Compound for improving illumination storage stability of phycocyanin and preparation method thereof

Abstract

The invention belongs to the technical field of food processing, and particularly relates to a compound capable of improving illumination storage stability of phycocyanin and a preparation method of the compound. The compound is prepared from phycocyanin and zein through an anti-solvent precipitation method, the particle size range is 108-345 nm, the main secondary structure of the phycocyanin is reserved, and the specific blue hue and fluorescence characteristics of the phycocyanin can be maintained after continuous illumination storage at 25 DEG C for 28 days. The preparation method is simple, and the protein is composed of two natural proteins and is high in safety. On one hand, the problem that the phycocyanin easily loses the blue hue under illumination storage is solved, and on the other hand, the technical problem that the phycocyanin product can only be stored in a cold storage mode or applied to high-sugar food generally is solved.

Description

Technical Field

[0001] The invention relates to the technical field of food processing, in particular to a composite for improving the light storage stability of phycocyanin and a preparation method thereof. Background Art

[0002] Phycocyanin belongs to the phycobiliprotein family and is a rare edible natural blue pigment in nature. It is mainly extracted from cyanobacteria, especially Spirulina. It is composed of apolipoprotein and chromophore. Apolipoprotein monomers are composed of α-subunits and β-subunits. Monomers (αβ) can assemble into trimers ((αβ)3) and then form hexamers ((αβ)6). The chromophore, also known as phycocyanobilin, is an open-chain tetrapyrrole structure attached to apolipoprotein via a thioether bond, giving phycocyanin a bright blue color.

[0003] As a natural blue colorant, phycocyanin has been approved by my country's "GB2760-2014 Food Additives Usage Standard" as a colorant for frozen drinks (except edible ice), candies, spices and powders, fruit and vegetable juice (pulp) drinks, flavored drinks and jelly foods, and has a wide range of applications. Phycocyanin can not only be added to food, but also used in the production of cosmetics, such as eyeliner, eye shadow, etc. In addition, phycocyanin also has very rich physiological functions, including antioxidant, anti-inflammatory, anti-cancer, and anti-tumor, so it has broad application prospects in the food industry and the medical field;

[0004] Phycocyanin is sensitive to light and easily loses its color when exposed to light. The reason why phycocyanin is unstable under light is related to the light-capturing function in algae. After natural phycocyanin transfers energy to the photosystem, the damaged phycocyanin is constantly regenerated, while the phycocyanin extracted from algae is non-regenerative, causing its stability to be affected by light. When products with added phycocyanin use colorless and transparent packaging materials such as polyethylene terephthalate (PET) to highlight the blue hue to attract consumers, the phycocyanin will be exposed to light during the production and sales process, thus affecting its color stability;

[0005] The main ways to improve the stability of phycocyanin are to add stabilizers and preservatives, to encapsulate phycocyanin through delivery systems such as liposomes and nanoparticles, and to modify phycocyanin. Directly adding stabilizers and preservatives is the simplest and most convenient method, but stabilizers are generally small molecule sugars such as glucose and sucrose and require a higher addition amount, which will increase the viscosity of the food and make it more suitable for candy foods. In this case, using nano-scale delivery systems such as nanoemulsions and nanoparticles to improve the stability of phycocyanin will further expand the practical application range of phycocyanin. However, the existing delivery systems focus more on improving the physiological activity of phycocyanin and its instability under acidic and high temperature conditions.

[0006] Therefore, it is necessary to develop a complex that can improve the photostability of phycocyanin, reduce the color loss of phycocyanin under light exposure through the interaction between phycocyanin and zein, improve the stability of phycocyanin, enable it to be widely used in various foods, and provide new ideas for the stabilization of phycocyanin. Summary of the invention

[0007] The object of the present invention is to provide a composite for improving the light storage stability of phycocyanin and a preparation method thereof, so as to solve the problems raised in the above background technology.

[0008] To achieve the above object, the present invention provides the following technical solution: Step 1: dissolving phycocyanin in pure water, stirring for 30 minutes in a dark environment, and obtaining a phycocyanin solution with a concentration of 0.8 mg / mL;

[0009] Step 2: Dissolve zein in 70% ethanol and stir overnight to obtain a zein solution with a concentration range of 0.8 mg / mL to 7.2 mg / mL. Zein is insoluble in water due to its high proportion of hydrophobic amino acid residues. When the solvent environment becomes hydrophilic, driven by non-covalent interactions such as hydrogen bonds and hydrophobic interactions, zein will self-assemble to form spherical, rod-shaped and sheet-like structures.

[0010] Step 3: Add the zein solution to the phycocyanin solution using a syringe, stir for 30 minutes in a dark environment, and obtain a mixed solution with a mass ratio of phycocyanin to zein of 3:1 to 1:3;

[0011] Step 4: remove ethanol from the mixed solution of phycocyanin and zein by rotary evaporation, and add an equal volume of pure water to obtain a phycocyanin-zein complex.

[0012] Furthermore, in step 1 and step 2, the volume ratio of the phycocyanin concentration to the zein solution is 3:1.

[0013] Furthermore, the stirring in step 1, step 2 and step 3 is magnetic stirring, and the rotation speed is 600 rpm.

[0014] Furthermore, in step 4, the rotary evaporation temperature is 40°C.

[0015] Furthermore, the phycocyanin-zein complex obtained in step 4 is placed in a light incubator for light storage stability determination, the temperature is set to 25° C., and the light is continuously irradiated for 24 hours.

[0016] The phycocyanin-zein complex prepared by the method is spherical, and the zein encapsulates the phycocyanin inside to resist light exposure during storage, thereby improving the light stability of the phycocyanin.

[0017] The present invention has at least the following beneficial effects:

[0018] 1. The complex of the present invention retains the blue hue of phycocyanin, and the phycocyanin and zein are self-assembled to form a complex by an anti-solvent precipitation method, and the phycocyanin is coated inside by the zein. During the light storage period of up to 28 days, the phycocyanin-zein complex can maintain the color stability of phycocyanin.

[0019] 2. The preparation method of the present invention is simple and the raw materials are safe. The raw materials used are two natural proteins, and no toxic or harmful reagents are used. The complex can be added into a variety of food matrices such as food stored at room temperature and liquid beverages. The color storage stability is high and the effect on the sensory quality of the product is small, which expands the application scope of phycocyanin as a natural pigment in the food industry. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 is the sodium dodecyl sulfate-polyacrylamide gel electrophoresis diagram of phycocyanin-zein complex;

[0021] Figure 2 is the initial fluorescence spectrum of the phycocyanin-zein complex; wherein panel a is the fluorescence spectrum at an excitation wavelength of 280 nm; panel b is the fluorescence spectrum at an excitation wavelength of 580 nm;

[0022] Figure 3 is the Fourier transform infrared spectrum of the phycocyanin-zein complex;

[0023] Figure 4 is a scanning electron micrograph of the phycocyanin-zein complex;

[0024] Figure 5 The visual changes and color differences of the phycocyanin-zein complex before and after storage; the a-panel is the visual changes before and after light storage; the b-panel is the color difference changes before and after light storage;

[0025] Figure 6 The fluorescence spectra of the phycocyanin-zein complex after storage; Panel a is the fluorescence spectrum at an excitation wavelength of 280 nm; Panel b is the fluorescence spectrum at an excitation wavelength of 580 nm. DETAILED DESCRIPTION

[0026] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0027] Comparative Example 1

[0028] 0.096 g of phycocyanin was weighed and dissolved in 160 mL of pure water, protected from light, and magnetically stirred at 600 rpm for 30 min to obtain an untreated phycocyanin solution PC-W.

[0029] Comparative Example 2

[0030] Step 1: Weigh 0.096 g of phycocyanin and dissolve it in 120 mL of water, protect from light, and stir magnetically at 600 rpm for 30 min to obtain a phycocyanin solution.

[0031] Step 2: Inject 40 mL of 70% ethanol into the phycocyanin solution in step 1, protect from light, and stir magnetically at 600 rpm for 30 min.

[0032] Step 3: The solution obtained in step 2 is subjected to rotary evaporation at 40°C to remove ethanol, and the same volume of water is added to obtain a rotary evaporated phycocyanin solution PC.

[0033] Example 1

[0034] Step 1: Weigh 0.096 g of phycocyanin and dissolve it in 120 mL of water, protect from light, and stir magnetically at 600 rpm for 30 min to obtain a phycocyanin solution.

[0035] Step 2: Weigh 0.032 g of zein and dissolve it in 40 mL of 70% ethanol, and stir it with a magnetic stirrer at 600 rpm overnight to obtain a zein solution.

[0036] Step 3: Inject the zein solution in step 2 into the phycocyanin solution in step 1 with a syringe, protect from light, and stir magnetically at 600 rpm for 30 min.

[0037] Step 4: Remove ethanol from the solution obtained in step 3 by rotary evaporation at 40° C., and add the same volume of water to obtain a phycocyanin-zein complex (PC-Zein-3:1) with a mass ratio of 3:1.

[0038] Example 2

[0039] The difference between Example 2 and Example 1 is that in step 2, 0.048 g of zein is weighed and dissolved in 40 mL of 70% ethanol, and finally in step 4, a phycocyanin-zein complex (PC-Zein-2:1) with a mass ratio of 2:1 is obtained.

[0040] Example 3

[0041] The difference between Example 3 and Example 1 is that in step 2, 0.096 g of zein is weighed and dissolved in 40 mL of 70% ethanol, and finally in step 4, a phycocyanin-zein complex (PC-Zein-1:1) with a mass ratio of 1:1 is obtained.

[0042] Example 4

[0043] The difference between Example 4 and Example 1 is that in step 2, 0.192 g of zein is weighed and dissolved in 40 mL of 70% ethanol, and finally in step 4, a phycocyanin-zein complex (PC-Zein-1:2) with a mass ratio of 1:2 is obtained.

[0044] Example 5

[0045] The difference between Example 5 and Example 1 is that in step 2, 0.288 g of zein is weighed and dissolved in 40 mL of 70% ethanol, and finally in step 4, a phycocyanin-zein complex (PC-Zein-1:3) with a mass ratio of 1:3 is obtained.

[0046] Characterization of Phycocyanin-Zein Complex

[0047] 1. Particle size and potential determination of phycocyanin-zein complex

[0048] The zeta potential and particle size of the phycocyanin-zein complex were measured using a nanoparticle size analyzer. The particle size measurement was performed after Comparative Example 1, Comparative Example 2, and Example 1 were diluted 10 times with pure water. The measurement parameters were set as follows: protein was the particle material, with a refractive index of 1.450; water was the dispersant, with a refractive index of 1.330; and the temperature was 25°C.

[0049] The results are shown in Table 1.

[0050] Table 1 Potential and particle size of phycocyanin-zein complex

[0051]

[0052]

[0053] Note: The values ​​are mean ± standard deviation. Different superscript letters in the same column indicate statistically significant differences (p<0.05).

[0054] As shown in Table 1, the zeta potentials of Comparative Example 1, Comparative Example 2 and Examples 1-5 are all around -20mV, and the difference is not significant, which indicates that electrostatic interaction is not the main mode of interaction between phycocyanin and zein. Since the light absorption of the chromophore in phycocyanin can affect the particle size analysis by dynamic light scattering, the complex formed when the addition amount of zein is less than that of phycocyanin is not suitable for the analysis of particle size. When the addition amount of zein is greater than that of phycocyanin, the size of the phycocyanin-zein complex increases from 122nm to 328nm, indicating that the interaction between phycocyanin and zein makes the aggregate formed larger, resulting in an increase in particle size. At the same time, the aggregate formed by the interaction of phycocyanin and zein effectively covers the chromophore of phycocyanin, thereby detecting the size of the aggregate particles, which indicates that the phycocyanin-zein complex is the existence form of zein encapsulating phycocyanin.

[0055] 2. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis of phycocyanin-zein complex

[0056] Mix the phycocyanin-zein complex with 5× protein loading buffer at a volume ratio of 4:1, heat in boiling water for 7 minutes, and then cool to room temperature. Add 20 μL of sample to each well of the precast gel with a separation gel mass concentration of 15%. After electrophoresis at 80V for 30 minutes, adjust the voltage to 120V and continue electrophoresis until the blue band migrates to 0.5-1 cm from the bottom of the gel, then stop electrophoresis. Subsequently, place the gel in Coomassie Brilliant Blue solution for staining. After staining at room temperature for 4 hours, place the gel in a destaining solution for decolorization until the band is visualized.

[0057] The sodium dodecyl sulfate-polyacrylamide gel electrophoresis of phycocyanin-zein complex is shown in Figure 1As shown. Due to the action of sodium dodecyl sulfate, the α-subunit and β-subunit of phycocyanin are separated, showing two similar bands with molecular weights of 18 to 20 kDa. Two clear bands with molecular weights of 21 to 25 kDa appear above the phycocyanin, which are the main bands of zein. As the content of zein increases, the bands become more and more obvious and enhanced. A blue tail appears above the band of zein in Examples 1-5, indicating that cross-linking may have occurred between protein molecules or a robust coupling that cannot be separated by sodium dodecyl sulfate has been formed. The dark blue tails of Examples 4 and 5 are significantly enhanced and the molecular weight increases, indicating that the interaction between phycocyanin and zein molecules is stronger and the number of bindings has also increased.

[0058] 3. Initial fluorescence spectrum of phycocyanin-zein complex

[0059] Fluorescence spectra of the original samples were measured using a fluorescence spectrophotometer. The excitation wavelengths were set to 280 nm and 580 nm, respectively, and two emission spectra were obtained in the wavelength range of 300-450 nm and 600-750 nm, respectively. The slit width was set to 10 nm. All samples were diluted 5 times before measurement.

[0060] The initial fluorescence spectra of Comparative Example 1, Comparative Example 2 and Examples 1-5 are as follows: Figure 2As shown. Tryptophan residues are one of the few amino acids with fluorescent properties in proteins. The intrinsic fluorescence spectrum of proteins produced when excited at 280nm can be used to characterize changes in the tertiary structure of proteins. The unfolding of the protein structure may expose tryptophan to the solvent, resulting in a red shift in intrinsic fluorescence. On the contrary, protein aggregation and precipitation will bury tryptophan in the hydrophobic core, resulting in a blue shift in intrinsic fluorescence, and may be accompanied by a decrease in fluorescence intensity. The peak position of the fluorescence spectrum of Comparative Example 2 (321nm) is blue-shifted compared to Comparative Example 1 (331nm), indicating that adding ethanol to phycocyanin and then rotary evaporation to remove ethanol will cause phycocyanin aggregation. With the increase of the mass ratio of zein, the peak position of the fluorescence spectrum of phycocyanin-zein complex blue-shifts from 312nm to 307nm, indicating that the interaction between phycocyanin and zein causes protein aggregation to form particles of a certain size. PC-Zein-1:1 of Comparative Example 3 has become the turning point of the fluorescence intensity of the phycocyanin-zein complex under 280nm excitation, showing a trend of first rising and then falling. When the zein content is higher than that of phycocyanin, the fluorescence intensity begins to decrease. This is because the excessive concentration of zein increases the aggregation of the phycocyanin-zein complex, resulting in the internal tryptophan being covered. When the excitation wavelength is 580nm, Comparative Example 1 shows a strong emission peak near 650nm. The fluorescence spectra of Comparative Example 2 and Examples 1-5 all show a blue shift, indicating that the microenvironment hydrophobicity of phycocyanin is stronger. At the same time, the fluorescence intensity of all examples has decreased, especially PC-Zein-1:2 of Example 4 and PC-Zein-1:3 of Example 5, but the fluorescence of the examples has not disappeared, which shows that the addition of zein retains the characteristic structure of phycocyanin but changes the local structural changes of the protein near the chromophore.

[0061] 4. Fourier transform infrared spectroscopy determination of phycocyanin-zein complex

[0062] All the original samples of the comparative examples and embodiments were freeze-dried to obtain powders. The samples were mixed with dried potassium bromide at a ratio of 1:100 (m / m), and pure KBr was used as the scanning background. The number of test scans was 64, and the wave number was 400-4000 cm -1 .

[0063] The Fourier transform infrared spectra of phycocyanin and zein are shown in Figure 3 The 3303 and 3304 cm-1 values ​​of zein and Comparative Example 1 in the amide A region are shown in Table 1. -1There is a distinct broad peak, which is attributed to NH stretching and OH bending. After the phycocyanin and zein are compounded, the peaks of Comparative Examples 1-5 in this region move slightly, indicating that there is a hydrogen bond interaction between phycocyanin and zein. The region closely related to the protein structure in the infrared spectrum is the amide I band (1600-1720 cm -1 ) and amide II band (1475-1575 cm -1 ), representing the stretching vibration of the C=O double bond and the bending vibration of the NH bond, respectively. The amide I band contains rich information about the secondary structure of proteins, such as 1645-1662 cm -1 、1613~1637cm -1 Corresponding to α-helix and β-sheet structure respectively. -1 There is an obvious peak at 1613-1637 cm, indicating the α-helical structure of phycocyanin, and the peak of the embodiment has hardly moved compared with the comparative example 1, which shows that the α-helical structure of phycocyanin is retained after the addition of zein. During the self-assembly process, zein may undergo a transition from α-helix to β-fold in a hydrophilic environment. However, the peak of the embodiment at 1613-1637 cm -1 No obvious peak appeared in the zein, indicating that the interaction between zein and phycocyanin prevented the formation of the β-folding structure of zein and retained the main α-helical structure of phycocyanin, so that the phycocyanin-zein complex showed excellent stability in the subsequent light storage experiment.

[0064] 5. Scanning electron microscopy determination of phycocyanin-zein complex

[0065] All comparative examples and examples were freeze-dried to obtain powders. The sample surface was sprayed with gold and then tested using a scanning electron microscope at an accelerating voltage of 3.0 KV.

[0066] SEM images of phycocyanin-zein complex Figure 4As shown. Comparative Example 1 shows a large spherical structure with a smooth surface. Comparative Example 2 shows a small spherical structure with a fuzzy outline, which may be due to the addition of ethanol causing changes in the surrounding environment of phycocyanin during the preparation process, resulting in its own aggregation and precipitation. The particles of the embodiment present a uniform sphere, and as the content of zein increases, the particle size gradually increases, which is related to the inherent characteristics of zein, and in the anti-solvent precipitation process, zein is easy to self-assemble into particles. These results show that there is an interaction between phycocyanin and zein molecules, resulting in the formation of a spherical structure by molecular aggregation, and zein forms a certain encapsulation of phycocyanin, which also explains the initial fluorescence spectrum peak obtained by exciting the phycocyanin-zein complex at 580nm from PC-Zein-1:1 and the initial fluorescence intensity of PC-Zein-1:3 is the lowest.

[0067] Determination of the light storage stability of phycocyanin-zein complex

[0068] 1. Visual color and color difference changes of phycocyanin-zein complex before and after storage

[0069] The colorimetric analysis of all comparative examples and embodiments was performed using a colorimeter. The samples were placed in a 12-well cell culture plate and placed on white paper, and the measurement was performed under the condition of keeping the indoor light source consistent. The L, a, and b values ​​of the samples were recorded, and the ΔE value of the samples was calculated by the following formula. At the same time, photos were taken to reflect the changes in the visual appearance of the samples.

[0070] ΔE=√(LL 0 ) 2 +(aa 0 ) 2 +(bb 0 ) 2 , where L 0 、a 0 、b 0 L, a, and b values ​​at day 0 for all comparative examples and embodiments.

[0071] Visual changes of phycocyanin-zein complex before and after storage Figure 5 The initial color difference between the example and the comparative example is not obvious. After 28 days of light storage, the example 5 maintains a good blue color. In order to intuitively study the color change of phycocyanin, the CIELab color space is used to provide clear color information. The results are shown in Figure 5As shown in the small figure b. Among them, the L value defines the brightness change from black (0) to white (100), the a value defines the brightness change from green (-) to red (+), and the b value defines the brightness change from blue (-) to yellow (+). After adding zein to phycocyanin, the L value did not change significantly, while the a value decreased with the increase of zein content. This decrease may be due to the yellow of zein mixed with the blue of phycocyanin, resulting in a greenish hue, causing the a value to shift to a negative value. With the increase of zein content, the b value of the phycocyanin-zein complex increased from -13.7 to -8.6, which is related to the yellow color of zein. And from the characterization results, the encapsulation of phycocyanin by zein also led to a decrease in the absolute value of the b value of the phycocyanin-zein complex, that is, the blue color was weakened.

[0072] After 28 days of continuous illumination at 25°C, the L values ​​of all samples increased, indicating that the samples became brighter overall. From the perspective of visual color change and b-value, in the second week of illumination, Comparative Examples 1, 2 and Examples 1, 2 began to lose their blue color significantly. By the third week, Example 3 also lost most of its blue color, while Example 5 remained bright blue during the 28-day storage period, with a b-value of -7.4 on the 28th day. In addition, the ΔE of Example 5 was 1.3, which was the smallest change compared to the other samples, which was conducive to maintaining the stable quality of the product. It can be seen that a higher amount of zein added makes phycocyanin more resistant to denaturation caused by light exposure.

[0073] 2. Fluorescence spectrum of phycocyanin-zein complex after 28 days of light storage

[0074] Fluorescence spectra of the original samples were measured using a fluorescence spectrophotometer. The excitation wavelengths were set to 280 nm and 580 nm, respectively, and two emission spectra were obtained in the wavelength range of 300-450 nm and 600-750 nm, respectively. The slit width was set to 10 nm. All samples were diluted 5 times before measurement.

[0075] The fluorescence spectrum of the phycocyanin-zein complex after 28 days of light storage is as follows Figure 6 As shown. Figure 6 As shown in the middle panel a, the peak intensity of the intrinsic fluorescence spectra of all samples increased significantly, indicating that after 28 days of storage, the tryptophan content exposed to the solution increased. The fluorescence spectra of Examples 1 and 2 showed a significant red shift, indicating that the extension of the protein structure increased, exposing the tryptophan originally hidden inside the protein. The tryptophan content of Examples 3, 4 and 5 increased, but the fluorescence spectra did not undergo a significant red shift, indicating that the protein structure remained tight, and the increase in tryptophan enhanced the hydrophobic interaction of the protein, which helped maintain the stability of the protein.

[0076] The fluorescence yield of phycocyanin itself is related to the conformational freedom of the pyrrole ring of the chromophore. If the chromophore is exposed to the solvent or the dissociation of phycocyanin increases its conformational freedom, the phycocyanin will lose its fluorescence properties to varying degrees. Figure 6 Panel b in the middle is the fluorescence emission spectrum excited at 580nm. After 28 days of illumination, the comparative example and Examples 1, 2 and 3 almost lost fluorescence. Combined with the intrinsic fluorescence spectrum, this phenomenon may be attributed to the unfolding of the protein structure, resulting in increased exposure of the chromophore and loss of fluorescence properties due to lack of protection of the pyrrole structure. Although the fluorescence intensity of Examples 4 and 5 also decreased, it still maintained a higher fluorescence intensity compared with the comparative example and other examples, especially Example 5. The above results show that the phycocyanin-zein complex can maintain the stability of the chromophore structure through hydrophobic interactions.

[0077] It should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof 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.

[0078] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A composite for improving the light storage stability of phycocyanin, characterized in that: The complex is a phycocyanin-zein complex composed of two proteins, phycocyanin and zein.

2. The composite for improving the light storage stability of phycocyanin according to claim 1, characterized in that: The phycocyanin-zein complex is spherical.

3. The composite for improving the light storage stability of phycocyanin according to claim 1, characterized in that: The complex was grown in a light incubator with the temperature set at 25°C and 24h of continuous light.

4. The method for preparing the composite for improving the light storage stability of phycocyanin according to claim 1, characterized in that: The complex is prepared by an anti-solvent precipitation method, comprising the following steps: Step 1: Dissolve phycocyanin in pure water, stir for 30 minutes in the dark, and obtain a phycocyanin solution with a concentration of 0.8 mg / mL; Step 2: dissolving zein in 70% ethanol and stirring overnight to obtain a zein solution with a concentration range of 0.8 mg / mL to 7.2 mg / mL; Step 3: Add the zein solution to the phycocyanin solution using a syringe, stir for 30 minutes in a dark environment, and obtain a mixed solution with a mass ratio of phycocyanin to zein of 3:1 to 1:3; Step 4: Remove ethanol from the mixed solution of phycocyanin and zein by rotary evaporation, and add an equal volume of pure water to obtain a phycocyanin-zein complex (PC-Zein).

5. The method for preparing a composite for improving the light storage stability of phycocyanin according to claim 4, characterized in that: The phycocyanin solution in step 1 has a purity greater than 0.

7.

6. The method for preparing a composite for improving the light storage stability of phycocyanin according to claim 4, characterized in that: The volume ratio of the phycocyanin solution to the zein solution in step 1 and step 2 is 3:

1.

7. The method for preparing a composite for improving the light storage stability of phycocyanin according to claim 4, characterized in that: The stirring in step 1, step 2 and step 3 is magnetic stirring with a rotation speed of 600 rpm.

8. The method for preparing a composite for improving the light storage stability of phycocyanin according to claim 4, characterized in that: The rotary evaporation temperature in step 4 is 40°C.

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