Method for improving color stability of phycocyanin, phycocyanin-polysaccharide compound and application of phycocyanin-polysaccharide compound

Abstract

The invention discloses a method for improving the color stability of phycocyanin, a phycocyanin-polysaccharide compound and application of the phycocyanin-polysaccharide compound, the prepared compound product presents the specific blue color of the phycocyanin, the color of a solution is obviously improved compared with that of single phycocyanin in an acid environment, and the pigment retention rate is obviously increased. The advantages of high coloring power and high functional activity of phycocyanin are reserved, the used raw materials are free of toxic and harmful reagents and are all food-grade raw materials, the preparation method is green and mild, special processing equipment such as high temperature and high pressure is not needed, and expanded production is easy. The invention not only solves the defect that the phycocyanin is easy to turn green under the acidic condition in the production and processing process, but also solves the technical problems of low action efficiency, low safety and difficulty in large-scale production in the aspect of improving the acid stability of the phycocyanin.

Description

Technical Field

[0001] The invention belongs to the technical field of food processing, and in particular relates to a method for improving the color stability of phycocyanin, a phycocyanin-polysaccharide complex and an application thereof. Background Art

[0002] Phycocyanin is a natural edible blue pigment protein with good water solubility. It also has physiological activities such as antioxidant, anti-inflammatory, anti-tumor and immunomodulatory activities. It has broad application prospects in the fields of food, medicine and skin care products.

[0003] However, the acid-base stability of phycocyanin is not high and it is sensitive to pH changes. Phycocyanin is relatively stable in weak acid (pH5-7), turns green in high acid (pH<4), and is prone to precipitation. It is easy to fade under alkaline conditions. However, the pH of current beverages is mostly acidic, so the application of phycocyanin is greatly limited. It is now mainly used in instant cold drinks or freshly made cold drinks that do not involve long-term storage. Therefore, improving the color acid stability of phycocyanin is of practical significance for its practical application.

[0004] Adding stabilizers is the simplest way to improve the stability of phycocyanin. This method is easy to apply and does not require complex or expensive equipment, but requires the stabilizer to be highly safe, low-toxic and harmless, and the added amount is large. At present, the commonly used stabilizers are mainly some small molecules, such as glucose, sucrose, fructose, sorbitol, glycerol, etc. The protective effect of these stabilizers increases with the increase of concentration. In order to achieve the protective effect, the content of these stabilizers needs to reach 20% to 50%, but extremely high addition amounts will increase its viscosity, and it is only suitable as a colorant for food matrices such as hard candies, but not for liquid beverages.

[0005] In addition, studies have shown that polysaccharides can be used to stabilize proteins from damage in low-acid environments. Polysaccharides bind to proteins through electrostatic attraction and hydrophobic interactions to stabilize their conformation. As a special pigment protein, if a polysaccharide can be found to form a non-covalent bond with phycocyanin to protect the polymer structure of phycocyanin, the blue color of phycocyanin can be stabilized to prevent it from turning green at low pH values. This is undoubtedly of great significance for the widespread use of phycocyanin in the food industry. Summary of the invention

[0006] The purpose of this section is to summarize some aspects of embodiments of the present invention and briefly introduce some preferred embodiments. Some simplifications or omissions may be made in this section and the specification abstract and the invention title of this application to avoid blurring the purpose of this section, the specification abstract and the invention title, and such simplifications or omissions cannot be used to limit the scope of the present invention.

[0007] In view of the above problems and / or the problems existing in the prior art, the present invention is proposed.

[0008] Therefore, the purpose of the present invention is to overcome the deficiencies in the prior art and provide a method for improving the color stability of phycocyanin.

[0009] In order to solve the above technical problems, the present invention provides the following technical solutions: comprising:

[0010] Phycocyanin is dissolved in deionized water and stirred until fully and evenly hydrated to obtain a phycocyanin solution;

[0011] The anionic polysaccharide is dissolved in deionized water and stirred until fully and evenly hydrated to obtain a polysaccharide solution;

[0012] The phycocyanin solution and the polysaccharide solution are mixed and stirred to obtain a phycocyanin-polysaccharide composite solution. After adjusting the pH to acidic, stirring is continued at low temperature to generate a phycocyanin-polysaccharide complex, thereby achieving improvement in the color stability of the phycocyanin.

[0013] As a preferred embodiment of the method for improving the color stability of phycocyanin according to the present invention, the anionic polysaccharide comprises one of kappa carrageenan, tau carrageenan, sodium carboxymethyl cellulose and xanthan gum, wherein the sodium carboxymethyl cellulose comprises sodium carboxymethyl cellulose with a degree of substitution of 0.7. 0.7 Or sodium carboxymethyl cellulose with a degree of substitution of 1.2 1.2 .

[0014] Among them, sodium carboxymethyl cellulose (CMC for short) is a kind of high polymer fiber ether obtained by chemical modification of natural cellulose. Its structure is mainly composed of D-glucose units connected by β (1→4) glycosidic bonds. Its main reaction is: natural cellulose first undergoes alkalization reaction with NaOH, and with the addition of chloroacetic acid, the hydrogen on the hydroxyl group on its glucose unit undergoes substitution reaction with the carboxylmethyl group in chloroacetic acid. From the structural formula, it can be seen that there are 3 hydroxyl groups on each glucose unit, namely C2, C3, and C6 hydroxyl groups. The degree of substitution of hydrogen on the hydroxyl group of the glucose unit is expressed by the degree of substitution. The degree of substitution of CMC directly affects the solubility, emulsification, thickening, stability, acid resistance and salt resistance of CMC.

[0015] As a preferred embodiment of the method for improving the color stability of phycocyanin of the present invention, the mass concentration of the phycocyanin solution is 0.5-1.5%, and the mass concentration of the polysaccharide solution is 0.5-1.5%.

[0016] As a preferred embodiment of the method for improving the color stability of phycocyanin of the present invention, the ratio of phycocyanin to polysaccharide in the phycocyanin-polysaccharide composite solution is 4 to 1:1.

[0017] As a preferred embodiment of the method for improving the color stability of phycocyanin of the present invention, the stirring time of dissolving the phycocyanin in deionized water is 12 to 24 hours, and the stirring temperature is 4 to 25°C.

[0018] As a preferred embodiment of the method for improving the color stability of phycocyanin of the present invention, the stirring time of the anionic polysaccharide dissolved in deionized water is 12 to 24 hours, and the stirring temperature is 4 to 25°C.

[0019] As a preferred embodiment of the method for improving the color stability of phycocyanin according to the present invention, the step of adjusting the pH to acidic is adjusting the pH to 3-4.

[0020] As a preferred embodiment of the method for improving the color stability of phycocyanin of the present invention, the time for continuing low-temperature stirring is 15 to 30 minutes, and the stirring temperature is 4 to 25°C.

[0021] Another object of the present invention is to provide a phycocyanin-polysaccharide complex, wherein the phycocyanin-polysaccharide complex has an improved pigment retention rate in an acidic environment compared to phycocyanin.

[0022] Another object of the present invention is to provide a phycocyanin-polysaccharide complex for use as a natural edible blue pigment protein in a food matrix.

[0023] Beneficial effects of the present invention:

[0024] The composite product prepared by the present invention has a blue color that is unique to phycocyanin. The color of the solution in an acidic environment is significantly improved compared to that of a single phycocyanin, and the pigment retention rate is significantly improved. The present invention retains the advantages of strong tinting power and strong functional activity of phycocyanin. The raw materials used are free of toxic and harmful reagents and are all food-grade raw materials. The preparation method is green and mild, and does not require special processing equipment such as high temperature and high pressure, and is easy to expand production. The present invention not only solves the defect that phycocyanin is easy to turn green under acidic conditions during production and processing, but also solves the technical problems of low efficiency, low safety, and difficulty in large-scale production in improving the acid stability of phycocyanin.

[0025] The present invention can improve the color stability of phycocyanin, so that phycocyanin can maintain its blue color in an acidic environment. The method is simple and easy to apply, has high safety, and a small amount of addition does not affect the original sensory properties of food. It can be applied to a variety of food matrices, expanding the application range of phycocyanin in the food industry. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for describing the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative labor. Among them:

[0027] Figure 1 The following is a comparison chart of the actual color changes of the products of Examples 1 to 4 and Comparative Examples 1 and 2.

[0028] Figure 2 The following is a comparison of the resuspension effects of the products of Example 1, Example 2 and Comparative Example 1 after sedimentation.

[0029] Figure 3 The figure is a comparison of the changes in pigment retention rates of the products of Examples 1 to 4 and Comparative Example 1.

[0030] Figure 4 The following is a comparison of the changes in the UV spectra of the products of Examples 1 to 4 and Comparative Examples 1 and 2.

[0031] Figure 5 It is a comparison chart of the changes in chromaticity L* of the products of Examples 1 to 4 and Comparative Example 1.

[0032] Figure 6 A comparison chart of the changes in chromaticity a* of the products of Examples 1 to 4 and Comparative Example 1

[0033] Figure 7 The comparison diagram of the chromaticity b* of the products of Examples 1 to 4 and Comparative Example 1 is shown in FIG.

[0034] Figure 8 It is a comparison chart of the microstructure changes of the products of Examples 1 to 4 and Comparative Example 12.

[0035] Fig. 9 This is a comparison chart of the color changes of phycocyanin-polysaccharide complexes in different proportions in Example 13.

[0036] Fig.10 It is a comparison diagram of the complexes formed by different types of polysaccharides in Examples 1 to 4 and Comparative Examples 1 and 5 to 8. DETAILED DESCRIPTION

[0037] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the specific implementation methods of the present invention are described in detail below in conjunction with the embodiments of the specification.

[0038] In the following description, many specific details are set forth to facilitate a full understanding of the present invention, but the present invention may also be implemented in other ways different from those described herein, and those skilled in the art may make similar generalizations without violating the connotation of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0039] Secondly, the term "one embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The term "in one embodiment" that appears in different places in this specification does not necessarily refer to the same embodiment, nor does it refer to a separate or selective embodiment that is mutually exclusive with other embodiments.

[0040] Unless otherwise specified, the raw materials used in the present invention are all commercially available in the art. Among them, phycocyanin was purchased from Zhejiang Binmei Co., Ltd. with a specification of E30 and a purity of phycocyanin ≧0.7.

[0041] The present invention adopts the following method to detect each index:

[0042] Detect the color of the sample:

[0043] The color analysis was performed using the CIELab colorimetric system and the spectrophotometer was used for measurement. * Indicates the brightness of the solution. The value is negatively correlated with the color depth. a* indicates the redness of the solution (+a * ) and greenness value (-a * ), b * Indicates yellowness value (+b * ) and blue value (-b * ), where b * The larger the value, the * The higher the blue value of the C-phycocyanin solution, the higher the blue value of the C-phycocyanin solution.

[0044] UV-Vis absorption spectrum:

[0045] Take a sample and dilute it appropriately, place it under a 1 cm light path, scan its wavelength in the wavelength range of 200-700 nm, and obtain the UV-visible absorption spectrum.

[0046] Pigment retention rate:

[0047] The color stability of the sample is evaluated by the pigment retention rate, and the change of the maximum absorbance value of the sample solution in the visible light region is monitored. The UV-visible absorption spectrum is measured by double light paths with the sample solvent as the control each time, and the light path is 1 cm. The pigment retention rate is calculated according to the following formula:

[0048] Pigment retention rate (%) = A / A0×100%

[0049] Wherein, A0 represents the maximum absorbance value of C-phycocyanin during the initial measurement, and A represents the final absorbance value.

[0050] Particle size and net charge:

[0051] Particle size was measured by laser diffraction. The samples were mixed thoroughly and then dispersed into the instrument's sample cell with uniform stirring until a 5% haze level was reached. The pH of the dispersant water was adjusted to match that of the sample; the refractive index of the dispersant was 1.330 and that of the sample was 1.345. D was recorded. [4,3] and D 50 The particle size distribution and zeta potential were measured using ZetaPALS produced by Brookhaven Instruments, USA.

[0052] Microstructural changes:

[0053] The samples were freeze-dried and the microstructure was observed using a scanning electron microscope (SEM).

[0054] Example 1

[0055] This embodiment provides a method for improving the color stability of phycocyanin, wherein the pH of the phycocyanin-polysaccharide composite solution is 3.5, specifically:

[0056] 1) dissolving phycocyanin in deionized water, stirring at 300 rpm at room temperature until fully and evenly hydrated, to obtain a phycocyanin solution with a mass concentration of 1%;

[0057] 2) Dissolving kappa carrageenan in deionized water, stirring at 300 rpm at room temperature until fully and evenly hydrated, to obtain a polysaccharide solution with a mass concentration of 1%;

[0058] 3) The phycocyanin solution and the polysaccharide solution were mixed in a mass ratio of 4:1 between phycocyanin and polysaccharide, and stirred at 300 rpm for 30 min to obtain a phycocyanin-polysaccharide composite solution. The pH was adjusted to 3.5 and then stirred at low temperature for 30 min to produce the phycocyanin-polysaccharide complex of this embodiment, recorded as κCG-PC, to achieve improvement in the color stability of phycocyanin.

[0059] Example 2

[0060] The difference between this embodiment and embodiment 1 is that tau carrageenan is used as the anionic polysaccharide, and the remaining steps are the same as those of embodiment 1, so as to obtain the phycocyanin-polysaccharide complex of this embodiment, which is recorded as tau CG-PC.

[0061] Example 3

[0062] The difference between this embodiment and embodiment 1 is that the anionic polysaccharide is sodium carboxymethyl cellulose (CMC) with a degree of substitution of 0.7.0.7 ), and the remaining steps were all referred to Example 1 to obtain the phycocyanin-polysaccharide complex of this example, which was recorded as CMC 0.7 -PC.

[0063] Example 4

[0064] The difference between this embodiment and embodiment 1 is that the anionic polysaccharide is sodium carboxymethyl cellulose (CMC) with a degree of substitution of 1.2. 1.2 ), and the remaining steps were all referred to Example 1 to obtain the phycocyanin-polysaccharide complex of this example, which was recorded as CMC 1.2 -PC.

[0065] Comparative Example 1

[0066] The difference between this comparative example and Example 1 is that only a phycocyanin solution is prepared, the pH is adjusted to 3.5, and a phycocyanin solution is obtained, which is recorded as PC pH 3.5 and is stored at 4° C. in the dark.

[0067] Comparative Example 2

[0068] The difference between this comparative example and Example 1 is that only a phycocyanin solution is prepared, and the pH is adjusted to 7 to obtain a phycocyanin solution, which is recorded as PC pH7 and stored at 4°C in the dark.

[0069] Figure 1 The color change comparison diagram of the products of Examples 1 to 4 and Comparative Examples 1 and 2, wherein a represents PC pH 7, b represents PC pH 3.5, c represents κCG-PC, d represents τCG-PC, and e represents CMC 0.7 -PC,f represents CMC 1.2- PC, from Figure 1 It can also be clearly seen that when the phycocyanin environment changes from neutral to acidic, the system tends to turn green. After the complex is formed, compared with single phycocyanin, the blue preservation of the κCG-PC complex is the best.

[0070] Figure 2 The results of the resuspension after sedimentation of the products of Example 1, Example 2 and Comparative Example 1 show that the blue color of the κCG-PC complex is still maintained after resuspension. The sample with a mass ratio of phycocyanin to κ carrageenan of 4:1 is first precipitated and then suspended. Compared with the single phycocyanin solution, its blue protection effect is better, which fully demonstrates the protective effect of κ carrageenan on the color of phycocyanin at this ratio.

[0071] Figure 3The comparison of the changes in the pigment retention rates of the products of Examples 1 to 4 and Comparative Example 1 shows that after complexing with polysaccharides, the changes in the pigment retention rates of κCG-PC, τCG-PC complexes and phycocyanin follow a similar pattern, indicating that the addition of carrageenan does not interfere much with the pigment retention rate, while the addition of other polysaccharides significantly reduces the pigment retention rate, resulting in greater interference.

[0072] Figure 4 The UV-visible spectra of the products of Examples 1 to 4 and Comparative Examples 1 and 2 are compared. Among the phycocyanin-polysaccharide complexes, the UV-visible spectra of the κCG-PC complex and the single phycocyanin at 620 nm are the closest, indicating that the addition of κ carrageenan has the least interference with the absorption of phycocyanin tetrapyrrole at 620 nm.

[0073] Figures 5 to 7 The changes in chromaticity L*, a*, and b* of the products of Examples 1 to 4 and Comparative Example 1 are compared. The brightness L value is not much different. The a* value of κCGPC is similar to that of PC. The b* value of κCGPC is the most negative, indicating that it has the best protection against blue. Figure 1 , Figure 2 , Fig. 9 The apparent observation results are consistent.

[0074] Figure 8 The microstructure change comparison diagram of the products of Examples 1 to 4 and Comparative Examples 1 and 2, wherein a represents PC pH 7, b represents PC pH 3.5, c represents κCG-PC, d represents τCG-PC, and e represents CMC 0.7 -PC,f represents CMC 1.2- PC. It can be seen from the figure that the surface of phycocyanin particles will produce obvious shrinkage and even cracks after acidification, while the surface of the particles will be more relaxed and smooth after forming the κCG-PC complex, which shows that this method has a certain protective effect on phycocyanin.

[0075] Example 5

[0076] This embodiment provides a method for improving the color stability of phycocyanin, wherein the pH of the phycocyanin-polysaccharide composite solution is 3, specifically:

[0077] 1) dissolving phycocyanin in deionized water and stirring until fully and evenly hydrated to obtain a phycocyanin solution;

[0078] 2) Dissolving kappa carrageenan in deionized water and stirring until fully and evenly hydrated to obtain a polysaccharide solution;

[0079] 3) The phycocyanin solution and the polysaccharide solution were mixed in a ratio of 4:1 and stirred at 300 rpm for 30 min to obtain a phycocyanin-polysaccharide composite solution. After adjusting the pH to 3, stirring was continued at low temperature for 30 min to produce the phycocyanin-polysaccharide complex of this embodiment, thereby improving the color stability of phycocyanin.

[0080] Example 6

[0081] The difference between this embodiment and embodiment 5 is that tau carrageenan is used as the anionic polysaccharide, and the remaining steps are the same as those of embodiment 5 to obtain the phycocyanin-polysaccharide complex of this embodiment.

[0082] Example 7

[0083] The difference between this embodiment and embodiment 5 is that the anionic polysaccharide is sodium carboxymethyl cellulose (CMC) with a degree of substitution of 0.7. 0.7 ), and the remaining steps are all referred to Example 5 to obtain the phycocyanin-polysaccharide complex of this example.

[0084] Example 8

[0085] The difference between this embodiment and embodiment 5 is that the anionic polysaccharide is sodium carboxymethyl cellulose (CMC) with a degree of substitution of 1.2. 1.2 ), and the remaining steps are all referred to Example 5 to obtain the phycocyanin-polysaccharide complex of this example.

[0086] Comparative Example 3

[0087] The difference between this comparative example and Example 5 is that only the phycocyanin solution is prepared, the pH is adjusted to 3.5, and the obtained phycocyanin solution is stored at 4° C. in the dark.

[0088] Example 9

[0089] This embodiment provides a method for improving the color stability of phycocyanin, wherein the pH of the phycocyanin-polysaccharide composite solution is 4, specifically:

[0090] 1) dissolving phycocyanin in deionized water and stirring until fully and evenly hydrated to obtain a phycocyanin solution;

[0091] 2) Dissolving kappa carrageenan in deionized water and stirring until fully and evenly hydrated to obtain a polysaccharide solution;

[0092] 3) The phycocyanin solution and the polysaccharide solution were mixed in a ratio of 4:1 and stirred at 300 rpm for 30 min to obtain a phycocyanin-polysaccharide composite solution. The pH was adjusted to 4 and then stirred at low temperature for 30 min to produce the phycocyanin-polysaccharide complex of this embodiment, thereby improving the color stability of phycocyanin.

[0093] Example 10

[0094] The difference between this embodiment and embodiment 9 is that tau carrageenan is used as the anionic polysaccharide, and the remaining steps are the same as those of embodiment 9 to obtain the phycocyanin-polysaccharide complex of this embodiment.

[0095] Embodiment 11

[0096] The difference between this embodiment and embodiment 9 is that the anionic polysaccharide is sodium carboxymethyl cellulose (CMC) with a degree of substitution of 0.7. 0.7 ), and the remaining steps are referred to Example 9 to obtain the phycocyanin-polysaccharide complex of this example.

[0097] Example 12

[0098] The difference between this embodiment and embodiment 9 is that the anionic polysaccharide is sodium carboxymethyl cellulose (CMC) with a degree of substitution of 1.2. 1.2 ), and the remaining steps are referred to Example 9 to obtain the phycocyanin-polysaccharide complex of this example.

[0099] Comparative Example 4

[0100] The difference between this comparative example and Example 9 is that only the phycocyanin solution is prepared, the pH is adjusted to 4, and the obtained phycocyanin solution is stored at 4° C. in the dark.

[0101] The phycocyanin-polysaccharide complexes or phycocyanin of Examples 1 to 12 and Comparative Examples 1 to 4 were collected, diluted 100 times with deionized water, and the particle size, PDI and zeta potential were measured using a nano-laser particle size detector. The results are shown in Table 1.

[0102] Table 1

[0103]

[0104] Generally speaking, the smaller the size of the colloidal particles in the solution, the higher the absolute value of the zeta potential and the more stable it is. It can be seen from Table 1 that in an acidic environment, compared with pure phycocyanin, the particle size of the phycocyanin-polysaccharide complex of the present application is increased, but among them, the particle size of the complex formed by κ carrageenan and phycocyanin is the smallest and the particle size of the complex is the smallest when the pH is 3.5, the zeta potential is relatively high, the complex is more uniform, the resuspension effect of the subsequent solution will be better, and the solution will be more stable. Referring to the actual picture, it can also be found that the blue color protection effect of the solution is better at this time.

[0105] Example 13

[0106] This example is used to explore the effects of different ratios of phycocyanin and polysaccharide on the properties of the prepared composite. Specifically, the mass ratio of phycocyanin and polysaccharide in step 3) of Example 1 was adjusted to 2:1, 1:1, and 6:1 to obtain phycocyanin-polysaccharide composites with different ratios of phycocyanin and polysaccharide in this example. The relevant indicators of the composites were tested and compared with those in Example 1. The results are shown in Table 2 and Table 3. Fig. 9 shown.

[0107] Table 2

[0108]

[0109] Table 2 lists the particle size and zeta potential of the complex formed by different ratios of phycocyanin and κ carrageenan. When the ratio of phycocyanin to κ carrageenan is low, the blue protection of the system is good, but the ratio of phycocyanin to κ carrageenan cannot be too low.

[0111] Fig. 9 The color changes of phycocyanin-polysaccharide complexes of different ratios at pH 3.5 in this example are compared. Among them, a represents PC pH 3.5, b represents PC-κCG mass ratio 1:1, c represents PC-κCG mass ratio 2:1, d represents PC-κCG mass ratio 4:1, and e represents PC-κCG mass ratio 6:1. Fig. 9 In the embodiment, when the mass ratio of phycocyanin to κ carrageenan is 6:1, the blue color has a tendency to fade significantly compared with that of 4:1. Therefore, the ratio of phycocyanin to κ carrageenan is 4:1, and the particle size of the complex is relatively small. At the same time, the zeta potential results show that if the ratio of κ carrageenan is too high, the electronegativity of the complex will be negative, and if the ratio of κ carrageenan is too high, the color of the complex liquid will turn to green. Therefore, the sample complex prepared in Example 5 has the best blue retention effect.

[0112] Comparative Example 5

[0113] The difference between this comparative example and Example 1 is that the type of polysaccharide is adjusted to chondroitin sulfate, and the rest of the preparation process is the same as Example 1, to obtain the phycocyanin-polysaccharide complex of this comparative example, which is recorded as chondroitin sulfate-PC.

[0114] Comparative Example 6

[0115] The difference between this comparative example and Example 1 is that the type of polysaccharide is adjusted to xanthan gum, and the rest of the preparation process is the same as Example 1, to obtain the phycocyanin-polysaccharide complex of this comparative example, which is recorded as xanthan gum-PC.

[0116] Comparative Example 7

[0117] The difference between this comparative example and Example 1 is that the type of polysaccharide is adjusted to chitosan, and the rest of the preparation process is the same as Example 1, to obtain the phycocyanin-polysaccharide complex of this comparative example, which is recorded as chitosan-PC.

[0118] Comparative Example 8

[0119] The difference between this comparative example and Example 1 is that the type of polysaccharide is adjusted to pectin, and the rest of the preparation process is the same as Example 1, to obtain the phycocyanin-polysaccharide complex of this comparative example, which is recorded as pectin-PC.

[0120] Fig.10 Comparison diagram of the complexes formed with different types of polysaccharides in Examples 1 to 4 and Comparative Examples 1, 5 to 8, a represents κCG-PC, b represents τCG-PC, and c represents CMC 0.7 -PC, d represents CMC 1.2 -PC, e represents chondroitin sulfate-PC, f represents xanthan gum-PC, g represents chitosan-PC, h represents pectin-PC, i represents PC pH 3.5, from Fig.10 It can be seen that the blue protection effect of the PC-κCG complex is the most obvious, and the other examples also have good protection effects, while the blue retention rate of the complexes prepared by selecting other types of polysaccharides in Comparative Examples 5 to 8 is significantly reduced.

[0121] In summary, the composite product obtained by the method for improving the color stability of phycocyanin provided by the present invention is blue, which is unique to phycocyanin. The solution has a significant improvement in color under an acidic environment compared to a single phycocyanin, and the pigment retention rate is significantly improved. In addition, the present invention retains the advantages of strong tinting power and strong functional activity of phycocyanin. The raw materials used are free of toxic and harmful reagents, and are all food-grade raw materials. The preparation method is green and mild, and does not require special processing equipment such as high temperature and high pressure, and is easy to expand production. The present invention not only solves the defect that phycocyanin is easy to turn green under acidic conditions during production and processing, but also solves the technical problems of low efficiency, low safety, and difficulty in large-scale production in improving the acid stability of phycocyanin.

[0122] The present invention can improve the color stability of phycocyanin, so that phycocyanin can maintain its blue color in an acidic environment. The method is simple and easy to apply, has high safety, and a small amount of addition does not affect the original sensory properties of food. It can be applied to a variety of food matrices, expanding the application range of phycocyanin in the food industry.

[0123] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the spirit and scope of the technical solutions of the present invention, which should all be included in the scope of the claims of the present invention.

Claims

1. A method for improving the color stability of phycocyanin, characterized in that: include, Phycocyanin is dissolved in deionized water and stirred until fully and evenly hydrated to obtain a phycocyanin solution; The anionic polysaccharide is dissolved in deionized water and stirred until fully and evenly hydrated to obtain a polysaccharide solution; The phycocyanin solution and the polysaccharide solution are mixed and stirred to obtain a phycocyanin-polysaccharide composite solution. After adjusting the pH to acidic, stirring is continued at low temperature to generate a phycocyanin-polysaccharide complex, thereby achieving improvement in the color stability of the phycocyanin.

2. The method for improving the color stability of phycocyanin according to claim 1, characterized in that: The anionic polysaccharide includes one of kappa carrageenan, tau carrageenan, sodium carboxymethyl cellulose and xanthan gum, wherein the sodium carboxymethyl cellulose includes sodium carboxymethyl cellulose with a degree of substitution of 0.

7. 0.7 Or sodium carboxymethyl cellulose with a degree of substitution of 1.2 1.2 .

3. The method for improving the color stability of phycocyanin according to claim 1, characterized in that: The mass concentration of the phycocyanin solution is 0.5-1.5%, and the mass concentration of the polysaccharide solution is 0.5-1.5%.

4. The method for improving the color stability of phycocyanin according to claim 1, characterized in that: The ratio of phycocyanin to polysaccharide in the phycocyanin-polysaccharide composite solution is 4 to 1:

1.

5. The method for improving the color stability of phycocyanin according to claim 1, characterized in that: The stirring time of dissolving the phycocyanin in deionized water is 12 to 24 hours, and the stirring temperature is 4 to 25°C.

6. The method for improving the color stability of phycocyanin according to claim 1, characterized in that: The stirring time of the anionic polysaccharide dissolved in deionized water is 12 to 24 hours, and the stirring temperature is 4 to 25°C.

7. The method for improving the color stability of phycocyanin according to claim 1, characterized in that: The step of adjusting the pH to acidic is adjusting the pH to 3-4.

8. The method for improving the color stability of phycocyanin according to claim 1, characterized in that: The time for continuing low-temperature stirring is 15 to 30 minutes, and the stirring temperature is 4 to 25°C.

9. The phycocyanin-polysaccharide complex prepared by the method of claims 1 to 8, characterized in that: The pigment retention rate of the phycocyanin-polysaccharide complex is improved compared with phycocyanin in an acidic environment.

10. Use of the phycocyanin-polysaccharide complex as claimed in claim 9 as a natural edible blue pigment protein in a food matrix.

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