A process for extracting water-soluble cocoa pigment for textile dyeing

Abstract

The invention discloses an extraction process of water-soluble cocoa pigment for textile dyeing, belongs to the field of extraction technology, and comprises seven steps of pretreatment, high-temperature baking, continuous countercurrent extraction, filtration and impurity removal, chemical modification treatment, nanofiltration desalination concentration, and spray drying. The process can extract water-soluble cocoa pigment from cocoa bean shells quickly, with low energy consumption, low cost and pollution-free. The obtained cocoa pigment has excellent color fastness and dyeing rate in textile dyeing application, and has stable performance.

Description

Technical Field

[0001] The invention belongs to the technical field of extraction, and in particular relates to an extraction process of water-soluble cocoa pigment for textile dyeing. Background Art

[0002] Cocoa color is a natural food coloring, chocolate-colored powder, soluble in water, odorless, slightly bitter, easy to absorb moisture, and easily soluble in water and dilute ethanol solution. Its color deepens with the increase of pH value, but the hue is not affected and is relatively stable; it is also heat-resistant, light-resistant, and oxidation-resistant. Cocoa color has good dyeing properties for protein and starch, especially for starch, which is much better than caramel color, and rarely changes during processing and storage. Only when pH <4, precipitation will occur. Its main coloring component is polyflavonoid glycoside.

[0003] Cocoa pigment is a natural edible pigment extracted from the seeds, cocoa beans and skin of the cocoa tree fruit. It has the color of cocoa beans and is an indispensable pigment for making many foods. There are many biological extraction technologies, such as CN201510319057.2, which discloses a method for extracting cocoa pigment from cocoa beans. The cocoa bean peel is dried and crushed, washed with citric acid and then leached with sodium carbonate solution. The extract is washed with sodium carbonate solution on the column, and the washing column liquid is filtered and concentrated and dried to obtain cocoa pigment. Because a large amount of acid solution and alkaline solution are used in the process, and the traditional extraction tank is used for extraction and the concentration tank is used for concentration, the process has large environmental pollution and high energy consumption; and the product is to collect 50% sodium carbonate washing column liquid, concentrate and dry, resulting in a large amount of sodium carbonate in the cocoa pigment finished product, and there is no desalination process, which seriously affects the quality of cocoa pigment. For example, CN1028299852A discloses a method for extracting cocoa pigment from cocoa beans, which is an alkali extraction and acid precipitation method. After plate and frame filtration to remove impurities, the resin adsorption principle is used to elute, collect and dry. The resin regeneration of this invention requires a large amount of acid, alkali, water and ethanol, which causes great environmental pollution and makes sewage treatment difficult. Summary of the invention

[0004] In view of the above problems, the present invention provides a process for extracting water-soluble cocoa pigment for textile dyeing, which can extract water-soluble cocoa pigment from cocoa bean shells quickly, with low energy consumption, low cost and pollution-free. The obtained cocoa pigment has excellent color fastness and dyeing rate in textile dyeing applications, and has stable performance.

[0005] To achieve the above object, the technical solution adopted by the present invention is:

[0006] A process for extracting water-soluble cocoa pigment for textile dyeing comprises the following steps:

[0007] (1) Pretreatment: adding cellulase and pectinase to the raw cocoa bean shells, stirring and mixing them evenly, heating to 80-90° C. after enzymolysis, maintaining for 10-20 minutes to terminate the enzyme reaction, and then removing unreacted enzymes and solid impurities by filtering and membrane separation technology to obtain enzymolyzed cocoa bean shells;

[0008] (2) high temperature baking: baking the cocoa bean shells treated in step (1) at a temperature of 205-225° C. for 5-25 min;

[0009] (3) Continuous countercurrent extraction: The baked raw material is soaked and then fed into the feeding hopper, and countercurrent extraction is performed with water as the solvent to obtain an extract;

[0010] (4) Filtration and impurity removal: The extract is coarsely filtered and then finely filtered through a ceramic membrane to obtain a fine filtrate, and the fine filtrate is further ultrafiltered to remove macromolecular impurities to obtain a purified filtrate;

[0011] (5) Chemical modification: the purified filtrate is mixed with p-aminobenzenesulfonic acid, and a diazotization reaction is carried out under acidic conditions. The diazotization reaction is completed at 0-5°C for 2-4 hours, and then a non-ionic surfactant is slowly added, and the reaction is carried out at room temperature for 1-2 hours. The filtrate is obtained by centrifugation;

[0012] (6) Nanofiltration desalination and concentration: The filtrate obtained in step (5) is subjected to nanofiltration desalination and concentration to obtain a concentrated solution;

[0013] (7) Spray drying: The concentrated solution is spray dried to obtain a water-soluble cocoa pigment product.

[0014] As a further improvement of the above scheme, a process for extracting water-soluble cocoa pigment for textile dyeing comprises the following steps:

[0015] (1) Pretreatment: adding cellulase and pectinase to the raw cocoa bean shells, wherein the amount of cellulase and pectinase added is 0.5-2% of the mass of the cocoa bean shells, stirring and mixing uniformly, performing enzymolysis for 2-5 hours at a pH value of 4.5-5.5 and a temperature of 40-50° C., heating to 80-90° C. and maintaining for 10-20 minutes to terminate the enzyme reaction, and then removing unreacted enzymes and solid impurities by filtering and membrane separation technology to obtain enzymolyzed cocoa bean shells;

[0016] (2) high temperature baking: baking the cocoa bean shells treated in step (1) at a temperature of 205-225° C. for 5-25 min;

[0017] (3) Continuous countercurrent extraction: soak the baked raw material and then put it into the feeding hopper. When the raw material is soaked, the weight ratio of the raw material to water is 1:2. Water is used as the solvent for countercurrent extraction. During the extraction, the weight ratio of the feed amount to the water amount is 1:7. The extraction temperature is 80-100°C and the extraction time is 60-120 minutes to obtain an extract.

[0018] (4) Filtration and impurity removal: The extract is coarsely filtered and then finely filtered through a ceramic membrane to obtain a fine filtrate, and the fine filtrate is further ultrafiltered to remove macromolecular impurities to obtain a purified filtrate;

[0019] (5) Chemical modification: the purified filtrate is mixed with p-aminobenzenesulfonic acid, and a diazotization reaction is carried out under acidic conditions. The diazotization reaction is completed at 0-5°C for 2-4 hours, and then a non-ionic surfactant is slowly added, and the reaction is carried out at room temperature for 1-2 hours. The filtrate is obtained by centrifugation;

[0020] (6) Nanofiltration desalination and concentration: The filtrate obtained in step (5) is subjected to nanofiltration desalination and concentration to obtain a concentrated solution;

[0021] (7) Spray drying: The concentrated solution is spray dried using a pressure spray dryer with an air inlet temperature of 110-150° C. and an air outlet temperature of 80-90° C. to obtain a water-soluble cocoa pigment product.

[0022] This technical solution uses cellulase and pectinase to enzymatically hydrolyze cocoa bean shells to improve the release efficiency of the pigment, while the diazotization reaction and the addition of non-ionic surfactants improve the water solubility of the pigment, enhance its stability in aqueous media, improve the extraction efficiency and purity of the pigment, and make it more suitable for the field of textile dyeing.

[0023] As a further improvement of the above scheme, in step (1), the enzymatic hydrolysis is carried out for 3 hours at a pH value of 5.0 and a temperature of 40° C. This technical scheme can release the pigment more effectively and improve the extraction rate of the pigment by precisely controlling the enzymatic hydrolysis conditions, while maintaining the stability and water solubility of the pigment, thereby providing a better quality pigment source for textile dyeing.

[0024] As a further improvement of the above scheme, in the step (4), the extract is coarsely filtered through a 300-mesh filter cloth, the ceramic membrane is finely filtered through a 100-300 nm ceramic membrane, and the ultrafiltration membrane used to remove macromolecular impurities is an ultrafiltration membrane of 100,000-300,000 Daltons.

[0025] As a further improvement of the above scheme, in the step (5), the molar ratio of cocoa pigment to p-aminobenzenesulfonic acid in the purified filtrate is 1:50-70, and the diazotization reaction is carried out under acidic conditions of pH 4-5.

[0026] As a further improvement of the above scheme, in the step (5), the molar ratio of cocoa pigment to p-aminobenzenesulfonic acid in the purified filtrate is 1:50, and the diazotization reaction is carried out under acidic conditions of pH 5.

[0027] As a further improvement of the above scheme, the diazotization reaction in step (5) is to slowly add the sodium nitrite solution dropwise to the mixed filtrate, and the amount used is 1.1-2 times the equivalent.

[0028] As a further improvement of the above scheme, the nonionic surfactant in step (5) is selected from polyethylene glycol or polysorbate nonionic surfactants, and the added amount accounts for 0.1-1% of the total mass of the filtrate. This technical scheme further improves the water solubility of the pigment by adding the nonionic surfactant, and improves the dispersibility and stability of the pigment in the aqueous medium by reducing the surface tension and increasing the interaction between the pigment molecules and the water molecules.

[0029] As a further improvement of the above scheme, in step (6), the nanofiltration desalination and concentration uses a 100-1000 Dalton nanofiltration membrane to concentrate the solution to a Baume degree of 30-40.

[0030] Compared with the prior art, the present invention has the following beneficial effects: (1) the present invention can not only greatly improve the yield by performing Maillard reaction through high-temperature baking, but also make the color value of the cocoa pigment product higher. The present invention also adopts continuous countercurrent extraction technology for extraction, which reduces the amount of extraction solvent and improves the transfer rate of effective substances. The membrane equipment is used for impurity removal and concentration, and the processing capacity is large, and the energy consumption is extremely low. Most significantly, the combination of continuous countercurrent extraction equipment and membrane equipment realizes continuous production, greatly improves the stability of product quality, and is suitable for large-scale industrial production. Moreover, only water is used as the extraction solvent in this process, which realizes low energy consumption and truly achieves green environmental protection.

[0031] (2) The present invention adopts enzymatic hydrolysis for pretreatment, using a mixed enzyme of cellulase and pectinase, which helps to decompose the cell wall components in the cocoa bean shell, thereby making it easier for the pigment to be extracted in the subsequent steps. It can also decompose complex carbohydrates such as cellulose and pectin in the cocoa bean shell, thereby releasing pigment molecules and other valuable components, thereby improving the extraction rate of the pigment. Enzymatic hydrolysis combined with high temperature treatment can significantly increase the types of volatile substances in cocoa powder and help to generate heterocyclic compounds with nutty and creamy aromas;

[0032] (3) The present invention adopts chemical modification to improve the dyeing performance of the modified cocoa pigment. Specifically, the diazonium salt modification is used to introduce new functional groups, such as diazo groups, on the surface of the cocoa pigment molecules, thereby enhancing the interaction between the pigment molecules and water molecules, thereby improving the dispersibility of the pigment in water and enhancing its stability in solution; the p-aminobenzenesulfonic acid reacts with the surface of the cocoa pigment molecules to form a diazonium compound, and the formed diazonium compound is further covalently grafted with the surface of the cocoa pigment molecules to form a stable chemical bond, thereby enhancing the interaction between the pigment molecules and the textile fibers and improving the uniformity and color fastness of dyeing; however, the main coloring component of the cocoa pigment, polyflavonoid glycoside, has Multiple phenolic hydroxyl groups undergo coupling reaction with diazonium salts when modified by diazonium salts, destroying the conjugated system of polyflavonoid glycosides, thereby changing their surface properties and affecting the color and quality of cocoa pigments. In the present invention, a mixed enzyme is used for enzymolysis during pretreatment, and the purification process can significantly improve the purity of polyflavonoid glycosides, reduce other impurities that react with diazonium salts, thereby reducing potential damage to the conjugated system, and select appropriate reaction conditions, such as performing a diazotization reaction under acidic conditions, reacting at 0-5°C for 2-4h to complete the diazotization reaction, so as to reduce the decomposition of the diazonium salt and avoid unnecessary side reactions. Performing a diazotization reaction under such conditions can generate a diazonium salt without destroying the conjugated system of polyflavonoid glycosides. DETAILED DESCRIPTION

[0033] In order to enable those skilled in the art to better understand the technical solution, the present invention is described in detail below in conjunction with embodiments. The description in this section is only exemplary and explanatory and should not have any limiting effect on the scope of protection of the present invention.

[0034] Embodiment 1:

[0035] A process for extracting water-soluble cocoa pigment for textile dyeing comprises the following steps:

[0036] (1) Pretreatment: adding cellulase and pectinase to the raw cocoa bean shells, wherein the amount of cellulase and pectinase added is 1.0% of the mass of the cocoa bean shells, stirring and mixing uniformly, performing enzymolysis for 3 hours at a pH value of 5.0 and a temperature of 40° C., heating to 90° C. and maintaining for 10 minutes to terminate the enzyme reaction, and then removing unreacted enzymes and solid impurities by filtering and membrane separation technology to obtain enzymolyzed cocoa bean shells;

[0037] (2) high temperature baking: baking the cocoa bean shells treated in step (1) at a temperature of 205° C. for 25 min;

[0038] (3) Continuous countercurrent extraction: soak the baked raw material and then put it into the feeding hopper. When the raw material is soaked, the weight ratio of the raw material to water is 1:2. Water is used as the solvent for countercurrent extraction. During the extraction, the weight ratio of the feed amount to the water amount is 1:7. The extraction temperature is 95°C and the extraction time is 80 minutes to obtain an extract.

[0039] (4) Filtration and impurity removal: the extract is coarsely filtered and then finely filtered through a ceramic membrane to obtain a fine filtrate, and the fine filtrate is further ultrafiltered to remove macromolecular impurities to obtain a purified filtrate, wherein the extract is coarsely filtered through a 300-mesh filter cloth, the ceramic membrane fine filtration is a 100 nm ceramic membrane, and the ultrafiltration membrane used to remove macromolecular impurities is a 300,000 Dalton ultrafiltration membrane;

[0040] (5) Chemical modification treatment: the purified filtrate is mixed with p-aminobenzenesulfonic acid, and a diazotization reaction is carried out under acidic conditions. The diazotization reaction is completed at 3°C ​​for 3 hours. The diazotization reaction is carried out by slowly dropping a sodium nitrite solution into the mixed filtrate in an amount of 1.1 times the equivalent, and then slowly adding a non-ionic surfactant, reacting at room temperature for 1 hour, and obtaining a filtrate by centrifugation. The molar ratio of cocoa pigment to p-aminobenzenesulfonic acid in the purified filtrate is 1:50. The diazotization reaction is carried out under acidic conditions of pH 5. The non-ionic surfactant is selected from a polyethylene glycol non-ionic surfactant, and the amount added accounts for 0.5% of the total mass of the filtrate;

[0041] (6) Nanofiltration desalination and concentration: The filtrate obtained in step (5) is subjected to nanofiltration desalination and concentration to obtain a concentrated solution, wherein the nanofiltration desalination and concentration uses a 700 Dalton nanofiltration membrane and is concentrated to a solution with a Baume degree of 35;

[0042] (7) Spray drying: The concentrated solution is spray dried using a pressure spray dryer with an air inlet temperature of 110° C. and an air outlet temperature of 80° C. to obtain a water-soluble cocoa pigment product.

[0043] Embodiment 2:

[0044] A process for extracting water-soluble cocoa pigment for textile dyeing comprises the following steps:

[0045] (1) Pretreatment: adding cellulase and pectinase to the raw cocoa bean shells, the amount of cellulase and pectinase added is 0.5% of the mass of the cocoa bean shells, stirring and mixing evenly, performing enzymolysis for 2 hours at a pH of 5.5 and a temperature of 50° C., heating to 80° C. and maintaining for 20 minutes to terminate the enzyme reaction, and then removing unreacted enzymes and solid impurities by filtering and membrane separation technology to obtain enzymolyzed cocoa bean shells;

[0046] (2) high temperature baking: baking the cocoa bean shells treated in step (1) at a temperature of 225° C. for 20 min;

[0047] (3) Continuous countercurrent extraction: soak the baked raw material and then put it into the feeding hopper. When the raw material is soaked, the weight ratio of the raw material to water is 1:2. Water is used as the solvent for countercurrent extraction. During the extraction, the weight ratio of the feed amount to the water amount is 1:7. The extraction temperature is 80°C and the extraction time is 120 minutes to obtain an extract.

[0048] (4) Filtration and impurity removal: the extract is coarsely filtered and then finely filtered through a ceramic membrane to obtain a fine filtrate, and the fine filtrate is further ultrafiltered to remove macromolecular impurities to obtain a purified filtrate, wherein the extract is coarsely filtered through a 300-mesh filter cloth, the ceramic membrane fine filtration is a 300 nm ceramic membrane, and the ultrafiltration membrane used to remove macromolecular impurities is a 100,000 Dalton ultrafiltration membrane;

[0049] (5) Chemical modification treatment: the purified filtrate is mixed with p-aminobenzenesulfonic acid, and a diazotization reaction is carried out under acidic conditions. The diazotization reaction is completed at 0°C for 4 hours. The diazotization reaction is carried out by slowly dropping a sodium nitrite solution into the mixed filtrate in an amount of 1.5 times the equivalent, and then slowly adding a non-ionic surfactant, reacting at room temperature for 2 hours, and obtaining a filtrate by centrifugation. The molar ratio of cocoa pigment to p-aminobenzenesulfonic acid in the purified filtrate is 1:60. The diazotization reaction is carried out under acidic conditions of pH 4. The non-ionic surfactant is selected from polyethylene glycol non-ionic surfactant, and the amount added accounts for 0.1% of the total mass of the filtrate;

[0050] (6) Nanofiltration desalination and concentration: The filtrate obtained in step (5) is subjected to nanofiltration desalination and concentration to obtain a concentrated solution, wherein the nanofiltration desalination and concentration uses a 200 Dalton nanofiltration membrane and is concentrated to a solution with a Baume degree of 40;

[0051] (7) Spray drying: The concentrated solution is spray dried using a pressure spray dryer with an air inlet temperature of 150° C. and an air outlet temperature of 82° C. to obtain a water-soluble cocoa pigment product.

[0052] Embodiment 3:

[0053] A process for extracting water-soluble cocoa pigment for textile dyeing comprises the following steps:

[0054] (1) Pretreatment: adding cellulase and pectinase to the raw cocoa bean shells, wherein the amount of cellulase and pectinase added is 2.0% of the mass of the cocoa bean shells, stirring and mixing uniformly, performing enzymolysis for 5 hours at a pH value of 4.5 and a temperature of 45° C., heating to 86° C. and maintaining for 12 minutes to terminate the enzyme reaction, and then removing unreacted enzymes and solid impurities by filtering and membrane separation technology to obtain enzymolyzed cocoa bean shells;

[0055] (2) high temperature baking: baking the cocoa bean shells treated in step (1) at a temperature of 210° C. for 10 min;

[0056] (3) Continuous countercurrent extraction: soak the baked raw material and then put it into the feeding hopper. When the raw material is soaked, the weight ratio of the raw material to water is 1:2. Water is used as the solvent for countercurrent extraction. During the extraction, the weight ratio of the feed amount to the water amount is 1:7. The extraction temperature is 100°C and the extraction time is 65 minutes to obtain an extract.

[0057] (4) Filtration and impurity removal: the extract is coarsely filtered and then finely filtered through a ceramic membrane to obtain a fine filtrate, and the fine filtrate is further ultrafiltered to remove macromolecular impurities to obtain a purified filtrate, wherein the extract is coarsely filtered through a 300-mesh filter cloth, the ceramic membrane fine filtration is a 200 nm ceramic membrane, and the ultrafiltration membrane used to remove macromolecular impurities is a 200,000 Dalton ultrafiltration membrane;

[0058] (5) Chemical modification treatment: the purified filtrate is mixed with p-aminobenzenesulfonic acid, and a diazotization reaction is carried out under acidic conditions. The diazotization reaction is completed at 5° C. for 2 hours. The diazotization reaction is carried out by slowly adding a sodium nitrite solution dropwise to the mixed filtrate in an amount of 1.8 times the equivalent, and then slowly adding a non-ionic surfactant, reacting at room temperature for 1 hour, and obtaining a filtrate by centrifugation. The molar ratio of cocoa pigment to p-aminobenzenesulfonic acid in the purified filtrate is 1:50. The diazotization reaction is carried out under acidic conditions of pH 5. The non-ionic surfactant is selected from a polysorbate non-ionic surfactant, and the amount added accounts for 1.0% of the total mass of the filtrate;

[0059] (6) Nanofiltration desalination and concentration: The filtrate obtained in step (5) is subjected to nanofiltration desalination and concentration to obtain a concentrated solution, wherein the nanofiltration desalination and concentration uses a 1000 Dalton nanofiltration membrane and is concentrated to a solution with a Baume degree of 30;

[0060] (7) Spray drying: The concentrated solution is spray dried using a pressure spray dryer with an air inlet temperature of 125° C. and an air outlet temperature of 84° C. to obtain a water-soluble cocoa pigment product.

[0061] Comparative Example 1:

[0062] The difference between this comparative example and Example 1 is that no enzyme is used for pretreatment, but citric acid is used for pickling, followed by washing with clean water and then high-temperature baking. The subsequent steps are the same as in Example 1.

[0063] Comparative Example 2:

[0064] The difference between this comparative example and Example 1 is that, in the pretreatment step, a single cellulase is used instead of pectinase, and the other subsequent steps are the same as those in Example 1.

[0065] Comparative Example 3:

[0066] The difference between this comparative example and Example 1 is that step (5) chemical modification treatment is omitted, and the process directly proceeds from step (4) filtration and impurity removal to step (6) nanofiltration desalination and concentration. The other contents are the same as Example 1.

[0067] Comparative Example 4:

[0068] The difference between this comparative example and Example 1 is that in step (5) of the chemical modification treatment, a nonionic surfactant is directly added for modification, and the diazotization reaction is omitted. The other contents are the same as those in Example 1.

[0069] Comparative Example 5:

[0070] The difference between this comparative example and Example 1 is that in step (5) of the chemical modification treatment, the addition of the nonionic surfactant is omitted and the diazotization reaction is directly carried out. The other contents are the same as those in Example 1.

[0071] Comparative Example 6:

[0072] The difference between this comparative example and Example 1 is that the pretreatment in step (1) and the chemical modification in step (5) are omitted at the same time, and the comparative example comprises the following steps:

[0073] (1) High temperature baking: baking the cocoa bean shell raw material at a high temperature of 205° C. for 25 min;

[0074] (2) Continuous countercurrent extraction: soak the baked raw material and then put it into the feeding hopper. When the raw material is soaked, the weight ratio of the raw material to water is 1:2. Water is used as the solvent for countercurrent extraction. During the extraction, the weight ratio of the feed amount to the water amount is 1:7. The extraction temperature is 95°C and the extraction time is 80 minutes to obtain an extract.

[0075] (3) Filtration and impurity removal: the extract is coarsely filtered and then finely filtered through a ceramic membrane to obtain a fine filtrate, and the fine filtrate is further ultrafiltered to remove macromolecular impurities to obtain a purified filtrate, wherein the extract is coarsely filtered through a 300-mesh filter cloth, the ceramic membrane fine filtration is a 100 nm ceramic membrane, and the ultrafiltration membrane used to remove macromolecular impurities is a 300,000 Dalton ultrafiltration membrane;

[0076] (4) Nanofiltration desalination and concentration: The purified filtrate obtained in step (3) is subjected to nanofiltration desalination and concentration to obtain a concentrated solution, wherein the nanofiltration desalination and concentration uses a 700 Dalton nanofiltration membrane and is concentrated to a solution with a Baume degree of 35;

[0077] (5) Spray drying: The concentrated solution is spray dried using a pressure spray dryer with an air inlet temperature of 110° C. and an air outlet temperature of 80° C. to obtain a water-soluble cocoa pigment product.

[0078] The water-soluble cocoa pigments obtained through the extraction process in the above Examples 1-3 and Comparative Examples 1-6 were subjected to performance testing. The content of the pigment in the cocoa bean shells before and after extraction was determined by high performance liquid chromatography to calculate the extraction rate. The color value of the cocoa pigment was determined by an ultraviolet-visible spectrophotometer, and the energy consumption during the extraction process was recorded. The measurement results are shown in the following table.

[0079] Table 1

[0080] Extraction rate % Color price E1% 1cm Energy consumption kWh Example 1 13.1 104 38.6 Example 2 12.6 97 40.9 Example 3 10.8 89 39.3 Comparative Example 1 8.2 43 42.1 Comparative Example 2 9.7 73 39.2 Comparative Example 3 12.3 94 35.6 Comparative Example 4 11.4 92 37.5 Comparative Example 5 11.8 87 35.8 Comparative Example 6 7.4 56 33.7

[0081] The cocoa pigment products obtained in Examples 1-3 and Comparative Examples 1-6 were applied in the field of textile dyeing. The cocoa pigment was dissolved in a solvent, and the textile was dyed by immersion dyeing. The dyed textile was then subjected to physical testing, wherein the ISO 105-X12 standard was used to test the rubbing fastness, and a spectrophotometer was used to measure the absorbance of the cocoa pigment in the solution at different times to calculate the dyeing rate. The dyeing temperature was 50-110° C., and the temperature was gradually increased for dyeing. The test results are shown in the following table.

[0082] Table 2

[0083]

[0084]

[0085] It should be noted that, in this article, the terms: include, contain and any other variants are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. Specific examples are used in this article to illustrate the principle and implementation of the technical solution of the present invention. The above examples are only used to help understand the method of the present invention and its core idea. The above is only a preferred implementation of the present invention. It should be pointed out that due to the limitations of textual expression and the objective existence of infinite specific structures, for ordinary technicians in this technical field, without departing from the principle of the present invention, several improvements, modifications or changes can be made, and the above technical features can also be combined in an appropriate manner; these improvements, modifications, changes or combinations, or the direct application of the concept and technical solution of the present invention to other occasions without improvement, should be regarded as the protection scope of the present invention.

Claims

1. A process for extracting water-soluble cocoa pigment for textile dyeing, characterized in that: The following steps are involved: (1) Pretreatment: adding cellulase and pectinase to the raw cocoa bean shells, stirring and mixing them evenly, heating to 80-90° C. after enzymolysis, maintaining for 10-20 minutes to terminate the enzyme reaction, and then removing unreacted enzymes and solid impurities by filtering and membrane separation technology to obtain enzymolyzed cocoa bean shells; (2) high temperature baking: baking the cocoa bean shells treated in step (1) at a temperature of 205-225° C. for 5-25 min; (3) Continuous countercurrent extraction: The baked raw material is soaked and then fed into the feeding hopper, and countercurrent extraction is performed with water as the solvent to obtain an extract; (4) Filtration and impurity removal: The extract is coarsely filtered and then finely filtered through a ceramic membrane to obtain a fine filtrate, and the fine filtrate is further ultrafiltered to remove macromolecular impurities to obtain a purified filtrate; (5) Chemical modification: the purified filtrate is mixed with p-aminobenzenesulfonic acid, and a diazotization reaction is carried out under acidic conditions. The diazotization reaction is completed at 0-5°C for 2-4 hours, and then a non-ionic surfactant is slowly added, and the reaction is carried out at room temperature for 1-2 hours. The filtrate is obtained by centrifugation; (6) Nanofiltration desalination and concentration: The filtrate obtained in step (5) is subjected to nanofiltration desalination and concentration to obtain a concentrated solution; (7) Spray drying: The concentrated solution is spray dried to obtain a water-soluble cocoa pigment product.

2. A process for extracting water-soluble cocoa pigment for textile dyeing according to claim 1, characterized in that: The following steps are involved: (1) Pretreatment: adding cellulase and pectinase to the raw cocoa bean shells, wherein the amount of cellulase and pectinase added is 0.5-2% of the mass of the cocoa bean shells, stirring and mixing uniformly, performing enzymolysis for 2-5 hours at a pH value of 4.5-5.5 and a temperature of 40-50° C., heating to 80-90° C. and maintaining for 10-20 minutes to terminate the enzyme reaction, and then removing unreacted enzymes and solid impurities by filtering and membrane separation technology to obtain enzymolyzed cocoa bean shells; (2) high temperature baking: baking the cocoa bean shells treated in step (1) at a temperature of 205-225° C. for 5-25 min; (3) Continuous countercurrent extraction: soak the baked raw material and then put it into the feeding hopper. When the raw material is soaked, the weight ratio of the raw material to water is 1:

2. Water is used as the solvent for countercurrent extraction. During the extraction, the weight ratio of the feed amount to the water amount is 1:

7. The extraction temperature is 80-100°C and the extraction time is 60-120 minutes to obtain an extract. (4) Filtration and impurity removal: The extract is coarsely filtered and then finely filtered through a ceramic membrane to obtain a fine filtrate, and the fine filtrate is further ultrafiltered to remove macromolecular impurities to obtain a purified filtrate; (5) Chemical modification: the purified filtrate is mixed with p-aminobenzenesulfonic acid, and a diazotization reaction is carried out under acidic conditions. The diazotization reaction is completed at 0-5°C for 2-4 hours, and then a non-ionic surfactant is slowly added, and the reaction is carried out at room temperature for 1-2 hours. The filtrate is obtained by centrifugation; (6) Nanofiltration desalination and concentration: The filtrate obtained in step (5) is subjected to nanofiltration desalination and concentration to obtain a concentrated solution; (7) Spray drying: The concentrated solution is spray dried using a pressure spray dryer with an air inlet temperature of 110-150° C. and an air outlet temperature of 80-90° C. to obtain a water-soluble cocoa pigment product.

3. A process for extracting water-soluble cocoa pigment for textile dyeing according to claim 2, characterized in that: In the step (1), the enzymatic hydrolysis is carried out for 3 hours at a pH value of 5.0 and a temperature of 40°C.

4. A process for extracting water-soluble cocoa pigment for textile dyeing according to claim 1, characterized in that: In the step (4), the extract is coarsely filtered through a 300-mesh filter cloth, the ceramic membrane is finely filtered through a 100-300 nm ceramic membrane, and the ultrafiltration membrane used to remove macromolecular impurities is an ultrafiltration membrane of 100,000-300,000 Daltons.

5. A process for extracting water-soluble cocoa pigment for textile dyeing according to claim 1, characterized in that: In the step (5), the molar ratio of cocoa pigment to p-aminobenzenesulfonic acid in the purified filtrate is 1:50-70, and the diazotization reaction is carried out under acidic conditions of pH 4-5.

6. A process for extracting water-soluble cocoa pigment for textile dyeing according to claim 5, characterized in that: In the step (5), the molar ratio of cocoa pigment to p-aminobenzenesulfonic acid in the purified filtrate is 1:50, and the diazotization reaction is carried out under acidic conditions of pH 5.

7. A process for extracting water-soluble cocoa pigment for textile dyeing according to claim 5, characterized in that: The diazotization reaction in step (5) is carried out by slowly adding the sodium nitrite solution dropwise to the mixed filtrate, and the amount used is 1.1-2 times the equivalent.

8. A process for extracting water-soluble cocoa pigment for textile dyeing according to claim 1, characterized in that: In the step (5), the nonionic surfactant is selected from polyethylene glycol or polysorbate nonionic surfactant, and the added amount accounts for 0.1-1% of the total mass of the filtrate.

9. A process for extracting water-soluble cocoa pigment for textile dyeing according to claim 1, characterized in that: In the step (6), the nanofiltration desalination and concentration uses a nanofiltration membrane of 100-1000 Daltons to concentrate the solution to a Baume degree of 30-40.

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