A micellar system for improving the color stability of phycocyanin and a preparation method thereof

Abstract

The application belongs to the technical field of food processing, and particularly relates to a method for improving color stability of phycocyanin by using a micellar system. The application provides a method for improving color stability of phycyanin by using a micellar system, so that the phycocyanin can maintain its blue color in a pasteurization process. The preparation method of the application is easy to apply, does not require complex or expensive equipment, is high in safety, and has a small additive amount and does not affect the original sensory properties of food. Not only the defect that the phycocyanin is easy to change and fade in color when heated in the production and processing process is solved, but also the technical problems of low action efficiency, low safety and difficulty in large-scale production in improving the thermal stability of phycocyanin are solved.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of food processing, and particularly relates to a micellar system for improving the color stability of phycocyanin and a preparation method thereof. BACKGROUND

[0002] Phycocyanin is a rare edible blue pigment in nature, which has high color and purity and does not produce bad smell or taste. At the same time, phycocyanin has bright color and high transparency, and can well improve the appearance of food and beverage and increase the aesthetic degree and attraction. In 2013 / 2014, the U.S. FDA granted permission for the use of phycocyanin in some foods, including beverages, cheese, ice cream, candy, chewing gum, yogurt, pudding and many other common foods. Phycocyanin is one of the natural blue pigments approved for use in food in China's GB2760-2014 Food Additive Standard, which can not only impart novel blue color to food, but also has physiological activities such as antioxidant, anti-inflammatory, anti-tumor and immune regulation, and can play a certain health function. However, phycocyanin has poor thermal stability, and even under pasteurization conditions, it cannot be tolerated, so the application of phycocyanin is greatly limited, and it is now mainly used in cold drinks or cold processed foods that do not involve heat processing. The blue color of phycocyanin gradually fades above 50℃. As an essential step in food processing, heat sterilization greatly and inevitably destroys the color stability of phycocyanin. Therefore, improving the thermal stability of phycocyanin has practical significance for its practical application.

[0003] Adding a stabilizer is the simplest method to improve the stability of phycocyanin. This method is easy to apply and does not require complex or expensive equipment, but requires that the stabilizer be safe, non-toxic and harmless, and that the additive amount be large. At present, the commonly used stabilizers mainly include some small molecules such as glucose, sucrose, fructose, sorbitol and glycerol, and 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%, and the high addition amount will cause the viscosity to increase, so it is only suitable for coloring agents for hard candies and other food substrates, and is not suitable for liquid beverages. In addition to using sugar as a stabilizer, some studies have used sodium dodecyl sulfate to stabilize the blue color of phycocyanin. Sodium dodecyl sulfate stabilizes the dominant helical structure in phycocyanin, thereby stabilizing the blue color of phycocyanin and preventing it from turning green at low pH. However, sodium dodecyl sulfate is not included in the food additive standard, and cannot be applied to the food industry.

[0004] Therefore, it is of great significance to study a stable phycocyanin that can be widely applied in the food industry. SUMMARY

[0005] The present application aims to provide a micellar system for improving the color stability of phycocyanin and a preparation method thereof to make up for the deficiency of the prior art.

[0006] To achieve the above-mentioned purpose, the present application is implemented by the following technical solutions:

[0007] A micellar system for improving the color stability of phycocyanin, which is a stable micellar structure formed by dissolving a surfactant in water; the polar end of the surfactant faces outward, and the non-polar end faces inward; the micellar system is mixed with phycocyanin to obtain a phycocyanin-micellar system.

[0008] The preparation method of the micellar system is to dissolve the surfactant in deionized water, and then obtain the micellar system by low-temperature stirring treatment; then, the phycocyanin solution is mixed with the micellar system, and the mixture obtained by low-temperature, light-avoiding and gentle stirring is the phycocyanin-micellar system.

[0009] Further, the surfactant is one of Tween, Span, casein or denatured starch.

[0010] Further, the denatured starch is octenyl succinate starch; the octenyl succinate starch is obtained by esterification of starch with octenyl succinic anhydride, and the octenyl succinate starch chain simultaneously introduces hydrophilic carboxyl and hydrophobic alkenyl long chain, so that the octenyl succinate starch has hydrophilic and hydrophobic properties, thereby making the emulsion system formed by emulsification have high stability.

[0011] Further, the micellar system can be formed by self-assembly, and the denatured starch micellar system has a more prominent effect on improving the color stability of phycocyanin. 4.5 mg / mL is the critical micellar concentration of octenyl succinate starch, and the selected concentration range can construct the micellar system without causing excessive viscosity and affecting the original sensory properties of the food.

[0012] Further, the concentration of the octenyl succinate starch in the micellar system is 4.5 mg / mL to 22.5 mg / mL. Within this range, the color stability of phycocyanin is significantly improved, the color difference is smaller compared with the phycocyanin without heating, and the pigment retention rate is improved. The surface hydrophobicity of the micellar system is reduced, indicating that the chromophore may be wrapped inside by the octenyl succinate starch and stabilized by hydrophobic interaction. The net charge of the micellar system is increased, indicating that the stability of this state is improved, because higher surface charge can provide stronger electrostatic repulsion between particles to overcome the aggregation between proteins. The phycocyanin in the micellar system is distributed loosely, the interaction between proteins is reduced, and a linear micellar system is obviously formed, which has good stability.

[0013] Further, the phycocyanin solution has a purity of not less than 0.7, meeting the purity requirement of food-grade phycocyanin.

[0014] Further, the temperature of the low-temperature stirring is 4-10 DEG C. Temperature increase can cause the extension reaction of phycobilin-phycobilin structure, so that the conformation of phycobilin is changed from linear to circular, thereby affecting the three-dimensional structure of phycocyanin. Therefore, all samples should be treated under low-temperature conditions.

[0015] Further, the time of the low-temperature stirring is 2-6 h. The stirring and dissolving time of octenyl succinate starch should be long enough to make the whole system uniform.

[0016] Further, the time of the low-temperature, light-avoiding and gentle stirring is 5-30 min. Phycocyanin is a water-soluble protein, and can be used to construct a micellar system by using a direct stirring and dissolving method. With the help of appropriate temperature and stirring, the micellar system can be gradually self-assembled to form micelles, and the micelles obtained by the method have good dispersity.

[0017] Phycocyanin is obtained from microalgae such as Spirulina platensis, and is obtained by repeated freezing and thawing, ammonium sulfate precipitation, redissolving, dialysis and the like.

[0018] The present application has the following advantages and beneficial effects:

[0019] The product prepared by the present application has a blue color unique to phycocyanin, and after pasteurization, the color retention rate of the solution is significantly improved compared with that of pure phycocyanin. The present application retains the advantages of strong coloring power and strong functional activity of phycocyanin, and the raw materials used are non-toxic and non-hazardous reagents, which are 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 application not only solves the defect that phycocyanin is easily faded by heat in the production and processing process, but also solves the technical problems of low efficiency, low safety and difficulty in large-scale production in improving the thermal stability of phycocyanin.

[0020] The present application can improve the color stability of phycocyanin, so that the blue color of phycocyanin can be maintained during pasteurization. The method is simple and easy to apply, has high safety, small additive amount and does not affect the original sensory properties of food, and can be applied to various food substrates, thereby expanding the application range of phycocyanin in the food industry. BRIEF DESCRIPTION OF DRAWINGS

[0021] Figure 1 Comparison of color difference of phycocyanin-micellar system before and after pasteurization.

[0022] Figure 2 Comparison of color retention rate of phycocyanin-micellar system before and after pasteurization.

[0023] Figure 3 Comparison of phycocyanin-micellar system chromophore conformation before and after pasteurization.

[0024] Figure 4 Comparison of phycocyanin-micellar system molecular weight before and after pasteurization.

[0025] Figure 5 Comparison of phycocyanin-micellar system net charge before and after pasteurization.

[0026] Figure 6 Comparison of phycocyanin-micellar system surface hydrophobicity before and after pasteurization.

[0027] Figure 7 Comparison of phycocyanin-micellar system microstructure before and after pasteurization. DETAILED DESCRIPTION

[0028] In order to make the objects, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application are described clearly and completely below. Obviously, the described embodiments are some of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work fall within the protection scope of the present application.

[0029] Unless otherwise specified, the materials and reagents used in the following examples are commercially available.

[0030] Comparative Example 1:

[0031] 1. Raw material: phycocyanin solution 100 parts, stored at 4°C in the dark.

[0032] 2. Detect the color, pigment retention rate, chromophore conformation, molecular weight, net charge, surface hydrophobicity and microstructure changes of the sample.

[0033] The visible-ultraviolet light absorption ratio (AVIS / AUV) can represent the conformation of the tetrapyrrole chromophore. Generally, in the extended conformation, AVIS / AUV >> 1, while in the cyclic conformation, AVIS / AUV < 1, as shown in Figure 3 Avis / Auv >> 1, indicating that the phycocyanin chromophore maintains its extended geometry in the natural state. As shown in Figure 4 The degree of protein aggregation in Comparative Example 1 is high, and the molecular weight is mainly concentrated around 140 kDa. As shown in Figure 5 The net charge of Comparative Example 1 is the highest, indicating that this state has the highest stability, because higher surface charge can provide stronger electrostatic repulsion between particles to overcome the aggregation between proteins. As shown in Figure 6As shown in Table 1, the surface hydrophobicity of the comparative example 1 is the lowest, which indicates that in the natural state, most of the hydrophobic amino acid residues of the phycocyanin are in the interior of the molecule, forming a hydrophobic core, thereby maintaining the natural structure of the phycocyanin. As shown in Table 1, Figure 7 As shown in Table 1, the phycocyanin in the comparative example 1 is distributed loosely, and the interaction between the proteins is small, and this state has good stability.

[0034] Comparative example 2

[0035] 1. Raw material: 100 parts of phycocyanin solution.

[0036] 2. Pasteurization: the phycocyanin solution was placed in a 65°C water bath for 30 minutes, and then immediately cooled.

[0037] 3. The color, pigment retention rate, chromophore conformation, molecular weight, net charge, surface hydrophobicity and microstructure changes of the sample after pasteurization were detected.

[0038] ΔL*a*b* represents the color change compared with the comparative example 1. As shown in Table 1, Figure 1 After pasteurization, ΔL* in the comparative example 2 is negative, indicating that the color becomes darker; Δa* in the comparative example 2 is negative, indicating that the color becomes green; Δb* in the comparative example 2 is positive, indicating that the blue color decreases. The ΔE value is the largest, indicating that the color difference of the comparative example 2 is the largest compared with the comparative example 1. As shown in Table 1, Figure 3 The AVIS / AUV in the comparative example 2 is significantly reduced, indicating that the chromophore conformation changes, i.e. rearrangement caused by protein structure denaturation. As shown in Table 1, Figure 4 The aggregation state of the phycocyanin in the comparative example 2 changes, and high molecular aggregates appear, and the number of protein bands below 66 kDa increases significantly. As shown in Table 1, Figure 5 The net charge of the phycocyanin in the comparative example 2 is the lowest, indicating that this state has the lowest stability, because higher surface charge can provide stronger electrostatic repulsion between particles to overcome the aggregation between proteins. As shown in Table 1, Figure 6 The surface hydrophobicity of the comparative example 2 significantly increases, indicating that the hydrophobic amino acid residues of the phycocyanin are exposed, and the structure of the phycocyanin is destroyed. As shown in Table 1, Figure 7 The phycocyanin in the comparative example 2 is distributed tightly, the particle size increases, the interaction between the proteins increases, and the proteins aggregate, and this state has poor stability.

[0039] Example 1

[0040] 1. Raw material: 100 parts of phycocyanin solution, 100 parts of 9 mg / mL octenyl succinate starch.

[0041] 2. Preparation of phycocyanin micellar system: The octenyl succinate starch was dissolved in deionized water, and the system 1 was obtained by low-temperature stirring treatment. The phycocyanin solution was mixed with the system 1 at a ratio of 1:1 (w / w), and then the phycocyanin micellar system was obtained by low-temperature, light-protected and gentle stirring.

[0042] 3. Pasteurization: The micellar system was placed in a 65°C water bath for 30 min, and then immediately cooled.

[0043] 4. The color, pigment retention rate, chromophore conformation, molecular weight, net charge, surface hydrophobicity and microstructure changes of the sample after pasteurization were detected.

[0044] ΔL*a*b* represents the color change compared with Comparative Example 1. As shown in Table 1, after pasteurization, the color brightness of Example 1 increased, the green color decreased, the blue color increased, and the color difference was the smallest. Figure 1 As shown in Table 2, the AVIS / AUV and surface hydrophobicity of Example 1 were significantly lower than those of Comparative Example 2, indicating that the chromophore group may be wrapped inside by the octenyl succinate starch and stabilized by hydrophobic interaction. Figure 3 As shown in Table 3, the aggregation state of the phycocyanin in Example 1 changed, and the number of protein bands near 140 kDa increased significantly. 6 As shown in Table 4, the net charge of the phycocyanin in Example 1 was significantly higher than that in Comparative Example 2, indicating that the state stability was improved, because higher surface charge can provide stronger electrostatic repulsion between particles to overcome the aggregation between proteins. Figure 4 As shown in Table 5, the phycocyanin in Example 1 was distributed loosely, the protein-protein interaction was reduced, and a linear micellar system was formed obviously, and the state stability was good. Figure 5 Figure 7 Example 2

[0045] 1. Raw materials: 100 parts of phycocyanin solution, 22.5 mg / mL of octenyl succinate starch 100 parts.

[0046] 2. Preparation of phycocyanin micellar system: The octenyl succinate starch was dissolved in deionized water, and the system 1 was obtained by low-temperature stirring treatment. The phycocyanin solution was mixed with the system 1 at a ratio of 1:1 (w / w), and then the phycocyanin micellar system was obtained by low-temperature, light-protected and gentle stirring.

[0047] 3. Pasteurization: The micellar system was placed in a 65°C water bath for 30 min, and then immediately cooled.

[0048] 4. The color, pigment retention rate, chromophore conformation, molecular weight, net charge, surface hydrophobicity and microstructure changes of the sample after pasteurization were detected.

[0049]

[0050] ​​ΔL*a*b* represents the chromaticity change compared with Comparative Example 1. Figure 1 As shown, after pasteurization, the color brightness of Example 2 is improved, the green becomes less, the blue increases, and the color difference becomes smaller. Figure 2 As shown in Figure 2, after pasteurization, the pigment retention rate of Example 2 is significantly improved, indicating that Example 2 can improve the color stability of phycocyanin. Figure 3 、 6 As shown in Figure 2, the surface hydrophobicity of AVIS / AUV in Example 2 is significantly lower than that in Comparative Example 2, indicating that the chromophore may be wrapped inside by octenyl succinate starch and stabilized by hydrophobic interactions. Figure 4 As shown in Figure 2, the aggregation state of phycocyanin in Example 2 changed, and the protein bands concentrated near 140 kDa became significantly more numerous. Figure 5 The net charge of phycocyanin in Example 2 is significantly higher than that in Comparative Example 2, indicating that the stability of the state is improved, because the higher surface charge can provide stronger electrostatic repulsion between particles to overcome the aggregation between proteins. Figure 7 As shown, the phycocyanin in Example 2 is loosely distributed, the protein-protein interaction is reduced, and a linear micelle system is obviously formed, and this state has good stability.

[0051] Example 3

[0052] 1. Raw materials: 100 parts of phycocyanin solution, 100 parts of 45 mg / mL octenylsuccinate starch.

[0053] 2. Preparation of phycocyanin micelle system: Octenyl succinate-esterified starch was dissolved in deionized water and stirred at low temperature to obtain system 1. The phycocyanin solution and system 1 were mixed at a ratio of 1:1 (w / w) and stirred gently at low temperature in the dark to obtain the phycocyanin micelle system.

[0054] 3. Pasteurization: Place the micellar system in a 65°C water bath for 30 minutes and then cool immediately.

[0055] 4. Detect changes in color, pigment retention, chromophore conformation, molecular weight, net charge, surface hydrophobicity, and microstructure of samples after pasteurization.

[0056] ΔL*a*b* represents the chromaticity change compared with Comparative Example 1. Figure 1 As shown, after pasteurization, the color brightness of Example 3 is improved, the green becomes less, the blue increases, and the color difference becomes smaller. Figure 2 As shown in Figure 3, after pasteurization, the pigment retention rate of Example 3 is significantly improved, indicating that Example 3 can improve the color stability of phycocyanin. Figure 3 、 6As shown, the surface hydrophobicity of the phycocyanin of Example 3 is significantly lower than that of Comparative Example 2, indicating that the chromophore of phycocyanin can be wrapped inside by octenyl succinate starch and stabilized by hydrophobic interaction. Figure 4 As shown, the aggregation state of the phycocyanin of Example 3 is changed, and the number of protein bands near 140 kDa is obviously increased. As shown, Figure 5 As shown, the net charge of the phycocyanin of Example 3 is significantly higher than that of Comparative Example 2, indicating that the state stability is improved, because higher surface charge can provide stronger electrostatic repulsion between particles to overcome the aggregation between proteins. As shown, Figure 7 As shown, the phycocyanin of Example 3 is distributed loosely, the interaction between proteins is reduced, and a linear micellar system is obviously formed, and the state stability is good.

[0057] The micellar system provided by the present application for improving the color stability of phycocyanin is easy to apply, does not require complex or expensive equipment, has high safety, and has small additive amount without affecting the original sensory properties of food. After pasteurization, it has smaller color difference, higher pigment retention rate, and the chromophore of phycocyanin is closer to the natural conformation, which can significantly improve the color stability of phycocyanin.

[0058] The specific embodiments of the present application are described above. It should be understood that the present application is not limited to the specific embodiments described above, and various modifications or changes can be made by those skilled in the art within the scope of the claims, which does not affect the essential content of the present application.

Claims

1. A micellar system for improving the coloration stability of phycocyanin, characterized by, The micellar system is formed by dissolving octenyl succinate starch in water to form a stable micellar structure; the polar end of the octenyl succinate starch faces outward, and the non-polar end faces inward; the micellar system is mixed with phycocyanin to obtain a phycocyanin-micellar system; the concentration of the octenyl succinate starch is 4.5 mg / mL to 22.5 mg / mL; and the phycocyanin solution is mixed with the octenyl succinate starch micelles at a mass ratio of 1:

1.

2. A method for preparing a micellar system for improving the coloration stability of phycocyanin, characterized by, The octenyl succinate starch is dissolved in deionized water, and low-temperature stirring treatment is performed to obtain a micellar system; then the phycocyanin solution is mixed with the micellar system, and low-temperature, light-avoiding, and gentle stirring are performed to obtain a mixture, which is a phycocyanin-micellar system; the concentration of the octenyl succinate starch is 4.5 mg / mL to 22.5 mg / mL; and the phycocyanin solution is mixed with the octenyl succinate starch micelles at a mass ratio of 1:

1.

3. The production method according to claim 2, wherein The purity of the phycocyanin solution is not less than 0.7, meeting the purity requirement of food-grade phycocyanin.

4. The production method according to claim 2, wherein The temperature of the low-temperature stirring is 4 to 10℃.

5. The production method according to claim 2, wherein The time of the low-temperature stirring is 2 to 6 h.

6. The preparation method according to claim 2, wherein After the phycocyanin solution is mixed with the micellar system, the time of the low-temperature, light-avoiding, and gentle stirring is 5 to 30 min.

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