METHOD FOR THE PREPARATION OF PROTEIN PREPARATIONS FROM SUNFLOWER SEEDS

Description

Application area

[0001] The invention relates to a method for obtaining functional protein preparations, in particular as protein ingredients for food, pet food, cosmetics and technical products, from sunflower seeds. State of the art

[0002] Against the backdrop of increasingly scarce agricultural land and resources, plant-based protein preparations for human nutrition and use in animal feed are gaining in importance. The growing demand for high-quality food and feed is leading to a rising need for nutritionally and technologically optimized protein preparations that can be provided easily and cost-effectively.

[0003] Pressing and extraction residues from sunflower oil production are a cost-effective source of food and feed proteins. Sunflower seeds are characterized by a hard shell with predominantly dark pigmentation and oil-rich pulp. While it is possible to remove the shells from these raw materials before oil extraction, complete or extensive removal of the shells reduces the yield and speed of the oil pressing process.

[0004] The pressing and extraction residues from sunflower oil production are primarily used as animal feed today. However, despite the high protein content, their use in feed is limited to just a few percent. This is due, firstly, to a very high hull content in the residue, which can exceed 25% by mass. Secondly, the proportion of interfering substances is very high, especially the content of secondary plant compounds such as polyphenols, tannins, and phytic acid. These components can collectively constitute several percent by mass in the residues and significantly impair the color, taste, and digestibility of the proteins. Therefore, press cakes and extraction residues from sunflower oil production are unsuitable for the production of high-quality protein ingredients for human food or pet food without further processing.

[0005] Sunflower seeds are typically processed with a focus on high oil yield. First, they are cleaned of impurities and conditioned with regard to temperature and humidity. Usually, some of the hulls are also removed. The prepared raw material is then mechanically pre-de-oiled by pressing to a residual oil content of between 8 and 20%. Subsequently, the remaining oil is extracted from the press cake using hexane or another solvent such as ethanol or supercritical CO₂. This leaves a residue with an oil content of less than 3% by mass and a protein content that ranges between 40 and 55% by mass, depending on the hull content.

[0006] According to current technology, sunflower seeds are predominantly pressed after partial dehulling. With partial dehulling, approximately 50% by mass of the seed coats remain in the raw material before oil extraction, which on average corresponds to a residual coat content of >15% by mass before pressing. For pressing in particular, current technology considers a coat content of at least 10% by mass necessary to facilitate oil drainage from the press, thereby increasing the pressing speed and reducing costs.

[0007] For several years, there have been approaches to obtaining protein preparations from the residues of sunflower oil production in the form of protein flours or concentrates, thus making them usable for food and high-quality feed applications. Several publications describe the production of protein preparations from sunflower seeds. These protein preparations are obtained through dry or wet processing (e.g., using solvents), with the protein remaining in the residue. However, the high proportion of undesirable components and the high crude fiber content limit the use of the residues for some food applications. Most protein flours and concentrates therefore have a limited range of applications and can only be used in low concentrations in animal feed.

[0008] EP 2 885 980 B1 describes, among other things, a process for obtaining sunflower protein as a protein-rich food or feed. Partially hulled sunflower seeds with a residual hull content of > 5% by mass are used to produce the feed. The seeds are pressed to achieve an oil content of ≥ 8% to ≤ 18% by mass and a protein content of ≥ 30% to ≤ 45%, based on dry matter. The influence of the residual hull content > 5% by mass on the digestibility of the proteins is not addressed. Furthermore, it must be assumed that the high crude fiber content and the high chlorogenic acid content of the product can severely limit its palatability and thus its usability as feed.

[0009] WO 2010097238 A2 describes a process for producing protein preparations from hulled sunflower seeds. In this process, the sunflower seeds are hulled to a residual hull content of ≤ 5% by mass, or hulled sunflower seeds with a residual hull content of ≤ 5% by mass are provided. The hulled sunflower seeds undergo partial mechanical de-oiling by pressing until the fat or oil content of the hulled sunflower seeds is between 10% and 35% by mass. After one or more extraction steps with at least one solvent, a defatted, protein-containing flour is obtained as the protein preparation. The protein preparation exhibits highly advantageous properties, both visually and functionally, which allow for direct use in the food or feed sector.The low temperatures achieved through pressing at under 80°C and desolvation at under 90°C ensure that good techno-functional properties are retained, a low degree of denaturation is maintained, and thus very good digestibility and bioavailability should be guaranteed. However, the low protein content of 55 to 65% by mass and the proportion of insoluble fiber significantly limit the applicability of these preparations, making it impossible, for example, to provide protein-rich sports nutrition or clear beverages.

[0010] For some time now, publications on preparations have been available, and protein preparations made from sunflower seeds with a higher protein content of over 70% by mass, and in some cases over 90% by mass, have been on the market. While their application potential is significantly greater than that of flours and concentrates due to the high protein content, their low brightness values ​​(determined according to the L*a*b* color space as L* below 60), discoloration (green, beige-brown hues), low protein solubility of <30%, and taste deficiencies prevent their widespread use in sensorially demanding applications. Furthermore, the processes are often very complex and consist of several solvent extractions (e.g.,Saeed and Cheryan, 1988, Sunflower Protein concentrates and isolates low in polyphenols and phytates, Journal of Food Science, 53 (4), 1127-1131) and / or aqueous extractions using different pH values ​​and various precipitation steps. Often, the sunflower seeds are indeed hulled, but then directly defatted with solvents without prior mechanical partial defatting, which further reduces the economic viability and industrial feasibility of the processes.

[0011] Furthermore, approaches are known in which the solubility of sunflower protein during extraction is improved by adding table salt or other salts (Pickardt et al. 2009, Optimisation of mild-acidic protein extraction from defatted sunflower (Helianthus annuus L.) meal, Food Hydrocolloids, 23 (7), 1966-1973; Pickardt et al. 2015, Pilot plant preparation of lightcoloured protein isolates from de-oiled sunflower (Helianthus annuus L.) press cake by mild-acidic protein extraction and polyphenol adsorption, Food Hydrocolloids, 44, 208-219). The publication by CLAUDIA PICKARDT et al.: "Isoelectric protein precipitation from mild-acidic extracts of de-oiled sunflower (L.) press cake", EUROPEAN FOOD RESEARCH AND TECHNOLOGY, Vol. 233, No. 1, 2011, pages 31-44, also describes a method for producing a protein preparation in which the protein extraction takes place at a pH of 6 in a concentrated saline solution (2.0 mol / l).However, such preparations have a very salty taste after extraction in aqueous solutions concentrated with salt, so that such methods do not lead to appealing preparations and also cause very high costs. Object of the present invention

[0012] The object of the present invention was to provide an economical process for the production of high-quality, sensorially appealing protein preparations with good techno-functional properties from sunflower seeds with a protein content greater than 75% by mass. The preparations should be very appealing in color and taste and exhibit good techno-functional properties. Furthermore, their high protein content should make them versatile for use in food and animal feed. Description of the invention

[0013] The problem is solved by the method according to claim 1. Advantageous embodiments of the method are the subject of the dependent patent claims.

[0014] The process described below surprisingly makes it possible to obtain at least two protein-rich fractions from sunflower seeds in a single processing step, one of which has a protein content greater than 75% by weight. These two or more fractions meet high sensory requirements and together contain more than 50% by weight, in advantageous embodiments more than 70% by weight, and particularly advantageously more than 90% by weight of the protein introduced into the process from sunflower flour, wherein the sunflower flour has a protein content > 35% by weight, preferably between 45% and 60% by weight, and particularly advantageously between 48% and 57% by weight.The use of a high proportion of the proteins added in the input of the process enables a high degree of economic efficiency compared to existing state-of-the-art processes, since, unlike other processes, several fractions can be used as protein-rich and sensorially appealing protein-rich food ingredients.

[0015] For the process according to the invention, protein-containing flour is first provided, which is obtained from hulled and defatted sunflower seeds, wherein the defatting comprises at least one mechanical step with a screw press or an extruder and optionally defatting with organic solvents such as ethanol or hexane, has an oil content of less than 8 wt%, advantageously less than 4 wt%, particularly advantageously less than 2 wt% (each determined by the Soxhlet method AOAC 963.15), and a hull content of less than 10 wt%, advantageously less than 5 wt%, particularly advantageously less than 1 wt% or less than 0.1 wt%. The flour used is characterized by a protein content of over 35 wt%, advantageously greater than 45 wt%, particularly advantageously greater than 48 wt% in dry matter (determined according to Dumas § 64 LFBG L 01.00-60 with a ratio factor of 6.25), and by good protein solubility.

[0016] Preferably, flour is used with a protein solubility in water at pH 6 greater than 15 wt%, advantageously greater than 20 wt%, and particularly advantageously greater than 25 wt%, and / or a protein solubility in water at pH 7 greater than 25 wt%, advantageously greater than 30 wt%, and particularly advantageously greater than 35 wt%, based on the protein content in the flour. The protein determination for determining the protein solubility is carried out in accordance with the protein solubility determination according to CV Morr and the determination of the NSI value according to the official AOCS method (Ba 11-65; 1993) or AACC (46-23; 1990).

[0017] To produce flour with such high protein solubility, particularly gentle conditions must be ensured during oil removal using screw presses or extruders and solvents, along with a significant reduction of interfering foreign substances that could affect solubility. Surprisingly, however, it turns out that a certain residual solvent content in the flour used does not, as expected, negatively affect protein solubility. On the contrary, certain amounts of solvent in the flour have a positive effect on subsequent processing. Solubility is particularly good with a residual content of at least one organic solvent (ethanol, propanol, methanol, or hexane) greater than 0.001% by mass, advantageously greater than 0.01% by mass, and particularly advantageous greater than 0.05% or 0.1% by mass.It is shown that within this concentration range, with an upper limit of approximately 1 mass %, the solubility of the protein increases with increasing solvent content in the flour.

[0018] The flour particles are advantageously finely ground before extraction. The D90 (90% of the mass of particles smaller than the specified particle size (determined by laser diffraction in n-butanol)) is in the range of 100 µm to 2500 µm; a D90 smaller than 500 µm or smaller than 250 µm is advantageous. Protein dissolution from the flour can be further accelerated if the D90 is reduced to below 100 µm, for example, by further fine grinding, and particularly advantageously to below 50 µm.

[0019] The high protein concentration in the flour and, preferably, the good solubility of the protein it contains are advantageous because an aqueous extraction step is carried out later in the process according to the invention. The high protein solubility is achieved by using flour in which the temperatures during pressing, oil removal with organic solvents, and desolvation are not set too high, so that the solubility of the proteins in the residue remains at a high level. If all these steps are carried out at temperatures below 120 °C, preferably below 100 °C, and particularly advantageously below 80 °C, thermal damage can be largely avoided and the protein solubility preserved. Therefore, flours that have been pressed, oil-removed, and desolvated below the aforementioned temperatures should be used advantageously.

[0020] As mentioned above, the protein-containing flour made from defatted sunflower seeds has a hull content of less than 10% by mass, advantageously less than 5% by mass, or less than 1% by mass, and particularly advantageously less than 0.5% or even 0.1% by mass. Particularly hull-free or nearly hull-free flours make it possible, after the single or multiple extraction according to the invention, to utilize both the protein from the extract(s) or at least one of the extracts and the protein from the remaining refined product for food applications.

[0021] In the process according to the invention, at least one aqueous extraction is carried out with the provided sunflower flour. For this purpose, the flour and a defined excess of water (e.g., a water-to-flour ratio greater than 3:1, preferably greater than 5:1, particularly advantageous equal to or greater than 10:1) are mixed in a stirring vessel, kept in suspension for a period of time (advantageously between 10 and 60 minutes), and the suspension is subsequently separated into a liquid phase (extract) and a solids-rich phase (raffinate) using a continuous centrifuge, preferably a decanter. The extraction, the separation of both phases, and the further treatment and, if necessary, drying of both fractions are carried out largely in the absence of oxygen and / or with the addition of antioxidants and / or reducing agents, so that it is possible to obtain, after extraction and, if necessary,Drying yields a high-quality, light-colored protein preparation with good technofunctional properties from both the extract (or one of the extracts) and, with a sufficiently low shell content, from the raffinate. After analytically fine milling, both fractions exhibit an L* value greater than 70, in advantageous formulations greater than 80, and particularly advantageously greater than 90, based on the L*a*b* color space.

[0022] To achieve the simultaneous extraction of two high-quality, light-colored protein preparations from the flour, a low hull content and a high protein content in the flour are required, as already mentioned. Good protein solubility (solubility parameters as described above) can further improve the results. Furthermore, the extraction process according to the invention must be carried out in such a way that oxidation of the sunflower seed components is largely avoided, or the components prone to oxidation are largely separated from the two fractions, e.g., in an aqueous pre-extraction of the flour.

[0023] This can be achieved particularly advantageously by carrying out at least one aqueous extraction – preferably at pH values ​​below 6 – under exclusion of air, i.e., after applying a vacuum or adding nitrogen, argon, CO₂, or other inert gases, and / or by using food-grade antioxidants and / or reducing agents such as sodium bisulfite, sodium sulfite, or cysteine. If oxidation is largely reduced or completely avoided, it is found that both the protein fraction obtained from the extract and the raffinate exhibit an L* value of over 70 after drying and analytical-fine milling. With complete exclusion of oxygen and the use of antioxidants and / or reducing agents, it is also possible to achieve L* values ​​above 80 in both fractions. This has not yet been achieved according to the current state of the art.

[0024] Extraction at reduced atmospheric pressure (vacuum) is advantageously carried out by adjusting the pressure in the gas phase of the closed extraction vessels to less than 200 mbar, preferably less than 100 mbar. The oxygen concentration in the water or extract should be considered the target parameter. It is advantageous to aim to reduce the O₂ concentration in the water used for extraction or directly in the extract to values ​​below 7 mg / l, preferably below 3 mg / l, particularly advantageous below 0.5 mg / l, or better still below 0.1 mg / l.

[0025] Should it not be possible to reduce the concentration below these values ​​under vacuum, particular advantages regarding the color and brightness of the protein preparations become apparent if the dissolved oxygen is largely removed from the water used for extraction by blowing in highly concentrated (> 90 vol.%) nitrogen or argon and / or treating it with ultrasound, thus reducing the oxygen concentration below the values ​​mentioned above. In this way, values ​​for dissolved oxygen below 0.1 mg / l can be advantageously achieved, in some cases even below 0.05 mg / l, which significantly limits the extent of discoloration.

[0026] As an alternative or additional step, it is advantageous to add ascorbic acid, citric acid, or another colorless, water-soluble antioxidant and / or reducing agent such as sodium bisulfite, cysteine, etc., to the water used for extraction. This also suppresses darkening and results in lighter preparations. Whether the addition of antioxidants and / or reducing agents is sufficient to suppress oxidation, or whether the additional measures described above are necessary to further reduce the oxygen concentration, can be varied depending on the desired result. Furthermore, it was surprisingly found that the addition of reducing agents improved some functionalities, such as the solubility and emulsifying properties of the preparations.

[0027] Ideally, the methods mentioned for avoiding oxidation are combined to carry out the procedure.

[0028] In comparison, it is evident that the color of the preparations darkens considerably when a pH of 7.5 or higher is selected during extraction without the described measures. In an embodiment of the inventive process, in which the above measures are combined—i.e., after purging the oxygen, for example, with nitrogen (nitrogen content greater than 90 vol%) or argon, and adding, for example, 0.01 to 1 g of ascorbic acid and / or 0.01 to 1 g of cysteine ​​or cystine per liter of water for extraction—it is shown that even when adjusting the pH of the extract to values ​​above 8.5, light-colored protein preparations can still be obtained if the extract is subjected to ultrafiltration and / or diafiltration. A particularly light color can also be observed after reducing the pressure during extraction to values ​​below 50 mbar.The combination of low-oxygen or oxygen-free extract, the addition of antioxidants and / or reducing agents, and the use of ultrafiltration and, advantageously, also diafiltration of the extract proves to be a particularly efficient process combination to ensure that the protein fraction obtained from the extract is color-stable after drying, i.e., does not undergo any greying or other type of dark discoloration during storage.

[0029] It has been found that prior treatment of the flour to reduce its air or oxygen content offers further advantages, especially if the water used for extraction is already largely free of dissolved oxygen. For example, it has been shown that lighter protein preparations can be obtained from sunflower flour treated by vacuum below 200 mbar, advantageously below 50 mbar, or by blowing in nitrogen (or another suitable gas) before extraction, compared to flour that has not been pre-treated to remove air contained in the bulk material. Preferably, the partial pressure of oxygen in the flour should be reduced to below 50 mbar, better below 20 mbar, and particularly advantageously below 10 mbar.

[0030] After the complete or partial removal of oxygen from the water, a process which can be further supported by heating the oxygenated water to temperatures above 20°C, advantageously above 40°C, and particularly advantageously above 50°C, the pH value can be adjusted between 4 and 7 during the extraction process, according to the invention. This can be determined by the oxygen content in the water or optimized with regard to the desired separation result. For oxygen contents above 5 mg / l, the pH value according to the invention is below 6.5, advantageously below 6.

[0031] However, this does not mean that the highest possible pH values ​​should always be chosen if the aforementioned oxygen levels are not met. Rather, a low O₂ value can be set below 0.1 mg / l, and antioxidants and / or reducing agents can be added, while still selecting a pH of 6 to achieve specific properties, a defined protein composition, or a particularly light color. Since only the albumins from sunflower seeds dissolve at pH 6, it can therefore be advantageous to set the pH to 6 and extract only the albumins.

[0032] In a particularly advantageous embodiment of the process, the pH value is adjusted by the added antioxidants such as ascorbic acid.

[0033] In the process according to the invention, extraction is preferably carried out with a flour that is ground to a defined particle size distribution prior to extraction and to which a certain amount of water is added for extraction. After extraction, a separation between the raffinate and the extract takes place. For further protein extraction, a further aqueous extraction with the raffinate is advantageously carried out. After at least one separation of extract and raffinate, the raffinate is subjected to drying and, if necessary, milling to achieve a preferred particle size distribution, as already described above in the section on the preferred milling of the flour.The extract is preferably freed from sugars and other compounds with correspondingly small molecular sizes either by ultrafiltration or diafiltration (or both), or the proteins are concentrated by precipitation, preferably at the isoelectric point of the proteins, and / or ultrafiltration. The concentrated protein is then stabilized, for example by drying or freezing, and optionally subsequently adjusted to the particle size distribution mentioned above by milling.

[0034] The protein preparation from the raffinate has a protein content greater than 25% by mass, advantageously greater than 40% by mass, and particularly advantageously greater than 50% by mass, and a sugar content (total of mono- and disaccharides) of less than 6% by mass, advantageously less than 1% by mass, and particularly advantageously less than 0.5% by mass. The protein fraction obtained from the raffinate also has a chlorogenic acid content of less than 1% by mass, advantageously less than 0.5% by mass, and particularly advantageously less than 0.1% by mass.

[0035] Such a low concentration of chlorogenic acid, below 0.1 wt%, combined with a relatively high protein content, preferably above 50 wt%, in the protein preparation obtained from the raffinate, has the advantage over previously known bran-free flours with similar protein contents that no discoloration occurs when a neutral or alkaline pH is adjusted in a food application, a cosmetic application, or in pet food, or when the product is stored for an extended period. Such pH values ​​or long storage times cannot be achieved with conventional flours according to the prior art without discoloration.

[0036] By using oxygen-reduced and oxidation-minimized extraction conditions, it is surprisingly possible to produce a high-quality, light-colored preparation from the raffinate and at the same time to obtain an extract from which, in particular by means of ultrafiltration and / or diafiltration and / or precipitation, a neutral and light-colored protein concentrate with over 75% protein by mass or even a protein isolate with a protein content of over 90% by mass can be obtained.

[0037] Here, too, the advantage of the reduction of the oxygen content or the reduction of oxidation according to the invention becomes apparent. When these measures are implemented, ultrafiltration of sugars and other compounds with low molecular weight on the one hand, and of proteins with a molecular weight above 1000 Da on the other, is much more effective than if this is not the case. This is not possible with membrane separation if the oxidation-limiting measures according to the invention are not selected. With the process according to the invention, it is also easier to use adsorbents for separating interfering components from the extract. Due to the largely oxidation-free environment, fewer proteins are deposited on the surfaces of the adsorbents.

[0038] It turns out that even from defatted flours of dark color, which can have a bran content of up to almost 10%, very light protein preparations with L* values ​​above 70, advantageously above 80, can be obtained.

[0039] The proposed method yields a preparation with the following properties from the extract or at least one of the extracts: Protein content greater than 75 wt%, preferably greater than 80 wt%, particularly preferably greater than 90 wt%; bright optical appearance with L* values ​​from the L*a*b* color space greater than 70, advantageously greater than 80, particularly advantageously greater than 90; emulsifying capacity greater than 200, advantageously greater than 400, particularly advantageously greater than 500 ml oil / g protein; protein solubility at pH 7 greater than 10 wt%, preferably greater than 30 wt%, particularly advantageously greater than 40 wt% or 50 wt%, based on the protein content in the preparation; preferably a particle size distribution with a D90 value (quantity of particles below the size corresponds to 90%): less than 500 µm, advantageously less than 250 µm, particularly advantageously less than 100 µm

[0040] The refined product is used to obtain a preparation with the following properties: Protein content greater than 25 wt%, advantageously greater than 40 wt%, particularly advantageous greater than 50 wt%; bright optical appearance with L* values ​​from the L*a*b* color space greater than 70, advantageously greater than 80, particularly advantageous greater than 90; emulsifying capacity greater than 250, advantageously greater than 400, particularly advantageous greater than 500 ml oil / g protein; protein solubility at pH 7 greater than 5 wt%, preferably greater than 20 wt%, particularly advantageous greater than 30 wt%, based on the protein content in the preparation; water binding > 1 g per g dried raffinate; preferably a particle size distribution with a D90 value: less than 1000 µm, advantageously less than 500 µm, particularly advantageous less than 250 µm; preferably a polyphenol content in the raffinate < 1 wt%, advantageously < 0.5 wt% and particularly advantageously < 0.1 wt% (determination method: Weisz et al. 2009). Identification and quantification of phenolic compounds from sunflower (Helianthus annuus L.) kernels and shells by HPLC-DAD / ESI-MS, Food Chemistry, 115 (2), 758 - 765) Preferably a residual organic solvent content of < 50 mg / kg, particularly advantageous of < 10 mg / kg .

[0041] In summary, the proposed procedure involves the following procedural steps: 1) Providing protein-containing flour from defatted sunflower seeds with a protein content > 35 wt%, oil contents less than 8 wt%, advantageously less than 4 wt%, particularly advantageously less than 2 wt% (Soxhlet method AOAC 963.15) and shell contents less than 10 wt%, advantageously less than 5 wt%, particularly advantageously less than 1 wt% or less than 0.1 wt%, preferably with a protein solubility at pH 6 of greater than 15 wt%, advantageously greater than 20 wt% based on protein in the flour and / or a protein solubility in water at pH 7 of greater than 25 wt%, advantageously greater than 30 wt%, particularly advantageously greater than 35 wt%.-% based on the protein content in the flour 2) Extraction of the flour with water in the pH range greater than 4, advantageously greater than 5, particularly advantageously greater than 6 but less than 7 3) Before or during this process, reduction of the oxygen concentration in the water to values ​​less than 7 mg / l, advantageously less than 2 mg / l, particularly advantageously less than 0.5 mg / l or less than 0.1 mg / l and / or reduction of the oxidation activity by one or more of the following steps: a. Reduction of the air pressure in the extraction vessels to less than 200 mbar, preferably less than 100 mbar and / or b. Adjustment of the temperature of the water to be used for extraction to values ​​above 20°C, advantageously above 40°C, particularly advantageously above 50°C, whereby dissolved oxygen escapes, and / or c. Infusion of nitrogen, CO₂, argon or another inert gas with a concentration above 90 vol.%, advantageously greater than 99 vol.%-%, by introducing into the water used for extraction, which is advantageously heated to over 20°C, or into the extract, or by bringing it into contact with the water or the extract by providing nitrogen, CO₂, argon, or another inert gas above the water / extract surface, so that the nitrogen, CO₂, argon, or the inert gas displaces the oxygen dissolved in the water / extract, and in the case of nitrogen, an N₂ concentration greater than 10 mg / l, advantageously greater than 15 mg / l, and particularly advantageously greater than 20 mg / l, is achieved, and / or by adding antioxidant and / or reductively active components (e.g.,4) Citric acid, ascorbic acid, sulfites, cysteine, or others) before or during extraction. 5) Preferably: Adjusting the pH of the water to values ​​between 5.5 and 6.5. 6) Separating the solid and the extract. 7) Preferably: Repeating the extraction process at a higher pH, particularly advantageous being a first extraction at pH values ​​between 5.5 and 7 and a second extraction at pH values ​​between 7.5 and 9. 8) Preferably: Concentrating the proteins in the extract by precipitation or ultrafiltration and / or diafiltration. 9) Optionally, drying the extract and (optionally) the raffinate or the concentrated protein fractions, and optionally milling to achieve a desired particle size distribution. Example implementation: Implementation:

[0042] Sunflower flour made from dehulled seeds with a hull content of less than 1% by mass (protein content 55%; protein solubility 40%; oil content 2.5% by mass) is suspended in distilled water at a ratio of 1:10 (based on the dry matter of the flour). The water used for this purpose was purged with nitrogen for one hour prior to use to remove dissolved oxygen. Additionally, the pH of the water was adjusted to 6 with ascorbic acid before the flour was added. After adding the flour to the water, the pH was readjusted to 6, and the mixture was then stirred for 30 minutes at room temperature.

[0043] After this pre-extraction, the suspension was centrifuged for 10 minutes at 8570 g and 20°C. The residue from the centrifugation was extracted again at pH 6 (second pre-extraction) and centrifuged as described above. These pre-extractions remove, among other things, undesirable phenolic components from the flour. The residue from the centrifugation was then resuspended in water at a ratio of 1:10 (based on the dry mass) and adjusted to a pH of 8.5 with sodium hydroxide solution. The suspension was then stirred for 30 minutes at room temperature to extract the proteins. The water used for this purpose was purged with nitrogen for 1 hour before use.

[0044] After protein extraction, the residue (raffinate) and supernatant (extract) were separated by centrifugation (10 min, 20°C, 8570 g). The raffinate was stabilized by freeze-drying, while the resulting extract was subjected to protein precipitation.

[0045] For protein precipitation, the pH of the extract was adjusted to 6 with ascorbic acid and stirred for 30 minutes at room temperature. The precipitated proteins were then obtained by centrifugation (10 minutes, 20°C, 8570 g). The resulting protein curd was freeze-dried for stabilization. Products:

[0046] a) Protein product from extract phase: Protein content: 85% Protein solubility (pH 7): 12% Emulsifying capacity: 230 mL oil / g L* value (L*a*b color space): 80 b) Refined: Protein content: 40% Protein solubility (pH 7): 25% Water binding: 1.2 g / g Emulsifying capacity: 485 mL oil / g L* value (L*a*b color space): 80 Polyphenol content: 0.2 wt%

Claims

1. A process for producing protein preparations from sunflower seeds with at least the following steps: - providing a protein-containing flour from dehulled and deoiled sunflower seeds with -- a hull content <10% by mass, -- an oil content <8% by mass, -- a protein content >35% by mass and - performing at least one or more extraction steps with water at a pH of more than 4 and less than 7 with the protein-containing flour, after which one or more extraction step(s) a liquid phase is obtained as an extract and a solid-rich phase is obtained as a raffinate, - separating the extract and the raffinate, and - concentrating and / or drying the extract and drying the raffinate, - wherein before and / or during the one or more extraction step(s) an oxygen concentration in the water is reduced to a value <7 mg / l and / or an oxidation activity is reduced by the addition of antioxidant components to the water and / or components with reductive effect are added.

2. The process according to Claim 1, characterized in that the protein-containing flour has a protein solubility in water at pH 6 of >15% by mass and / or at pH 7 of >25% by mass relative to the protein content in the flour.

3. The process according to Claim 1 or 2, characterized in that in order to reduce the oxygen concentration in the water, the one or several extraction steps are carried out under air pressure that has been reduced to <200 hPa.

4. The process according to any one of Claims 1 to 3, characterized in that in order to reduce the oxygen concentration in the water, nitrogen, carbon dioxide, argon or another inert gas with a concentration of more than 90% by volume is blown into the water or brought into contact with the water surface before and / or during the one or more extraction step(s).

5. The process according to any one of Claims 1 to 4, characterized in that the oxygen concentration in the water is reduced by a treatment with ultrasound.

6. The process according to any one of Claims 1 to 5, characterized in that in order to reduce the oxygen concentration in the water a temperature of the water is adjusted to a value above 20 °C.

7. The process according to any one of Claims 1 to 6, characterized in that an oxygen content of the protein-rich flour is reduced before the one or more extraction step(s) by means of a vacuum or by blowing in carbon dioxide or an inert gas.

8. The process according to Claim 7, characterized in that the oxygen content in the protein-rich flour is reduced to an oxygen partial pressure below 50 hPa in the protein-rich flour.

9. The process according to any one of Claims 1 to 8, characterized in that the one, or at least one of the one or more extraction steps is performed at pH values <8.

10. The process according to any one of Claims 1 to 9, characterized in that the separated extract is concentrated by ultrafiltration and / or diafiltration and / or precipitation.

11. The process according to any one of Claims 1 to 10, characterized in that the flour is subjected to several extraction steps with water, wherein at least one of the extraction steps is performed at pH values between 5.5 and 7 and subsequently another of the extraction steps is performed at pH values between 7.5 and 9.

12. The process according to any one of Claims 1 to 11, characterized in that the protein-containing flour is ground before the extraction to obtain a particle size distribution at which a percentage by mass of 90% of the particles has a particle size <100 µm, as determined by laser diffraction in n-butanol.

13. The process according to any one of Claims 1 to 11, characterized in that the protein-containing flour is ground before the extraction to obtain a particle size distribution at which a percentage by mass of 90% of the particles has a particle size between 100 µm and 2500 µm, as determined by laser diffraction in n-butanol.

14. The process according to any one of Claims 1 to 13, characterized in that the protein-containing flour provided has a residual content of a solvent used for the deoiling which is in the range between 0.001 and 0.4% by mass.