GB2061956A - Process for the preparation of keratin hydrolysates - Google Patents

Abstract

Oligopeptide compositions are obtained by hydrolysis of a keratin material wherein the material is subjected to a sensitising treatment carried out with an electrolyte in an aqueous medium at a concentration of at least 8 mols per litre, or with a polar solvent, or where the keratin material is in the form of keratin with a cuticle, with at least one cuticle-removing agent which is ultrasound or formic acid at a concentration of at least 90% by weight, as cuticle-removing agent.

Description

SPECIFICATION Process for the preparation of keratin hydrolysates This invention relates to a process for the preparation of an oligopeptide composition from a keratin material which is subjected to enzymatic hydrolysis.

It is known that keratin hydrolysates, and in particular hydrolysates containing a major proportion of oligopeptides, are of great value in the cosmetic industry for their action on the surface condition of the hair or on the skin, and in the food industry. However, the value of these compositions essentially depends on their oligopeptide content; thus the protein material, consisting of the keratin used as the raw material, must be fractionated into oligopeptide chains containing several aminoacids but have a sufficiently low molecular weight to be water-soluble. The value of keratin hydrolysates is thus the greater, the lower the free aminoacid content of these hydrolysates.Furthermore, it has been found that it is very advantageous to retain, in the oligopeptide compositions, the cystine linkages existing in the keratin, the cystine producing more energy in the form of oligopeptides than in the form of an aminoacid.

It has been proposed to prepare keratin hydrolysates either from undegraded keratin raw materials, for example hog bristles, poultry feathers or horn, or from fibrous waste products and keratin waste, for example the by-products of pork butchery and the tanning trade. These keratins orkeratin derivatives are subjected either to partial alkaline or acid chemical hydrolysis in order to limit the production of free aminoacids, orto enzymatic hydrolysis.

It is known that the customary proteolytic enzymes (pepsin, trypsin, chymotrypsin and papain) have no substantial action on undegraded natural keratins, that is to say keratins which have not undergone any chemical, industrial or cosmetic treatment. Even the enzymes described as possible keratonilytics, such as the enzymes extracted from the various strains of "keratomyces" (pronase, keratinase, M'zyme and PSF 2019), in fact have very reduced, if not zero, actions on the main natural keratin materials; for example, the efficiency with which human hair subjected to these enzymes is digested is less than 10%.Certainly, industrial keratin waste and by-products can be digested by proteolytic or keratolytic enzymes, but in this case, digestion arises from: the fact that the starting keratin material is degraded and most of the cystine linkages in the keratin have disappeared; as a result, the hydrolysates obtained contain virtually no cystine.

In fact, all the enzymatic hydrolyses having a considerable degree of efficiency are hydrolyses which are either applied to a raw material in which the cystine linkges have already largely disappeared, or are applied to a material which has been subjected to a pretreatment, the purpose of which is to cause the majority of the cystine linkages to disappear. In all the other cases, the enzymatic action of the keratin has virtually zero efficiency.

It has also been proposed to carry out acid or alkaline chemical hydrolyses in order to obtain keratin hydrolysates. Acid hydrolyses are difficult to control and the hydrolysates obtained are rich in free aminoacids, even when the acid solutions are of low concentration; the yield of oligopeptides is therefore low. Alkaline hydrolyses are carried out in the presence of alkali metal hydroxides or quaternary ammonium hydroxides and result in the destruction of certain aminoacids and in particular of the cystine; H2S, lanthionine, lysinoalanine and cysteine are formed. The hydrolysates thus obtained are therefore still very low in cystine.

Accordingly there is no known method for the preparation of keratin hydrolysates which makes it possible to obtain oligopeptides containing a significant concentration of cystine. Either the hydrolysates have a low yield of oligopeptides and contain a large number of free aminoacids, or the hydrolysates virtually no longer contain cystine.

The object of the present invention is to provide a process for the preparation of an oligopeptide composition containing a high concentration of cystine, this process comprising enzymatic hydrolysis of the keratin after the latter has been subjected to a pretreatment which does not destroy the cystine. Effectively all known pretreatments of keratin materials in order to permit enzymatic action are pretreatments which destroy cystine.In this respect, there may be mentioned the oxidation processes, which irreversibly convert the cystine to cysteic acid, the processes involving sulphite treatment, which partially reduce the cystine to cysteine with the formation of an equivalent amount of S-sulphocysteine, and the processes involving sulphite treatment, which partially reduce the cystine to cysteine with the formation of an equivalent amount of S-sulphocysteine, and the processes involving reduction with thiols, which convert the cystine to cysteine, but also to lanthionine (with sulphur loss) and mixed disulphide. In all cases, the enzymatic hydrolysates obtained are of course low in cystine because the highly efficient action of the enzymes has been considered to be essentially incompatible with the presence iof cystine linkages in the material to be hydrolysed.

According to the present invention, it has been discovered, surprisingly, that it is possible to achieve a highiy efficient enzymatic hydrolysis action without substantially destroying the cystine linkages initially present in the keratin material subjected to hydrolysis, provided that the material to be hydrolysed is subjected beforehand to a sensitising action carried out either with hydrogen bond acceptors consisting of concentrated solutions of electrolytes, or with polar solvents which dissolve the interfibrillar bonding agents existing between the bundles of fibrils, consisting of microfibrils which are themselves formed of the protein chains of the keratin, or also, in the case where the keratin material contains a cuticle enveloping the actual keratin product, with a cuticle-removing agent.

In all cases, the sensitising treatment has no significant action on the cystine linkages of the keratin, with the result that the hydrolysates obtained contain more than 30% of the cystine linkages existing in the starting keratin material. By way of comparison, in analogous prior art compositions, which are rich in oligopeptides, it is never possible to find more than 10% of the cystine linkages of the starting keratin material.

The present invention thus provides a process for the preparation of an oligopeptide composition by the hydrolysis of a keratin material, this process comprising a treatment with proteolytic and/or keratolytic enzymes, characterised in that, before the enzymatic treatment, the keratin material is subjected to a sensitising treatment carried out by means of at least one sensitising agent which is an electrolyte acting in an aqueous medium at a concentration which is greater than or equal to 8 mols per litre, or a polar solvent, or in addition, in the case where the keratin material consists of keratin with a cuticle, by means of at least one cuticle-removing agent which is ultrasound or formic acid at a concentration above 90% by weight in the treatment medium.

Amongst the electrolytes which can particularly be used in the process according to the invention, it is appropriate to mention lithium bromide.

If the sensitising agent consists of one or more polar solvents, these polar solvents preferably constitute at least 75% by weight of the medium in which the sensitising treatment is carried out. Amongs the solvents which can particularly be used, it is appropriate to mention dimethylformamide and methanol.

If the sensitising treatment is carried out by means of at least one electrolyte and/or at least one polar solvent, the said treatment is preferably carried out for a period of time of at least 30 minutes and at a temperature from ambient temperature to the reflux temperature of the medium at atmospheric pressure.

If formic acid is used as the cuticle-removing agent in the treatment of keratin with a cuticie, e.g. natural hair, the sensitisation is preferably carried out for a period of time of at least 30 minutes and at a temperature from ambient temperature to the reflux temperature at atmospheric pressure.

If the cuticle-removing agent is an ultrasonic emission, it has been found that satisfactory results can be obtained if the ultrasound has a frequency of 20 KHz to 70KHz and a period of action of at least 30 minutes, the dissipated power being 50 to 150 watts per dm3 treated.

If the keratin material used as the raw material has been subjected to the abovementioned sensitising treatment, it is possible to carry out enzymatic hydrolysis using proteolytic and/or keratolytic enzymes and to obtain very satisfactory hyrolysis efficiencies. The enzymatic treatment is advantageously carried out at a pH which is less than or equal to 9 and at a temperature below 50"C in order to prevent disturbing alkalin hydrolysis from taking place, so that the enzymes are not necessarily at the pH corresponding to their optimum kinetics. The concentration of enzymes used depends on the operating conditions and should be sufficient to achieve an enzymatic action in the medium. The enzymatic treatment generally lasts from 20 hours to 90 hours.

The hydrolysate obtained can either be used in the form of a solution, after adjustment of the pH, of lyophilised, or dialysed, or atomised without raising the temperature, or recovered in the form of a dry residue in a rotaryevaporatorto say 40"C, provided that the medium has been neutralised, or precipitated in a solvent medium. In all cases, it is found that the oligopeptide composition obtained contains only a small amount of free aminoacids, is rich in oligopeptides having a molecular weight of 1,000 to 5,000, and contains more than 30% of the cystine linkages present in the starting keratin material.

The present invention also provides an oligopeptide composition obtained by the process defined above, which composition is characterised in that more than 75% by weight of the oligopeptides present therein have a molecular weight of 1,000 to 5,000, the composition moreover containing more than 30% by weight of the cystine groups present in the keraton material used as the raw material.

The oligopeptide composition obtained can be used, in particular, for the treatment of the hair or skind or in the food industry.

The following Examples further illustrate the present invention.

In these Examples, the enzymatic digestion efficiency is calculated by the analysis (chromatography of an ion exchange resin), after hydrolysis, of an aliquot of the filtered and centrifuged supernatant. In each Example, the enzymatic digestion efficiencies for the treated keratin material, with or without prior sensitisation, were compared. Furthermore, the cystine content initially present in the treated natural keratin and the cystine content of the hydrolys obtained were compared (protein analysis).

Example 1: a) First step: Sensitisation 100 g of cut hair (2 cm lengths) are immersed in two litres of dimethylformamide, preheated to 1 200C.

The solution is left for two hours at 1200C.

The hair is then filtered off; it is rinsed several times with demineralised water and then with alcohol and ethers It is dried at ambient temperature.

b) Second step: Enzymatic digestion An enzymatic solution containing the proteinase "PSF 2019" (Société ORIL - PARIS) is prepared just before use. Its formula is as follows: Purified proteinase "PSF 2019" (11,000 Anson units/mg) 3.2 g Boric acid 22.5 g Normal sodium hydroxide solution 130 ml MgCl2.6H20 0.03 g Demineralised water q.s.p. 2,000.00 ml The hair presensitised with dimethylformamide is immersed in the enzymatic solution, heated to 40"C. A blade stirrer provides continuous stirring.

The digestion last four days. After the insoluble residue has been filtered off, the solution is neutralised.

The results obtained are as follows: 1) enzymatic digestion efficiency: unsensitised control hair : 5% sensitised hair : 38% 2) characterisation of the keratin hydrolysate: cystine content of the hydrolysate: 56 x 10-3 mols per 100 g of total protein material cystine content of the initial keratin: 62 x 10-3 mols per 100 g of total protein material Example 2: a) First step: Sensitisation An identical procedure to that of Example 1 is used, but the sensitisation is continued for four hours.

b) Second step: Enzymatic digestion An identical procedure to that of Example 1 is used.

The results obtained are as follows: 1) enzymatic digestion efficiency: unsensitised control hair : 5% sensitised hair : 95% 2) characterisation ofthe keratin hydrolysate: cystine content of the hydrolysate: 50 x 10-3 mols per 100 g of total protein material cystine content of the initial keratin: 62 x 10-3 mols per 100 g of total protein material Example 3: a) Ffrststep : Sensitisation An identical procedure to that of Example 1 is used, but the sensitisation is continued for six hours.

b) Second step: Enzymatic digestion An identical procedure to that of Example 1 is used.

The results obtained are as follows: 1) enzymatic digestion efficiency: unsensitised control hair : 5% sensitised hair : 98% 2) characterisation ofthe keratin hydrolysate: cystine content of the hydrolysate: 35 x 10.2 mols per 1009 of total protein material cystine content of the initial keratin: 62 x 10-3 mols per 100 g of total protein material Example 4: a) Ffrststep : Sensftisation 100 g of cut hair (2 cm lengths) are immersed in two litres of dimethylformamide, preheated to 1400C.

The solution is heated to the boil and reflux is maintained for one hour.

The hair is filtered off; it is rinsed several times with demineralised water and then with alcohol and ether.

It is dried at ambient temperature.

b) Second step: Enzymatic digestion An identical procedure to that of Example 1 is used.

The results obtained are as follows: 1) enzymatic digestion efficiency: unsensitised control hair : 5% sensitised hair : 81% 2) characterisation of the keratin hydrolysate: cystine content of the hydrolysate: 25 x 10.2 mols per 100 g of total protein material cystine content of the initial keratin: 62 x 10-3 mols per 100 g of total protein material Example 5: a) Firststep: Sensitisation 100 g of cut hair (2 cm lengths) are immersed in two litres of a solution consisting of 1,500 ml of dimethylformamide and 500 ml of demineralised water.

This solution is heated to the boil and reflux is maintained for three hours.

The hair is filtered off; it is rinsed several times with demineralised water and then with alcohol and ether.

It is dried at ambient temperature.

b) Second step : enzymatic digestion An identical procedure to that of Example 1 is used.

The results obtained are as follows: 1) enzymatic digestion efficiency: unsensitised control hair : 5% sensitised hair : 59% 2) characterisation of the keratin hydrolysate: cystine content of the hydrolysate: 42 x 10-3 mols per 100 g of total protein material cystine content of the initial keratin: 62 x 10-3 mols per 100 g of total protein material Example 6: a) Firststep :Sensitisation 100 g of cut hair (2 cm lengths) are immersed in two litres of methanol.

The solution is heated to the boil and reflux is maintained for twelve hours.

The hair is filtered off; it is dried at ambient temperature.

b) Second step: Enzymatic digestion An identical procedure to that of Example 1 is used.

The results obtained are as follows: 1) enzymatic digestion efficiency: unsensitised control hair : 5% sensitised hair :16% 2) characterisation ofthe keratin hydrolysate: cysti ne content of the hydrolysate: 60 x 10-3 mols per 100 g of total protein material cystine content of the initial keratin: 62 x 10-3 mols per 100 g of total protein material Example 7: a) First step: Sensitisation An identical procedure to that of Example 6 is used, but the sensitisation is continued for twenty-four hours.

b) Second step: Enzymatic digestion An identical procedure to that of Example 1 is used.

The results obtained are as follows: 1) enzymatic digestion efficiency: unsensitised control hair : 5% sensitised hair : 19% 2) characterisation ofthe keratin hydrolysate: cystine content of the hydrolysate: 58x 10-3 mols per 100 g of total protein material cystine content of the intial keratin: 62x 10-3 mols per 100 g of total protein material Example 8: a) Firststep: Sensitisation 100 g of cut hair (2 cm lengths) are immersed in two litres of formic acid, preheated to 90"C.

The solution is heated to the boil and reflux is maintained for thirty minutes.

The hair is filtered off; it is washed copiously with demineralised water and then with alcohol and ether. It is dried at ambient temperature.

b) Second step: Enzymatic digestion An identical procedure to that of Example 1 is used.

The results obtained are as follows: 1) enzymatic digestion efficiency: unsensitised control hair : 5% sensitised hair : 14% 2) characterisation ofthe keratin hydrolysate: cystine content of the hydrolysate: 59 x 10-3 mols per 100 g of total protein material cystine content ofthe initial keratin: 62 x 10-3 mols per 100 g oftotal protein material Example 9: a) Firststep: Sensitisation 100 g of cut hair (2 cm lengths) are immersed in two litres of formic acid, preheated to 90"C.

The solution is heated to the boil and relux is maintained for thirsty minutes.

The hair is filtered off. It is re-immersed in two litres of formic acid and stirred for 16 hours at ambient temperature.

The hair is filtered off; it is washed copiously with demineralised water and then with alcohol and ether. It is dried at ambient temperature.

p) Second step: Enzymatic digestion An identical procedure to that of Example 1 is used.

The results obtained are as follows: 1) enzymatic digestion efficiency: unsensitised control hair : 5% sensitised hair : 23% 2) characterisation of the keratin hydrolysate: cystine content of the hydrolysate: 57 x 10-3 mols per 100 g of total protein material cystine content of the initial keratin: 62 x 10-3 mols per 100 g of total protein material Example 10: a) First step: Sensitisation A solution of lithium bromide is prepared by solubilising 1,737 g of LiBr in demineralised water, the volume being adjusted to two litres.

100 g of cut hair (2 cm lengths) are immersed in the two litres of sensitising solution, preheated to 900C.

The solution is heated to the boil and reflux is maintained for one hour.

The hair is filtered off; it is washed copiously with hot demineralised water and then with alcohol and ether. It is dried at ambient temperature.

b) Second step: Enzymatic digestion An identical procedure to that of Example 1 is used.

The results obtained are as follows: 1) enzymatic digestion efficiency: unsensitised control hair : 5% sensitised hair : 75% 2) characterisation ofthe keratin hydrolysate: cystine content of the hydrolysate: 53 x 10-3 mols per 100 g of total protein material cystine content ofthe initial keratin: 62x 10-3 mols per 100 g of total protein material Example 11: a) First Step: Sensitisation A solution of lithium bromide is prepared by solubilising 1,390 g of LiBr in demineralised water and adjusting the volume to two litres.

100 g of cut hair(2 cm lengths) are immersed in the two litres of sensitising solution, preheated to 900C.

The solutiori is heated to the boil and reflux is maintained for four hours.

The hair is filtered off; it is washed copiously with hot demineralised water and then with alcohol and ether. It is dried at ambient temperature.

b) Second step: Enzymatic digestion An identical procedure to that of Example 1 is used.

The results obtained are as follows: 1) enzymatic digestion efficiency: unsensitised control hair : 5% sensitised hair :15% 2) characterisation ofthe keratin hydrolysate: cystine content of the hydrolysate: 54x 10-3 mols per 100 g oftotal protein material cystine content of the initial keratin: 62 x 10-3 mols per 100 g of total protein material Example 12: a) Firststep: Sensitisation A solution of lithium bromide is prepared by solubilising 1,737 g of LiBr in demineralised water, the volume being adjusted to two litres.

100g of cut hair (2 cm lengths) are immersed in the two litres of the sensitising solution.

The solution is heated to 100 C and then kept at this temperature for sixteen hours.

The hair is filtered off; it is washed copiously with hot demineralised water and then with alcohol and ether. It is dried at ambient temperatu re.

b) Second step: Enzymatic digestion An identical procedure to that of Example 1 is used.

The results obtained are as follows: 1) enzymatic digestion efficiency: unsensitised control hair : 5% sensitised hair : 13% 2) characterisation ofthe keratin hydrolysate: cystine content of the hydrolysate: 60 x 10-3 mols per 100 g of total protein material cystine content of the initial keratin: 62 x 10-3 mols per 100g of total protein material Example 13: a) Firststep: Sensitisation An identical procedure to that of Example 10 is used.

After reflux for one hour in the lithium bromide solution, the hair is filtered off and then washed copiously with hot demineralised water and with alcohol.

It is then immersed in two litres of dimethylformamide, preheated to 140"C. The solution is heated to the boil and reflux is maintained for thirty minutes.

The hair is filtered off; it is rinsed several times with demineralised water and then with alcohol and ether.

It is dried at ambient temperature.

b) Second step: Enzymatic digestion An identical procedure to that of Example 1 is used.

The results obtained are as follows: 1) enzymatic digestion efficiency: unsensitised control hair : 5% sensitised hair : 91% 2) characterisation of the keratin hydrolysate: cystine content of the hydrolysate: 50 x 10-3 mols per 100 g of total protein material cystine content of the initial keratin.

62 x 10-3 mols per 100 g of total protein material Example 14: a) Firststep: Sensitisation A solution of lithium bromide is prepared by solubilising 1,737-9 of LiBr in demineralised water, the volume being adjusted to two litres. - 100 g of powdered horn are immersed in the two litres of sensitising solution, preheated to 900C.

The solution is heated to the boil and reflux is maintained for one hour.

The powdered horn is filtered off; it is washed copiously with hot demineralised water and then with alcohol and ether. Itis dried at ambient temperature.

b) Second step: Enzymatic digestion An enzymatic solution containing the proteinase "PSF 2019" (Societe ORIL - PARIS) is prepared just before use. Its formula is as follows: Purified proteinase "PSF 2019" (11,000 Anson units/mg) 2.5 g Tris-(hydroxymethyl)-aminomethane 24.2 g HCI (normal solution) 55 ml MgCl2.6H20 0.03g Demineralised water q.s.p. 2,000 ml The powdered horn presensitised with lithium bromide is immersed in the enzymatic solution, heated to 400C. A stirrer provides continuous stirring.

The digestion lasts four days.

The insoluble residue is filtered off and the solution is neutralised.

The results obtained are as follows: 1) enzymatic digestion efficiency: unsensitised powdered horn (control) : 46% sensitised powdered horn : 62% 2) characterisation ofthe keratin hydrolysate: cystine content of the hydrolysate: 25x 10-3 mols per 100g oftotal protein material cystine content of the initial keratin: 31 x 10-3 mols per 100 g of total protein material Example 15: a) First step: Sensitisation 100g of powdered horn are immersed in two litres of dimethylformamide, preheated to 120 C.

The solution is left for four hours at 120"C.

The powdered horn is filtered off; it is rinsed several times with demineralised water and then with alcohol and ether. It is dried at ambient temperature.

b) Second step: Enzymatic digestion An enzymatic solution containing chymotrypsin is prepared just before use.

Its formula is as follows: Alpha-chymotrypsin (47 pImg) 1.5 g Tris-(hydroxymethyl)-aminomethane 24.2 g HCI (normal solution) 100 ml Demineralised water q.s.p. 2,000 ml The powdered horn presensitised with dimethylformamide is immersed in the enzymatic solution, heated to 40"C. A stirrer provides continuous stirring.

The digestions lasts four days.

The insoluble residue is filtered off and the solution is neutralised.

The results obtained are as follows: 1) enzymatic digestion efficiency: unsensitised powdered horn (control) : 18% sensitised powdered horn : 35% 2) characterisation ofthe keratin hydrolysate: cystine content of the hydrolysate: 24x 10-3 mols per 100 g of total protein material cystine content of the initial keratin: 31 x 10mols per 100 g oftotal protein material Example 16: a) First step: Sensitisation 100 g of clean rabbit are immersed in two litres of dimethylformamide, preheated ta 1200C.

The solution is left for three hours at 120"C.

The rabbit fur is filtered off; it is rinsed several times with demineralised water and then with alcohol and ether. It is dried at ambient temperature.

b) Second step: Enzymatic digestion An enzymatic solution containing Pronase (KOCH-LIGHT) is prepared just before use.

Its formula is as follows: Pronase (from Streptomyces griseus) 2.4 g Boric acid (H3BO3) 225 g Normal sodium hydroxide solution 130 ml MgCl2. 6H20 O.03g Demineralised water q.s.p. 2,000 ml The rabbit fur presensitised with dimethylformamide is immersed in the enzymatic solution, heated to 40"C. A stirrer provides continuous stirring.

The digestion lasts four days.

The insoluble residue is filtered off and the solution is neutralised.

The results obtained are as follows: 1) enzymatic digestion efficiency: unsensitised rabbit fur (control) : 4% sensitised rabbit fur :78% 2) characterisation ofthe keratin hydro/ysate: cystine content of the hydrolysate: 23.5 x 10-3 mols per 100 g of total protein material cystine content of the initial keratin: 31 x 10-3 mols per 100 g of total protein material Example 17: a) First step: Sensitisation A solution of lithium bromide is prepared by dissolving 1,737 g of LiBr in demineralised water, the volume being adjusted to two litres.

100 g of clean rabbit fur are immersed in the two litres of sensitising solution, preheated to 90"C.

The solution is heated to the boil and reflux is maintained for one hour.

The rabbit fur is filtered off; it is washed copiously with hot demineralised water and then with alcohol and ether. It is dried at ambient temperature.

b) Second step: Enzymatic digestion - An enzymatic solution containing trypsin is prepared just before use: Its formula is as follows: Puretrypsin )3171l/mg) 15g Boric acid (H3BO3) 50 g Normal sodium hydroxide solution 290 ml Demineralised water q.s.p. 5,000 ml The rabbit fur presensitised with lithium bromide is immersed in the enzymatic solution, heated to 400C. A stirrer provides continuous stirring.

The digestion lasts four days.

The insoluble residue is filtered off and the solution is neutralised.

The results obtained are as follows: 1) enzymatic digestion efficiency: unsensitised rabbit fur (control) : 3% sensitised rabbit fur : 33% 2) characterisation ofthe keratin hydrolysate: cystine content of the hydrolysate: 25x 10 3 mols per 100 g of total protein material cystine content of the initial keratin: 31 x 10-3 mols per 100 g oftotal protein material Example 18: a) First step: Sensitisation 100 g of poultry feathers (down) are immersed in two litres of dimethylformamide, preheated to 120"C.

The solution is leftforfour hours at 1200C.

The feathers are filtered off; they are rinsed several times with demineralised water and then with alcohol and ether. They are dried at ambient temperature.

b) Second step: Enzymatic digestion An enzymatic solution containing Pronase (KOCH-LIGHT) is prepared just before used.

Its formula is as follows: Pronase (from Streptomyces griseus) 2.4 g Tris-(hydroxymethyl)-aminomethane 24.2 g HCI (normal solution) 55 ml Mg:Cl2.6H2O 0.03g Demineralised water q.s.p. 2,000 ml The feathers presensitised with dimethyl-formamide are immersed in the enzymatic solution, heated to 40 C. A stirrer provides continuous stirring.

The digestion lasts four days.

The insoluble residue is filtered off and the solution is neutralised.

The results obtained are as follows: 1) enzymatic digestion efficiency: unsensitised control feathers: 10% sensitised feathers: 27% 2) characterisation ofthe keratin hydrolysate: cystine content of the hydrolysate: 31.5 x 10-3 mols per 100 g of total protein material cystine content of the initial keratin: 34 x 1--3 mols per 100 g of total protein material The protein hydrolysates have a beneficial influence on the hair when they form part of the composition of care or treatment products. The positive physiological and cosmetic effects can be explained by the formation of a more or less ordered deposit on the cuticle of the hair, which thus protects the hair from chemical or physico-chemical attack and imparts appreciable styling qualities thereto.The keratin hydrolystes which have a sulphur-rich formula are very similar to the hair, as regards their chemical composition, and thus constitute the ideal proteins for hair care.

Two examples of the use of the keratin hydrolysates according to the invention are now given below.

Example 19: Vitalisinglotion The lotion has the following formulation: Keratin hydrolysate ........................................ 1 g Polyoxyethyleneated oleyl ether containing 20 mols of ethylene oxide (sold under the name "BRIJ 98" by ATLAS) ........................................ 0.1 g Acetic acid q.s.p.............................. pH 7 Dyestuff ...................................... 0.1 g Perfume ....................................... 0.1 g Alcohol (96 strength) ......................... 10 ml Demineralised water q.s.p. .................... 100 ml The lotion is applied to the hair. Slight massaging makes it possible to spread the liquid well. Drying is carried out at ambient temperature or under a hood.

Example 20: Rinsing Lotion The lotion has the following formulation: Keratin hydrolysate ........................................ 1 g Polyoxyethyleneated oleyl ether containing 20 mols of ethylene oxide (sold under the name "BRIJ 98" by ATLAS) ........................................ 0.1 g Acetic acid q.s.p ............................. pH 7 Dyestuff ...................................... 0.1 g Perfume ....................................... 0.1 g Demineralised water q.s.p. .................... 100 ml This lotion is applied to clean hair in a homogeneous manner. After an interval of about 5 minutes, the hair is rinsed with water and dried under a hood.

The effects of the keratin hydrolysates according to the invention and prior art keratin hydrolysates were compared. For this purpose, the microstructures deposited on the surface were studied and three types of keratin hydrolysates were compared in the lotions of Examples 19 and 20, namely the hydrolysate prepared in accordance with Example 2, a keratin hydrolysate prepared using hydrochloric acid, and an enzymatic hydrolysate prepared from a cystine-poor degraded keratin.

On the arbitrary scale used, the cosmetic region lies between 0 and 50. The closer the number is to 0, the better is the quality of the deposit.

Hydrolysate used Vitalising Rinsing lotion lotion applied to applied to bleached bleached hair hair (Example 19) (Example 20) Keratin hydrolysate pre pared on accordance with Example2-cystine-rich 19 11 (1 ,000 < molecular weight < 5,000) Hydryolysate prepared using hydrochloric acid (average molecular 48 31 weight#130) Enzymatic hydrolysate of degraded keratin cystine-poor )1,000 < mole cular weight < 5,000) 65 49 It is apparent that the keratin hydrolysate prepared in accordance with Example 2 is the one having the most cosmetic deposit. Hair treated in this way is not weighed down by the deposit and acquires appreciable qualities.

Claims (14)

1. Process for the preparation of an oligopeptide composition by the hydrolysis of a keratin material, which comprises subjecting the keratin material to a sensitising treatment carried out with an electrolyte in an aqueous medium at a concentration of at least 8 mols per litre, or with a polar solvent, or where the keratin material is in the form of keratin with a cuticle, either to a sensitising treatment as defined above or to a treatment with at least one cuticle-removing agent which is ultrasound or formic acid at a concentration of at least 90% by weight, as cuticle-removing agent, and, subsequently treating the material with proteolytic and/or keratolytic enzyme.

2. Process according Claim 1, in which the electrolyte used is lithium bromide.

3. Process according to Claim 1, in which, during the sensitising treatment, the polar solvent constitutes at least 75% by weight of the medium in which the treatment is carried out.

4. Process according to Claim 1 or-3, in which the polar solvent is dimethylformamide or methanol.

5. Process according to any one of Claims 1 to 4, in which the sensitising treatment is carried out by means of at least one electrolyte and/or at least one polar solvent and is carried out for more than 30 minutes at a temperature from ambient temperature to the reflux temperature of the medium at atmospheric pressure.

6. Process according to Claim 1, in which the cuticle-removing agent is formic acid, and the sensitising treatment is carried out for more than 30 minutes at a temperature from ambient temperature to the reflux temperature at atmospheric pressure.

7. Process according to Claim 1, in which the cuticle-removing agent is an ultrasonic emission, having a frequency of 20 KHz to 70 KHz and the treatment lasts more than 30 minutes, the dissipated power being 50 to 150 watts per dm3 treated.

8. Procss according to any one of Claims 1 to 7, in which the enzymatic treatment is carried out at a pH not exceeding 9, at a temperature below 50"C and with an active concentration of enzymes.

9. Process according to Claim 8, in which the enzymatic treatment lasts 20 hours to 90 hours.

10. Process according to Claim 1 substantially as described in any one of Examples 1 to 18.

11. An oligopeptide composition whenever prepared by a process as claimed in any one of the preceding claims.

12. An oligopeptide composition according to Claim 11, in which at least 75% by weight of the oligopeptides present therein have a molecular weight of 1,000 to 5,000 and the composition contains at least 30% by weight of the cystine groups present in the keratin material used as the raw material.

13. A method of treating the hair or skin which comprises applying thereto a composition as claimed in claim 11 or 12.

14. Use of a composition as claimed in Claim 11 or 12 in the food industry.