Hydrolysate with high free amino acid content and method for producing same, composition, complete feed for animal feed and raw material containing said hydrolysate

Abstract

To provide a composition having high free amino acid content, and a perfect feed and a starting material for an animal feed.SOLUTION: Keratin hydrolysate contains at least 94 wt.%, preferably at least 96 wt.%, more preferably 100 wt.% of free amino acid with respect to the total weight of amino acid of hydrolysate, and contains at least the following amino acid: at least 93 wt.%, preferably at least 95 wt.% of free form valine with respect to the total weight of valine in hydrolysate; at least 90 wt.%, preferably at least 95 wt.% of free form isoleucine with respect to the total weight of isoleucine in hydrolysate; and at least 95 wt.%, preferably 100 wt.% of free form leucine with respect to the total weight of leucine in hydrolysate.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to the field of compositions with a high free amino acid content, in particular obtained from keratin hydrolysates, and their use as complete feeds and starting materials for animal feed.

[0002] Amino acid-based compositions are used in very diverse fields such as nutraceutics, cosmetics and human and animal nutrition, for a wide variety of specific applications in each of these fields. Particular mention may be made of the uses aimed at hair growth and lustre, improving sleep and reducing stress, as well as the uses aimed at re-balancing essential amino acids and as a source of protein in infant nutrition and in canine and feline nutrition.

[0003] One method of obtaining amino acid-based compositions is to produce a hydrolysate of a keratin material.

[0004] Natural keratinous materials mainly contain high molecular weight polypeptides with a highly cross-linked structure that makes them difficult to access for enzymes. This natural keratinous material is poorly digestible. However, it is known that hydrolysis of keratinous materials into amino acids makes it possible to improve the digestibility of said keratinous materials.

[0005] In particular, keratin hydrolysates proposed for sale as food supplements, as recipe ingredients for animal nutrition or as raw materials for animal feed are usually obtained by very partial hydrolysis. These hydrolysates usually have a high molecular weight due to the presence of a high level of "bound" amino acids forming peptides. Typically, the molecular weight of commercial compositions is at least 5000 Daltons. These keratin hydrolysates are relatively indigestible and contain little or no free amino acids. In fact, it is technically difficult and expensive from an industrial point of view to obtain keratin hydrolysates with very high levels of free amino acids. Moreover, if the hydrolysis is too extensive, there is a risk that the amino acids will be denatured and destroyed.

[0006] To obtain such hydrolysates, know-how based on the use and control of concentrated chemical entrants and processes belonging to the field of chemical engineering is required. Due to these high technical requirements, the majority of protein hydrolysates present on the market have a low proportion of free amino acids as a result of partial and incomplete hydrolysis.

[0007] However, as shown in the article "Extensive protein hydrolyzation is indispensable to prevent IgE-mediated poultry allergen recognition in dogs and cats," Olivry et al., BMC Veterinary Research (2017) 13:251, depending on the desired application, it may be advantageous or even necessary to have a composition with a very high free amino acid content.

[0008] JP 3-11099 describes a keratin hydrolysate obtained in two steps and its use in hair cosmetics: an acid and / or enzymatic hydrolysis step to obtain a hydrolysate with a cystine level of 5-18 mol% based on all amino acids and a molecular weight of 300-5000 Da, followed by a reduction step by electrolysis to obtain a hydrolysate with a cysteine ​​level of 5-18 mol% based on all amino acids and a molecular weight of 200-3000 Da. The hydrolysate according to the invention does not contain cysteine. Also, the cystine level is not very high.

[0009] Surprisingly and advantageously, the authors of the present invention have succeeded in overcoming the problems of the prior art and have obtained a keratin hydrolysate in which almost all amino acids are free amino acids.In particular, the amino acids that are the most difficult to obtain in free form during the hydrolysis process, such as valine, leucine, and isoleucine, are obtained in free form.Moreover, the free amino acids obtained by the present invention, especially valine, leucine, and isoleucine, are not damaged or denatured.

[0010] Other aspects, advantages and features of the present invention are set forth in the description and examples that follow.

[0011] The subject of the present invention is a keratin hydrolysate comprising at least 94% by weight, preferably at least 96% by weight and more preferably 100% by weight of free amino acids, relative to the total weight of amino acids in the hydrolysate, said hydrolysate comprising at least the following amino acids: at least 93% by weight, preferably at least 95% by weight of valine in free form, relative to the total weight of valine in the hydrolysate, at least 90% by weight, preferably at least 95% by weight of isoleucine in free form, relative to the total weight of isoleucine in the hydrolysate, and at least 95% by weight, preferably 100% by weight of leucine in free form, relative to the total weight of leucine in the hydrolysate.

[0012] Preferably, the hydrolysate according to the invention contains less than 2 mol % of cystine, preferably less than 1 mol %, more preferably less than 0.5 mol % of cystine, based on the total number of moles of amino acids in the hydrolysate. More preferably, the hydrolysate does not contain cystine.

[0013] According to one preferred embodiment, the keratin hydrolysate is a poultry keratin material hydrolysate.

[0014] A second subject of the invention relates to a method for preparing a hydrolysate according to the invention, in which the keratin material is a poultry keratin material, comprising at least the following steps, in this order: - subjecting the keratin material to at least one chemical hydrolysis with an acid under conditions suitable for obtaining a hydrolysate containing at least 88% by weight of free amino acids, relative to the total weight of the amino acids of the hydrolysate, the remainder of the amino acids of the hydrolysate being in the form of peptides having a molecular weight of less than or equal to 800 Daltons; - Extracting tyrosine and cystine from the hydrolysate, preferably using a base; - desalting the hydrolysate; - filtration, advantageously nanofiltration, by means of a membrane filter with a maximum aperture of 300 Da at a pressure of 15-40 bar and a flow rate of 300-900 l / h; - Drying step if necessary.

[0015] The present invention also relates to a composition comprising at least 94% by weight, preferably at least 96% by weight, more preferably 100% by weight, of free amino acids relative to the total weight of amino acids of the composition, said composition comprising at least the following amino acids: at least 93% by weight, preferably at least 95% by weight, of valine in free form relative to the total weight of valine in the composition; at least 90% by weight, preferably at least 95% by weight, of isoleucine in free form, relative to the total weight of isoleucine in the composition; at least 95% by weight, preferably 100% by weight, of leucine in free form, based on the total weight of leucine in the composition; at least 95% by weight, preferably 100% by weight, of threonine in free form, based on the total weight of threonine in the composition; at least 95% by weight, preferably 100% by weight, of serine in free form relative to the total weight of serine in the composition; at least 95% by weight, preferably 100% by weight, of glycine in free form, relative to the total weight of glycine in the composition; at least 95% by weight, preferably 100% by weight, of alanine in free form, relative to the total weight of alanine in the composition; at least 95% by weight, preferably 100% by weight, of phenylalanine in free form, relative to the total weight of phenylalanine in the composition; at least 95% by weight, preferably 100% by weight, of lysine in free form, based on the total weight of lysine in the composition; at least 95% by weight, preferably 100% by weight, of arginine in free form, relative to the total weight of arginine in the composition; At least 95% by weight, preferably 100% by weight, of proline in free form, relative to the total weight of proline in the composition.

[0016] The composition according to the invention can be obtained by mixing free amino acids.

[0017] The present invention also relates to a raw material for animal feed, the raw material containing 80 to 100% by weight of the hydrolysate according to the present invention or the composition according to the present invention based on the total weight of the raw material.

[0018] The present invention also relates to a complete feed for animal feeding, said complete feed comprising 5-40% by weight of the hydrolysate according to the present invention or the composition according to the present invention based on the total weight of said complete feed.

[0019] The composition according to the invention is advantageously a keratin hydrolysate, which has specific properties, in particular advantageous nutritional properties, high or even very high bioavailability, anallergic properties and palatability capacity for terrestrial and aquatic animal species.

[0020] One advantage of the composition according to the invention is its high digestibility. The composition according to the invention has an actual amino acid digestibility very close to the maximum possible (100%), measured according to the method described by Cozannet P., Primot Y., Gady C., Metayer JP, Lessire M., Skiba F., Noblet J. in "Standardised amino acid digestibility of wheat distillers' dried grains with solubles in force-fed cockerels" British Poultry Science, Feb. 2011; 52(1): 72-81. This high digestibility allows the composition according to the invention to be used in the food and food processing fields. The composition according to the invention is also water-soluble; specifically, 1 g of the composition according to the invention dissolves in 5 ml of water. This solubility confers advantageous properties for processing and the development of organoleptic properties in the final product, in particular high palatability. In particular, the very low cystine level in the hydrolysate makes it very water-soluble.

[0021] The hydrolysates according to the invention are distinguished by their high level of free amino acids: at least 94% by weight, preferably 96% by weight and advantageously 100% by weight, of the amino acids present in the hydrolysates according to the invention are in free form.

[0022] The hydrolysates according to the invention also include: at least 93% by weight, preferably at least 95% by weight, of valine in free form, relative to the total weight of valine in the hydrolysate; At least 90% by weight, preferably at least 95% by weight, of isoleucine in free form, based on the total weight of isoleucine in the hydrolysate; At least 95% by weight, preferably 100% by weight, of leucine in free form, based on the total weight of leucine in the hydrolysate.

[0023] Advantageously, the hydrolysate according to the invention is obtained from natural keratin material, in particular from poultry, advantageously from poultry feathers, such as hens, chickens, turkeys, ducks, geese, etc.

[0024] In particular, the hydrolysates according to the invention are not obtained from human keratin, such as hair.

[0025] Advantageously, the amino acid content of the hydrolysates according to the invention ranges from 40% to 90% by weight, preferably from 45% to 87% by weight, relative to the total weight of the hydrolysate, the hydrolysate also comprising mineral materials and water. As already mentioned, the amino acids of the hydrolysates according to the invention are essentially free amino acids.

[0026] The hydrolysate according to the invention comprises at least 94% by weight, preferably 96% by weight, advantageously 100% by weight, of free amino acids, based on the total weight of amino acids of the hydrolysate. The free amino acids are not denatured. Furthermore, the hydrolysate according to the invention has a high level of free branched amino acids, namely valine, leucine and isoleucine.

[0027] In fact, these branched amino acids are known to be more difficult to release under the same processing conditions.

[0028] Advantageously, the hydrolysate according to the invention comprises the following free amino acids: at least 95% by weight, preferably 100% by weight, of threonine in free form, based on the total weight of threonine in the hydrolysate; at least 95% by weight, preferably 100% by weight, of serine in free form, relative to the total weight of serine in the hydrolysate; at least 95% by weight, preferably 100% by weight, of glycine in free form, based on the total weight of glycine in the hydrolysate; at least 95% by weight, preferably 100% by weight, of alanine in free form, based on the total weight of alanine in the hydrolysate; at least 95% by weight, preferably 100% by weight, of phenylalanine in free form, based on the total weight of phenylalanine in the hydrolysate; at least 95% by weight, preferably 100% by weight, of lysine in free form, based on the total weight of lysine in the hydrolysate; at least 95% by weight, preferably 100% by weight, of arginine in free form, based on the total weight of arginine in the hydrolysate; At least 95% by weight, preferably 100% by weight, of proline in free form, based on the total weight of proline in the hydrolysate.

[0029] Advantageously, at least 94% by weight, preferably 96% by weight and advantageously 100% by weight, of the amino acids present in the hydrolysate have a molar mass of less than or equal to 250 Daltons, preferably at least 98% by weight of the amino acids present in the hydrolysate have a molar mass of less than or equal to 185 Daltons.

[0030] Preferably, the hydrolysate according to the invention comprises the following free amino acids, by weight relative to the total weight of amino acids of said hydrolysate: aspartic acid with a content in the range of 1.00-7.50% by weight, preferably in the range of 1.00-3.00% by weight, preferably 1.89% by weight; Threonine with a content ranging from 3.50 to 6.50% by weight, preferably ranging from 4.00 to 6.00% by weight, preferably 5.36% by weight; serine with a content in the range of 10.00-25.00% by weight, preferably in the range of 20.00-23.00% by weight, preferably 22.08% by weight; glutamic acid with a content in the range of 2.00-10.50% by weight, preferably in the range of 2.00-4.00% by weight, preferably 2.84% by weight; glycine with a content in the range of 6.00-25.00% by weight, preferably in the range of 20.00-23.00% by weight, preferably 22.08% by weight; alanine with a content in the range of 3.50-12.00% by weight, preferably in the range of 8.00-10.50% by weight, preferably 9.46% by weight; valine with a content ranging from 4.00 to 8.50% by weight, preferably ranging from 4.00 to 5.00% by weight, preferably 4.42% by weight; methionine with a content ranging from 0.10 to 2.00% by weight, preferably ranging from 0.20 to 1.00% by weight, preferably 0.32% by weight; isoleucine with a content ranging from 1.00 to 5.50% by weight, preferably ranging from 1.50 to 3.00% by weight, preferably 2.21% by weight; leucine with a content in the range of 4.50-8.50% by weight, preferably in the range of 5.00-6.00% by weight, preferably 5.36% by weight; tyrosine with a content in the range of 0.2-2.0% by weight, preferably in the range of 0.3-1.00% by weight, preferably 0.32% by weight; phenylalanine with a content in the range of 3.50-8.00% by weight, preferably in the range of 5.00-7.00% by weight, preferably 5.99% by weight; lysine with a content in the range of 0.30-3.00% by weight, preferably in the range of 0.50-1.50% by weight, preferably 0.63% by weight; histidine with a content in the range of 0.2-5.0% by weight, preferably in the range of 0.50-1.50% by weight, preferably 0.63% by weight; arginine with a content ranging from 2.50 to 6.50% by weight, preferably ranging from 3.00 to 4.00% by weight, preferably 3.79% by weight; Proline with a content in the range of 9.00-15.00% by weight, preferably in the range of 10.00-13.00% by weight, preferably 12.62% by weight.

[0031] The method for producing a keratin hydrolysate according to the invention comprises at least one chemical hydrolysis with an acid under conditions suitable for obtaining a hydrolysate which contains at least 88% by weight of free amino acids, based on the total weight of amino acids of the hydrolysate, the remainder of the amino acids of the hydrolysate being in the form of peptides having a molecular weight of less than or equal to 800 Daltons.

[0032] The chemical hydrolysis of keratin is carried out using an acid, preferably a strong acid selected from hydrochloric acid, phosphoric acid and sulfuric acid, preferably hydrochloric acid.

[0033] The acid concentration is preferably in the range of 14 to 34% by weight.

[0034] The weight ratio of the acid to the feathers is preferably in the range of 3-5.

[0035] The chemical hydrolysis is usually carried out at a temperature in the range of 110 to 115° C. for a period in the range of 1 to 24 hours, preferably in the range of 2 to 24 hours, and more preferably in the range of 6 to 20 hours.

[0036] According to one particular variant, the chemical hydrolysis is carried out in two steps: - a first chemical hydrolysis step carried out at a temperature ranging from 60 to 80°C for a period ranging from 4 to 5 hours, followed by - a second chemical hydrolysis step carried out at a temperature ranging from 100 to 115°C for a period ranging from 5 to 8 hours, The two hydrolysis steps can be carried out without an intermediate resting step or with an intermediate resting step of from 1 hour to 7 days.

[0037] More specifically, the first chemical hydrolysis is carried out at 72° C. for 4.5 hours and the second chemical hydrolysis is carried out at 107° C. for 6 hours, with an intermediate rest of 24 to 80 hours between the two chemical hydrolysis.

[0038] Advantageously, the hydrolysate obtained at the end of the chemical hydrolysis carried out in one or more steps contains less than 3.5% by mole of cystine relative to the total number of moles of amino acids of the hydrolysate.

[0039] The chemical hydrolysis is carried out in one or more steps, followed by at least one of the following steps, in this order: extracting cystine and tyrosine; desalination process, Filtration process.

[0040] The step of extracting cystine and tyrosine is carried out using a base, preferably a base selected from sodium hydroxide and potassium hydroxide, preferably sodium hydroxide. The step of extracting cystine and tyrosine is a conventional step, the performance of which is within the capabilities of a person skilled in the art.

[0041] The chemical hydrolysis step and the steps of extraction of cystine and tyrosine can optionally be followed by a step of purifying the resulting hydrolysate.

[0042] The desalting step is aimed at removing the sodium chloride or potassium chloride formed during the step of extracting tyrosine by adding sodium hydroxide or potassium hydroxide to hydrochloric acid. This desalting step is preferably carried out by electrodialysis, which is conventionally carried out by applying an electric current to a stack of alternating anionic and cationic membranes using pure water for the hydrolysate.

[0043] Preferably, the hydrolysate according to the invention contains less than 2 mol %, preferably less than 1 mol %, of tyrosine relative to the total number of moles of amino acids of the hydrolysate; more preferably the hydrolysate does not contain tyrosine.

[0044] Preferably, the hydrolysate according to the invention contains less than 2 mol %, preferably less than 1 mol %, even more preferably less than 0.5 mol % of cystine relative to the total number of moles of amino acids in the hydrolysate; more preferably the hydrolysate is free of cystine.

[0045] Advantageously, the hydrolysate according to the invention is free of tyrosine and cystine, the only traces of these amino acids being due to the limitations of the materials and operating conditions used during the extraction process, and is free of cysteine, unless the hydrolysate according to the invention is obtained after reduction by electrolysis.

[0046] Surprisingly and advantageously, the authors of the present invention have shown that by carrying out the filtration under the specific conditions of the present invention, high levels of free amino acids can be achieved without destruction or denaturation of said amino acids.

[0047] Advantageously, the filtration is carried out using a membrane filtration with a maximum aperture of 300 Da, preferably with a membrane filtration with a maximum aperture of 250 Da, and advantageously with a membrane aperture between 100 and 250 Da.

[0048] Advantageously, the filtration is carried out at a pressure between 15 and 40 bar.

[0049] Advantageously, the filtration is carried out at a flow rate ranging from 300 to 900 l / h, preferably ranging from 400 to 800 l / h.

[0050] According to a particularly preferred embodiment, the filtration is carried out using filtration membranes with a maximum aperture of 300 Da, preferably with a maximum aperture of 250 Da, and even more advantageously with a membrane aperture in the range of 100-250 Da, at a pressure between 15 and 40 bar and at a flow rate in the range of 300-900 l / h, preferably in the range of 400-800 l / h.

[0051] Advantageously, the filtration is nanofiltration.

[0052] Filtration or nanofiltration consists of circulating the desalted hydrolysate through a carefully calibrated membrane using a high pressure pump. The fraction that passes through is called the permeate and contains the free amino acids of interest, while the fraction that is retained is called the retentate and contains the peptides and remaining amino acids. The process is carried out using a tank equipped with a recirculation pump until a stable amino acid content in the permeate is obtained.

[0053] The process carried out according to the invention makes it possible to obtain a hydrolysate comprising at least 94% by weight, preferably at least 96% by weight and advantageously 100% by weight of free amino acids, based on the total weight of amino acids in the hydrolysate, including: at least 93% by weight, preferably at least 95% by weight of valine in free form, based on the total weight of valine in the hydrolysate; at least 90% by weight, preferably at least 95% by weight of isoleucine in free form, based on the total weight of isoleucine in the hydrolysate; at least 95% by weight, preferably 100% by weight of leucine in free form, based on the total weight of leucine in the hydrolysate.

[0054] Furthermore, the majority of the amino acids, in particular the following amino acids: threonine, serine, glycine, alanine, phenylalanine, lysine, arginine and proline, are in free form to the extent of at least 95% relative to the total weight of said amino acids in the hydrolysate.

[0055] As already mentioned, the present invention relates to the oral use of a composition, in particular a keratin hydrolysate, according to the invention or obtained according to the production process according to the invention, as a raw material for animal feed.

[0056] The present invention also relates to a composition, preferably a raw material comprising the hydrolysate according to the invention, and optionally further components, such as further free amino acids, in particular at least one amino acid selected from cystine, arginine, glutamic acid and aspartic acid.

[0057] Advantageously, as additional components, L-cystine or other amino acids such as arginine, glutamic acid and aspartic acid, which are partially retained by the membrane during nanofiltration, can be added.

[0058] The term "raw material" is intended to mean any product of natural, fresh or preserved plant or animal origin, resulting from their industrial transformation, as well as organic or inorganic substances, optionally including additives, which are intended to be used, as such or after transformation, for the preparation of complex animal feed or as carriers in premixes, to be fed orally to animals (Council Directive 96 / 25 / EC of 29 April 1996).

[0059] The raw material according to the invention is an amino acid mixture intended to be incorporated into a complete and balanced feed or to be used as a dietary supplement. It is therefore intended for oral administration to terrestrial and / or marine animals and / or humans. Said raw material does not belong to the therapeutic field.

[0060] The present invention relates more particularly to the use of the compositions, in particular the hydrolysates, in animal feed, more particularly as a raw material that is a source of free amino acids making it possible to dispense with dietary proteins of plant and / or animal origin having complex molecular structures and high molecular weights.

[0061] Preferably, the raw material for the animal feed also contains cystine.

[0062] Preferably, the raw material for animal feed contains, in addition to the amino acids of the hydrolysate, at least one additional amino acid selected from arginine, glutamic acid and aspartic acid.

[0063] Preferably, the raw material for animal feed according to the invention comprises, by weight relative to the total weight of amino acids of the composition, the following amino acids: aspartic acid with a content ranging from 6.00 to 8.00% by weight, preferably 6.89% by weight; Threonine with a content ranging from 3.50 to 5.50% by weight, preferably 4.50% by weight; serine with a content ranging from 17.00 to 19.00% by weight, preferably 17.91% by weight; glutamic acid with a content ranging from 9.00 to 11.00% by weight, preferably 9.84% by weight; glycine with a content ranging from 17.00 to 19.00% by weight, preferably 17.90% by weight; alanine with a content ranging from 7.00 to 9.00% by weight, preferably 7.95% by weight; valine with a content ranging from 3.00 to 5.00% by weight, preferably 3.71% by weight; cystine with a content ranging from 1.00 to 3.00% by weight, preferably 2.00% by weight; methionine with a content ranging from 0.10 to 1.00% by weight, preferably 0.25% by weight; isoleucine with a content ranging from 1.00 to 3.00% by weight, preferably 1.85% by weight; leucine with a content ranging from 3.50 to 5.50% by weight, preferably 4.53% by weight; tyrosine with a content ranging from 0.10 to 1.00% by weight, preferably 0.25% by weight; phenylalanine with a content ranging from 4.00 to 6.00% by weight, preferably 5.03% by weight; lysine with a content ranging from 0.30 to 1.00% by weight, preferably 0.50% by weight; histidine with a content ranging from 0.30 to 1.00% by weight, preferably 0.50% by weight; arginine with a content ranging from 5.00 to 7.00% by weight, preferably 5.79% by weight; Proline with a content in the range of 10.00-12.00% by weight, preferably 10.60% by weight.

[0064] Formulation of ingredients for animal feed according to the present invention employs conventional methods that are within the ordinary skill of those skilled in the art.

[0065] As already mentioned, the present invention also relates to a complete feed for animal feeding, which comprises 5 to 40% by weight of the composition, or preferably the hydrolysate, of the invention relative to the total weight of said complete feed.

[0066] This complete diet is highly hypoallergenic.

[0067] The complete feed for animal nutrition according to the invention may contain excipients typically used in compositions intended for oral administration, in particular humectants, thickeners, texturizing agents, flavorings, coating agents, preservatives, antioxidants, colorants, plant extracts, starches, plant fibers, minerals and non-protein ingredients such as vitamins.

[0068] Of course, the skilled artisan will be careful to select these excipients so as not to impair the properties of the complete feed for animal feeding.

[0069] The complete feed for animal feed according to the invention can be formulated in one of the following presentation forms: pellets, gel capsules, dragées, tablets, soft or hard capsules, or alternatively suspensions, solutions, gels, dry formulations containing less than 15% by weight water or wet formulations containing at least 50% by weight water and at most 85% by weight water.

[0070] The formulation of a complete feed for animal feeding according to the invention is carried out in a conventional manner that is within the ordinary capabilities of a person skilled in the art.

[0071] The present invention also relates to the use of the composition according to the invention or the hydrolysate according to the invention for producing a complete feed or raw material for animal feed.

[0072] The following examples are intended to illustrate the invention without limiting its scope.

[0073] example

[0074] Example 1 - Hydrolysate 1

[0075] Preparation of hydrolysate 1

[0076] 4500 kg of poultry feathers are placed in a 20000 liter reactor / hydrolyzer. The first chemical hydrolysis step is carried out by adding 18000 liters of hydrochloric acid (24%); hydrolysis is carried out at 72°C for 4.5 hours. The product obtained is stored at ambient temperature for 48 hours (intermediate rest). A second chemical hydrolysis is then carried out by heating at 107°C for 6 hours without the addition of acid. The product obtained is allowed to cool. Cystine and tyrosine are extracted by precipitation with sodium hydroxide at a pH of 4-5. The hydrolysate is desalted by electrodialysis. 22000 kg of liquid hydrolysate 1 are obtained.

[0077] Example 2 - Hydrolysate 2

[0078] Preparation of hydrolysate 2

[0079] 1 kg of desalted hydrolysate 1 is diluted with 19.2 kg of purified water and conveyed through a nanofiltration membrane calibrated at 100-250 Da at a flow rate of 400 l / h under a pressure of 20 bar. The weight of the retentate fraction collected is 5.2 kg and the permeate fraction is 14.55 kg. The influent desalted hydrolysate contains 93% free amino acids (i.e. 0.19 kg) and the effluent permeate fraction contains 99.06% free amino acids, i.e. 0.05 kg. The yield of free amino acids is therefore 26.4%.

[0080] Example 3 - Hydrolysate 3

[0081] Preparation of hydrolysate 3

[0082] 1 kg of desalted hydrolysate 1 is diluted with 12.6 kg of purified water and conveyed through a nanofiltration membrane calibrated at 100-250 Da at a flow rate of 800 l / h under a pressure of 36 bar. The weight of the retentate fraction collected is 5.2 kg and the permeate fraction is 8.55 kg. The influent desalted hydrolysate contains 93% free amino acids (i.e. 0.19 kg) and the effluent permeate fraction contains 97.87% free amino acids, i.e. 0.04 kg. The yield of free amino acids is therefore 22.4%.

[0083] result

[0084] Table 1 shows the free amino acid / total amino acid weight fraction for each amino acid present.

[0085] [Table 1]

[0086] *The percentage of free form amino acids in the hydrolysate is less than 0.002%.

[0087] Determination of the composition of hydrolysate 2

[0088] The amino acids of hydrolysate 2 are assayed according to a method conforming to EC Regulation 152 / 2009.

[0089] The amino acids are separated by chromatography on an ion exchange column (HPLC) and assayed by reaction with ninhydrin and photometric detection at 570 nm.

[0090] The free amino acid content relative to the total weight of amino acids is shown in Table 2 for each amino acid in hydrolysate 2.

[0091] [Table 2]

[0092] Example 4

[0093] -Raw materials for animal feed

[0094] From the composition of Table 2 to which L-cystine, glutamic acid, arginine and aspartic acid were added, raw materials for animal nutrition were prepared to obtain the following compositions shown in Table 3.

[0095] The amino acid content relative to the total weight of amino acids in the raw materials for animal feed is shown for each amino acid in Table 3.

[0096] [Table 3]

[0097] This composition is highly non-allergenic.

[0098] Additionally, preference for cats and dogs was observed.

Claims

1. Contains at least 94% by weight of free amino acids based on the total weight of amino acids in the hydrolysate; A keratin hydrolysate characterized in that it contains at least the following amino acids: at least 93% by weight of valine in free form, based on the total weight of valine in the hydrolysate; At least 90% by weight of isoleucine in free form, based on the total weight of isoleucine in the hydrolysate; and At least 95% by weight of leucine in free form, based on the total weight of leucine in the hydrolysate.

2. 2. The hydrolysate according to claim 1, characterized in that it contains at least one of the following free amino acids: at least 95% by weight of threonine in free form, based on the total weight of threonine in the hydrolysate; at least 95% by weight of serine in free form, based on the total weight of serine in the hydrolysate; at least 95% by weight of glycine in free form, based on the total weight of glycine in the hydrolysate; at least 95% by weight of alanine in free form, based on the total weight of alanine in the hydrolysate; at least 95% by weight of phenylalanine in free form, based on the total weight of phenylalanine in the hydrolysate; at least 95% by weight of lysine in free form, based on the total weight of lysine in the hydrolysate; At least 95% by weight of arginine in free form, based on the total weight of arginine in the hydrolysate; and At least 95% by weight of proline in free form, based on the total weight of proline in the hydrolysate.

3. 3. The hydrolysate according to claim 1, characterized in that it contains less than 2 mol% cystine relative to the total moles of amino acids in the hydrolysate.

4. Hydrolysate according to any one of claims 1 to 3, characterized in that it comprises at least one of the following amino acids, by weight relative to the total weight of amino acids of the hydrolysate: Aspartic acid content of 1.00 to 7.50% by weight; Threonine content of 3.50 to 6.50% by weight; Serine content of 10.00 to 25.00% by weight; Glutamic acid content of 2.00 to 10.50% by weight; glycine content of 6.00 to 25.00% by weight; alanine content of 3.50 to 12.00% by weight; valine content of 4.00 to 8.50% by weight; methionine content of 0.10 to 2.00% by weight; Isoleucine content of 1.00 to 5.50% by weight; A leucine content of 4.50 to 8.50% by weight; A tyrosine content of 0.2 to 2.0% by weight; phenylalanine content of 3.50 to 8.00% by weight; lysine content of 0.30 to 3.00% by weight; histidine content of 0.2 to 5.0% by weight; Arginine content of 2.50 to 6.50% by weight; and Proline content is 9.00 to 15.00% by weight.

5. A method for producing a hydrolysate according to any one of claims 1 to 4, characterized in that the keratin material is a poultry keratin material and that it comprises at least the following steps in this order: - subjecting the keratin material to at least one chemical hydrolysis with an acid under conditions to obtain a hydrolysate comprising at least 88% by weight of free amino acids relative to the total weight of amino acids of said hydrolysate, the remainder of the amino acids of said hydrolysate being in the form of peptides having a molecular weight of less than or equal to 800 Daltons; - Extracting tyrosine and cystine from the hydrolysate using a base; - desalting the hydrolysate; - filtration using a membrane filter with a maximum aperture of 300 Da at a pressure of 15-40 bar and a flow rate of 300-900 l / h; - drying, However, the chemical hydrolysis is carried out in two steps: a first chemical hydrolysis step carried out with 24% hydrochloric acid at a temperature of 72° C. for 4.5 hours, followed by - a second chemical hydrolysis step carried out without additional addition of acid at a temperature of 107°C for 6 hours; Between two chemical hydrolysis an intermediate rest step of 24 to 80 hours is carried out.

6. A method for producing a composition, comprising the step of adding the hydrolysate according to any one of claims 1 to 4.

7. A method for producing a raw material for animal feed, comprising producing a raw material containing 80 to 100% by weight of the hydrolysate according to any one of claims 1 to 4 relative to a total weight of the raw material.

8. 8. The method for producing raw materials for animal feed according to claim 7, characterized in that the raw materials further contain cystine.

9. The method for producing a raw material for animal feed according to claim 7 or 8, characterized in that the raw material contains at least one additional amino acid selected from arginine, glutamic acid and aspartic acid in addition to the amino acid of the hydrolysate according to any one of claims 1 to 4.

10. Method for producing a raw material for animal feed according to any one of claims 7 to 9, characterized in that the raw material comprises, by weight relative to the total weight of its amino acids, at least one of the following amino acids: Aspartic acid having a content of 6.00 to 8.00% by weight; Threonine content of 3.50 to 5.50% by weight; Serine content of 17.00 to 19.00% by weight; Glutamic acid having a content of 9.00 to 11.00% by weight; Glycine content of 17.00 to 19.00% by weight; alanine content of 7.00 to 9.00% by weight; valine content of 3.00 to 5.00% by weight; Cystine content is 1.00 to 3.00% by weight; methionine content of 0.10 to 1.00% by weight; Isoleucine content of 1.00 to 3.00% by weight; a leucine content of 3.50 to 5.50% by weight; A tyrosine content of 0.10 to 1.00% by weight; phenylalanine content of 4.00 to 6.00% by weight; lysine content of 0.30 to 1.00% by weight; histidine content of 0.30 to 1.00% by weight; Arginine content of 5.00 to 7.00% by weight; and Proline content is 10.00 to 12.00% by weight.

11. A method for producing a complete feed for animal feed, comprising producing a complete feed for animal feed containing 5 to 40% by weight of the hydrolysate according to any one of claims 1 to 4.

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