Method for improving performance of blueberry anthocyanin by using tamarind polysaccharide

Abstract

The invention belongs to the technical field of natural pigments, and particularly relates to a method for improving the performance of blueberry anthocyanin by using tamarind polysaccharide. According to the method for improving the performance of the blueberry anthocyanin by utilizing the tamarind polysaccharide, after a tamarind polysaccharide solution and a blueberry anthocyanin solution are prepared, the tamarind polysaccharide which is not subjected to enzymolysis or the tamarind polysaccharide which is subjected to enzyme treatment such as beta-galactosidase and the like is added into the blueberry anthocyanin solution for mixing; a blueberry anthocyanin stable solution is obtained; blueberry anthocyanin and tamarind polysaccharide in the blueberry anthocyanin stabilizing solution are compounded through non-covalent bonds such as hydrogen bonds, so that the stability of the blueberry anthocyanin in light, heat and digestive systems is improved, the oxidation resistance is enhanced, and the color is improved; therefore, the technical problem that the performance of the blueberry anthocyanin is easily reduced at present is solved.

Description

Technical Field

[0001] This application belongs to the field of natural pigment technology, and in particular relates to a method for improving the anthocyanin properties of blueberries using tamarind polysaccharides. Background Technology

[0002] Blueberry anthocyanins, extracted from blueberries, are natural compounds rich in delphinidin and other anthocyanins. They are not only a safe natural pigment, but anthocyanins also have certain effects such as improving eyesight, lowering blood lipids, and anti-oxidation. Extracting blueberry anthocyanins from blueberries aligns with the current development trend of food colorings towards "natural, healthy, and multifunctional" products.

[0003] However, there are very few products containing blueberry anthocyanins at present, mainly because blueberry anthocyanins are unstable and easily degraded, which reduces their performance. Therefore, it is necessary to develop a process to improve the stability of blueberry anthocyanins and enhance their performance. Summary of the Invention

[0004] In view of this, this application provides a method for improving the performance of blueberry anthocyanins using tamarind polysaccharides, in order to solve the current technical problem that the performance of blueberry anthocyanins is prone to decline.

[0005] The first aspect of this application provides a method for enhancing the anthocyanin properties of blueberries using tamarind polysaccharides, comprising the following steps: The steps for preparing tamarind polysaccharide solution are as follows: dissolve tamarind polysaccharide in water to obtain tamarind polysaccharide solution, or dissolve tamarind polysaccharide in water and perform enzymatic hydrolysis to obtain enzymatically hydrolyzed tamarind polysaccharide solution; The steps for preparing blueberry anthocyanin solution are as follows: Dissolve blueberry anthocyanins in citric acid-sodium citrate buffer solution to obtain blueberry anthocyanin solution; The steps for preparing a stable blueberry anthocyanin solution are as follows: At least one of the following is added to the blueberry anthocyanin solution: tamarind polysaccharide solution and enzymatically hydrolyzed tamarind polysaccharide. Stirring is then performed to combine the two solutions, resulting in a stable blueberry anthocyanin solution.

[0006] Preferably, the enzymatic hydrolysis includes: adding an acetate-sodium acetate buffer solution at pH=5 and β-galactosidase, and performing enzymatic hydrolysis at 40~60℃ for 20~40 minutes.

[0007] Preferably, the enzymatic hydrolysis includes: adding an acetate-sodium acetate buffer solution with pH=5 and cellulase, and performing enzymatic hydrolysis at 40~60℃ for 20~40 minutes.

[0008] Preferably, in the step of preparing the blueberry anthocyanin solution, the pH of the citric acid-sodium citrate buffer solution is 2-4.

[0009] Preferably, in the step of preparing the blueberry anthocyanin stable solution, the mass concentration ratio of blueberry anthocyanin to tamarind polysaccharide is 1~15:1~15.

[0010] Preferably, in the step of preparing the blueberry anthocyanin stable solution, the stirring speed is 100~300 rpm and the time is 10~50 min.

[0011] Preferably, in the step of preparing the blueberry anthocyanin stable solution, the compounding method is through non-covalent bonding.

[0012] Preferably, the non-covalent bonding is at least one of hydrogen bonding, hydrophobic interaction, and van der Waals forces.

[0013] Compared with existing technologies, the method for enhancing the anthocyanin performance of blueberries using tamarind polysaccharides provided in this application has at least the following beneficial effects: 1. This application provides a method for improving the performance of blueberry anthocyanins using tamarind polysaccharides. The method involves adding unhydrolyzed tamarind polysaccharides or tamarind polysaccharides treated with enzymes such as β-galactosidase to a blueberry anthocyanin solution and mixing them to obtain a stable blueberry anthocyanin solution. This improves the stability of blueberry anthocyanins in light, heat, and digestive systems, enhances antioxidant properties, and improves color.

[0014] 2. This application provides a method for improving the performance of blueberry anthocyanins using tamarind polysaccharide. By optimizing the mixing process of blueberry anthocyanin solution and tamarind polysaccharide, studies have shown that when the ratio of tamarind polysaccharide to blueberry anthocyanins is 1:2 and the mixture is stirred at 200 rpm for 40 minutes, the stability of blueberry anthocyanins can be significantly improved.

[0015] 3. This application provides a method for improving the performance of blueberry anthocyanins using tamarind polysaccharides. Through analysis techniques such as liquid chromatography, ultra-high performance liquid chromatography-mass spectrometry, and infrared spectroscopy, the composition of blueberry anthocyanins and tamarind polysaccharides is revealed, and it is shown that in a stable solution of blueberry anthocyanins, blueberry anthocyanins and tamarind polysaccharides form a complex through non-covalent bonds such as hydrogen bonds. Attached Figure Description

[0016] To more clearly illustrate the technical solutions in the specific embodiments of this application or the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this application. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0017] Figure 1The diagram shows the anthocyanin retention rates of the blueberry anthocyanin solution and three heat-stable blueberry anthocyanin solutions provided in Example 3 of this application after heat treatment at 90°C for 30 min, 60 min, 120 min, and 240 min. Figure 2 The diagram shows the anthocyanin retention rates of the blueberry anthocyanin solution and three heat-stable blueberry anthocyanin solutions provided in Example 3 of this application after heat treatment at 75°C for 30 min, 60 min, 120 min, and 240 min. Figure 3 The diagram shows the anthocyanin retention rates of the blueberry anthocyanin solution and three heat-stable blueberry anthocyanin solutions provided in Example 3 of this application after heat treatment at 60°C for 30 min, 60 min, 120 min, and 240 min. Figure 4 The blueberry anthocyanin solution and three portions of blueberry anthocyanin photostable solution provided in Example 4 of this application were placed in a light source with a light power of 8W and a light intensity of 28μW / cm². 2 A schematic diagram of anthocyanin retention rate after irradiation under ultraviolet light for 0-42 hours; Figure 5 The diagram shows the test results of the antioxidant properties of the blueberry anthocyanin solution, the blueberry anthocyanin antioxidant stabilizing solution with added tamarind polysaccharide, the blueberry anthocyanin antioxidant stabilizing solution with added β-galactosidase hydrolyzed tamarind polysaccharide, and the blueberry anthocyanin antioxidant stabilizing solution with added cellulase hydrolyzed tamarind polysaccharide, characterized by scavenging DPPH free radicals provided in Example 5 of this application. Figure 6 The diagram shows the test results of the antioxidant properties of the blueberry anthocyanin solution, the blueberry anthocyanin antioxidant stabilizing solution with added tamarind polysaccharide, the blueberry anthocyanin antioxidant stabilizing solution with added β-galactosidase hydrolyzed tamarind polysaccharide, and the blueberry anthocyanin antioxidant stabilizing solution with added cellulase hydrolyzed tamarind polysaccharide, characterized by the scavenging of ABTS free radicals provided in Example 5 of this application. Figure 7 This diagram illustrates the test results of the antioxidant properties characterized by the iron ion reducing ability of the blueberry anthocyanin solution, the blueberry anthocyanin antioxidant stabilizing solution with added tamarind polysaccharide, the blueberry anthocyanin antioxidant stabilizing solution with added β-galactosidase hydrolyzed tamarind polysaccharide, and the blueberry anthocyanin antioxidant stabilizing solution with added cellulase hydrolyzed tamarind polysaccharide provided in Example 5 of this application. Figure 8 This diagram illustrates the anthocyanin retention rates of the blueberry anthocyanin solution and three blueberry anthocyanin digestive system stabilizing solutions provided in Example 6 of this application during simulated saliva, simulated gastric juice, and simulated intestinal juice stages. Figure 9A schematic diagram of the anthocyanin retention rate of five heat-stable solutions of tamarind polysaccharide and blueberry anthocyanin with different ratios of blueberry anthocyanin provided in Example 7 of this application after heat treatment at 90°C for 30 min. Figure 10 A schematic diagram of the anthocyanin retention rate of five tamarind polysaccharide and blueberry anthocyanin heat-stable solutions with different stirring times provided in Example 7 of this application after heat treatment at 90°C for 30 min. Figure 11 The electron micrograph of the blueberry anthocyanin sample provided in Experimental Example 1 of this application, characterized by field emission scanning electron microscopy. Figure 12 The electron micrograph of the tamarind polysaccharide sample provided in Experimental Example 1 of this application, characterized by field emission scanning electron microscopy. Figure 13 The electron micrograph of the blueberry anthocyanin-tamarind polysaccharide complex provided in Experimental Example 1 of this application, characterized by field emission scanning electron microscopy. Figure 14 Infrared spectra of the tamarind polysaccharide sample, blueberry anthocyanin sample, and blueberry anthocyanin-tamarind polysaccharide complex sample provided in Experimental Example 1 of this application, obtained by infrared spectroscopy. Figure 5 , Figure 6 as well as Figure 7 In the study, the control group was a blueberry anthocyanin solution, experimental group 1 was a blueberry anthocyanin antioxidant stabilizing solution with added tamarind polysaccharide, experimental group 2 was a blueberry anthocyanin antioxidant stabilizing solution with added tamarind polysaccharide hydrolyzed by β-galactosidase, and experimental group 3 was a blueberry anthocyanin antioxidant stabilizing solution with added tamarind polysaccharide hydrolyzed by cellulase. Detailed Implementation

[0018] This application provides a method for improving the performance of blueberry anthocyanins using tamarind polysaccharides, which solves the current technical problem that the performance of blueberry anthocyanins is prone to decline.

[0019] The technical solutions of this application will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this application. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0020] Example 1

[0021] This embodiment analyzes the composition of tamarind polysaccharides and blueberry anthocyanins, respectively.

[0022] The compositional analysis of tamarind polysaccharide (TSP) included: A standard solution was prepared using mannose, ribose, rhamnose, glucuronic acid, galacturonic acid, N-acetylglucosamine, glucose, N-acetylglucosamine, galactose, xylose, arabinose, and fucose. Tamarind polysaccharide was added to 2.0 mL of 2 mol / L trifluoroacetic acid solution, sealed under nitrogen, and hydrolyzed at 120 °C for 10 h. 1.0 mL of the hydrolysate was taken, and after removing the trifluoroacetic acid by nitrogen blowing, it was redissolved in water to obtain the tamarind polysaccharide sample solution.

[0023] Prepare a Shimadzu LC-20AD chromatographic analysis system equipped with an Ultimate C18 column, column temperature 30℃, detection wavelength 250nm, flow rate 1.0mL / min, injection volume 20μL, mobile phase 0.05mol / L potassium dihydrogen phosphate solution-acetonitrile (83:17, v / v), and perform isocratic elution.

[0024] The results of the tamarind polysaccharide test are shown in Table 1. As can be seen from Table 1, tamarind polysaccharide is mainly composed of glucose (Glc), xylose (Xyl), and galactose (Gal), and contains a small amount of arabinose (Ara), indicating that it is a typical heteropolysaccharide. Further calculation and conversion based on the peak area of ​​each monosaccharide derivative yielded a molar ratio of glucose, xylose, and galactose of 3.4:1.3:1, indicating that glucose residues are dominant, while xylose and galactose are important components.

[0025] The compositional analysis of blueberry anthocyanins included: Prepare an ultra-high performance liquid chromatography-mass spectrometry (UPLC-Q-Orbitrap HRMS) instrument and a blueberry anthocyanin sample solution; equip the instrument with a Venusil ASB C18 column, column temperature 30℃, detection wavelength 520nm, injection volume 10μL, flow rate 0.8mL / min; mobile phases A and B are methanol and 12% formic acid aqueous solution, respectively, for gradient elution. The gradient elution program is as follows: 0.0~30.0 min, 6%~90% A; 30.0~31.0 min, 90%~95% A; 31.0~34.0 min, 95%~95% A; 34.0~37.0 min, 95%~6% A; 37.0~40.0 min, 6%~6% A; simultaneously set the ionization sources for positive and negative ion modes to +4.0kV and -3.0kV, respectively.

[0026] The results of the blueberry anthocyanin test are shown in Table 2; Table 2 includes the molecular formula, retention time, and parent ion ([M]). +The parent ion peak reflects the relative molecular mass of the compound, while the fragment ion peak usually originates from the desugaring reaction after glycosidic bond breakage and can be used to determine the glycosyl type; for example, the common neutral loss of 162 Da corresponds to hexose (glucose / galactose), and 132 Da corresponds to pentose (arabinose). Based on this and combined with the characteristic ions of the anthocyanin skeleton, this experiment found that blueberry anthocyanins are mainly composed of delphinidin, cyanidin, petunidin, and peonidin. The anthocyanin skeleton, composed of malvidin and other anthocyanins, forms glycosides with glucose, galactose, or arabinose. Overall, delphinidin and malvidin anthocyanins showed strong responses in the samples, suggesting they are among the main components of the blueberry anthocyanin system. Combining the compositional analysis results of tamarind polysaccharide and blueberry anthocyanin shown in Tables 1 and 2, it can be seen that delphinidin and other components in blueberry anthocyanins form glycosides with glucose and galactose, while tamarind polysaccharide contains glucose, galactose, and other components. This suggests that tamarind polysaccharide may interact with blueberry anthocyanins and stabilize the blueberry anthocyanins.

[0027] Table 1: Compositional Analysis Results of Tamarind Polysaccharides

[0028] Table 2: Compositional Analysis Results of Blueberry Anthocyanins

[0029] Example 2

[0030] Blueberry anthocyanins, as a natural pigment, need to maintain their ideal color during processing and storage. This embodiment provides a method for enhancing the color of blueberry anthocyanins using tamarind polysaccharide. The method includes the preparation steps of blueberry anthocyanin solution, tamarind polysaccharide solution, and blueberry anthocyanin color stabilizing solution.

[0031] The preparation steps for the blueberry anthocyanin solution include: dissolving laboratory-prepared blueberry anthocyanins in a citric acid-sodium citrate buffer solution at pH=3 to prepare a blueberry anthocyanin (BA) solution with a concentration of 0.1 mg / mL.

[0032] The preparation steps of tamarind polysaccharide solution include: dissolving tamarind polysaccharide solid in deionized water, sonicating for 30 min, and then magnetically stirring for 3-4 h to dissolve it, thereby obtaining tamarind polysaccharide (TSP) solution; and preparing tamarind polysaccharide (TSP) solutions with concentrations of 0.2 mg / mL, 0.5 mg / mL, 0.8 mg / mL, and 1.5 mg / mL respectively.

[0033] The preparation steps of the blueberry anthocyanin color-stabilized solution include: mixing an 0.1 mg / mL blueberry anthocyanin solution with equal volumes of 0.2 mg / mL, 0.5 mg / mL, 0.8 mg / mL and 1.5 mg / mL tamarind polysaccharide solutions, and allowing the mixture to stand for 30 minutes to obtain the blueberry anthocyanin color-stabilized solution.

[0034] The absorption spectra of blueberry anthocyanin solution and blueberry anthocyanin color-stabilized solution in the 300-700 nm range and the absorbance near 520 nm were measured using a multi-functional microplate reader. The absorption spectrum in the 300-700 nm range showed that the maximum absorption wavelength of the blueberry anthocyanin solution was approximately 518 nm. The maximum absorption wavelengths of the blueberry anthocyanin color-stabilized solutions, obtained by mixing the blueberry anthocyanin solution with 0.5 mg / mL, 0.8 mg / mL, and 1.5 mg / mL tamarind polysaccharide solutions, were approximately 519 nm, 520 nm, and 521 nm, respectively, showing an increase of 3 nm, indicating a redshift effect. The absorbance near 520 nm was used to characterize the color-enhancing effect of tamarind polysaccharide, with the color-enhancing effect (%) calculated as (A-A0) / A0×100, where A0 represents the absorbance of the blueberry anthocyanin solution and A represents the absorbance of the blueberry anthocyanin color-stabilized solution mixed with tamarind polysaccharide, as shown in Table 3. In Table 3, CK represents the blueberry anthocyanin solution. As can be seen from Table 3, the color-enhancing effect becomes more and more obvious as the concentration of tamarind polysaccharide solution increases. This indicates that tamarind polysaccharide can act as a good co-pigment, forming a stable complex with anthocyanins through a synergistic effect, effectively improving their color stability.

[0035] Blueberry anthocyanin solution and blueberry anthocyanin color-stabilizing solution were placed in a 12.5×12.5×45 quartz cuvette. The parameters were set to light source D65 and observation angle 10°. The CIELAB color characteristics of the samples were measured using a spectrophotometer, with distilled water as a control. The results are shown in Table 4, where CK represents the blueberry anthocyanin solution. Table 4 shows that as the amount of tamarind polysaccharide added increases, the a... The value (red chromaticity) increases and the color saturation increases (which can be reflected in chromaticity C). The increase indicates that anthocyanins are more fully expressed and the red color is more prominent. The increase in saturation value can make the sample present a more vivid and redder visual feature, thereby significantly improving the product's appearance appeal and sensory acceptance. At the same time, the increase in saturation means that the color is richer, purer, and has a higher overall color intensity, which is conducive to obtaining a stronger coloring effect at the same pigment level and enhancing the consistency and stability of the target hue. This indicates that tamarind polysaccharide improves the color quality of blueberry anthocyanins and provides a more favorable sensory basis for maintaining the ideal hue during subsequent processing and storage.

[0036] Table 3: Results of Color Enhancement Effect Test

[0037] Table 4: CIELAB color characteristic test results for different ratios of blueberry anthocyanins and tamarind polysaccharides

[0038] Example 3

[0039] Blueberry anthocyanins need to be protected during processing and storage to prevent degradation due to high temperatures and to possess thermal stability. This embodiment provides a method for improving the thermal stability of blueberry anthocyanins using tamarind polysaccharide. The method includes steps for preparing a blueberry anthocyanin solution, a tamarind polysaccharide solution, and a heat-stable blueberry anthocyanin solution.

[0040] The preparation steps of the blueberry anthocyanin solution include: using laboratory-prepared blueberry anthocyanins, dissolving them in a citric acid-sodium citrate buffer solution at pH=3 to prepare a blueberry anthocyanin (BA) solution with a concentration of 8 mg / mL.

[0041] The preparation steps of tamarind polysaccharide solution include: dissolving tamarind polysaccharide solid in deionized water, sonicating for 30 min, and then magnetically stirring for 3-4 h to dissolve it, obtaining a tamarind polysaccharide (TSP) solution with a concentration of 2 mg / mL; at the same time, dividing the 2 mg / mL tamarind polysaccharide solution into three portions, adding acetate-sodium acetate buffer to two portions to adjust the pH to 5, and adding 20 mg (200 U) of β-galactosidase (β-gal) and 10 mg (200 U) of cellulase (CEL) to the other two portions, reacting at 50℃ for 30 min, and then inactivating the enzymes by boiling water bath to obtain two enzymatically hydrolyzed tamarind polysaccharide solutions, TSP(β-gal) and TSP(CEL).

[0042] The preparation steps of the blueberry anthocyanin heat-stable solution include: mixing the blueberry anthocyanin solution with equal volumes of tamarind polysaccharide solution and two types of enzymatically hydrolyzed tamarind polysaccharides, and letting stand for 30 minutes to obtain the blueberry anthocyanin heat-stable solution.

[0043] Blueberry anthocyanin solution and three heat-stable blueberry anthocyanin solutions were heat-treated at 60℃, 75℃, and 90℃ for 30 min, 60 min, 120 min, and 240 min, respectively. The UV absorbance and retention rate of anthocyanins were measured after heat treatment. The anthocyanin retention rate results are shown below. Figure 1 , Figure 2 as well as Figure 3 As shown; Figures 1-3In the formula, the anthocyanin retention rate (%) is calculated as C / C0 × 100%, where C0 is the anthocyanin concentration of blueberries after heat treatment for 0 min, and C represents the anthocyanin concentrations after heat treatments of 30 min, 60 min, 120 min, and 240 min. The anthocyanin content of blueberries was determined using the pH differential method. Figures 1-3 It can be seen that at the same heat treatment temperature, the retention rate of anthocyanins in both the blueberry anthocyanin solution and the three heat-stable blueberry anthocyanin solutions gradually decreased with the extension of heat treatment time, indicating that the blueberry anthocyanins underwent thermal degradation and fading. Moreover, the thermal degradation and fading decreased even faster with the increase of heat treatment temperature. However, the addition of tamarind polysaccharide to the three heat-stable blueberry anthocyanin solutions alleviated the retention rate of anthocyanins and improved the thermal stability of blueberry anthocyanins.

[0044] Example 4

[0045] Blueberry anthocyanins need to be protected during processing and storage to prevent degradation due to light exposure and to possess photostability. This embodiment provides a method for improving the photostability of blueberry anthocyanins using tamarind polysaccharide. The method includes steps for preparing a blueberry anthocyanin solution, a tamarind polysaccharide solution, and a blueberry anthocyanin photostability solution.

[0046] The preparation steps of the blueberry anthocyanin solution include: using laboratory-prepared blueberry anthocyanins, dissolving them in a citric acid-sodium citrate buffer solution at pH=3 to prepare a blueberry anthocyanin (BA) solution with a concentration of 8 mg / mL.

[0047] The preparation steps of tamarind polysaccharide solution include: dissolving tamarind polysaccharide solid in deionized water, sonicating for 30 min, and then magnetically stirring for 3-4 h to dissolve it, obtaining a tamarind polysaccharide (TSP) solution with a concentration of 2 mg / mL; at the same time, dividing the 2 mg / mL tamarind polysaccharide solution into three portions, adding acetate-sodium acetate buffer to two portions to adjust the pH to 5, and adding 20 mg (200 U) of β-galactosidase (β-gal) and 10 mg (200 U) of cellulase (CEL) to the other two portions, reacting at 50℃ for 30 min, and then inactivating the enzymes by boiling water bath to obtain two enzymatically hydrolyzed tamarind polysaccharide solutions, TSP(β-gal) and TSP(CEL).

[0048] The preparation steps of the blueberry anthocyanin photostable solution include: mixing the blueberry anthocyanin solution with equal volumes of tamarind polysaccharide solution and two types of enzymatically hydrolyzed tamarind polysaccharides, and letting stand for 30 minutes to obtain the blueberry anthocyanin photostable solution.

[0049] The blueberry anthocyanin solution and three portions of the blueberry anthocyanin photostable solution were placed in a light source with a power of 8W and a light intensity of 28μW / cm². 2Irradiated under a UV lamp for 0–42 h; the UV absorbance and anthocyanin retention rate were measured after irradiation. The anthocyanin retention rate results are as follows: Figure 4 As shown; Figure 4 In the formula, anthocyanin retention rate (%) = C / C0 × 100%, where C0 is the anthocyanin concentration of blueberries after 0 min of light treatment, and C is the anthocyanin concentration of blueberries after a certain period of light treatment. The anthocyanin content of blueberries was determined using the pH differential method. Figure 4 It can be seen that with the extension of light treatment time, the anthocyanin retention rate in both the blueberry anthocyanin solution and the three blueberry anthocyanin photostable solutions gradually decreased, indicating that blueberry anthocyanins underwent photodegradation and fading. During short-term light exposure (6h), the addition of tamarind polysaccharide alleviated the anthocyanin retention in the three blueberry anthocyanin photostable solutions. However, during long-term light treatment (6h~42h), tamarind polysaccharide was detrimental to the anthocyanin retention in the blueberry anthocyanin solution; simultaneously, combined with... Figures 1-3 It can be seen that adding only tamarind polysaccharide is beneficial to improving the light stability of blueberry anthocyanins in the short term, while adding tamarind polysaccharide hydrolyzed by enzymes such as β-galactosidase is beneficial to improving the heat stability of blueberry anthocyanins. Therefore, different blueberry anthocyanin stable solutions can be prepared according to the time, light and heat conditions of the processing and storage process.

[0050] Example 5

[0051] The antioxidant properties of blueberry anthocyanins are one of their important effects. To avoid the degradation of blueberry anthocyanins affecting their antioxidant properties, this embodiment provides a method for enhancing the antioxidant properties of blueberry anthocyanins using tamarind polysaccharides. The method includes the preparation steps of blueberry anthocyanin solution, tamarind polysaccharide solution, and blueberry anthocyanin antioxidant stabilizing solution.

[0052] The preparation steps of the blueberry anthocyanin solution include: using laboratory-prepared blueberry anthocyanins, dissolving them in a citric acid-sodium citrate buffer solution at pH=3 to prepare a blueberry anthocyanin (BA) solution with a concentration of 8 mg / mL.

[0053] The preparation steps of tamarind polysaccharide solution include: dissolving tamarind polysaccharide solid in deionized water, sonicating for 30 min, and then magnetically stirring for 3-4 h to dissolve it, obtaining a tamarind polysaccharide (TSP) solution with a concentration of 2 mg / mL; at the same time, dividing the 2 mg / mL tamarind polysaccharide solution into three portions, adding acetate-sodium acetate buffer to two portions to adjust the pH to 5, and adding 20 mg (200 U) of β-galactosidase (β-gal) and 10 mg (200 U) of cellulase (CEL) to the other two portions, reacting at 50℃ for 30 min, and then inactivating the enzymes by boiling water bath to obtain two enzymatically hydrolyzed tamarind polysaccharide solutions, TSP(β-gal) and TSP(CEL).

[0054] The preparation steps of the blueberry anthocyanin antioxidant stabilizing solution include: mixing the blueberry anthocyanin solution with equal volumes of tamarind polysaccharide solution and two types of enzymatically hydrolyzed tamarind polysaccharides, and letting stand for 30 minutes to obtain the blueberry anthocyanin antioxidant stabilizing solution.

[0055] Blueberry anthocyanin solution was used as the control group sample. A blueberry anthocyanin antioxidant stabilizing solution containing tamarind polysaccharide was used as experimental group 1. A blueberry anthocyanin antioxidant stabilizing solution containing tamarind polysaccharide hydrolyzed by β-galactosidase was used as experimental group 2. A blueberry anthocyanin antioxidant stabilizing solution containing tamarind polysaccharide hydrolyzed by cellulase was used as experimental group 3. 300 μL of each sample was thoroughly mixed with 2.7 mL of 0.1 mM DPPH (dissolved in 95% ethanol). Simultaneously, 50 μL of each sample was mixed with 2 mL of ABTS. + The working solution is thoroughly mixed, ABTS + The preparation process of the working solution includes: diluting the ABTS solution with anhydrous ethanol until its absorbance at a wavelength of 734 nm reaches 0.70 ± 0.02, thus obtaining ABTS. + Working solution; separately, take 100 μL of sample and mix thoroughly with 3 mL of FRAP working solution; the preparation process of FRAP working solution includes: mixing 10 mM TPTZ solution (dissolved in 40 mM HCl), 20 mM ferric chloride solution and 0.1 M acetate buffer in a ratio of 1:1:10 (v:v:v) to obtain FRAP working solution; then place the solution in the dark for 30 min, then transfer 200 μL of the solution to a 96-well plate, and measure the absorbance at 517 nm, 734 nm and 593 nm using a multi-mode microplate reader, and quantify the antioxidant capacity of the sample using Trolox equivalents, the results are as follows. Figure 5 , Figure 6 as well as Figure 7 As shown; from Figures 5-7 It can be seen that the blueberry anthocyanin solution exhibits strong antioxidant activity. When tamarind polysaccharide or enzymatically hydrolyzed tamarind polysaccharide solution is added, its antioxidant activity is further enhanced, effectively scavenging free radicals such as DPPH and ABTS, and the ferric reducing power (FRAP) is strengthened. Enzymatically hydrolyzed tamarind polysaccharide may have changed in molecular weight or conformation due to enzymatic hydrolysis, resulting in different binding forms with blueberry anthocyanins. This may have masked some reaction sites of blueberry anthocyanins, thus limiting the improvement of the system's antioxidant capacity. However, its antioxidant performance is still higher than that of blueberry anthocyanin solution alone. Therefore, the blueberry anthocyanin antioxidant stabilizing solution provided in this application can provide stable antioxidant performance and alleviate the decline in antioxidant performance caused by the degradation of blueberry anthocyanins.

[0056] Example 6

[0057] This embodiment provides a method for improving the stability of blueberry anthocyanins in the digestive system using tamarind polysaccharide. The method includes the steps of preparing a blueberry anthocyanin solution, preparing a tamarind polysaccharide solution, and preparing a blueberry anthocyanin digestive system stabilizing solution.

[0058] The preparation steps of the blueberry anthocyanin solution include: using laboratory-prepared blueberry anthocyanins, dissolving them in a citric acid-sodium citrate buffer solution at pH=3 to prepare a blueberry anthocyanin (BA) solution with a concentration of 8 mg / mL.

[0059] The preparation steps of tamarind polysaccharide solution include: dissolving tamarind polysaccharide solid in deionized water, sonicating for 30 min, and then magnetically stirring for 3-4 h to dissolve it, obtaining a tamarind polysaccharide (TSP) solution with a concentration of 2 mg / mL; at the same time, dividing the 2 mg / mL tamarind polysaccharide solution into three portions, adding acetate-sodium acetate buffer to two portions to adjust the pH to 5, and adding 20 mg (200 U) of β-galactosidase (β-gal) and 10 mg (200 U) of cellulase (CEL) to the other two portions, reacting at 50℃ for 30 min, and then inactivating the enzymes by boiling water bath to obtain two enzymatically hydrolyzed tamarind polysaccharide solutions, TSP(β-gal) and TSP(CEL).

[0060] The preparation steps of the blueberry anthocyanin digestive system stable solution include: mixing the blueberry anthocyanin solution with equal volumes of tamarind polysaccharide solution and two types of enzymatically hydrolyzed tamarind polysaccharides, and letting stand for 30 minutes to obtain the blueberry anthocyanin digestive system stable solution.

[0061] Take 10 mL of blueberry anthocyanin solution and three portions of blueberry anthocyanin digestive system stabilizing solution, and mix them thoroughly with 2 mL of simulated saliva. Shake at 37°C and 120 rpm for 5 min in the dark to obtain simulated saliva digestive fluid. Add 4 mL of simulated gastric juice to the simulated saliva digestive fluid, mix thoroughly, and shake at 37°C and 120 rpm for 120 min in the dark to obtain simulated gastric juice digestive fluid. Add 5.3 mL of small intestinal reserve fluid and 2.6 mL of bile to the simulated gastric juice digestive fluid to obtain simulated intestinal juice digestive fluid. Mix thoroughly and shake at 37°C and 120 rpm in the dark. The sample was shaken in a shaker for 120 min to obtain simulated intestinal digestive fluid. 3 mL of each of the simulated saliva, simulated gastric juice, and simulated intestinal digestive fluid were collected, centrifuged at 10000 r / min for 5 min, and filtered through a membrane. The anthocyanin content in the simulated saliva, simulated gastric juice, and simulated intestinal juice stages was determined by pH differential method. The anthocyanin retention rate (%) was calculated as C / C0 × 100%, where C0 is the anthocyanin concentration of blueberries before treatment, and C is the anthocyanin concentration of the simulated saliva, simulated gastric juice, or simulated intestinal digestive fluid. The results are shown below. Figure 8 As shown; from Figure 8It can be seen that the retention rates of blueberry anthocyanins in the blueberry anthocyanin solution and the three blueberry anthocyanin digestive system stabilization solutions differed significantly in the oral saliva, gastric juice, and intestinal juice stages, with the most significant decrease observed in the small intestine stage. This phenomenon is related to the sensitivity of anthocyanins to the acid-base conditions of the system. Under near-neutral conditions, blueberry anthocyanins are more prone to structural transformation and further degradation. Therefore, compared to the oral saliva and gastric juice stages, the small intestine stage is often where blueberry anthocyanin loss is more concentrated. Furthermore, it can be seen that compared to the blueberry anthocyanin solution, the addition of tamarind polysaccharide... The blueberry anthocyanin digestive system stabilized solution showed improved anthocyanin retention rates in simulated saliva, gastric juice, and intestinal juice stages. This indicates that tamarind polysaccharides and blueberry anthocyanins form a stable complex, reducing the exposure of blueberry anthocyanins in the digestive medium and thus slowing down their structural transformation and loss. In contrast, tamarind polysaccharides treated with β-galactosidase or cellulase may have disrupted the structure of tamarind polysaccharides, reducing their ability to form stable complexes or provide a shielding effect, making it more difficult to maintain a high anthocyanin retention rate in the small intestine.

[0062] Example 7

[0063] To further investigate the effect of the preparation process of the heat-stable solution of blueberry anthocyanins on the heat stability of blueberry anthocyanins, this embodiment provides a method for improving the heat stability of blueberry anthocyanins using tamarind polysaccharide. The method includes the preparation steps of tamarind polysaccharide solution, the preparation steps of blueberry anthocyanin solution, and the preparation steps of blueberry anthocyanin heat-stable solution.

[0064] The preparation steps of the tamarind polysaccharide solution include: In order to ensure that the prepared tamarind polysaccharide solution has regulatory compliance and practical application feasibility, this embodiment limits the maximum concentration of the prepared tamarind polysaccharide to 2 mg / mL. The process is to dissolve the tamarind polysaccharide solid in deionized water, sonicate for 30 min, and then use magnetic stirring for 3-4 h to dissolve it, so as to obtain a tamarind polysaccharide (TSP) solution with a concentration of 2 mg / mL.

[0065] The preparation steps of blueberry anthocyanin solution include: using laboratory-prepared blueberry anthocyanins, dissolving them in a citric acid-sodium citrate buffer solution at pH=3, and preparing blueberry anthocyanin (BA) solutions with concentrations of 1 mg / mL, 2 mg / mL, 3 mg / mL, 4 mg / mL, and 5 mg / mL respectively.

[0066] The preparation steps for the heat-stable solution of blueberry anthocyanins include: Tamarind polysaccharide solution was mixed with equal volumes of blueberry anthocyanin solutions at concentrations of 1 mg / mL, 2 mg / mL, 3 mg / mL, 4 mg / mL, and 5 mg / mL, respectively. The mixture was stirred at 200 rpm for 40 min and then allowed to stand for 30 min to obtain five heat-stable blueberry anthocyanin solutions with different ratios of tamarind polysaccharide and blueberry anthocyanin.

[0067] Tamarind polysaccharide solution and blueberry anthocyanin solution with a concentration of 4 mg / mL were mixed at 200 rpm for 10 min, 20 min, 30 min, 40 min and 50 min respectively, and then allowed to stand for 30 min to obtain five heat-stable solutions of blueberry anthocyanin with different stirring times.

[0068] Five portions of heat-stable blueberry anthocyanin solutions with different ratios of tamarind polysaccharide and blueberry anthocyanin were heat-treated at 90℃ for 30 min. The UV absorbance and retention rate of the anthocyanins after heat treatment were measured. The anthocyanin retention rate results are shown below. Figure 9 As shown; Figure 9 In the formula, the anthocyanin retention rate (%) is calculated as C / C0 × 100%, where C0 is the anthocyanin concentration of blueberries after 0 min of heat treatment, and C is the anthocyanin concentration of blueberries after 30 min of heat treatment. The anthocyanin content of blueberries was determined using the pH differential method. Figure 9 It can be seen that when a tamarind polysaccharide solution with a concentration of 2 mg / mL is mixed with a blueberry anthocyanin solution with a concentration of less than 4 mg / mL, the anthocyanin retention rate increases with the increase of the blueberry anthocyanin solution concentration. However, when the concentration of the blueberry anthocyanin solution increases to 5 mg / mL, the amount of tamarind polysaccharide solution is too small to combine all the blueberry anthocyanins, and the protective ability is slightly reduced, resulting in a decrease in the anthocyanin retention rate.

[0069] Five portions of tamarind polysaccharide and blueberry anthocyanin heat-stable solutions with different stirring times were placed in 90℃ for 30 min for heat treatment. The UV absorbance and anthocyanin retention rate were measured after heat treatment. The anthocyanin retention rate results are as follows: Figure 10 As shown; Figure 10 In the formula, the anthocyanin retention rate (%) is calculated as C / C0 × 100%, where C0 is the anthocyanin concentration of blueberries after 0 min of heat treatment, and C is the anthocyanin concentration of blueberries after 30 min of heat treatment. The anthocyanin content of blueberries was determined using the pH differential method. Figure 10 It can be seen that within 0-40 minutes, the extension of stirring time promotes the complexation of tamarind polysaccharides and blueberry anthocyanins, thereby increasing the anthocyanin retention rate; combined with Figure 9It can be seen that when the ratio of tamarind polysaccharide to blueberry anthocyanin in the heat-stable solution is 1:2, and the solution is stirred at 200 rpm for 40 min, it can provide excellent heat stability of blueberry anthocyanins.

[0070] Experimental Example 1

[0071] This experiment characterized the morphology and complexation of tamarind polysaccharides and blueberry anthocyanins in a stable solution of blueberry anthocyanins using infrared spectroscopy and field emission scanning electron microscopy.

[0072] The sample preparation process included: preparing a 2 mg / mL tamarind polysaccharide solution and a 4 mg / mL blueberry anthocyanin solution; mixing equal volumes of the 2 mg / mL tamarind polysaccharide solution and the 4 mg / mL blueberry anthocyanin solution at 200 rpm for 40 min and allowing to stand for 30 min to obtain a stable blueberry anthocyanin solution; subsequently, the tamarind polysaccharide solution, the blueberry anthocyanin solution, and the stable blueberry anthocyanin solution were freeze-dried using a freeze dryer to obtain samples of tamarind polysaccharide, blueberry anthocyanin, and blueberry anthocyanin-tamarind polysaccharide complex.

[0073] The field emission scanning electron microscopy (FET) characterization process included: observing three samples—tamarind polysaccharide, blueberry anthocyanins, and blueberry anthocyanin-tamarind polysaccharide complex—using a field emission scanning electron microscope at an operating voltage of 5.0 kV. The results are as follows: Figure 11 , Figure 12 , Figure 13 As shown; from Figure 11 It can be seen that blueberry anthocyanins are irregularly shaped spherical particles, while Figure 12 Tamarind polysaccharides exhibit a fibrous or platy structure, characterized by its slender, smooth, dense, and regularly shaped structure. Figure 13 The blueberry anthocyanin-tamarind polysaccharide complexes shown formed larger, more coiled, dense, blocky aggregates, exhibiting layered, coiled sheets or folds, which visually demonstrates that they interacted and bonded together.

[0074] The infrared spectroscopy characterization process included: adding three samples—tamarind polysaccharide, blueberry anthocyanins, and blueberry anthocyanin-tamarind polysaccharide complex—to KBr pellets, and then scanning the 4000-400 cm⁻¹ range using Fourier transform infrared spectroscopy. -1 The spectrum covers a range with a resolution of 4 cm⁻¹. -1 The scanning frequency was 32 times, and its infrared spectrum is as follows: Figure 14 As shown; from Figure 14 It can be seen that the blueberry anthocyanin sample was at 1632.7 cm⁻¹ -1 With 1450.6cm -1The presence of a characteristic absorption peak nearby can serve as a fingerprint signal for the vibrational correlation between the aromatic skeleton and benzopyran ring of flavonoid derivatives, and this peak is also observed at 1232.8 cm⁻¹. -1 With 1074.8cm -1 The nearby absorption peaks are mainly related to the CH bending vibration of the aromatic ring in anthocyanin molecules and the stretching vibrations associated with the pyran ring / glycoside structure, indicating that the sample has typical aromatic ring-glycosyl structure characteristics of anthocyanins; while the tamarind polysaccharide sample shows an absorption peak at 3435.8 cm⁻¹. -1 A strong and broad absorption band is observed at 2925.4 cm⁻¹, which is a typical characteristic peak of the hydroxyl stretching vibration in polysaccharides; -1 The presence of weak peaks in the vicinity can be attributed to the asymmetric stretching vibration of the CH bond. Additionally, at 1000-1200 cm⁻¹... -1 A relatively broad absorption band was observed in the region, typically associated with COH stretching vibrations and COC glycosidic bond vibrations, reflecting the presence of the polysaccharide backbone and glycosidic bond structure. However, compared to blueberry anthocyanin or tamarind polysaccharide samples, the OH characteristic band of the freeze-dried blueberry anthocyanin stable solution sample increased from 3435.8 cm⁻¹. -1 The redshift to a lower wavenumber was achieved at 3427.9 cm. -1 The results suggest that the hydrogen bonding environment around the hydroxyl groups changes after complexation, indicating that tamarind polysaccharides and blueberry anthocyanins may form intermolecular interactions mainly based on hydrogen bonds. Meanwhile, blueberry anthocyanins at 1599.5 cm⁻¹... -1 The nearby characteristic peak shifted to 1591.6 cm⁻¹ after recombination. -1 The accompanying peak shape changes indicate that the complexation process altered the local chemical environment and vibrational modes near the aromatic skeleton of blueberry anthocyanins. Based on the combined peak position shift and peak shape changes, it can be inferred that the complexation of tamarind polysaccharides and blueberry anthocyanins mainly relies on non-covalent interactions, primarily hydrogen bonds, possibly accompanied by hydrophobic interactions / van der Waals forces, thereby promoting the formation of the complex system and improving its structural stability.

[0075] The above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application.

Claims

1. A method for enhancing the anthocyanin properties of blueberries using tamarind polysaccharides, characterized in that, Includes the following steps: Tamarind polysaccharide is dissolved in water to obtain a tamarind polysaccharide solution, or tamarind polysaccharide is dissolved in water and then enzymatically hydrolyzed to obtain an enzymatically hydrolyzed tamarind polysaccharide solution. Blueberry anthocyanins were dissolved in a citric acid-sodium citrate buffer solution to obtain a blueberry anthocyanin solution; At least one of the following, namely tamarind polysaccharide solution and enzymatically hydrolyzed tamarind polysaccharide, is added to blueberry anthocyanin solution and stirred to form a compound, thereby obtaining a stable blueberry anthocyanin solution.

2. The method for enhancing the anthocyanin properties of blueberries using tamarind polysaccharides according to claim 1, characterized in that, The enzymatic hydrolysis includes adding an acetate-sodium acetate buffer solution at pH=5 and β-galactosidase, and performing enzymatic hydrolysis at 40~60℃ for 20~40 minutes.

3. The method for enhancing the anthocyanin properties of blueberries using tamarind polysaccharides according to claim 1, characterized in that, The enzymatic hydrolysis process includes adding an acetate-sodium acetate buffer solution at pH 5 and cellulase, and then performing enzymatic hydrolysis at 40-60°C for 20-40 minutes.

4. The method for enhancing the anthocyanin properties of blueberries using tamarind polysaccharides according to claim 1, characterized in that, The pH of the citric acid-sodium citrate buffer solution is 2-4.

5. The method for enhancing the anthocyanin properties of blueberries using tamarind polysaccharides according to claim 1, characterized in that, The mass concentration ratio of blueberry anthocyanins to tamarind polysaccharides is 1~15:1~15.

6. The method for enhancing the anthocyanin properties of blueberries using tamarind polysaccharides according to claim 1, characterized in that, The stirring rate is 100~300 rpm, and the time is 10~50 min.

7. The method for enhancing the anthocyanin properties of blueberries using tamarind polysaccharides according to claim 1, characterized in that, The composite method is through non-covalent bonding.

8. A method for enhancing the anthocyanin properties of blueberries using tamarind polysaccharides according to claim 7, characterized in that, The non-covalent bonding is at least one of hydrogen bonding, hydrophobic interaction, and van der Waals forces.

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