Process for reducing sulphur dioxide

Abstract

The present invention relates to a process for reducing sulphur dioxide in a protein-rich stream. The present inventors have surprisingly found that by treating a protein-rich stream with ozone up to 100% of the present sulphur dioxide in the protein-rich stream is reduced. The present invention also relates to the use of ozone to reduce the sulphur dioxide content in a protein-rich stream.

Description

PT-2118-WO-PCTPROCESS FOR REDUCING SULPHUR DIOXIDECROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of European Application No. 24204724.9, filed October 4, 2024, which is incorporated by reference herein in its entirety.FIELD OF THE INVENTION

[0002] The present invention relates to a process for reducing sulphur dioxide in a protein-rich stream. The present invention further relates to a use of gaseous ozone for reducing sulphur dioxide in a protein-rich stream.BACKGROUND OF THE INVENTION

[0003] For over 100 years, com wet milling has been used to separate corn kernels into products such as starch, protein, fiber and oil. Corn wet milling is a two-stage process that includes a steeping process to soften the corn kernel to facilitate the next wet milling process step that results in purified starch and different co-products, such as oil, fiber and protein. Further com processing methods are now being investigated to further purify the protein coproduct for incorporation into food-grade products, specifically.

[0004] Protein-rich streams derived from typical wet corn milling processes contain high amounts of sulphur dioxide, due to sulfite being added to facilitate effective wet milling of corn. The added sulfite plays two major roles during wet milling of corn: firstly to cleave disulfide bonds in the storage protein matrix thereby loosing protein-starch entrapment to facilitate starch / protein separation; and secondly to control unwanted microbial growth during the entire wet milling process. Consequently, the mill protein stream contains undesired high amounts of sulphur dioxide.

[0005] With a movement towards cleaner food labels, there is a desire to reduce the sulphur dioxide content in these protein-rich streams.

[0006] WO2017 / 165748 Al, WO2017 / 165756 Al, WO2016 / 154441 Al,W02019 / 060179 Al, W02018 / 058150 Al and W02018 / 237030 Al disclose methods to obtain corn protein products.

[0007] However, there remains a need to provide a process for reducing sulphur dioxide in a protein-rich stream.PT-2118-WO-PCT

[0008] It is an object of the present invention to provide a process for reducing sulphur dioxide in a protein-rich stream.

[0009] It is a further object of the present invention to provide a use of gaseous ozone for reducing sulphur dioxide in a protein-rich stream.SUMMARY OF THE INVENTION

[0010] The present invention provides in a first aspect a process for reducing sulphur dioxide in a protein-rich stream comprising(a) Providing a protein-rich stream, wherein the protein-rich stream comprises more than 20 wt.% corn protein on a dry weight basis; and(b) Treating the protein-rich stream with gaseous ozone to afford or obtain a com protein product.

[0011] The present inventors have surprisingly found that by treating a protein-rich stream with ozone up to 100% of the present sulphur dioxide in the protein-rich stream is reduced, as shown in the appended examples.

[0012] Without wishing to be bound by any theory the present inventors believe that the ozone oxidizes the sulphur dioxide to sulphate.

[0013] Advantageously, the protein-rich stream is treated with a gas to remove the sulphur dioxide and not with an aqueous solution containing an oxidant, which eliminates the need for additional water to treat the protein-rich stream.

[0014] The present invention also relates to a use of ozone to reduce the sulphur dioxide content in a protein-rich stream.

[0015] Representative features of the invention are set out in the following clauses, which stand alone or may be combined, in any combination, with one or more features disclosed in the text and / or drawings of the specification.1. A process for reducing sulphur dioxide in a protein-rich stream comprising(a) Providing a protein-rich stream, preferably derived from a wet com milling operation, wherein the protein-rich stream comprises more than 20% com protein on a dry weight basis; and(b) Treating the protein-rich stream with gaseous ozone, wherein the gaseous ozone comprises ozone in an amount between 1 and 200 ppm relative to the gaseous ozonePT-2118-WO-PCT to obtain a corn protein product.2. Process according to clause 1, wherein the protein-rich stream has a sulphur dioxide content of at least 50 ppm or at least 100 ppm or at least 200 ppm, relative to the protein-rich stream.3. Process according to clause 1 or 2, wherein the amount of ozone in the gaseous ozone is between 5 and 150 ppm, preferably between 8 and 100 ppm, more preferably between 10 and 50 ppm relative to the gaseous ozone.4. Process according to any one of the previous clauses, wherein treating the proteinrich stream with gaseous ozone is between 5 minutes and 2 hours, preferably between 15 minutes and 1.5 hour, more preferably between 25 minutes and 1.5 hour.5. Process according to any one of the previous clauses, wherein the corn protein product has a sulphur dioxide content of less than 40 ppm, preferably less than 20 ppm, more preferably less than 10 ppm, relative to the com protein product.6. Process according to any one of the previous clauses, wherein at least 75% of the amount of sulphur dioxide present in the protein-rich stream is removed after step b), preferably at least 85%, more preferably at least 95%, most preferably at least 99%.7. Process according to any one of the previous clauses, wherein the protein-rich stream is selected from the group consisting of corn gluten meal, germ meal, corn gluten cake, corn protein concentrate, corn protein isolate and any combination thereof.8. Process according to any one of the previous clauses, wherein the protein-rich stream comprises between 20 wt.% and 50 wt.% corn protein on a dry weight basis, or between 50 wt.% and 98 wt.% corn protein on a dry weight basis.9. Process according to any one of the previous clauses, wherein the protein-richPT-2118-WO-PCT stream comprises at least 80 wt.% com protein on a dry weight basis.10. Process according to any one of the previous clauses, wherein the protein-rich stream comprises water in amount of less than 85 wt.% relative to the protein-rich stream, preferably less than 70 wt.%, more preferably less than 60 wt.%.11. Process according to any one of clauses 1-9, wherein the protein-rich stream comprises water between 1 and 10 wt.%, relative to the protein-rich stream, more preferably between 1 and 5 wt.%, most preferably between 2 and 4 wt.% relative to the protein-rich stream.12. Process according to any one of the previous clauses, wherein the ozone-treated protein-rich stream obtained during step (b) is subjected to washing the protein-rich stream with a solvent comprising water and a water-miscible solvent to obtain the com protein product.13. Process according to clause 12, wherein the washed ozone-treated proteincontaining stream is dried before obtaining the corn protein product.14. Use of gaseous ozone to reduce the sulphur dioxide content in a protein-rich stream, preferably derived from a wet corn milling operation, wherein the amount of ozone is between 1 and 200 ppm relative to the gaseous ozone.15. The corn protein product obtainable by the process according to any one of clauses 1-13.16. Use of the corn protein product according to clause 15 for reducing sulphur dioxide in a protein-rich stream for feeding domestic animals.DETAILED DESCRIPTION

[0016] The term "comprising", as used herein and in the claims, should not be interpreted as being restricted to the means listed thereafter; it does not exclude other elements or steps. It needs to be interpreted as specifying the presence of the stated features, integers,PT-2118-WO-PCT steps or components as referred to, but does not preclude the presence or addition of one or more other features, integers, steps or components, or groups thereof. Thus, the scope of the expression "a composition comprising components A and B" should not be limited to compositions consisting only of components A and B. It means that with respect to the present invention, the only relevant components of the composition are A and B. Accordingly, the terms "comprising" and "including" encompass the more restrictive terms "consisting essentially of' and "consisting of'.Process

[0017] In a first aspect the invention provides a process for reducing sulphur dioxide in a protein-rich stream comprising(a) Providing a protein-rich stream, wherein the protein-rich stream comprises more than 20 wt.% com protein on a dry weight basis; and(b) Treating the protein-rich stream with gaseous ozone, wherein the gaseous ozone comprises ozone in an amount between 1 and 200 ppm relative to the gaseous ozone to obtain a com protein product.Step (a)

[0018] Preferably the protein-rich stream provided in step (a) is derived from a wet com milling operation. The protein-rich stream may be, for example but not limited to, corn germ meal, com gluten meal, corn gluten cake, com protein concentrate (for example Cargill Empyreal®), or corn protein isolate. However, these protein-rich streams are rich in sulphur dioxide originating from the steeping solution in the wet-milling process. These protein-rich streams may typically contain a sulphur dioxide content in the range of at least 50 ppm, or of at least 100 ppm, or at least 150 ppm, or at least 200 ppm or at least 300 ppm, relative to the protein-rich stream. The protein-rich stream may have a sulphur dioxide content of at most 1000 ppm, or at most 500 ppm, or at most 400 ppm, or at most 300 ppm relative to the protein-rich stream. The protein-rich stream may have a sulphur dioxide content between 50 and 1000 ppm, or between 150 and 500 ppm, or between 200 and 300 ppm relative to the protein-rich stream. As appreciated by the skilled person, in the protein-rich stream, the presence of sulfur dioxide is to be in a state of chemical equilibrium with bisulfite and sulfite ions. Hence, in the present invention a reduction of sulfur dioxide is to be interpreted as a reduction of the sum of sulphurPT-2118-WO-PCT dioxide, bisulfite and sulfite, measured as the amount of sulphur dioxide present in the proteinrich stream.

[0019] Sulphur dioxide content of the protein-rich stream or the corn protein product can be measured according to the method AO AC 962.16.

[0020] Further, the protein-rich stream typically comprises more than 20 wt.% corn protein, or more than 50 wt.% com protein, or more than 80 wt.% corn protein, or more than 85 wt.% corn protein, or more than 95 wt.% com protein, or more than 98 wt.% corn protein on a dry weight basis. The protein-rich stream comprises between 20 and 98 wt.% com protein, or between 20 and 50 wt.%, or between 50 and 98 wt.%, or between 85 and 98 wt.%, or between 95 and 98 wt.% corn protein on a dry weight basis.

[0021] The corn protein content is measured according to the Kjeldahl method. The Kjeldahl method is a well-known method to analyze protein content, such as corn protein content.

[0022] The protein-rich stream may be selected from the group consisting of com gluten meal, germ meal, corn gluten cake, corn protein concentrate, com protein isolate and any combination thereof.

[0023] Hence, the type of protein-rich stream defines the com protein content. Accordingly, the corn gluten meal comprises between 55 and 75 wt.% com protein on a dry weight basis, preferably between 60 and 70 wt.% com protein on a dry weight basis. The germ meal comprises between 20 and 30 wt.% corn protein on a dry weight basis. The corn gluten cake comprises between 55 and 75 wt.% corn protein on a dry weight basis, preferably between 60 and 70 wt.%. The com protein concentrate comprises between 70 and 85 wt.% corn protein on a dry weight basis, preferably between 75 and 82 wt.% com protein on a dry weight basis. The corn protein isolate comprises between 85 and 94 wt.% com protein on a dry weight basis, preferably between 85 and 92 wt.%.

[0024] A typical process for producing a corn protein concentrate starts with a corn gluten meal or a com gluten cake typically comprising at least about 55 wt.% com protein, preferably at least 65 wt.% com protein, on a dry basis. In most aspects, the starch in the corn gluten meal remains intact and does not undergo a destarching enzymatic hydrolysis process. Similarly, protein structure in the corn gluten meal or the com gluten cake remains intact, in most aspects, and does not undergo a denaturation / coagulation process under heat conditions. The corn gluten meal or the corn gluten cake may then be washed with a water-miscible solvent.PT-2118-WO-PCTThe water-miscible solvent may be ethanol, ethyl acetate, isopropanol or any combination thereof. Preferably, the water-miscible solvent may be an ethanol-containing or isopropanolcontaining solvent in concentrations ranging from 85 wt.% to 99.5 wt.%, preferably 85 wt.% to 98 wt.% (ethanol or isopropanol), and more preferably in concentrations ranging from 85 wt.% to 95 wt.% (ethanol or isopropanol). The remainder of the water-miscible solvent may be water, so that the water-miscible solvent may comprise an ethanol-containing or isopropanolcontaining solvent in concentrations ranging from 85 wt.% to 99.5 wt.% and water in a concentration from 0.5 wt.% and 15 wt.% water. A series of solvent washing steps may be performed to remove non-protein, non-starch components. Preferably, there are no more than six solvent washing steps. The solvent washes described herein were found to remove many nonprotein components (pigments, organic acids, oils, sulfites, etc.) from the starting corn gluten meal, thus enhancing the recovery of the corn protein concentrate as described in more detail below. Both com gluten meal and the solvent may be introduced in a mixing tank and vigorously mixed for about 15 minutes. To reduce the amount of non-protein, non-starch components contained in the mixture, the mixture goes through an extraction and filtration step. Such extraction may be carried out using a batch stir tank, continuous stir tank reactor or by percolation or immersion extraction. Filtration may be carried out using a Buchner funnel to filter out the non-protein, non-starch component-containing solvent and maintain the protein stream. However, it shall also be understood that, while filtration is used in an aspect of this process, other separation techniques such as drainage, percolation, centrifugation, or decanting may be utilized to achieve the separation of the non-protein, non-starch component-containing solvent from the protein-containing stream. The protein-containing stream undergoes another solvent washing, extraction and filtration step and, in preferred aspects, yet another solvent washing, extraction and filtration step therefore achieving three solvent washing steps. This solvent washing step is repeated once more before the protein-containing stream is dried in a desolventizer before recovering the corn protein concentrate. A goal of the solvent washing process described above is to concentrate the com protein-starch composition by removal of other non-protein components. The protein structure in the com gluten remains intact, in most aspects, and does not undergo a denaturation / coagulation process under heat conditions.

[0025] A typical process for producing a corn protein isolate starts with a corn gluten material. The com gluten material may be destarched. "Destarched" refers to the starting com gluten material having a residual insoluble starch solids in the range from about 0.1 to 3.0 wt.%PT-2118-WO-PCT on dry basis, as measured by Ewers Polarimetric method JSO 10520: 1997. However, if a corn gluten material is not destarched, the com gluten material may undergo enzyme or chemical hydrolysis and a subsequent separation step to hydrolyze and remove, respectively, the majority of starch components contained in the com gluten material. The starting destarched com gluten material may then be washed with a water-miscible solvent. The concentration of the water- miscible solvent may range from about 75 to about 100 wt.%-; or from about 85 to 100 wt.%. The water-miscible solvent may be an ethanol-containing or isopropanol-containing solvent, or mixtures thereof: in concentrations of about 75 to 95 wt%, or from about 85 to 95 wt.%, or about 90 wt.%. A series of solvent washing steps may be performed. The solvent washes described herein were found to remove many non-protein components (pigments, mycotoxins, sugars, organic acids, oils, etc,) from the starting corn gluten material. The destarched corn gluten material and the solvent may be mixed in a mixing tank for about 15 minutes and then sent to a Buchner funnel to filter out the non-protein component-containing solvent and main the protein-enriched stream. The extraction may also be carried out by a continuous stir tank reactor or by percolation or immersion extraction. It shall also be understood that while filtration is used in an aspect of this process, other separation techniques, such as centrifugation or decanting, may be utilized to achieve the separation of the non-protein component-containing solvent from the protein-enriched stream. It shall be understood that the destarched corn gluten material may contain 30-60 wt.% moisture and the amount of ethanol introduced would be adjusted accordingly to achieve the desired ethanol concentration in the extraction tank. That protein-enriched stream may then be introduced to a 90 wt.% ethanol-containing solvent and mixed in a mixing tank for another 15 minutes before the non-protein component-containing solvent is removed from the protein-enriched stream using filtration yet again, This solvent washing step may be repeated once more before the protein-enriched stream is air dried for about 60 minutes and subsequently dried in a convection oven at about 65 °C for about 60 to 120 minutes before recovering the com protein isolate product. A minimum of three solvent washing steps at this solvent-to-solids ratio may be performed in the process to obtain a corn protein isolate product. To reduce the amount of fresh solvent used in the process, the process can be operated as a counter-current extraction.

[0026] Preferably, the protein-rich stream comprises water in an amount of less than 85 wt.%, relative to the protein-rich stream, more preferably less than 80 wt.%, even more preferably less than 70 wt.%, even more preferably less than 65 wt.%, even more preferablyPT-2118-WO-PCT less than 60 wt.%, most preferably less than 55 wt.% relative to the protein-rich stream. Preferably, the protein-rich stream comprises water in an amount of more than 1 wt.%, relative to the protein-rich stream, more preferably more than 2 wt.%, most preferably more than 3 wt.% relative to the protein-rich stream. Preferably, the protein-rich stream comprises water in an amount between 1 and 85 wt.%, relative to the protein-rich stream, more preferably between 2 and 80 wt.%, most preferably between 3 and 70 wt.% relative to the protein-rich stream. More preferably, the protein-rich stream comprises water in an amount between 1 and 10 wt.%, relative to the protein-rich stream, more preferably between 1 and 5 wt.%, most preferably between 2 and 4 wt.% relative to the protein-rich stream.

[0027] Preferably, the protein-rich stream comprises water in an amount of less than 99 wt.%, relative to the protein-rich stream, more preferably less than 95 wt.%, relative to the protein-rich stream.

[0028] The water content can be measured by method TS EN ISO 6540.

[0029] The present inventors have demonstrated that the water content of the proteinrich stream defines the effectiveness of the ozone treatment. Protein-rich streams containing high amounts of water are less effectively treated with the gaseous ozone.

[0030] Hence, more preferably the protein-rich stream comprises- between 20 and 98 wt.% corn protein, or between 50 and 98 wt.%, or between 85 and 98 wt.%, or between 95 and 98 wt.% com protein on a dry weight basis; and- water in an amount between 1 and 80 wt.%, relative to the protein-rich stream, or between 1 and 50 wt.%, most preferably between 1 and 10 wt.% relative to the proteinrich stream.

[0031] Moreover, the protein-rich stream may comprise from 0.01 wt.% to 30 wt.%, or from 0.05 wt.% to 25 wt.%, or from 0.1 wt.% to 20 wt.%, or from 1 wt.% to 15 wt.% of starch on a dry weight basis. The amount of starch is measured according to method TS EN ISO 10520.Step (b)

[0032] Preferably, the protein-rich stream is treated with gaseous ozone, wherein the gaseous ozone comprises ozone in amount of at least 5 ppm relative to the gaseous ozone, more preferably at least 8 ppm, most preferably at least 10 ppm. Preferably the gaseous ozone comprises ozone in amount of at most 200 ppm relative to the gaseous ozone, more preferablyPT-2118-WO-PCT at most 100 ppm, most preferably at most 50 ppm. Preferably, the gaseous ozone comprises ozone in an amount between 5 and to 150 ppm relative to the gaseous ozone, preferably between 8 and 100 ppm, more preferably between 10 and 50 ppm.

[0033] In step (b) the protein-rich stream is treated in order to remove sulphur dioxide down to levels acceptable for human consumption z.e., below 40 ppm. Below 40 ppm sulphur dioxide is generally considered to be safe. However, some people are sensitive to it and may develop allergic reactions, such as asthma. Thus, sulphur dioxide levels below 10 ppm are preferred by many food manufacturers.

[0034] It was surprisingly found that treatment of the protein-rich stream with the gaseous ozone results in reducing the sulphur dioxide content of protein-rich stream down to acceptable levels less than 40 ppm, preferably less than 30 ppm, more preferably less than 20 ppm, even more preferably less than 15 ppm, most preferably less than 10 ppm relative to the com protein product. The sulphur dioxide content of the protein rich stream may even be less than 5 ppm relative to the corn protein product, preferably less than 3 ppm, more preferably less than 1 ppm. Most preferably the com protein product is substantially free of sulphur dioxide. By "substantially free" it is meant herein that sulphur dioxide is below the detection limits of the measurement method.

[0035] As appreciated by the skilled person at least 75% of the amount of sulphur dioxide present in the protein-rich stream is removed, or worded differently oxidized to e.g. sulphate, preferably at least 80%, more preferably at least 85%, even more preferably at least 90%, even more preferably at least 95%, even more preferably at least 99%, most preferably substantially all or 100% of the sulphur dioxide is removed. By "substantially all" it is meant herein that sulphur dioxide is below the detection limits of the measurement method.

[0036] The protein-rich stream may be treated with the gaseous ozone as defined herein. The protein-rich stream may be placed in a chamber, preferably an ozone chamber, wherein the gaseous ozone can be supplied to. The gaseous ozone is generated with a gaseous ozone production equipment. The present invention is not limited to a specific gaseous ozone production equipment and any commercially available gaseous ozone production equipment can be used. The concentration of the ozone in the gaseous ozone can be adjusted with the gaseous ozone production equipment.

[0037] Preferably, the protein-rich stream is treated with the gaseous ozone for at least 5 minutes, preferably at least 15 minutes, more preferably at least 20 minutes, even morePT-2118-WO-PCT preferably at least 25 minutes, most preferably at least 30 minutes. Preferably, the protein-rich stream is treated with the gaseous ozone for at most 2.5 hours, preferably at most 2 hours, more preferably at most 1.5 hour. Preferably, the protein-rich stream is treated with the gaseous ozone for between 5 minutes and 2.5 hours, preferably between 15 minutes and 2 hours, more preferably between 25 minutes and 1.5 hour.

[0038] More preferably, the protein-rich stream in step (b) is treated with the gaseous ozone, wherein- the gaseous ozone comprises ozone in an amount between 5 and to 150 ppm relative to the gaseous ozone, preferably between 8 and 100 ppm, more preferably between 10 and 50 ppm; and- the protein-rich stream is treated with the gaseous ozone for between 5 minutes and 2.5 hours, preferably between 15 minutes and 2 hours, more preferably between 25 minutes and 1.5 hour.

[0039] The treatment of the protein-rich stream in step (b) may occur at a temperature between 10 and 40 °C, preferably between 15 and 35 °C, more preferably between 20 and 30 °C. As appreciated by the skilled person no additional heating step is needed to remove the sulphur dioxide with the gaseous ozone from the protein-rich stream.

[0040] As appreciated by the skilled person the process as defined in the first aspect of the invention, in particular the protein-rich stream treated with gaseous ozone, results in the com protein product. Hence, the corn protein product may be selected from the group consisting of corn gluten meal, germ meal, corn gluten cake, corn protein concentrate, corn protein isolate and any combination thereof. Since, the protein structure during the ozone treatment, in most aspect, remains intact, and does not undergo a denatured on / coagulati on process, the protein content defined under step (a) applies mutatis mutandis to the protein content of the com protein product. Hence, the com protein product comprises more than 20% corn protein, or more than 50% corn protein, or more than 85% corn protein, or more than 95 wt.% corn protein, or more than 98 wt.% corn protein on a dry weight basis. The corn protein product comprises between 20 and 98 wt.% corn protein, or between 50 and 98 wt.%, or between 85 and 98 wt.%, or between 95 and 98 wt.% corn protein on a dry weight basis.

[0041] The com protein product preferably comprises water in an amount of less than 85 wt.%, relative to the corn protein product, even more preferably less than 75 wt.%, even more preferably less than 65 wt.%, even more preferably less than 60 wt.%, most preferablyPT-2118-WO-PCT less than 55 wt.% relative to the com protein product. Preferably, the corn protein product preferably comprises water in an amount of less than 99 wt.%, relative to the corn protein product, more preferably less than 95 wt.%, relative to the com protein product.

[0042] Preferably, the corn protein product comprises water in an amount of more than 1 wt.%, relative to the corn protein product, more preferably more than 2 wt.%, most preferably more than 3 wt.% relative to the corn protein product. Preferably, the corn protein product comprises water in an amount between 1 and 85 wt.%, relative to the com protein product, more preferably between 2 and 80 wt.%, most preferably between 3 and 70 wt.% relative to the corn protein product. More preferably, the corn protein product comprises water in an amount between 1 and 5 wt.%, relative to the com protein product, more preferably between 2 and 5 wt.%, most preferably between 3 and 4 wt.% relative to the corn protein product. Hence, more preferably the corn protein product comprises- between 20 and 98 wt.% corn protein, or between 50 and 98 wt.%, or between 85 and 98 wt.%, or between 95 and 98 wt.% com protein on a dry weight basis; and- water in an amount between 1 and 80 wt.%, relative to the com protein product, or between 1 and 50 wt.%, or between 1 and 5 wt.% relative to the com protein product.

[0043] Furthermore, it is also desirable that the com protein product comprises less than 35% digestible carbohydrate on a dry weight basis. Moreover, the corn protein product may comprise from 0.01 wt.% to 30 wt.%, or from 0.05 wt.% to 25 wt.%, or from 0.1 wt.% to 20 wt.%, or from 1 wt.% to 15 wt.% of starch on a dry weight basis. The amount of starch is measured according to method TS EN ISO 10520.Use

[0044] The present invention provides in a second aspect a use of gaseous ozone to reduce the sulphur dioxide content in a protein-rich stream, wherein the amount of ozone is between 1 and 200 ppm relative to the gaseous ozone. As appreciated by the skilled person all features related to the process for reducing sulphur dioxide in a protein-rich stream as explained under the first aspect of the invention apply mutatis mutandis to the use of the gaseous ozone as defined in the second aspect of the invention. For example, all features related to the amount and identity of the com protein content, the gaseous ozone, the sulphur dioxide amounts and the water content, explained in the context of process for reducing sulphur dioxide are equally applicable to the use of the gaseous ozone.PT-2118-WO-PCTProduct-by-process

[0045] The present invention provides in a third aspect the com protein product obtainable or obtained by the process for reducing sulphur dioxide in a protein-rich stream. As appreciated by the skilled person all features related to the process for reducing sulphur dioxide in a protein-rich stream as explained under the first aspect of the invention and the use of gaseous ozone to reduce the sulphur dioxide content in a protein-rich stream as explained under the second aspect of the invention apply mutatis mutandis to the com protein product obtainable by the process for reducing sulphur dioxide in a protein-rich stream as defined in the third aspect of the invention. For example, all features related to the amount and identity of the corn protein content, the gaseous ozone, the sulphur dioxide amounts and the water content, explained in the context of the first and second aspect of the invention are equally applicable to the corn protein product obtainable by the process for reducing sulphur dioxide in a protein-rich stream.The present invention further provides in a fourth aspect the use of the corn protein product obtainable by the process for reducing sulphur dioxide in a protein-rich stream in feeding domestic animals for economic and companion purposes. The invention described here would allow the manufacture of lower sulphide dioxide containing animal feed products. Protein ingredients derived from com are not widely used in human foods for a variety of reasons, one of which is the presence of sulphur dioxide at concentrations higher than commonly acceptable. Consequently, com-derived protein ingredients with low or lower sulphide dioxide concentrations might also be economically included for food applications such as breakfast cereals, nutrition bars, bakery products and processed meat formulations, among other things.

[0046] Although certain aspects of the invention have been described, the scope of the appended claims is not intended to be limited solely to these specific aspects. The claims are to be constmed literally, purposively, and / or to encompass equivalents. The scope of the present invention is defined by the appended claims. One or more of the objects of the invention are achieved by the appended claims.EXAMPLEMaterials

[0047] Three different products of untreated corn protein (com gluten slurry, cornPT-2118-WO-PCT gluten cake and corn protein isolate) have been provided from Cargill Orhangazi Plant. Among the distinguishing factors of the three corn protein products are their respective protein and water contents. The water content and protein content of the untreated com gluten slurry is 91.2 wt.% and 5.6 wt.%, respectively. The water content and protein content of the untreated corn gluten cake is 60.4 wt.% and 27.1 wt.%, respectively. The water content and protein content of the untreated com protein isolate is about 5 wt.% and 88.5 wt.%, respectively. Water content was measured according to TS EN ISO 6540. whereas protein content was measured according to the Kjeldahl method. A commercially available gas ozone device was used to generated gaseous ozone. The untreated corn protein (about 100 g) was placed in an ozone chamber and treated with gaseous ozone generated with the gas ozone device with exposure times between 30 and 60 minutes. The concentration of the ozone in the gaseous ozone was about 40 ppm. The amount of sulphur dioxide was measured again after treatment with ozone. Sulphur dioxide levels are measured according to method AO AC 962.16. Results are shown in Table 1.Table 1 : treatment of corn protein with gaseous ozonen.d. = not detectable (below limit of quantification)

Claims

PT-2118-WO-PCTCLAIMS1. A process for reducing sulphur dioxide in a protein-rich stream comprising(a) Providing a protein-rich stream, preferably derived from a wet com milling operation, wherein the protein-rich stream comprises more than 20% com protein on a dry weight basis; and(b) Treating the protein-rich stream with gaseous ozone, wherein the gaseous ozone comprises ozone in an amount between 1 and 200 ppm relative to the gaseous ozone to obtain a corn protein product.

2. Process according to claim 1, wherein the protein-rich stream has a sulphur dioxide content of at least 50 ppm or at least 100 ppm or at least 200 ppm, relative to the proteinrich stream.

3. Process according to claim 1 or 2, wherein the amount of ozone in the gaseous ozone is between 5 and 150 ppm, preferably between 8 and 100 ppm, more preferably between 10 and 50 ppm relative to the gaseous ozone.

4. Process according to any one of the previous claims, wherein treating the protein-rich stream with gaseous ozone is between 5 minutes and 2 hours, preferably between 15 minutes and 1.5 hour, more preferably between 25 minutes and 1.5 hour.

5. Process according to any one of the previous claims, wherein the com protein product has a sulphur dioxide content of less than 40 ppm, preferably less than 20 ppm, more preferably less than 10 ppm, relative to the corn protein product.

6. Process according to any one of the previous claims, wherein at least 75% of the amount of sulphur dioxide present in the protein-rich stream is removed after step b), preferably at least 85%, more preferably at least 95%, most preferably at least 99%.

7. Process according to any one of the previous claims, wherein the protein-rich stream is selected from the group consisting of com gluten meal, germ meal, com gluten cake, com protein concentrate, corn protein isolate and any combination thereof.PT-2118-WO-PCT8. Process according to any one of the previous claims, wherein the protein-rich stream comprises between 20 wt.% and 50 wt.% com protein on a dry weight basis, or between 50 wt.% and 98 wt.% corn protein on a dry weight basis.

9. Process according to any one of the previous claims, wherein the protein-rich stream comprises at least 80 wt.% corn protein on a dry weight basis.

10. Process according to any one of the previous claims, wherein the protein-rich stream comprises water in amount of less than 85 wt.% relative to the protein-rich stream, preferably less than 70 wt.%, more preferably less than 60 wt.%.

11. Process according to any one of claims 1-9, wherein the protein-rich stream comprises water between 1 and 10 wt.%, relative to the protein-rich stream, more preferably between 1 and 5 wt.%, most preferably between 2 and 4 wt.% relative to the proteinrich stream.

12. Process according to any one of the previous claims, wherein the ozone-treated proteinrich stream obtained during step (b) is subjected to washing the protein-rich stream with a solvent comprising water and a water-miscible solvent to obtain the corn protein product.

13. Process according to claim 12, wherein the washed ozone-treated protein-containing stream is dried before obtaining the com protein product.

14. Use of gaseous ozone to reduce the sulphur dioxide content in a protein-rich stream, preferably derived from a wet com milling operation, wherein the amount of ozone is between 1 and 200 ppm relative to the gaseous ozone.

15. The corn protein product obtainable by the process according to any one of claims 1-

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