Compositions, uses, methods, and system for treating animal hides

Abstract

A method of treating an animal hide, the method comprising steps of: (a) soaking the animal hide in an alkaline soaking composition; (b) optionally removing the alkaline soaking composition from the animal hide; (c) optionally contacting the animal hide with a pre-liming composition; and (d) contacting the animal hide with a liming composition comprising sulfide ions or a source thereof; wherein the alkaline soaking composition and / or the pre-liming composition comprises a biosurfactant compound.

Description

[0001] COMPOSITIONS AND METHODS AND USES RELATING THERETO

[0002] The present invention relates to compositions and methods useful in the treatment of animal hides.

[0003] Leather obtained from the hides of animals is widely used throughout the world for clothing, accessories and other purposes. Once a hide has been removed from an animal it is typically preserved using salt before being transported to a tannery. In the tannery a number of steps are undertaken. Typically the salt is removed mechanically and / or by washing and the hide is then soaked to remove salts and fats and to swell the skin before a liming process is carried out. Liming is carried out to remove animal hair and other keratins from the hide.

[0004] Traditional liming processes use sodium sulfide as a depilatory agent on a large scale, typically in an amount of from 2 to 4 % based on the weight of the hide. However there are a number of reasons why this is undesirable. Sodium sulfide is classified as hazardous to health and is harmful to the environment. As it is also harmful to aquatic life, extra steps are needed in the treatment of waste. In addition the presence of remaining sodium sulfide can be detrimental to the quality of the leather product. Sodium sulfide may react with fungicides added in the manufacturing process and make the leather more vulnerable to fungal contamination. Sodium sulfide may also release hydrogen sulfide gas, posing further health and operational risks. Hydrogen sulfide is a toxic gas and is also able to self-ignite.

[0005] There is a desire to provide a tanning process which has an improved environmental and safety profile but which maintains acceptable levels of depilation.

[0006] US2024 / 0117562 describes the use of a biosurfactant as an adjuvant in leather treatment processes. Various effects and methods are described but details of how to use the adjuvant and in what stage of the process are not provided.

[0007] The present inventors have surprisingly found that the inclusion of a biosurfactant compound such as a sophorolipid in a composition used to treat animal hides prior to a liming step can significantly reduce the amount of sodium sulfide needed to achieve depilation.

[0008] The present inventors have found that the contact of animal hide with a composition comprising a biosurfactant can reduce the concentration of sodium sulfide needed to achieve depilation. Surprisingly depilation is improved when a biosurfactant is used in a pre-treatment step but no such improvement is achieved when the biosurfactant is first contacted with the animal hide at the same time as the composition comprising the sodium sulfide.In some embodiments a biosurfactant compound may be included in a soaking composition. In some embodiments an additional step of treating the animal hide with a composition comprising a biosurfactant compound after the soaking step but before the liming step may be carried out.

[0009] According to a first aspect of the present invention, there is provided a method of treating an animal hide, the method comprising the steps of:

[0010] (a) soaking the animal hide in an alkaline soaking composition;

[0011] (b) optionally removing the alkaline soaking composition from the animal hide;

[0012] (c) optionally contacting the animal hide with a pre-liming composition; and

[0013] (d) contacting the animal hide with a liming composition comprising sulfide ions or a source thereof;

[0014] wherein the alkaline soaking composition and / or the pre-liming composition comprises a biosurfactant compound.

[0015] The present invention involves the use of a biosurfactant compound.

[0016] By “biosurfactant” we mean to refer to a surfactant compound which is produced by a living cell and / or using naturally-derived substrates.

[0017] Biosurfactants include a polar (hydrophilic) moiety and a non-polar (hydrophobic) group. Typically, the hydrophilic group of a biosurfactant is a sugar (e.g., a mono-, di-, or polysaccharide) or a peptide, while the hydrophobic group is typically a fatty acid. Thus a large variety of biosurfactant molecules exist based on, for example, type of sugar, number of sugars, size of peptides, which amino acids are present in the peptides, fatty acid length, saturation of fatty acids, additional acetylation, additional functional groups, esterification, polarity and charge of the molecule.

[0018] Preferred biosurfactants for use herein include glycolipids (e.g., sophorolipids, rhamnolipids, cellobiose lipids, mannosylerythritol lipids and trehalose lipids), lipopeptides (e.g., surfactin, iturin, fengycin, arthrofactin and lichenysin), flavolipids, phospholipids (e.g., cardiolipins), fatty acid ester compounds, and high molecular weight polymers such as lipoproteins, lipopolysaccharide-protein complexes, and polysaccharide-protein-fatty acid complexes.

[0019] Preferred biosurfactants for use herein are sophorolipids.

[0020] The term sophorolipid as used herein includes acidic (linear) sophorolipids, lactonic sophorolipids, mono-acetylated sophorolipids, di-acetylated sophorolipids, esterified sophorolipids, sophorolipids with varying hydrophobic chain lengths, cationic and / or anionic sophorolipids with fatty acid-amino acid complexes attached, sophorolipid-metal complexes,sophorolipid salts, sophorolipid amino alcohols, sophorolipids with carbonyl groups removed from the aliphatic chain, and other derivatives thereof.

[0021] Other preferred features of the biosurfactant compounds useful in the present invention are further defined herein.

[0022] The method of the present invention is suitably carried out in a tannery. The method of the present invention can be used to treat fresh hides which have not been treated to preserve them. However animal hides commonly arrive at a tannery in a preserved form and typically require salt removal before the soaking step. In some embodiments, the salt may be simply brushed or scraped from the hide. In preferred embodiments thorough washing of the hide is carried out to achieve salt removal. This may involve soaking for a prolonged period, optionally with stirring. A particular advantage of the present invention is that good depilation can be achieved even when the hide has a high level of residual salt. This is not always possible using processes of the prior art.

[0023] The steps of the method of the present invention are suitably not carried out simultaneously. Suitably they are carried out sequentially. Thus step (a) is carried out first, followed by step (b) when present, then step (c) when present, and finally step (d) is carried out.

[0024] Step (a) of the method in the present invention involves soaking the animal hide in an alkaline soaking composition.

[0025] The soaking composition is an alkaline composition. Preferably the soaking composition has a pH of at least 8, preferably at least 9. Suitably the soaking composition has a pH of from 9 to 12, for example from 10 to 11.

[0026] Suitable components for inclusion in an animal soaking composition will be known to the person skilled in the art.

[0027] The alkaline soaking composition preferably comprises one or more components selected from enzymes, surfactants, amino compounds, phosphate compounds, alkali metal or alkaline earth metal salts, bactericides and mixtures thereof.

[0028] The alkaline soaking composition may comprise an enzyme. It may comprise a mixture of two or more enzymes. Suitable enzymes will be known to the person skilled in the art.Suitable enzymes may include, for example chondroitinases, amidases, phospholipases, xylanase, mannanase, zymase, maltase, pectinase, elastase, hyaluronidase and a-galactosidase.

[0029] Especially suitable enzymes for use in the alkaline soaking composition are proteolytic, lipolytic and microbial enzymes.

[0030] Preferred enzymes for use in the alkaline soaking composition are hydrolase, proteolytic and microbial enzymes.

[0031] Preferred enzymes for use in the alkaline soaking composition are amylase, lipase and / or protease.

[0032] The alkaline soaking composition may comprise one or more surfactants. For the avoidance of doubt these one or more further surfactants may be included in addition to the biosurfactant which is optionally present. Suitable surfactants include cationic surfactants, anionic surfactants, non-ionic surfactants, amphoteric surfactants and mixtures thereof. Preferred surfactants are anionic surfactants, non-ionic surfactants, amphoteric surfactants and mixtures thereof.

[0033] The alkaline soaking composition may comprise a mixture of two or more anionic surfactants and / or two or more non-ionic surfactants and / or two or more amphoteric surfactants.

[0034] In preferred embodiments the alkaline soaking composition comprises at least one anionic surfactant and at least one non-ionic surfactant.

[0035] Any suitable anionic surfactant may be included. Such compounds will be known to the person skilled in the art.

[0036] Suitable anionic surfactants for use herein include salts of: fatty acids; alkoxylated carboxylic acids; ester carboxylates; ethoxylated ester carboxylates; mono- or dialkyl sulfates; mono- or dialkyl ether sulfates; lauryl ether sulfates; alkyl sulfonates; alkyl aryl sulfonates; primary alkane disulfonates; alkene sulfonates; hydroxyalkane sulfonates; isethionates, alkyl isethionates, acyl isethionates, acyl (alkyl) isethionates, alkyl glyceryl ether sulfonates; alpha-olefin sulfonates; alkyl phosphates; sulfonates of alkylphenolpolyglycol ethers; alkyl sulfopolycarboxylic acid esters; alkyl sulfosuccinates; alkyl ether sulfosuccinates; taurates; acyl taurates; acyl alkyl taurates; products of condensation of fatty acids with oxy- and aminoalkanesulfonic acids; sulfated derivatives of fatty acids and polyglycols; alkyl and acyl sarcosinates; sulfoacetates; alkyl phosphates; alkyl phosphate esters; acyl lactates; alkanolamides of sulfated fatty acids, lipoamino acids and acyl substituted amino acids, for example acyl glycinates and acylglutamates. Particularly exemplary salts, where applicable, are the sodium, potassium, ammonium, magnesium and triethanolamine salts.

[0037] Preferred anionic surfactants include alkyl or alkenyl sulfates, alkyl aryl sulfonates, alkyl sulfonates, alkyl or alkenyl ether sulfates, alkyl glyceryl ether sulfates, taurates, acyl taurates, acyl (alkyl) taurates, (alkyl) isethionates, acyl (alkyl) isethionates, acyl substituted amino acids, sarcosinates, sulfosuccinates, sulfosuccinamates, sulphoacetates, monoalkyl phosphate esters, di-alkyl phosphate esters, mono-alkyl ether phosphate esters, di-alkyl ether phosphate esters, alpha-olefin sulfonates, acyl lactates, alkyl ether carboxylates and glyceryl ether carboxylates.

[0038] Particularly preferred anionic surfactants for use in the alkaline soaking composition include alkyl or alkenyl sulfates, alkyl aryl sulfonates, alkyl sulfonates, alkyl or alkenyl ether sulfates, alphaolefin sulfonates, taurates, isethionates, acyl substituted amino acids, sarcosinates, acyl lactates and sulfosuccinates.

[0039] References herein to taurate surfactants or acyl taurates include compounds such as sodium lauroyl methyl taurate, sodium methyl cocoyl taurate and sodium methyl oleoyl taurate which could also be regarded as alkyl acyl taurates.

[0040] Suitable alkyl or alkenyl sulfates and ether sulfates are compounds of formula:

[0041] R1CH2(OR2)nOSO3M

[0042] wherein R1is a C5 to C39 alkyl or alkenyl group, R2is an alkylene group having 1 to 4 carbon atoms and n is from 0 to 12.

[0043] Preferably R1is a C7 to C15 alkyl or alkenyl group or a C9 to C13 alkyl or alkenyl group, suitably an alkyl group. For example, R1may be a C11 alkyl group.

[0044] R2is preferably a propylene or especially an ethylene moiety. Preferably n is from 0 to 6, preferably from 0 to 4, for example from 0 to 3. In some embodiments n is 0. In some embodiments n is 2. The skilled person will understand that alkyl or alkenyl ether sulfates typically contain mixtures of compounds with different n numbers due to the statistical nature of the alkoxylation reaction used in their formation. Some molecules are not alkoxylated in such a reaction and therefore some molecules wherein n = 0 may be present, e.g. alkyl sulfate

[0045] In some preferred embodiments, n is 2 or 3, or a mixture of compounds wherein n is 2 and compounds wherein n is 3.In some preferred embodiments, n is 1.

[0046] The above n numbers suitably represent an average n number of a mixture of such alkyl or alkenyl sulfates and ether sulfates.

[0047] Preferred anionic surfactants are linear alkylbenzene sulfonates. Particularly preferred are sodium salts of alkylbenzene sulfonic acids in which the alkyl group has 4 to 36, preferably 6 to 24 carbon atoms, more preferably 8 to 16 carbon atoms, most preferably 10 to 14, for example 12 carbon atoms.

[0048] Most preferred anionic surfactants for use in the alkaline soaking composition are dodecylbenzene sulfonate and sodium lauryl ether sulfate.

[0049] Suitable non-ionic surfactants for inclusion in the alkaline soaking composition will be known to the person skilled in the art.

[0050] Suitable non-ionic surfactants include polyethylene glycol, alkyl alkoxylates, alkenyl alkoxylates, C6-C22 alcohol condensates with ethylene oxide / propylene oxide block polymers; C14-C22 mid-chain branched alcohols, C14-C22 mid-chain branched alkyl alkoxylate, alkylpolysaccharides, (for example alkylpolyglycosides), methylester ethoxylates, polyhydroxy fatty acid amides, ether capped poly(oxyalkylated) alcohol surfactants, acyl polyethoxylated-glycerol esters (for example cocoyl POE-glycerol esters) and mixtures thereof.

[0051] In some embodiments, the non-ionic surfactant may be a condensation product of straight or branched chain fatty alcohols containing between 6 and 22 carbon atoms with between 4 and 30 moles of ethylene oxide having a HLB between 8 and 15.

[0052] Preferably the non-ionic surfactant comprises an alkoxylated compound. Preferably the alkoxylated non-ionic surfactants comprises at least two alkoxy residues, preferably at least two ethoxy residues.

[0053] Suitable alkoxylated non-ionic surfactants include any compound comprising one or more alkylene oxide residue and a hydrophobic group. Preferred non-ionic surfactants are compounds which include one or more ethylene oxide and / or propylene oxide residue and a hydrophobic group. Suitable non-ionic surfactants may be formed by the reaction of aliphatic alcohols, acids or amides with alkylene oxides. Preferably the hydrophobic group comprises a hydrocarbon chain having at least 4 carbon atoms, preferably at least 5 carbon atoms, more preferably at least 6 carbon atoms. Preferably the hydrophobic group comprises from 6 to 30 carbon atoms, more preferably from 6 to 21 carbon atoms, most preferably from 8 to 18 carbonatoms. Preferably the hydrophobic group is an alkyl group. The non-ionic surfactant may include more than one hydrophobic residue.

[0054] Preferred non-ionic surfactants for use herein are alkoxylated alcohols prepared from a C8 to C20 alcohol and 2 to 16 equivalents of ethylene oxide.

[0055] Suitable non-ionic surfactants are alkoxylated alcohols include C10-C14, especially a C10 alcohol ethoxylated with 6 to 10, preferably 8 equivalents of ethylene oxide.

[0056] Suitable amphoteric surfactants for use in the alkaline soaking composition will be known to the person skilled in the art. Preferred amphoteric surfactants are amine oxides, for example lauramine oxide and myristamine oxide.

[0057] The alkaline soaking composition may comprise an amino compound.

[0058] The amino compound may be selected from any compound containing an amino or substituted amino moiety, for example ammonia, an aliphatic or aromatic amine, an amide or urea.

[0059] Suitable amino compounds include natural compounds and synthetic compounds. A mixture of two or more amino compounds may be used.

[0060] Suitable amines include aromatic and aliphatic amines. These amines may be substituted or unsubstituted. Examples of suitable amines include amino acids, alkanolamines, alkyl amines and alkenyl amines. Especially preferred amines for use herein are alkyl amines and alkanolamines.

[0061] The amino compound may be selected from ammonia, a primary amine, a secondary amine or a tertiary amine.

[0062] A preferred amino compound for use herein is urea.

[0063] The alkaline soaking composition may comprise one or more alkali metal or alkaline earth metal salts. Suitable salts include sodium, potassium, magnesium and calcium salts of carbonate, sulfate, hydroxide, nitrate, phosphate and halide (for example chloride or bromide) anions.

[0064] Preferred salts are calcium salts. Preferred calcium salts include calcium carbonate, calcium hydroxide and mixtures thereof.The alkaline soaking composition may comprise a bactericide. Suitable bactericides will be known to the person skilled in the art and include, for example, bronopol, dithiocarbamate, omidine sodium and zinc pyrithione.

[0065] The alkaline soaking composition may comprise a phosphate compound. Suitable phosphate compounds will be known to the person skilled in the art and include, for example, alkaline polyphosphates such as sodium hexametaphosphate.

[0066] In some embodiments the alkaline soaking composition may further comprise a biosurfactant compound. Suitable biosurfactants are further defined herein.

[0067] According to a second aspect of the present invention there is provided an alkaline soaking composition comprising one or more components selected from enzymes, surfactants, amino compounds, phosphate compounds, alkali metal or alkaline earth metal salts, bactericides and mixtures thereof; and a biosurfactant compound.

[0068] According to a third aspect of the present invention there is provided an alkaline soaking concentrate composition comprising one or more components selected from enzymes, surfactants, amino compounds, phosphate compounds, alkali metal or alkaline earth metal salts, bactericides and mixtures thereof; and a biosurfactant compound.

[0069] Upon dilution the concentrate composition of the third aspect suitably provides an alkaline soaking composition of the second aspect. The concentrate composition of the third aspect may be provided with instructions for preparing an alkaline soaking composition.

[0070] The alkaline soaking composition is suitably an aqueous composition. It is suitably prepared by diluting an alkaline soaking concentrate composition with water.

[0071] Preferred features of the second and third aspects are as defined in relation to the first aspect and further features of the alkaline soaking composition and the alkaline soaking concentrate composition of the second and third aspects also apply in relation to the first aspect.

[0072] The alkaline soaking composition suitably comprises one or more components selected from enzymes, surfactants, amino compounds, phosphate compounds, alkali metal or alkaline earth metal salts, bactericides and mixtures thereof.

[0073] Preferably the alkaline soaking composition comprises at least one surfactant. For the avoidance of doubt this at least one surfactant is present in addition to any biosurfactant which may be present.Preferably the alkaline soaking composition comprises at least one anionic surfactant, preferably a linear alkylbenzene sulfonate surfactant.

[0074] Preferably the alkaline soaking composition comprises at least one alkali metal or alkaline earth metal salt, preferably at least one calcium salt.

[0075] Preferably the alkaline soaking composition comprises at least one alkali metal or alkaline earth metal hydroxide or carbonate salt.

[0076] Preferably the alkaline soaking composition comprises calcium hydroxide and calcium carbonate.

[0077] Preferably the alkaline soaking composition comprises calcium hydroxide, calcium carbonate and a linear alkylbenzene sulfonate surfactant.

[0078] Preferably the ratio of hydroxide salts to carbonate salts present in the alkaline soaking composition is from 5:1 to 1 :5, preferably from 2:1 to 1 :2.

[0079] Preferably the ratio of calcium hydroxide to calcium carbonate present in the alkaline soaking composition is from 5:1 to 1 :5, preferably from 2:1 to 1 :2.

[0080] Preferably the ratio of alkali metal or alkaline earth metal salts to anionic surfactants present in the alkaline soaking composition is from 60:1 to 1 :5, preferably from 30:1 to 1 :1 , for example from 20:1 to 10:1.

[0081] Preferably the ratio of calcium salts to linear alkylbenzene sulfonate surfactants present in the alkaline soaking composition is from 60:1 to 1 :5, preferably from 30:1 to 1 :1 , for example from 20:1 to 10:1.

[0082] The alkaline soaking concentrate composition comprises one or more components selected from enzymes, surfactants, amino compounds, phosphate compounds, alkali metal or alkaline earth metal salts, bactericides and mixtures thereof.

[0083] Preferably the alkaline soaking concentrate composition comprises at least one surfactant.

[0084] Preferably the alkaline soaking concentrate composition comprises at least one anionic surfactant, preferably a linear alkylbenzene sulfonate surfactant. For the avoidance of doubt this surfactant is present in addition to any biosurfactant which may be present.Preferably the alkaline soaking concentrate composition comprises at least one alkali metal or alkaline earth metal salt, preferably at least one calcium salt.

[0085] Preferably the alkaline soaking concentrate composition comprises at least 10 wt% alkali metal or alkaline earth metal salts, preferably at least 20 wt%, preferably at least 30 wt%.

[0086] Preferably the alkaline soaking concentrate composition comprises up to 90 wt% alkali metal or alkaline earth metal salts, preferably up to 80 wt%, preferably up to 70 wt%.

[0087] Preferably the alkaline soaking concentrate composition comprises from 10 to 90 wt% alkali metal or alkaline earth metal salts, preferably from 30 to 80 wt%, preferably from 40 to 75 wt%.

[0088] Preferably the alkaline soaking concentrate composition comprises from 10 to 50 wt% alkali metal or alkaline earth metal hydroxides, preferably from 20 to 40 wt%, preferably from 25 to 35 wt%.

[0089] Preferably the alkaline soaking concentrate composition comprises from 10 to 50 wt% alkali metal or alkaline earth metal carbonates, preferably from 20 to 40 wt%, preferably from 25 to 35 wt%.

[0090] Preferably the alkaline soaking concentrate composition comprises at least 10 wt% calcium salts, preferably at least 20 wt%, preferably at least 30 wt%.

[0091] Preferably the alkaline soaking concentrate composition comprises up to 90 wt% calcium salts, preferably up to 80 wt%, preferably up to 70 wt%.

[0092] Preferably the alkaline soaking concentrate composition comprises from 10 to 90 wt% calcium salts, preferably from 30 to 80 wt%, preferably from 40 to 75 wt%.

[0093] Preferably the alkaline soaking concentrate composition comprises calcium hydroxide and calcium carbonate.

[0094] Preferably the alkaline soaking concentrate composition comprises at least 10 wt% calcium hydroxide, preferably at least 15 wt%, preferably at least 20 wt%.

[0095] Preferably the alkaline soaking concentrate composition comprises up to 80 wt% calcium hydroxide, preferably up to 60 wt%, preferably up to 40 wt%.Preferably the alkaline soaking concentrate composition comprises from 10 to 50 wt% calcium hydroxide, preferably from 20 to 40 wt%, preferably from 25 to 35 wt%.

[0096] Preferably the alkaline soaking concentrate composition comprises at least 10 wt% calcium carbonate, preferably at least 15 wt%, preferably at least 20 wt%.

[0097] Preferably the alkaline soaking concentrate composition comprises up to 80 wt% calcium carbonate, preferably up to 60 wt%, preferably up to 40 wt%.

[0098] Preferably the alkaline soaking concentrate composition comprises from 10 to 50 wt% calcium carbonate, preferably from 20 to 40 wt%, preferably from 25 to 35 wt%.

[0099] Preferably the alkaline soaking concentrate composition comprises at least 10 wt% urea, preferably at least 15 wt%, preferably at least 20 wt%.

[0100] Preferably the alkaline soaking concentrate composition comprises up to 60 wt% urea, preferably up to 50 wt%, preferably up to 40 wt%.

[0101] Preferably the alkaline soaking concentrate composition comprises from 10 to 50 wt% urea, preferably from 20 to 40 wt%, preferably from 25 to 35 wt%.

[0102] Preferably the alkaline soaking concentrate composition comprises at least 0.1 wt% surfactants, preferably at least 0.5 wt%, preferably at least 1 wt%.

[0103] Preferably the alkaline soaking concentrate composition comprises up to 30 wt% surfactants, preferably up to 20 wt%, preferably up to 10 wt%.

[0104] Preferably the alkaline soaking concentrate composition comprises from 0.1 to 25 wt% surfactants, preferably from 0.5 to 12 wt%, preferably from 1 to 8 wt%.

[0105] Preferably the alkaline soaking concentrate composition comprises at least 0.1 wt% anionic surfactants, preferably at least 0.5 wt%, preferably at least 1 wt%.

[0106] Preferably the alkaline soaking concentrate composition comprises up to 25 wt% anionic surfactants, preferably up to 20 wt%, preferably up to 10 wt%.

[0107] Preferably the alkaline soaking concentrate composition comprises from 0.1 to 20 wt% anionic surfactants, preferably from 0.5 to 10 wt%, preferably from 1 to 6 wt%.Preferably the alkaline soaking concentrate composition comprises at least 0.1 wt% alkylbenzene sulfonate surfactants, preferably at least 0.5 wt%, preferably at least 1 wt%.

[0108] Preferably the alkaline soaking concentrate composition comprises up to 20 wt% alkylbenzene sulfonate surfactants, preferably up to 15 wt%, preferably up to 10 wt%.

[0109] Preferably the alkaline soaking concentrate composition comprises from 0.1 to 20 wt% alkylbenzene sulfonate surfactants, preferably from 0.5 to 10 wt%, preferably from 1 to 6 wt%.

[0110] Preferably the alkaline soaking concentrate composition comprises at least 0.1 wt% linear alkylbenzene sulfonate surfactants, preferably at least 0.5 wt%, preferably at least 1 wt%.

[0111] Preferably the alkaline soaking concentrate composition comprises up to 20 wt% linear alkylbenzene sulfonate surfactants, preferably up to 15 wt%, preferably up to 10 wt%.

[0112] Preferably the alkaline soaking concentrate composition comprises from 0.1 to 20 wt% linear alkylbenzene sulfonate surfactants, preferably from 0.5 to 10 wt%, preferably from 1 to 6 wt%.

[0113] Preferably the alkaline soaking concentrate composition comprises at least 0.01 wt% bactericide, preferably at least 0.05 wt%, preferably at least 0.1 wt%.

[0114] Preferably the alkaline soaking concentrate composition comprises up to 20 wt% bactericide, preferably up to 15 wt%, preferably up to 10 wt%.

[0115] Preferably the alkaline soaking concentrate composition comprises from 0.1 to 20 wt% bactericide, preferably from 0.5 to 10 wt%, preferably from 0.75 to 5 wt%.

[0116] Preferably the alkaline soaking concentrate composition comprises at least 0.1 wt% non-ionic surfactants, preferably at least 0.5 wt%, preferably at least 1 wt%.

[0117] Preferably the alkaline soaking concentrate composition comprises up to 30 wt% non-ionic surfactants, preferably up to 20 wt%, preferably up to 10 wt%.

[0118] Preferably the alkaline soaking concentrate composition comprises from 0.1 to 15 wt% non-ionic surfactants, preferably from 0.25 to 8 wt%, preferably from 0.5 to 4 wt%.

[0119] Preferably the alkaline soaking concentrate composition comprises at least 0.1 wt% alcohol ethoxylates, preferably at least 0.5 wt%, preferably at least 1 wt%.Preferably the alkaline soaking concentrate composition comprises up to 30 wt% alcohol ethoxylates, preferably up to 20 wt%, preferably up to 10 wt%.

[0120] Preferably the alkaline soaking concentrate composition comprises from 0.1 to 15 wt% alcohol ethoxylates, preferably from 0.25 to 8 wt%, preferably from 0.5 to 4 wt%.

[0121] Preferably the alkaline soaking concentrate composition comprises at least 0.01 wt% enzymes, preferably at least 0.05 wt%, preferably at least 0.1 wt%.

[0122] Preferably the alkaline soaking concentrate composition comprises up to 20 wt% enzymes, preferably up to 15 wt%, preferably up to 10 wt%.

[0123] Preferably the alkaline soaking concentrate composition comprises from 0.01 to 10 wt% enzymes, preferably from 0.1 to 2.5 wt%, preferably from 0.2 to 1 wt%.

[0124] In some embodiments the alkaline soaking concentrate composition further comprises a biosurfactant, preferably a sophorolipid surfactant.

[0125] Preferably the alkaline soaking concentrate composition comprises at least 0.1 wt% biosurfactant, preferably at least 1 wt%, preferably at least 2 wt%.

[0126] Preferably the alkaline soaking concentrate composition comprises up to 60 wt% biosurfactant, preferably up to 50 wt%, preferably up to 40 wt%.

[0127] Preferably the alkaline soaking concentrate composition comprises from 0.1 to 50 wt% biosurfactant, preferably from 1 to 40 wt%, preferably from 10 to 30 wt%.

[0128] Preferably the alkaline soaking concentrate composition comprises at least 0.1 wt% sophorolipid surfactant, preferably at least 1 wt%, preferably at least 2 wt%.

[0129] Preferably the alkaline soaking concentrate composition comprises up to 60 wt% sophorolipid surfactants, preferably up to 50 wt%, preferably up to 40 wt%.

[0130] Preferably the alkaline soaking concentrate composition comprises from 0.1 to 50 wt% sophorolipid surfactant, preferably from 1 to 40 wt%, preferably from 10 to 30 wt%.

[0131] Preferably the alkaline soaking concentrate composition comprises:

[0132] from 30 to 90 wt%, preferably from 40 to 80 wt% calcium salts;

[0133] from 10 to 50 wt%, preferably from 20 to 40 wt% urea;from 0.1 to 25 wt%, preferably from 0.5 to 12 wt% surfactants;

[0134] from 0.1 to 20 wt% preferably from 0.5 to 10 wt% bactericide; and

[0135] from 0.01 to 10 wt%, preferably from 0.1 to 2.5 wt% enzymes.

[0136] Preferably the alkaline soaking concentrate composition comprises:

[0137] from 10 to 50 wt%, preferably from 20 to 40 wt% calcium hydroxide;

[0138] from 10 to 50 wt%, preferably from 20 to 40 wt% calcium carbonate;

[0139] from 30 to 90 wt%, preferably from 20 to 40 wt% urea;

[0140] from 0.1 to 20 wt%, preferably from 0.5 to 10 wt% anionic surfactants;

[0141] from 0.1 to 15 wt%, preferably from 0.2 to 8 wt% non-ionic surfactants;

[0142] from 0.1 to 20 wt% preferably from 0.5 to 10 wt% bactericide; and

[0143] from 0.01 to 10 wt%, preferably from 0.1 to 2.5 wt% enzymes.

[0144] In some embodiments the alkaline soaking concentrate composition comprises:

[0145] from 30 to 90 wt%, preferably from 40 to 80 wt% calcium salts;

[0146] from 10 to 50 wt%, preferably from 20 to 40 wt% urea;

[0147] from 0.1 to 25 wt%, preferably from 0.5 to 12 wt% surfactants;

[0148] from 0.1 to 20 wt% preferably from 0.5 to 10 wt% bactericide;

[0149] from 0.01 to 10 wt%, preferably from 0.1 to 2.5 wt% enzymes; and

[0150] from 1 to 50 wt%, preferably from 5 to 40 wt% biosurfacant.

[0151] Preferably the alkaline soaking concentrate composition comprises:

[0152] from 10 to 50 wt%, preferably from 20 to 40 wt% calcium hydroxide;

[0153] from 10 to 50 wt%, preferably from 20 to 40 wt% calcium carbonate;

[0154] from 30 to 90 wt%, preferably from 40 to 80 wt% urea;

[0155] from 0.1 to 20 wt%, preferably from 0.5 to 10 wt% anionic surfactants;

[0156] from 0.1 to 15 wt%, preferably from 0.2 to 8 wt% non-ionic surfactants;

[0157] from 0.1 to 20 wt% preferably from 0.5 to 10 wt% bactericide;

[0158] from 0.01 to 10 wt%, preferably from 0.1 to 2.5 wt% enzymes; and

[0159] from 1 to 50 wt%, preferably from 5 to 40 wt% sophorolipid surfactant.

[0160] To form the alkaline soaking composition the alkaline soaking concentrate composition is suitably diluted with water. It is suitably diluted to provide a desired concentration based on the weight of the hide to be treated.

[0161] In some embodiments in which the alkaline soaking composition comprises a biosurfactant, the biosurfactant may be added to the already diluted alkaline soaking composition comprising the other ingredients, rather than being included in the alkaline soaking concentrate composition.In some embodiments the alkaline soaking composition may be prepared in situ by adding ingredients into a vessel comprising the animal hide.

[0162] Preferably the alkaline soaking composition used in step (a) comprises, by weight, based on the weight of the animal hide:

[0163] from 0.01 to 5 wt%, preferably from 0.1 to 0.5 wt% calcium salts;

[0164] from 0.01 to 1 wt%, preferably from 0.05 to 0.5 wt% urea;

[0165] from 0.001 to 0.5 wt%, preferably from 0.01 to 0.1 wt% surfactants;

[0166] from 0.001 to 0.1 wt% preferably from 0.005 to 0.05 wt% bactericide; and

[0167] from 0.0001 to 0.05 wt%, preferably from 0.001 to 0.005 wt% enzymes.

[0168] Preferably the alkaline soaking composition used in step (a) comprises, by weight, based on the weight of the animal hide:

[0169] from 0.01 to 1 wt%, preferably from 0.05 to 0.3 wt% calcium hydroxide;

[0170] from 0.01 to 1 wt%, preferably from 0.05 to 0.3 wt% calcium carbonate;

[0171] from 0.01 to 1 wt%, preferably from 0.05 to 0.5 wt% urea;

[0172] from 0.001 to 0.1 wt%, preferably from 0.005 to 0.06 wt% anionic surfactants; from 0.001 to 0.05 wt%, preferably from 0.002 to 0.015 wt% non-ionic surfactants; from 0.001 to 0.1 wt% preferably from 0.005 to 0.05 wt% bactericide; and

[0173] from 0.0001 to 0.05 wt%, preferably from 0.001 to 0.005 wt% enzymes.

[0174] In some embodiments the alkaline soaking composition used in step (a) comprises, by weight, based on the weight of the animal hide:

[0175] from 0.01 to 5 wt%, preferably from 0.1 to 0.5 wt% calcium salts;

[0176] from 0.01 to 1 wt%, preferably from 0.05 to 0.5 wt% urea;

[0177] from 0.001 to 0.5 wt%, preferably from 0.01 to 0.1 wt% surfactants;

[0178] from 0.001 to 0.1 wt% preferably from 0.005 to 0.05 wt% bactericide;

[0179] from 0.0001 to 0.05 wt%, preferably from 0.002 to 0.015 wt% enzymes; and from 0.005 to 0.5 wt%, preferably from 0.01 to 0.1 wt% biosurfacant.

[0180] Preferably the alkaline soaking composition used in step (a) comprises, by weight, based on the weight of the animal hide:

[0181] from 0.01 to 1 wt%, preferably from 0.05 to 0.3 wt% calcium hydroxide;

[0182] from 0.01 to 1 wt%, preferably from 0.05 to 0.3 wt% calcium carbonate;

[0183] from 0.01 to 1 wt%, preferably from 0.05 to 0.5 wt% urea;

[0184] from 0.001 to 0.1 wt%, preferably from 0.005 to 0.06 wt% anionic surfactants; from 0.001 to 0.05 wt%, preferably from 0.2 to 8 wt% non-ionic surfactants;

[0185] from 0.001 to 0.1 wt% preferably from 0.005 to 0.05 wt% bactericide;

[0186] from 0.0001 to 0.05 wt%, preferably from 0.001 to 0.005 wt% enzymes; andfrom .005 to 0.5 wt%, preferably from 0.01 to 0.15 wt% sophorolipid surfactant.

[0187] Step (b) of the method of the present invention is optional.

[0188] In some embodiments the method of the first aspect may include step (b) and in other embodiments the method may exclude step (b).

[0189] In some embodiments the method of the invention does not involve step (b). In such embodiments the pre-liming composition used in step (c) or the liming composition used in step (d) is added directly to the hide and alkaline soaking composition following step (a).

[0190] In such embodiments step (a) is suitably carried out for at least 10 minutes, preferably at least 20 minutes, more preferably at least 30 minutes prior to step (c) or step (d).

[0191] In preferred embodiments when the method does not include step (b), step (c) is included.

[0192] Step (b) is optional and step (c) is optional. Preferably the method of the first aspect of the present invention includes at least one of step (b) and step (c).

[0193] In some embodiments the method of the first aspect of the present invention includes step (b).

[0194] In some embodiments the method of the first aspect of the present invention includes step (c).

[0195] In some embodiments the method of the first aspect of the present invention includes step (b) and step (c).

[0196] When present step (b) of the method of the first aspect of the present invention involves removing the alkaline soaking composition from the animal hide. In some embodiments the step (b) may involve lifting the animal hide from the soaking composition. In some embodiments the alkaline soaking composition may be drained from the vessel comprising the animal hide. Suitable means for carrying out step (b) will be known to the person skilled in the art.

[0197] For the avoidance of doubt by removing alkaline soaking composition from the animal hide we mean that following step (a), step (b) involves ensuring that the animal hide is no longer immersed in the alkaline soaking composition. This may be achieved by removing the animal hide from a vessel containing the alkaline soaking composition or by removing the alkaline soaking composition from a vessel containing the animal hide. In step (b) the animal hide is removed from contact with the bulk alkaline soaking composition. However this does not mean that there is no residual alkaline soaking composition which remains on the animal hide.Step (b) suitably does not involve any rinsing or drying steps.

[0198] Step (c) of the method of the first aspect is an optional step.

[0199] In some embodiments the method of the first aspect may include step (c) and in other embodiments the method may exclude step (c).

[0200] In methods in which step (c) is not present, the alkaline soaking composition comprises a biosurfactant compound.

[0201] Step (c) involves contacting the animal hide with a pre-liming composition. The pre-liming composition comprises a biosurfactant compound. Preferably the pre-liming composition comprises a biosurfactant compound and water, more preferably a sophorolipid compound and water.

[0202] Preferably the pre-liming composition consists essentially of a biosurfactant compound and water, more preferably a sophorolipid compound and water.

[0203] The pre-liming composition used in step (c) preferably comprises at least 0.01 wt% biosurfactant compound based on the weight of the animal hide being treated, preferably at least 0.02 wt%, for example at least 0.05 wt%.

[0204] The pre-liming composition used in step (c) may comprise up to 1 wt% biosurfactant compound based on the weight of the animal hide being treated, preferably up to 0.5 wt%, for example up to 0.25 wt%.

[0205] The pre-liming composition used in step (c) preferably comprises from 0.01 to 2 wt% biosurfactant compound based on the weight of the animal hide being treated, preferably from 0.01 to 0.5 wt%, for example from 0.03 to 0.15 wt%.

[0206] The pre-liming composition used in step (c) preferably comprises at least 0.01 wt% sophorolipid compound based on the weight of the animal hide being treated, preferably at least 0.02 wt%, for example at least 0.05 wt%.

[0207] The pre-liming composition used in step (c) may comprise up to 1 wt% sophorolipid compound based on the weight of the animal hide being treated, preferably up to 0.5 wt%, for example up to 0.25 wt%.The pre-liming composition used in step (c) preferably comprises from 0.01 to 2 wt% sophorolipid compound based on the weight of the animal hide being treated, preferably from 0.01 to 0.5 wt%, for example from 0.03 to 0.15 wt%.

[0208] Preferably the pre-liming composition comprises less than 1 wt% of sulfide ions or a source thereof, preferably less than 0.1 wt%, more preferably less than 0.01 wt%.

[0209] Suitably the pre-liming composition does not comprise sulfide ions or a source thereof .

[0210] In this specification by the term sulfide ions or a source thereof we mean to refer to any compound that comprises sulfide ions, for example sodium sulfide or sodium hydrosulfide, or any compound which may generate or release sulfide ions under the conditions in which it is used.

[0211] Preferably the pre-liming composition comprises less than 1 wt% of sodium sulfide, preferably less than 0.1 wt%, more preferably less than 0.01 wt%.

[0212] Suitably the pre-liming composition does not comprise sodium sulfide.

[0213] The pre-liming composition may be prepared from a pre-liming concentrate composition. The pre-liming concentrate may consist essentially of the biosurfactant compound or it may comprise a concentrated solution of the biosurfactant in water.

[0214] Preferably the pre-liming concentrate composition is a concentrated aqueous solution comprising from 10 to 90 wt% biosurfactant compound, preferably from 20 to 80 wt%, suitably from 30 to 75 wt%, more preferably from 50 to 70 wt%, for example about 60 wt% biosurfactant compound, preferably a sophorolipid compound.

[0215] In some embodiments in which step (c) is present the alkaline soaking composition comprises a biosurfactant compound and the pre-liming composition comprises a biosurfactant compound.

[0216] In some embodiments in which step (c) is present the pre-liming composition comprises a biosurfactant compound and the alkaline soaking composition does not comprise a biosurfactant compound.

[0217] In the method of the present invention the alkaline soaking composition and / or the pre-liming composition comprises a biosurfactant compound.Any suitable biosurfactant compound may be used. Mixtures of two or more biosurfactant compounds may be used.

[0218] References herein to a biosurfactant or the biosurfactant compound include embodiments in which mixtures of two or more biosurfactant compounds are used. Thus the invention involves the use of one or more biosurfactant compounds.

[0219] By “biosurfactant” we mean to refer to a surfactant compound which is produced by a living cell and / or using naturally-derived substrates.

[0220] Biosurfactants include a polar (hydrophilic) moiety and a non-polar (hydrophobic) group. Typically, the hydrophilic group of a biosurfactant is a sugar (e.g., a mono-, di-, or polysaccharide) or a peptide, while the hydrophobic group is typically a fatty acid. Thus a large variety of biosurfactant molecules exist based on, for example, type of sugar, number of sugars, size of peptides, which amino acids are present in the peptides, fatty acid length, saturation of fatty acids, additional acetylation, additional functional groups, esterification, polarity and charge of the molecule.

[0221] Preferred biosurfactants for use herein include glycolipids (e.g., sophorolipids, rhamnolipids, cellobiose lipids, mannosylerythritol lipids and trehalose lipids), lipopeptides (e.g., surfactin, iturin, fengycin, arthrofactin and lichenysin), flavolipids, phospholipids (e.g., cardiolipins), fatty acid ester compounds, and high molecular weight polymers such as lipoproteins, lipopolysaccharide-protein complexes, and polysaccharide-protein-fatty acid complexes.

[0222] Preferred biosurfactants for use herein are sophorolipids.

[0223] The term sophorolipid as used herein includes acidic (linear) sophorolipids, lactonic sophorolipids, mono-acetylated sophorolipids, di-acetylated sophorolipids, esterified sophorolipids, sophorolipids with varying hydrophobic chain lengths, cationic and / or anionic sophorolipids with fatty acid-amino acid complexes attached, sophorolipid-metal complexes, sophorolipid salts, sophorolipid amino alcohols, sophorolipids with carbonyl groups removed from the aliphatic chain, and other derivatives thereof.

[0224] The term biosurfactant may refer to a surfactant that is produced by microorganisms, for example which may be a product of a fermentation process. Typically, a biosurfactant is generated as a metabolic product during bacterial, fungal or algal fermentation, and the metabolic product may be further derivatised. Thus, references herein to a biosurfactant refer to biosurfactants that are direct metabolic products of bacterial, fungal or algal fermentation, aswell as derivatives of the direct metabolic products. Similarly, references herein to a specific biosurfactant also referto derivatives of that biosurfactant unless otherwise stated.

[0225] The use of biosurfactants in the invention is advantageous, because biosurfactants are natural products, are generated in a sustainable way, are environmentally benign and typically have low toxicity.

[0226] Biosurfactants are typically classified in four categories as polymeric biosurfactants, lipopeptides (or also called proteo-lipids), phospholipids and glycolipids. The present invention may utilise a complex mixture of biosurfactants.

[0227] Biosurfactants may comprise one or more fatty acid and / or fatty alcohol residues. Suitably biosurfactants useful in the invention comprise one or more fatty acid residues.

[0228] The one or more fatty acid and / or fatty alcohol residues that may be present in the biosurfactants may be the same or different and may be derived from any suitable fatty acid and / or fatty alcohol, preferably from a naturally occurring fatty acid and / or fatty alcohol. Fatty acid residues are mostly derived from natural plant oils in the form of triglycerides. For example, biocatalysts may hydrolyse lipid esters in natural plant oils forming fatty acids and glycerol. Suitably, the fatty acid and / orfatty alcohol residues may comprise a branched or unbranched, saturated or unsaturated, hydrocarbyl group.

[0229] The fatty acid and / or fatty alcohol residues that may be present in the biosurfactants may comprise from 4 to 50 carbon atoms, for example from 6 to 30 carbon atoms, preferably from 8 to 24 carbon atoms, more preferably from 12 to 22, or from 14 to 20 or from 16 to 18 carbon atoms. Preferred biosurfactants may therefore comprise residues of fatty acids derived from oleic acid, hydroxy substituted oleic acid (such as ricinoleic acid), palmitic acid and vegetable oils (such as sunflower, corn, soya, safflower oil and rapeseed oil) or mixtures thereof.

[0230] Any suitable biosurfactants may be used. Suitable biosurfactants include one or more of a glycolipid, a lipopeptide, a phospholipid and a polymeric biosurfactant (including mixtures thereof). For example, the invention may use a glycolipid and a lipopeptide, a glycolipid, a lipopeptide and a phospholipid, or two different glycolipids and so on.

[0231] The biosurfactants useful herein may have any suitable molecular weight, such as a molecular weight of from 200 to 3000 g mol-1 , for example from 250 to 2000 g mol-1 , such as from 500 to 1500 g mol-1.Preferred biosurfactants are glycolipids. Glycolipids comprise one or more carbohydrate residues in addition to the one or more fatty acid and / or fatty alcohol residues. The carbohydrate and fatty acid / fatty alcohol residues are joined either by means of a linker group or a direct bond, for example via an ester, amide orglycosidic bond.

[0232] Suitable glycolipids may comprise one or more carbohydrate residues selected from rhamnose, trehalose, sophorose, mannose, galactose, glucose, cellobiose, glucosamine, sulfoquinovose, fructose, xylose, sucrose, lactose, maltose, sorbitol, erythritol and / or mannitol residues. For example, the one or more carbohydrate residues may be selected from rhamnose, trehalose, sophorose, mannose, erythritol, galactose, cellobiose and / or glucose residues. Preferably, the one or more carbohydrate residues may be selected from rhamnose, trehalose, sophorose, mannose and / or erythritol residues. More preferably, the one or more carbohydrate residues may be selected from sophorose and / or rhamnose residues. Most preferably, the one or more carbohydrate residues may be sophorose residues.

[0233] Suitable glycolipids may be selected from one or more of a rhamnolipid, a trehalolipid, a sophorolipid, a mannosylerythritol lipid, a glycolipid produced by Meyerozama guilliermondii, Saccharomyces cerevisiae, Candida utilis, Candida bombicola and / or Marinobacter hydrocarbonoclasticus.

[0234] For example, suitable glycolipids may be selected from one or more of a rhamnolipid, a trehalolipid, a sophorolipid and a mannosylerythritol lipid. Preferred glycolipids are sophorolipids.

[0235] Suitable biosurfactants include one or more of a rhamnolipid, a trehalolipid, a sophorolipid and a mannosylerythritol lipid. Preferred biosurfactants are one or more of a rhamnolipid and a sophorolipid. Most preferred biosurfactants are one or more sophorolipids.

[0236] Rhamnolipids comprise a rhamnose residue. Examples of suitable rhamnolipids may include those produced by species of Pseudomonas, Lysinibacillus and / or Serratia, for example those produced by Pseudomonas aeruginosa, Pseudomonas cepacia, Lysinibacillus sphaericus and / or Serratia rubidaea.

[0237] Trehalolipids comprise a trehalose residue. Examples of suitable trehalolipids may include those produced by species of Nocardia, Rhodococcus, Starmerella, Arthrobacter, Corynebacterium and / or Candida, for example those produced by Rhodococcus erythropolis, Nocardia farcinica and / or Candida bombicola (also known as Starmerella bombicola).

[0238] Mannosylerythritol lipids comprise a mannose residue and an erythritol residue, preferably joined by an ether bond. Examples of suitable mannosylerythritol lipids may include thoseproduced by species of Pseudozyma and / or Ustilago, for example Pseudozyma aphidis or Pseudozyma antarctica.

[0239] Sophorolipids comprise a sophorose residue. Examples of suitable sophorolipids may include those produced by species of Candida, Starmerella and / or Cutaneotrichosporon, for example those produced by Candida sphaerica, Starmerella bombicola and / or Cutaneotrichosporon mucoides. Suitable sophorolipids may exist in the “lactonic” form wherein a fatty acid residue is bonded separately to each ring of the sophorose residue to form a lactonic macrocycle. When the fatty acid residue is not bonded to a sophorose residue this may be known as the “acidic” form. Suitable sophorolipids may have a molar ratio of acidic to lactonic form in the range 99:1 to 1 :99, for example in the range 50:50 to 60:40 or in the range 50:50 to 40:60. Suitable sophorolipids may have a molar ratio of acidic to lactonic form of 70:30 or of 30:70.

[0240] Suitably, greater than 60%, for example greater than 70%, preferably greater than 80%, more preferably greater than 90%, of the sophorolipids may comprise an unsaturated fatty acid and / or fatty alcohol residue.

[0241] Suitable biosurfactants may be those produced by species of Pseudomonas, Lysinibacillus, Serratia, Nocardia, Rhodococcus, Candida, Starmerella, Cutaneotrichosporon, Pseudozyma, Meyerozyma, Saccharomyces, Marinobacter, Bacillus, Lactobacillus Virgibacillus, Halomonas, Thiobacillus, Acidithiobacillus, Klebsiella, Alcanivorax, Arthrobacter, Rhodotorula, Tsukamurella, Ustilago, Sphingomonas, Mycobacterium, Streptomyces, Gluconobacter, Aspergillus and / or Acinetobacter.

[0242] The biosurfactants that are produced by a specific micro-organism may vary depending on the feedstock used and other variables in the growth conditions (e.g. temperature, pH, agitation and dissolved oxygen). Preferably, feedstocks comprise carbohydrates and / or lipids. Preferred lipid feedstocks are in the form of triglycerides. The feedstocks may comprise agricultural and / or industrial waste, for example vegetable oils, animal or vegetable fats, cooking oil waste, whey, glycerol, and / or combinations thereof. Biosurfactants suitable for the invention are preferably produced by micro-organisms from feedstock comprising carbohydrate and one or more lipids. More preferably, they are produced from feedstock comprising carbohydrate and one or more of vegetable oils (for example rapeseed, palm, sunflower, corn, soya and / or safflower oils), animal fats and vegetable fats.

[0243] Suitable biosurfactants may be recovered from the fermentation broth before use by known recovery methods. For example, the biosurfactants may be recovered by precipitation, filtration (including ultrafiltration), adsorption to solid supports, centrifugation, chromatography (e.g. ion-exchange chromatography), foam fractionation, liquid-liquid extraction, and / or gravity separation (decanting).

[0244] Suitable biosurfactants may be used as crude extracts, or they may undergo further purification and / or derivatisation before use.

[0245] Where biosurfactants are further purified, this may involve one or more purification techniques available to the skilled person, for example chromatographic techniques, ultrafiltration or washing with a suitable solvent (which solvent may be polar or non-polar).

[0246] Where biosurfactants are further derivatised, this may comprise derivatisation of the fatty acid and / or fatty alcohol residues. Where the fatty acid or fatty alcohol residue has an unsaturated alkyl group, suitable methods for derivatisation of the fatty acid or fatty alcohol residue include mild reductive, strong reductive or oxidative ozonolysis with sodium periodate (resulting in a dialdehyde, diol or diacid respectively); dihydroxylation, for example with OsC ; epoxidation, for example with m-chloroperoxybenzoic acid; reduction, for example with H2 on a Pd / C catalyst; ring opening metathesis; treatment with HBr; or mono-hydroxylation, for example by hydroboration with an oxidative work-up.

[0247] Where the biosurfactant is a glycolipid, the carbohydrate may be derivatised at the alcohol groups by esterification (e.g. with an anhydride), carboxymethylation (e.g. with an a-chloro acid), oxidation (to e.g. aldehyde or carboxylic acid), reaction with a non-ionic epoxide (e.g. ethylene oxide, propylene oxide), reaction with a cationic epoxide (e.g. glycidyltrimethyl ammonium chloride). The carbohydrate may be further derivatised by oxidative ring opening (e.g. with a periodate) resulting in a dialdehyde.

[0248] Derivatives of biosurfactants comprising aldehyde groups may be further derivatised, for example to alcohols, carboxylic acids, esters, amides, imines and / or amines. Derivatives of biosurfactants comprising carboxylic acid groups may be further derivatised, for example to esters and / or amides. Derivatives of biosurfactants comprising 1 ,2-diol groups may be further derivatised, for example by C-C bond cleavage with periodate or peroxide, or reaction with an aldehyde.

[0249] Step (d) of the method of the second aspect of the present invention involves contacting the animal hide with a liming composition comprising sulfide ions or a source thereof .

[0250] The liming composition may comprise one or more further ingredients. Preferably the liming composition comprises one or more alkali metal or alkaline earth metal salts.Suitable salts include sodium, potassium, magnesium and calcium salts of carbonate, sulfate, hydroxide, nitrate, phosphate and halide (for example chloride or bromide) anions.

[0251] Preferred salts are calcium salts. Preferred calcium salts include calcium carbonate, calcium hydroxide and mixtures thereof.

[0252] In some embodiments the liming composition comprises calcium hydroxide.

[0253] In some embodiments the liming composition comprises calcium carbonate.

[0254] In some embodiments the liming composition comprises calcium hydroxide and calcium carbonate.

[0255] Preferably the liming composition comprises urea.

[0256] In some embodiments the liming composition comprises a sugar. It may comprise a mixture of two or more sugars. Suitable sugars are known to the person skilled in the art. Suitable sugars include dextrose, fructose, galactose, glucose, lactose, maltose and sucrose.

[0257] Preferred sugars include sucrose, glucose, dextrose and mixtures thereof. Sucrose is especially preferred.

[0258] In some embodiments the liming composition comprises a pH modifiers. Suitable pH modifiers include polycarboxylic acids, for example citric acid and oxalic acid.

[0259] In some embodiments the liming composition has a pH of from 9 to 12.

[0260] In some embodiments the liming composition comprises a filler, carrier or fluidising agent, for example silica.

[0261] The liming composition is added after the addition of the alkaline soaking composition and the optional pre-liming composition.

[0262] Preferably the liming composition which is added in step (d) comprises less than 1 wt% of a biosurfactant compound, preferably less than 0.1 wt%, more preferably less than 0.01 wt%.

[0263] Preferably the liming composition does not comprise a biosurfactant compound.Although the liming composition preferably does not comprise a biosurfactant compound there may be some residual biosurfactant compound present on the hide from the alkaline soaking composition and / or the pre-liming composition. This is not excluded in the present invention but it is important that the hide is contacted with the biosurfactant compound prior to contact with the liming composition comprising sulfide ions or a source thereof.

[0264] In embodiments in which step (c) is present step (d) may involve adding components of the liming composition to the pre-liming composition. However step (c) is preferably carried out for at least 10 minutes, preferably at least 30 minutes, more preferably at least 60 minutes prior to step (d). In preferred embodiments step (c) is carried out for at least 2 hours prior to step (d).

[0265] The liming composition may be prepared from a liming concentrate composition or a plurality of liming precursor compositions.

[0266] For example the liming composition may be prepared from a first liming precursor composition comprising sulfide ions or a source thereof and a second liming precursor composition comprising at least one alkali metal or alkaline earth metal salt, preferably at least one calcium salt.

[0267] Preferably the second liming precursor composition comprises at least one calcium salt and urea.

[0268] Preferably the second liming precursor composition comprises at least one calcium salt, urea and sugar.

[0269] Preferably the second liming precursor composition comprises calcium carbonate.

[0270] Preferably the second liming precursor composition comprises calcium carbonate, urea, sugar and calcium hydroxide.

[0271] In some embodiments the liming composition may be prepared from a first liming precursor composition comprising sulfide ions or a source thereof; a second liming precursor composition comprising at least one alkali metal or alkaline earth metal salt, urea and sugar; and a third liming composition comprising an alkali metal or alkaline earth metal hydroxide.

[0272] Preferably the first liming precursor composition is provided as a solid.

[0273] Preferably the second liming precursor composition is provided as a solid.In some embodiments a third liming composition may be provided comprising calcium hydroxide. This is suitably provided as a solid.

[0274] The one or more liming precursor compositions may be diluted with water and / or the pre-liming composition to form the liming composition.

[0275] The liming composition used in step (d) preferably comprises at least 0.5 wt% alkali metal or alkaline earth metal salts, based on the weight of the animal hide being treated, preferably at least 1 wt%, preferably at least 2.5 wt%.

[0276] The liming composition used in step (d) preferably comprises up to 30 wt% alkali metal or alkaline earth metal salts, based on the weight of the animal hide being treated, up to 20 wt%, preferably up to 10 wt%.

[0277] Preferably the liming composition used in step (d) comprises from 0.1 to 25 wt% alkali metal or alkaline earth metal salts, based on the weight of the animal hide being treated, preferably from 1 to 15 wt%, preferably from 2 to 10 wt%.

[0278] The liming composition used in step (d) preferably comprises at least 0.5 wt% calcium salts, based on the weight of the animal hide being treated, preferably at least 1 wt%, preferably at least 2.5 wt%.

[0279] The liming composition used in step (d) preferably comprises up to 30 wt% calcium salts, based on the weight of the animal hide being treated, up to 20 wt%, preferably up to 10 wt%.

[0280] Preferably the liming composition used in step (d) comprises from 0.1 to 25 wt% calcium salts, based on the weight of the animal hide being treated, preferably from 1 to 15 wt%, preferably from 2 to 10 wt%.

[0281] The liming composition used in step (d) preferably comprises at least 0.5 wt% calcium hydroxide, based on the weight of the animal hide being treated, preferably at least 1 wt%, preferably at least 2.5 wt%.

[0282] The liming composition used in step (d) preferably comprises up to 30 wt% calcium hydroxide, based on the weight of the animal hide being treated, up to 20 wt%, preferably up to 10 wt%.

[0283] Preferably the liming composition used in step (d) comprises from 0.1 to 25 wt% calcium hydroxide, based on the weight of the animal hide being treated, preferably from 1 to 15 wt%, preferably from 2 to 10 wt%.The liming composition used in step (d) preferably comprises at least 0.01 wt% calcium carbonate, based on the weight of the animal hide being treated, preferably at least 0.1 wt%, preferably at least 0.2 wt%.

[0284] The liming composition used in step (d) preferably comprises up to 10 wt% calcium carbonate, based on the weight of the animal hide being treated, up to 5 wt%, preferably up to 1 wt%.

[0285] Preferably the liming composition used in step (d) comprises from 0.01 to 2.5 wt% calcium carbonate, based on the weight of the animal hide being treated, preferably from 0.05 to 1 wt%, preferably from 0.1 to 0.6 wt%.

[0286] The liming composition used in step (d) preferably comprises at least 0.01 wt% urea, based on the weight of the animal hide being treated, preferably at least 0.05 wt%, preferably at least 0.1 wt%.

[0287] The liming composition used in step (d) preferably comprises up to 5 wt% urea, based on the weight of the animal hide being treated, up to 2 wt%, preferably up to 0.5 wt%.

[0288] Preferably the liming composition used in step (d) comprises from 0.01 to 5 wt% urea, based on the weight of the animal hide being treated, preferably from 0.05 to 0.8 wt%, preferably from 0.1 to 0.3 wt%.

[0289] The liming composition used in step (d) preferably comprises at least 0.01 wt% sugars based on the weight of the animal hide being treated, preferably at least 0.02 wt%, preferably at least 0.05 wt%.

[0290] The liming composition used in step (d) preferably comprises up to 5 wt% sugars, based on the weight of the animal hide being treated, up to 1 wt%, preferably up to 0.2 wt%.

[0291] Preferably the liming composition used in step (d) comprises from 0.01 to 5 wt% sugars, based on the weight of the animal hide being treated, preferably from 0.02 to 1 wt%, preferably from 0.05 to 0.1 wt%.

[0292] A particular advantage of the present invention is that it allows a lower concentration of sulfide ions or a source thereof to be used in the liming step.The liming composition used in step (d) preferably comprises less than 4 wt% of sulfide ions or a source thereof, based on the weight of the animal hide being treated, preferably less than 3 wt%, preferably less than 2 wt%.

[0293] Preferably the liming composition used in step (d) comprises from 0.1 to 2 wt% sulfide ions or a source thereof, based on the weight of the animal hide being treated, preferably from 0.2 to 1.5 wt%, preferably from 0.5 to 1 wt%.

[0294] In some embodiments the first aspect of the present invention provides a method of treating an animal hide, the method comprising steps of:

[0295] (a) soaking the animal hide in an alkaline soaking composition;

[0296] (b) removing the alkaline soaking composition from the animal hide;

[0297] (c) contacting the animal hide with a pre-liming composition; and

[0298] (d) contacting the animal hide with a liming composition comprising sulfide ions or a source thereof;

[0299] wherein the pre-liming composition comprises a biosurfactant compound.

[0300] In some embodiments the first aspect of the present invention provides a method of treating an animal hide, the method comprising steps of:

[0301] (a) soaking the animal hide in an alkaline soaking composition;

[0302] (b) removing the alkaline soaking composition from the animal hide;

[0303] (c) contacting the animal hide with a pre-liming composition; and

[0304] (d) contacting the animal hide with a liming composition comprising sulfide ions or a source thereof;

[0305] wherein the alkaline soaking composition and the pre-liming composition each comprises a biosurfactant compound.

[0306] According to a fourth aspect of the present invention there is provided a kit for treating an animal hide, the kit comprising:

[0307] (i) a liming concentrate composition or a plurality of liming precursor compositions comprising sulfide ions or a source thereof; and one or more of:

[0308] (ii) an alkaline soaking concentrate composition; and

[0309] (iii) a pre-liming concentrate composition;

[0310] wherein the alkaline soaking concentrate composition and / or the pre-liming concentrate composition comprises a biosurfactant compound.According to a fifth aspect of the present invention there is provided a system for treating an animal hide, the system comprising:

[0311] (x) a liming composition comprising sulfide ions or a source thereof; and one or more of:

[0312] (y) an alkaline soaking composition; and

[0313] (z) a pre-liming composition;

[0314] wherein the alkaline soaking composition and / or the pre-liming composition comprises a biosurfactant compound.

[0315] The system of the fifth aspect may be prepared using the kit of the fifth aspect. In some embodiments the kit of the fourth aspect may further comprise instructions for preparing a system of the fifth aspect.

[0316] According to a sixth aspect of the present invention there is provided the use of a biosurfactant to reduce the concentration of sulfide ions or a source thereof needed to achieve depilation in an animal hide treatment process.

[0317] Preferred features of the fourth, fifth and sixth aspects of the invention are as described in relation to the first, second and third aspects. Further preferred features of the invention will now be described. Any feature of any aspect of the invention may apply to any other aspect.

[0318] In step (a) of the method of the first aspect of the present invention the alkaline soaking composition is suitably contacted with the animal hide at ambient temperature.

[0319] Suitably the animal hide is agitated within the alkaline soaking composition, for example by rotation, during step (a).

[0320] Step (a) is suitably carried out for at least 10 minutes, preferably at least 30 minutes, more preferably at least 60 minutes.

[0321] Step (a) may be carried out for at least 2 hours, suitably at least 4 hours, for example from 6 to 12 hours.

[0322] In step (b) of the method of the first aspect of the present invention the alkaline soaking composition is removed from the animal hide. This may involve removing the animal hide from the alkaline soaking composition or draining the alkaline soaking composition from a tank containing the hide. Suitably no further drying or washing steps are involved.When present, in step (c) of the method of the first aspect of the present invention the pre-liming composition is suitably contacted with the animal hide at ambient temperature.

[0323] Suitably the animal hide is agitated within the pre-liming composition, for example by rotation, during step (c).

[0324] Step (c) is suitably carried out for at least 10 minutes, preferably at least 20 minutes, more preferably at least 30 minutes.

[0325] Step (c) may be carried out for at least 60 minutes, for example from 1 to 12, preferably 1 to 4 hours.

[0326] In step (d) of the method of the first aspect of the present invention the liming composition is suitably contacted with the animal hide at ambient temperature.

[0327] Suitably the animal hide is agitated within the liming composition, for example by rotation, during step (d).

[0328] Step (d) is suitably carried out for at least 10 minutes, preferably at least 30 minutes, more preferably at least 60 minutes.

[0329] Step (d) may be carried out for at least 2 hours, suitably at least 6 hours, for example from 8 to 18 hours.

[0330] Preferably in the method of the first aspect, the concentration of sulfide ions or a source thereof present in the liming composition is lower than would be needed to achieve an equivalent level of depilation if the biosurfactant compound was not present in the alkaline soaking composition and / or the pre-liming composition.

[0331] Preferably the present invention reduces the amount of sulfide ions or a source thereof needed to achieve an equivalent level of depilation by at least 5%, preferably by at least 10%, suitably by at least 20%.

[0332] In some embodiments the present invention may reduce the amount of sulfide ions or a source thereof needed to achieve an equivalent level of depilation by more than 30%, for example more than 40% or more than 50%.

[0333] By an equivalent level of depilation we mean to refer to approximately the same level of hair and keratin removal on the same type of animal hide under otherwise identical conditions except forinclusion of the biosurfactant. The level of hair removal can be visually assessed by the skilled person.

[0334] Preferably the present invention can be used to remove at least 60% of hair and other keratinous materials from the surface of an animal hide, preferably at least 70%, more preferably at least 80%, for example at least 90% or at least 95%.

[0335] The present invention provides a reduction in the amount of sulfide ions or a source thereof used in a leather tanning process. This offers a number of advantages. The method of the present invention has an improved safety profile as lower concentrations of hydrogen sulfide gas are likely to be released. The waste products from the method of the present invention are easier to process. In addition a higher quality leather product which is less prone to fungal contamination is provided.

[0336] In addition to the aforementioned advantages, the present inventors have additionally found that animal hides treated according to the method of the present invention have improved softness and whiteness.

[0337] According to a seventh aspect of the present invention there is provided the use of a biosurfactant as a bleaching agent in an animal hide treatment process.

[0338] According to an eighth aspect of the present invention there is provided the use of a biosurfactant as a softening agent in an animal hide treatment process.

[0339] The animal hide treatment in the seventh and eighth aspects is preferably a method of the first aspect. Preferred features of the seventh and eighth aspects are as defined in relation to the first, second and third aspects.

[0340] In a preferred embodiment the seventh aspect involves the use of biosurfactant as a bleaching agent in an animal hide treatment process; wherein the animal hide treatment involves the steps of:

[0341] (a) soaking the animal hide in an alkaline soaking composition;

[0342] (b) contacting the animal hide with a pre-liming composition comprising a biosurfactant compound; and

[0343] (c) contacting the animal hide with a liming composition comprising sulfide ions or a source thereof.By use of a biosurfactant as a bleaching agent we mean that the animal hide treated according to the invention has improved whiteness compared with an equivalent process in which the biosurfactant is not present.

[0344] Whiteness may be assessed visually or may be measured by means known in the art, for example by use of a colorimeter.

[0345] In a preferred embodiment the eighth aspect involves the use of biosurfactant as a softening agent in an animal hide treatment process; wherein the animal hide treatment involves the steps of:

[0346] (a) soaking the animal hide in an alkaline soaking composition;

[0347] (b) contacting the animal hide with a pre-liming composition comprising a biosurfactant compound; and

[0348] (c) contacting the animal hide with a liming composition comprising sulfide ions or a source thereof.

[0349] Softness is suitably assessed by touch and comparison to other hides.

[0350] The invention will now be further defined with reference to the following non-limiting examples.

[0351] Examples 1 to 15

[0352] Bovine hides that were previously preserved by spreading coarse salt on top of them, were first subjected to a salt removal step by washing them with water. This washing step was either a thorough wash (soaking the preserved hide in water under stirring for 20 mins) or a brief wash (rinsing the preserved hide for 1 minute under a faucet).

[0353] Thorough washing is denoted as (T) and brief washing is denoted as (B) in Table 1.

[0354] Treatment method 1 - Hide treatment with no pre-liming step

[0355] A washed hide obtained after the salt removal step was placed in a drum containing an alkaline soaking composition. The alkaline soaking composition was an aqueous composition and was used in a total weight amount of 80% based on the weight of the hide. Table 1 details the amounts of each component present in that composition as a percentage by weight based on the weight of the hide.

[0356] The hide was soaked in the alkaline soaking composition for 8 hours under rotation at a speed of 5 rpm. The alkaline soaking composition was then drained, and a liming composition was added to the drum containing the hide. The liming composition is an aqueous composition andwas added to the drum in a total weight amount of 40% based on the weight of the hide. Table 1 details the amounts of each component present in that composition as a percentage by weight based on the weight of the hide.

[0357] The hide was soaked in the liming composition for 12 hours under rotation at a speed of 5 rpm. The liming composition was then drained from the drum and the hide was visually assessed to determine the degree of depilation.

[0358] Treatment method 2 - Hide treatment with pre-liming step

[0359] A washed hide obtained from the salt removal step was treated with an alkaline soaking composition under the same conditions described in Treatment method 1. After the alkaline soaking composition was drained, a pre-liming composition was added to the drum in a total weight amount of 40% based on the weight of the hide. The components of the pre-liming composition are defined in table 1 in amounts based on the weight of the hide.

[0360] The hide was soaked in the pre-liming composition for 2 hours at a speed of 5 rpm. After this period a liming composition was formed in situ, without removal of the pre-liming composition, by adding the liming ingredients to the pre-liming composition containing the hide. Table 1 details the amounts of each component present in the liming composition as a percentage by weight based on the weight of the hide.

[0361] The hide was soaked in the liming composition for 12 hours under rotation at a speed of 5 rpm. The liming composition was then drained from the drum and the hide was visually assessed to determine the degree of depilation.

[0362] Bovine hides of Examples 1 , 2, 5 to 11 , 13 and 14 were treated according to Treatment method 1 and those of Examples 3, 4, 12 and 15 were treated according to Treatment method 2.

[0363] Table 1 details the components and concentrations of the soaking, pre-liming (when used), and liming compositions used in the treatment methods 1 and 2 described above. The amounts listed represent the amount of active component in the composition as a percentage by weight based on the weight of the bovine hide treated.

[0364] Examples 3 to 5, 7, 12, 14 and 15 are inventive. Examples 1 , 2, 6, 8 to 11 and 13 are comparative.Table 1

[0365]

[0366]

[0367]

[0368]

[0369] Example 16

[0370] 16,000 kg (500 units) of fresh, non-preserved hides (no salt spread on the surface of the hide) were loaded into a production wooden drum. The drum was then loaded with the components listed below to form an alkaline soaking composition. The amounts listed represent the amount of each component in the composition as a percentage by weight based on the weight of the bovine hide treated.

[0371]

[0372] The wetting agent contained 20-30% sucrose, 5-10% sodium mercaptoacetate, and 3-5% NaOH

[0373] The loaded drum was then agitated for 1 hour and then agitation was stopped.

[0374] 0.06 wt% of sophorolipids based on the weight of the hide was added to the drum to form a preliming composition, and agitation was restarted and maintained for one hour.

[0375] The drum was then loaded with 0.625 wt% of calcium hydroxide and 1 .75 wt% of a commercial depilation agent, based on the weight of the bovine hide treated.

[0376] The commercial depilation agent contained 5.41 wt% of a sulfide species and 0.5 to 1 ppm protease.

[0377] Agitation was restarted and continued for 4 hours before stopping again.

[0378] Following addition of 2.97 wt% of calcium hydroxide based on the weight of the hide agitation was restarted and continued for another hour before stopping once more.

[0379] 150 wt% of water, 0.05 wt% ethoxylated fatty alcohol and 0.03 wt% dodecyl sulfonate was added and then agitation was recommenced and continued for 12 hours.

[0380] After agitation was stopped the final pH was from 12.5 to 13.5. The hides were removed from the drum and visually inspected.A comparative test was conducted without addition of sophorolipids.

[0381] The use of the sophorolipids was found to provide a hide which was visibly whiter and softer to the touch.

Claims

Claims1. A method of treating an animal hide, the method comprising steps of:(a) soaking the animal hide in an alkaline soaking composition;(b) optionally removing the alkaline soaking composition from the animal hide;(c) optionally contacting the animal hide with a pre-liming composition; and(d) contacting the animal hide with a liming composition comprising sulfide ions or a source thereof;wherein the alkaline soaking composition and / or the pre-liming composition comprises a biosurfactant compound.

2. An alkaline soaking composition comprising one or more components selected from enzymes, surfactants, amino compounds, phosphate compounds, alkali metal or alkaline earth metal salts, bactericides and mixtures thereof; and a biosurfactant compound.

3. An alkaline soaking concentrate composition comprising one or more components selected from enzymes, surfactants, amino compounds, phosphate compounds, alkali or alkaline earth metal salts, bactericides and mixtures thereof; and a biosurfactant compound.

4. A kit for treating an animal hide, the kit comprising:(i) a liming concentrate composition comprising sulfide ions or a source thereof; and one or more of:(ii) an alkaline soaking concentrate composition; and(iii) a pre-liming concentrate composition;wherein the alkaline soaking concentrate composition and / or the pre-liming concentrate composition comprises a biosurfactant compound.

5. A system for treating an animal hide, the system comprising:(x) a liming composition comprising sulfide ions or a source thereof; and one or more of:(y) an alkaline soaking composition; and(z) a pre-liming composition;wherein the alkaline soaking composition and / or the pre-liming composition comprises a biosurfactant compound.

6. The use of a biosurfactant compound to reduce the concentration of sulfide ions or a source thereof needed to achieve depilation in an animal hide treatment process.

7. The use of a biosurfactant as a bleaching agent in an animal hide treatment process.

8. The use of a biosurfactant as a softening agent in an animal hide treatment process.

9. A method, kit or system according to any of claims 1 , 4 or 5 wherein the alkaline soaking composition or the alkaline soaking concentrate composition comprises one or more components selected from enzymes, surfactants, amino compounds, phosphate compounds, calcium salts bactericides and mixtures thereof; and a biosurfactant compound.

10. A method according to claim 1 which includes step (b).

11. A method according to claim 1 which includes step (c).

12. A method according to claim 11 wherein the alkaline soaking composition does not comprise a biosurfactant compound.

13. A method according to claim 11 wherein the alkaline soaking composition comprises a biosurfactant compound.

14. A method according to claim 1 which does not include step (c).

15. A method according to any of claims 1 or 9 to 14 wherein the concentration of sulfide ions or a source thereof present in the liming composition is lower than would be needed to achieve an equivalent level of depilation if the biosurfactant compound was not present in the alkaline soaking composition and / or the pre-liming composition.

16. A method according to any of claims 1 or 9 to 15 wherein the liming composition preferably comprises sulfide ions or a source thereof in an amount of less than 1.25% by weight based on the weight of the animal hide.

17. A method according to any of claims 1 or 9 to 16 wherein step (d) does not involve the addition of a biosurfactant compound.

18. A method, composition, kit, system or use according to any preceding claim wherein the biosurfactant compound is selected from one or more of a rhamnolipid, a trehalolipid, a sophorolipid and a mannosylerythritol lipid.

19. A method, composition, kit, system or use according to any preceding claim wherein the biosurfactant compound is a sophorolipid compound.

20. A method, composition, kit, system or use according to any preceding claim which reduces the amount of sulfide ions or a source thereof needed to achieve an acceptable level of depilation by at least 20%.

21. An alkaline soaking composition according to claim 2 for use in step (a) of the method of any of claims 1 or 9 to 17 which comprises, based on the weight of the animal hide being treated:from 0.01 to 5 wt%, preferably from 0.1 to 0.5 wt% calcium salts;from 0.01 to 1 wt%, preferably from 0.05 to 0.5 wt% urea;from 0.001 to 0.5 wt%, preferably from 0.01 to 0.1 wt% surfactants;from 0.001 to 0.1 wt% preferably from 0.005 to 0.05 wt% bactericide;from 0.0001 to 0.05 wt%, preferably from 0.002 to 0.015 wt% enzymes; and from 0.005 to 0.5 wt%, preferably from 0.01 to 0.1 wt% biosurfacant.

22. An alkaline soaking composition according to claim 2 or claim 21 for use in step (a) which comprises, based on the weight of the animal hide being treated:from 0.01 to 1 wt%, preferably from 0.05 to 0.3 wt% calcium hydroxide;from 0.01 to 1 wt%, preferably from 0.05 to 0.3 wt% calcium carbonate;from 0.01 to 1 wt%, preferably from 0.05 to 0.5 wt% urea;from 0.001 to 0.1 wt%, preferably from 0.005 to 0.06 wt% anionic surfactants; from 0.001 to 0.05 wt%, preferably from 0.2 to 8 wt% non-ionic surfactants;from 0.001 to 0.1 wt% preferably from 0.005 to 0.05 wt% bactericide;from 0.0001 to 0.05 wt%, preferably from 0.001 to 0.005 wt% enzymes; and from .005 to 0.5 wt%, preferably from 0.01 to 0.15 wt% sophorolipid surfactant.

23. An alkaline soaking concentrate composition according to claim 3 comprising:from 30 to 90 wt%, preferably from 40 to 80 wt% calcium salts;from 10 to 50 wt%, preferably from 20 to 40 wt% urea;from 0.1 to 25 wt%, preferably from 0.5 to 12 wt% surfactants;from 0.1 to 20 wt% preferably from 0.5 to 10 wt% bactericide;from 0.01 to 10 wt%, preferably from 0.1 to 2.5 wt% enzymes; andfrom 1 to 50 wt%, preferably from 5 to 40 wt% biosurfacant.

24. An alkaline soaking concentrate composition according to claim 3 or claim 23 comprising:from 10 to 50 wt%, preferably from 20 to 40 wt% calcium hydroxide;from 10 to 50 wt%, preferably from 20 to 40 wt% calcium carbonate;from 30 to 90 wt%, preferably from 40 to 80 wt% urea;from 0.1 to 20 wt%, preferably from 0.5 to 10 wt% anionic surfactants;from 0.1 to 15 wt%, preferably from 0.2 to 8 wt% non-ionic surfactants;from 0.1 to 20 wt% preferably from 0.5 to 10 wt% bactericide;from 0.01 to 10 wt%, preferably from 0.1 to 2.5 wt% enzymes; and from 1 to 50 wt%, preferably from 5 to 40 wt% sophorolipid surfactant.

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