EP4146679A1

EP4146679A1 - Keratin hydrolysate high in free amino acids and high in free tyrosine, method for obtaining and using same for animal feed and plant nutrition

Info

Publication number: EP4146679A1
Application number: EP21722502.8A
Authority: EP
Inventors: Etienne Broin; Joel DUPERRAY; Jean-Philippe SOULARD; Renaud Sergheraert
Original assignee: Bretagne Chimie Fine SAS
Current assignee: Bretagne Chimie Fine SAS
Priority date: 2020-05-07
Filing date: 2021-05-05
Publication date: 2023-03-15
Also published as: KR20230006564A; CA3176533A1; WO2021224310A1; US20230192788A1; CN115515967A; JP2023525074A; FR3109938A1; FR3109938B1

Abstract

The invention relates to a keratin hydrolysate comprising at least 88%, preferably at least 90%, by weight of free amino acids relative to the total weight of the amino acids of the hydrolysate, and comprising a content of free tyrosine between 2% and 4%, preferably 2.5% to 3.5%, by weight relative to the total weight of the free amino acids of the hydrolysate, and a method for preparing said hydrolysate comprising, in particular, the following steps: acid hydrolysis, a pH adjustment and a desalination. The invention also relates to the use of said hydrolysate in particular for pet food, aquaculture food, and plant biostimulants.

Description

Title of the invention: Hydrolyzate of keratin with a high content of free amino acids and a high content of free tyrosine, process for obtaining and using it for animal feed and plant nutrition [0001] The present invention relates to the field of hydrolysates with high levels of free amino acids and for their uses in particular in the field of animal nutrition, in particular feline and canine food, in aquaculture and in agriculture, in particular as a plant biostimulant.

[0002] The amino acid-based compositions are used in very diverse fields such as nutraceuticals, cosmetics, plant, animal and human nutrition, for very different and specific applications in each of these fields. Mention may in particular be made of uses aimed at the growth and shine of hair in humans, as well as uses aimed at a supply of free amino acids constituting a source of specific proteins in animal feed, particularly in the fields of aquaculture and canine and feline nutrition.

[0003] One of the ways to obtain a composition based on amino acids is to produce a hydrolyzate of keratin materials.

[0004] Natural keratin materials predominantly comprise polypeptides of high molecular weight and with a highly crosslinked structure making it hardly accessible to enzymes. This natural keratin material is hardly digestible. However, it is known that the hydrolysis of keratin materials into amino acids improves their digestibility.

[0005] The keratin hydrolysates offered for sale in particular as food supplements, ingredients for formulating animal nutrition recipes, or raw materials for animal nutrition are generally obtained by very partial hydrolysis. These hydrolysates generally exhibit a high molecular mass due to the presence of high levels of so-called “linked” amino acids forming peptides and polypeptides. Typically the molecular weight of commercial compositions ranges from 5,000 to 50,000 daltons. These keratin hydrolysates are relatively poorly digestible and contain very little or no free amino acids. In fact, it is technically difficult and industrially expensive to obtain a keratin hydrolyzate having a very high level of free amino acids.

In addition, excessive hydrolysis presents a risk of denaturation and destruction of amino acids.

[0006] Patent application WO2019 / 043128 describes a keratin hydrolyzate with high levels of free amino acids, it is obtained by implementing a process in which the hydrolysis step is followed by an extraction step of tyrosine. This hydrolyzate has the advantages linked to the high levels of free amino acids, in particular a good digestibility, however this hydrolyzate does not include all the amino acids generally present at the end of an acid hydrolysis, in particular the levels of cysteine and tyrosine. are weak. However, obtaining a hydrolyzate which can be used in a complete and balanced food, without adding additional amino acids, is a property that is generally sought after.

[0007] Furthermore, the hydrolysates obtained by chemical hydrolysis in particular by acid hydrolysis are in salt form, while most uses, in particular in animal feed and in biostimulation, require desalted hydrolysates. However, desalination processes generally lead to a loss of a significant amount of certain amino acids, in particular the amino acids which precipitate at the end of neutralization, indeed desalination can generally only be carried out on a filtered solution. Consequently, the yields of hydrolysates obtained according to the methods of the prior art are not always satisfactory.

Surprisingly and advantageously, the inventors of the present invention have succeeded in overcoming the problems of the prior art by the implementation of a process making it possible to obtain a desalted keratin hydrolyzate, exhibiting a rate high in free amino acids and comprising all the amino acids generally present at the end of a acid hydrolysis. In addition, the profile of the amino acids of the hydrolyzate according to the present invention is close to that of the original keratin material.

Thus, the use of the hydrolyzate according to the present invention makes it possible to dispense with the great majority of the addition of additional amino acids, among those present in the original keratin material.

The free amino acids obtained according to the invention are not damaged or denatured, in particular the amino acids among the most difficult to release in free form during the hydrolysis process such as valine, leucine, isoleucine .

In addition, the method according to the present invention allows obtaining a good yield of amino acids, that is to say a good ratio between the total of total amino acids of the hydrolyzate according to the invention and the starting keratin material, because all the phases resulting from the various steps of the process are recovered and treated so as to extract the maximum therefrom, that is to say practically all the amino acids.

The present invention relates to a keratin hydrolyzate comprising at least 88%, preferably at least 90%, by weight of free amino acids relative to the total weight of amino acids of the hydrolyzate, said hydrolyzate comprising of free tyrosine in a content ranging from 2 to 4%, preferably 2.5 to 3.5% by weight relative to the total weight of the free amino acids of the hydrolyzate.

Advantageously, said hydrolyzate comprises at least 90%, preferably at least 93%, and preferably at least 95% of cystine in free form by weight relative to the total weight of cystine in the hydrolyzate.

[0013] According to a preferred embodiment, said hydrolyzate is desalted, that is to say it comprises less than 11%, preferably less 7% by weight of salts relative to the total weight of the hydrolyzate, the salts being chosen from sodium chloride, sodium sulfate, sodium phosphate, sodium chloride potassium, potassium sulfate and potassium phosphate, preferably sodium chloride.

[0014] A second object of the present invention is a process for preparing the keratin hydrolyzate according to the invention from an animal keratin material, preferably from poultry, comprising at least the following steps, in this order:

- subjecting the keratin material to at least one chemical hydrolysis by means of an acid under conditions capable of obtaining a hydrolyzate comprising at least 88% by weight of free amino acids relative to the total weight of amino acids of the hydrolyzate, the remainder of the amino acids of the hydrolyzate being in the form of peptides having a molecular mass of less than or equal to 800 Dalton;

- subjecting the hydrolyzate to a step of adjusting the pH to a value ranging from 3 to 5, preferably ranging from 4 to 5 and recovering the precipitate and the liquid phase;

- Separating the precipitate and the liquid phase, preferably by draining;

- subjecting the precipitate to at least one washing with water until a desalted precipitate comprising less than 1% of salts by weight relative to the total weight of the precipitate is obtained, and recovering the desalted precipitate on the one hand and the washing water on the other hand,

- combine the washing water and the liquid phase to obtain a solution and proceed to the desalination of this solution by electrodialysis to obtain a desalinated solution,

- add the desalted precipitate to said desalinated solution, - recover the desalinated suspension obtained.

[0015] According to a preferred variant, the suspension obtained is dried and the solid obtained at the end of the drying recovered.

The means for implementing the method according to the invention have the advantage of being simple: the invention can be implemented with a device using means commonly used in industry such as reactors, dryers, atomization towers. Several steps can be carried out in the same enclosure, moreover the meeting of the various phases is carried out easily without notable problems.

[0017] The present invention also relates to the use of keratin hydrolyzate in animal feed, in particular feline, canine, in aquaculture or in agriculture. The present invention relates more particularly to the use of the hydrolyzate according to the invention or prepared according to the invention as a component of a product chosen from foodstuffs for animal feed for companion animals, foodstuffs for pet animals. aquaculture, plant biostimulants.

Other aspects, advantages, properties of the invention will emerge clearly from the description, in particular from the examples, and from the drawings which follow, by way of indication and in no way limiting.

[0019] Detailed description

Advantageously, this hydrolyzate is obtained from natural keratin materials, animal, in particular poultry, advantageously from poultry feathers. Mention may be made, by way of poultry, of hens, in particular laying hens, chickens, turkeys, ducks, geese, etc. 'animals, animal nails. In particular, the hydrolyzate according to the present invention is not obtained from human keratin such as the hair.

As already mentioned, the hydrolyzate according to the present invention comprises at least 88%, preferably 90% by weight of free amino acids relative to the total weight of amino acids of the hydrolyzate. Advantageously, the total amino acid content of the hydrolyzate according to the invention ranges from 40% to 95%, preferably 45% to 93% by weight relative to the total weight of the hydrolyzate, the hydrolyzate comprising in addition to mineral matter and water. In addition, the hydrolyzate according to the invention has free branched amino acids: undenatured valine, leucine and isoleucine. However, these branched amino acids are known to be more difficult to release under identical operating conditions.

As already mentioned, the hydrolyzate according to the invention comprises at least 90%, preferably at least 93% and preferably at least 95% of cystine in free form by weight relative to the total weight of cystine in the hydrolyzate.

[0026] According to a preferred variant, the hydrolyzate according to the invention comprises: at least 95%, preferably 100%, of aspartic acid in free form by weight relative to the total weight of aspartic acid in the hydrolyzate; at least 95%, preferably 100%, of threonine in free form by weight relative to the total weight of threonine in the hydrolyzate; at least 95%, preferably 100%, serine in free form by weight relative to the total weight of serine in the hydrolyzate; at least 93%, preferably at least 95%, of glutamic acid in free form by weight relative to the total weight of glutamic acid in the hydrolyzate; at least 90%, preferably at least 93%, of glycine in free form by weight relative to the total weight of glycine in the hydrolyzate; at least 90%, preferably at least 93%, of alanine in free form by weight relative to the total weight of alanine in the hydrolyzate; at least 90%, preferably at least 93%, of phenylalanine in free form by weight relative to the total weight of phenylalanine in the hydrolyzate; at least 93%, preferably at least 95%, of proline in free form by weight relative to the total weight of proline in the hydrolyzate.

Furthermore at least 90% by weight of the amino acids of the hydrolyzate have a molecular mass less than or equal to 250 daltons, preferably less than or equal to 240 daltons. Consequently, this hydrolyzate can be used to prepare complete feeds for animal feed having hypoallergenic or even anallergic properties. The hydrolyzate obtained is advantageously desalted, that is to say it comprises less than 11%, preferably less than 7% by weight of salts relative to the total weight of the hydrolyzate, the salts being chosen from sodium chloride, sodium sulfate, sodium phosphate, potassium chloride, potassium sulfate and potassium phosphate, preferably sodium chloride (NaCl).

[0029] The determination of the percentage of salts falls within the competence of those skilled in the art. Preferably, the percentage of salts is determined by the dosage of the anions. In particular the chloride ions are determined by a potentiometric assay, by 0.1 N silver nitrate, followed by a combined Ag / AgCl electrode; the phosphate ions are determined by spectrophotometric determination of a phosphomolybdic complex according to the ISO 6878 standard and the sulphates by gravimetric determination by adding a barium salt according to the ISO 2480: 1972 standard.

The anions assay can be supplemented by a cation assay, in general the sodium and potassium assay is performed by flame ionization spectrophotometry according to the ISO 9964-2: 1993 standard.

The salt (s) content depends on the quality of the washing of the precipitate and the degree to which the electrodialysis is continued. It is within the competence of those skilled in the art to adjust the parameters of these steps, in particular to adapt the times, according to the desired salt content (s).

By "dry hydrolyzate" or "dried hydrolyzate" within the meaning of the present invention is meant a hydrolyzate containing less than 5% by weight of water. The water weight of the hydrolyzate is measured using an infrared thermobalance.

Preferably, the hydrolyzate according to the present invention comprises the following free amino acids, by weight, relative to the total weight of the free amino acids of the hydrolyzate: aspartic acid in a content ranging from 6.00 at 10.00%, preferably ranging from 7.00 to 9.00%, and preferably 7.83% by weight; threonine in a content ranging from 3.00 to 7.00%, preferably ranging from 4.00 to 6.00%, and preferably 4.93% by weight; serine in a content ranging from 11.00 to 15.00%, preferably ranging from 12.00 to 14.00%, and preferably 12.88% by weight; glutamic acid in a content ranging from 8.50 to 12.50%, preferably ranging from 9.50 to 11.50%, and preferably 10.47% by weight; glycine in a content ranging from 6.50 to 10.50%, preferably ranging from

7.50 to 9.50%, and preferably 8.56% by weight; alanine in a content ranging from 3.00 to 7.00%, preferably ranging from

4.00 to 6.00%, and more preferably 5.04% by weight; valine in a content ranging from 3.50 to 7.50%, preferably ranging from

4.50 to 6.50%, and preferably 5.61% by weight; cystine in a content ranging from 4.00 to 8.00%, preferably ranging from

5.00 to 7.00%, and more preferably 5.80% by weight; methionine in a content ranging from 0.10 to 2.00%, preferably ranging from 0.20 to 1.00%, and preferably 0.57% by weight; isoleucine in a content of 1.50 to 5.50%, preferably ranging from 2.50 to

4.50%, and preferably 3.50% by weight; leucine in a content ranging from 6.00 to 10.00%, preferably ranging from

7.00 to 9.00%, and more preferably 7.77% by weight; tyrosine in a content ranging from 2.50 to 3.50%, preferably 3.00 to

3.50% and preferably 3.15% by weight; phenylalanine in a content ranging from 3.00 to 7.00%, preferably ranging from 4.00 to 6.00%, and preferably 5.08% by weight; lysine in a content ranging from 0.50 to 3.00%, preferably ranging from

1.00 to 2.00%, and preferably 1.66% by weight; histidine in a content ranging from 0.10 to 2.00%, preferably ranging from

0.20 to 1.00%, and preferably 0.74% by weight; arginine in a content ranging from 4.00 to 8.00%, preferably ranging from

5.00 to 7.00%, and more preferably 5.82% by weight; proline in a content ranging from 8.50 to 12.50%, preferably ranging from 9.50 to 11.50%, and preferably 10.59% by weight.

Another advantage of the keratin hydrolyzate according to the present invention is that its amino acid profile is close to that of the original keratin material. In fact, with the exception of tryptophan destroyed in acid hydrolyses, the 17 amino acids present in the original keratin material are also present in free form in the final hydrolyzate.

Thus, the keratin hydrolyzate according to the present invention comprises 17 amino acids, and for each of the amino acids the percentage variation between the weight of the free amino acid in the hydrolyzate and the weight of this amino acid in the starting keratin material is less than 20% in absolute value, advantageously for 15 of these amino acids, said variation is less than 10% in absolute value.

The variation, in percentage, for an amino acid, corresponds to the ratio of the absolute value of the difference between the weight of the amino acid in the keratin material and the weight of the free amino acid in the hydrolyzate on the weight of the amino acid in the keratin material multiplied by 100, i.e. the following formula:

(| weight of amino acid in keratin material - weight of free amino acid in hydrolyzate | / weight of amino acid in keratin material) x 100.

Another advantage of the hydrolyzate according to the present invention is that it is very digestible, moreover, it is recognized to be of food grade. The hydrolyzate according to the invention has a true digestibility of its protein fraction of at least 98%. This value is very close to the maximum possible (100%).

The digestibility is measured in vivo according to the method described by ZM Larbier, AM Chagneau and M. Lessire in "Effect of protein intake on true digestibility of amino acids in rapeseed meals for adult roosters force fed with moistened feed". Animal Feed Science and Technology. 34 (1991) 255-260. [0039] Method

[0040] [Fig.1] is a diagram showing the main steps of the process according to the invention described below as well as the phases obtained at the end of these different steps. The stages are presented in rectangles and the phases in ellipses. According to the diagram in Figure 1, the process comprises hydrolysis followed by a pH adjustment step leading to a liquid phase and a precipitate which are subjected to a solid-liquid separation step. The precipitate is then subjected to washing to give the desalted precipitate (AA2). The liquid phase and the washing water are combined and this solution (AA1) is subjected to a desalination step leading to a desalinated solution. Then the desalted solution and the desalted precipitate (AA2) are combined and the suspension obtained is subjected to drying resulting in the obtaining of the dried desalinated hydrolyzate.

Acid hydrolysis The process for preparing the keratin hydrolyzate according to the invention implements at least one chemical hydrolysis by means of an acid under conditions capable of obtaining a hydrolyzate comprising at least 88% of weight of free amino acids relative to the total weight of amino acids in the hydrolyzate, the rest of the amino acids in the hydrolyzate being in the form of small peptides, i.e. having a molecular mass less than or equal to 800 Dalton.

[0043] The percentage of small peptides in the hydrolyzate according to the invention generally ranges from 5 to 12% by weight relative to the total weight of the hydrolyzate.

[0044] Indeed, the hydrolysis is not complete, the percentage of small peptides in the hydrolyzate is not zero, and it is 12% by weight at most.

The chemical hydrolysis of the keratin is carried out by means of an acid, preferably a strong acid chosen from hydrochloric, phosphoric and sulfuric acids, preferably hydrochloric acid. Preferably, the concentration of acid, preferably hydrochloric acid, ranges from 14 to 34% by weight. Preferably, the acid / keratin material weight ratio, in particular the acid / feather weight ratio, ranges from 2 to 5.

Chemical hydrolysis is generally carried out for a period ranging from 1 hour to 24 hours, preferably ranging from 6 to 20 hours at a temperature ranging from 100 to 115 ° C.

According to a particular variant, the chemical hydrolysis is carried out in two stages: a first chemical hydrolysis carried out at a temperature ranging from 60 to 80 ° C for a period ranging from 4 to 5 hours then a second chemical hydrolysis carried out at a temperature ranging from 100 to 115 ° C for a period ranging from 5 to 8 hours.

In addition, the two hydrolyses can be carried out without an intermediate pause step or by performing an intermediate pause step of between 1 hour and 7 days.

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, an intermediate break of 24 to 80 hours being carried out between the two hydrolyses chemical.

Advantageously, when a fatty part floats on the surface of the hydrolyzate, this supernatant is removed.

PH adjustment

Chemical hydrolysis, carried out in one or more steps, is followed by a pH adjustment step. The hydrolyzate is brought to a pH having a value ranging from 3 to 5, preferably from 4 to 5. This step is carried out by adding a base chosen from sodium hydroxide and potassium hydroxide, preferably 1. 'sodium hydroxide. This step is a classic step, the implementation of which falls within the competence of those skilled in the art.

This step also has the effect of precipitating, at least partially, the less soluble amino acids including cystine, tyrosine, leucine and isoleucine. These less soluble amino acids form the precipitate, the other amino acids remain in solution and form, with the salt formed and the water, the liquid phase.

Solid-liquid separation - Spinning

The pH adjustment step is followed by a step of separating the precipitate from the liquid phase. The separation step can be carried out by implementing any solid-liquid separation technique, in particular by the application of centrifugal force or of pressing, in particular by means of a filter press. According to a preferred variant, the separation step is a spinning, the spinning is advantageously carried out by applying a centrifugal force by means of a rotation of about 1000 rpm. This technique, known to those skilled in the art for performing a solid-liquid separation, consists in removing the liquid phase by the effect of centrifugal force, while maintaining the precipitate (solid fraction) on a cloth.

[0057] Washing

The precipitate, drained, recovered, preferably on the cloth of the wringer, is then washed with water until a desalted precipitate with a salt content of less than 1% by weight is obtained, by relative to the total weight of the precipitate. By “salts” is meant sodium chloride, sodium sulfate, sodium phosphate, potassium chloride, potassium sulfate and potassium phosphate, preferably sodium chloride (NaCl).

During washing, the water which passes over the precipitate in place on the wire entrains, by solubilization, the salts present in said precipitate as well as a few amino acids, while leaving the most insoluble amino acids in solid form.

At the end of the washing step, the water content of the precipitate ranges from 50 to 60% by weight relative to the total weight of the precipitate. The desalted precipitate mainly comprises the following amino acids: cystine, tyrosine and leucine, it also comprises valine, isoleucine and phenylalanine.

The possibility of performing the spinning and washing in the same chamber, in particular in the wringer, contributes to the simplification of the means for implementing the method according to the invention.

The washing water is collected and added to the liquid phase obtained at the end of the spinning, they form a salted solution of amino acids.

[0064] Desalination

The salted amino acid solution is subjected to a desalination step by electrodialysis. Said salty amino acid solution includes all amino acids, but cystine and tyrosine are present in very small amounts.

The desalination step aims to remove the salts, in particular the sodium chloride formed during the pH adjustment step by adding sodium hydroxide to the hydrochloric acid used in step d 'hydrolysis. This desalination step is carried out by electrodialysis. Electrodialysis is conventionally carried out by opposing pure water to the solution to be desalinated, the two solutions circulating separately and alternately between anionic and cationic membranes to which an electric current is applied. At the end of the desalination step, the salt content of the solution is less than 1% by weight of salt relative to the total weight of the solution.

[0067] Meeting of the phases

After the desalination step, the desalinated precipitate obtained at the end of the water washing step is introduced into the desalinated solution thus forming a suspension.

Surprisingly and advantageously, the inventors have shown that all the amino acids resulting from acid hydrolysis are present. In addition, the The profile of the amino acids of the hydrolyzate according to the present invention is close to that of the original keratin material.

Preferably, the suspension obtained is dried and the solid obtained after drying is recovered. The hydrolyzate according to the present invention is preferably in dry form, it comprises less than 5% by weight of water relative to the total weight of the hydrolyzate.

The hydrolyzate in dry form comprises less than 11%, preferably less than 7% by weight of salts relative to the total weight of the hydrolyzate.

The weight of total amino acids recovered in the hydrolyzate in dry form is at least equal to 80% of the weight of the total amino acids contained in the keratin material involved in the hydrolysis, preferably at least 84%.

[0073] Uses

As already mentioned, the present invention relates to the use of the hydrolyzate in animal nutrition, especially feline, canine, in aquaculture or in agriculture.

The present invention relates more particularly to the use of the hydrolyzate according to the invention or prepared according to the invention as a component of a product chosen from foodstuffs for animal feed for pets, foodstuffs. for aquaculture, plant biostimulants.

According to a first variant, the present invention relates to the use, orally, of the keratin hydrolyzate, according to the invention or obtained according to the preparation process according to the invention as a raw material for the animal feed.

[0077] The present invention also relates to a raw material comprising a hydrolyzate according to the present invention without additions of ingredients.

The term "raw material" means all products of plant or animal origin, in the natural state, fresh or preserved, and derived from their industrial transformation, as well as all organic or inorganic substances, including or not including additives, which are intended for use in feeding animals by the oral route, either directly as such, or after processing, for the preparation of compound feedingstuffs for animals, or as carriers of premixtures (Directive 96/25 / CE of the Council of April 29, 1996).

The raw material according to the present invention is a mixture of amino acids intended to be incorporated into a complete and balanced food in animals or to be used as a food supplement in humans. It is therefore intended for oral administration in terrestrial and / or marine animals and / or in humans. Said raw material does not belong to the therapeutic field.

The present invention relates more particularly to the use of the hydrolyzate, in animal feed and more particularly as a raw material source of free amino acids making it possible to dispense with food proteins of plant and / or animal origin. of complex molecular structure and large molecular weight.

The formulation of the raw material for animal feed according to the invention implements conventional processes which are part of the general skills of those skilled in the art.

As already mentioned, the present invention also relates to a complete feed for animal feed comprising from 0.25 to 40% by weight of the composition or preferably of the hydrolyzate according to the invention relative to the total weight of said complete food.

The complete feed for animal feed in accordance with the invention can be formulated with the excipients usually used in compositions intended for the oral route, in particular humectants, thickeners, texturing agents, flavor, coating agents, preservatives, antioxidants, colors, plant extracts, non-protein ingredients such as starches, plant fibers, minerals and vitamins. Of course, those skilled in the art will take care to choose these excipients so as not to alter the properties of the complete feed for animal feed.

The complete feed for animal feed in accordance with the invention can be formulated according to one of the following presentations: a kibble, a capsule, a dragee, a tablet, a soft or hard capsule, or even a suspension, a solution, a gel, a dry preparation containing less than 15% by weight of water, or a wet preparation comprising at least 50% by weight of water and 85% by weight of water at most.

[0086] The formulation of the complete feed for animal feed according to the invention uses conventional methods which are part of the general skills of those skilled in the art.

[0087] The invention also relates to the use of the composition according to the invention or of the hydrolyzate according to the invention to prepare a raw material or a complete feed for animal feed.

According to a second variant, the present invention is aimed at the use of keratin hydrolyzate as an ingredient promoting palatability in feed for aquaculture, in particular for rearing shrimp, in particular at the larval stage. and up to the magnification stage.

[0089] According to a third variant, the present invention relates to the use of keratin hydrolyzate as a plant biostimulant. The hydrolyzate according to the invention can be used on different parts of plants: seeds, leaves, flowers, fruits.

Biostimulants are defined as substances and / or microorganisms whose function, when applied to plants or to the rhizosphere, is to stimulate natural processes which promote / improve the absorption or use of nutrients , abiotic stress tolerance, crop quality or yield, regardless of the presence of nutrients. The hydrolyzate can also be used with an ingredient chosen from phytosanitary products, fertilizers, microorganisms, algae extracts, humic and fulvic acids, minerals.

The examples which follow aim to illustrate the invention without limiting its scope.

[0093] Examples

The amino acids presented in Tables 1 to 3 are assayed according to a method adapted from regulation EC 152/2009.

The amino acids are separated by chromatography (HPLC or "HPLC" in English) with an ion exchange column and assayed by reaction with ninhydrin and photometric detection at 570 nm.

Example 1- Hydrolyzate

Preparation of the hydrolyzate [0100] Hydrolysis [0100] In a 55,000 liter reactor / hydrolyzer, 9000 kg of poultry feathers containing 50% dry matter are introduced. Chemical hydrolysis is carried out by adding 18,000 liters of hydrochloric acid (23%), hydrolysis is carried out at 72 ° C for 4.5 hours. The product obtained is stored for 48 hours, allowing its temperature to rise naturally to room temperature. Then a second chemical hydrolysis is carried out by heating at 107 ° C for 6 hours without adding acid. The hydrolyzate obtained comprises 88% by weight of free amino acids, the remainder of the amino acids of the hydrolyzate being in the form of small peptides with a molecular mass of less than or equal to 800 Dalton. [0100] Purification

The hydrolyzate is then allowed to settle in order to remove the fat provided by the keratin material which floats on the surface of the aqueous phase. The hydrochloric acid introduced in excess in the hydrolysis step. 8000 kg of concentrate are recovered. Then 4,500 kg of water are added to it to obtain 12,500 kg of dilute concentrate.

[0102] pH adjustment

30.5% sodium hydroxide is added to the hydrolyzate, to bring the pH to a value between 4 and 5. When adding sodium hydroxide, the least soluble amino acids, in particular cystine, tyrosine, leucine , isoleucine precipitate at least partially. The other amino acids remain completely in solution in the liquid phase.

[0104] Spin

The suspension is then placed in a wringer, to separate the precipitate (which remains on the cloth), and to recover the liquid phase, corresponding to 17000 kg, in a tank.

[0106] Washing

[0107] The precipitate remaining on the cloth is then washed by introducing 3000 kg of water directly into the wringer to remove the salt (NaCl). The washing water, corresponding to 3440 kg, is sent to the tank which already contains the liquid phase resulting from the dewatering, to give 20 440 kg of a solution called AA1. The 1560 kg of washed precipitate are recovered, which corresponds to the product AA2.

The composition of free amino acids of the AA1 solution is presented in Table 1.

[0109] [Table 1]

[0110] AA1 has a dry matter content of 34.07%, by measurement by means of an infrared thermobalance, a NaCl content of 14.74% and a free amino acid content of 93.4% by weight per relative to the total weight of total amino acids of AA1.

The 1560 kg of washed precipitate, containing less than 1% of NaCl are recovered. The dry matter content is 44% by weight by measurement by means of an infrared thermobalance. The free amino acid composition of the washed, dried precipitate is shown in Table 2. [0112] [Table 2]

The AA2 precipitate has a free amino acid content of 92.17% by weight relative to the total weight of the total amino acids of the AA2 precipitate.

[0114] Desalination

[0115] The AA1 solution (liquid phase resulting from the dewatering and the water for washing the precipitate together) weighing 20,440 kg is desalinated by electrodialysis in front of water, to give approximately 14,300 kg of desalinated solution, containing less than 1 % NaCl. The electrodialyzer used to perform the desalination consists of a double stack of 2 x 600 alternating anionic and cationic membranes, between which the solutions circulate, and through which a direct electric current flows.

[0116] Meeting of the phases The washed precipitate corresponding to 1560 kg and the desalinated solution corresponding to 14300 kg are combined to give 15,860 kg of suspension, which is spray-dried in a drying tower, the inlet temperature of which is 172 ° C and at the outlet. of 80 ° C and equipped with a sieve of 2500pm. About 3860 kg of powder are obtained, the composition of which is given in Table 3.

[0118] Table 3 shows, in the second column: the weight fraction of each AAL (free amino acids) of the hydrolyzate relative to the total of the AALs; in the third column: the weight fraction in each AA (amino acids) of the original keratin material relative to the total of the AAs; in the fourth column, the percentage change, in absolute value, between the weight of the free amino acid in the hydrolyzate and the weight of this amino acid in the keratin material.

[0119] [Table 3]

The hydrolyzate obtained has a solids content of 98.6%, a NaCl content of 4.7% and a free amino acid content of 91.11% by weight relative to the total weight of amino acids. total hydrolyzate.

[0121] The starting keratin material contains 93% of total amino acids on the dry matter (4500 kg of dry matter), and the hydrolyzate obtained (3860 kg as it is) contains 90.6% of total amino acids on the dry matter. as it is, the yield of total amino acids is 83.6%.

In addition, the profile of the amino acids of the hydrolyzate according to the present invention is close to that of the original keratin material, in fact as presented in the fourth column, for each of the 17 amino acids, the variation in percentage between the weight of the free amino acid in the hydrolyzate and the weight of this amino acid in the starting keratin material is less than 20% in absolute value, moreover for 15 of them, this weight variation is less at 10%. [0123] Example 2- Digestibility The true digestibility of the proteins of the hydrolyzate according to the invention is very high since it is equal to 98.99% and therefore very close to the possible maximum (100%). This value was obtained according to the following protocol on cecectomized roosters, which is a reference model for measuring the bioavailability of proteins in the animal kingdom.

[0125] Experimental protocol

[0126] The digestibility measurements are carried out on cecectomized adult roosters housed in individual cages and fed outside the test period with a standard diet.

[0127] 2 repetitions of 4 caecectomized roosters are used. All the animals are fasted for 24 hours before ingesting a single meal of 80 g composed of 24 g of sample (hydrolyzate) mixed with 56 g of sugar.

[0128] All the faeces (= faeces), including endogenous losses, are collected during the following 48 hours in two periods of 24 hours to prevent their fermentation and possible deterioration.

These faeces, excluded from any contamination such as feathers for example, are carefully taken before being frozen (-80 ° C).

The faeces are then lyophilized in the oven, combined and mixed into 2 pools corresponding to the 2 repetitions of 4 animals used for each of the 2 hydrolysates. The 2 pools are analyzed.

[0131] Nutritional analyzes (dry matter, crude proteins (Dumas method ISO 16634-1: 2008 standard) are carried out on the hydrolyzate, the feces of roosters as well as on the endogenous losses. These data are used to calculate the true digestibility. proteins.

For this true protein digestibility value, due to the contamination of bird droppings by uric nitrogen, protein nitrogen is measured in the faeces (Terpstra method; Terpstra KD and N. De Hart. 1973. . "The estimation of urinary nitrogen and faecal nitrogen in poultry excreta »Zeitschrift für Tierphysiologie Tierernàhrung und Futtermittelkunde. 32 (1-5): 306-320).

[0133] The true digestibility of proteins measured as a percentage is therefore calculated according to a quantitative method by the difference between the quantity of hydrolyzate ingested and the quantity of faeces excreted, corrected for endogenous losses according to the following formula.

[0134] True protein digestibility% = (Proteins ingested hydrolyzate - (proteins excreted faeces- endogenous excreted proteins)) / Proteins ingested hydrolyzate x100.

[0135] The hydrolyzate according to the invention is therefore very easily assimilated by the body.

[0136] Example 3- Raw material for animal feed

A raw material for animal nutrition is prepared from the hydrolyzate, the composition of which in free amino acids is presented in Table 3 (2nd column) without the addition of additional amino acids, in particular without the addition of L-tyrosine. , precursor of melanin, pigment responsible for the dark colorings (brown and black) of the coat and without addition of L-Cystine, essential for good skin health and constituting the keratin of animal coats.

The raw material prepared is hypoallergenic.

[0139] In addition, its power of palatability on cats and dogs has been observed.

Claims

[Claim 1] [Keratin hydrolyzate characterized in that it comprises at least 88%, preferably at least 90%, by weight of free amino acids relative to the total weight of amino acids of the hydrolyzate, said hydrolyzate comprising free tyrosine in a content ranging from 2 to 4%, preferably 2.5 to 3.5% by weight relative to the total weight of the free amino acids of the hydrolyzate.

[Claim 2] Hydrolyzate of keratin according to claim 1 characterized in that it comprises at least 90%, preferably at least 93% and preferably at least 95% of cystine in free form by weight relative to the total weight of cystine in the hydrolyzate.

[Claim 3] Hydrolyzate of keratin according to claim 1 or 2 characterized in that it is desalted, that is to say that it comprises less than 11%, preferably less 7% by weight of salts relative to the weight total hydrolyzate, the salts being chosen from sodium chloride, sodium sulfate, sodium phosphate, potassium chloride, potassium sulfate and potassium phosphate, preferably sodium chloride.

[Claim 4] Hydrolyzate of keratin according to any one of claims 1 to 3, characterized in that it comprises the following free amino acids: at least 95%, preferably 100%, of aspartic acid in free form by weight per relative to the total weight of aspartic acid in the hydrolyzate; at least 95%, preferably 100%, of threonine in free form by weight relative to the total weight of threonine in the hydrolyzate; at least 95%, preferably 100%, of serine in free form by weight relative to the total weight of serine in the hydrolyzate; at least 93%, preferably at least 95%, of glutamic acid in free form by weight relative to the total weight of glutamic acid in the hydrolyzate; at least 90%, preferably at least 93%, of glycine in free form by weight relative to the total weight of glycine in the hydrolyzate; at least 90%, preferably at least 93%, of alanine in free form by weight relative to the total weight of alanine in the hydrolyzate; at least 90%, preferably at least 93%, of phenylalanine in free form by weight relative to the total weight of phenylalanine in the hydrolyzate; at least 93%, preferably at least 95%, of proline in free form by weight relative to the total weight of proline in the hydrolyzate.

[Claim 5] Hydrolyzate of keratin according to any one of claims 1 to 4 obtained from a keratin material comprising 17 amino acids, in which, for each of the amino acids, the percentage change between the weight of the acid free amino in the hydrolyzate and the weight of this amino acid in the starting keratin material is less than 20% in absolute value, advantageously for 15 of these amino acids, said variation is less than 10% in absolute value.

[Claim 6] A hydrolyzate according to any one of claims 1 to

5 characterized in that it comprises the following free amino acids, by weight, relative to the total weight of free amino acids of the hydrolyzate: aspartic acid in a content ranging from 6.00 to 10.00%, preferably ranging from 7.00 to 9.00%, and more preferably 7.83% by weight; threonine in a content ranging from 3.00 to 7.00%, preferably ranging from

4.00 to 6.00%, and more preferably 4.93% by weight; serine in a content ranging from 11.00 to 15.00%, preferably ranging from

12.00 to 14.00%, and more preferably 12.88% by weight; glutamic acid in a content ranging from 8.50 to 12.50%, preferably ranging from 9.50 to 11.50%, and more preferably 10.47% by weight; glycine in a content ranging from 6.50 to 10.50%, preferably ranging from

7.50 to 9.50%, and preferably 8.56% by weight; alanine in a content ranging from 3.00 to 7.00%, preferably ranging from 4.00 to 6.00%, and more preferably 5.04% by weight; valine in a content ranging from 3.50 to 7.50%, preferably ranging from 4.50 to 6.50%, and preferably 5.61% by weight; cystine in a content ranging from 4.00 to 8.00%, preferably ranging from

5.00 to 7.00%, and more preferably 5.80% by weight; methionine in a content ranging from 0.10 to 2.00%, preferably ranging from

0.20 to 1.00%, and preferably 0.57% by weight; isoleucine in a content of 1.50 to 5.50%, preferably ranging from 2.50 to

3.50% and preferably 3.15% by weight; phenylalanine in a content ranging from 3.00 to 7.00%, preferably ranging from 4.00 to 6.00%, and preferably 5.08% by weight; lysine in a content ranging from 0.50 to 3.00%, preferably ranging from 1.00 to 2.00%, and preferably 1.66% by weight; histidine in a content ranging from 0.10 to 2.00%, preferably ranging from

5.00 to 7.00%, and more preferably 5.82% by weight; proline in a content ranging from 8.50 to 12.50%, preferably ranging from

9.50 to 11.50%, and preferably 10.59% by weight.

[Claim 7] Process for preparing the hydrolyzate according to any one of claims 1 to 6, from an animal keratin material, preferably from poultry, characterized in that it comprises at least the following steps, in this order :

- Separating the precipitate and the liquid phase, preferably by draining;

- add the desalted precipitate to said desalinated solution,

-recover the desalted suspension obtained.

[Claim 8] Process for preparing the hydrolyzate according to the preceding claim, in which the chemical hydrolysis is carried out for a period ranging from 1 hour to 24 hours, preferably ranging from 6 to 20 hours at a temperature ranging from 100 to 115 ° C.

[Claim 9] Process for preparing the hydrolyzate according to one of claims 7 or 8, in which the chemical hydrolysis is carried out in two stages:

-a first chemical hydrolysis carried out at a temperature ranging from 60 to 80 ° C for a period ranging from 4 to 5 hours then

a second chemical hydrolysis carried out at a temperature ranging from 100 to 115 ° C. for a period ranging from 5 to 8 hours.

[Claim 10] A process for preparing the hydrolyzate according to one of claims 7 to 9, in which the suspension obtained is dried and the solid obtained after drying is recovered.

[Claim 11] Use of the hydrolyzate according to one of claims 1 to 6 or obtained according to the process according to one of claims 7 to 10 as a component of a product chosen from foodstuffs for animal feed of pets, food for aquaculture, plant biostimulants.