Brightened functional vegetable fiber

Abstract

The invention relates to a method for producing a brightened functional plant fiber and to a brightened functional plant fiber which can be obtained using this method. The invention additionally relates to a brightened functional plant fiber having a brightness value of L* > 68, to the use of the brightened functional plant fiber as a thickening or structuring agent in various industrial products, to a mixture of the brightened functional plant fiber and a soluble pectin, and to a food product, a food supplement, a feed product, a beverage, a cosmetic product, a pharmaceutical product or a medical product which has been produced using the brightened functional plant fiber according to the invention.

Description

Lightened functional plant fiber The present invention relates to a process for producing a brightened functional plant fiber and to a brightened functional plant fiber obtainable from this process. The invention also relates to a brightened functional plant fiber with a brightness value of L* > 68. Furthermore, the invention relates to the use of the brightened functional plant fiber as a thickening or structuring agent in various industrial products. Furthermore, the invention relates to a mixture of the brightened functional plant fiber with a soluble pectin. Furthermore, the invention relates to a food, dietary supplement, feed product, beverage, cosmetic product, pharmaceutical product, or medical device produced using the brightened functional plant fiber according to the invention. Background of the invention Dietary fiber is a largely indigestible food component, usually carbohydrates, found primarily in plant-based foods. For simplicity, dietary fiber is divided into water-soluble fiber, such as pectin, and water-insoluble fiber, such as cellulose. Dietary fiber is considered an important component of the human diet. The consumption of fiber is considered beneficial to health. The water-soluble fiber in food increases the volume of food without significantly increasing its energy content. If it is not sufficiently swollen before ingestion, it absorbs additional water in the stomach. The resulting increase in volume leads to an increased feeling of satiety. Furthermore, fiber prolongs the time the food stays in the stomach and intestines. Water-soluble fiber such as pectin binds bile acids from cholesterol metabolism in the intestines, thus leading to a lowering of cholesterol levels. Soluble fiber, in particular, is thought to reduce glucose absorption, slow glucose adsorption and starch processing, and control postprandial glucose levels in serum. Those who consume a lot of fiber have a reduced risk of numerous lifestyle diseases, especially obesity, hypertension, coronary heart disease (CHD), stroke, diabetes, and various gastrointestinal diseases. Diseases. Accordingly, the German Nutrition Society (DGE) recommends a minimum of 30 g of fiber as a guideline for daily intake. The use of plant fibers as dietary fiber in food production is becoming increasingly important. One reason for this is the fact that plant fibers represent a mixture of insoluble fibers such as cellulose and soluble fibers such as pectin, thus ideally providing the health-promoting spectrum of effects listed above. Through the use of plant fibers, the functional properties of food products can be specifically optimized and adjusted, for example, with regard to viscosity, emulsion formation, gel formation, dimensional stability, or texture. Plant fibers can thus replace other less accepted or even harmful additives in food. As non-E-classified substances, they lead to simpler product labeling and thus increased product acceptance. Plant fibers can be obtained from various raw materials, which often arise as processing residues during juice production. Depending on the starting material, however, plant fibers can be produced that exhibit a distinct coloration. For example, apple fibers exhibit a distinct brownish coloration compared to the almost colorless citrus fibers and thus appear darker overall. The use of these colored plant fibers in food production can lead to unwanted coloring of the resulting food, which reduces consumer acceptance. Therefore, bleaching agents and / or oxidizing agents are used in the prior art to decolorize or brighten such colored fibers. However, the production of plant fibers using bleaching agents and / or oxidizing agents must be viewed critically, not least from the perspective of consumer acceptance. US 2008 / 233238 A1 relates to a process for producing colorless fibers by contacting carrot raw materials with supercritical carbon dioxide. It teaches contacting under conditions of 70-120 °C and a pressure of more than 7000 psi (483 bar), whereby color-providing carotenes are extracted from the carrot raw material (see claim 1,

[0007] -

[0011] ). The process is limited to carrot raw material as the starting material. There is therefore a need for new processes for the production of bleached and / or decolorized plant fibers and the bleached and / or decolorized plant fibers produced thereby. The present invention is based on the object of improving the state of the art or offering an alternative to it. Summary of the invention According to a first aspect of the present invention, the stated object is achieved by a process for producing a brightened functional plant fiber, the process comprising: (a) providing a depectinized raw material containing cell wall material of a plant; (b) optionally washing the depectinized raw material provided in step (a) with an aqueous solution; (c) optionally separating the washed material from step (b) from the aqueous solution; (d) degrading lignin by incubating an aqueous suspension of the depectinized raw material from step (a), the washed material from step (b) or the material separated from the aqueous solution from step (c) with a lignin-degrading incubation solution, wherein the lignin-degrading incubation solution is preferably an alkaline incubation solution and / or an enzymatic incubation solution; (e) separating the incubated material from step (d) from the lignin-degrading incubation solution; (f) washing the material separated in step (e) with an aqueous solution; (g) separating the washed material from step (f) from the aqueous solution; (h) washing the separated material from step (g) at least twice with an organic solvent and subsequently separating the washed material from the organic solvent in each case; (i) optional additional removal of the organic solvent by contacting the washed material from step (h) with steam; (j) drying the material from step (h) or (i) comprising drying at normal pressure or vacuum drying to obtain the brightened functional plant fiber. The production process according to the invention leads to brightened functional plant fibers with a large internal surface, which also increases the water binding capacity and is accompanied by good viscosity formation. These fibers have sufficient strength in aqueous suspension so that no additional shear forces are required in order to achieve optimal rheological properties such as viscosity or texturing. As the inventors have found, the bleached functional plant fibers produced by the process according to the invention exhibit good rheological properties. The fibers according to the invention can be easily rehydrated, and the advantageous rheological properties are retained even after rehydration. The inventors have surprisingly found that the advantageous rheological properties of the functional fibers are retained when bleached by enzymatic treatment and especially by alkaline treatment. The inventive manufacturing process results in bleached, functional plant fibers that are highly tasteless and odorless, making them ideal for use in the food industry. The inherent flavor of the other ingredients is not masked, allowing them to develop optimally. Furthermore, the process according to the invention results in plant fibers with high brightness. In other words, the fibers produced according to the invention exhibit virtually no browning. This enables their versatile use, even where browned and / or colored fibers lead to undesirable coloring of the product. For example, the fibers produced according to the invention can be used to thicken a cream sauce. The use of dark or colored fibers for such a cream sauce would result in an atypical color and brightness of the sauce and consequently impair consumer acceptance of such a sauce. The brightened functional plant fiber obtained from the process according to the invention exhibits a higher brightness than a comparably produced fiber that has not undergone the lignin-degrading step (d). The brightness can be quantified, for example, using the L* value from the L*a*b* color space (also known as the CIElab color space). In addition to the CIElab color space, the CIELIIV color space and CIELCH color space are also used to determine a color, both of which also have a brightness component L*. Another color system is the Munsell color system, in which brightness is described by the Munsell value. The fiber produced according to the invention has a brightness that is at least 5%, preferably at least 10%, and particularly preferably at least 25% higher than that of a comparably produced plant fiber which, however, has not undergone the lignin-degrading step (d). The brightness can be increased, for example, by 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, or 50%. The brightness of the plant fiber can be described using any color space, with the brightness preferably being described as an L* value according to the L*a*b* color space. The inventors have surprisingly found that in the process according to the invention, no addition of further bleaching agents and / or oxidizing agents is necessary to obtain a brightened functional plant fiber. The brightening thus occurs solely through the lignin-degrading step in (d). It is obvious to the person skilled in the art that other process steps can also lead to a slight change in brightness, with the substantial brightening occurring through the lignin-degrading step (d). Preferably, none of the other process steps results in a brightening of more than 5%, further preferably of more than 1%, particularly preferably of more than 0.5%, and furthermore preferably of more than 0.1%. With particular preference, none of the other process steps results in a brightening. Without wishing to be bound by theory, the inventors assume that the lignin present in the depectinized raw material reacts, among other things, via oxidative processes to form melanin and thereby colors the resulting fiber or leads to browning. Lignin is the most abundant aromatic biopolymer, accounting for approximately 30% of the Earth's organic carbon. Lignin is an important component of plant cell walls, where it supports structure, aids water and nutrient transport, and protects against chemical and biological attack. However, lignin is not a single substance, but rather a group of phenolic macromolecules composed of various monomer building blocks. Accordingly, lignin, with its complex molecular structure, cannot be described by a single structural formula. The combination of similar basic molecules creates a densely cross-linked, amorphous mass. Compared to polysaccharides, this structure has significantly fewer polar groups, making lignins hydrophobic and thus insoluble in water and many other solvents. Due to their high heterogeneity, lignins are more difficult to degrade biologically and chemically than other natural substances. Various methods of lignin degradation (ligninolysis) are known, including microbial degradation, chemical degradation (including through metal-catalytic processes or lowering the pH value), and physical degradation, for example, through steam explosion. Microbial and / or chemical degradation, as described above, can be achieved through the incubation in step (d). Preferably, however, the degradation of the lignin is carried out by incubating an aqueous suspension of the depectinized raw material from step (a), the washed material from step (b) or the material separated from the aqueous solution from step (c) with a lignin-degrading incubation solution, wherein the lignin-degrading incubation solution is an alkaline incubation solution or an enzymatic incubation solution. The alkaline incubation solution is characterized by the fact that it is not only alkaline in itself, i.e., has a pH greater than 7, but also continues to have an alkaline pH even after contact with the material from steps (a), (b), or (c). In other words, the alkaline incubation solution serves not only to increase the pH of the starting material, but also to achieve an alkaline pH during step (d). The enzymatic incubation solution comprises at least one lignin-degrading enzyme. In general, a combination of the two solutions is also conceivable, so that the lignin degradation in step (d) can take place at an alkaline pH in the presence of lignin-degrading enzymes. The starting material is a depectinized raw material. This refers to a plant-based raw material that has a low pectin content. The pectin content, based on the dry mass of the starting material, is preferably less than 25 wt.%, more preferably less than 15 wt.%, and especially preferably less than 10 wt.%. Depectinized raw materials regularly arise during pectin extraction. The raw material is therefore expediently a depectinized raw material arising during pectin extraction. Thus, the raw material is not an untreated plant-based raw material, but rather an end product of pectin extraction. Such a raw material Represents the solid residue of a pectin extraction after separation of the pectin extract as a liquid pectin-containing phase. Processing residues from juice production are often used for pectin extraction. The pectin content can be, for example, less than 25 wt.%, less than 20 wt.%, less than 15 wt.%, less than 10 wt.%, or less than 5 wt.%. According to optional step (i), the solvent content can be further reduced by contacting the material with steam. This is preferably carried out using a stripper in which the material is contacted countercurrently with steam as the stripping gas. It may further be provided to moisten the material with water after step (h) or (i) before drying. This is preferably done by introducing the material into a moistening screw and spraying it with water. In step (j), the washed material from step (h) or the stripped material from step (i) is dried, wherein the drying comprises drying under normal pressure or by means of vacuum drying. Examples of suitable drying processes using atmospheric pressure include fluidized bed drying, moving bed drying, belt dryers, drum dryers, or paddle dryers. Fluidized bed drying is particularly preferred. This has the advantage of drying the product in a loosened state, which simplifies a subsequent optional grinding step. Furthermore, this drying method prevents damage to the product due to local overheating due to the easily controllable heat input. Drying under atmospheric pressure in step (j) is advantageously carried out at a temperature of between 50°C and 130°C, preferably between 50°C and 100°C, and particularly preferably between 50°C and 60°C. Following drying, the product is advantageously cooled to room temperature. In an alternative embodiment, the drying according to step (j) comprises vacuum drying and preferably consists of vacuum drying. During vacuum drying, the washed material is exposed to a negative pressure as a dry product, which reduces the boiling point and thus leads to evaporation of the water even at low temperatures. The heat of vaporization continuously extracted from the dry product is suitably supplemented from the outside until the temperature is constant. Vacuum drying has the effect of reducing the equilibrium vapor pressure. reduced, which promotes capillary transport. Vacuum drying preferably takes place at an absolute vacuum of less than 400 mbar, preferably less than 300 mbar, more preferably less than 250 mbar, and particularly preferably less than 200 mbar. The drying under vacuum in step (j) is advantageously carried out at a jacket temperature of between 40 °C and 100 °C, preferably between 50 °C and 90 °C, and particularly preferably between 60 °C and 80 °C. Following drying, the product is advantageously cooled to room temperature. The bleached functional plant fibers according to the invention are obtained from natural raw materials and thus represent natural ingredients with known positive properties. Plant fibers are established and accepted in the food industry, so that corresponding compositions can be used immediately and internationally without lengthy approval procedures. The invention in detail According to a first embodiment, the depectinized raw material from step (a) is a residue from the processing of apples, beetroot, peas, sugar beet, or carrots. These processing residues are inexpensive, available in sufficient quantities, and offer a sustainable and ecologically sound source for the plant fibers according to the invention. The depectinized raw material is preferably a residue from the pectin extraction of apples, and particularly preferably a depectinized apple pomace. The residue and the pomace may contain apple cell wall material, with the residue preferably being selected from the group consisting of apple peel, core, seeds, and pulp. All cultivated apples known to the expert can be used as apples. Pectin extraction breaks down the pectin-containing starting material so that the depectinized raw material contains broken down fibers and can therefore be considered a functional plant fiber. According to the invention, the depectinized raw material can be incubated directly with the lignin-degrading incubation solution according to step (d). However, according to the optional step (b), the depectinized raw material can first undergo an aqueous washing step. This step allows water-soluble substances, such as fruit sugars or substances remaining from the pectin extraction, to be removed. At the same time, the pH of the depectinized raw material can be partially neutralized. Particularly in the case of a prior acidic pectin extraction, it can be advantageous to significantly reduce the acid content in the depectinized raw material. For the purposes of the invention, the "aqueous solution" refers to the aqueous liquid used for washing. The mixture of this aqueous solution and the digested material is referred to as the "washing mixture." Advantageously, the washing in step (b) is carried out with water as an aqueous solution. The use of deionized water or drinking water is particularly advantageous here. In one embodiment, the aqueous solution consists of more than 50 vol% water, preferably more than 60, 70, 80, or even 90 vol%. In a preferred embodiment, the aqueous solution contains no organic solvent and, in particular, no alcohol. This results in a water-based wash and not a water-alcohol exchange as occurs in fiber washing with a mixture of alcohol and water, where this mixture contains more than 50 vol% alcohol and typically has an alcohol content of more than 70 vol%. Alternatively, a salt solution with an ionic strength of I < 0.2 mol / 1 can be used as the aqueous solution. The washing according to step (b) is advantageously carried out at a temperature of 30°C to 90°C, preferably from 40°C to 80°C, and particularly preferably from 50°C to 70°C. The washing can be carried out, for example, at a temperature of 30°C, 35°C, 40°C, 45°C, 50°C, 55°C, 60°C, 65°C, 70°C, 75°C, 80°C, 85°C, or 90°C. The contacting time in step (b) with the aqueous solution is from 10 minutes to 2 hours, preferably from 30 minutes to one hour. Washing can be carried out, for example, for a period of 10 minutes, 20 minutes, 30 minutes, 40 minutes, 50 minutes, 60 minutes, 70 minutes, 80 minutes, 90 minutes, 100 minutes, 110 minutes, or 120 minutes. In the washing according to step (b), the dry matter in the washing mixture is from 0.1 wt.% to 5 wt.%, preferably from 0.5 wt.% to 3 wt.%, and particularly preferably from 1 wt.% to 2 wt.%. The dry matter in the washing mixture can be, for example, 0.1 wt.%, 0.2 wt.%, 0.3 wt.%, 0.4 wt.%, 0.5 wt.%, 1.0 wt.%, 1.5 wt.%, 2.0 wt.%, 2.5 wt.%, or 3.0 wt.%. More advantageously, the washing according to step (b) is carried out with mechanical agitation of the washing mixture. This is conveniently done by stirring or shaking the washing mixture. The washed depectinized raw material from step (b) can then be incubated in the lignin-degrading incubation solution according to step (d). Alternatively, after washing with the aqueous solution in step (b), the washed material can optionally be separated from the aqueous solution according to step (c). This separation is advantageously carried out using a decanter or a press. According to a further embodiment, the degradation of the lignin in step (d) is carried out by incubation with an alkaline incubation solution. The incubation can take place at a pH of 10 to 14, preferably from 11 to 13 and particularly preferably from 11.5 to 12. The pH therefore does not refer to the incubation solution as such, but represents the pH under which the incubation takes place. The incubation can be carried out, for example, at a pH of 10.0; 10.5; 11.0; 11.1; 11.2; 11.3; 11.4; 11.5; 11.6; 11.7; 11.8; 11.9; 12.0; 12.1; 12.2; 12.3; 12.4; 12.5; 13; 13.5 or 14. To achieve an alkaline pH, the skilled person can use any base or basic buffer solution known to them. According to another embodiment, the base is an inorganic base, preferably sodium hydroxide, calcium hydroxide, potassium hydroxide, or ammonia, although combinations of the bases can also be used. The use of ammonia as a base could further lead to amidation of the residual pectin, so that a brightened functional plant fiber with amidated pectin is ultimately obtained from the process. Particularly preferred bases are sodium hydroxide and potassium hydroxide. Advantageously, the incubation takes place at a temperature of 40°C to 95°C, preferably from 50°C to 80°C and particularly preferably from 55°C to 65°C. The incubation can for example at a temperature of 40°C, 45°C, 50°C, 55°C, 60°C, 65°C, 70°C, 75°C, 80°C, 85°C, 90°C or 95°C. Preferably, the incubation takes place over a period of 60 minutes to 48 hours, preferably from 2 hours to 24 hours and particularly preferably from 6 hours to 12 hours. The incubation can, for example, be carried out over a period of 1 h, 2 h, 3 h, 4 h, 5 h, 6 h, 7 h, 8 h, 9 h, 10 h, 11 h, 12 h, 13 h, 14 h, 15 h, 16 h, 17 h, 18 h, 19 h, 20 h, 21 h, 22 h, 23 h, 24 h, 25 h, 26 h, 27 h, 28 h, 29 h, 30 h, 31 h, 32 h, 33 h, 34 h, 35 h, 36 h, 37 h, 38 h, 39 h, 40 h, 41 h, 42 h, 43 h, 44 h, 45 h, 46 h, 47 h or 48 h. Advantageously, the suspension has a dry matter content of 0.5 wt.% to 5 wt.%, preferably 1 wt.% to 4 wt.%, and particularly preferably 1.5 wt.% to 3 wt.%. The dry matter content of the suspension can be, for example, 0.5 wt.%, 1.0 wt.%, 1.5 wt.%, 2.0 wt.%, 2.5 wt.%, 3.0 wt.%, 3.5 wt.%, 4.0 wt.%, 4.5 wt.%, or 5.0 wt.%. Preferably, the weight ratio of the base used to the dry mass of the depectinized raw material from step (a), the washed material from step (b) or the material separated from the aqueous solution from step (c) is between 0.025:1 to 0.2:1, preferably between 0.05:1 to 0.15:1 and particularly preferably between 0.06:1 to 0.125:1. During the incubation in step (d), the aqueous suspension is advantageously agitated by applying force, suitably by stirring or shaking. This is preferably done continuously to keep the particles suspended in the suspension. Advantageously, at least 25 wt.%, preferably at least 50 wt.%, particularly preferably at least 75 wt.%, and especially preferably at least 95 wt.% of the lignin in the material from steps (a), (b), or (c) is degraded by the alkaline incubation. For example, 25 wt.%, 30 wt.%, 35 wt.%, 40 wt.%, 45 wt.%, 50 wt.%, 55 wt.%, 60 wt.%, 65 wt.%, 70 wt.%, 75 wt.%, 80 wt.%, 85 wt.%, 90 wt.%, or 95 wt.% of the lignin in the material from steps (a), (b), or (c) can be degraded. During the alkaline incubation in step (d), a bleaching agent such as hydrogen peroxide can optionally be used. According to a further embodiment, the degradation of the lignin in step (d) is carried out by incubation with an enzymatic incubation solution. Advantageously, the enzymatic incubation solution comprises at least one lignin-degrading enzyme selected from the group consisting of laccase (EC 1.10.3.2), lignin peroxidase (EC 1.11.1.14), manganese peroxidase (EC 1.11.1.13), and versatile peroxidase (EC 1.11.1.16). For the purposes of the invention, lignin-degrading enzymes are enzymes that cause lignin degradation. Suitably, the incubation period is 1-10 hours, and preferably 2-5 hours. For example, the incubation period may be 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10 hours. Advantageously, the incubation takes place at a temperature of 10°C to 70°C, preferably from 20°C to 60°C, and particularly preferably from 30°C to 50°C. The incubation can be carried out, for example, at a temperature of 10°C, 15°C, 20°C, 25°C, 30°C, 35°C, 40°C, 45°C, 50°C, 55°C, 60°C, 65°C, or 70°C. Incubation can take place at a pH of between 2.0 and 10.0, preferably between 3.0 and 8.0, and particularly preferably between 4.0 and 7.0. The optimal pH depends on the particular enzyme used and its pH optimum. The pH optimum for laccase is pH 5 to 7, for lignin peroxidase pH 3 to 4.5, for manganese peroxidase pH 4 to 7, and for versatile peroxidase pH 2 to 7. Incubation can be carried out, for example, at a pH of 2.0; 2.5; 3.0; 3.5; 4.0; 4.5; 5.0; 5.5; 6.0; 6.5; 7.0; 7.5; 8.0; 8.5; 9.0; 9.5, and 10.0. Advantageously, the suspension has a dry mass of 0.5 wt% to 20 wt%, preferably 3 wt% to 16 wt%, and particularly preferably 5 wt% to 14 wt%. The dry mass in the suspension can be, for example, 0.5 wt%, 1.0 wt%, 1.5 wt%, 2.0 wt%, 2.5 wt%, 3.0 wt%, 3.5 wt%, 4.0 wt%, 4.5 wt%, 5.0 wt%, 5.5 wt%, 6.0 wt%, 6.5 wt%, 7.0 wt%, 7.5 wt%, 8.0 wt%, 8.5 wt%, 9.0 wt%, 9.5 wt%, 10.0 wt%, 10.5 wt%, 11.0 wt%, 11.5 wt%, 12.0 wt%, 12.5 wt%, 13.0 wt%, 13.5 wt%, 14.0 wt%, 14.5 wt%, 15.0 wt%, 15.5 wt%, 16.0 wt%, 16.5 wt%, 17.0 wt%, 17.5 wt%, 18.0 wt%, 18.5 wt%, 19.0 wt%, 19.5 wt% and 20.0 wt%. The aqueous suspension is advantageously set in motion during the incubation in step (d) by applying force, suitably by stirring or shaking. This is preferably carried out in a continuous manner so that the particles are kept suspended in the suspension. Advantageously, at least 25 wt.%, preferably at least 50 wt.%, particularly preferably at least 75 wt.%, and especially preferably at least 95 wt.% of the lignin in the material from steps (a), (b), or (c) is degraded by the enzymatic incubation. For example, 25 wt.%, 30 wt.%, 35 wt.%, 40 wt.%, 45 wt.%, 50 wt.%, 55 wt.%, 60 wt.%, 65 wt.%, 70 wt.%, 75 wt.%, 80 wt.%, 85 wt.%, 90 wt.%, or 95 wt.% of the lignin in the material from steps (a), (b), or (c) can be degraded. Before proceeding with the process, it may be advisable to inactivate the enzymes, for example, by heat inactivation. Methods for enzyme inactivation are known to those skilled in the art. According to a further embodiment, in step (e) of the process according to the invention, the lignin-degraded material from step (d) is separated from the lignin-degrading incubation solution by means of a decanter or a press. According to the invention, the separation of the incubation solution in step (e) is followed by a further aqueous washing step in step (f). This can serve, among other things, to wash residues of the incubation solution out of the material. For example, the pH of the material can be lowered again in the case of alkaline incubation in step (d), or enzymes can be washed out of the material in the case of enzymatic incubation in step (d). Furthermore, the lignin degradation products that were not already separated in step (e) are also removed from the material. Advantageously, the washing in step (f) is carried out with water as an aqueous solution. The use of deionized water is particularly advantageous here. In one embodiment, the aqueous solution consists of more than 50 vol% water, preferably more than 60, 70, 80, or even 90 vol%. In a preferred embodiment, the aqueous solution contains no organic solvent and, in particular, no alcohol. This results in a water-based wash and not a water-alcohol exchange as occurs in fiber washing with a mixture of alcohol and water, where this mixture contains more than 50 vol% alcohol and typically has an alcohol content of more than 70 vol%. Alternatively, a salt solution with an ionic strength of I < 0.2 mol / 1 can be used as the aqueous solution. The washing according to step (f) is advantageously carried out at a temperature of 30°C to 90°C, preferably from 40°C to 80°C, and particularly preferably from 50°C to 70°C. The washing can be carried out, for example, at a temperature of 30°C, 35°C, 40°C, 45°C, 50°C, 55°C, 60°C, 65°C, 70°C, 75°C, 80°C, 85°C, or 90°C. The contacting time in step (f) with the aqueous solution is from 10 minutes to 2 hours, preferably from 30 minutes to one hour. Washing can be carried out, for example, for a period of 10 minutes, 20 minutes, 30 minutes, 40 minutes, 50 minutes, 60 minutes, 70 minutes, 80 minutes, 90 minutes, 100 minutes, 110 minutes, or 120 minutes. In the washing according to step (f), the dry matter in the washing mixture is from 0.1 wt.% to 5 wt.%, preferably from 0.5 wt.% to 3 wt.%, and particularly preferably from 1 wt.% to 2 wt.%. The dry matter in the washing mixture can be, for example, 0.1 wt.%, 0.2 wt.%, 0.3 wt.%, 0.4 wt.%, 0.5 wt.%, 1.0 wt.%, 1.5 wt.%, 2.0 wt.%, 2.5 wt.%, or 3.0 wt.%. More advantageously, the washing according to step (f) is carried out with mechanical agitation of the washing mixture. This is conveniently done by stirring or shaking the washing mixture. According to a further embodiment, the separation of the washed material from the aqueous liquid in step (g) is carried out using a decanter or a separator, preferably a decanter. Separation using a decanter is particularly suitable given the solids load and water-binding properties. In step (h), a further washing step follows, this time with an organic solvent. This involves washing at least twice with an organic solvent. The organic solvent can also be used as a mixture of the organic solvent and water, wherein this mixture then contains more than 50 vol% of organic solvent and preferably more than 70 vol% of organic solvent. The organic solvent is advantageously an alcohol which can be selected from the group consisting of methanol, ethanol and isopropanol. The washing step in step (h) takes place at a temperature between 40°C and 75°C, preferably from 50°C to 70°C, and particularly preferably from 60°C to 65°C. Washing can take place, for example, at a temperature of 40°C, 45°C, 50°C, 55°C, 60°C, 65°C, 70°C, or 75°C. The contact time with the organic solvent in step (h) is from 60 minutes to 10 hours, preferably from 2 hours to 8 hours. Washing can be carried out, for example, for a period of 1 hour, 2 hours, 3 hours, 4 hours, 5 hours, 6 hours, 7 hours, 8 hours, 9 hours, or 10 hours. Each washing step with the organic solvent involves contacting the material with the organic solvent for a specific period of time, followed by separating the material from the organic solvent. A decanter or press is preferably used for this separation. When washing with the organic solvent in step (h), the dry mass in the washing solution is from 0.5 wt.% to 15 wt.%, preferably from 1.0 wt.% to 10 wt.%, and particularly preferably from 1.5 wt.% to 5.0 wt.%. The dry mass in the washing solution can be, for example, 0.5 wt.%, 1.0 wt.%, 1.5 wt.%, 2.0 wt.%, 2.5 wt.%, 3.0 wt.%, 3.5 wt.%, 4.0 wt.%, 5.0 wt.%, 6.0 wt.%, 7.0 wt.%, 8.0 wt.%, 9.0 wt.%, 10.0 wt.%, 11.0 wt.%, 12.0 wt.%, 13.0 wt.%, 14.0 wt.% or 15.0 wt.%. Washing with the organic solvent in step (h) is preferably carried out with mechanical agitation of the washing mixture. Preferably, washing is carried out in a container with a stirrer. During washing with the organic solvent in step (h), a device for homogenizing the suspension is advantageously used. This device is preferably a gear-type disperser. According to an advantageous embodiment, washing with the organic solvent in step (h) is carried out in a countercurrent process. According to an advantageous embodiment, the final concentration decreases during the at least two washings with an organic solvent according to step (h) The organic solvent content in the solution increases with each washing step. This incrementally increasing proportion of organic solvent reduces the water content in the fiber material in a controlled manner, ensuring that the rheological properties of the fibers are maintained during the subsequent solvent removal and drying steps, and that the activated fiber structure does not collapse. Preferably, the final concentration of the organic solvent in the first washing step is between 60 and 70 ol%, in the second washing step between 70 and 85 vol% and in an optional third washing step between 80 and 90 vol%. According to an advantageous embodiment, the process additionally comprises a comminution, grinding, or sieving step after drying in step (j). This step is advantageously designed such that, as a result, 90% of the particles have a grain size of less than 400 pm, preferably a grain size of less than 350 pm, and in particular a grain size of less than 300 pm. At this grain size, the fiber is readily dispersible and exhibits optimal swelling capacity. In a second aspect, the invention provides a brightened functional plant fiber obtainable by the production process according to the invention. The brightened functional plant fiber has a reduced lignin content due to lignin degradation. The brightened functional plant fiber accordingly has a lignin content of less than 10 wt.%, preferably less than 7.5 wt.%, and particularly preferably less than 5 wt.%, whereby the fiber is preferably obtainable by the production process according to the invention. The brightened functional plant fiber can, for example, have a lignin content of 0.5, 1, 2, 3, 4, 5, 6, 7, 8, or 9 wt.%. The reduced lignin content is associated with increased fiber stability during extended storage, as evidenced, for example, by the brightness value L*. Thus, the brightened functional plant fiber can be characterized by the fact that the brightness value L* of the brightened functional plant fiber remains essentially unchanged when the plant fiber is stored at 60°C for at least 6 weeks. In the context of the present application, the term "essentially unchanged" refers to a change in the L* value relative to the initial value of less than 5%, preferably less than 2.5%. In a third aspect, the invention provides a brightened functional plant fiber having a brightness value L* > 68, preferably L* > 84, and particularly preferably L* > 90. The brightness value L* of a plant fiber according to the invention can, for example, be greater than 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 80, 81, 82, 83, 84, 85, 86, 87, 88, 89, or 90. It is preferred if the bleached functional plant fiber is a bleached functional plant fiber selected from the group consisting of bleached apple fiber, bleached beetroot fiber, bleached pea fiber, bleached sugar beet fiber, and bleached carrot fiber. Prior art processes for producing any of the aforementioned plant fibers regularly result in dark or colored plant fibers, as the starting material either already exhibits a distinct coloration or the fibers discolor or darken during the manufacturing process. Depending on the amount used, plant fibers with a distinct coloration lead to a more or less distinct coloration of the product, which, depending on the product, can be viewed negatively from a consumer acceptance perspective.Plant fibers with a particularly high brightness make it possible to use them even where dark and / or colored fibers would lead to an undesirable color and / or browning of the product. In a further embodiment, the bleached functional plant fiber is a bleached apple fiber. The bleached apple fiber advantageously has a yield point II (rotation) in the fiber suspension of more than 0.1 Pa, preferably of 0.5 Pa and particularly preferably of more than 1.0 Pa. Advantageously, the bleached apple fiber has a yield point II (cross over) in the fiber suspension of more than 0.10 Pa, preferably of 0.5 Pa and particularly preferably of more than 1.0 Pa. The bleached apple fiber advantageously has a yield point I (rotation) in the fiber dispersion of more than 5.0 Pa, preferably of 6.0 Pa and particularly preferably of more than 7.0 Pa. Advantageously, the bleached apple fiber has a yield point I (cross over) in the fiber dispersion of more than 5.0 Pa, preferably 6.0 Pa and particularly preferably more than 7.0 Pa. The bleached apple fiber advantageously has a dynamic Weissenberg number in the fiber suspension of more than 4.0, preferably more than 5.0 and particularly preferably more than 6.0. Advantageously, the bleached apple fiber has a dynamic Weissenberg number in the fiber dispersion of more than 6.5, preferably more than 7.5 and particularly preferably more than 8.5. For the bleached apple fiber, the above-described characteristics regarding yield point and dynamic Weissenberg number can optionally be combined in any permutation. Thus, in a specific embodiment, the bleached apple fiber according to the invention can exhibit all characteristics regarding yield point and dynamic Weissenberg number. To determine the yield point I (rotation), yield point I (crossover), and the dynamic Weissenberg number in a 2.5 wt.% dispersion, the bleached apple fiber is dispersed as a 2.5 wt.% dispersion according to the method disclosed in the examples; the measurement is carried out after 1 h at 20 °C. To determine the yield point II (rotation), the yield point II (cross over) and the dynamic Weissenberg number in a 2.5 wt.% suspension, the bleached apple fiber is suspended as a 2.5 wt.% suspension according to the method disclosed in the examples, the measurement is carried out after 1 h at 20°C. The bleached apple fiber has a strength of more than 50 g, preferably more than 75 g and particularly preferably more than 100 g, wherein the bleached apple fiber is suspended in water as a 6 wt.% suspension. Advantageously, the bleached apple fiber has a viscosity of more than 100 mPas, preferably more than 200 mPas, and particularly preferably more than 350 mPas, wherein the bleached apple fiber is dispersed in water as a 2.5 wt.% dispersion and the viscosity is measured at a shear rate of 50 s -1at 20°C. Furthermore, the bleached apple fiber can preferably have a viscosity of more than 100 to 2000 mPas, and particularly preferably of 350 to 2000 mPas. The bleached apple fiber can, for example, have a viscosity of 400, 500, 600, 700, 800, 900, 1000, 100, 1200, 1300, 1400, 1500, 1600, 1700, 1800, 1900, or 2000 mPas. To determine the viscosity, the apple fiber is dispersed in demineralized water as a 2.5 wt.% dispersion using the method disclosed in the examples and the viscosity is measured at 20 °C and four shear sections (first and third section = constant profile; second and fourth section = linear ramp; measurement in each case at a shear rate of 50 s' 1) (rheometer; Physica MCR 101, measuring body CC25 (corresponds to Z3 DIN, Anton Paar, Graz, Austria). A bleached apple fiber with this high viscosity has the advantage that smaller quantities of fiber are required to thicken the final product. In addition, the fiber creates a creamy texture. The bleached apple fiber has a water-binding capacity of more than 20 g / g, preferably more than 22 g / g, particularly preferably more than 24 g / g, and especially preferably more than 27 g / g. Such an advantageously high water-binding capacity leads to high viscosity and, through this, to lower fiber consumption with a creamy texture. Advantageously, the bleached apple fiber has a moisture content of less than 15% by weight, preferably less than 8% by weight and particularly preferably less than 6% by weight. The bleached apple fiber has a pH of 3.5 to 5.0 and preferably 4.0 to 4.6 in 1.0 wt.% aqueous suspension. Advantageously, the bleached apple fiber has a grain size in which at least 90 wt.% of the particles are smaller than 400 pm, preferably smaller than 350 pm and particularly preferably smaller than 300 pm. The brightened apple fiber according to the invention is preferably in powder form. This has the advantage of providing a formulation with low weight and high storage stability, which is also easy to process. This formulation is only made possible by the apple fiber according to the invention, which, unlike modified starches, does not tend to form lumps when stirred into liquids. The bleached apple fiber has a fiber content of 80 to 95% by weight. Advantageously, the bleached apple fiber has a water-soluble pectin content of less than 10 wt.%, preferably less than 8 wt.% and particularly preferably less than 6 wt.%. The bleached apple fiber advantageously has a water-soluble pectin content of more than 0.10 wt.%, preferably more than 0.2 wt.%, more preferably more than 0.5 wt.%, and especially preferably more than 0.75 wt.%. The bleached apple fiber advantageously has a water-soluble pectin content of between 0.1 wt.% and 10 wt.%, preferably between 0.1 wt.% and 8 wt.%, and more preferably between 0.1 and 6 wt.%. The water-soluble pectin content in this apple fiber can be less than 3 wt.%, 4 wt.%, 5 wt.%, 6 wt.%, 7 wt.%, 8 wt.%, 9 wt.%, or 9.5 wt.%. The content of water-soluble pectin in this apple fiber can be, for example, 0.10 wt%, 0.2 wt%, 0.3 wt%, 0.4 wt%, 0.5 wt%, 0.6 wt%, 0.7 wt%, 0.75 wt%, 0.8 wt%, 0.8 wt%, 0.9 wt%, 1.0 wt%, 1.1 wt%, 1.2 wt%, 1.3 wt%, 1.4 wt%, 1.5 wt%, 1.7 wt%, 1.8 wt%, 1.9 wt%, 2.0 wt%, 3 wt%, 4 wt%, 5 wt%, 6 wt%, 7 wt%, 8 wt%, 9 wt% or 9.5 wt%. This residual water-soluble pectin is a highly esterified pectin. According to the invention, a highly esterified pectin is defined as a pectin with a degree of esterification of at least 50%. The residual, highly esterified pectin can preferably have a degree of esterification of more than 52.5%, 55%, 57.5%, or 60%. The degree of esterification describes the percentage of carboxyl groups in the galacturonic acid units of the pectin that are present in esterified form, e.g., as methyl ester. The degree of esterification can be determined using the JECFA method (Monograph 19-2016, Joint FAO / WHO Expert Committee on Food Additives). According to a further embodiment, the bleached functional plant fiber is obtained by the process according to the invention. In a fourth aspect, the invention relates to the use of the brightened functional plant fiber according to the invention as a thickener or structuring agent in a food product, a feed product, a beverage, a food supplement, a cosmetic product, a pharmaceutical product or a medical device. In a fifth aspect, the invention relates to a mixture comprising a brightened functional plant fiber according to the invention and a soluble pectin, which can be either a low esterified or a high esterified or low esterified amidated pectin or mixtures thereof. In a sixth aspect, the invention relates to a food product, a food supplement, a feed product, a beverage, a cosmetic product, a pharmaceutical product or a medical device produced using the brightened functional plant fiber according to the invention. Definitions A plant fiber according to the application is a component consisting primarily of fibers, isolated from a non-woody plant cell wall and consisting primarily of cellulose. The term "fiber" is somewhat misnomer because the plant fibers do not appear macroscopically as fibers, but rather as a powdered product. Other components of plant fibers include hemicellulose and pectin. According to the invention, an apple is defined as the fruit of the cultivated apple (Malus domestica). A pectin according to the application is defined as a plant polysaccharide which, as a polyuronide, consists essentially of α-1,4-glycosidically linked D-galacturonic acid units. The galacturonic acid units are partially esterified with methanol. The degree of esterification describes the percentage of carboxyl groups in the galacturonic acid units of the pectin that are present in esterified form, e.g., as methyl esters. For the purposes of the present invention, a high-esterification pectin is defined as one with an esterification degree of at least 50%. A low-esterification pectin, on the other hand, has an esterification degree of less than 50%. The esterification degree describes the percentage of carboxyl groups in the galacturonic acid units of the pectin that are present in esterified form, e.g., as methyl esters. The esterification degree can be determined using the JECFA method (Monograph 19-2016, Joint FAO / WHO Expert Committee on Food Additives). For the purposes of the invention, a bleaching agent is defined as any substance that leads to decolorization and / or brightening of fibers or the starting material. Depending on the amount used, this also includes oxidizing agents. Examples of bleaching agents include chlorine dioxide and hydrogen peroxide, which can be used alone or in combination. Generally, peroxides, such as calcium peroxide, are used as oxidizing agents. Unless otherwise stated, the L* value in the present invention refers to the L* brightness value based on the L*a*b* color space (CIElab). The L* value is determined as described in the examples. Unless explicitly stated otherwise, numerical values ​​expressed without decimal places refer to the full value, while those expressed with one decimal place refer to the full value. For example, 99% represents 99.0%. The mention of a document in this document does not constitute an admission that the said document or its contents are part of the common knowledge of the person skilled in the art. Any feature of the invention which is intended to be present in a particular range or in a particular amount may be combined in a corresponding embodiment with the other features of that embodiment, wherein the other features may be present in the ranges or amounts disclosed herein for said other features. All ranges and amounts for a feature of an embodiment can be combined with all ranges and amounts of the other features in that embodiment. For example, ranges or values ​​stated as preferred, more preferred, or most preferred for one feature or component of the invention can be combined with any range or amount stated for any other feature or component of the embodiment, regardless of whether the range or amount stated for the other element is stated as preferred, more preferred, or most preferred, etc., or is disclosed without such a statement or indication. It should also be expressly pointed out that, in the context of this patent application, indefinite articles and numerical expressions such as “one”, “two”, etc. are generally to be understood as “at least” expressions, i.e. as “at least one...”, “at least two...”, etc., unless it is expressly clear from the respective context or it is obvious or technically necessary for the person skilled in the art that only “exactly one...”, “exactly two...”, etc. can be meant. The term "comprise," as used herein, is synonymous with "contain" and does not exclude additional, unlisted elements or process steps. According to the present invention, the term "comprise" also includes the term "consist essentially of" or "consist of," that is, "comprise" is defined by the other Terms may be substituted in alternative embodiments, where "consist of" excludes any unstated element or step and "consist essentially of" allows the inclusion of additional unstated elements or steps that do not substantially affect the essential or fundamental characteristics of the composition or process in question. Where a numerical range is specified herein, that range is continuous and includes both the minimum and maximum values ​​of the range, as well as every value between those minimum and maximum values. Where a range refers to whole numbers, every whole number between the minimum and maximum values ​​of such a range is included. Where multiple ranges are specified to describe a feature or characteristic, those ranges may be combined. This means that, unless expressly stated otherwise, all ranges disclosed herein are to be understood to include all subranges contained therein. For example, a specified range of "1 to 10" is to be understood to include all subranges between the minimum value of 1 and the maximum value of 10, including the values ​​1 and 10. Example subranges of the range 1 to 10 include, but are not limited to, 1 to 6.1, 3.5 to 7.8, and 5.5 to 10.The disclosed upper and lower limits for quantity, range and ratio can be combined independently. Further advantages, special features and expedient developments of the invention emerge from the subclaims and the following representation of preferred embodiments with reference to the figures. The embodiments shown here are merely examples of the present invention and should therefore not be considered limiting. Alternative embodiments contemplated by those skilled in the art are equally encompassed within the scope of the present invention. Examples of implementation 1. Description of the manufacturing process using a rough flow chart Figure 1 schematically shows a process according to the invention for producing a brightened apple fiber as a flow diagram. Starting from a depectinized apple pomace, this is optionally washed with an aqueous solution and then optionally the aqueous solution is separated (each marked by dashed lines) or the depectinized pomace itself is used as the starting material. used. The depectinized pomace or the washed depectinized pomace or the washed, depectinized pomace separated from the aqueous solution is incubated in an alkaline incubation solution at a pH of 10-14 and a temperature of 50-80°C for 2-24 hours. The alkaline incubation solution is then separated using a decanter. The remaining material is washed again with water, and the aqueous wash solution is then separated using a solid-liquid separation. Two alcohol washing steps are then carried out, each followed by a decanter separation. In a further optional step, any residual alcohol can be removed by blowing in steam. Finally, the fibers are gently dried using a fluidized bed dryer to obtain the brightened apple fibers according to the invention. 2. Comparison of the brightness of the brightened fiber materialFigure 2 compares dried apple fibers produced according to the invention and suspensions prepared therefrom with regard to their brightness and color. For this purpose, acid-depectinized apple pomace was washed with water and the aqueous liquid was then separated off using a decanter to obtain a washed, liquid-separated, depectinized pomace with a dry matter content of 20 wt.%. This decanter output was divided into four aliquots, with the first aliquot not being treated with NaOH and the sample otherwise being subjected to the same preparation steps as the other three aliquots. The remaining three aliquots were treated with 25% (w / v) NaOH in various weight ratios for alkaline incubation: the proportion of NaOH-containing solution in the decanter extract was 2.5 wt.% in the left sample, 5.0 wt.% in the middle sample and 1.0 wt.% in the right sample.The L* value of the resulting dried apple fibers was determined as described below (see Test Method 15). The 2.5 wt.% suspension was prepared as described in Test Method 9. The first aliquot, serving as a control group, had an L* value of 64. The comparison in Figure 2 shows that with increasing amounts of NaOH, the fiber brightened to an increasing extent: from L*=68 to L*=84 to L=90. Viscosity determination revealed that all four fiber samples had a viscosity of approximately 600 mPas. Thus, alkaline brightening did not impair the functional properties, as impressively demonstrated here by the viscosity. 3. Test method for determining the yield point (rotational measurement) Measuring principle: This yield point provides information about the structural strength and is determined in the rotation test by increasing the shear stress acting on the sample over time until the sample begins to flow. Shear stresses below the yield point cause only elastic deformation, which only results in yielding at shear stresses above the yield point. In this determination, this is measured by exceeding a specified minimum shear rate V. According to the present method, the yield point T0[Pa] is at the shear rate )' > 0.1 s -1 exceeded. Measuring device: Rheometer Physica MCR series (e.g. MCR 301, MCR 101) Measuring system: Z3 DIN or CC25 Measuring cup: CC 27 P06 (ribbed measuring cup) Number of measuring sections: 3 Measuring temperature: 20 °C Measurement parameters: 1st section (rest phase): Section settings: - Default size: Shear stress - Value 0 Pa constant - Section duration: 180 s - Temperature: 20 °C Section 2 (Determination of the yield point) Section settings: - Default value: Shear stress [Pa] - Profile: Ramp log. - Starting value: 0.1 Pa - Final value: 80 Pa - Section duration: 180 s - Temperature: 20 °C Evaluation: The yield point T0 (unit [Pa]) is read in section 2 and is the shear stress (unit: [Pa]) at which the shear rate last reaches V < 0.10 s -1 amounts. The yield point measured using the rotation method is also called “yield point rotation”. The yield point II (rotation) was measured using a fiber suspension (simply stirring the fiber in with a spoon = corresponds to a non-activated fiber) and is also referred to in the context of the invention as "yield point II (rotation)." The yield point was also measured using a fiber dispersion (stirred in under the influence of high shear forces; e.g., with Ultra Turrax = corresponds to an additionally activated fiber) and is also referred to in the context of the invention as "yield point I (rotation)." 4. Test method for determining the yield point (oscillation measurement) Measuring principle: This yield point also provides information about the structural strength and is determined in the oscillation test by increasing the amplitude at a constant frequency until the sample is destroyed by the ever-increasing deflection and then begins to flow. Below the yield point, the substance behaves like an elastic solid, i.e. the elastic components (G') are higher than the viscous components (G"), while when the yield point is exceeded, the viscous components of the sample increase and the elastic components decrease. By definition, the yield point is exceeded at the amplitude when there is an equal amount of viscous and elastic components (cross over); the associated shear stress is the corresponding measured value. Measuring device: Rheometer Physica MCR series (e.g. MCR 301, MCR 101) Measuring system: Z3 DIN or CC25 Measuring cup: CC 27 P06 (ribbed measuring cup) Measurement parameters: Section settings: - Amplitude settings: Deformation - Profile: Ramp log. - Value: 0.01 - 1000% - Frequency: 1.0 Hz - Temperature: 20 °C Evaluation: Using the rheometer software Rheoplus, the shear stress at the crossover is evaluated after exceeding the linear-viscoelastic range (i.e. G' = G"). The yield point measured using the oscillation method is also called “yield point cross over”. The crossover yield point was measured using a fiber suspension (simply stirring the fiber in with a spoon = corresponds to a non-activated fiber) and is also referred to in the context of the invention as "yield point II (crossover)." The yield point was also measured using a fiber dispersion (stirred in under the influence of high shear forces; e.g., with Ultra Turrax = corresponds to an additionally activated fiber) and is also referred to in the context of the invention as "yield point I (crossover)." Measurement results and their meaning: Considering the yield point for the inventive fiber suspension stirred with a spoon (corresponding to a non-additionally activated fiber) with the inventive fiber dispersion stirred with high shear forces, e.g., Ultra Turrax (corresponding to an additionally activated fiber), one can make a statement about the advantage / necessity of activation. The measurement results are summarized in the following table. As expected, the yield point increases in each case through shear activation in the dispersion. Due to the relatively low yield point of the fiber suspension with 0H = 0.1 Pa, fiber activation is necessary for the full implementation of the fiber properties. 5. Test method for determining the dynamic Weissenberg number Measurement principle and significance of the dynamic Weißenberg number: The dynamic Weißenberg number W (Windhab E, Maier T, Lebensmitteltechnik 1990, 44: 185f) is a derived quantity in which the elastic components (G') determined in the oscillation test in the linear viscoelastic range are related to the viscous components (G"): The dynamic Weissenberg number provides a value that correlates particularly well with the sensory perception of consistency and can be considered relatively independent of the absolute firmness of the sample. A high W value means that the fibers have a predominantly elastic structure, while a low W value indicates structures with significantly viscous components. The creamy texture typical of fibers is achieved when the W values ​​are in the range of approximately 6-8; at lower values, the sample is assessed as watery (less thickened). Materials and methods: Measuring device: Rheometer Physica MCR series, e.g. MCR 301, MCR 101 Measuring system: Z3 DIN or CC25 Measuring cup: CC 27 P06 (ribbed measuring cup) Measurement parameters: Section settings: - Amplitude settings: Deformation Profile: Ramp log Value: 0.01 - 1000% Frequency: 1.0 Hz Temperature: 20 °C Evaluation: The phase shift angle δ is read in the linear-viscoelastic range. The dynamic Weissenberg number W is then calculated using the following formula: IV = ^ tan- oT Measurement results and their meaning: If one considers the dynamic Weissenberg number W for the fiber suspension according to the invention stirred with a spoon (corresponding to a fiber that has not been additionally activated) with the fiber dispersion according to the invention stirred with high shear forces, e.g. Ultra Turrax (corresponding to an additionally activated fiber), one can make a statement about the texture and also about the need for activation. The measurement results are summarized in the following table. The plant fiber according to the invention, with W values ​​of 5.0 in the suspension, is in the suboptimal range; only as a dispersion with W = 9.2 is it in the ideal range and thus only has an optimal texture in dispersed form. The results for the dynamic Weissenberg number show that activation of the fiber is necessary to achieve the desired creamy texture. 6. Test method for determining strength Implementation: The strength of the plant fiber is determined in a suspension with a fiber concentration of 6 wt.%. 150 ml of distilled water is placed in a beaker. Then, using a spoon, 9.0 g of plant fiber is stirred into the water until lump-free. This fiber-water mixture is allowed to stand for 20 minutes to swell. The suspension is transferred to a container (90 mm diameter). The strength is then measured using the following method. Measuring device: Texture Analyzer TA-XT 2 (Stable Micro Systems, Godaiming, UK) Test method / option: Measurement of force in compression direction / simple test Parameter: - Test speed: 1.0 mm / s - Travel: 15.0 mm Measuring tools: - P / 50 The strength corresponds to the force required by the measuring body to penetrate 10 mm into the suspension. This force is read from the force-time diagram. It is worth noting that, historically, the unit of strength measurement has been grams (g). 7. Test method for determining grain size In a sieving machine, a set of sieves, each with a mesh size that increases from the bottom to the top, is arranged one above the other. The sample is placed on the top sieve—the one with the largest mesh size. Sample particles with a diameter larger than the mesh size remain on the sieve; the finer particles fall through to the next sieve. The proportion of sample on the various sieves is weighed and expressed as a percentage. Implementation: The sample is weighed to two decimal places and added. The sieves are fitted with sieving aids and stacked one on top of the other with increasing mesh size. The sample is quantitatively transferred to the top sieve, the sieves are clamped, and the sieving process proceeds according to defined parameters. The individual sieves are weighed with the sample and sieving aid, as well as empty with the sieving aid. If only one limit value in the particle size range is to be tested for a product (e.g., 90% < 250 pm), only one sieve with the corresponding mesh size is used. Measurement specifications: Sample amount: 15 g Sieve aids: 2 per sieve bottom Screening machine: AS 200 digit, Retsch GmbH Screen movement: three-dimensional Vibration height: 1.5 mm Sieving time: 15 min The sieve structure consists of the following mesh sizes in pm: 1400, 1180, 1000, 710, 500, 355, 250 followed by the bottom. The grain size is calculated using the following formula: Weight in g on the sieve x 100 Share per sieve in % = - - — ; - Sample weight in g 8. Preparation of a 2.5 wt.% fiber dispersion Recipe: 2.50 g fiber 97.5 g demineralized water (room temperature) Littering time: 15 seconds The required amount of water (room temperature) is placed in a 250 ml beaker. The precisely weighed amount of fiber is slowly sprinkled directly into the stirred mixture while the stirrer (Ultra Turrax) is running at 8000 rpm (speed 1). The sprinkling time depends on the amount of fiber; it should last 15 seconds per 2.5 g of sample. The dispersion is then stirred for exactly 60 seconds at 8000 rpm (speed 1). If the sample is to be used to determine viscosity or determine the yield point I (rotation), yield point I (crossover), and dynamic Weissenberg number, it is placed in a temperature-controlled water bath at 20°C. To measure viscosity or determine the yield point I (rotation), yield point I (crossover), and dynamic Weissenberg number, the sample is carefully poured into the rheometer's measuring system after exactly 1 hour and the viscosity measurement is started. If the sample settles, it is gently stirred with a spoon immediately before filling. 9. Preparation of a 2.5 wt.% fiber suspension Recipe: 2.50 g fiber 97.50 g demineralized water (room temperature) The appropriate amount of water (room temperature) is placed in a 250 ml beaker. The precisely weighed amount of fiber is slowly sprinkled in with a plastic spoon while stirring continuously. The suspension is then stirred with the spoon until all fibers are wetted with water. If the sample is to be used for the determination of the yield point II (rotation), yield point II (crossover) and dynamic If the Weissenberg number is used, it is placed in a temperate water bath at 20°C. To measure viscosity or determine the yield point II (rotation), yield point II (crossover), and dynamic Weissenberg number, the sample is carefully poured into the rheometer's measuring system after exactly 1 hour and the viscosity measurement is started. If the sample settles, it is gently stirred with a spoon immediately before filling. 10. Test method for determining water binding capacity Implementation: The sample is allowed to swell with excess water for 24 hours at room temperature. After centrifugation and subsequent decantation of the supernatant, the water binding capacity can be determined gravimetrically in g H2O per g sample. The pH value of the suspension must be measured and recorded. The following parameters must be observed: Sample weight: Plant fiber: 1.0 g (in centrifuge tube) Added water: 60 ml Centrifugation: 4000 g Centrifugation time 10 min 20 minutes after centrifugation begins (or 10 minutes after centrifugation ends), separate the supernatant water from the swollen sample. The sample with the bound water is weighed. The water binding capacity (WBV) in g H2O / g sample can now be calculated using the following formula: 11. Test method for determining viscosity Measuring device: Physica MCR series (e.g. MCR 301, MCR 101) Measuring system: Z3 DIN or CC25 (Note: The Z3 DIN and CC25 measuring systems are identical measuring systems) Number of sections: 4 Before measurement, the sample is heated in a water bath at 20°C for at least 15 minutes. Measurement parameters: Section 1: Section settings: - Default size: Shear rate [s-1 - Profile: constant - Value: 0 s- 1 - Section duration: 60 s - Temperature: 20 °C Section 2: Section settings: - Default size: Shear rate [s -1 - Profile: linear ramp - Value: 0.1 - 100 s- 1 - Section duration: 120 s - Temperature: 20 °C Section 3: Section settings: - Default size: Shear rate [s -1 - Profile: constant - Value: 100 s- 1 - Section duration: 10 s - Temperature: 20 °C Section 4: Section settings: - Default size: Shear rate [s- 1 - Profile: linear ramp - Value: 100 - 0.1 s- 1 - Section duration: 120 s - Temperature: 20 °C Evaluation: The viscosity (unit [mPas]) is read as follows: 4th section at = 50 s - 1 12. Test method for determining the degree of esterification This method corresponds to the method published by JECFA (Joint FAO / WHO Expert Committee on Food Additives). Unlike the JECFA method, the deashed pectin is not dissolved in cold water, but heated. Isopropanol is used as the alcohol instead of ethanol. 13. Test method for determining fiber content This method is essentially identical to the method published by the AOAC (Official Method 991.43: Total, Soluble and Insoluble Dietary Fiber in Foods; Enzymatic-Gravimetric Method, MES-TRIS Buffer, First Action 1991, Final Action 1994). In this case, isopropyl alcohol was used instead of ethanol. 14. Test method for determining moisture and dry matter Principle: The moisture content of a sample is defined as the loss of mass after drying, determined under defined conditions. The moisture content of the sample is determined using infrared drying with the Sartorius MA-45 moisture analyzer (Sartorius, Göttingen, Germany). Implementation: Approximately 2.5 g of the fiber sample is weighed into the Sartorius moisture analyzer. The device settings can be found in the corresponding factory measurement instructions. The samples should be at approximately room temperature for the analysis. The moisture content is automatically displayed by the analyzer in percent [% M]. The dry matter content is automatically displayed by the analyzer in percent [% S]. 15. Test method for determining color and brightness Principle: The color and brightness measurements are performed using the Minolta Chromameter CR 300 or CR 400. The spectral properties of a sample are determined using standard color values. The color of a sample is described by its hue, brightness, and saturation. These three basic properties allow the color to be represented three-dimensionally: The hues according to the CIEIab color space are located on the outer surface of the color solid, with brightness varying along the vertical axis and saturation along the horizontal axis. When using the L*a*b* measurement system (pronounced L-star, a-star, b-star) according to the CIEIab color space, L* represents brightness, while a* and b* indicate both hue and saturation. a* and b* indicate positions on two color axes, where a* represents the red-green axis and b* the blue-yellow axis. For color measurement displays, the device converts the tristimulus values ​​into L*a*b* coordinates. Carrying out the measurement: The sample is sprinkled onto a white sheet of paper and leveled with a glass stopper. For measurement, the chromameter's measuring head is placed directly on the sample and the trigger is pressed. Triplicate measurements are taken for each sample, and the average is calculated. The L*, a*, and b* values ​​are displayed by the instrument to two decimal places. 16. Test method for the determination of water-soluble pectin in fiber-containing samples Measuring principle: Through aqueous extraction, the pectin contained in fiber-containing samples is transferred to the liquid phase. By adding alcohol, the pectin is precipitated from the extract as an alcohol-insoluble substance (AIS). Extraction: Weigh 10.0 g of the sample to be tested into a glass dish. Place 390 g of boiling distilled water into a beaker, and stir the previously weighed sample for 1 minute at the highest speed using an Ultra-Turrax. The sample suspension, cooled to room temperature, is divided into four 150 ml centrifuge beakers and centrifuged for 10 min at 4000 x g. The supernatant is collected. The sediment from each beaker is resuspended with 50 g of distilled water and centrifuged again for 10 min at 4000 x g. The supernatant is collected, and the sediment is discarded. The combined centrifuges are placed in approximately 4 l of isopropanol (98%) to precipitate the alcohol-insoluble substance (AIS). After 1 hour, the mixture is filtered through a filter cloth. and manually presses the AIS. The AIS is then placed in approximately 3 liters of isopropanol (98%) in the filter cloth and loosened by hand while wearing gloves. The pressing process is repeated, the AIS is quantitatively removed from the filter cloth, loosened and dried at 60 °C for 1 hour in a drying cabinet. The pressed, dried substance is weighed to 0.1 g to calculate the alcohol-insoluble substance (AIS). Calculation: The calculation of the water-soluble pectin based on the fiber-containing sample is carried out using the following formula, where the water-soluble pectin is obtained as alcohol-insoluble substance (AIS): AIS Tal x 100 scale in g The embodiments shown here are merely examples of the present invention and should therefore not be considered limiting. Alternative embodiments contemplated by those skilled in the art are equally encompassed within the scope of the present invention. 16. Test method for determining lignin content (Klason lignin) This method corresponds to TAPPI Test Method T222 om-88 (“Acid-insoluble lignin in wood and pulp”; In: Tappi test methods. Atlanta, GA: Technical Association of the Pulp and Paper Industry (TAPPI)). The lignin content is quantitatively determined using the Klason method, in which the polysaccharides are degraded by a two-step acid hydrolysis, and the remaining lignin residue is subsequently weighed. 17. Test method for determining lignin content (phloroglucinol) Test principle: The lignin content in plant fiber can be determined semiquantitatively by reacting with phloroglucinol (1,3,5-trihydroxybenzene) in hydrochloric acid solution (the so-called Wiesner reaction). In this reaction, the carbonyl group of the coniferyl aldehyde contained in the lignin structure reacts with the 1,3,5-trihydroxybenzene to form a purple / violet condensation product. Procedure: The substance to be tested (dried fiber sample) is sprayed with 12% hydrochloric acid. A 5 to 10 wt.% alcoholic solution of phloroglucinol is then sprayed on. The presence of lignin is indicated by a purple-red to violet color. 18. Detection of lignin degradation by the method according to the invention a) Klason-Lignin An apple fiber was subjected to bleaching using the method of the invention, and the lignin content was determined in comparison to the starting fiber according to Test Method 16. The starting fiber had a lignin content of > 10%, whereas the bleached apple fiber had a lignin content of approximately 5%. b) Phloroglucinol lignin An apple fiber was subjected to bleaching using the method according to the invention, and the lignin content was determined in comparison to the starting fiber according to Test Method 17. In parallel, wood (= positive control), apple pomace, cellulose, and hemicellulose were tested for the presence of lignin using the Wiesner reaction. The results are shown in Figure 3, with A showing the starting samples and B showing the samples after phloroglucinol addition. The untreated fiber (apple fiber AFB 200 - dark) showed a distinct red color in the phloroglucinol test, whereas this was not the case with the bleached plant fiber (apple fiber AFB 200 - dark). 19. Proof of storage stability A carrot fiber was subjected to brightening using the inventive method and stored for up to 6 weeks at temperatures of 60°C. The brightness of the fiber sample (together with the a* and b* color values) was determined weekly according to Test Method 15. The results are shown graphically in Figure 4. The starting fiber exhibited a brightness of L*= 90 at time T=0, which showed no significant reduction in the L* value upon storage for 1-4 weeks. This carrot fiber thus retained its brightness obtained according to the invention even after 6 weeks of storage and at a significantly elevated storage temperature, which can be explained by the absence of lignin.

Claims

Patent claims 1 . A process for producing a bleached functional plant fiber, the process comprising: (a) providing a depectinized raw material containing cell wall material of a plant; (b) optionally washing the depectinized raw material provided in step (a) with an aqueous solution; (c) optionally separating the washed material from step (b) from the aqueous solution; (d) degrading lignin by incubating an aqueous suspension of the depectinized raw material from step (a), the washed material from step (b) or the material separated from the aqueous solution from step (c) with a lignin-degrading incubation solution, wherein the lignin-degrading incubation solution is preferably an alkaline incubation solution and / or an enzymatic incubation solution; (e) separating the incubated material from step (d) from the lignin-degrading incubation solution; (f) washing the material separated in step (e) with an aqueous solution; (g) separating the washed material from step (f) from the aqueous solution; (h) washing the separated material from step (g) at least twice with an organic solvent and subsequently separating the washed material from the organic solvent each time; (i) optional additional removal of the organic solvent by contacting the washed material from step (h) with steam; (j) drying the material from step (h) or (i) comprising drying at normal pressure or vacuum drying to obtain the brightened functional plant fiber.

2. Process according to claim 1, characterized in that the depectinized raw material from step (a) is a residue from the processing of apples, beetroot, peas, sugar beet or carrots, preferably a residue from the pectin extraction of apples and particularly preferably a depectinized apple pomace.

3. Process according to claim 1 to 2, characterized in that the washing of the depectinized raw material in step (b) meets one or more of the following conditions: i. The aqueous solution is water, preferably deionized water or drinking water; ii. The aqueous solution is a salt solution with an ionic strength of I < 0.2 mol / l; iii. Washing is carried out at a temperature of 30°C to 90°C, preferably from 40°C to 80°C, and particularly preferably from 50°C to 70°C; iv. The contact time with the aqueous solution is from 10 min to 2 h, preferably from 30 min to 1 h; v. The dry mass in the washing mixture is from 0.1 wt% to 5 wt%, preferably from 0.5 wt% to 3 wt%, and particularly preferably from 1 wt% to 2 wt%; vi. The washing step is carried out with stirring or shaking.

4. A process according to any one of the preceding claims, characterized in that the separation of the washed material from the aqueous liquid in step (c) is carried out by means of a decanter or a press.

5. The method according to any one of the preceding claims, characterized in that the incubation in step (d) using the alkaline incubation solution satisfies one or more of the following conditions: i. the incubation takes place at a pH of 10 to 14, preferably of 11 to 13 and particularly preferably of 11.5 to 12; ii. use of a base, preferably an inorganic base, particularly preferably sodium hydroxide, calcium hydroxide, potassium hydroxide or ammonia; iii. the incubation takes place at a temperature of 40°C to 95°C, preferably of 50°C to 80°C and particularly preferably of 55°C to 65°C; iv. the incubation takes place over a period of 60 min to 48 h, preferably of 2 h to 24 h and particularly preferably of 6 h to 12 h; v. the suspension has a dry mass of 0.5 wt% to 5 wt%, preferably 1 wt% to 4 wt%, and particularly preferably 1.5 wt% to 3 wt%; vi.the weight ratio of the base used to the dry mass of the depectinized raw material from step (a), the washed material from step (b) or the material separated from the aqueous solution from step (c) is between 0.025:1 and 0.2:1, preferably between 0.05:1 and 0.15:1 and particularly preferably between 0.06:1 and 0.125:1; vii. use of a bleaching agent, which is preferably hydrogen peroxide; vii. the suspension is stirred or shaken during incubation.

6. The method according to any one of claims 1 to 4, characterized in that the incubation in step (d) using the enzymatic incubation solution fulfills one or more of the following conditions: i. the enzymatic incubation solution comprises at least one lignin-degrading enzyme, preferably selected from the group consisting of laccase (EC 1.10.3.2), lignin peroxidase (EC 1.11.1.14), manganese peroxidase (EC 1.11.1.13) and versatile peroxidase (EC 1.11.1.16); ii. the incubation takes place for a period of 1 - 10 hours and preferably from 2 to 5 hours; iii. the incubation takes place at a temperature of 10°C to 70°C, preferably from 20°C to 60°C and particularly preferably from 30°C to 50°C; iv. the incubation takes place at a pH of 2.0 to 10.0, preferably 3.0 to 8.0 and particularly preferably 4.0 to 7.0; v. the dry mass in the aqueous suspension is from 0.5 wt.% to 20 wt.%, preferably from 3 wt.% to 16 wt.%, and particularly preferably from 5 wt.% to 14 wt.%; vi. the incubation is carried out with stirring or shaking of the aqueous suspension.

7. A process according to any one of the preceding claims, characterized in that the separation of the incubated material from the lignin-degrading incubation solution in step (e) is carried out by means of a decanter or a press.

8. The process according to any one of the preceding claims, characterized in that the washing of the separated material in step (f) satisfies one or more of the following conditions: i. The aqueous solution is water, preferably deionized water; ii. The aqueous solution is a salt solution with an ionic strength of I < 0.2 mol / l; iii. The washing is carried out at a temperature of 30°C to 90°C, preferably from 40°C to 80°C and particularly preferably from 50°C to 70°C; iv. The contact time with the aqueous solution is from 10 min to 2 h, preferably from 30 min to 1 h; v. The dry mass in the washing mixture is from 0.1 wt% to 5 wt%, preferably from 0.5 wt% to 3 wt%, and particularly preferably from 1 wt% to 2 wt%; vi. the washing step is carried out with stirring or shaking.

9. A process according to any one of the preceding claims, characterized in that the separation of the washed material from the aqueous liquid in step (g) is carried out by means of a decanter or a separator, preferably by means of a decanter.

10. The process according to any one of the preceding claims, characterized in that the at least two washings with an organic solvent in step (h) meet one or more of the following conditions: i. The organic solvent is an alcohol and is preferably selected from the group consisting of methanol, ethanol, and isopropanol; 11. the washing step takes place at a temperature of 40°C to 75°C, preferably from 50°C to 70°C and particularly preferably from 60°C to 65°C; iii. the contacting time with the organic solvent takes place over a period of 60 minutes to 10 hours, preferably from 2 hours to 8 hours; iv. each washing step comprises a separation of the solid residue from the organic solvent, preferably using a decanter or a press; v. the dry mass in the washing solution is from 0.5 wt.% to 15 wt.%, preferably from 1.0 wt.% to 10 wt.% and particularly preferably from 1.5 wt.% to 5.0 wt.%; vi. the washing is carried out in a container with a stirrer, vii. during the washing a device for homogenising the suspension is used, which is preferably a gear rim disperser; viii. washing is carried out using a countercurrent process.

11. The method according to any one of the preceding claims, characterized in that during the at least two washings with an organic solvent in step (h), the final concentration of the organic solvent in the solution increases with each washing step, preferably being from 60 to 70 vol.% in the first washing step, from 70 to 85 vol.% in the second washing step, and from 80 to 90 vol.% in an optional third washing step.

12. A process according to any one of the preceding claims, characterized in that the process, after drying in step (j), additionally comprises a comprises a comminution, grinding or sieving step, whereby particles of less than 300 pm are preferably obtained.

13. Brightened functional plant fiber, characterized in that the brightened functional plant fiber has a lignin content of less than 10 wt.%, preferably less than 7.5 wt.% and particularly preferably less than 5 wt.%, wherein the fiber is preferably obtainable by a process according to one of claims 1 to 12.

14. Brightened functional plant fiber according to claim 13, characterized in that the brightness value L* of the brightened functional plant fiber remains substantially unchanged when the plant fiber is stored at 60°C for at least 4 and preferably for at least 6 weeks.

15. Brightened functional plant fiber according to claim 13 or 14, characterized in that the brightened functional plant fiber has a brightness value L* > 68, preferably L* > 84 and particularly preferably L* > 90, wherein the brightened functional plant fiber is preferably a brightened functional plant fiber selected from the group consisting of brightened apple fiber, brightened beetroot fiber, brightened pea fiber, brightened sugar beet fiber and brightened carrot fiber.

16. Brightened functional plant fiber according to claim 13 to 15, characterized in that the brightened functional plant fiber is a brightened apple fiber and has one or more of the following rheological properties: i. a yield point II (rotation) in the fiber suspension of more than 0.1 Pa, preferably 0.5 Pa and particularly preferably more than 1.0 Pa; ii. a yield point II (crossover) in the fiber suspension of more than 0.10 Pa, preferably 0.5 Pa and particularly preferably more than 1.0 Pa; iii. a yield point I (rotation) in the fiber dispersion of more than 5.0 Pa, preferably 6.0 Pa and particularly preferably more than 7.0 Pa; iv. a yield point I (crossover) in the fiber dispersion of more than 5.0 Pa, preferably 6.0 Pa and particularly preferably more than 7.0 Pa; a dynamic Weissenberg number in the fiber suspension of more than 4.0, preferably more than 5.0 and particularly preferably more than 6.0; vi.a dynamic Weissenberg number in the fiber dispersion of more than 6.5, preferably more than 7.5 and particularly preferably more than 8.5;. vii. a strength of more than 50 g, preferably more than 75 g and particularly preferably more than 100 g, wherein the bleached apple fiber is suspended in water as a 6 wt.% suspension; viii. a viscosity of more than 100 mPas, preferably more than 200 mPas, and particularly preferably more than 350 mPas, wherein the bleached apple fiber is dispersed in water as a 2.5 wt.% dispersion and the viscosity is measured at a shear rate of 50 S' 1measured at 20°C; ix. a water-binding capacity of more than 20 g / g, preferably more than 22 g / g, particularly preferably more than 24 g / g, and especially preferably more than 27 g / g; x. a moisture content of less than 15 wt.%, preferably less than 8 wt.% and particularly preferably less than 6 wt.%; xi. a pH of 3.5 to 5.0 and preferably 4.0 to 4.6 in 1.0 wt.% aqueous suspension; xii. a grain size in which at least 90 wt.% of the particles are smaller than 400 pm, preferably smaller than 350 pm and particularly preferably smaller than 300 pm; xiii. a fiber content of 80 to 95 wt.%; xiv. a water-soluble pectin content of less than 10 wt.%, preferably less than 8 wt.% and particularly preferably less than 6 wt.%.

17. Use of the brightened functional plant fiber according to any one of claims 13 to 16 as a thickener or structuring agent in a food product, a feed product, a beverage, a food supplement, a cosmetic product, a pharmaceutical product or a medical device.

18. A mixture comprising a brightened functional plant fiber according to any one of claims 13 to 16 and a soluble pectin, which may be either a low esterified or a high esterified or low esterified amidated pectin or mixtures thereof.

19. A food product, food supplement, feed product, beverage, cosmetic product, pharmaceutical product or medical device produced using the bleached functional plant fiber according to any one of claims 13 to 16.

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