Decalcification of organic tissue

Abstract

1. A method for processing an organic feedstock comprising mineralized tissue, the method comprising: performing enzymatic hydrolysis of the organic feedstock to produce a hydrolysis fraction and a mineralized tissue residue, the mineralized tissue residue comprising a protein portion; separating the mineralized tissue residue from the hydrolysis fraction; and demineralizing the mineralized tissue residue to produce solubilized minerals and a demineralized tissue residue.

Description

[Technical field]

[0001] The present invention relates to a method for processing an organic feedstock comprising mineralized tissue, a processing plant for processing an organic feedstock comprising mineralized tissue material, and a method for demineralizing mineralized tissue. [Background technology]

[0002] Mineralized tissues are living tissues that contain minerals incorporated into an organic matrix. Mineralized tissues typically provide some form of structural support to an organism, examples include bone, fish scales, tendons, cartilage, tooth enamel, dentin, and hooves. The organic matrix typically contains proteins, thus forming the protein portion of the mineralized tissue. Taking bone as an example of a mineralized tissue, the organic matrix constitutes about 30-35% of the bone mass and is called ossein. Ossein contains roughly 95% collagen (in the form of flexible elastic fibers), which is a protein. The minerals bound in the ossein matrix are primarily calcium phosphates in a chemical arrangement known as calcium hydroxyapatite. The ossein matrix is ​​flexible, but mineralization of the matrix gives bone rigidity.

[0003] Within the biorefinery industry, there is a need to increase the percentage yield of useful end products obtained from biomass feedstocks in order to more efficiently produce greater quantities of useful products and reduce associated waste.

[0004] Due to the increasing value of meat and meat derivatives, there is a trend to scrape or mechanically separate meat from animal trimmings before they are used in biorefining processes. This reduces the quality of the feedstock available for biorefining due to the loss of protein material. In particular, the removal of meat from trimmings increases the percentage of mineral content of the trimmings, resulting in an undesirable increase in the percentage of ash in the final product. It is therefore desirable to create a process that can use this lower quality feedstock to obtain a desirable final product. Here, ash is the total mineral content determined gravimetrically (i.e., by weighing) a sample before and after heating to 550° C. for a specific period of time. The high temperature burns off all organic material, but the minerals are not destroyed by this temperature.

[0005] One example of a process used in biorefining is hydrolysis, in which chemical bonds in molecules are broken by the addition of water, typically with enzymes acting as catalysts for the reaction. As an example, proteins can be treated with hydrolysis to obtain a wide range of peptides down to single amino acids, depending on the enzymes used and the treatment conditions.

[0006] It is therefore desirable to create processes that can produce proteins, polypeptides and amino acids of sufficient quality, especially using lower quality feedstocks, including mineralized tissue.

[0007] The present inventors have recognised that biorefining processes can be improved by removing the mineralised portions of the feedstock. Summary of the Invention

[0008] According to a first aspect of the invention, a method of processing an organic feedstock comprising mineralized tissue comprises removing meat from the mineralized tissue and demineralizing the mineralized tissue residue to produce solubilized minerals and a demineralized tissue residue.

[0009] The removal of meat from calcified tissues can be carried out using several processes. Non-limiting examples include boiling or steaming (i.e., heat treatment), the use of microorganisms, the use of insects, or autolysis (without the use of additional external enzymes). One particularly advantageous process for removing meat from calcified tissues is enzymatic hydrolysis. As discussed above, in enzymatic hydrolysis, the chemical bonds in the molecules are broken by the addition of water, and the enzymes act as catalysts for the reaction. To facilitate this reaction, the various components of the reaction mixture (e.g., raw materials containing the molecules to be hydrolyzed, water, and appropriate enzymes) must be mixed together under appropriate reaction conditions. For example, enzymatic hydrolysis of organic materials can be used to obtain a wide range of peptides, down to single amino acids, depending on the enzymes and processing conditions used.

[0010] Therefore, according to a second aspect of the present invention there is disclosed a method for processing an organic feedstock comprising mineralized tissue, as set forth in claim 1. The method comprises carrying out enzymatic hydrolysis of the organic feedstock to produce a hydrolysis fraction and a mineralized tissue residue, separating the mineralized tissue residue from the hydrolysis fraction and demineralizing the mineralized tissue residue to produce solubilized minerals and a demineralized tissue residue.

[0011] Optionally, the above-mentioned process of enzymatic hydrolysis of the organic feedstock is carried out to remove meat from the mineralized tissue. The process of enzymatic hydrolysis of the organic feedstock may include the use of a protease. Optionally, the hydrolysis fraction contains the results of enzymatic hydrolysis (e.g., using a protease) primarily on meat. Proteins in protein-containing mineralized tissues may not be readily hydrolyzed because they may be shielded from the enzymatic hydrolysis process by minerals bound within the protein matrix.

[0012] The following features may be combined with each of the first and second aspects as appropriate.

[0013] Optionally, the calcified tissue residue comprises a protein portion (i.e., a portion consisting of protein) and a mineral portion. The mineral portion and the protein portion together may constitute the majority of the calcified tissue residue.

[0014] Optionally, the demineralized tissue residue comprises a protein portion, e.g., a majority of the demineralized tissue residue comprises protein.

[0015] Organic feedstocks may, for example, be derived from or include fish off-cuts (e.g., salmon or cod), or chicken off-cuts, or meat off-cuts, including other animal origins. In particular, organic feedstocks may be derived from waste products generated by the food industry, or may be a secondary product of another industrial process. Organic feedstocks may include "industrial fish", i.e. raw materials used to produce fishmeal. Processing may therefore help to utilise discarded products and minimise waste.

[0016] Depending on the organic feedstock, the mineralized tissue present in the organic feedstock may include one or more of bone, fish scales, tendons, cartilage, tooth enamel, dentin, and hoof. Preferably, the mineralized tissue includes bone. The organic feedstock may include meat and bone from an aquatic animal source (e.g., from a marine animal) or a terrestrial animal source.

[0017] The mineralized tissue within the organic feedstock may comprise a protein portion and a mineral portion. If the mineralized tissue is bone, the mineral portion of the mineralized tissue may comprise calcium hydroxyapatite. If the mineralized tissue is bone, the protein portion may comprise ossein (which comprises primarily collagen).

[0018] Optionally, the treatment of the organic feedstock is carried out as a continuous flow (i.e., non-batch) process.

[0019] Reference to a continuous flow process is intended to encompass processes in which at least some flow of material through a process stage occurs in a single pass without batchwise processing, with the reaction mixture continuously entering the processing plant and the product of the reaction continuously exiting the processing plant (primary continuous flow process). Depending on the nature of the reaction, further raw materials may be added continuously during the process and / or products may be continuously removed during the process. In some cases, a portion of the material may be removed from the primary continuous flow process and processed in a secondary continuous flow process, and then a portion of the material produced in the secondary continuous flow process may be reintroduced into the primary continuous flow process.

[0020] Thus, additional organic feedstock may be provided early in the enzymatic hydrolysis process to replenish the volume of reactants within the process as the hydrolyzed fraction and mineralized tissue residue exit the enzymatic hydrolysis process. Similarly, the volume of reactants within a demineralization process may be replenished by mineralized tissue residue entering the demineralization process as solubilized minerals and demineralized tissue residue exit the demineralization process.

[0021] By using a continuous flow process (non-batch process), the processing of organic feedstocks can be more efficient and streamlined than the corresponding batch-based system. In general, a continuous flow process requires less downtime of the vessels used for each processing step and the associated machinery used to carry out the reaction during batch changeover, e.g., pumps. Time lost during batch changeover is also avoided. Energy input and operating personnel or equipment required to carry out batch changeover are also avoided.

[0022] The method may include heating the material discharged from the enzymatic hydrolysis process (i.e., the hydrolysis fraction and the calcified tissue residue) to a temperature sufficient to inactivate (deactivate / denaturate) the enzyme. In one non-limiting example, the material may be heated to about 95° C. for about 10 minutes. The temperature to which the material is heated (and the time it is held at that temperature) may be appropriately selected depending on the enzyme used.

[0023] Decalcification of the calcified tissue residue is discussed in more detail below, but before that discussion, a brief discussion of the processing of the hydrolyzed fraction is provided.

[0024] The output from the hydrolysis of an organic feedstock may comprise a hydrolysis fraction and a calcified tissue residue, wherein the hydrolysis fraction comprises the following fractions: an aqueous fraction comprising water with dissolved proteins, polypeptides and amino acids (the aqueous fraction may be called a hydrolysate); - a sediment fraction containing, for example, insoluble proteins and other small solids (the sediment fraction may typically contain 30-40% dry matter); and an oil fraction.

[0025] These first two (the aqueous fraction and the sediment fraction) may be referred to together as the "slurry fraction."

[0026] The hydrolysis fraction (including the aqueous fraction, the sediment fraction, and the oil fraction) may be separated into three component fractions. For example, a three-phase decanter (optionally a centrifugal decanter) may be used. Other separator configurations are also possible, for example a combination of a two-phase decanter with one or two separators.

[0027] Each of the aqueous, sediment, and oil fractions, once separated, may be further processed, for example, each may undergo further separation using, for example, one or more centrifuges and / or one or more filters (e.g., molecular sieves or mechanical filters).

[0028] The aqueous fraction may be dried. The precipitate fraction may be dried. The aqueous and precipitate fractions need not be completely dried, but may be partially dried. The aqueous and precipitate fractions may be dried to the extent that they are in a form that is stable according to their water activity. For example, the aqueous fraction may be partially dried to form a paste, usually with a dry matter content of more than 60%.

[0029] An evaporator may be used to partially dry the aqueous fraction (to form a paste). A dryer may be used to completely dry the aqueous fraction (to form a meal). In general, it is not energy intensive (and therefore low cost) to first partially dry the aqueous fraction (to form a paste) using an evaporator and then transfer the paste to a dryer to completely dry the paste. Thus, drying the aqueous fraction may be a two-step process that includes first partially drying the aqueous fraction (in an evaporator) to form a paste and then completely drying the paste (in a dryer) to form a meal.

[0030] A spray dryer may be used to form a powder from the paste. The paste received by the spray dryer should typically contain 30-50% dry matter, somewhat depending on particle size and viscosity. If the spray dryer is not co-located with the evaporator, the evaporator should produce a paste with more than 60% dry matter (for the paste to be microbiologically stable), then water must be added back to the paste before injection into the spray dryer.

[0031] Correspondingly, the precipitate fraction may also be partially or completely dried. Since the precipitate fraction has physical properties that make it difficult to process in a conventional evaporator, a dryer may be used to partially or completely dry the precipitate fraction.

[0032] Generally, a paste has a dry matter content of more than 60% and a meal has a dry matter content of more than 92%.

[0033] Optionally, demineralizing the calcified tissue residue comprises treating the calcified tissue residue with an acid solution to solubilize minerals, the acid solution dissolving ions in the calcified portion of the calcified tissue residue and leaving the protein portion of the calcified tissue residue in the form of a demineralized tissue residue.

[0034] Optionally, the acid solution includes hydrochloric acid (HCl).

[0035] The acid solution may alternatively or additionally contain other strong acids. Examples of such strong acids include sulfuric acid (H2SO4), nitric acid (HNO3), and phosphoric acid (H3PO4). In general, the stronger the acid, the more effective it is at demineralizing calcified tissue residues.

[0036] HCl has been found to have a favorable dissociation constant and is more economically viable than other acids. The use of HCl is also more practically viable and presents lower health and safety risks and associated costs of using strong acids.

[0037] Optionally, the acid solution comprises an acid at a concentration of 1-5% by weight.

[0038] Optionally, the concentration of the acid is 1-4% by weight, or 2-3% by weight. Preferably, the concentration of the acid is approximately 3% by weight.

[0039] The concentration of the acid may depend on the composition of the mineralized tissue residue and therefore on the type of organic feedstock used. The concentration of the acid may also depend on the type of acid used. The concentration of the acid should be high enough so that the rate of the demineralization reaction is not unduly inhibited by the lack of acidic reactant, but not so high that unreacted acid is wasted. Both of these factors increase the economic efficiency of the demineralization process.

[0040] Optionally, the weight ratio of the calcified tissue residue to the acid solution is 1:2 to 1:8. Optionally, the weight ratio of the calcified tissue residue to the acid solution is 1:3 to 1:5. Optionally, the weight ratio of the calcified tissue residue to the acid solution is approximately 1:5. Thus, the weight of the acid solution is large compared to the weight of the calcified tissue residue. This ensures that the acid solution encompasses all of the calcified tissue residue during decalcification, so that the rate of reaction is not limited by lack of contact between the acid and the calcified tissue residue. The weight percentage of the acid solution is limited for spatial and economic efficiency, as well as to limit the amount of acid solution that remains unreacted (which may then be considered useless). The lower the percentage of acid solution used, the greater the volume of calcified tissue residue that can be processed in the same volume of container.

[0041] Optionally, demineralizing the mineralized tissue residue includes adding acid in stages to control the demineralization rate. Thus, the concentration of reactive acid can be controlled during the demineralization process. Reactive acid is acid that has not yet been consumed after reacting with the mineral of the mineralized tissue residue, which still has the potential to cause a reaction with the mineral to separate the mineral from the protein portion of the mineralized tissue residue. The acid is consumed as it reacts with and solubilizes the mineral content of the mineralized tissue residue. Additional acid solution can be added during the demineralization process to maintain a desired reaction rate. This can reduce the amount of time it takes to achieve a desired level of demineralization.

[0042] Optionally, demineralization of the calcified tissue residue is performed for between 30 and 180 minutes. Optionally, demineralization of the calcified tissue residue is performed for between 60 and 120 minutes. Optionally, demineralization of the calcified tissue residue is performed for approximately 60 minutes.

[0043] When the demineralization process is carried out in a continuous flow process, the length of time that the demineralization is carried out depends on the residence time of the mineralized tissue residue in the demineralization reaction vessel. In the demineralization reaction vessel, the reactants generally traverse a path that moves in a direction from the inlet to the outlet. The residence time of the mineralized tissue residue in the reaction vessel can be controlled by varying the length of the path between the inlet and the outlet of the reaction vessel through which the mineralized tissue residue must travel. Thus, the length of the reaction vessel can affect the duration of the demineralization process. The rate at which the mineralized tissue residue moves through the reaction vessel can also affect the duration of the demineralization process. The length of time of the demineralization process should be sufficient to solubilize substantially all of the mineral portion of the mineralized tissue residue, but not so long that energy is wasted by unnecessarily maintaining the completely demineralized tissue residue in the demineralization reaction vessel.

[0044] Optionally, demineralization of the calcified tissue residue is performed at a temperature between 30 and 70 degrees Celsius. Optionally, demineralization of the calcified tissue residue is performed at a temperature between 40 and 55 degrees Celsius. Optionally, demineralization of the calcified tissue residue is performed at a temperature of approximately 40 degrees Celsius. Thus, the temperature at which demineralization is performed is advantageously increased to provide energy to the reactants to increase the reaction rate without damaging the reactants or products, and without wasting energy or other resources by raising the temperature unnecessarily high.

[0045] Optionally, the demineralized tissue residue undergoes a further enzymatic hydrolysis process. The demineralized tissue residue formed by demineralization of the mineralized tissue residue comprising a protein portion may also comprise a protein portion. The enzymatic hydrolysis of the demineralized tissue residue results in at least a portion of the protein portion of the demineralized tissue residue being hydrolyzed. Optionally, the enzymatic hydrolysis of the demineralized tissue residue comprises the use of a protease.

[0046] This second hydrolysis process may have an enhanced effect compared to the effect of hydrolysis on mineralized tissues (demineralized tissues are more easily hydrolyzed due to the lack of minerals acting as a barrier to the reaction between proteins and enzymes). Thus, the yield of proteins / polypeptides / amino acids from organic feedstocks may be increased. The mineralized tissue residue contains protein moieties that are possible but not readily achievable to process via further enzymatic hydrolysis in which the protein is broken down into its hydrolytic components. The demineralized tissue residue may contain protein moieties that are easily achievable to process via further enzymatic hydrolysis in which the protein is broken down into its hydrolytic components.

[0047] The method may include heating the material discharged from the further enzymatic hydrolysis process to a temperature sufficient to inactivate (deactivate / denaturate) the enzyme. In one non-limiting example, the material may be heated to about 95° C. for about 10 minutes. The temperature to which the material is heated (and the time it is held at that temperature) may be appropriately selected depending on the enzyme used.

[0048] In any of the processes described above, or any of the processes described below, the solubilized minerals can be separated from the demineralized tissue residue and collected for further processing and / or further use, for example, for use in a nutritional supplement or fertilizer.

[0049] The process may further include recovering the solubilized minerals, for example, by neutralization. The solubilized minerals may be neutralized, for example, using sodium hydroxide (NaOH) or potassium hydroxide (KOH). The neutralized solution may be centrifuged or filtered such that the precipitated minerals are collected to form a mineral slurry or mineral solids.

[0050] The mineral slurry may typically include calcium phosphate (CaPO4) slurry. The neutralization process is used for recovery of the CaPO4 solids, for example, for reuse as an ingredient in nutritional supplements or fertilizers. This maximizes raw material usage by using both the protein and mineral portions, thereby limiting overall waste in the process. By centrifuging the neutralized solution, the precipitated minerals can be effectively collected, as the centrifugal force aids in the separation of solids from the liquid.

[0051] Alternatively, the mineral slurry can be collected from the neutralized solution using a filter press, such as a plate and frame filter press, a membrane filter press, an automatic filter press, or a concave plate filter press, or using a drum filter, such as a rotary vacuum drum filter.

[0052] In any of the processes described above, or in any of the processes described below, the demineralized tissue residue may be dried. Drying the demineralized tissue residue makes it possible to collect a protein-rich product comprising the proteins that make up the protein portion of the mineralized tissue residue, which may be advantageously utilized in further processes or products. When the mineralized tissue residue comprises bone, the protein-rich product comprises mainly collagen.

[0053] An evaporator may be used to partially dry the demineralized tissue residue (to form a paste). A dryer may be used to completely dry the demineralized tissue residue (to form a meal). Drying the demineralized tissue residue may be a two-step process involving first partially drying the demineralized tissue residue (in an evaporator) to form a paste, and then completely drying the paste (in a dryer) to form a meal.

[0054] Generally, a paste has a dry matter content of more than 60% and a meal has a dry matter content of more than 92%.

[0055] Nitrogen is present in the product of the hydrolysis reaction from amino acids present mainly in proteins and peptides. Therefore, the protein content of the collected product can be determined by measuring the nitrogen content. Typically, a crude protein value is used to demonstrate the protein content of a sample, and this value is calculated by multiplying the nitrogen content (g / 100g, or %) (analyzed using the Kjeldahl method or by combustion analysis according to Dumas's principle) by a factor of 6.25.

[0056] The following discussion provides five examples of processes used to target different end products.

[0057] Optionally, in a first process, the method includes dividing the mineralized tissue residue into a first portion that is not demineralized and a second portion that is demineralized, and after demineralization of the second portion of the mineralized tissue residue, separating the solubilized minerals from the demineralized tissue residue, and drying the demineralized tissue residue together with the first portion of the mineralized tissue residue.

[0058] Thus, a first portion of the mineralized tissue residue may be dried without undergoing a demineralization process. The size of the first portion may be selected to target a particular ash content in the final product. The motivation may be related, for example, to economics (yield) or product quality (e.g., calcium content, or total ash content).

[0059] Splitting the calcified tissue residue into a first and a second part can be achieved using a flow splitter. The flow splitter can be provided by a combination of a screw conveyor and a rotary dosing valve. The calcified tissue residue can move along a screw conveyor (optionally with the screw conveyor arranged substantially horizontally or at a small angle to the horizontal) under which the rotary dosing valve is mounted. A part of the calcified tissue residue can be diverted from the main flow by the rotary dosing valve, while the rest of the calcified tissue residue is transported further by the conveyor. The flow splitter thus splits the flow of the calcified tissue residue into two parts in a non-selective manner. The relative sizes of the two split flows can be set by the rotation speed of the rotary dosing valve.

[0060] Optionally, in the second process, the method comprises separating the solubilized mineral from the demineralized tissue residue and carrying out a second enzymatic hydrolysis process on the demineralized tissue residue. The demineralized tissue residue undergoes a further enzymatic hydrolysis process, where the hydrolysis may have an enhanced effect compared to the effect of hydrolysis on mineralized tissue (the demineralized tissue is more easily hydrolyzed (compared to mineralized tissue) due to the lack of mineral acting as a barrier to the reaction between proteins and enzymes). Thus, the yield of proteins / polypeptides / amino acids from the organic feedstock can be increased. By using a separate processing stage, i.e., reaction vessel, for the hydrolysis of the demineralized tissue residue, the parameters of the reaction can be more specifically adjusted for the demineralized tissue residue, compared to, for example, feeding the demineralized tissue residue back to the organic feedstock for the hydrolysis process in the first hydrolysis stage.

[0061] By removing the mineral part, the protein fraction of the final product is increased, which means that the final product is purer and more refined due to the reduced mineral content. This means that further purification to reduce the ash content may no longer be required to achieve a given quality of the product. Because of these advantages, performing a de-ashing process following the hydrolysis process and before the further hydrolysis process allows the use of lower quality raw materials. Lower quality raw materials may be, for example, fish or other animal bones that have been scraped or otherwise processed to remove meat from the bone. The use of the method may ensure that using this lower quality raw material is still viable without the final product falling below the required quality. As a result, the method reduces waste by using lower quality raw materials that would otherwise be discarded.

[0062] Optionally, in a third process, the method further comprises separating the solubilized minerals from the demineralized tissue residue and recycling the demineralized tissue residue back into the organic feedstock for enzymatic hydrolysis.

[0063] The demineralized tissue residue undergoes a further enzymatic hydrolysis process, where hydrolysis may have an enhanced effect compared to the effect of hydrolysis on mineralized tissues due to the lack of inorganic matter acting as a barrier to the reaction between proteins and enzymes. Thus, the yield of proteins / polypeptides / amino acids from organic feedstocks can be increased. By recycling the demineralized tissue residue back into the organic feedstock, the demineralized tissue residue can undergo further hydrolysis reactions without the need to set up a further separate processing step. Thus, this method reduces the number of space, machinery and reactant resources that would otherwise be required if a second hydrolysis processing step were used.

[0064] The demineralized tissue residue may be treated (e.g., by sieving) before being reintroduced into the organic feedstock, so that only residues above a certain size are recycled. Generally, from a product quality or process control standpoint, too much recycling of the same material is not advantageous.

[0065] By recycling the demineralized tissue residue back to the beginning of the process, demineralized tissue residue that was not completely hydrolyzed during the second hydrolysis process can be recycled back into the organic feedstock and may undergo a third hydrolysis process, repeated until the tissue is completely hydrolyzed or small enough to be removed during a process to remove tissue smaller than a certain size (e.g., sieving). Thus, a more complete hydrolysis can be performed, further increasing the yield of proteins / polypeptides / amino acids.

[0066] The above discussion regarding the advantages of carrying out a demineralization process following the hydrolysis process and prior to a further hydrolysis process also applies when the demineralized tissue residue is returned to the organic feedstock for further hydrolysis.

[0067] Optionally, in a fourth process, the method further comprises separating the solubilized minerals from the demineralized tissue residue and partially drying the demineralized tissue residue to form a protein paste.

[0068] The demineralized tissue residue can be dried and collected in the form of a protein meal, and thus incorporated into the final product protein meal by drying, without undergoing a further hydrolysis process.

[0069] Optionally, in a fifth process, the method includes separating the solubilized minerals from the demineralized tissue residue, performing a second enzymatic hydrolysis process on the demineralized tissue residue, and separating the output of the second enzymatic hydrolysis process into a second precipitate fraction and a second aqueous fraction. The method may include drying the second precipitate fraction. The method may include evaporating liquid from the second aqueous fraction to form a peptide paste, and optionally spray drying a portion of the peptide paste to form a peptide powder.

[0070] The solubilized minerals may be separated from the demineralized tissue residue, i.e., the solubilized minerals may be poured out of a vessel containing the solubilized minerals and the demineralized tissue residue. The solubilized minerals may be collected and advantageously utilized in further processes or products, or they may be disposed of.

[0071] In the fifth process, the demineralized tissue residue undergoes a further enzymatic hydrolysis process, where hydrolysis may have an enhanced effect compared to mineralized tissue due to the lack of inorganic matter acting as a barrier to the reaction between proteins and enzymes, thus increasing the yield of proteins / polypeptides / amino acids from organic feedstock.

[0072] The second precipitate fraction of the product of the second hydrolysis process, i.e., the insoluble protein, can be sent to a dryer for collection. This dryer can also receive the product of the first continuous flow process, so the second precipitate fraction can be combined with the first precipitate fraction (produced by the first hydrolysis process) in the dryer for collection. This collection of the precipitate fraction ensures that no product loss from the insoluble protein occurs.

[0073] The aqueous fraction of the product of the second hydrolysis reaction is sent for further processing. Further processing may include evaporating the volatile components of the aqueous fraction, e.g., water, leaving behind any proteins / polypeptides / amino acids that were present in the aqueous fraction. The evaporated portion is poured off for collection or disposal, and the remaining components are collected as a peptide paste or spray dried to form a peptide powder. The peptide paste may be a collagen-peptide paste (i.e., a paste containing peptides derived from the hydrolysis of collagen) and the peptide powder may be a collagen-peptide powder (i.e., a powder containing peptides derived from the hydrolysis of collagen).

[0074] Although Processes 1 through 5 are described above, it should be appreciated that the methods of treating the material produced in the hydrolysis and demineralization processes are not limited to use in the specific Processes 1 through 5 described above, but may be combined in any combination to achieve a desired end product.

[0075] The method of the second embodiment includes performing enzymatic hydrolysis of an organic feedstock to produce a hydrolyzed fraction and a mineralized tissue residue, separating the mineralized tissue residue from the hydrolyzed fraction, and demineralizing the mineralized tissue residue to produce solubilized minerals and a demineralized tissue residue.

[0076] Any of the following process steps may then be combined in any combination with the aforementioned method of the second aspect to achieve the desired end product.

[0077] The hydrolyzate fraction may be separated into an aqueous fraction containing water with dissolved proteins, polypeptides, and amino acids, a sediment fraction containing insoluble proteins and other small solids, and an oil fraction.

[0078] The aqueous fraction (or a portion thereof) may be at least partially dried.

[0079] The precipitate fraction (or a portion thereof) may be at least partially dried.

[0080] The solubilized minerals can be separated from the demineralized tissue residue.

[0081] The solubilized minerals may be recovered by neutralizing the solution of the solubilized minerals, optionally using NaOH or KOH. The neutralized solution may be centrifuged or filtered such that the minerals are collected to form a mineral slurry. The mineral slurry may be at least partially dried to form mineral solids.

[0082] The calcified tissue residue (or a portion thereof) may be at least partially dried.

[0083] The demineralized tissue residue (or a portion thereof) may be at least partially dried.

[0084] The mineralized tissue residue (or a portion thereof) and the demineralized tissue residue (or a portion thereof) may be (at least partially) dried together.

[0085] A second enzymatic hydrolysis process may be performed on at least a portion of the demineralized tissue residue. The second enzymatic hydrolysis process may include the use of a protease. The resulting aqueous fraction (containing water with dissolved proteins, polypeptides, and amino acids) and the sediment fraction (containing insoluble proteins and other small solids) may each be (at least partially) dried.

[0086] At least a portion of the demineralized tissue residue may be recycled back into the organic feedstock for enzymatic hydrolysis.

[0087] In any of the foregoing processes, optionally, demineralizing the calcified tissue residue is carried out in a rotating drum reactor including a drum, an inlet at a first point on the drum, a screw within the drum, the screw including a helical blade extending along the length of the drum, an outer edge of the helical blade being fixed to an inner surface of the drum such that material may be transported and mixed by the helical blade as the drum rotates, and an outlet at a second point along the drum. Optionally, the drum is positioned such that the length of the drum and the axis of rotation of the drum extend generally along a horizontal.

[0088] Optionally, the enzymatic hydrolysis of the organic feedstock is carried out in a rotating drum reactor comprising a drum, an inlet at a first point on the drum, a screw within the drum, the screw including a helical blade extending along the length of the drum, an outer edge of the helical blade being fixed to an inner surface of the drum such that the material may be transported and mixed by the helical blade as the drum rotates, and an outlet at a second point along the drum. Optionally, the drum is positioned such that the length of the drum and the axis of rotation of the drum extend generally along a horizontal.

[0089] Optionally, enzymatic hydrolysis of the organic feedstock occurs in a first rotating drum reactor and demineralization of the mineralized tissue residue occurs in a second rotating drum reactor.

[0090] The rotating drum serves to mix the reactants of the enzymatic hydrolysis or demineralization process, while the turns of the screw serve to advance the material from the inlet to the outlet. The blades of the screw transport the material longitudinally along the drum. This may result in more efficient mixing and processing of the material than prior art devices that do not incorporate rotation or screw blades.

[0091] The residence time of the reactants within the rotating drum can be influenced by the number of turns of the screw blades (given by the length (in meters) of the rotating drum reactor vessel divided by the pitch (in meters)) and the rotation speed.

[0092] The ratio of pitch to drum length may be, for example, approximately 1:20, approximately 1:30, or approximately 1:40.

[0093] Further structural features of the rotating drum reactor are described below as optional features in relation to the fourth aspect of the invention, and such features are also applicable to the rotating drum used in the present method (to perform the enzymatic hydrolysis of the organic feedstock and / or the demineralization of the mineralized tissue residues).

[0094] Optionally, the method further comprises comminuting the organic feedstock prior to carrying out the enzymatic hydrolysis.

[0095] Therefore, the organic feedstock material can be mechanically comminuted and separated into size-reduced pieces prior to the enzymatic hydrolysis process. This increases the surface area of ​​the organic feedstock material, which can then be contacted with the enzymatic hydrolysis reagent. The greater contact area between the reactants can increase the reaction rate. In addition to the larger surface area, smaller pieces of organic feedstock require the hydrolysis reagent to penetrate a shorter distance to react with the material at the center of each piece. Thus, hydrolysis is accomplished more quickly and efficiently than with larger pieces. In addition, by reducing the size of the organic feedstock material, high shear forces within the reagent during hydrolysis can be avoided. Shear forces can be caused by too high fluid velocities and contribute to the generation of undesirable emulsions.

[0096] Optionally, the separation of the mineralized tissue residue from the hydrolysis fraction can be performed using a sieve or using a dewatering screw, drum sieve, filter, diverter, or device for separating components via sedimentation. If a sieve is used, the sieve can optionally be a vibrating sieve. The sieve can have a pore size of, for example, 2-6 mm. Multiple sieves can be used to separate multiple groups of particle sizes.

[0097] According to a third aspect of the present invention there is provided a processing plant for processing an organic feedstock comprising mineralized tissue material, as claimed in claim 21. The processing plant comprises a first reaction vessel configured to perform enzymatic hydrolysis of the organic feedstock, a first separator configured to receive an output from the first reaction vessel for separating the mineralized tissue residue discharged from the first reaction vessel from a hydrolysis fraction discharged from the first reaction vessel, and a second reaction vessel configured to perform demineralization of the mineralized tissue residue.

[0098] Optionally, the calcified tissue residue comprises a protein moiety.

[0099] Optionally, the processing plant is configured to carry out the method of the first or second aspect, and optionally includes any of the optional method features described above.

[0100] The processing plant is optionally configured to carry out the processing of the organic feedstock as a continuous process.

[0101] The processing plant may include an inactivation section downstream of the first reaction vessel to heat the material discharged from the first reaction vessel to a temperature sufficient to inactivate the enzyme (i.e., the enzyme is deactivated or denatured). The material may, for example, pass through a pipe surrounded by a heat exchanger to heat the pipe and contents. In one non-limiting example, the material may be heated to about 95° C. for about 10 minutes. The temperature to which the material is heated (and the time it is held at that temperature) may be appropriately selected depending on the enzyme used.

[0102] Organic feedstocks may, for example, be derived from or include fish off-cuts (e.g., salmon or cod), or chicken off-cuts, or meat off-cuts, including other animal origins. In particular, organic feedstocks may be derived from waste products generated by the food industry, or may be a secondary product of another industrial process. Organic feedstocks may include "industrial fish", i.e. raw materials used to produce fishmeal. Processing may therefore help to utilise discarded products and minimise waste.

[0103] Depending on the organic feedstock, the mineralized tissue present in the organic feedstock may include one or more of bone, fish scales, tendons, cartilage, tooth enamel, dentin, and hoof. Preferably, the mineralized tissue includes bone. The organic feedstock may include meat and bone from an aquatic animal source (e.g., from a marine animal) or a terrestrial animal source.

[0104] Mineralized tissue within the organic feedstock may comprise a protein portion (i.e., a portion consisting of protein) and a mineral portion. The mineral portion and the protein portion together may comprise the majority of the mineralized tissue residue. If the mineralized tissue is bone, the mineral portion of the mineralized tissue may comprise calcium hydroxyapatite. If the mineralized tissue is bone, the protein portion may comprise ossein (which comprises primarily collagen).

[0105] Optionally, the demineralized tissue residue comprises a protein portion, e.g., a majority of the demineralized tissue residue comprises protein.

[0106] Optionally, the processing plant comprises a sieve, a dewatering screw press, a filter, or a density separator for separating the calcified tissue residue from the hydrolysis fraction.

[0107] Optionally, the treatment plant comprises a three-phase separator for separating the hydrolyzed fraction into an aqueous fraction comprising water with dissolved proteins, polypeptides and amino acids, a sediment fraction comprising insoluble proteins, and an oil fraction.

[0108] Optionally, the processing plant comprises a separator for separating the solubilized minerals from the demineralized tissue residues.

[0109] Optionally, the processing plant comprises a third reaction vessel for carrying out a second enzymatic hydrolysis process on a portion of the demineralized tissue residue. The processing plant is thus configured to carry out enzymatic hydrolysis of the demineralized tissue residue discharged from the second reaction vessel. The enzymatic hydrolysis of the demineralized tissue residue results in at least a portion of the protein portion of the demineralized tissue residue being hydrolyzed. The mineralized tissue residue comprises protein portions that are possible, but not readily achievable, to be processed via further enzymatic hydrolysis, in which the protein is broken down into its hydrolysis components. The demineralized tissue residue may comprise protein portions that are readily achievable to be processed via further enzymatic hydrolysis, in which the protein is broken down into its hydrolysis components. Optionally, the second enzymatic hydrolysis process comprises the use of a protease.

[0110] In this example, separate vessels are used to carry out the enzymatic hydrolysis of the organic feedstock and the enzymatic hydrolysis of the demineralized tissue residue. The reaction parameters, such as temperature, duration, choice of enzyme used (e.g., protease), concentration of reagents in the enzymatic hydrolysis solution, and ratio of hydrolysis solution to solids, can be different in each reaction vessel and therefore adjusted to the requirements of the reaction materials.

[0111] The processing plant may include an inactivation section downstream of the third reactor to heat the material discharged from the third reactor to a temperature sufficient to inactivate the enzyme (i.e., the enzyme is deactivated or denatured). The material may, for example, pass through a pipe surrounded by a heat exchanger to heat the pipe and contents. In one non-limiting example, the material may be heated to about 95° C. The temperature to which the material is heated may be appropriately selected depending on the enzyme used.

[0112] Optionally, the treatment plant comprises a separator for separating the effluent of the third reaction vessel into a sediment fraction and an aqueous fraction.

[0113] Optionally, the first reaction vessel is configured to receive a portion of the demineralized tissue residue expelled from the second reaction vessel.

[0114] Optionally, the processing plant comprises one or more dryers, where the one or more dryers include a mill dryer, and / or an evaporator, and / or a spray dryer.

[0115] An evaporator may be used to partially dry the aqueous fraction (to form a paste). A dryer may be used to completely dry the aqueous fraction (to form a meal). In general, it is not energy intensive (and therefore low cost) to first partially dry the aqueous fraction (to form a paste) using an evaporator and then transfer the paste to a dryer to completely dry the paste. Thus, drying the aqueous fraction may be a two-step process that includes first partially drying the aqueous fraction (in an evaporator) to form a paste and then completely drying the paste (in a dryer) to form a meal.

[0116] A spray dryer may be used to form a powder from the paste. The paste received by the spray dryer should typically contain 30-50% dry matter, somewhat depending on particle size and viscosity. If the spray dryer is not co-located with the evaporator, the evaporator should produce a paste with more than 60% dry matter (for the paste to be microbiologically stable), and then water must be added back to the paste before injection into the spray dryer.

[0117] Correspondingly, the precipitate fraction may also be partially or completely dried. Since the precipitate fraction has physical properties that make it difficult to process in a conventional evaporator, a dryer may be used to partially or completely dry the precipitate fraction.

[0118] Optionally, the treatment plant comprises a flow splitter configured to split the flow of mineralized or demineralized tissue residue into a plurality of flows. The flow splitter may be provided by a combination of a screw conveyor and a rotary dosing valve. The mineralized tissue residue may move along a screw conveyor (with the screw conveyor positioned substantially horizontally or at a small angle to the horizontal) under which the rotary dosing valve is mounted. A part of the mineralized tissue residue may be diverted from the main flow by the rotary dosing valve, while the remainder of the mineralized tissue residue is transported further by the conveyor. The flow splitter thus splits the flow of mineralized tissue residue into two parts in a non-selective manner. The relative sizes of the two split flows may be set by the rotational speed of the rotary dosing valve.

[0119] Optionally, at least one of the first, second, and third reaction vessels is a rotating drum reactor, the rotating drum reactor including: a drum, rotatable about a central longitudinal axis of the drum; an inlet at a first point on the drum; a screw in the drum, the screw including a helical blade extending along the length of the drum, an outer edge of the helical blade being fixed to an inner surface of the drum such that materials may be transported and mixed by the helical blade as the drum rotates; and an outlet at a second point along the drum. Optionally, the central longitudinal axis of the drum is substantially horizontal.

[0120] The above-mentioned optional features of the processing plant can be combined in any combination to arrive at a processing plant suitable for producing a desired end product. The following discussion shows five examples of processing plants used to target different end products.

[0121] Optionally, in the first processing plant, the processing plant further comprises a diverter and a dryer, the diverter configured to divert a first portion of the calcified tissue residue discharged from the first reaction vessel to the dryer and to divert a second portion of the calcified tissue residue discharged from the first reaction vessel to the second reaction vessel.

[0122] The dryer may be a mill dryer that simultaneously grinds and dries the calcified tissue residue.

[0123] Any desired proportion of the mineralized tissue residue may be diverted to the dryer depending on process relevant factors such as the raw materials used, the products desired to be collected, and process economics. The appropriate percentage sent to the dryer may be selected accordingly.

[0124] The second portion of the calcified tissue remnant may include a portion of the calcified tissue remnant remaining after the first portion has been removed.

[0125] Optionally, the dryer is also configured to receive demineralized tissue residue discharged from the second reaction vessel.

[0126] The dryer removes remaining water or other liquids from the first portion of the calcified tissue residue discharged from the first reaction vessel, and, if appropriate, removes remaining water or other liquids from the decalcified tissue residue discharged from the second reaction vessel.

[0127] Optionally, a second dryer may receive the demineralized tissue residue discharged from the second reaction vessel.

[0128] Optionally, in the second processing plant, the processing plant further comprises a third reaction vessel configured to perform enzymatic hydrolysis of the demineralized tissue residue discharged from the second reaction vessel.

[0129] In this example, separate vessels are used to perform the enzymatic hydrolysis of the organic feedstock and the enzymatic hydrolysis of the demineralized tissue residue. The layout of the processing plant can be more flexible in this configuration, since there are fewer constraints on how the vessels must be positioned to form such a loop than if each of the enzymatic hydrolysis processes were carried out in the same reaction vessel.

[0130] Optionally, in the third processing plant, the first reaction vessel is configured to receive demineralized tissue residue discharged from the second reaction vessel.

[0131] Thus, the demineralized tissue residue discharged from the second reaction vessel is recycled to the first reaction vessel. The demineralized tissue residue can be combined with the raw starting material, i.e., organic feedstock, to enter the first reaction vessel at the inlet of the first reaction vessel. This processing plant requires less space to operate, since only two reaction vessels are required, compared to a processing plant in which the hydrolysis of the demineralized tissue takes place in a third reaction vessel. Compared to such a processing plant, other resources, including reactant resources and the energy required for the reaction, can also be saved.

[0132] Optionally, in the fourth processing plant, the processing plant further comprises a dryer configured to dry the demineralized tissue residue discharged from the second reaction vessel.

[0133] The dryer can form a protein paste from the demineralized tissue residue discharged by the second reaction vessel. The protein paste can be a collagen paste. Thus, the demineralized tissue residue does not have to undergo a second enzymatic hydrolysis reaction before it is collected and used to form the product.

[0134] Optionally, in the fifth processing plant, the processing plant further comprises a third reaction vessel configured to perform enzymatic hydrolysis (e.g., using a protease) of the demineralized tissue residue discharged from the second reaction vessel, a second separator configured to receive the output of the third reaction vessel for separating a sediment fraction of the output of the third reaction vessel from an aqueous fraction of the output of the third reaction vessel, an evaporator configured to dry the aqueous fraction of the output of the third reaction vessel to form a peptide paste, and a spray dryer configured to form a peptide powder from the peptide paste. The paste received by the spray dryer should typically contain 30-50% dry matter, somewhat depending on particle size and viscosity. If the spray dryer is not co-located with the evaporator, the evaporator should produce a paste with more than 60% dry matter (for the paste to be microbiologically stable), then water should be added back to the paste before injection into the spray dryer.

[0135] Thus, the demineralized tissue residue undergoes further enzymatic hydrolysis processes and hydrolysis of the demineralized tissue residue may be more complete than the mineralized tissue of the organic feedstock since minerals that may inhibit the hydrolysis reaction have now been removed.

[0136] The precipitate fraction from the third reaction vessel, i.e., the insoluble proteins remaining after enzymatic hydrolysis of the decalcified tissue residue, may be sent to a dryer for collection. This dryer may also receive the product from the first reaction vessel, so the solid fraction from the third reaction vessel may be recombined with the precipitate fraction from the first hydrolysis process in the dryer for collection. This collection of the precipitate fraction ensures that no product loss from the insoluble proteins occurs. The aqueous fraction of the product of the second hydrolysis reaction is sent for further processing. Further processing may include evaporating the volatile components of the aqueous fraction, e.g., water, leaving behind any proteins / polypeptides / amino acids that were present in the aqueous fraction. The evaporated portion is poured off for collection or disposal, and the remaining components are collected as a peptide paste or spray dried to form a peptide powder, or the peptide paste may be sent to a dryer to form a peptide meal. The peptide paste may be a collagen-peptide paste (i.e., a paste containing peptides derived from the hydrolysis of collagen), and the peptide powder may be a collagen-peptide powder (i.e., a powder containing peptides derived from the hydrolysis of collagen).

[0137] Optionally, at least one of the first, second, and third reaction vessels is a rotating drum reactor including a drum, an inlet at a first point on the drum, a screw within the drum, the screw including a helical blade extending along the length of the drum, an outer edge of the helical blade being fixed to an inner surface of the drum such that materials may be transported and mixed by the helical blade as the drum rotates, and an outlet at a second point along the drum.

[0138] The drum is optionally positioned such that the length of the drum and the axis of rotation of the drum extend substantially horizontally.

[0139] Optionally, each of the first, second, and third reaction vessels is a rotating drum reactor.

[0140] The rotating drum serves to mix the reactants of the enzymatic hydrolysis or demineralization process, while the screw turns serve to advance the material along the turns of the screw from the inlet to the outlet. The screw blades transport the material longitudinally along the drum. This may result in more effective mixing and processing of the material than prior art devices that do not incorporate rotation or screw blades.

[0141] Further structural features of the rotating drum reactor are described below as optional features in relation to the fourth aspect of the invention, and such features may be combined with the rotating drum reactor when optionally used as at least one of the first, second and third reaction vessels in the above described first, second or third aspects of the invention.

[0142] The processing plant according to the third aspect may be configured to carry out the method of processing organic feedstock comprising mineralised tissue according to the first and / or second aspects.

[0143] The concept of using a rotating drum reactor for demineralizing calcified tissue is considered to be independently patentable.

[0144] Thus, according to a fourth aspect of the present invention there is provided a method of demineralising calcified tissue, as set out in claim 33. The method comprises treating calcified tissue with an acid solution in a rotating drum reactor comprising a drum, a drum inlet at a first point on the drum, a screw within the drum and a drum outlet at a second point along the drum, the screw comprising a helical blade extending along the length of the drum, an outer edge of the helical blade being fixed to an inner surface of the drum such that material within the drum is mixed and transported through the drum by the helical blade as the drum rotates.

[0145] The drum is optionally positioned such that the length of the drum and the axis of rotation of the drum extend substantially horizontally.

[0146] The drum of a rotating drum reactor may extend approximately horizontally such that the level of fluid within the drum remains substantially the same distance from the bottom of the drum at all points along the length of the drum.

[0147] The outlet of the drum may be downstream of the inlet such that reactants introduced into the drum at the inlet flow along the axial extent of the drum from the inlet to the outlet. Thus, the inlet may be horizontally offset from the outlet. The inlet may be at one end or substantially at one end of the drum and the outlet may be at the opposite end or substantially at the opposite end of the drum. The drum may be cylindrical with substantially the same axial cross section throughout its length. The axial cross section of the drum may be circular.

[0148] The radially outer edge of the helical blade may be fixed to the inner surface of the drum, so that the helical blade follows the inner circumference of the drum as the helix travels from an inlet at one end of the drum to an outlet at the opposite end of the drum. The blade directs and pushes the solid material at the bottom of the drum, as well as the fluid within the drum, toward the outlet of the drum. As the drum rotates, the reactants are mixed, helping to maintain a high reaction rate. To enable the device to be used with fluid raw materials, the helical blade is preferably attached at its outer edge to the inner surface of the drum in a watertight joint.

[0149] In this arrangement, the screw blades form a series of chambers between adjacent turns of the helical blade, where a "turn" of the helical blade describes a rotation of 360°. In other words, the pitch of the screw blade is the distance between any two points on the helix that are exactly one turn apart.

[0150] In some operating modes of a rotating drum reactor, separate batches of material may be processed in each chamber without direct contact with adjacent batches of material in adjacent chambers. Advantageously, this allows different reaction mixtures to be used in different chambers, for example, by introducing additional reactants as the material is transported along the length of the drum.

[0151] Optionally, the method is carried out as a continuous flow process. Thus, the method is preferably not a batch process in which the demineralization process is carried out in blocks with process downtime between each batch as reaction products are removed and fresh reactants are added, but instead the demineralization process is carried out such that fresh reactants are added continuously or substantially continuously at the inlet as products are continuously or substantially continuously removed from the reactor drum via the outlet. Reference to a continuous flow process herein is intended to encompass a process in which the flow through the rotating drum occurs in a single pass, without repeated rounds or batch-wise processing. Depending on the nature of the reaction, additional materials may be added continuously during the process.

[0152] Optionally, the helical blade extends from the inner surface of the drum toward the center of the drum, but does not extend along the entire diameter of the drum, such that the open flow path extends along the axial length of the drum. This may allow access during manufacturing as well as for maintenance, and also allows for easier cleaning of the device since there are fewer fully enclosed chambers. Such a configuration also allows operation of the rotating drum reactor in a "flooded mode," discussed in more detail below. In such a mode, the open flow path may allow fluid to pass between chambers where there is enough fluid to overflow the chamber barriers formed by the blades. The screw blade may extend inward from the wall of the drum over at least 50% of the radius of the drum, for example at least 60% or about 70% of the radius of the drum.

[0153] Optionally, the acid solution fills the rotating drum reactor above the level of the helical blades, which is referred to as a "flooded mode" of operation of the rotating drum reactor.

[0154] The solid portion of the organic feedstock (including mineralized tissues such as bones, and other animal parts such as fish scales, hooves, etc.) sinks to the base of the drum so that the solid portions remain in their separated volume between the walls of the blades. However, in a submerged mode of operation, the acid in the chambers of the drum overflows into the subsequent chambers in the direction of the outlet, causing an increase in the flow of the acid solution in the direction of the outlet of the drum. Thus, when operated in a submerged mode, the drum allows fresh acid to be delivered to the chambers of the drum towards the outlet. The flow of the acid solution helps to replenish the consumed acid in the chambers towards the outlet of the drum, thus maintaining the demineralization reaction rate along the length of the drum.

[0155] The density of the mineralized tissue ensures that it remains at the base of the chamber, rather than flowing through the open channels via flow caused by the overflow of the acid solution. Thus, the residence time of the mineralized tissue is not affected by the use of the submerged mode, but instead remains controlled by the rotation of the drum.

[0156] By modifying the process to replenish reactive acid along the length of the drum, demineralization can be completed in less time and over a correspondingly shorter length of drum, allowing the drum to be made smaller.

[0157] Optionally, the ratio of acid solution to calcified tissue residue increases along the length of the drum from the drum inlet to the drum outlet.

[0158] The gradual increase in acid allows the demineralization rate to be controlled; for example, acid consumed through the demineralization process occurring in the chamber toward the inlet of the drum can be replenished as reactants are conveyed toward the outlet of the drum to provide a more constant volume of reactive acid along the length of the drum, and thus approach a more constant demineralization rate throughout the process. Addition can be empirically optimized for a given feedstock and equipment configuration. By modifying the process to increase the ratio of acid solution along the length of the drum, thereby increasing the reaction rate versus keeping the ratio constant, demineralization can be completed in a shorter time and over a correspondingly shorter length of drum. As a result, the drum can be made smaller.

[0159] The screw blades are helical screw blades and therefore spiral along the inside of the rotating drum. The screw blades may have a constant pitch along the length of the drum or there may be a change in the pitch of the screw blade between the inlet and outlet.

[0160] Optionally, the pitch of the helical blade increases along the length of the drum, from the drum inlet towards the drum outlet. Thus, each chamber increases in volume towards the outlet of the drum. This is particularly advantageous when using a drum operating in a submerged mode, or when fluid is added to the material in the drum as it passes along the drum (discussed in more detail below), where the increased volume of the chambers can be advantageously used to accommodate the increased volume of material. Since the mineralized tissue remains at the base of the drum and is separated by the walls of the blade, the volume of tissue in each chamber remains constant as the tissue progresses through the drum. However, given that in a submerged mode, all chambers are filled to the same level that the acid solution may overflow the walls of the blade, the volume of acid solution in each chamber increases along the length of the drum as the pitch of the helical blade increases in response to the increase in the volume of the chamber. Thus, the ratio of acid solution to mineralized tissue increases along the length of the drum. This has the advantage of increasing the presence of reactive acid compared to consumed acid, thus helping to maintain the desired reaction rate.

[0161] As discussed above, in some embodiments, the helical blade extends from the inner surface of the drum towards the center of the drum, but does not extend along the entire diameter of the drum, such that an open flow path extends along the axial length of the drum. The chambers formed between adjacent turns of the screw blade are then open to the hole in the center of the drum. Alternatively, however, these chambers may be closed, for example, by a cylinder along the center of the drum, which is preferably fixed to the inner edge of the screw blade in a watertight manner. In this case, there are no open flow paths extending along the axial length of the drum. In this arrangement, the screw blade forms a series of closed chambers in which separate batches of material may be processed without direct contact with adjacent batches of material. Advantageously, this allows different reaction mixtures to be used in different chambers, for example, by introducing additional reactants as the material is conveyed along the length of the drum. Such a configuration with closed chambers may allow a larger volume of material to be held without the risk of spillage between adjacent turns of the screw blade, as well as allowing for smaller headspaces and potentially better control of the atmosphere within the headspace. Additionally, allowing for a higher degree of packing may allow the size of the drum to be reduced.

[0162] Optionally, the rotating drum reactor includes multiple fluid inlets opening into the drum along the axial length of the drum.

[0163] The fluid inlet may be arranged to supply fluid under pressure such that the fluid is sprayed from the fluid inlet onto the material in the drum, which may aid in mixing of the material.

[0164] The use of fluid inlets may allow the ratio of materials to be adjusted, for example, by adding diluents or additional reagents to the materials in the rotating drum. Preferably, there are a sufficient number and suitable spacing of fluid inlets to allow one or more fluid inlets for each turn of the screw. In this case, during each turn of the screw, fluid is added to the original raw materials, thereby increasing the amount of fluid added compared to the amount of original raw materials as the mixed materials pass longitudinally along the drum.

[0165] The fluid inlets may include groups of fluid inlets at spaced locations along the screw blade.

[0166] It is advantageous for the device to be arranged so that the supply of fluid to the drum via the fluid inlets can be controlled. The device may therefore include a fluid flow control device for controlling the flow rate of fluid through the fluid inlets, in particular for allowing or preventing flow. For example, the device may include a valve for controlling the flow to each fluid inlet or to a group of fluid inlets. In this case, a controller is preferably provided that is arranged to allow flow through the fluid inlets immersed in the material to be mixed and to prevent flow when the fluid inlets are not in the material to be mixed. Thus, flow is allowed when the fluid inlets are at their low points in the rotation of the drum and within the level of the material being mixed in the drum, but flow is not allowed when the fluid inlets are at their higher points during the rotation of the drum and above the level of the material being mixed. In one example, the controller is in conjunction with a sensor that allows the rotation of the drum to be monitored, so that the fluid inlets are only allowed to supply fluid when they are in a position where they are expected to be immersed in the material to be mixed. Alternatively or additionally, the controller may include a switching device located adjacent to the expected level of material in the drum so that individual fluid inlets are activated and deactivated as they pass through the switching device to enter and exit the material at the base of the drum.

[0167] The method may include introducing a fluid to the material, for example introducing a liquid or gas as described above. The method may include heating or cooling the material in the drum by introducing a fluid at a high or low temperature. Heating or cooling the material may be done to inactivate / denaturate the enzymes, stopping the enzymatic reaction.

[0168] The method may include controlling the supply of fluid through the fluid inlets such that fluid is supplied only when the fluid inlets are submerged in the material in the drum. This may be done using features as discussed above, for example by controlling the flow of fluid according to the position of each fluid inlet in the drum.

[0169] Each of the fluid inlets may be connected to a pipe for supplying fluid from a fluid source to the fluid inlets. This pipe may advantageously be installed towards the center of the drum, thereby minimizing the risk of the pipe coming into contact with the material being mixed in the drum. This may cause corrosion or fouling of the pipe or the mixture in the drum. Alternatively, the pipe may be outside the drum and may be connected to the mixing device, optionally by passing through the body of the screw blade, thereby avoiding any contact with the material in the drum. The connection allowing the passage of fluid from the fluid source into the drum is preferably installed in the center of the rotating drum, for example at one or both ends of the drum. Thus, the drum may include a rotary valve installed along the axis of rotation of the drum, the rotary valve being configured to allow fluid to enter the pipe in the drum during rotation of the drum. Optionally, two rotary valves may be provided at one of the two ends of the drum, respectively.

[0170] Optionally, acid solution is introduced into the drum through multiple fluid inlets. Thus, fresh acid capable of reacting with mineralized tissue minerals is introduced into the drum at various points other than the inlet. The amount of additional acid solution added to the drum may increase toward the outlet of the drum to ensure that there is a sufficient volume of reactive acid to continue the demineralization process at a desired rate. The reaction rate may remain substantially constant.

[0171] As discussed above, the pitch of the helical blades may increase along the length of the drum from the drum inlet towards the drum outlet, which is particularly advantageous when additional acid is introduced into the drum through multiple fluid inlets towards the drum outlet.

[0172] The rotating drum may include multiple mixing devices to promote mixing of the materials in each of the volumes of material as the materials are conveyed along the screw, and the multiple mixing devices may be spaced along the blades of the screw, with at least one mixing device for each turn of the screw blade.

[0173] In this arrangement, the material to be mixed and processed travels from the inlet to the outlet along the turns of the screw, undergoing mixing due to the rotation of the drum, the "push" of the screw blades to transport the material longitudinally along the drum, and also due to the addition of mixing devices spaced along the screw blades. This can result in more effective mixing and processing of the material than prior art devices that do not include additional mixing devices at each turn of the screw. By locating the mixing devices spaced along the screw and having at least one mixing device for each turn of the screw, a mixing device acts on each volume of material as it is transported along the screw.

[0174] It is preferred that there are multiple mixing devices for each turn of the screw, and there may be, for example, a sufficient number of mixing devices so that at least one of them is always in contact with the material as it is conveyed along the screw. It will be understood that in this type of rotating screw device, the material to be mixed and conveyed is located at the base of the device in a chamber formed between the turns of the screw, and there is a head space above the level of the material. To obtain the best effect from the mixing device, it is advantageous that there is always a mixing device that is below the level of the material and in contact with the material, so that there is never a period of time when the material is not subjected to the action of the mixing device. For example, if the level of material in a drum during normal use can be approximated as a segment of a circle (assuming a cylindrical drum) formed by a chord that arcs 90°, then if there are four equally spaced mixing devices on each turn of the blades of the screw, then there is always a mixing device in contact with the material. There may be four or more, optionally five or more, or six or more mixing devices for each turn of the blades of the screw. A greater number of mixing devices may be included if the level of material in the drum is expected to be low enough during normal use to require smaller spacing between the devices, or if it is deemed advantageous to have more than one mixing device in contact with the material at all times.

[0175] The mixing device may include mixing flights spaced along the screw having multiple flights for each turn of the screw, the flights being positioned to promote mixing of the materials being processed.

[0176] Each of the multiple mixing devices may include a mixing flight, or alternatively there may be multiple types of mixing devices where only some of the multiple mixing devices include a mixing flight. The mixing flight preferably takes the form of an element attached to the blade of the screw having a surface with a larger angle of attack than the surface of the blade of the screw. Thus, the mixing flight may include an inclined surface with a larger angle of attack than the surface of the screw blade.

[0177] Each mixing flight may include identical inclined surfaces with the same angle of attack, or alternatively, the angle of the inclined surfaces of the mixing flights may vary, e.g., with increasing or decreasing angles of attack of the mixing flights depending on the location of the mixing flights along the extent of the blades of the screw.

[0178] In one example, the inclined surface of the mixing flight is the upper surface of a wedge-shaped element, and the lower surface of the wedge-shaped element is adjacent to and attached to or integrally formed with the surface of the screw blade, for example, it can be attached by welding or it can be formed with the screw blade in a casting process. The mixing flight can be considered to have a front edge at the beginning of the inclined surface where the mixing flight first enters the material held in the volume between the two turns of the screw in use, and a rear edge at the end of the inclined surface farthest from the surface of the screw blade, the rear edge being the edge that lastly encounters the material held in the screw. When a wedge-shaped element is used, the rear edge is the apex of the wedge-shaped element at the point farthest from the surface of the screw blade.

[0179] It is advantageous for the mixing flight to be attached to the outer part of the surface of the screw blade, i.e. adjacent to the inner wall of the drum. This means that the mixing flight affects the mixing of all the materials in the volume between the two turns of the screw, including the deepest extent of these materials. The mixing flight may extend from the inner wall of the drum along the surface of the screw blade towards the center of rotation of the drum. The mixing flight may extend to the same extent as the screw blade towards the center of rotation, or to a lesser extent. Except when used in submerged mode, the screw blade typically extends far enough towards the center of the drum so as to be above the level of the material held in each volume between the turns of the screw. This avoids intermixing of materials from adjacent turns. The mixing flight may extend towards the center of the drum to a smaller extent than the screw blade, for example to the extent necessary to ensure that the mixing flight is completely immersed in the material held in the volume between the two turns of the screw. The greatest influence of the mixing flight is typically the deepest part of the material in the volume between the two turns of the screw, since this is where the larger and heavier elements of the material collect.

[0180] The height of the mixing flight, i.e. the extent of the mixing flight from the wall of the drum towards the center of the drum, can be at least 30% of the expected level of material in the drum, for example 40% or more of this level. The screw blades typically do not have to extend completely across the width of the drum, so there can be holes along the center of the screw blade at the center of the rotating drum. The height of the mixing flight can be at least 20% of the height of the screw blade, for example at least 30% of the height of the screw blade. The mixing flight is preferably fully immersed when in the deepest part of the material held in the drum, and therefore the height of the mixing flight can be below the expected level of the liquid, such as 80% or less of the liquid height. At typical liquid levels in the device at this time, this may require a flight having a height of less than 70% of the height of the screw blade, optionally less than 60% of the height of the screw blade. Possible dimensions of the screw blade are discussed in more detail below.

[0181] The mixing device may include a fluid inlet (as described above) for adding fluid to the mixture in each volume between turns of the screw. Each of the multiple mixing devices may include a fluid inlet, or alternatively there may be multiple types of mixing devices, where only some of the multiple mixing devices include a fluid inlet. The fluid inlet may advantageously be combined with a mixing flight, optionally opening into the drum at a surface or edge of the mixing flight. In one example, each of the mixing devices includes a mixing flight having an inclined surface as described above, and also having one or more fluid inlets at the rear edge of the inclined surface, i.e. at the furthest point of the inclined surface from the screw blade.

[0182] The mixing device may alternatively or additionally include one or more of vanes, paddles, scoops, or ridges in the wall of the drum, moving parts (e.g., rotors) with passive or active movement attached to the drum or screw blades, and / or other static or dynamic mixing devices.

[0183] The inlets to and outlets from the rotating drum may be at the longitudinal ends of the drum. The inlets may include an opening at the inlet end of the drum through which an inlet pipe passes to allow material to be fed into the rotating drum reactor. In the case of a cylindrical drum, the inlet end of the drum may include a closed outer portion with an open inner portion, thus taking the form of a disk covering the end of a cylinder with a hole in the center of the disk. The central hole may receive the inlet pipe and may also receive tubing for feeding fluid to the fluid inlet.

[0184] The outlet may include an opening at the outlet end of the drum, for example, the outlet end of the drum may be fully open, allowing material within the drum to exit the drum as it passes through the final turn of the screw blades. The outlet may include a hopper or the like to receive the material exiting the drum and direct it to the next stage of processing.

[0185] Since the material in the drum is conveyed through the screw blade, the geometry of the helical screw blade means that if the blade simply terminates without any modification to the shape of the last turn of the screw blade, the material will not flow continuously from the drum, but instead the flow rate will fluctuate. This uneven flow may not be a problem in some circumstances, as there may be the possibility of using a hopper or the like as a buffer to collect the material and ensure that a continuous flow can be sent to the next stage of processing. However, in some cases it is necessary to provide a more uniform flow rate from the outlet of the drum.

[0186] To provide a more uniform flow rate from the outlet of the drum, the drum and / or the screw blades may be provided with an outlet feature during the final turn of the screw blades. The screw blades may be reduced in size toward the outlet end to allow the flow of material to spill over the blades and thus exit the drum more uniformly. However, for materials that are not homogenous and include, for example, liquid material as well as solid particles such as bone, this may result in the liquid material exiting the drum uniformly, while the solid particles that settle toward the lower portion of the drum and therefore do not spill over the blades still exit at a non-uniform rate.

[0187] An alternative approach is to include holes in the drum wall and / or the surface of the screw blade during the final turn of the screw blade to reduce flow rate fluctuations. Holes in the drum wall may require complex arrangements to capture the flow from the outlet, but may be beneficial for relatively non-viscous, homogenous materials. Holes in the drum wall can also be used to separate the liquid from smaller particles, with larger particles exiting the drum at the end of the drum. In this way, the rotating drum can be used as a separator.

[0188] In one example, the holes are provided with openings through the last turn of the screw blade to provide fluid communication between the volume formed between the last and penultimate turns of the blade and the outlet end of the rotating drum. The holes can be located at the outer periphery of the screw blade close to the wall of the drum and / or at spaced locations across the width of the screw blade. These holes can be located at spaced locations that encompass an area of ​​the screw blade similar to the area of ​​the mixing flight, for example. The use of holes in the screw blade can make the flow rate uniform, while also ensuring that there is a uniform flow for all parts of the material, even when, for example, there is a heterogeneous mixture of liquid and solid material. This is because the holes toward the outside of the screw blade, i.e., closest to the wall of the drum, in addition to allowing the passage of particles that have settled under gravity, also allow smaller particles and liquid to pass. If the rotating drum is intended to be used with materials containing solid particles, the hole size should be set based on the particle size to avoid undesired clogging of the holes.

[0189] The holes can be of adjustable size, for example using a sliding plate or an exchangeable plate, allowing adaptation of the rotating drum to different volumes of material, different sizes of solid particles, and different properties of the mixed material, such as solid / liquid ratio, viscosity, etc.

[0190] The total area of ​​the holes should preferably be sufficient to allow all of the material in the chamber formed between the last and penultimate turn of the screw to flow through the last turn of the screw blade toward the outlet end of the drum during one turn of the drum. This allows for a uniform flow rate of material out of the outlet of the drum. In a typical application, the total area of ​​the holes below the expected material level in the drum should be between 40 and 200 cm 2This can be achieved in the range of 180-850 cm of holes spaced around the circumference of the last turn of the screw blade, assuming that the last turn is open over 90° of the circumference of the drum, and thus the holes are spread over 270° of the circumference. 2 This total bore size may be in the context of a drum with a diameter ranging from 1 to 5 m and a total flow rate ranging from 1000 to 6000 liters per revolution of the drum, i.e. a volume of material retained between each pair of turns of the screw blades of 1000 to 6000 liters.

[0191] It should be appreciated that the length of the drum and the horizontal extent of the axis of rotation of the drum are features that allow the material in the drum to collect at the bottom of the drum under the action of gravity, thereby allowing the material to be mixed with the mixing device while the action of the screw blades transports the material along the length of the drum. The length of the drum and the axis of rotation of the drum do not need to be completely horizontal. Thus, the drum can also be set at an incline to transport the material in the drum vertically upwards or downwards. In this way, the rotating drum device can be used in a similar manner to an Archimedes screw, transporting and mixing the material vertically. If the inlet of the drum is higher than the outlet of the drum, the weight of the material in the drum can be used to help rotate the drum. This can advantageously allow the load on the motor or other drive for the rotation of the drum to be reduced.

[0192] The rotating drum device may include a drive device for driving the rotation of the drum, e.g., a motor attached to the drum via suitable gears. The rotating drum device may include a support for holding the drum and allowing the drum to rotate, e.g., a support incorporating bearings. The rotating drum may be held by roller bearings that support its outer surface, or alternatively, the rotating drum may be held via a shaft reported in journal bearings or the like.

[0193] The body of the rotating drum may advantageously be cylindrical, although it will be understood that other tubular shapes may be used. A circular outer periphery is generally simple to manufacture and may easily support rotation, for example by roller bearings supporting the outer surface of the drum itself. A circular drum also reduces turbulence within the drum itself during rotation, which may be advantageous for certain types of processes. Alternatively, a non-circular drum may be used, for example a hexagonal or octagonal prism. A non-circular drum may provide advantages in terms of mixing when a greater degree of turbulence is required.

[0194] In one example, the drum can be driven at 5m per hour. 3 For example, about 7m per hour 3 or more, or in other circumstances, approximately 30m per hour 3 The system is arranged to provide a processing capacity of 100 Mbps or more.

[0195] The diameter of the drum may be at least 2 m, for example 2.5 m to 3.5 m. The rotating drum may be arranged such that the time it takes for the raw materials to pass along the extent of the drum is at least 15 minutes, or at least 20 minutes, for example such time may be about 1 hour or more. This allows sufficient time for reactions to occur and / or for reagents to contact all of the raw materials.

[0196] The length of the drum between the inlet and the outlet may for example be 3m or more, such as 5.5m, or even more than 10m.

[0197] The pitch of the drum can be selected to provide a desired number of chambers within the drum and (in combination with the length of the drum and the rotational speed of the drum) a desired residence time of the material within the drum. The ratio of pitch to length of the drum can be, for example, approximately 1:20, approximately 1:30, or approximately 1:40.

[0198] The inlet and outlet may be at the ends of the drum. The diameter of the drum, the length of the drum, and the rotational speed of the drum may be set to provide the above throughput.

[0199] In one example, the length of the drum is 11.75m, the diameter of the drum is 3.5m, the screw blades extend 1.25m from the outer wall to the center of the drum, the pitch of the screw blades is 0.375m, and the mixing flights have a height of 0.5m. In this example, there may be five mixing flights for each turn of the screw blade and five fluid inlets spaced along the extent of the rear edge of the mixing flights. This drum can be operated at approximately 30m per hour in the form of 15 tonnes of raw material and 15 tonnes of water. 3 of material, with a travel time from inlet to outlet of approximately 1 hour.

[0200] Optionally, the acid solution used to demineralize the calcified tissue residue comprises hydrochloric acid. The acid solution may alternatively or additionally comprise other strong acids, such as sulfuric acid (H2SO4), nitric acid (HNO3), and phosphoric acid (H3PO4). The stronger the acid, the more effective it is at demineralizing the calcified tissue residue. Hydrochloric acid (HCl) has a favorable dissociation constant and has been found to be more economically viable than other acids. The use of HCl is also more practically viable, with lower health and safety risks and associated costs of using strong acids.

[0201] Optionally, the acid solution includes an acid at a concentration of 1-5% by weight. Optionally, the acid concentration is 1-4% by weight, or 2-3% by weight. Preferably, the acid concentration is approximately 3% by weight.

[0202] The concentration of the acid may depend on the composition of the mineralized tissue residue and therefore on the type of organic feedstock used. The concentration of the acid may also depend on the type of acid used. The concentration of the acid should be high enough so that the rate of the demineralization reaction is not unduly inhibited by the lack of acidic reactant, but not so high that unreacted acid is wasted. Both of these factors increase the economic efficiency of the demineralization process.

[0203] Optionally, the weight ratio of calcified tissue residue to acid solution is between 1:2 and 1:8.

[0204] Optionally, the weight ratio of the calcified tissue residue to the acid solution is 1:3 to 1:5. Optionally, the weight ratio of the calcified tissue residue to the acid solution is 1:5. Thus, the weight of the acid solution is large compared to the weight of the calcified tissue residue. This ensures that the acid solution encompasses all of the calcified tissue residue during decalcification, so that the rate of reaction is not limited by lack of contact between the acid and the calcified tissue residue. The weight percentage of the acid solution is limited to limit the amount of acid solution that is wasted for spatial and economic efficiency. The lower the percentage of acid solution used, the more calcified tissue residue can be processed in the same volume of container.

[0205] Optionally, decalcification of the calcified tissue residue is performed for 30 to 180 minutes.

[0206] Optionally, the demineralization of the calcified tissue residue is carried out for 60-120 minutes. Optionally, the demineralization of the calcified tissue residue is carried out for approximately 60 minutes. If the demineralization process is carried out in a continuous flow process, the length of time that the demineralization is carried out depends on the residence time of the calcified tissue residue in the reaction vessel. The residence time of the calcified tissue residue in the reaction vessel may be controlled by varying the length of the path between the inlet and outlet of the reaction vessel through which the calcified tissue residue must travel. The speed at which the calcified tissue residue travels through the reaction vessel may also determine the duration of the demineralization process. In the case of a rotating drum reaction vessel, the speed at which the calcified tissue residue travels between the inlet and outlet of the drum (i.e., along the axial length of the drum) depends on the rotation speed of the drum. The length of time of the demineralization process should be sufficient to solubilize substantially all of the mineral portion of the calcified tissue residue, but should not be so long that energy is wasted by unnecessarily maintaining the fully demineralized tissue residue in the demineralization process.

[0207] The mineralized tissue that is mixed with the acid in the drum may include a protein portion. Decalcification of the mineralized tissue may be performed until the protein portion of the mineralized tissue is partially or completely separated from the mineral portion of the mineralized tissue.

[0208] The mineralized tissue may be derived from an organic feedstock that is or includes, for example, fish off-cuts (e.g., salmon or cod), or chicken off-cuts, or meat off-cuts, including other animal origin. In particular, the organic feedstock may be derived from waste generated by the food industry, or may be a secondary product of another industrial process. The organic feedstock may include "industrial fish", i.e. the raw material used to produce fishmeal. Thus, the processing may help to utilise discarded products and minimise waste.

[0209] Depending on the organic feedstock, the mineralized tissue present in the organic feedstock may include one or more of bone, fish scales, tendons, cartilage, tooth enamel, dentin, and hoof. Preferably, the mineralized tissue includes bone. The organic feedstock may include meat and bone from an aquatic animal source (e.g., from a marine animal) or a terrestrial animal source.

[0210] The mineralized tissue within the organic feedstock may comprise a protein portion and a mineral portion. If the mineralized tissue is bone, the mineral portion of the mineralized tissue may comprise calcium hydroxyapatite. If the mineralized tissue is bone, the protein portion may comprise ossein (which comprises primarily collagen).

[0211] If the mineralized tissue contains protein moieties, demineralization of the mineralized tissue results in demineralized tissues containing the protein moieties. These demineralized tissues can then be further processed, for example, the demineralized tissues can undergo further enzymatic hydrolysis treatments (e.g., using proteases). Enzymatic hydrolysis of the demineralized tissue can then result in at least a portion of the protein moieties of the demineralized tissue being hydrolyzed.

[0212] Optionally, demineralization of the calcified tissue residue is performed at a temperature between 30 and 70 degrees Celsius. Optionally, demineralization of the calcified tissue residue is performed at a temperature between 40 and 55 degrees Celsius. Optionally, demineralization of the calcified tissue residue is performed at a temperature of approximately 40 degrees Celsius. Thus, the temperature at which demineralization is performed is advantageously elevated to provide energy to the reactants to increase the reaction rate, without causing damage to the reactants or products, and without wasting energy or other resources by raising the temperature unnecessarily high.

[0213] The structural features of the rotating drum apparatus are described above with particular reference to their function when the drum is used in a method for demineralizing calcified tissue residues. When the rotating drum apparatus is used as a reaction vessel for carrying out enzymatic hydrolysis (e.g., in any of the first, second, third, or fourth aspects of the invention), the same structures may also be used for the same or different functionality. For example, the fluid inlets of the rotating drum may be used for different purposes, as discussed in more detail below.

[0214] When the rotating drum apparatus is used as a reaction vessel for carrying out enzymatic hydrolysis, the fluid inlet may allow for the addition of reagents to alter the properties of the material within the drum. The reagents may be solutions such as acids, bases, water, organic solvents, or water containing, for example, salts or buffers.

[0215] The fluid inlet may be positioned to introduce a gas through the fluid inlet into the material in the drum, for example, an inert gas to remove oxygen and other reactive gases from the material being processed.

[0216] The fluid introduced by the fluid inlet may be at a higher or lower temperature compared to the temperature of the material in the drum. In this way, the addition of fluid by the fluid inlet may promote mixing of the material in the drum and may also regulate its temperature. For example, hot water may be added to increase the temperature to promote enzymatic reactions in the rear portion of the drum apparatus or in subsequent processing areas, or hot gas may be bubbled through the material for the same purpose. Alternatively, cold liquid (e.g. water) or cold gas may be introduced to reduce the temperature, e.g., to stop the enzymatic reaction. Similarly, hot liquid or hot gas may be introduced to increase the temperature, e.g., to inactivate / denaturate the enzymes to stop the enzymatic reaction.

[0217] Optionally, steam may be introduced by a fluid inlet through a fluid inlet near the outlet of the drum to stop the enzymatic reaction (by inactivating the enzyme).

[0218] It should be noted that the use of a rotating drum device is suitable for enzymatic processing because it can avoid the formation of emulsions. Avoiding or reducing the formation of emulsions is an important consideration in enzymatic processing systems (e.g., hydrolysis of protein / lipid mixtures). Emulsions block enzymatic access to parts of the feedstock trapped in the emulsion, thus reducing the efficiency of the enzymatic processing. Furthermore, problems with emulsions extend to the separation stage. In emulsions, lipids can be tightly associated with water-soluble components, such as peptide materials, that cannot be separated by mechanical separators. Thus, the result can be, for example, poor separation of lipids in the protein phase and / or proteins in the lipid phase. Although emulsions can be removed by filtration at a later stage, it is still not possible to recover the emulsified components and combine them with the non-emulsified fraction. That is, without specialized equipment, it is not possible to separate the water-soluble components from an emulsion and recombine them with the non-emulsified water-soluble fraction, nor is it possible to separate the lipid and fat-soluble components from an emulsion and recombine them with the non-emulsified lipid and fat-soluble fraction. [Brief description of the drawings]

[0219] Specific embodiments of the present invention will now be described, by way of example only, with reference to the accompanying drawings, in which: [Figure 1] A method for processing organic feedstock containing meat and protein-containing mineralized tissue is presented. [Diagram 2] Another method for processing organic feedstock containing meat and protein-containing mineralized tissue is presented. [Diagram 3] A method for processing organic feedstock containing meat and bones is presented. [Figure 4] FIG. 1 is a schematic diagram showing a first processing plant. [Diagram 5] FIG. 2 is a schematic diagram of a second processing plant. [Figure 6] FIG. 13 is a schematic diagram showing a third processing plant. [Figure 7] FIG. 13 is a schematic diagram showing a fourth processing plant. [Figure 8] FIG. 13 is a schematic diagram showing a fifth treatment plant. [Figure 9] 1 shows a drum that rotates to mix materials within the drum and transport the mix along the length of the drum. [Figure 10] 10 shows a helical blade with mixing device used in the drum of FIG. [Figure 11] FIG. 11 is an enlarged view of a portion of the helical blade of FIG. [Figure 12] FIG. 12 is a further enlarged view of a portion of FIG. [Figure 13] 13 shows possible configurations of a flow diverter for separating the flow of calcified tissue residue. [Figure 14] 14 shows a rotary dosing valve forming part of the flow divider of FIG. 13; DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0220] FIG. 1 illustrates a method for processing organic feedstock, where the organic feedstock includes meat and protein-containing mineralized tissue. Protein-containing mineralized tissue typically includes a proteinaceous organic matrix (i.e., an organic matrix formed primarily from protein) and minerals bound to the proteinaceous organic matrix. Thus, protein-containing mineralized tissue consists primarily of protein and minerals.

[0221] The first step of the process involves the removal of the meat, which leaves behind a protein-containing calcified tissue residue that can be more easily processed subsequently.

[0222] The next step involves demineralization of the protein-containing calcified tissue residue, resulting in the production of solubilized minerals that can be easily separated from the demineralized protein-containing tissue residue.

[0223] The demineralized protein-containing tissue residue can then be further processed to obtain the desired end product (as discussed in detail below).

[0224] In protein-containing calcified tissue, the mineral forms a barrier that prevents (or at least reduces the rate of) chemical reactions involving the protein-organic matrix. Thus, removal of the mineral means that proteins in the demineralized protein-containing tissue residue can react more readily compared to proteins in protein-containing calcified tissue.

[0225] FIG. 2 shows a similar method to that discussed in FIG. 1 (all of the above comments regarding the method in FIG. 1 also apply to the method in FIG. 2), with the only difference being that the method in FIG. 2 specifies that the means of meat removal is enzymatic hydrolysis. Since meat is primarily protein, the enzymes used in the enzymatic hydrolysis process are proteases. Note that enzymatic hydrolysis is primarily a reaction with meat (i.e., hydrolysis of meat). Proteins in protein-containing calcified tissues are not easily hydrolyzed because they are shielded from the enzymatic hydrolysis process by minerals bound within the protein matrix.

[0226] Figure 3 shows a similar process to that discussed in Figure 2, except that in Figure 3 it is specified that the organic feedstock includes meat and bone (all of the comments above regarding the processes of Figures 1 and 2 also apply to the process of Figure 3). In bone, the organic protein matrix constitutes approximately 30-35% of the bone mass and is called ossein. Ossein is roughly 95% collagen (in the form of flexible elastic fibers), which is a protein. The minerals bound in the ossein matrix are primarily calcium phosphates in a chemical arrangement known as calcium hydroxyapatite.

[0227] The first step in the process of Figure 3 involves the removal of the flesh by enzymatic hydrolysis (e.g., using proteases), which leaves behind a protein-containing mineralized tissue residue, namely, mineralized ossein. Removal of the flesh allows the mineralized ossein to be more easily processed subsequently.

[0228] The next step involves demineralization of the calcified ossein, resulting in the production of solubilized minerals that can be easily separated from the ossein.

[0229] The ossein (ie, the demineralized protein-containing tissue residue) can then be further processed to obtain the desired end product (as discussed in detail below).

[0230] In all three of the foregoing methods, some or all of the demineralized protein-containing tissue residue may be further processed, for example, by: - a further step of enzymatic hydrolysis (including, for example, the use of proteases) to hydrolyze the demineralized protein-containing tissue residues; -Drying to form a protein meal.

[0231] Both processes are described in further detail below.

[0232] In all three of the above methods, the mineralized protein-containing tissue residue portion may be further processed, for example, by: - Drying (optionally in a mill dryer).

[0233] In any of the above three methods incorporating one or more steps of enzymatic hydrolysis (optionally using a protease), the hydrolysis fraction may be one of the following fractions: - an aqueous fraction comprising water with dissolved proteins, polypeptides and amino acids (the aqueous fraction may be referred to as a hydrolysate); - a sediment fraction containing, for example, insoluble proteins and other small solids (the sediment fraction may typically contain 30-40% dry matter); and - may contain an oil fraction.

[0234] The hydrolysis fraction may be separated into three component fractions, and each of the aqueous, sediment, and oil fractions may be further processed after separation. The aqueous fraction may be dried. The sediment fraction may be dried. The aqueous and sediment fractions need not be completely dried, but may be partially dried. The aqueous and sediment fractions may be dried to the extent that they are in a form that is stable according to their water activity. For example, the aqueous fraction may be partially dried to form a paste, usually with a dry matter content of more than 60%.

[0235] A schematic diagram of the first processing plant is shown in Figure 4. As seen in Figure 4, the raw material (i.e., organic feedstock containing mineralized tissue) is mixed with water in a first stage 10 and the mixture is then transferred to a first reaction vessel 20 where enzymatic hydrolysis of the organic feedstock is carried out.

[0236] Enzymatic hydrolysis typically involves heating the organic feedstock with water. The process is carried out at a temperature of approximately 55° C. and a pH of approximately pH 6. An enzyme, such as a protease, is added and the solution is mixed for 40 to 120 minutes.

[0237] The output from the hydrolysis of organic feedstock (labeled "a" in FIG. 4) is - an aqueous fraction containing water with dissolved proteins, polypeptides, and amino acids (as well as any molecules dissolved in water); - A precipitate fraction containing insoluble proteins and other small solids; - oil fraction; and - Contains the calcified tissue residue fraction containing larger solids.

[0238] These first two are collectively referred to as the "slurry fraction" and therefore the output from the first reaction vessel 20 comprises a slurry fraction, an oil fraction and a calcified tissue residue fraction.

[0239] The output of the first reaction vessel 20 is received by a first separator 30 configured to separate the calcified tissue residue from the slurry and oil fractions. The first separator 30 comprises a vibrating sieve system. As noted above, the slurry fraction comprises a sediment fraction comprising insoluble proteins and other small solids, where the small solids (and indeed the insoluble proteins) are smaller than the sieve holes so as to pass through the sieve. The aqueous fraction also passes through the sieve, as does the oil fraction.

[0240] The slurry and oil fractions (labeled "b" in FIG. 4) that pass through the first separator 30 are received by the hydrolysis fraction separation vessel 40. In this example, the hydrolysis fraction separation vessel 40 is a three-phase centrifugal decanter, although other configurations are possible (e.g., a two-phase decanter in combination with one or two separators). Whatever the structural configuration, functionally, the hydrolysis fraction separation vessel 40 separates the slurry and oil fractions into: -b1: an aqueous fraction containing water with dissolved proteins, polypeptides, and amino acids; -b2: a sediment fraction containing insoluble proteins and other small solids; and - b3: configured to separate into an oil fraction.

[0241] The mineralized tissue residue fraction retained by the first separator 30, i.e., containing solids too large to pass through the sieve (labeled "c" in FIG. 4), is received by the diverter 50, where a first portion of the mineralized tissue residue fraction (labeled "e" in FIG. 4) is diverted to the dryer 60 and a second portion of the mineralized tissue residue fraction (labeled "d" in FIG. 4) is diverted to the second reaction vessel 70.

[0242] In this example, the first portion of the calcified tissue residue fraction diverted to dryer 60 comprises approximately 60% by weight of the solid fraction. However, this is in no way limiting, and the relative amounts of fractions "e" and "d" may be selected according to the particular biorefinery process and desired end product, and there is no generally applicable ratio.

[0243] Dryer 60 is a mill dryer that simultaneously grinds and dries the solid fraction.

[0244] The second portion of the mineralized tissue remnant fraction comprises the remaining portion of the mineralized tissue remnant fraction after the first portion has been removed, i.e., in this particular non-limiting example, the second portion comprises approximately 40% by weight of the mineralized tissue remnant fraction. The second portion is received by the second reaction vessel 70 and undergoes a demineralization process.

[0245] The demineralization process carried out in the second reaction vessel 70 typically involves heating the mineralized tissue residue with an HCl acid solution at a concentration of approximately 3% by weight. The process is carried out at a temperature of approximately 40° C. The weight ratio of mineralized tissue residue to acid solution is approximately 1:5. The mineralized tissue residue and acid solution are mixed for approximately 60 minutes and then allowed to return to room temperature, i.e. the demineralization process is carried out for approximately 60 minutes.

[0246] The output of the second reaction vessel 70 includes a liquid fraction (labeled "f" in FIG. 4) containing solubilized minerals, and a demineralized tissue residue fraction (labeled "g" in FIG. 4) containing insoluble protein material such as ossein. The liquid fraction (labeled "f" in FIG. 4) of the output of the second reaction vessel 70 is discharged to a drain 80 in this example for collection (solubilized minerals may then be collected and advantageously utilized in further processes or products) or disposal. The solid fraction (labeled "g" in FIG. 4) of the output of the second reaction vessel 70 is directed to a dryer 60.

[0247] Figure 5 shows another processing plant, in which components a, b, c, d, f and g are the same as those described with reference to Figure 4, and the processes carried out by the first reaction vessel 20, the first separator 30, the hydrolysis fraction separation vessel 40 and the second reaction vessel 70 are as described with reference to Figure 4.

[0248] In the processing plant of FIG. 5, the raw material (i.e., organic feedstock containing mineralized tissue) is mixed with water in a first stage 10 and the mixture is transferred to a first reaction vessel 20 where enzymatic hydrolysis of the organic feedstock is carried out as described in connection with FIG. 4.

[0249] Hydrolysis of the organic feedstock results in the formation of the following (labeled "a" in FIG. 5): an aqueous fraction containing water with dissolved proteins, polypeptides, and amino acids; a sediment fraction containing insoluble proteins and other small solids; an oil fraction; and a mineralized tissue residue fraction containing larger solids. The output of the first reaction vessel 20 is received by a first separator 30 which contains a vibrating screen.

[0250] The slurry fraction and oil fraction (labeled "b" in FIG. 5) that pass through the first separator 30 are received by the hydrolysis fraction separation vessel 40 where they are separated into an aqueous fraction containing water with dissolved proteins, polypeptides, and amino acids (labeled "b1"); a sediment fraction containing insoluble proteins and other small solids (labeled "b2"); and an oil fraction (labeled "b3").

[0251] The mineralized tissue residue fraction retained by the first separator 30 (labeled "c" in FIG. 5), i.e., the fraction containing solids too large to pass through the sieve, is received by the diverter 50 and directed to the second reaction vessel 70, where the demineralization process is carried out, as described in connection with FIG. 4. In this embodiment, the diverter does not separate the mineralized tissue residue fraction into separate portions, but simply passes all of the mineralized tissue residue fraction (labeled "d" in FIG. 5) to the second reaction vessel 70. The diverter is present to allow for greater flexibility of the system.

[0252] The effluent of the second reaction vessel 70 comprises a liquid fraction containing solubilized minerals (labeled "f" in FIG. 5) and a demineralized tissue residue fraction containing insoluble protein material such as ossein (labeled "g" in FIG. 5). The liquid fraction (f) of the effluent of the second reaction vessel, in this example, is discharged to a drain 80 for collection (the solubilized minerals may then be collected and advantageously utilized in further processes or products) or disposal.

[0253] The demineralized tissue residue fraction discharged from the second reaction vessel 70 is directed to a third reaction vessel 90, in which enzymatic hydrolysis of the demineralized tissue residue (g) discharged from the second reaction vessel is carried out.

[0254] The enzymatic hydrolysis carried out in the third reaction vessel 90 may be carried out using similar parameters as those described for the enzymatic hydrolysis carried out in the first reaction vessel 20. Alternatively, the exact parameters selected for the second hydrolysis process may be tailored to the reactants involved, i.e., the parameters may be different for the second enzymatic hydrolysis process because the input materials are different (e.g., in the first reaction vessel 20, the feedstock may include meat and bones, whereas in the third reaction vessel 90, the feedstock includes demineralized tissue residues).

[0255] The output of the third reaction vessel 90 (labeled "h" in FIG. 5) contains an aqueous fraction comprising water with dissolved proteins, polypeptides, and amino acids, and a sediment fraction comprising insoluble proteins and other small solids. The output of the third reaction vessel 90 (labeled "h") is received by the hydrolysis fraction separation vessel 40 where it is combined with the fraction labeled "b" described above and separated as discussed above.

[0256] Figure 6 shows another treatment plant, in which components a, b, c, d, f and g are the same as those described with reference to Figure 4, and the process carried out by the first reaction vessel 20, the first separator 30, the hydrolysis fraction separation vessel 40 and the second reaction vessel 70 are as described with reference to Figure 4.

[0257] In the processing plant of FIG. 6, the raw material (i.e., organic feedstock containing mineralized tissue) is mixed with water in a first stage 10 and the mixture is transferred to a first reaction vessel 20 where enzymatic hydrolysis of the organic feedstock is carried out as described in connection with FIG. 4.

[0258] Hydrolysis of the organic feedstock results in the formation of the following (labeled "a" in FIG. 6): an aqueous fraction containing water with dissolved proteins, polypeptides, and amino acids; a sediment fraction containing insoluble proteins and other small solids; an oil fraction; and a mineralized tissue residue fraction containing larger solids.

[0259] The output of the first reaction vessel is received by a first separator 30 including a vibrating screen configured to separate the calcified tissue residue fraction from the remainder of the material output from the first reaction vessel 20.

[0260] The slurry fraction and oil fraction (labeled "b" in FIG. 6) that pass through the first separator 30 are received by the hydrolysis fraction separation vessel 40 where they are separated into an aqueous fraction containing water with dissolved proteins, polypeptides, and amino acids (labeled "b1"); a sediment fraction containing insoluble proteins and other small solids (labeled "b2"); and an oil fraction (labeled "b3").

[0261] The mineralized tissue residue fraction retained by the first separator 30 (labeled "c" in FIG. 6), i.e., solids too large to pass through the sieve, is received by the diverter 50 and directed to the second reaction vessel 70, where the demineralization process is carried out, as described in connection with FIG. 4. In this embodiment, the diverter does not separate the mineralized tissue residue fraction into multiple portions, but is present for flexibility of the system.

[0262] The effluent of the second reaction vessel 70 comprises a liquid fraction comprising solubilized minerals (labeled "f" in FIG. 6) and a demineralized tissue residue fraction comprising insoluble protein material (labeled "g" in FIG. 6). The liquid fraction (f) of the effluent of the second reaction vessel is sent to a drain 80 for collection (from which the solubilized minerals may then be collected and advantageously utilized in further processes or products) or disposal.

[0263] The demineralized tissue residue fraction (g) discharged from the second reaction vessel 70 is directed to and received by the first reaction vessel 20. The demineralized tissue residue is then subjected to a further hydrolysis process to obtain further proteins, polypeptides and amino acids. In this way, the demineralized tissue residue is recycled to the first reaction vessel 20 and incorporated into further raw materials (organic feedstock containing mineralized tissue and water). The hydrolysis of the demineralized tissue residue in the first reaction vessel 20 may be more complete than the hydrolysis of the original mineralized tissue residue in the first pass to the reaction vessel 20. Due to the recycling and rehydrolysis of the material, a higher yield of the desired end product may be achieved.

[0264] Figure 7 shows another treatment plant, in which components a, b, c, d, f and g are the same as those described with reference to Figure 4, and the process carried out by the first reaction vessel 20, the first separator 30, the hydrolysis fraction separation vessel 40 and the second reaction vessel 70 are as described with reference to Figure 4.

[0265] In the processing plant of FIG. 7, the raw material (i.e., organic feedstock containing mineralized tissue) is mixed with water in a first stage 10 and the mixture is then transferred to a first reaction vessel 20 where enzymatic hydrolysis of the organic feedstock is carried out as described in connection with FIG. 4.

[0266] Hydrolysis of the organic feedstock in the first reaction vessel 20 results in the formation of the following (labeled "a" in FIG. 7): an aqueous fraction containing water with dissolved proteins, polypeptides, and amino acids; a sediment fraction containing insoluble proteins and other small solids; an oil fraction; and a calcified tissue residue fraction containing larger solids.

[0267] The output of the first reaction vessel is received by a first separator 30 including a vibrating screen configured to separate the calcified tissue residue fraction from the remainder of the material output from the first reaction vessel.

[0268] The slurry fraction and oil fraction (labeled "b" in FIG. 7) that pass through the first separator 30 are received by the hydrolysis fraction separation vessel 40 where they are separated into an aqueous fraction containing water with dissolved proteins, polypeptides, and amino acids (labeled "b1"); a sediment fraction containing insoluble proteins and other small solids (labeled "b2"); and an oil fraction (labeled "b3").

[0269] The mineralized tissue residue fraction retained by the first separator 30 (labeled "c" in FIG. 7), i.e., the fraction containing solids too large to pass through the sieve, is received by the diverter 50 and directed to the second reaction vessel 70, where the demineralization process is carried out, as described in connection with FIG. 4. In this embodiment, the diverter does not separate the mineralized tissue residue fraction into multiple portions, but is present for flexibility of the system.

[0270] The effluent of the second reaction vessel 70 includes a liquid fraction (labeled "f") containing solubilized minerals, and a demineralized tissue residue fraction (labeled "g") containing insoluble protein material. The liquid fraction (f) of the effluent of the second reaction vessel is directed to a drain 80 for collection (from which the solubilized minerals may then be collected and advantageously utilized in further processes or products) or disposal.

[0271] The demineralized tissue residue fraction (g) discharged from the second reaction vessel 70 is directed to and received by the dryer 100. The demineralized tissue residue fraction of the discharge of the second reaction vessel 70 is dried to obtain a protein meal 110, such as a collagen meal.

[0272] Figure 8 shows an alternative treatment plant, in which components a, b, c, d, f, g and h are the same as those described with reference to Figures 4 and 5, and the process carried out by the first reaction vessel 20, the first separator 30, the hydrolysis fraction separation vessel 40 and the second reaction vessel 70 is as described with reference to Figure 4.

[0273] In the processing plant of FIG. 8, the raw material (i.e., organic feedstock containing mineralized tissue) is mixed with water in a first stage 10 and the mixture is transferred to a first reaction vessel 20 where enzymatic hydrolysis of the organic feedstock is carried out as described in connection with FIG. 4.

[0274] Hydrolysis of the organic feedstock in the first reaction vessel 20 results in the formation of the following (labeled "a" in FIG. 8): an aqueous fraction containing water with dissolved proteins, polypeptides, and amino acids; a sediment fraction containing insoluble proteins and other small solids; an oil fraction; and a calcified tissue residue fraction containing larger solids.

[0275] The output of the first reaction vessel 20 is received by a first separator 30 including a vibrating screen configured to separate the calcified tissue residue fraction from the remainder of the material output from the first reaction vessel 20.

[0276] The slurry fraction and oil fraction (labeled "b" in FIG. 8) that pass through the first separator 30 are received by a hydrolysis fraction separation vessel 40 where they are separated into an aqueous fraction (labeled "b1") comprising water with dissolved proteins, polypeptides, and amino acids; a sediment fraction (labeled "b2") comprising insoluble proteins and other small solids; and an oil fraction (labeled "b3"). The sediment fraction (labeled "b2") comprising insoluble proteins and other small solids is then directed to a dryer 120 to form a protein meal comprising insoluble proteins.

[0277] The mineralized tissue residue fraction retained by the first separator 30 (labeled "c" in FIG. 8), i.e., solids too large to pass through the sieve, is received by the diverter 50 and directed to the second reaction vessel 70, where the demineralization process is carried out, as described in connection with FIG. 4. In this embodiment, the diverter does not separate the mineralized tissue residue fraction into multiple portions, but is present for flexibility of the system.

[0278] The effluent of the second reaction vessel 70 comprises a liquid fraction (labelled "f") comprising solubilised minerals, and a demineralised tissue residue fraction (labelled "g") comprising insoluble protein material. The liquid fraction (f) of the effluent of the second reaction vessel 70 is discharged to a drain 80 for collection (from which the solubilised minerals may then be collected and advantageously utilised in further processes or products) or disposal.

[0279] The demineralized tissue residue fraction (g) discharged from the second reaction vessel 70 is directed to and received by the third reaction vessel 90, where the demineralized tissue residue undergoes a further enzymatic hydrolysis process. The enzymatic hydrolysis performed in the third reaction vessel 90 may be performed using similar parameters as those described for the enzymatic hydrolysis performed in the first reaction vessel 20. Alternatively, the exact parameters selected for the second hydrolysis process may be tailored to the reactants involved. That is, the parameters may be different for the second enzymatic hydrolysis process because the input materials are different (e.g., in the first reaction vessel 20, the feedstock may include meat and bones, while in the third reaction vessel 90, the feedstock includes demineralized tissue residue).

[0280] The output of the third reaction vessel 90 (labeled "h") contains an aqueous fraction (labeled "h1") comprising water with dissolved proteins, polypeptides, and amino acids, and a sediment fraction (labeled "h2") comprising insoluble proteins and other small solids. The output of the third reaction vessel 90 (labeled "h") is then received by a second separator 130, where the sediment fraction (h2) comprising insoluble proteins and other small solids is separated from the aqueous fraction (h1).

[0281] The precipitate fraction (labeled "h2") containing insoluble protein and other small solids is directed to and received by dryer 120 (along with fraction b2 described above), where it is dried to form a protein meal containing insoluble protein.

[0282] The aqueous fraction (labeled "h1") comprising water with dissolved proteins, polypeptides, and amino acids is received by the evaporator 140 configured to dry the aqueous fraction. The evaporated gas portion is directed to the condenser 150 from which the condensate (labeled "i") is poured off for collection or disposal. The paste (labeled "j") obtained from the evaporation process can be collected as a peptide paste 170. As an example, the peptide paste is a collagen peptide paste. Here, it should be understood that the collagen peptide paste does not contain collagen (because collagen was hydrolyzed in the second enzymatic hydrolysis process carried out in the third reaction vessel 90), but instead contains collagen derivatives, i.e. proteins, polypeptides, and amino acids obtained from the hydrolysis of collagen.

[0283] A percentage of the peptide paste (0%-100%) may be directed to the spray dryer 160 to produce peptide powder 180. As an example, the peptide powder is collagen peptide powder (containing proteins, polypeptides, and amino acids obtained from the hydrolysis of collagen). The percentage of the peptide paste that is directed to the spray dryer 160 to produce the peptide powder depends solely on the desired yield of each product.

[0284] 9-12 show rotatable drums that may be used in a rotary drum apparatus for mixing and conveying raw materials, such as for mixing raw materials / reactants for the enzymatic hydrolysis and de-ashing process described above.

[0285] As can be seen in FIG. 9, the rotatable drum has a cylindrical shape with an outer wall formed as a cylindrical tube 212. In use, the drum is arranged such that its axis of rotation extends along the horizontal. An inlet for the flow of reactants is located at a first end of the drum and an outlet is located at a second end of the drum downstream of the inlet. The reactants are transported along the axial length of the drum from the inlet to the outlet. A screw including a helical blade 214 is provided within the cylindrical tube 212, the outer edge of the helical blade 214 being fixed to the inner wall of the cylindrical tube 212. This may be done, for example, by welding. Ensuring that a watertight seal is formed between the outer edge of the helical blade 214 and the inner wall of the cylindrical tube 212 is beneficial as it means that a plurality of chambers 216 may be formed. The chambers 216 are formed between two adjacent turns of the helical blade 214. The chamber opens to a flow passage that extends axially through the center of the drum above the level of the helical blade 214 (the helical blade does not extend along the entire radius of the drum).

[0286] The helical blade 214 of the drum shown in Figures 9 and 10 has a constant pitch throughout the length of the drum so that the chamber formed between each turn of the blade maintains a constant volume. In other designs, the pitch of the helical blade may vary along the length of the drum. In particular, the pitch may increase from the inlet to the outlet so that the volume of the chamber between the turns also increases from the inlet to the outlet.

[0287] A plurality of mixing devices 218 are provided on the outer edge surface of the helical blade 214. There are a plurality of mixing devices 218 for each turn of the helical blade 214, and as shown in this example, there may be eight for each turn of the helical blade 214.

[0288] The mixing devices 218 and helical blades 214 can be seen more clearly in Figure 10, where the cylindrical tube 212 has been removed for clarity. Figure 10 also shows the piping used to supply fluid to the mixing devices 218, including a central supply pipe 220 and branch pipes 222 that extend to each individual mixing device 218. The central supply pipe 220 may be connected to a rotary valve (not shown) for directing fluid into the drum as it rotates.

[0289] The mixing devices 218 will now be described in more detail with reference to Figures 11 and 12. Figure 11 shows a close-up of a portion of two turns of the helical blade 214, with one of the mixing devices 218 at the top of the figure shown in partial cross-section. Figure 12 shows a close-up of the top of Figure 11 so that further detail can be seen. Each of the mixing devices 218 includes a wedge-shaped mixing vane and a fluid inlet. The mixing vane in this example has a side profile in the shape of a right-angled triangle, with one surface of the triangle bonded to the surface of the helical blade 214, a vertical surface of the triangle extending at a right angle from the surface of the helical blade 214, and an inclined surface of the triangle providing the mixing vane surface. The inclined surface of the triangle extends from a forward edge at the narrow point of the triangle to a rear edge at the apex of the triangle furthest from the helical blade 214. The rear edge of the mixing vane is provided with a fluid inlet 24, and fluid is supplied via a pipe 220 and a branch pipe 222, which conveys the fluid from the inlet 24 through the mixer 218 and into the rotating drum.

[0290] The use of such a rotating drum in the demineralization process will now be described in more detail. Advantageously, the demineralization process is carried out with a rotating drum operating in a "submerged" mode. Here, the level of the reactants is above the top of the helical blades 214, so that the acid solution can overflow from each of the separate volumes 216 and flow through an open channel in the center of the drum from the inlet to the outlet of the drum. However, the solid parts of the organic feedstock (including mineralized tissues such as bones, and / or other animal parts such as fish scales, hooves, etc.) sink to the base of the drum, so that the solid parts remain in their separated volumes between the walls of the blades. Thus, the acid in the chambers of the drum overflows into the subsequent chambers in the direction of the outlet, causing an increase in the flow of the acid solution in the direction of the outlet of the drum. This allows the supply of fresh acid to the chambers of the drum towards the outlet. The flow of the acid solution helps to replenish the consumed acid in the chambers towards the outlet of the drum, thus maintaining the demineralization reaction rate along the length of the drum.

[0291] The residence time of the mineralized tissue is not affected by the use of a submerged design, but instead remains controlled by the rotation of the drum. By modifying the process to replenish reactive acid along the length of the drum, demineralization can be completed in less time and over a correspondingly shorter length of drum. As a result, the drum can be made smaller.

[0292] Advantageously, the ratio of acid solution to mineralized tissue increases along the length of the drum from the drum inlet to the drum outlet. The gradual increase in acid allows the demineralization rate to be controlled. For example, acid consumed through the demineralization process occurring in the chamber toward the drum inlet can be replenished as reactants are conveyed toward the drum outlet to provide a more constant volume of reactive acid along the length of the drum, thus approaching a more constant demineralization rate throughout the process. The addition can be empirically optimized for a given raw material and equipment configuration. By modifying the process to increase the ratio of acid solution along the length of the drum, thereby increasing the reaction rate versus keeping the ratio constant, demineralization can be completed in a shorter time and over a correspondingly shorter length of the drum. As a result, the drum can be made smaller.

[0293] In some embodiments, the pitch of the helical blade increases along the length of the drum from the drum inlet to the drum outlet. Thus, each chamber increases in volume toward the drum outlet. Since the mineralized tissue remains at the base of the drum and is separated by the walls of the blade, the volume of tissue in each chamber remains constant as the tissue progresses through the drum. However, given that all chambers are filled to the same level, the volume of acid solution in each chamber increases along the length of the drum as the pitch of the helical blade increases in response to the increase in the volume of the chamber. Thus, the ratio of acid solution to mineralized tissue increases along the length of the drum. This has the advantage of increasing the presence of reactive acid compared to consumed acid, thus helping to maintain the desired reaction rate.

[0294] 13 and 14 show a schematic representation of a component suitable for use as a flow splitter 300 for splitting the flow of calcified tissue residue into two streams. Here, the flow splitter 300 is provided by a combination of a screw conveyor 310 and a rotary dosing valve 320. The calcified tissue residue moves along the screw conveyor 310, under which the rotary dosing valve 320 is mounted. A part of the calcified tissue residue is diverted from the main flow by the rotary dosing valve 320, while the remainder of the calcified tissue residue is further transported by the conveyor 310. The flow splitter 300 thus splits the flow of calcified tissue residue into two parts in a non-selective manner. The relative sizes of the two split streams are set by the rotational speed of the rotary dosing valve 320.

[0295] 14, the rotary dosing valve 320 includes an inlet 321 and an outlet 325. Between them is a valve chamber with a number of vanes 322 extending from a rotatable hub 323. The vanes divide the valve chamber into a number of pockets 324. The faster the vanes 322 rotate around the hub 323, the faster the material moves from the inlet 321 to the outlet 325. In other words, a greater portion of the material can be diverted from the main flow.

[0296] The details of the present invention will now be described in further detail in the following non-limiting examples.

[0297] Example 1 - Decalcification of calcified tissue residues Salmon bones were hydrolyzed and the solid residue (calcified tissue residue) was analyzed. Salmon bone residue from 100 g hydrolysis was found to contain 31.5 g ash and 18.5 g protein.

[0298] Salmon bone residue (mineralized tissue residue) from 100 g of hydrolysis was combined with aqueous HCl in the proportions listed in Table 1. The reactions were carried out for the times and at the specified temperatures listed in Table 1. The remaining solids were collected by vacuum filtration and rinsed with 500 mL tap water. The solids were freeze-dried prior to analysis and analyzed to determine the remaining mineral content.

[0299] The data demonstrate that mineralized tissue residues collected after hydrolysis of salmon bones can be effectively demineralized using hydrochloric acid. For example, in run 6 (reaction time 60 min, 40°C, 3% HCl, 1 part bone to 5 parts acid solution), over 90% of the ash was removed.

[0300] Example 2 - Decalcification of bone and mineralized tissue residues Bone and 3% aqueous HCl were combined in the amounts listed in Table 2 and heated for the times and temperatures listed. The mixture was then vacuum filtered and the collected solid was freeze-dried prior to analysis.

[0301] Salmon bones are the bone residues following enzymatic hydrolysis of salmon fillets. Cod bones were produced by soaking cod skeletons in hot water, then mechanically removing the muscle, then rinsing with tap water. The remaining bones were crushed (to a particle size of approximately 3 x 6 mm) and then freeze-dried.

[0302] The data demonstrate that minerals can be effectively removed from cod bones and chicken bones, and from calcified tissue residues from enzymatic hydrolysis of salmon fillets.

[0303] Example 3 - Pilot study of bone demineralization in a rotating drum After hydrolysis of salmon bones in a rotating drum, the mineralized tissue residue (bone) was separated from the other hydrolysis fractions. The bones were then fed again to the rotating drum with 3% HCl to undergo demineralization for 2 hours. The differences in amino acid, dry matter, ash, crude protein, and fat content between the mineralized bone (starting material) and after 2 hours of demineralization (demineralized tissue residue, i.e., ossein) are shown in Table 3. Ash was reduced from 31.9% in the mineralized bone (starting material) to 3.5% in the demineralized tissue residue (ossein) after 2 hours of demineralization. At the same time, the relative crude protein content increased to 23.7% in the demineralized tissue residue (ossein) compared to 18.8% (wet weight basis) in the starting material. The relative increase in crude protein after demineralization was confirmed by amino acid analysis, which showed that the amino acid content in the demineralized tissue residue (ossein) increased by an average of 2.4 (on a dry matter basis) compared with mineralized bone.

[0304] Example 4 - Enzymatic hydrolysis of decalcified tissue residues 200 g of ossein (acid-treated salmon bone fragments) and 600 g of tap water were combined in a glass reactor. The pH was 3.4. To this, 18.0 mL of 3.0 M NaOH (aq) was added to adjust the pH to 6. The mixture was heated to 55°C (approximate heating time 12 minutes) and the enzymes were added as listed in Table 4. The mixture was stirred at 55°C for 60-120 hours. The mixture was then heated to 90°C in a microwave oven and held at that temperature for 10 minutes to denature the enzymes. After cooling to room temperature in an ice bath, the remaining solids were collected by vacuum filtration (Whatman 589 / 1 filter). The masses of the filter cake and filtrate were recorded. The solids were lyophilized and weighed again before analysis. The filtrate was analyzed without further purification or concentration.

[0305] For comparison, 76.62 g of starting material (ossein) was lyophilized to yield 24.19 g of dry material containing 6.4% hydroxyproline, 86.1% protein (N x 6.25), and 98.5% dry matter. Thus, 200 g of ossein starting material contains 63.2 g dry matter, 54.5 g protein, and 4.04 g hydroxyproline.

[0306] The data show that the yield of soluble protein after hydrolysis of ossein is approximately 40% and that all of the ossein protein can be recovered.

[0307] Example 5 - Enzymatic hydrolysis of calcified tissue residues Salmon fillets were stored frozen for approximately 2 months and then ground using a meat grinder immediately prior to use. 250 g of ground salmon fillets, 6.25 g of ossein (acid-treated bone residue), and 250 g of tap water were combined in a glass reactor. The mixture was heated to 55°C (heating time approximately 12 min) and enzymes were added as indicated in the table. The mixture was stirred at 55°C for 60-120 h. The reaction was then heated to 90°C in a microwave oven. After cooling to room temperature in an ice bath, the mixture was centrifuged (20 000×g, 25 min). The liquid fraction was decanted from the sediment and the mass of the wet sediment was recorded. The aqueous and oil layers were separated in a separatory funnel. The oil fraction was discarded and the mass of the aqueous fraction was recorded. The aqueous fraction was filtered through a coffee filter to remove small amounts of sediment and then stored frozen until analysis. The sediment was freeze-dried prior to analysis. The analytical results of the aqueous fraction are shown in Table 5a, while the analytical results of the precipitate fraction are shown in Table 5b.

[0308] Example 6 - Rotating Drum Basic Example Data: Capacity: Approximately 30m per hour 3 (15 tons of raw materials and 15 tons of water) Processing time: 1 hour Density: 1000kg / m 3 Drum diameter: 3.5m Drum diameter inner opening: 1 meter Drum length: 11.75m Spiral blade pitch: 0.375m

[0309] Calculations with "Solidworks" show that an outer diameter of 3.5m, length of 11.75m, inner opening of 1m and 15cm between the liquid level and the top of the screw blades (excluding the volume of the screw blades and mixing flights) gives a total liquid volume of 30,421 litres.

[0310] The slope of the screw is related to the rotational speed of the drum. A high slope gives less "chamber" and a more "batch-like" process. An exemplary configuration (in this example) with 750 mm flight spacing at 1 / 4 revolution / min rotation gives a peripheral speed of 0.0458 m / s.

[0311] Nozzles are integrated within each flight as fluid inlets to feed fluid into the rotating drum during mixing. The angled flight moves particles away from the surface of the screw blade, which continues to rotate and the particles are "fired" from the trailing edge of the flight, after which turbulent mixing occurs. When the next flight contacts the material in the drum, the particles within the material approach the screw blade again (calculated depending on the space between the screw blade and the flight size in each case). Having nozzles along the edge of the flight promotes very effective mixing as the fluid is injected into the turbulent mixing zone.

[0312] The blade in this example may have a height of 500mm, with nozzles mounted at 50, 150, 250, 350, and 450mm from the outer wall of the drum. The maximum height of the liquid in the drum is 1.1m, but the blade height is 500mm rather than the full range of the screw blade or liquid level due to particle agglomeration near the bottom of the rotating drum.

[0313] One nozzle typically delivers 10 liters per hour. With 8 vanes with 5 nozzles each per revolution, you get a total of (8 x 15 x 10) = 600 nozzles. Active nozzles (activated only when submerged in water) make up 38%, i.e. 600 x 0.38 = 228 active nozzles per hour run.

[0314] If we expect the nozzle to spray 10 l / hr, this means that the water addition is 228 x 10 = 2280 l / hr. This results in a 7.6% volume increase, i.e. an increase in liquid level of approximately 6 cm for the chamber at the outlet end of the drum compared to the inlet end. A stable level could be obtained by a small and steady increase in the pitch of the screw blades along the length of the drum.

[0315] Example 7 - Acid Treatment of Bones 100 g of salmon bone fragments (recovered from enzymatic hydrolysis of ground salmon fillets and stored frozen) were combined with 500 g of aqueous acid solution as shown in Table 6. The mixture was vigorously stirred at 40° C. for 2 hours. The mixture was vacuum filtered through Whatman 589 / 1 filter paper and the filter cake was washed three times with 300 mL of water. When water no longer passed through the filter, a sample was collected, weighed, and submitted for analysis. As shown in Table 6, HCL was the most effective acid in removing minerals from bone protein (ossein) in a dose-dependent manner.

[0316] Comparative Example - Attempt to recover protein from bone by enzymatic hydrolysis without demineralization The aim of this example was to test whether proteins (collagen) in salmon bone (which had undergone a first hydrolysis process) could be solubilized by P648L (a protease) by a second hydrolysis process without carrying out demineralization.

[0317] Second hydrolysis conditions: -pH=natural (unadjusted) -Temperature: 70℃ - Water / salmon ingredient ratio: 1.35 - Protease solution to bone ratio: 0.7mL P648L / 100g bone (7000ppm) -Hydrolysis time: 16 hours

[0318] Two parallel experiments were performed: 1. Hydrolyzed salmon bones – no enzyme added (salmon blank). 2. Hydrolyzed salmon bone – supplemented with P648L

[0319] The results are shown in Table 7. The protein yield in the aqueous fraction after the second hydrolysis was 27% (rather low). From Table 4, the corresponding yield from demineralized bone using the same enzyme (P648, runs 1 and 2) was 37-43%, although the runs shown in Table 4 used less protease. Thus, protein recovery is improved for demineralized bone compared to mineralized bone, even when less protease (2000 ppm) was used.

[0320] [Table 1]

[0321] [Table 2]

[0322] [Table 3]

[0323] [Table 4]

[0324] [Table 5]

[0325] [Table 6]

[0326] [Table 7]

[0327] [Table 8]

Claims

1. 1. A method for processing an organic feedstock containing calcified tissue, comprising: conducting enzymatic hydrolysis of the organic feedstock to produce a hydrolyzed fraction and a calcified tissue residue; separating the calcified tissue residue from the hydrolyzed fraction; demineralizing the calcified tissue residue to produce solubilized minerals and demineralized tissue residue; and performing a second enzymatic hydrolysis process on a portion of the demineralized tissue residue.

2. The mineralized tissue comprises bone, the bone comprises a protein portion and a mineral portion, the protein portion comprising ossein, which primarily comprises collagen; 10. The method of claim 1, further comprising separating the effluent of the second enzymatic hydrolysis process into a sediment fraction and an aqueous fraction, the aqueous fraction comprising dissolved proteins, polypeptides, and amino acids derived from the hydrolysis of collagen.

3. 10. The method of claim 1, wherein the organic feedstock comprises meat and bone from aquatic or terrestrial animals.

4. The method of claim 1, wherein the enzymatic hydrolysis of the organic feedstock is carried out in a first reaction vessel; decalcification of the calcified tissue residue is carried out in a second reaction vessel; (i) providing a portion of the decalcified tissue residue into the first reaction vessel; and / or (ii) providing a portion of the decalcified tissue residue to a third reaction vessel to perform enzymatic hydrolysis of the decalcified tissue residue; The method of claim 1 further comprising:

5. 10. The method of claim 1, wherein said processing of said organic feedstock is carried out as a continuous process.

6. 10. The method of claim 1, wherein decalcifying the calcified tissue residue comprises treating the calcified tissue residue with an acid solution to solubilize the minerals.

7. The method of claim 6 , wherein the acid solution comprises hydrochloric acid.

8. The method of claim 6, wherein the acid solution comprises an acid at a concentration of 1 to 5% by weight.

9. The method described in claim 6, wherein the weight ratio of the calcified tissue residue to the acid solution is 1:2 to 1:

8.

10. 7. The method of claim 6, wherein demineralizing the calcified tissue residue comprises adding acid in stages to control the rate of demineralization.

11. 10. The method of claim 1, wherein the decalcification of the calcified tissue residue is carried out for 30 to 180 minutes.

12. 10. The method of claim 1, wherein the decalcification of the calcified tissue residue is carried out at a temperature of 30 to 70 degrees Celsius.

13. 10. The method of claim 1, further comprising separating the solubilized minerals from the demineralized tissue residue.

14. 14. The method of claim 13, further comprising recovering the solubilized minerals by neutralizing the solution of solubilized minerals, optionally using NaOH or KOH, and then treating the neutralized solution, optionally by filtration or centrifugation, to form a mineral slurry.

15. 14. The method of claim 13, wherein separating the mineralized tissue residue from the hydrolysis fraction is performed using a sieve, a dewatering screw press, a filter, or a density separator.

16. 10. The method of claim 1, further comprising separating the hydrolyzed fraction into an aqueous fraction comprising water with dissolved proteins, polypeptides, and amino acids, a sediment fraction comprising insoluble proteins, and an oil fraction.

17. The method of claim 1, wherein the second enzymatic hydrolysis process includes the use of a protease.

18. 18. The method of claim 17, comprising separating the effluent of the second enzymatic hydrolysis process into a sediment fraction and an aqueous fraction, and at least partially drying the sediment fraction and / or the aqueous fraction.

19. 10. The method of claim 1, further comprising recycling a portion of the demineralized tissue residue back into the organic feedstock for enzymatic hydrolysis.

20. 10. The method of claim 1, comprising drying a portion of the decalcified tissue residue and / or drying a portion of the calcified tissue residue.

21. The enzymatic hydrolysis of the organic feedstock and / or the demineralization of the mineralized tissue residue is carried out in a rotating drum reactor, the rotating drum reactor comprising: a drum, rotatable about a central longitudinal axis of said drum, optionally said central longitudinal axis being substantially horizontal; an inlet at a first point on the drum; a screw within the drum, the screw including a helical blade extending along the length of the drum, the outer edge of the helical blade being secured to the inner surface of the drum so that the material may be transported and mixed by the helical blade as the drum rotates; 10. The method of claim 1, further comprising: an exit at a second point along the drum.

22. 10. The method of claim 1, further comprising comminuting the organic feedstock prior to performing the enzymatic hydrolysis.

23. 1. A processing plant for processing organic feedstock containing calcified tissue, comprising: a first reactor vessel configured to carry out enzymatic hydrolysis of the organic feedstock; a first separator configured to receive an output from the first reaction vessel, the first separator for separating calcified tissue residue discharged from the first reaction vessel from a hydrolysis fraction discharged from the first reaction vessel; a second reaction vessel configured to perform demineralization of the mineralized tissue residue to produce demineralized tissue residue and solubilized minerals; A treatment plant having the following characteristics (i) and / or (ii): (i) the first reaction vessel is configured to receive a portion of the decalcified tissue residue discharged from the second reaction vessel; (ii) providing a third reaction vessel for performing a second enzymatic hydrolysis process on a portion of the demineralized tissue residue; 24. The mineralized tissue comprising bone, the bone comprises a protein portion and a mineral portion, the protein portion comprising ossein, which primarily comprises collagen; the first reaction vessel is configured to receive a portion of the decalcified tissue residue discharged from the second reaction vessel; and a three-phase separator for separating the hydrolyzed fraction into an aqueous fraction comprising water having dissolved proteins, polypeptides, and amino acids, a sediment fraction comprising insoluble proteins, and an oil fraction; 24. The treatment plant of claim 23, wherein the aqueous fraction comprises dissolved proteins, polypeptides, and amino acids derived from the hydrolysis of collagen.

25. The mineralized tissue comprising bone, the bone comprises a protein portion and a mineral portion, the protein portion comprising ossein, which primarily comprises collagen; a third reaction vessel for performing the second enzymatic hydrolysis process on a portion of the demineralized tissue residue; and a second separator for separating the effluent of the third reactor vessel into a sediment fraction and an aqueous fraction; 24. The treatment plant of claim 23, wherein the aqueous fraction comprises dissolved proteins, polypeptides, and amino acids derived from the hydrolysis of collagen.

26. 24. The processing plant of claim 23, wherein the processing plant is configured to carry out the processing of the organic feedstock as a continuous process.

27. 24. The processing plant of claim 23, comprising a sieve, dewatering screw press, filter, or density separator for separating the calcified tissue residue from the hydrolysis fraction.

28. 24. The treatment plant of claim 23, comprising a separator for separating the solubilized minerals from the demineralized tissue residue.

29. 24. The processing plant of claim 23, comprising one or more dryers, said one or more dryers comprising a mill dryer and / or an evaporator and / or a spray dryer.

30. A treatment plant as described in claim 23, comprising a flow divider configured to divide the flow of the calcified tissue residue or the decalcified tissue residue into multiple flows.

31. At least one of the first, second, and third reaction vessels is a rotary drum reactor, the rotary drum reactor comprising: a drum rotatable about a central longitudinal axis of said drum, optionally said central longitudinal axis being substantially horizontal; an inlet at a first point on the drum; a screw within the drum, the screw including a helical blade extending along the length of the drum, the outer edge of the helical blade being secured to an inner surface of the drum such that the helical blade can transport and mix materials as the drum rotates; and an outlet at a second point along the drum.

32. A treatment plant according to claim 23, configured to carry out a method according to any one of claims 1 to 22.

33. 1. A method for decalcifying calcified tissue, comprising: mixing the calcified tissue with an acid solution to solubilize minerals in the calcified tissue; The mixing of the mineralized tissue with the acid solution is performed in a rotating drum reactor, the rotating drum reactor comprising: a drum, the drum being rotatable about a central longitudinal axis of the drum; an inlet at a first point on the drum; a screw within the drum, the screw including a helical blade extending along the length of the drum, the outer edge of the helical blade being secured to an inner surface of the drum such that the helical blade can transport and mix materials as the drum rotates; and an exit at a second point along the drum.

34. 34. The method of claim 33, wherein the method is carried out as a continuous process.

35. 35. The method of claim 33 or 34, wherein the axis of rotation of the drum is substantially horizontal.

36. 34. The method of claim 33, wherein the inner edges of the helical blades of the screw are attached, optionally in a watertight manner, to a cylinder along the center of the drum.

37. 34. The method of claim 33, wherein the helical blade extends from the inner surface of the drum toward the center of the drum, but does not extend along the entire diameter of the drum such that an open flow path extends along the axial length of the drum.

38. 38. The method of claim 37, wherein the acid solution fills the rotating drum reactor above the level of the helical blades and allows the acid solution to flow along the open flow path.

39. The method of claim 33, wherein the ratio of the acid solution to the calcified tissue increases along the length of the drum from the inlet to the outlet.

40. 34. The method of claim 33, wherein the pitch of the helical blade increases toward the outlet of the drum.

41. The method of claim 33, wherein the acid solution can be introduced into the drum through fluid inlets spaced along the axial length of the drum.

42. 34. The method of claim 33, wherein the acid solution comprises hydrochloric acid.

43. 34. The method of claim 33, wherein the acid solution comprises an acid at a concentration of 1 to 5% by weight.

44. 34. The method of claim 33, wherein the weight ratio of the calcified tissue residue to the acid solution is 1:2 to 1:

8.

45. 34. The method of claim 33, wherein the decalcification of the calcified tissue residue is carried out for 30 to 180 minutes.

46. 34. The method of claim 33, wherein the decalcification of the calcified tissue residue is carried out at a temperature of 30 to 70 degrees Celsius.

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