Water-soluble liquid curcumin as well as preparation method and application thereof

Abstract

The invention relates to the technical field of deep processing of natural products, in particular to water-soluble liquid curcumin as well as a preparation method and application thereof. Curcumin is used as a raw material, an antioxidant, a food surfactant and the like are matched, edible ethanol is used as a solvent, and a temperature control crystallization technology is adopted to prepare curcumin compound crystals; and with the curcumin compound crystal as a raw material and a surfactant as an auxiliary material, the water-soluble liquid curcumin which is high in content, good in stability and clear and transparent in solution is obtained by combining technologies such as temperature-controlled emulsification, heat preservation, dilution and the like. The product can meet the requirements on hue, clarity and stability of the curcumin aqueous solution in different application scenes, and is suitable for the fields of food, medicine, cosmetics and the like.

Description

Technical Field

[0001] The invention relates to the technical field of deep processing of natural products, and in particular to a water-soluble liquid curcumin and a preparation method and application thereof. Background Art

[0002] Curcumin is a natural polyphenol obtained by extracting, refining, crystallizing and drying the dried rhizome of the perennial herb Curcuma longa L. of the ginger family. Its main components are monodemethoxycurcumin and bisdemethoxycurcumin. Curcumin has good coloring ability and has a long history of consumption as a food raw material and natural coloring ingredient around the world. Turmeric is also a Chinese medicine raw material. It was first seen in the Tang Materia Medica in China. It has the effects of "breaking blood and promoting qi, dredge menstruation and relieving pain". Modern medical research has also confirmed that curcumin has good anti-inflammatory, antioxidant, free radical scavenging, tumor inhibition, cardiovascular protection and other pharmacological effects, and has good preventive and therapeutic effects on various inflammations and lesions.

[0003] Curcumin is basically insoluble in water, but easily soluble in ethanol, glacial glycol, and propylene glycol. It has good heat resistance, but is sensitive to light, and is easily degraded and faded in a light environment, and is easily precipitated in an acidic environment. Curcumin is sensitive to pH value, and the color of the solution changes with the pH value. It appears "lemon yellow to yellow" in acidic water, and turns "red" in alkaline water, showing "orange-red to red". The color will deepen with the increase of pH value, and when the pH value is adjusted back to acidic, the solution color will change to "lemon yellow to yellow".

[0004] In actual application, the poor water solubility of curcumin and the easy change of solution color greatly limit the promotion and application of curcumin products, and the good efficacy of curcumin cannot be effectively exerted. Therefore, how to improve its solubility and stability, expand the color range in neutral to acidic environments and the application range in food, health food, medicine and other fields, improve the application effect, and maximize the efficacy of curcumin has become an important research topic in the industry.

[0005] Through searching, it is found that how to improve the solubility and stability of curcumin, and the preparation methods for meeting the needs of different application scenarios have been widely studied. For example, CN 115176989 A (a transparent curcumin oil solution and its preparation method and application) uses curcumin and oil to heat and mix, add surfactants and crystallization inhibitors, and finally add stabilizers. By stirring, a transparent curcumin oil solution with a curcumin content of about 1.5% is finally obtained. CN 101869692A (a curcumin-free self-microemulsion and its preparation method) uses fatty acid oil, surfactant, and co-surfactant to mix and stir with curcumin substances to obtain a microemulsion of turmeric substances. CN 110934253 A (preparation method of nano-scale transparent water-dispersed curcumin) uses curcumin, surfactant, co-emulsifier, and water to form a suspension, and then grinds and sieves to obtain a nano-scale curcumin aqueous dispersion. CN 113117091 A (a water-soluble curcumin preparation and its preparation method) adopts curcumin, antioxidant, surfactant, auxiliary emulsifier and water, and then grinds them in a grinder to obtain a water-soluble curcumin emulsion with a curcumin content of 1-3% and a single solution color.

[0006] At present, the existing technology has the problems of low curcumin content, complex preparation process, use of a large amount of non-food surfactants, poor product safety, and especially the prepared water-soluble curcumin product has a single color tone and cannot meet the needs of different application scenarios. Therefore, it is very necessary to provide a water-soluble liquid curcumin with high curcumin content, simple preparation process, high product safety, rich product color tone, and can meet the needs of different application scenarios. Summary of the invention

[0007] In order to solve the deficiencies and defects of the prior art, the primary purpose of the present invention is to provide a method for preparing a water-soluble liquid curcumin. The method first uses curcumin as a raw material, an antioxidant, a food surfactant, etc., edible ethanol as a solvent, and adopts a temperature-controlled crystallization technology to prepare a curcumin complex crystal; then uses the curcumin complex crystal as a raw material, supplemented with a food surfactant, and uses temperature-controlled emulsification, insulation, dilution and other technologies to obtain a water-soluble liquid curcumin with high content, good stability and clear and transparent solution, and by adjusting process parameters such as emulsification and insulation, the color tone of the aqueous solution can be changed from "bright yellow to orange-red", which can meet the needs of different application scenarios.

[0008] Another object of the present invention is to provide a water-soluble liquid curcumin prepared by the above-mentioned preparation method. The water-soluble liquid curcumin product has the characteristics of high content, good stability and clear and transparent solution. Compared with the water-soluble curcumin prepared by the conventional method, the product of the present invention can achieve the change of the color tone of the aqueous solution with the same concentration from "bright yellow to orange red" through the regulation of process parameters, and has good stability in an acidic solution environment, and can meet the requirements of the color tone, clarity and stability of the curcumin aqueous solution in different application scenarios. The product is suitable for the fields of food, medicine, cosmetics, etc.

[0009] Another object of the present invention is to provide the application of the water-soluble liquid curcumin.

[0010] The objective of the present invention is achieved through the following technical solutions:

[0011] A method for preparing water-soluble liquid curcumin comprises the following steps:

[0012] (1) adding curcumin, antioxidant and surfactant A to ethanol and stirring evenly, heating the material under stirring until the material is completely dissolved into a transparent state, and then keeping the temperature at 85° C. to 95° C. for 0.5 h to 4 h; after the heat preservation treatment, slowly cooling until crystals precipitate, collecting the crystal precipitate, and obtaining curcumin complex crystals;

[0013] (2) under vacuum, mixing surfactant B and the curcumin complex crystals collected in step (1), heating the mixture to completely dissolve the mixture until it becomes transparent, and then keeping the mixture at 80° C. to 150° C. for 10 to 100 minutes; and cooling the mixture to obtain a water-soluble turmeric concentrate;

[0014] (3) adding the diluent to the water-soluble curcumin concentrate obtained in step (2) under stirring and stirring to obtain a water-soluble liquid curcumin;

[0015] The antioxidant described in step (1) is at least one of VC, sodium isoVC, ascorbyl palmitate, EGCG, VE, mixed tocopherols, TBHQ and BHA, and the amount of the antioxidant is 0.001% to 5% of the mass of the water-soluble liquid curcumin;

[0016] The surfactant A described in step (1) is at least one of sucrose fatty acid ester and sucrose acetate isobutyrate, and the amount of the surfactant A accounts for 0.5% to 15% of the mass of the water-soluble liquid curcumin;

[0017] The concentration (v / v) of ethanol in step (1) is 90% to 98%;

[0018] The mass ratio of ethanol to curcumin in step (1) is preferably (10:1) to (20:1);

[0019] The heating temperature in step (1) is preferably 80°C to 90°C;

[0020] The method for collecting the crystal precipitate in step (1) comprises one or a combination of medium filtration and centrifugal separation;

[0021] The heating temperature in step (2) is preferably 70-80°C;

[0022] The mass content of the curcumin complex crystals in the water-soluble turmeric concentrate described in step (2) is 5% to 35%;

[0023] The surfactant B described in step (2) is at least one of polyoxyethylene (20) sorbitan monolaurate, polyoxyethylene (20) sorbitan monopalmitate, polyoxyethylene (20) sorbitan monostearate, polyoxyethylene (20) sorbitan monooleate and polyglycerol fatty acid esters, and the mass content of the surfactant B in the water-soluble turmeric concentrate is 95% to 65%;

[0024] The vacuum condition described in step (2) is a vacuum degree of -0.06MPa to -0.1MPa;

[0025] The vacuum condition described in step (2) is preferably a vacuum degree of -0.8 MPa;

[0026] The insulation condition described in step (2) is preferably 140° C. to 145° C. for 30 min to 45 min, under which an orange-red to orange-red final product can be obtained;

[0027] The diluent described in step (3) is at least one of water, glycerol, ethanol and propylene glycol, and the amount of the diluent is 0.001% to 20% of the mass of the water-soluble turmeric concentrate;

[0028] A water-soluble liquid curcumin is obtained by the above preparation method;

[0029] The water-soluble liquid curcumin can be used in the fields of food, medicine or cosmetics;

[0030] The present invention has no particular limitation on the form of the food, which can be added to liquid food or solid food, and is preferably prepared as a beverage.

[0031] If the food is a health food, the present invention has no particular limitation on the dosage form of the health food, which may be a solid granule, capsule, tablet, oral liquid, etc.

[0032] Principle of the present invention:

[0033] Curcumin is a polyphenol substance containing a diketone group and multiple hydroxyl groups in its molecular structure. It is sensitive to light, heat, oxygen, metal ions, etc., and is easily oxidized and degraded. It is also relatively sensitive to pH value. When the pH value of the solution is alkaline, the diketone groups on the turmeric molecular structure combine to cause the electron cloud to deviate, and the conjugation effect is enhanced, appearing as "orange-red to red"; when the pH value of the solution is acidic, the diketone groups are opened, and the conjugation effect is weakened, appearing as "lemon yellow to yellow".

[0034] (1) The present invention first dissolves curcumin, an antioxidant and a surfactant A in ethanol, wherein the main chain of curcumin is an unsaturated aliphatic and aromatic group, and has both a hydrophilic group and a lipophilic group. The surfactant A used in the present invention is sucrose fatty acid ester, sucrose acetate isobutyrate ester and the like, which has good oil-water amphiphilicity and can well improve the solubility of curcumin in an aqueous solution system and an ethanol system; by heating and heat preservation, the curcumin, the antioxidant, the surfactant A and the like are completely dissolved in the hot ethanol in a molecular state; then, as the temperature decreases, the solubility of curcumin decreases, and it gradually crystallizes, and in the process of forming crystals, it entrains the antioxidant, the sucrose ester and the like to form a composite crystal; the antioxidant slows down the generation of free radicals by consuming oxygen or chelating metal ions, thereby playing the effect of delaying the degradation of curcumin, and compared with the conventional method, that is, directly mixing curcumin and the antioxidant, the present invention is more conducive to delaying the oxidation of curcumin. The invention improves the solubility of curcumin and enhances the stability of curcumin by selecting appropriate types and dosages of oxidants and surfactants and combining operations such as heat preservation and low-temperature crystallization.

[0035] (2) The types of surfactant A, antioxidant, etc. selected in the present invention are very critical. Among them, surfactant A and curcumin undergo esterification, which enhances the stability of curcumin. On the other hand, since curcumin molecules contain hydroxyl groups and the sucrose groups at the ester-end of sucrose esters also contain a large number of hydroxyl groups, dehydration reactions will occur between hydroxyl groups when heated to form "caramel-like substances". As the heating temperature increases and the heating time increases, the dehydration reaction will increase, and the amount of "caramel-like substances" generated will increase, making the color of the product darker, gradually changing from "lemon yellow" to "orange-red". The selection of antioxidants will also affect the color tone of the final product. Therefore, the present invention can achieve the change of the color tone of the turmeric aqueous solution of the same concentration from "bright yellow to orange-red" by adding surfactants, selecting antioxidants, and regulating the changes in process parameters, and has good stability in an acidic solution environment, which can meet the requirements of the color tone, clarity, and stability of the turmeric aqueous solution in different application scenarios. It is worth noting that in this step, the temperature and time of heat preservation are very critical. Although the caramelization reaction can be continued at too high a temperature or too long a time, the color value loss of curcumin is relatively high for curcumin at too high a temperature or too long a time. Therefore, the present invention selects to perform caramelization at a temperature and time just after caramelization occurs, which results in relatively less loss of color value of curcumin. At the same time, due to the use of antioxidant ingredients in step (1), the stability of curcumin in step (2) is ensured, and the degradation loss of curcumin due to heat is reduced.

[0036] Compared with the prior art, the present invention has the following advantages and effects:

[0037] (1) Compared with the existing technology, the preparation method provided by the present invention adopts surfactants, antioxidants and processing aids that are safe for use in food as specified in GB2760-2024, and the product is safer. The production process does not use complex emulsification, homogenization, grinding and other processes, and the process control is more convenient, the cost is low, and it is more conducive to the industrial scale-up of the product.

[0038] (2) The present invention firstly adopts the technology of co-dissolution crystallization of curcumin with antioxidants, sucrose esters, etc., so that curcumin can be more effectively protected in the formed composite crystals. At the same time, the presence of sucrose esters, etc. is more conducive to improving the solubility of curcumin, increasing the water solubility and stability of curcumin, and ensuring that the product of the present invention can be stably used in liquid foods such as beverages.

[0039] (3) In the preparation process of the present invention, by adjusting the temperature and time of heating and insulation, the color change of the product can be adjusted, and a water-soluble liquid curcumin product with a color of "bright yellow to orange red" can be prepared by a technical solution, thereby meeting the requirements of curcumin color in different application scenarios and changing the problem of single color of curcumin solution in the current technology.

[0040] (4) The water-soluble liquid curcumin product prepared by the present invention has a high curcumin content of up to 21.3%. The product has good water solubility, the solution is clear and transparent, and the T680nm of a 1% aqueous solution can reach up to more than 98%. It also significantly improves the stability under neutral and acidic conditions, and can meet the application requirements in the fields of food, medicine, cosmetics, etc. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figure 1 This is a graph showing the dissolution effect of 1% solution of Examples 1 to 4.

[0042] Figure 2 This is a graph showing the dissolution effect of 1% solution of Comparative Examples 1 to 4.

[0043] Figure 3 This is a graph showing the test results of the 6-day light color stability (neutral conditions: pH=7.0) of Examples 1 to 4.

[0044] Figure 4 This is a graph showing the test results of the 6-day light color stability (neutral conditions: pH=7.0) of Comparative Examples 1 to 4.

[0045] Figure 5 It is a graph showing the test results of the 5-day light color stability (acidic conditions: pH=3.2) of Examples 1 to 4.

[0046] Figure 6 This is a graph showing the test results of the 5-day light color stability (acidic conditions: pH=3.2) of Comparative Examples 1 to 4. DETAILED DESCRIPTION

[0047] The present invention is further described in detail below in conjunction with embodiments and drawings, but the embodiments of the present invention are not limited thereto.

[0048] Unless otherwise specified, the technical means used in the examples are conventional means known to those skilled in the art. Unless otherwise specified, the reagents, methods and equipment used in the present invention are conventional reagents, methods and equipment in the art.

[0049] In this embodiment, curcumin is commercially available, and the curcumin content is 95%.

[0050] Example 1

[0051] (1) accurately weighing 19.7 g of curcumin, 1.2 g of ascorbyl palmitate, 0.8 g of mixed tocopherols and 5 g of sucrose fatty acid ester, adding them to 220 g of 95% (V / V) edible ethanol and stirring them evenly, heating them to 90° C. under stirring to completely dissolve the materials into a transparent state, and then keeping the temperature at this temperature for 2.5 h; starting to cool after the heat treatment, gradually cooling to 20° C. within 12 h; collecting the composite crystals formed after cooling by centrifugation to obtain 25.7 g of curcumin composite crystals;

[0052] (2) adding 70.8 g of polyoxyethylene (20) sorbitan monooleate to a vacuum stirring tank, and then adding the curcumin complex crystals collected in step (1), stirring and heating to 70-80° C. under a vacuum state of -0.8 MPa to completely dissolve the material into a transparent state; then continuing to heat to 95° C. and keeping the temperature for 20 min, and then naturally cooling to room temperature to obtain a water-soluble turmeric concentrate;

[0053] (3) Weigh 6.5 g of water and slowly add it to the cooled water-soluble turmeric concentrate in step (2), stirring evenly to obtain a water-soluble liquid curcumin product with good water solubility and in a transparent state.

[0054] After testing, the water-soluble liquid curcumin product obtained in this embodiment has good water solubility, with a curcumin content of 18.0%, a 1% aqueous solution T680nm=85.3%, a "bright yellow" color, Abs=1.0 color difference value (L=85.56, a=-5.26, b=55.33).

[0055] Example 2

[0056] (1) accurately weighing 19.7 g of curcumin, 1.2 g of ascorbyl palmitate, 0.8 g of mixed tocopherols and 5 g of sucrose acetate isobutyrate, adding them to 220 g of 95% (V / V) edible ethanol and stirring them evenly, heating them to 90° C. while stirring so that the materials are completely dissolved into a transparent state, and then keeping the temperature at this temperature for 2.5 h; starting to cool after the heat treatment, gradually cooling to 20° C. within 12 h; collecting the composite crystals formed after cooling by centrifugation to obtain 25.9 g of curcumin composite crystals;

[0057] (2) adding 70.5 g of polyoxyethylene (20) sorbitan monooleate to a vacuum stirring tank, and then adding the curcumin complex crystals collected in step (1), stirring and heating to 70-80° C. under a vacuum state of -0.8 MPa, so that the material is completely dissolved to a transparent state; then continuing to heat to 120° C. and maintaining for 30 min, and then naturally cooling to room temperature to obtain a water-soluble turmeric concentrate;

[0058] (3) Weigh 6.5 g of water and slowly add it to the cooled water-soluble turmeric concentrate in step (2), stirring evenly to obtain a water-soluble liquid curcumin product with good water solubility and in a transparent state.

[0059] After testing, the water-soluble liquid curcumin product obtained in this embodiment has good water solubility, a curcumin content of 17.6%, a 1% aqueous solution T680nm=87.24%, an aqueous solution color presenting "orange-yellow", Abs=1.0 color difference value (L=87.49, a=-3.57, b=57.15).

[0060] Example 3

[0061] (1) accurately weighing 19.7 g of curcumin, 1.2 g of ascorbyl palmitate, 0.8 g of mixed tocopherols and 5 g of sucrose fatty acid ester, adding them to 220 g of 95% (V / V) edible ethanol and stirring them evenly, heating them to 90° C. under stirring to completely dissolve the materials into a transparent state, and then keeping the temperature at this temperature for 2.5 h; starting to cool after the heat treatment, gradually cooling to 20° C. within 12 h; collecting the composite crystals formed after cooling by centrifugation to obtain 26.0 g of curcumin composite crystals;

[0062] (2) adding 67.0 g of polyoxyethylene (20) sorbitan monopalmitate into a vacuum stirring tank, and then adding the curcumin complex crystals collected in step (1), stirring and heating to 70-80° C. under a vacuum state of -0.8 MPa, so that the material is completely dissolved to a transparent state; then continuing to heat to 140° C. and maintaining for 30 min, and then naturally cooling to room temperature to obtain a water-soluble turmeric concentrate;

[0063] (3) Weigh 6.5 g of water and slowly add it to the cooled water-soluble turmeric concentrate in step (2), stirring evenly to obtain a water-soluble, transparent, water-soluble liquid curcumin product.

[0064] After testing, the water-soluble liquid turmeric product obtained in this embodiment has good water solubility, a curcumin content of 18.0%, a 1% aqueous solution T680nm=92.31%, an aqueous solution color presents "orange-red", Abs=1.0 color difference value (L=89.02, a=-2.35, b=59.56).

[0065] Example 4

[0066] (1) accurately weighing 19.7 g of curcumin, 1.2 g of ascorbyl palmitate, 0.8 g of mixed tocopherols and 5 g of sucrose fatty acid ester, adding them to 220 g of 95% (V / V) edible ethanol and stirring them evenly, heating them to 90° C. under stirring to completely dissolve the materials into a transparent state, and then keeping the temperature at this temperature for 2.5 h; starting to cool after the heat treatment, gradually cooling to 20° C. within 12 h; collecting the composite crystals formed after cooling by centrifugation to obtain 26.2 g of curcumin composite crystals;

[0067] (2) adding 53.1 g of polyoxyethylene (20) sorbitan monooleate to a vacuum stirring tank, and then adding the curcumin complex crystals collected in step (1), stirring and heating to 70-80° C. under a vacuum state of -0.8 MPa to completely dissolve the material until it becomes transparent; then continuing to heat to 145° C. and maintaining for 45 min, and then naturally cooling to room temperature to obtain a water-soluble turmeric concentrate;

[0068] (3) Weigh 6.5 g of water and slowly add it to the cooled water-soluble turmeric concentrate in step (2), stirring evenly to obtain a water-soluble, transparent, water-soluble liquid curcumin product.

[0069] After testing, the water-soluble liquid curcumin product obtained in this embodiment has good water solubility, a curcumin content of 21.3%, a 1% aqueous solution T680nm = 98.6%, an aqueous solution color presents "orange-red", Abs = 1.0 color difference value (L = 90.52, a = 0.57, b = 60.29).

[0070] Comparative Example 1 (the difference from Example 1 is that sucrose fatty acid ester is not added)

[0071] (1) Accurately weighing 19.7 g of curcumin, 1.2 g of ascorbyl palmitate, and 0.8 g of mixed tocopherols, adding them to 220 g of 95% (V / V) edible ethanol and stirring them evenly, heating them to 90° C. while stirring so that the materials are completely dissolved into a transparent state, and then keeping the temperature at this temperature for 2.5 h; starting to cool after the heat treatment, gradually cooling to 20° C. within 12 h; collecting the complex crystals formed after cooling by centrifugation to obtain 21.1 g of curcumin complex crystals;

[0072] (2) adding 70.8 g of polyoxyethylene (20) sorbitan monooleate to a vacuum stirring tank, and then adding the curcumin complex crystals collected in step (1), stirring and heating to 70-80° C. under a vacuum state of -0.8 MPa to completely dissolve the material until it becomes transparent; then continuing to heat to 95° C. and keeping the temperature for 20 min, and then naturally cooling to room temperature to obtain a turmeric concentrate;

[0073] (3) Weigh 6.5 g of water and slowly add it to the cooled turmeric concentrate in step (2), stirring evenly to obtain a liquid curcumin product.

[0074] After testing, the curcumin content of the liquid curcumin product obtained in this embodiment is 17.5%, the T680nm of the 1% aqueous solution is 75.3%, the color tone of the aqueous solution is "green-yellow", and the color difference value Abs is 1.0 (L=75.36, a=-8.20, b=57.53). Comparative Example 2 (the difference from Example 2 is that the type of antioxidant is different)

[0075] (1) accurately weighing 19.7 g of curcumin, 1.2 g of tea polyphenols, 0.8 g of BHT and 5 g of sucrose fatty acid ester, adding them to 220 g of 95% (V / V) edible ethanol and stirring them evenly, heating them to 90° C. under stirring to completely dissolve the materials into a transparent state, and then keeping the temperature at this temperature for 2.5 h; starting to cool after the heat treatment, gradually cooling to 20° C. within 12 h; collecting the composite crystals formed after cooling by centrifugation to obtain 25.9 g of curcumin composite crystals;

[0076] (2) adding 70.5 g of polyoxyethylene (20) sorbitan monooleate to a vacuum stirring tank, and then adding the curcumin complex crystals collected in step (1), stirring and heating to 70-80° C. under a vacuum state of -0.8 MPa to completely dissolve the material until it becomes transparent; then continuing to heat to 120° C. and maintaining for 30 min, and then naturally cooling to room temperature to obtain a turmeric concentrate;

[0077] (3) Weigh 6.5 g of water and slowly add it to the cooled turmeric concentrate in step (2), stirring evenly to obtain a liquid curcumin product.

[0078] After testing, the curcumin content of the aqueous solution of turmeric product obtained in this embodiment is 17.3%, T680nm of 1% aqueous solution is 80.20%, the color tone of the aqueous solution is "lemon yellow", Abs is 1.0 color difference value (L=77.49, a=-4.57, b=59.25). Comparative Example 3 (the difference from Example 3 is that the secondary insulation temperature is too high)

[0079] (1) accurately weighing 19.7 g of curcumin, 1.2 g of ascorbyl palmitate, 0.8 g of mixed tocopherols and 5 g of sucrose fatty acid ester, adding them to 220 g of 95% (V / V) edible ethanol and stirring them evenly, heating them to 90° C. under stirring to completely dissolve the materials into a transparent state, and then keeping the temperature at this temperature for 2.5 h; starting to cool after the heat treatment, gradually cooling to 20° C. within 12 h; collecting the composite crystals formed after cooling by centrifugation to obtain 26.0 g of curcumin composite crystals;

[0080] (2) adding 67.0 g of polyoxyethylene (20) sorbitan monopalmitate into a vacuum stirring tank, and then adding the curcumin complex crystals collected in step (1), stirring and heating to 70-80° C. under a vacuum state of -0.8 MPa, so that the material is completely dissolved to a transparent state; then continuing to heat to 160° C. and maintaining for 30 min, and then naturally cooling to room temperature to obtain a turmeric concentrate;

[0081] (3) Weigh 6.5 g of water and slowly add it to the cooled turmeric concentrate in step (2), stirring evenly to obtain a liquid curcumin product.

[0082] After testing, the curcumin content of the liquid turmeric product obtained in this embodiment is 17.8%, the T680nm of the 1% aqueous solution is 83.01%, the hue of the aqueous solution is "yellow", and the color difference value Abs is 1.0 (L=85.32, a=-3.21, b=60.35).

[0083] Comparative Example 4 (the difference from Example 4 is that the secondary insulation time is too long)

[0084] (1) accurately weighing 19.7 g of curcumin, 1.2 g of ascorbyl palmitate, 0.8 g of mixed tocopherols and 5 g of sucrose fatty acid ester, adding them to 220 g of 95% (V / V) edible ethanol and stirring them evenly, heating them to 90° C. under stirring to completely dissolve the materials into a transparent state, and then keeping the temperature at this temperature for 2.5 h; starting to cool after the heat treatment, gradually cooling to 20° C. within 12 h; collecting the composite crystals formed after cooling by centrifugation to obtain 26.2 g of curcumin composite crystals;

[0085] (2) adding 53.1 g of polyoxyethylene (20) sorbitan monooleate to a vacuum stirring tank, and then adding the curcumin complex crystals collected in step (1), stirring and heating to 70-80° C. under a vacuum state of -0.8 MPa to completely dissolve the material until it becomes transparent; then continuing to heat to 145° C. and maintaining for 120 min, and then naturally cooling to room temperature to obtain a turmeric concentrate;

[0086] (3) Weigh 6.5 g of water and slowly add it to the cooled turmeric concentrate in step (2), stirring evenly to obtain a liquid curcumin product.

[0087] After testing, the curcumin content of the liquid turmeric product obtained in this embodiment is 18.9%, the T680nm of the 1% aqueous solution is 87.01%, the hue of the aqueous solution is "orange-yellow", and the color difference value of ABS is 1.0 (L=87.49, a=-2.01, b=61.14).

[0088] Effect Example

[0089] 1. Effect evaluation method

[0090] (1) Determination of solubility

[0091] The samples prepared in Examples 1 to 4 and Comparative Examples 1 to 4 were numbered in sequence, 0.1 g of each was weighed, a small amount of distilled water (i.e., neutral aqueous solution) was added and stirred, and after stirring evenly, the distilled water was added to 100 g, and after stirring evenly again, the solubility was judged according to the solution state (floating, dissolving, precipitating) after standing.

[0092] (2) Determination of color difference value

[0093] The samples prepared in Examples 1 to 4 and Comparative Examples 1 to 4 were numbered in sequence, 0.1 g of each was weighed, a small amount of distilled water was added and stirred, and after dissolution, the Abs of the solution was adjusted to 1.000 at λmax=425 nm, and the color difference value was measured using a colorimeter.

[0094] (3) Determination of light transmittance

[0095] The samples prepared in Examples 1 to 4 and Comparative Examples 1 to 4 were numbered in sequence, 0.1 g of each was weighed, a small amount of distilled water (i.e., neutral aqueous solution) was added and stirred, and after complete dissolution, the distilled water was added to 100 g, and the solution transmittance was measured at T680 nm.

[0096] (4) Light color stability

[0097] The samples prepared in Examples 1 to 4 and Comparative Examples 1 to 4 were numbered in sequence, and 0.1 g of each was weighed. A small amount of distilled water (i.e., a neutral aqueous solution) and acidic water (0.5 g of citric acid and 0.3 g of sodium citrate were dissolved in 500 g of distilled water to prepare an acidic aqueous solution with pH = 3.2) were added and stirred. After dissolution, the Abs of the solution was adjusted to 1.000 at λmax = 425 nm. After stirring evenly, 30 mL of each was poured into a plastic bottle and placed in a light box (temperature 37°C, light intensity: 22000 LUX). The color stability under light conditions was judged by observing the fading changes under the same time conditions.

[0098] 2. Effect evaluation results

[0099] (1) Dissolution stability

[0100] Figure 1 and Figure 2 The 1% solutions prepared from the samples prepared in Examples 1 to 4 and Comparative Examples 1 to 4 are shown in Table 1. After standing for 24 hours, no stratification or precipitation occurs in Examples 1 to 4, indicating that they have good water solubility. Although no stratification or precipitation occurs in Comparative Examples 1 to 4 after standing, the solutions become turbid.

[0101] (2) Solution color difference

[0102] from Figure 1 and Figure 2 By comparison, it can be seen that the color tone of the aqueous solution corresponding to Examples 1 to 4 changes from light yellow to orange-red, and the color tone of the aqueous solution corresponding to Comparative Examples 1 to 4 changes from greenish yellow to orange-yellow, and there is no orange-red color change.

[0103] The difference between Example 1 and Comparative Example 1 is the presence or absence of surfactant A. Compared with Example 1, the L and a* values ​​of the aqueous solution of Comparative Example 1 are smaller, that is, the color tone of Comparative Example 1 is darker and tends to be yellow-green.

[0104] The difference between Example 2 and Comparative Example 2 lies in the different types of antioxidants. As can be seen from Table 1, compared with the antioxidant composed of tea polyphenols and BHT, the water-soluble liquid curcumin corresponding to the antioxidant composed of ascorbyl palmitate and mixed tocopherols has larger L and a* values ​​in aqueous solution, that is, its color tone tends to be more reddish and brighter.

[0105] The difference between Example 3 and Comparative Example 3 is the difference in the secondary insulation temperature, and the difference between Example 4 and Comparative Example 4 is the difference in the secondary insulation time. It can be seen from Table 1 that the secondary insulation temperature is too high (Comparative Example 3) or the secondary insulation time is too long (Comparative Example 4), which will cause the degradation of curcumin, affect the caramelization reaction, and then affect the curcumin content in the final product and the color tone of its aqueous solution, and also affect the light transmittance of the aqueous solution. The aqueous solution corresponding to Example 3 and Example 4 obviously presents orange or orange red.

[0106] The above results show that the adjustment of technical parameters such as adding sucrose fatty acid esters, selecting appropriate antioxidants, increasing temperature, and extending heating time will change the color tone of curcumin and expand the color tone range of curcumin.

[0107] (3) Light transmittance

[0108] from Figure 1 , Figure 2 Compared with Table 1, it can be seen that the light transmittance of Examples 1 to 4 increases successively and is not affected by the change of color tone. The solutions of Comparative Examples 1 to 4 are relatively turbid and have low light transmittance.

[0109] (4) Color stability

[0110] Figure 3 and Figure 4 The results of the light color stability of the water-soluble liquid curcumin obtained in Examples 1 to 4 and Comparative Examples 1 to 4 in a neutral aqueous solution (pH=7.0) are shown in the figure. It can be seen from the figure that:

[0111] The color of the aqueous solution corresponding to Examples 1 to 4 remained the same as the initial color after 2 days of illumination, without fading; after 5 days of illumination, slight fading occurred, and the color of the sample became slightly darker.

[0112] The aqueous solutions corresponding to Comparative Examples 1 to 4 faded after 2 days of illumination, and the color of the samples faded significantly, and the degree of fading was significantly higher than the color degree of the water-soluble liquid curcumin prepared in Examples 1 to 4 after 5 days of illumination. The water-soluble liquid curcumin prepared in Comparative Examples 1-4 faded significantly after 3 days of illumination.

[0113] Figure 5 and Figure 6 The figure shows the light color stability results of the water-soluble liquid curcumin prepared in Examples 1 to 4 and Comparative Examples 1 to 4 in an acidic aqueous solution (pH=3.2).

[0114] The corresponding aqueous solutions of Examples 1 to 4 faded after 3 days of illumination, but the degree of fading was significantly lower than that of Comparative Examples 1 to 4 after 3 days of illumination. The degree of fading of the water-soluble liquid curcumin prepared in Comparative Examples 1-4 increased significantly after 3 days of illumination.

[0115] Table 1 Performance differences and effect statistics of examples and comparative examples

[0116]

[0117]

[0118] Note: The number of + represents the degree; + means low solubility and unstable color under light conditions; +++++ means high solubility and stable color under light conditions.

[0119] The above embodiments are preferred implementation modes of the present invention, but the implementation modes of the present invention are not limited to the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications that do not deviate from the spirit and principles of the present invention should be equivalent replacement methods and are included in the protection scope of the present invention.

Claims

1. A method for preparing a water-soluble liquid curcumin, characterized in that The following steps are included: (1) adding curcumin, antioxidant and surfactant A to ethanol and stirring evenly, heating the material under stirring until the material is completely dissolved into a transparent state, and then keeping the temperature at 85° C. to 95° C. for 0.5 h to 4 h; after the heat preservation treatment, slowly cooling until crystals precipitate, collecting the crystal precipitate, and obtaining curcumin complex crystals; (2) under vacuum, mixing surfactant B and the curcumin complex crystals collected in step (1), heating the mixture to completely dissolve the mixture until it becomes transparent, and then keeping the mixture at 80° C. to 150° C. for 10 to 100 minutes; and cooling the mixture to obtain a water-soluble turmeric concentrate; (3) adding the diluent to the water-soluble curcumin concentrate obtained in step (2) under stirring and stirring uniformly to obtain a water-soluble liquid curcumin; The surfactant A described in step (1) is at least one of sucrose fatty acid ester and sucrose acetate isobutyrate, The surfactant B described in step (2) is at least one of polyoxyethylene (20) sorbitan monolaurate, polyoxyethylene (20) sorbitan monopalmitate, polyoxyethylene (20) sorbitan monostearate, polyoxyethylene (20) sorbitan monooleate and polyglycerol fatty acid esters.

2. The method for preparing water-soluble liquid curcumin according to claim 1, wherein: The antioxidant described in step (1) is at least one of VC, sodium isoVC, ascorbyl palmitate, EGCG, VE, mixed tocopherols, TBHQ and BHA, and the amount of the antioxidant accounts for 0.001% to 5% of the quality of the water-soluble liquid curcumin.

3. The method for preparing water-soluble liquid curcumin according to claim 1, characterized in that: The dosage of the surfactant A accounts for 0.5% to 15% of the quality of the water-soluble liquid curcumin.

4. The method for preparing the water-soluble liquid curcumin according to claim 1, wherein: The mass content of the curcumin complex crystals in the water-soluble turmeric concentrated solution described in step (2) is 5% to 35%.

5. The method for preparing water-soluble liquid curcumin according to claim 1, characterized in that: The mass content of surfactant B in the water-soluble turmeric concentrated solution described in step (2) is 95% to 65%.

6. The method for preparing the water-soluble liquid curcumin according to claim 1, characterized in that: The vacuum condition described in step (2) is a vacuum degree of -0.06MPa to -0.1MPa.

7. The method for preparing the water-soluble liquid curcumin according to claim 1, characterized in that: The insulation condition described in step (2) is 140° C. to 145° C. for 30 min to 45 min.

8. The method for preparing the water-soluble liquid curcumin according to claim 1, characterized in that: The diluent described in step (3) is at least one of water, glycerol, ethanol and propylene glycol, and the amount of the diluent is 0.001% to 20% of the mass of the water-soluble turmeric concentrate.

9. A water-soluble liquid curcumin, characterized in that The method is obtained by the preparation method according to any one of claims 1 to 8.

10. Use of the water-soluble liquid curcumin according to claim 9 in the field of food, medicine or cosmetics.

Images