METHOD AND DEVICE FOR THE INDUSTRIAL PRODUCTION OF RAPESEED OIL AND RAPESEED PROTEIN CONCENTRATE FROM RAPESEED

Description

[0001] The invention relates to a method for processing rapeseed grains, comprising the steps of: dehulling the grains, wherein the grains are passed through a roller gap between dehulling rollers, separating hulls from a low-hull grain fraction by sieving and / or air classification, such that the hulls remaining in the low-hull grain fraction make up no more than 4% by weight of the low-hull grain fraction, and pressing cold-pressed rapeseed oil from the low-hull grain fraction, wherein a water content of the low-hull grain fraction is 4 to 7% by weight, wherein a cake temperature in a resulting press cake is limited to 70°C, wherein a residual oil content is reduced to 18 to 28% by weight of a dry mass of the press cake, and wherein a portion of the press cake is returned, mixed with the low-hull grain fraction before pressing, and pressed again.

[0002] Rapeseed (Brassica napus), including so-called zero, double zero, and plus zero rapeseed varieties and canola, is the world's most commercially important oilseed after the soybean and represents a valuable raw material for the food industry, the animal feed industry, biodiesel production, and oleochemicals. In contrast to the soybean, which primarily serves as a source of vegetable protein, rapeseed is primarily cultivated for oil production. Rapeseed oil is mainly processed into biodiesel and edible oils. The extraction of rapeseed oil from rapeseed leaves a residue which, when the rapeseed oil is simply pressed, is called rapeseed cake and, after additional solvent extraction if necessary, rapeseed meal. The rapeseed meal remaining after additional solvent extraction also accounts for approximately 60% of the raw material and is therefore produced in large quantities. When used as animal feed, unlike soybean meal, it cannot be used as a sole feed.Toxins, anti-nutritional ingredients, and the high shell content preclude its use as a complete feed, as well as in the food industry, even though the rapeseed protein it contains generally has an amino acid composition that is favorable for use in human and animal nutrition. Accordingly, the market price for rapeseed meal is significantly lower than that of soybean meal. At the same time, there is a high demand for proteins suitable for nutritional purposes, especially from non-genetically modified sources. There is a great need for such proteins, for example, in fish farming in aquaculture and in poultry farming.

[0003] To make the rapeseed protein contained in the residues from rapeseed oil extraction at least usable as animal feed on an industrial scale, it is necessary to reduce or remove toxins and other harmful substances. Furthermore, the protein content should preferably be increased to the level of soybean meal and the soy protein concentrate produced from it. STATE OF THE ART

[0004] Rapeseed oil is extracted on an industrial scale using mechanical and / or chemical methods. Mechanical extraction involves hot or cold pressing the oil from the rapeseed kernels.

[0005] It is generally accepted that so-called cold-pressed rapeseed oil is produced when temperatures below 50°C are maintained during pressing. However, the Codex Alimentarius defines cold-pressed oil as meaning that no heat is applied during pressing. Using the Codex Alimentarius definition, the residual oil content of a press cake produced during rapeseed pressing can be reduced to approximately 15 percent by weight of its dry matter.

[0006] According to the Guidelines for Edible Fats and Oil, German Food Code, published by the Federal Ministry of Food and Agriculture (BMEL), cold-pressed oils require a trans fatty acid content of no more than 0.2%. Values ​​above 0.2% indicate heat damage.

[0007] By pressing at higher temperatures, although no cold-pressed rapeseed oil is produced, the residual oil content in the press cake can be further reduced.

[0008] If the rapeseed kernels are hulled before pressing to obtain a hull-free press cake, the residual oil content of the press cake is significantly higher than 15 percent by weight if only cold pressing is used due to the lack of friction from the hulls. Therefore, a first cold pressing is often followed by a second hot pressing at an elevated temperature to increase the oil yield.

[0009] Press cakes containing husks are subsequently extracted with hexane, whereby the residual oil content is reduced to less than 1 percent by weight and rapeseed meal remains, which has only a limited value.

[0010] Press cakes that remain after pressing cold-pressed oils are often not re-extracted with solvents, as this would be uneconomical for smaller oil mills due to the necessary investment costs and security requirements.

[0011] To make the oils from hot pressing or hexane extraction suitable for food use, a refining process must follow.

[0012] DE 40 41 994 A1 discloses a method and system for rapeseed dehulling, in which a combined pressure and impact treatment of the rapeseed kernels is carried out in order to reduce the hull content to less than 5%. In this known method, the following steps are carried out after cleaning the kernels: classification of the kernels and separation of undersized kernels, reduction of the kernel moisture content through drying, pressure treatment by rollers with a roller gap that is 0.2 to 0.4 times the average seed diameter, impact separation of the broken hulls from the kernels by pneumatic conveying, air separation, and separation and separation of the hulls from the kernels through electroseparation. For this purpose, in the known arrangement, a seed hopper, a scale, an iron separator, a classifying deck, a dryer, a roller peeler, a cyclone, an air classifier and an electrostatic precipitator are connected in series.Rapeseed hulling can be followed by the extraction of rapeseed oil from the kernels.

[0013] DE 40 41 994 A1 assumes that the grains reach the reduced moisture content required for dehulling by storing them for more than three months or by heating fresh rapeseed to a temperature of 95°C for drying. Long storage times require high storage capacity and corresponding investments in large storage silos, which is uneconomical and still does not ensure that the rapeseed has the appropriate moisture content for dehulling in all proportions. To maintain reproducible and consistent production, it is unavoidable to dry the seed in a controlled and reproducible manner. At 95°C, this occurs at a temperature at which the denaturation of rapeseed protein occurs; see, for example, Sofia Dahlberg's Master's thesis, Lund University, Sweden, 2017, "An investigation of rapeseed protein as a new food product."

[0014] To ensure effective dehulling, the broken shells are subsequently subjected to impact detachment. This impact detachment exerts additional pressure on the dehulled kernels, causing oil to escape from the kernels to their surface, making shell removal more difficult. As a result, a high proportion of broken kernels remain attached to the shells. Separation of the kernels from the loose shells is achieved using cyclones, air classifiers, and electroseparators, with the air classifiers separating unhulled kernels.

[0015] The actual separation of the husks is carried out by electroseparation, which has not yet been used in large-scale rapeseed processing because the required high-voltage field is associated with considerable problems and the husk separation loses its effectiveness at high throughputs.

[0016] EP 1 074 605 A1 discloses a process and a device for producing edible oil from rapeseed. The rapeseed is separated into fractions of different particle sizes by classification. The cleaned and classified rapeseed is dried at temperatures below 40°C. The dried rapeseed is crushed. The crushed rapeseed is separated into three fractions of different particle sizes, of which one fraction, called the "usable fraction," is broken down into shelled rapeseed and husks. The shelled rapeseed is moistened and then flaked. The shelled rapeseed is then cold-pressed in a press to obtain cold-pressed rapeseed oil. A filter cake resulting from filtering the cold-pressed rapeseed oil is returned to the press. The press cake resulting from pressing in the press, like the other by-products of the known process, can be used as animal feed.Alternatively, energetic use of the separated by-products, in particular the shell fractions, is proposed.

[0017] The disadvantages of this known process are that, on the one hand, the rapeseed must be dried at temperatures below 40 °C, thus requiring a large drying facility with considerable space requirements. On the other hand, the crushing of the dried rapeseed produces three fractions that must be classified. Therefore, the classification process begins again with the crushed rapeseed after cleaning.

[0018] Of the three fractions, only the hulled rapeseed from the husk is reused. All other components of the rapeseed are disposed of along with the hulls from the husk, which makes the process uneconomical, since the majority of the rapeseed is not used for oil production.

[0019] WO 2011 / 029611 A2 describes a method for processing rapeseed kernels, wherein the kernels are hulled and separated into kernels and hulls, and wherein the kernels are subjected to one or more pressings to extract the oil. The method is carried out in such a way that a solids- and oil-containing presscake remaining from the oil extraction process is dispensed, either directly or after a further milling step, as a base material, filler, or additive for human food. When dispensing a base material for human food, the hull-free presscake can be ground. The milled product can be deoiled by extraction and then used as a basis for protein concentration and / or protein isolation.

[0020] WO 2011 / 161665 A1 discloses a process for producing soy protein concentrate from white soybean flakes. The soybean flakes are extracted with hexane in a continuous hexane extractor to remove oil. After partial stripping of the hexane, the flakes are transferred to an aqueous alcohol extractor to extract the residual hexane, sugar, and other alcohol-soluble material.

[0021] US Pat. No. 4,158,656 A discloses a process for producing a detoxified protein concentrate product from defatted oilseed, particularly rapeseed. The oilseed kernels are dried to below 6% moisture, hulled, then further dried to 1 to 3% moisture, and then deoiled with hexane. The hulled and deoiled oilseed kernels are then extracted with an aqueous alcohol solvent, preferably isopropanol with added bisulfite, under non-oxidizing conditions, and the solid residue from the extraction is dried at temperatures below 60°C.

[0022] A disadvantage of this known process is that the plant cells of the hulled kernels are not broken open by pressing, which makes the oil easier and more complete to extract. Furthermore, the hexane extraction begins directly with the hulled kernels, which significantly complicates adequate deoiling and leads to long extraction times. Furthermore, high-quality cold-pressed rapeseed oil is not obtained, and the addition of an antioxidant is necessary. Cold-pressed virgin oils must not contain such additives.

[0023] EP 1 228 701 A1 discloses a process for extracting native organic substances, in particular oils, fats, waxes, dyes, vitamins, and / or other lipophilic substances and their derivatives, from native quantities of substances using centrifugal force. For this purpose, a starting product is comminuted, the lipophilic substances are extracted from the comminuted starting product using an extraction agent, and the slurry is separated in a centrifugal field into an aqueous phase containing solid components and a liquid organic phase containing the hydrophobic substances.

[0024] WO 2010 / 096943 A2 discloses a process for producing a protein preparation from rapeseed. This process comprises dehulling the rapeseed kernels, mechanical deoiling, in which only a portion of the oil is separated and which is carried out at a temperature below 80°C averaged over the duration of the pressing process, and extraction. During mechanical deoiling, which is carried out at a temperature below 80°C averaged over the duration of the pressing process, only a portion of the oil is separated. During extraction, protein impurities are removed from the protein meal. The extraction is followed by grain size adjustment to obtain a bulk material with a predetermined grain size distribution.Specifically, the known process begins with the dehulling of rapeseed kernels by pulping in a hammer mill and separating them into a kernel-rich coarse fraction and a hull-rich fine fraction in an air stream in a zigzag sifter. The kernel fraction is then cold-pressed in a screw press at temperatures between 30 and 45 °C to a residual oil content of approximately 23 percent by weight, resulting in the presscake in the form of compressed strands, called presscake pellets. The presscake pellets are deoiled with hexane in a Soxhlet apparatus to a residual oil content of less than 3%. The solvent is then removed in an air stream at room temperature. The extracted protein flour pellets thus obtained are treated with an ethanol solution in a percolation process without further comminution. The resulting finished protein concentrate is used with or without subsequent comminution.

[0025] WO 2010 / 096943 A2 assumes that the rapeseed is dried during storage at temperatures below 95 °C, preferably below 40 °C, with the goal of achieving enzyme inactivation and limited protein denaturation. However, temperatures below 40 °C trigger neither enzyme inactivation nor protein denaturation. The rapeseed grains are then separated into kernel and hull fractions in a mill, with the hulls opening by bursting rather than by deliberate breaking.

[0026] During mechanical deoiling, which is carried out at a temperature averaged over the duration of the pressing process of less than 80 °C, a limit temperature of 40 °C is exceeded in the rapeseed oil, which according to conventional opinion must be observed for good cold-pressed rapeseed oil (http: / / en.foodlexicon.org / r0000680.php).

[0027] In addition to its direct use, the press cake can be pressed into pellets at the exit of the press screw. Soft oilseeds, such as hulled rapeseed, can only be pressed slowly and with low power due to the lack of friction in the resulting press cake. If the exit of a screw press is partially closed by a pellet die, the internal pressure and resistance in the screw press increase, making it almost impossible to transport the crushed soft oilseed through the screw press's press screw. As a result, parts of the oilseed escape through the screen jacket of the screw press with the pressed oil and contaminate the oil.

[0028] As WO 2010 / 096943 A2 itself reports, discoloration becomes visible even when the presscake is pressed into pellets with a residual oil content of less than 17%, indicating significant protein denaturation. If the presscake, according to WO 2010 / 096943 A2, nevertheless has a residual oil content of only at least 10%, significant protein denaturation can be assumed.

[0029] To achieve the purity of the hulled kernels required by WO 2010 / 096943 A2 of less than 5% or 1%, significant kernel losses must be expected during air separation, as light kernels and clusters of hulls of equal weight are discharged together. The kernel fragments discharged with the hulls are no longer available for the overall process and reduce the profitability of the known process. A large-scale implementation of the known process has not yet taken place.

[0030] DE 40 35 349 A1 discloses a method and system for extracting oil from legumes and oilseeds. In this method, grains, such as rapeseed, are processed by platelet production. These platelets are moistened, expanded at 105 to 125 °C, then cooled to below 100 °C and dried, and pressed at temperatures below 100 °C to a residual oil content of 15 to 25%. A press cake resulting from pressing is extracted at temperatures of approximately 65 °C.

[0031] This well-known process starts with unhulled legumes and oilseeds. These are subjected to an expander treatment at temperatures of 105–125 °C without prior cold pressing. Only after the expanded material has cooled to 65 °C is the oil pressed. The expander thus serves the function of cell disruption through cooking to facilitate oil pressing.

[0032] The disadvantage is that this method does not allow the production of high-quality cold-pressed kernel oil from legumes and oilseeds with low shell content. Furthermore, protein denaturation occurs at the temperatures used, which complicates further purification and protein extraction.

[0033] DE 35 29 229 C1 discloses a method and apparatus for the thermal conditioning of oilseeds and oil fruits, in particular legume seeds, for the extraction of oils and fats on the one hand, and an oil- and fat-free meal suitable as animal feed on the other. Following a previous smooth rolling process, the cleaned, dried, and crushed oilseeds and oil fruits are briefly heated at superatmospheric pressure in an air- and oxygen-free atmosphere to temperatures above 105 to 148 °C and then abruptly expanded while simultaneously cooling to temperatures below 100 °C. This largely inhibits urease activity in the meal and significantly preserves the proteins as a whole and their water solubility.The well-known thermal conditioning can be performed after pressing and before extraction, where an extraction temperature of 50 to 65 °C is set. For rapeseed, it is specifically proposed to first thermally condition the smooth-rolled kernels under relatively mild conditions, then press the warm material to obtain rapeseed oil, and then thermally condition the press cake again under more elevated conditions, cool it, and finally extract it in the known manner. This should enable optimal extraction of the oil content from the husks and achieve a clear separation of pressed rapeseed oil from the kernels and extracted oil from the husks.

[0034] This well-known process uses only unhulled oilseeds. The expander replaces a pre-extraction boiling process. High-quality cold-pressed kernel oils are not obtained. The high temperatures lead to protein denaturation in rapeseed.

[0035] EP 2 783 576 A1 describes a process for producing rapeseed protein concentrate by processing rapeseed kernels. The kernels are hulled to obtain a rapeseed kernel fraction. The rapeseed kernel fraction is partially deoiled in a screw press. 5 to 60% of the resulting protein-containing presscake is recycled and mixed with the rapeseed kernel fraction upstream of the screw press to increase friction and pressure in the screw press. The remainder of the protein-containing presscake is washed with an aqueous alcohol solution to at least partially remove sugars, tannins, sinapines, and glucosinolates and to produce a rapeseed kernel protein concentrate with a residual oil content of 5 to 25% (w / w). The rapeseed kernel protein concentrate is dried at temperatures ranging from 60 to 120°C until its water content is below 10%. The rapeseed kernel fraction can be heated up to 70 °C in advance.

[0036] EP 2 783 576 A1 does not state to what extent the press cake is added directly or broken up to the rapeseed fraction and to what extent the pressing performance is thereby increased.

[0037] The proportion of hulls when pressing oil from unhulled rapeseed is approximately 15%. During pressing in a screw press, the hulls create the friction required to build up high pressure and thus achieve high pressing performance. Since EP 2 783 576 A1 specifies a hull content of 1 to 10% in the rapeseed kernel fraction, it can be concluded from the amount of recirculated presscake that increasing friction by recirculating the presscake is not very effective. The most favorable specific recirculation ratio is given as 1:0.25, with the presscake being heated to 70°C before pressing. This means that 250 kg of presscake are used for 1 ton of rapeseed kernel fraction, which corresponds to approximately 20% presscake in addition to the 1 to 10% hulls in the mass to be pressed. In other words, 20% press cake compensates for a loss of about 5 to 10% of hulls that occurs when the grains are hulled.

[0038] A disadvantage is that the constantly recirculating press cake poses a significant risk of contamination of the screw press. The temperature of the press cake remains so low that it is not pasteurized. Contamination of the screw press leads to toxin contamination of the press cake and the spread of these germs and toxins into all products of the known process.

[0039] Even if the press cake is subsequently de-polluted with alcohol-water extraction, the risk of toxin contamination remains. To eliminate contamination and toxin contamination, the screw press must be frequently cleaned and disinfected, which requires a production shutdown. This limits the industrial applicability of this known process.

[0040] Additionally, the protein content of rapeseed cake protein concentrate does not meet the definition of a protein concentrate derived from soy protein concentrate, which requires a protein content of over 60% based on dry matter. Due to the lower protein content of rapeseed cake protein concentrate, it is only a rapeseed protein flour.

[0041] From US 2019 / 0 078 115 A1 it is known to heat soybeans to 82 °C until they contain only 9% moisture, to break up the soybeans to remove hulls by suction, to roll the residues into flakes with a thickness of 1.2 to 1.6 mm, to produce collets with the aid of mechanical pressure and steam, to wash the collets with hexane to dilute the fats, to evaporate the fats by heating to 100 °C and to recuperate the fats to produce soybean oil, and to press the collets after removal of the hexane to produce a soy meal or a soy feed cake.

[0042] US Pat. No. 4,901,635 A discloses an extruder for treating high-oil material, such as certain oilseeds, which is used to prepare the material for subsequent solvent extraction of oil from the material. The material is treated with steam, pressurized, and then decompressed to atmospheric pressure. Evaporation of the moisture content results in a porous material that is well suited for solvent extraction. OBJECT OF THE INVENTION

[0043] The invention is based on the object of demonstrating a stable, reproducible and continuous process and a device for carrying it out, with which protein-containing products can be obtained from rapeseed in a cost-effective manner in addition to high-quality cold-pressed rapeseed oil, which can be further processed into high-quality feed and food, whereby large-scale implementation of the process and the device is ensured. SOLUTION

[0044] The object of the invention is achieved by a method having the features of independent claim 1 and by a device having the features of claim 12. Preferred embodiments of the method and device according to the invention are defined in the dependent claims. DESCRIPTION OF THE INVENTION

[0045] In the method according to the invention for processing rapeseed kernels, the kernels are hulled by passing them through a roller gap between hulling rollers, and hulls are separated from a low-hull grain fraction by sieving and / or air separation, such that the hulls remaining in the low-hull grain fraction make up no more than 4 percent by weight of the low-hull grain fraction. Cold-pressed rapeseed oil is pressed from the low-hull grain fraction, with a water content of the low-hull grain fraction being 4 to 7 percent by weight, a cake temperature in a resulting press cake being limited to 70°C, and a first residual oil content being reduced to 18 to 28 percent by weight of a dry mass of the press cake.Pressurized steam is added to the presscake, which is then expanded into collets. The steam is dosed so that the presscake is temporarily heated to over 100°C under the influence of the steam, and the collets have a temperature of 80°C to 95°C after expansion. The collets are extracted with an organic solvent, with a second residual oil content being reduced to 2% by weight or less of the dry mass of the collets. After expansion, a portion of the collets is recycled, blended with the low-hull grain fraction before pressing, and pressed again.

[0046] In the process according to the invention, the recirculation of a portion of the collets increases the friction of the low-shell grain fraction during pressing, thus at least significantly facilitating the limitation of the cake temperature in the resulting press cake to 70°C despite reducing the initial residual oil content to 18 to 28 percent by weight of the dry mass of the press cake. This recirculation of a portion of the press cake may also be necessary in order to be able to limit the cake temperature in the resulting press cake to 70°C despite reducing the initial residual oil content to 18 to 28 percent by weight of the dry mass of the press cake.

[0047] In the process according to the invention, the rapeseed kernels are hulled before the cold-pressed rapeseed oil is extracted. Accordingly, the press cake obtained by pressing, and the collets obtained by expanding the press cake, contain only a few hulls. This results not only in a certain improvement in the quality of the cold-pressed rapeseed oil, but also in a significant increase in the value of the collets. These collets could be used as animal feed in their own right. Heating the press cake renders them hygienically safe, yet the short heating time ensures a favorable amino acid composition with minimal undesirable denaturation.

[0048] In particular, the collets have a coherent but open structure that is favorable for their further processing, as will be explained below, and which can be maintained throughout their processing.

[0049] The process according to the invention can, if necessary, begin with cleaning the rapeseed grains to remove impurities such as stones or chaff. The thus cleaned grains can be classified according to grain size to separate grains that are not well suited for subsequent hulling. Specifically, grains smaller than a minimum size between 1.2 mm and 1.8 mm, preferably of about 1.4 mm, and larger than a maximum size between 2.6 and 3.0 mm, preferably of about 2.8 mm, can be separated. The grains exceeding the maximum size can be hulled separately using a device tailored to their grain size, and the grains with a grain size below the minimum size can be used for other purposes. Typically, the proportion of small grains is less than 8 percent by weight, often less than 4 percent by weight.

[0050] Before or after hulling, the grains are adjusted to a moisture content of between 4 and 7 percent by weight, preferably around 5 percent by weight, and dried if necessary. The drying temperature should be selected so that a grain temperature of 70 °C, preferably 65 °C, is not exceeded to prevent protein denaturation during drying. To break the hulls, the grains are passed through a nip between hulling rollers that is typically at least 20% smaller than the minimum grain size. The grains can also be passed through several nips of decreasing size in succession.

[0051] The grains crushed between the hulling rollers are then separated by sieving and / or air classification, which includes hull aspiration, into a low-hull fraction and a high-hull fraction. The hulls remaining in the low-hull fraction constitute no more than 4 percent by weight. Preferably, they do not exceed 3.5 percent by weight.

[0052] With air separation, a yield of the low-hull grain fraction of typically more than 75% and preferably around 80% can be achieved. The high-hull grain fraction is complementary to the low-hull grain fraction, so that the yield of the high-hull grain fraction is between 20% and 25% of the rapeseed input.

[0053] The shell-rich grain fraction still contains kernels, which can make up to 40 percent by weight of the shell-rich grain fraction. Therefore, it makes sense to further process the shell-rich grain fraction. This can be achieved using known methods such as oil pressing at temperatures above 90 °C or solvent extraction of the shell-rich grain fraction, particularly with hexane. Alternatively, the shell-rich grain fraction can be mixed with water at approximately 20 to 30 °C, i.e., room temperature or approximately 25 °C, which causes the fibers contained in the kernels to swell and thus flotation of the kernels to obtain another low-shell grain fraction.

[0054] Due to a different morphology, swelling does not occur in the fibers contained in the husks, or at least not to the same extent. Furthermore, the kernels differ from the husks in that they have a higher oil content. After the fibers in the kernels have swelled, the kernels have a lower density than water, while the husks continue to have a higher density than water. Accordingly, flotation of the kernels occurs. This flotation and the associated separation of kernels and husks can be assisted by introducing fine gas bubbles and / or gentle, low-shear stirring. The floated kernels are removed as the additional low-husk grain fraction. They can be dewatered using a belt press and added to the previously separated low-husk grain fraction. This addition can take place before the cold-pressed rapeseed oil is extracted, but also later.Preferably, the additional low-shell grain fraction is introduced into the main material stream before the pressurized steam is introduced and the subsequent expansion to the collets. Due to its greater density than water, the separated shell fraction can be separated, further purified, and then utilized, for example, thermally or in a biogas plant.

[0055] After hulling and before pressing, the low-hull grain fraction can be rolled into flakes and passed through at least one nip formed by flaking rollers. The temperature of the flakes must be kept below 45 °C. The flakes preferably have a flake thickness of 0.1 to 0.8 mm.

[0056] The low-hull grain fraction is pressed without the addition of additional heat. However, the work performed during pressing still causes a temperature increase. According to the invention, this temperature is limited to a maximum cake temperature of 70°C in the resulting press cake. This ensures that the trans fatty acid content of the cold-pressed rapeseed oil is reliably maintained at 0.2%, and often significantly lower.

[0057] During pressing, the cold-pressed rapeseed oil can be collected in a first oil fraction, which is heated to no more than a first limit temperature during pressing, and in a second oil fraction, which is heated to more than the first limit temperature during pressing. The first oil fraction then has the least thermal influence on its oil composition and is the highest quality rapeseed oil obtained using the process according to the invention. The second oil fraction is also high-quality cold-pressed rapeseed oil according to Codex Alimentarius. A third oil fraction can also be collected, which is heated to more than a second limit temperature during pressing. The first limit temperature between the first and second oil fractions can be between 35 and 50 °C. It is preferably approximately 40 °C.At the maximum cake temperature of 70 °C, the first oil fraction has an average temperature of 32 to 36 °C and significantly less than 0.1% trans fatty acids, while the second oil fraction has an average temperature of 40 to 50 °C and at least significantly less than 0.2% trans fatty acids. The second boundary temperature between the second and any third oil fraction can be around 60 °C.

[0058] During the pressing process according to the invention at cake temperatures of no more than 70°C, the low-hull grain fraction can be pressed to a first residual oil content of 18 to 28 percent by weight or 20 to 24 percent by weight, i.e., approximately 22 percent by weight of its dry matter. The cold-pressed rapeseed oil can be processed in the usual way by filtration and / or sedimentation and yields cold-pressed native rapeseed oils of food quality.

[0059] Conventional screw presses for oil extraction are designed for performance, meaning they aim to achieve the highest possible throughput. The dehulling of the grains and the resulting absence of hulls in the screw press result in a performance decrease, which reduces the throughput of a low-hull cold-press oil compared to a standard cold-press oil extraction process. This also increases costs because a larger screw press with higher power consumption is required. Furthermore, the higher power consumption also leads to greater heating of the material in the screw press.

[0060] In order to increase the performance of low-shell oil cold pressing with a screw press and thus improve its economic efficiency, in the process according to the invention, a portion of the press cake of the low-shell grain fraction is added before pressing in order to increase friction during pressing. This recirculation does not pose a risk of contamination of the screw press in the process according to the invention, since the recirculated portion of the press cake is only separated after expansion, and thus after the press cake has been sterilized by the added steam. In other words, the portion of the press cake recirculated according to the invention is a portion of the collets formed from it during expansion, which are free of microbial contamination and hygienically safe due to the thermal treatment. By adding the collets to increase friction during cold pressing, performance data comparable to a conventional cold oil press are achieved.In addition, the mechanical properties of the collets are more favorable for increasing the performance during pressing than those of the press cake before expansion.

[0061] It is advantageous if the returned part of the press cake or collets is cooled to a temperature of 20 to 35 °C and preferably to a temperature of 25 to 30 °C, i.e. approximately to ambient temperature, and is thus solid and less deformable, before it is added to the low-shell grain fraction.

[0062] The recycled portion of the press cake or collets has a maximum particle size of 4 to 6 mm, preferably 5 mm. This can therefore include, in particular, fine particles and fragments of the collets. Depending on the hull content, the recycled portion of the press cake or collets replaces the previously separated hulls, which is why the recycled portion can make up to 20% of the press cake or collets and thus also of the mass to be pressed. Depending on the press type, the sensibly recycled portion is more than 5% and often between 10% and 15% of the press cake or collets.

[0063] Not only the collets created directly from the press cake during expansion are suitable for recycling and increasing friction during pressing of the low-hull grain fraction. Collets remaining after extraction with an organic solvent to reduce their residual oil content are also suitable and can be sieved, dried, and recycled for pressing with a maximum size of 5 mm.

[0064] Surprisingly, the collets increase friction and thus improve the performance of pressing cold oil without reducing the quality of the pressed oil. Rather, they increase throughput and pressing performance while maintaining the same power consumption, thus limiting the cake temperature because less mechanical power is converted into heat.

[0065] The press cake obtained by pressing can be crushed or used directly, and a further low-shell grain fraction obtained by flotation or what is left over after pressing can be added to it.

[0066] The press cake is fed into an expander / extruder for steam injection and subsequent expansion. With the addition of pressurized steam, the material is compressed and briefly heated to over 100 °C, typically up to 140 °C, before expanding and cooling again as the steam releases pressure. The steam quantity must be adjusted so that the collet temperature after expansion is between 80 and 95 °C.

[0067] The resulting expanded materials are so-called collets, which, unlike pellets, in which the press cake may accrue after pressing, have an open pore structure, which facilitates their further processing. The brief temperature increase to over 100°C and up to 140°C, generated by steam and pressure, inhibits enzymes and salmonella and stabilizes the sanitized pore structure in a stable and elastic manner, thus enabling the collets to be recycled to replace the shells in the cold pressing process. In addition, the brief temperature increase leads to a partial denaturation of the proteins contained in the collets. This partial denaturation does not significantly limit the feed or food value of the proteins. Typically, the collets produced according to the invention exhibit a decrease in their protein solubility of no more than 20% compared to the press cake.However, the partial denaturation of the proteins means that during subsequent extractions of the collets to remove further oil and undesirable components, the proteins remain in the collets and are not lost. The amount of steam and the resulting temperatures are correctly adjusted if the protein denaturation of the collets is low compared to the presscake and the protein solubility, measured via NSI (Nitrogen Solubility Index) or PDI (Protein Dispersibility Index), does not fall below 80% of the protein solubility in the presscake.

[0068] The collets are extracted with an organic solvent to reduce the collets to a second residual oil content of less than 2 percent by weight or from 0.3 to 1.3 percent by weight of their dry matter. In addition to hexane, any other organic solvent in which oil dissolves well, such as isopropanol, can be used as an organic solvent. The use of azeotropic or pure alcohol in the form of ethanol is also possible. This can, in particular, be bioalcohol, so that a bioalcohol protein product is produced when processing organic rapeseed.

[0069] For the extractions, as for all previously described steps of the process according to the invention, standard industrial technologies can be used, in particular carousel extractors or belt extractors. The solvent used encloses the collets in a percolation process, forming a miscella from the solvent in which the oil contained in the collets is dissolved. This miscella is separated from the solvent by distillation in a known manner, leaving behind the oil. This oil is extracted rapeseed oil.

[0070] The extracted collets can be dried and ground to produce a high-protein rapeseed protein meal with a protein content of more than 45 percent by weight, preferably more than 48 percent by weight, in dry matter, which, like HP soybean meal, is virtually hull-free. This rapeseed meal can be further processed using known techniques.

[0071] One possible treatment of the dried collets after extraction with the organic solvent is alcohol-water extraction to remove non-proteinogenic components and enrich the proteins to a rapeseed protein concentrate.

[0072] For this purpose, the collets are first sieved to remove fine particles and collet breakage, which inevitably arise from the mechanical stress during drying. If these fine particles are used to improve the friction of the cold pressing, a sieve that retains particles of 5 mm and larger is selected. If the material is further processed in an alcoholic extraction, an exclusion limit of 1 mm is sufficient.

[0073] The collets, reduced in fines, are then subjected to swelling in the alcohol-water mixture, for which 15 minutes are sufficient. The swelling should be non-destructive before the collets, saturated with the alcohol-water mixture, are subjected to another belt extraction, which can be performed analogously to the extraction with the organic solvent. A suitable and simple implementation is to place a swelling screw upstream of the belt extraction to ensure continuous swelling. However, any other technical measures that enable continuous swelling are also suitable.

[0074] The steeping can be carried out using the alcoholic miscella from the alcoholic ribbon extraction, which would have corresponded to the distillation process. Thus, the steeping screw leads to a further extraction stage.

[0075] Alternatively, the collets extracted with the organic solvent can be further processed directly, i.e. without drying and / or crushing.

[0076] In order to avoid destroying the structure of the collets and thus creating fine particles, the collets can be dehydrated by simple drainage and allowing the organic solvent to drip off before being discharged from the solvent extractor. In this way, typically more than 50% of the solvent can be removed from the collets. At the outlet of the solvent extractor, the collets are picked up and transported away non-destructively by a conveying unit, for example a screw conveyor or a conveyor belt. The conveying unit conveys the solvent-wet collets without shearing to a filter, which is divided into separation zones. The material is transferred to the filter non-destructively. The filter can be a closed rotary filter or belt filter, in particular a vacuum belt filter.A rotary valve can be installed between the conveyor unit and the filter to separate the solvent areas. After the solvent-wet collets have been positioned on the filter, the filter is moved to a first position where the solvent content of the solvent-wet collets is further reduced. This can be accelerated by applying a vacuum to a vacuum belt filter. This allows a solvent content of less than 40% by weight to be achieved. The solvent is concentrated towards the filter due to capillary action, so that a solvent-poor layer is formed above the solvent in the capillaries in the collets, which only wets the surface of the capillaries of the collets. If the organic solvent is hexane, pure alcohol or a water-alcohol azeotrope can be applied from a second position on the filter to displace the hexane.The resulting layering of the solvents in the collets creates a nearly flat alcohol / hexane interface, resulting in only a small mixed fraction of hexane / alcohol / water. After two to three washing steps, the hexane in the collet structure is completely replaced by alcohol. This results in only small volumes of a mixed hexane / alcohol fraction, which can be separately purified by distillation. This example is exemplary. Any other technical device that allows solvent exchange can be used.

[0077] Following solvent exchange, the collets can be extracted with an aqueous alcohol solution to obtain a purified rapeseed protein concentrate. The aqueous alcohol solution can contain 70 to 96 percent alcohol by volume. 80 to 90 percent alcohol by volume is preferred. This alcohol extraction, particularly of ethanol, serves to remove toxins and other anti-nutritional ingredients. At the preferred alcohol concentration, the swelling of the fibers contained in the rapeseed material and the associated increase in volume remain low. This also prevents the percolation rates of the collets from dropping significantly as a result of swelling. Excessive swelling would close the capillaries of the collets.

[0078] Preferably, the collets are extracted with the aqueous alcohol solution in countercurrent. A solids-to-solvent ratio of 1:2 to 1:6 is appropriate. Preferably, at least 10 extraction stages are carried out in countercurrent. Towards the end of the extraction, a displacement wash with azeotropic (i.e., 96 percent) alcohol can be performed to facilitate drying of the extracted material. The extracts from the extraction stages are collected. After distilling off the alcohol, rapeseed molasses remains.

[0079] The azeotropic water-alcohol solution can be collected separately and used to exchange hexane for alcohol in the solvent exchange zone. The advantage of this is that the recovery of the alcohol-water mixture from the alcohol-water extraction does not require rectification and can therefore remain compact. Rectification, with small volumes, is reserved for solvent exchange, which separates the hexane-alcohol-water mixture.

[0080] Alcohol extraction can also be performed by creating a suspension by grinding in the aqueous alcohol solution. The suspension is then purified using countercurrent centrifuges. This can be performed as a standalone aqueous alcohol extraction or as a follow-up to an existing belt extraction. Vacuum belt extractors are also suitable for washing the alcohol from the suspension.

[0081] Suspension washing is particularly suitable for post-treatment after the intended belt extraction, as many impurities are immobilized in the collets and are only released when the collets are opened. Suspension washing thus fulfills the task of fine cleaning to increase the quality of the protein concentrate and the protein content.

[0082] The purified rapeseed protein concentrate can be dried by toasting, flash drying, or vacuum drying. The dried rapeseed protein concentrate has a protein content of over 60 percent by weight based on its dry matter.

[0083] In an apparatus according to the invention for carrying out the method according to the invention for processing rapeseed grains, comprising dehulling rollers forming a roller gap for dehulling the grains, a separating device downstream of the roller gap with at least one sieve or an air classifier for separating a low-hull grain fraction from a high-hull grain fraction, flaking rollers for rolling the low-hull grain fraction into flakes, a screw press for pressing cold-pressed rapeseed oil from the flakes, the screw press delivering a press cake, and a return device designed to return a portion of the press cake to the screw press, the screw press is followed by an expander for supplying pressurized steam to the press cake and for subsequently expanding the press cake into collets, and the expander is followed by an extractor designed toto extract the collets with an organic solvent, and the return device is designed to return the part of the press cake to the expander, i.e. in the form of a part of the collets.

[0084] Specifically, the recirculation device can be designed to separate the recirculated portion of the press cake from the collets by sieving a particle fraction with a maximum particle size in the range of 4 to 6 mm. This sieving can take place before and / or after extraction with the organic solvent in the extractor.

[0085] The return device may have a cooling system configured to cool the portion of the press cake. The cooling system may, for example, comprise a cooling air blower that cools the portion of the press cake through evaporative cooling as a result of the evaporation of the moisture contained therein.

[0086] The screw press can have a press screw rotating around a horizontal axis of rotation and a sieve shell, wherein in an oil collecting basin arranged below the sieve shell, a weir running transversely to the axis of rotation, which separates an initially pressed first oil fraction and a later pressed second oil fraction of the cold-pressed rapeseed oil from each other in the oil collecting basin, is displaceable in the direction of the axis of rotation. By displacing the weir, the above-described first limit temperature between the first and second oil fractions can be set. If a drive is provided which displaces the weir in the direction of the axis of rotation depending on a signal from at least one oil temperature sensor arranged on the weir, the first limit temperature can be regulated to a predetermined value, even if the temperature distribution across the screw press varies. The sieve shell of the screw press can be formed from strainer bars.

[0087] Furthermore, the device according to the invention can comprise a flotation tank for separating the shell-rich grain fraction into a further shell-poor grain fraction and a shell fraction by flotation in water. The flotation tank can optionally comprise a compressed air connection and / or an agitator opening at or near its bottom.

[0088] The extractor downstream of the expander can further be designed to dry the collets or to subject the still solvent-wet collets to a solvent exchange and then to extract the collets with an aqueous alcohol solution.

[0089] The number of features mentioned in the patent claims and the description is to be understood as meaning that exactly this number or a greater number than the stated number is present, without the need for the explicit use of the adverb "at least." Thus, for example, if reference is made to a screw press, this is to be understood as meaning that exactly one screw press, two screw presses, or more screw presses are present. These features may be supplemented by other features or may be the only features of which the respective product consists.

[0090] The reference signs contained in the patent claims do not represent a limitation of the scope of the subject-matter protected by the patent claims. They serve only the purpose of making the patent claims easier to understand. BRIEF DESCRIPTION OF THE CHARACTERS

[0091] In the following, the invention is further explained and described with reference to preferred embodiments shown in the figures. Fig. 1 is a block diagram of a device according to the invention and of the process according to the invention and Fig. 2 shows a preferred embodiment of a screw press of the device according to the invention. FIGURE DESCRIPTION

[0092] Fig. 1shows a block diagram of a device 1 according to the invention and, at the same time, the sequence of a method according to the invention. Rapeseed from a bunker 2 is subjected to classification and cleaning in a screening system 3. Cleaned grains 4 within a predetermined grain size range are obtained from the screening system 3. After possible drying, in order to adjust the moisture content of the grains 4 to approximately 5 percent by weight, the grains 4 are dehulled using dehulling rollers 5, which form a roller gap and are followed by a separation device. The result is a low-hull grain fraction 6 and a high-hull grain fraction 31. The low-hull grain fraction 6 is rolled into flakes using flaking rollers 7. Cold-pressed rapeseed oil 25 is pressed from the flakes in a screw press 8. The resulting press cake 9 is fed to an expander 14.

[0093] The shell-rich grain fraction 31, on the other hand, is mixed with water to form a suspension 32 in which the fibers contained in a core portion of the shell-rich grain fraction 31 swell. Flotation 33 then occurs, during which another shell-poor grain fraction 10 floats to the surface and separates from a shell fraction 11. The shell fraction 11 can be dried and / or ground and used, for example, in an incineration or biogas plant. The additional shell-poor grain fraction 10 is pressed in a belt press 12. Its solids content is added to the press cake 9 upstream of the expander 14. Water pressed from the belt press 12 is processed in an oil clarifier 13, where oil 26 is separated. The purified water is UV-treated for disinfection and reused. The press cake 9 and the further low-shell grain fraction 10 are crushed and thus fed to the expander 14.In the expander 14, the temperature of the press cake 9 is briefly increased to over 100 °C, typically up to 140 °C, by the addition of pressurized steam. Upon exiting the expander, the steam expands and cools the material emerging in the form of collets 46 to 80 to 95 °C. The collets 46 are first subjected to a solvent extraction 16 with, for example, hexane in an extractor 15. After solvent exchange 17, an aqueous alcohol extraction 18 follows. Instead of solvent exchange, drying 19 of the solvent-extracted collets can take place. This can be followed by pelletization 20 or further expansion of the dried material, or a rapeseed protein flour resulting from drying 19 is output as a product.

[0094] The alcohol extraction 18 can also be performed on collets resulting from drying 19 or on the rapeseed protein flour. In a distillation 21, rapeseed oil 27 extracted from the miscella of the solvent extraction 16 is obtained. In a distillation 22, solvent is recovered from the solvent exchange 17. A distillation 23 of the alcoholic extract from the alcohol extraction 18 results in a molasses 28. Drying 24 of the residue from the alcoholic extraction 18 yields a purified rapeseed protein concentrate 29.

[0095] A return device 34 returns a portion of the press cake 9 after expansion at the outlet of the expander 14 to the screw press 8. Specifically, fine particles are screened out of the collets 46 emerging from the expander 14, cooled to a temperature of < 35 °C using a cooling system 35 of the return device 34, and then added to the rolled, low-shell grain fraction 6 to increase the friction in the screw press 8. A certain degree of friction between the pressed, low-shell grain fraction 6 and the screw press 8 is required to achieve sufficient pressing performance in relation to the mechanical energy used, and thus also in relation to the heating of the press cake 9 produced in the screw press 8, as well as the residual oil content of the press cake 9.This friction is provided by the cooled collets without causing hygiene problems due to the return of a portion of the press cake 9 to the screw press 8, because the collets 46 are sanitized by the expansion in the expander 14. Furthermore, the collets 46 have better mechanical properties for increasing friction in the screw press 8 than the press cake 9 before the expander 14.

[0096] The Fig. 2The illustrated embodiment of the screw press 8 of the device 1 according to the invention has an electric drive 36 which rotates a press screw 37 about a horizontal axis of rotation 38 relative to a sieve jacket 39 in order to press the rapeseed oil 25 from the low-hull fraction 6, whereby the press cake 9 is formed. In the direction of the axis of rotation 38, a first oil fraction 42 is initially pressed out, in which the rapeseed oil 25 does not exceed a limit temperature. Then, a second oil fraction 43 is pressed out, which still consists of cold-pressed rapeseed oil 25 because no heat is supplied to the screw press 8. However, the action of the press screw 37 on the low-hull grain fraction 6 causes a temperature increase in the screw press 8 along the axis of rotation 38. This temperature is limited to a maximum cake temperature of the press cake 9 of 70°C. This means that the second oil fraction 43 also has a trans fatty acid content of less than 0.2%.The trans fatty acid content of the first oil fraction 42 is below 0.1%. The two oil fractions 42 and 43 are separated in an oil collecting tray 40 arranged beneath the screen jacket 39 by a weir 41 extending transversely to the rotational axis 38. The weir 41 is displaced along the rotational axis 38 by a drive 44, indicated here by a double arrow, depending on an oil temperature sensor 45 arranged on the weir 41 such that the oil temperature sensor 45 does not detect a temperature higher than the limit temperature of the first oil fraction 42. EXAMPLE

[0097] Ten tons of rapeseed, such as double-zero rapeseed, are cleaned. Depending on the degree of contamination, 2 to 3% of the original mass is removed. In subsequent classification, up to 4% of grains with a grain size of less than 1.6 mm and over 2.8 mm are removed. 94% of the original rapeseed, with a moisture content between 7 and 9%, is sent for drying.

[0098] At 60 to 70°C, the rapeseed is dried to a moisture content of 5% by weight and, after cooling to 30°C, fed to the dehulling rollers 5. Separation into the hull-rich grain fraction 31 and the hull-poor grain fraction 6 results in a yield of approximately 80% by weight of hull-poor grain fraction and 20% by weight of hull-rich grain fraction 31. The hull-rich grain fraction 31 contains 30 to 40% by weight of kernel material, while the hull-poor grain fraction 6 comprises less than 4% hull. The hull-rich grain fraction 31 contains a total of approximately 20% by weight of oil and 16% by weight of protein. The hull-rich grain fraction 31 is mixed with water at 20 to 30°C. In terms of mass fractions, this results in a ratio of 1 to 6, i.e., at least 6 kg of water are required for 1 kg of the shell-rich grain fraction 31. After adding the water, the resulting suspension 32 is agitated and mixed by gentle, shear-free stirring.For 15 minutes, the fibers of the kernels in the shell-rich grain fraction 31 swell. In the subsequent flotation 33 of the stirred shell-rich grain fraction, it is separated into the floating, further shell-poor grain fraction 10 and the shell fraction 11. To enhance the flotation, finely distributed air can be blown in. The swollen kernels of the further shell-poor grain fraction 10 are collected by the belt press 12. The water is separated and recycled to a new shell-rich grain fraction 31. The further shell-poor grain fraction 10 collected by the belt press 12 is dewatered and added to the press cake 9 upstream of the expander 14.

[0099] The low-shell grain fraction 6 is then rolled into flakes using flaking rollers 7. The low-shell grain fraction 6 is only rolled to such an extent that the flake temperature is kept below 45°C. To maintain this temperature, the flaking rollers 7 can be cooled. The flakes are fed directly to the screw press 8. In the screw press 8, the flakes are compressed by the press screw 37 of the screw press 8. The emerging cold-pressed rapeseed oil 25 is collected separately according to temperature ranges. The first oil fraction 42 with a temperature of 35 to 40°C is native, cold-pressed virgin rapeseed oil and has a trans fatty acid content of less than 0.1%. The second oil fraction 43 between 45 and 60°C is native, cold-pressed rapeseed oil 25 and has a trans fatty acid content of less than 0.2%. Both oil fractions together amount to approx.2.8 tons of cold-pressed rapeseed oil 25, with 40% virgin rapeseed oil and 60% native cold-pressed rapeseed oil. The press cake 9 emerging from the screw press 8 has a residual oil content of 22 to 23 percent by weight.

[0100] The press cake 9 is crushed, the additional low-shell grain fraction 10 from the belt press 12 is added to it, and it is fed to the expander 14. In the expander 14, the press cake is heated with the addition of pressurized steam 30 so that, after exiting the expander 14, the resulting collets 46 reach a temperature of between 80 and 95 °C. The collets 46 are cooled. Fines and fragments with a particle size of up to 5 mm are sieved off by the collets 46. The proportion of fines is 3 to 6 percent by weight. 5 to 20 percent by weight of the collets are fed to the low-shell grain fraction 6 upstream of the screw press 8 in the form of fines and fragments, increasing the friction during the cold pressing of the rapeseed oil 25.

[0101] Collets 46 larger than 5 mm are extracted in a carousel extractor of extractor 15 with hexane at 60 °C in multi-stage countercurrent percolation. The resulting miscella is distilled, and the hexane is recycled to the process. The extraction time is between 1 and 3 hours, preferably approximately 2 hours. Extracted rapeseed oil 27 with a mass of 1.1 tons is obtained.

[0102] After extraction 16, the hexane-wet collets 46 are drained and dehydrated. The collets 46 can then be either subjected to drying 19 to produce a high-protein rapeseed protein meal or to solvent exchange 17.

[0103] If drying 19 of the hexane-wet collets 46 is selected, the dried collets 46 can either be ground into a protein flour or first sieved with a 1 mm sieve to reduce the fines. The fines-free collets 46 are then fed to a swelling screw. The screw transports the collets and transfers them to the belt extractor 18 for extraction using an aqueous alcohol solution of 80% alcohol.

[0104] Solvent exchange 17 is carried out primarily with the aid of a vacuum belt filter. After further transport, the hexane contained is covered with 96 percent ethanol. The ethanol is then sucked through the collets, with the ethanol being fed in countercurrent. After three cycles, the hexane is replaced with ethanol, and the collets are then covered with 80 percent ethanol, which they swell for a swelling time of 15 minutes in countercurrent. The alcoholic solution (molasses 28) emerging from the subsequent alcohol extraction 18 can be used for swelling. The swollen material is discharged, loosened in the process, and fed to a belt extractor of the subsequent alcohol extraction 18, in which the collets are further extracted with 80 percent ethanol. The extraction time is 1 to 3 hours.The final alcohol stage can be a displacement of the alcohol-water mixture with 96% ethanol to reduce the energy costs of the subsequent drying 24. Such azeotropic alcohol can also be used to displace the hexane in the solvent exchange 17. This results in the advantage that only a small amount of solvent needs to be rectified in the distillation 22.

[0105] The alcohol from alcohol extraction 18 is distilled off and reused. Molasses 28 remains. The dry matter of molasses 28 corresponds to approximately 10 to 12% of the rapeseed used. The rapeseed protein concentrate 29 purified by alcohol extraction is dried and yields 3 tons.

[0106] Rapeseed protein concentrate 29 has the following composition: Protein content on dry matter (N*6.25) 64,0 % + / - 2 %, dry matter 90 % + / - 2 % Oil content 0,4% + / - 0,2% Glycosinolate content less than or equal to 1 µmol / g Polyphenols less than or equal to 0.1% Sinapine less than or equal to 0.1% Phytic acid 3 % + / - 2 % Light color Neutral taste Yield of concentrate based on graded rapeseed 30 %

[0107] The exemplary amino acid composition shows a composition similar to that of rapeseed: TYPICAL Amino Acids on Sample g / 100g DM on Protein g / 100g Protein Aspartic acid Asp 4,94 8,13 NE Glutamic Acid Glu 11,16 18,36 NE Hydroxyproline Hyp 0,17 0,28 NE Serine Ser 2,79 4,59 NE Glycine Gly 3,55 5,84 NE Histidine His 1,86 3,06 E Arginine Arg 4,45 7,33 (NE) Threonine Thr 2,99 4,92 E Alanine Ala 2,80 4,60 NE Proline Per 3,68 6,06 NE Tyrosine Tyr 1,60 2,63 (NE) Valine Val 3,58 5,89 E BCAA Methionine Mead 1,18 1,94 E BCAA Isoleucine Island 2,73 4,49 E Leucine Leu 4,73 7,78 E BCAA Phenylalanine Phe 2,72 4,47 E Lysine Lys 4,05 6,66 E Cysteine / Cyst Cys 1,68 2,76 (NE) Tryptophan Trp 1,03 1,69 E NE = not essential E = essential BCAA=branched chain amino acids Essential AA on AA standard 24,87 40,90 40% for Infants / children 35,26 58,00 57% BCAA 9,49 15,61 15,4%

[0108] The exemplary oil analysis shows a composition similar to that of rapeseed: LIST OF REFERENCE SYMBOLS

[0109] 1Device 2Bunker 3Screening system 4Grains 5Hulling rollers 6Low-hull grain fraction 7Flaking rollers 8Screw press 9Press cake 10Further low-hull grain fraction 11Hull fraction 12Belt press 13Oil clarifier 14Expander 15Extractor 16Solvent extraction 17Solvent exchange 18Alcohol extraction 19Drying 20Pelleting 21Distillation 22Distillation 23Distillation 24Drying 25Cold-pressed rapeseed oil 26Oil 27Extracted rapeseed oil 28Molasses 29Purified rapeseed protein concentrate 30Steam 31High-hull grain fraction 32Suspension 33Flotation 34Recirculation device 35Cooling 36Drive 37Press screw 38Rotary axis 39Screen jacket 40Oil collecting basin 41Weir 42First oil fraction 43Second oil fraction 44Drive 45Oil temperature sensor 46Collets

Claims

1. Method of processing grains (4) of a rapeseed comprising the steps of: - dehulling the grains (4), wherein the grains (4) are passed through a roller nip between dehulling rollers (5), and separating hulls from a low-hull grain fraction (6) by sieving and / or air separation such that the hulls remaining in the low-hull grain fraction (6) do not account for more than 4 % by weight of the low-hull grain fraction (6), and - pressing cold-pressed rape core oil (25) from the low-hull grain fraction (6), - wherein a water content of the low-hull grain fraction is from 4 to 7 % by weight, - wherein a cake temperature in a press cake (9) being generated is limited to 70 °C, - wherein a first residual oil content is reduced to 18 to 28 % by weight of a dry matter of the press cake, and - wherein a part of the press cake (9) is mixed with the low-hull grain fraction (6) prior to the pressing and is pressed again, characterized in - that pressurized steam (30) is supplied to the press cake (9) and that the press cake (9) is subsequently expanded to form collets (46), wherein the steam is metered such that the press case (9), under the influence of the steam (30), is temporarily heated up above 100 °C and the collets (46), after the expansion, have a temperature from 80 °C and 95 °C, - that the collets (46) are extracted with an organic solvent, wherein a second residual oil content is reduced to 2 % by weight or less of a dry matter of the collets (46), and - that the part of the press cake (9) is returned after the expansion.

2. Method of claim 1, characterized in that the part of the press cake (9) that is returned after the expansion is separated from the collets prior to and / or after the extraction wherein, optionally, the part of the press cake (9) that is returned after the expansion is separated by sieving-off smaller parts of the collets (46).

3. Method of any of the preceding claims, characterized in that the part of the press cake (9) that is returned after the expansion is cooled down to a temperature in a range from 20 to 35 °C or from 25 to 30 °C prior to being pressed again.

4. Method of any of the preceding claims, characterized in that the part of the press cake (9) that is returned after the expansion accounts for up 5 to 20 % by weight of the press cake (9).

5. Method of any of the preceding claims, characterized in that the cold-pressed rape core oil (25) is collected in a first oil fraction, that is not heated up beyond a first limit temperature during pressing, and in a second oil fraction, that is heated up to more than the limit temperature during pressing, wherein the limit temperature is between 40 and 50 °C.

6. Method of claim 5, characterized in that the low-hull fraction is pressed by means of a screw press (8) having a press screw (37) rotating about a horizontal rotation axis (38) and a sieve box (39) extending around the press screw (37), wherein, in an oil collection basin (40) arranged beneath the sieve box (39), a weir (41) running crosswise with regard to the rotation axis (38) is continuously shifted in direction of the rotation axis (38) such that it separates the first oil fraction (42) and the second oil fraction (43) of the cold-pressed rape core oil (25) in the oil collection basin (40) from one another, wherein, optionally, the weir is shifted in direction of the rotation axis (38) depending on a signal of at least one oil temperature sensor (45) arranged at the weir.

7. Method of any of the preceding claims, characterized in that the press cake (9) is broken up prior to supplying the pressurized steam (30).

8. Method of any of the preceding claims, characterized in that the organic solvent with which the collets are extracted to reduce the second residual oil content to 2 % by weight or less of the dry matter of the collets is hexane or alcohol of at least 95 %.

9. Method of any of the preceding claims, characterized in that the solvent-wet collets (46) are dried in a way conserving their porous structure, or subjected to a solvent exchange, wherein at least one exchanging solvent is used which is selected from pure alcohol and a water-alcohol azeotrope.

10. Method of any of the preceding claims, characterized in that the collets (46) that have been extracted with the organic solvent are extracted with an aqueous alcohol solution to obtain a purified rape protein concentrate (29), wherein the aqueous alcohol solution comprises 70 to 96 % by volume or 80 to 90 % by volume alcohol, wherein, optionally, the collets (46) are milled in the aqueous alcohol solution to form a suspension, and extracted in a counter-current flow.

11. Method of claim 10, characterized in that the aqueous alcohol solution is replaced by ethanol of at least 95 %.

12. Apparatus (1) for carrying out the method of processing grains (4) of a rapeseed according to any of the preceding claims, comprising - dehulling rollers (5) forming a roller nip for dehulling the grains (4); - a separation device arranged downstream of the roller nip and comprising at least one sieve or air separator for separating a low-hull grain fraction (6) from a high-hull grain fraction (31); - flaking rollers (7) for rolling the low-hull grain fraction (6) to flakes, - a screw press (8) for pressing cold-pressed rape core oil (25) from the flakes, wherein the screw press (8) puts out a press cake (9); and - a returning device (34) configured for returning a part of the press cake to the screw press (8), characterized in - that an expander (14) for supplying pressurized steam (30) to the press cake (9) and for subsequently expanding the press cake (9) to form collets (46) is arranged downstream of the screw press (8), and - that an extractor (15) which is configured for extracting the collets (46) with an organic solvent is arranged downstream of the expander, and - that the return device (34) is configured for returning a part of the press cake (9) downstream of the expander (14).

13. Apparatus (1) of claim 12, characterized in that the return device (34) is configured for separating the part of the press cake (9), in front of and / or after the extraction with the organic solvent in the extractor (15), by sieving-off a particle fraction having a maximum particle size in a range from 4 to 6 mm of the collets (46).

14. Apparatus (1) of claim 12 or 13, characterized in that the return device (34) includes a cooling (35) which is configured for cooling the part of the press cake (9).

15. Apparatus (1) of any of the claims 12 to 14, characterized in that the screw press (8) comprises a press screw (37) rotating about a horizontal rotation axis (38) and a sieve box (39), wherein a weir (41), which extends crosswise with respect to the rotation axis (38) in an oil collection basin (40) arranged below the sieve box (39) and which separates an at first pressed first oil fraction (42) from a later pressed second oil fraction (43) of the cold-pressed rape core oil (25) in the oil collection basin (40) from one another, is shiftable in direction of the rotation axis (38), wherein, optionally, a drive (44) is provided which shifts the weir (41) in the direction of the rotation axis (38) depending on a signal of at least one oil temperature sensor (45) arranged at the weir (41).