plant, dairy, animal or microbial origin, characterised in that, during one or more of the phases involved in the production or transformation process in question, the state of the sulfur-containing thiol groups of the medium is controlled or modified by injecting a selected gas or gas mixture having a reducing or oxidising nature that makes it possible to achieve a given action on the groups.

Description

Process for texturizing proteins as alternatives to animal proteins

[0001] The present invention relates to the field of methods for transforming alternative proteins, and in particular, but not exclusively, alternative protein concentrates or isolates to animal proteins, and it is particularly concerned with proteins of plant origin, as well as with methods and devices for manufacturing processed food products based on such alternative proteins.

[0002] The invention is particularly concerned with proteins of plant origin (wheat proteins (glutenins, etc.), soy protein (glycinin)), milk proteins (serum proteins, alpha-lactalbumin and beta-lactoglobulin), and animal proteins (egg globulins).

[0003] Proteins are made up of a set of amino acids, including cysteines. These contain sulfur atoms in the form of thiol / sulfhydryl (-SH) groups. Through oxidation, these thiol groups can form disulfide (SS) bonds. The molecule resulting from the bonding of two cysteines is cystine. A disulfide bond is therefore a bond between two sulfur atoms in a protein and contributes to the stabilization of its tertiary or quaternary structure. If disulfide bonds form within a protein, certain processes rely on the formation of disulfide bonds between two proteins to create a network.

[0004] For example, in breadmaking, during kneading, and in the presence of water, the protein chains of the flour (gliadins and glutenins) gradually unwind and align. The thiol groups of the different proteins are made accessible, and will react two by two and bind by a covalent bond between their sulfur atoms to form disulfide bridges. This forms a protein complex called gluten which will later be able to contain the gas formed during the rising of the bread, and which is therefore at the origin of the structure of the bread.

[0005] The present invention therefore relates to the methods of producing or transforming a protein medium, whether this medium is of plant, dairy, animal or even microbial origin, this medium being able to be used in various products, and in particular food, pharmaceutical, cosmetic, hygiene products, etc.

[0006] As will be seen in more detail below, the method of the invention aims to enable, during one or more of the phases occurring during the production or transformation process, the state of the sulfur thiol groups in the medium to be controlled or modified by the injection of a chosen gas or gas mixture, the reducing or oxidizing nature of which enables a given action to be obtained on said groups.

[0007] It is therefore desired, within the framework of the present invention, to be able to propose a technical solution making it possible to control the state of the sulfur groups (-SH / SS) in different applications requiring it and thus control the formation of a protein network, by using the oxidizing and reducing characteristics of certain chosen gases.

[0008] Among the various transformation processes using such proteins, we can cite: Thickening processes; Texturing reinforcement processes; 3D printing; Controlling the viscosity of a liquid before its implementation (to facilitate transport, pumpability, etc.); or even The creation of new textures.

[0009] The present invention relates in particular to the following products: matrices based on vegetable proteins, insect proteins or proteins of unicellular origin intended to produce meat analogues; yogurts (cow's milk or vegetable milks) and other dairy products; bakery products.

[0010] One of the objectives of the present invention is to propose a technical solution making it possible to control the state of the sulfur groups (-SH / SS) in different applications requiring it, and thus to control the formation of a protein network, by using the oxidizing and reducing characteristics of certain chosen gases.

[0011] The gases envisaged in the context of the present invention are in particular: oxygen, an oxidizing gas, which makes it possible to increase the redox potential of a medium, and which promotes the oxidation of thiols into disulfide bridges (air or enriched air can also fulfill this role); hydrogen, a reducing gas, which promotes the reduced state (-SH) of sulfur molecules, which can bond to form an SS bridge when the medium becomes oxidizing again; nitrogen, although neutral from the point of view of redox potential, can be used to eliminate oxygen from a liquid, pasty or gaseous medium; it therefore indirectly makes it possible to reduce the redox potential of a medium, and to promote the reduced state (-SH) of thiol groups (argon can also fulfill this role).

[0012] And we can also consider within the framework of the present invention mixtures with CO2 (O2 / CO2, N2 / CO2...) with the aim of being able to play on the pH which also plays a role on the state of the proteins.

[0013] The following gases and mixtures may therefore be considered in the context of the invention, in particular, included in the group formed by: oxygen, air or oxygen-enriched air, an oxidizing gas which makes it possible to increase the redox potential of a medium, and which promotes the oxidation of thiols into disulfide bridges; hydrogen, and gas mixtures comprising hydrogen, a reducing gas, which promotes the reduced state (-SH) of sulfur molecules, which can bond to form an SS bridge when the medium becomes oxidizing again; nitrogen or argon or their mixtures, which can be used to eliminate oxygen from a liquid, pasty or gaseous medium and which therefore indirectly makes it possible to reduce the redox potential of a medium, and to promote the reduced state (-SH) of thiol groups; gas mixtures comprising CO2 such as: O2 / CO2, O2 / N2 / CO2 such as oxygen-enriched air and containing CO2, N2 / CO2, and Ar / CO2. Gas mixtures containing nitrogen and / or argon and / or hydrogen.

[0014] When using oxygen-enriched air, more oxygen dissolves in the medium to be treated than when using simple air. This increases the kinetics and intensity of oxidation reactions. Furthermore, the use of oxidizing / reducing gases is preferable to chemical additives because it is reversible. One gas can easily be replaced by another, thus switching a medium from one redox state to another.

[0015] Furthermore, we know that, in comparison, additives are subject to very strict regulatory constraints; they must appear on the labelling of the finished product; they are not always sensorially neutral, and they can present (like sulphites, for example) risks of intolerance and allergy, without forgetting that they convey a negative image to the public, far from naturalness.

[0016] As described above, it is desired, within the framework of the present invention, to be able to propose a technical solution making it possible to control the state of the sulfur groups (-SH / SS) in different applications requiring it and thus to control the formation of a protein network, this by the use of the oxidizing and reducing characteristics of certain chosen gases.

[0017] Let us then exemplify in the following different cases of implementation of the invention.

[0018] Let us examine in particular a first case of "thickening" operation, where a medium A must be thickened. A liquid B containing proteins including cysteines is bubbled with a reducing gas, or with nitrogen to expel the oxygen, it is then heated in order to denature the proteins which unfold and expose their thiol groups because in a reducing medium. Liquid B is then added to liquid A under oxidizing conditions (by the use of oxygen for example) so that disulfide bridges form between the proteins, thus creating a network which eventually traps the other components of media A and B.

[0019] Liquid A can be any medium to be thickened, but which contains little or no protein, some of which will depend on the redox potential, for example a food or body cream, or for example a soup to be enriched with protein.

[0020] Liquid B is, for example, a suspension or solution of proteins whose state, structure, depends on the redox potential.

[0021] Depending on the industrial application considered, it is possible to create a desired texture without adding additives (such as thickeners such as gums, starches, etc.).

[0022] The addition of a reducing or neutral gas such as H2 or N2 lowers the redox potential of the medium (protein B) and thus promotes the reduced state (-SH) of the sulfur molecules, which can bind to form an SS bridge when the medium becomes oxidizing again.

[0023] Let us exemplify in the following a second case of implementation of the invention, to produce a product, for example a food product, by 3D printing.

[0024] Using nitrogen (to expel oxygen) and / or hydrogen, a protein-based matrix is ​​heated under reducing conditions. It then feeds the nozzle(s) of a 3D printer to create a food according to construction procedures known to those skilled in the art. Once the nozzle has been placed in an oxygen-rich environment (for example, by placing the printer in an oxygen-filled enclosure), the thiol groups of the matrix oxidize and form disulfide bonds with the proteins of the surface layer of the product being formed, onto which the nozzle deposits the product. This creates a protein network and ensures good stability of the product thus produced.

[0025] The appendix illustrates such a 3D printing installation where we distinguish: A deposition chamber 1 which is under an oxidizing atmosphere, for example under oxygen; A working support 2; A heating nozzle 3; A line 4 in which the reduced liquid matrix circulates (arrival of a protein-based fluid matrix which has been heated under reducing conditions and which feeds the nozzle 3 (it will be noted that the nozzle 3 can be a bi-fluid nozzle jointly injecting the protein fluid and an oxidizing gas)); A pump 5; 6: element constructed by 3D printing.

[0026] Let us exemplify in the following a third case of implementation of the invention, to control the viscosity of a liquid before its implementation.

[0027] In some manufacturing processes, we want to maintain a low viscosity, which can present several advantages for the industrial production site: facilitating transport, pumpability, cleaning, limiting losses during transfers, etc.

[0028] When we want to maintain a low viscosity of a matrix containing partially or totally denatured proteins whose thiol groups are exposed (denaturation is the loss of the native (original) structure of the protein by the action of a parameter such as for example temperature, pressure, a chemical compound… it can be reversible or not, in general it is described as a deployment of the structure, with loss of the quaternary and ternary structures, and in extreme cases the secondary structure), we propose to use nitrogen and / or hydrogen in order to lower the redox potential of this matrix and avoid the formation of disulfide bridges which would create a structure increasing the viscosity.

[0029] It is then possible to switch, at the desired point in the process, to an oxidizing environment to create a protein network and therefore structure the product.

[0030] As an illustration, the following phases can be exemplified: Phase 1: formulation of the liquid matrix, deoxygenated by nitrogen flushing or treated with hydrogen. Phase 2: heat treatment of the matrix. Phase 3: transfer / transport / transfer of the medium according to the needs of the industrial process. Phase 4: contacting the medium with an oxidizing gas (by bubbling, or mixing under an oxidizing atmosphere, etc.)

[0031] The desired moment mentioned above is typically the moment when the manufacturer has finished transferring their product and wishes to give the product its final texture.

[0032] The present invention then relates to a process for producing or transforming a protein medium, of plant, dairy, animal or even microbial origin, characterized in that during one or more of the phases occurring during the production or transformation process in question, the state of the sulfur thiol groups of the medium is controlled or modified by the injection of a chosen gas or gas mixture, the reducing or oxidizing nature of which allows a given action to be obtained on said groups.

[0033] According to one of the modes of implementation of the invention, the production or transformation process considered uses a medium or a matrix which is, by its very composition, already naturally reducing.

[0034] For example, in these cases we find: matrices naturally or not containing reducing molecules such as vitamin C or other antioxidants; a matrix which has been deoxygenated by a vacuum process; milk or other liquid whose redox potential has been lowered by microbial activity, for example by lactic acid bacteria;

[0035] .etc…..

[0036] The present invention then relates to a process for producing or transforming a protein medium, of plant, dairy, animal or even microbial origin, characterized in that during one or more of the phases occurring during the production or transformation process in question, the state of the sulfur thiol groups of the medium is controlled or modified by the injection of a chosen gas or gas mixture, the reducing or oxidizing nature of which allows a given action to be obtained on said groups.

[0037] According to one of the embodiments of the invention, the method is one of the transformation methods of the group formed by: Thickening methods; Texturing reinforcement methods; 3D printing; Control of the viscosity of a liquid before its implementation, to facilitate transport, pumpability, etc.; Creation of new textures.

[0038] According to one of the embodiments of the invention, the gas or gas mixture used is included in the group formed by: oxygen, air or oxygen-enriched air, an oxidizing gas which makes it possible to increase the redox potential of a medium, and which promotes the oxidation of thiols into disulfide bridges; hydrogen, and gas mixtures comprising hydrogen, a reducing gas, which promotes the reduced state (-SH) of sulfur molecules, which can bond to form an SS bridge when the medium becomes oxidizing again; nitrogen or argon or their mixtures, which can be used to eliminate oxygen from a liquid, pasty or gaseous medium and which therefore indirectly makes it possible to reduce the redox potential of a medium, and to promote the reduced state (-SH) of thiol groups; gas mixtures comprising CO2 such as: O2 / CO2, O2 / N2 / CO2 such as oxygen-enriched air and containing CO2, N2 / CO2, and Ar / CO2. Gas mixtures containing nitrogen and / or argon and / or hydrogen.

[0039] According to the invention, reducing gases are to be understood as gases which do not contain oxygen, and oxidizing gases as gases containing oxygen.

[0040] The mixtures mentioned above, containing CO2, are very useful for adjusting the pH downwards if necessary.

[0041] According to one of the embodiments of the invention, the method is a method for thickening a medium, where:A medium A is provided which is to be thickened;A liquid B is provided containing proteins comprising cysteines;A step of bubbling liquid B is carried out using a reducing gas such as hydrogen or using nitrogen to expel oxygen therefrom;A step of heating this liquid B is carried out in order to denature the proteins which unfold and expose their thiol groups in such a reducing medium;This liquid B is added to liquid A (or liquid A to liquid B) under oxidizing conditions, for example in the presence of oxygen, in order to allow disulfide bridges to form between the proteins, thus creating a network which can, if necessary, trap other components of media A and B.

[0042] According to one of the embodiments of the invention, the medium A to be thickened is a food cream or a body cream, or a soup to be enriched with proteins and in that the liquid B is a suspension or solution of proteins whose state, and structure, depends on the redox potential.

[0043] According to one of the embodiments of the invention, the method is a method for producing a food product by 3D printing, where: A protein-based matrix is ​​heated under an atmosphere of nitrogen and / or argon and / or hydrogen or mixtures thereof, which atmosphere may also contain CO2; This heated matrix is ​​fed to one or more nozzles of a 3D printer capable of constructing said product; The nozzle is placed in an oxidizing atmosphere containing oxygen, for example under air or under pure oxygen, for example by the fact that the printer is placed in an enclosure containing oxygen; The product is deposited using the nozzle on a support;

[0044] and wherein said nozzle(s) are configured to inject the protein matrix alone or to jointly inject the protein matrix and an oxidizing gas.

[0045] The matrix has preferably, prior to heating, been deoxygenated using a reducing gas.

[0046] According to one of the embodiments of the invention, the method is a method for controlling the viscosity of a liquid protein matrix before its implementation in an overall production process, for example to improve its pumpability, or to limit losses during transfers, etc., where the following measures are implemented: Nitrogen and / or argon and / or hydrogen, or one of their mixtures, is implemented in the matrix in order to lower the redox potential of this matrix and avoid the formation of disulfide bridges which would create a structure increasing the viscosity; Subsequently, at a desired time in said overall process, the matrix is ​​brought back into contact with an oxidizing gaseous medium in order to create a protein network and thus structure the targeted product.

[0047] According to one of the embodiments of the invention, the following phases are carried out: A Phase No. 1 comprising the formulation of said liquid matrix, which is deoxygenated by flushing or bubbling with nitrogen and / or argon or treated using hydrogen. A Phase No. 2 where a heat treatment of the matrix is ​​carried out. A Phase No. 3 where the transfer or transport or decanting of said matrix is ​​carried out within said overall process according to the needs of the producing industrial site. A Phase No. 4 where the contact of said matrix with an oxidizing gas such as oxygen is carried out, for example by bubbling, or for example by a mixing action under the atmosphere formed by said oxidizing gas.

[0048] According to one of the embodiments of the invention, the method uses a medium or a matrix which is, by its very composition, already naturally reducing, such as: a matrix naturally or not containing reducing molecules such as for example vitamin C or other antioxidants; a matrix which has been deoxygenated by a vacuum process; milk or other liquid whose redox potential has been lowered by microbial activity, for example by lactic acid bacteria.

Claims

A method for producing or transforming a protein medium (4), of plant, dairy, animal or microbial origin, according to which during one or more of the phases occurring during the production or transformation process in question, the state of the sulfur thiol groups of the medium is controlled or modified by the injection of a chosen gas or gas mixture, the reducing or oxidizing nature of which allows a given action to be obtained on said groups, characterized in that the method is a method for producing a food product (6) by 3D printing, where: A protein-based matrix (4) is heated under an atmosphere of nitrogen and / or argon and / or hydrogen or mixtures thereof, which atmosphere may also contain CO2; This heated matrix is fed to one or more nozzles (3) of a 3D printer capable of constructing said product;The nozzle is placed in an oxidizing atmosphere containing oxygen, for example in air or in pure oxygen, for example by the fact that the printer is placed in an enclosure (1) containing oxygen; The product is deposited using the nozzle on a support (2); and where said nozzle(s) are configured to inject the protein matrix alone or to jointly inject the protein matrix and an oxidizing gas.; Method according to claim 1, characterized in that the matrix has been, prior to heating, deoxygenated using a reducing gas. Method according to claim 1, characterized in that the gas or gas mixture used is included in the group formed by:oxygen, air or oxygen-enriched air, an oxidizing gas which makes it possible to increase the redox potential of a medium, and which promotes the oxidation of thiols into disulfide bridges;hydrogen, and gas mixtures comprising hydrogen, a reducing gas, which promotes the reduced state (-SH) of sulfur molecules, which can bond to form an SS bridge when the medium becomes oxidizing again;nitrogen or argon or their mixtures, which can be used to eliminate oxygen from a liquid, pasty or gaseous medium and which therefore indirectly makes it possible to reduce the redox potential of a medium, and to promote the reduced state (-SH) of thiol groups;gas mixtures comprising CO2 such as:O2 / CO2,O2 / N2 / CO2 such as oxygen-enriched air and containing CO2, N2 / CO2, Ar / CO2, H2 / CO2, N2 / H2 / CO2, Ar / H2 / CO2. Gas mixtures containing nitrogen and / or argon and / or hydrogen. Method according to one of the preceding claims, characterized in that it uses a medium or a matrix which is, by its very composition, already naturally reducing, such as: a matrix naturally or not containing reducing molecules such as for example vitamin C or other antioxidants; a matrix which has been deoxygenated by a vacuum process; milk or other liquid whose redox potential has been lowered by microbial activity, for example by lactic acid bacteria.

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