Method for enhancing interaction between starch and polyphenol by utilizing starch phosphorylation

Abstract

The invention provides a method for enhancing interaction between starch and polyphenol by utilizing starch phosphorylation. The method comprises the following steps: reacting natural starch with a phosphorylation agent to obtain phosphorylated starch; adding the phosphorylated starch into an aqueous solution, adding polyphenol into the obtained phosphorylated starch solution, and storing the obtained phosphorylated starch / polyphenol mixture at low temperature. Natural starch is subjected to phosphorylation treatment under different pH conditions, the content of phosphate groups in the starch is increased, then the treated starch and polyphenol are blended in an aqueous solution to be combined, and the purposes of improving the stability of the polyphenol and achieving protection and slow release of the polyphenol are achieved.

Description

Technical Field

[0001] The present invention belongs to the technical field of food science and engineering, and specifically relates to a method for strengthening the interaction between starch and polyphenols by starch phosphorylation. Background Art

[0002] Polyphenols are secondary metabolites of plants such as fruits and vegetables, and have effects such as antioxidant, anti-tumor, antibacterial, anti-inflammatory and lipid-lowering. However, polyphenols have poor stability and are extremely susceptible to factors such as processing methods, pH, temperature, light, oxygen, enzymes, sulfur dioxide, metal ions, etc. during processing and storage, resulting in degradation, which in turn affects the color and quality of products. Therefore, protecting and improving the stability of polyphenols is the key to ensuring product quality, and it is also a hot and difficult point in the research field of food science.

[0003] Forming a complex through the interaction between macromolecules and polyphenols is an effective way to improve the stability of polyphenols. Among them, natural starch has broad application prospects as a carrier for encapsulating and delivering polyphenols due to its wide source, low price and unique properties. Natural starch can form V-type complexes or / and non-V-type complexes with polyphenols through non-covalent bonds such as electrostatic interaction, hydrogen bond and hydrophobic interaction, thereby playing a role in protecting polyphenols. However, the binding rate between natural starch and polyphenols is relatively low. Therefore, finding a method to strengthen the interaction between the two has become an urgent problem to be solved. Summary of the Invention

[0004] In order to solve the above technical problems, the present invention provides a method for strengthening the interaction between starch and polyphenols by starch phosphorylation.

[0005] The method for strengthening the interaction between starch and polyphenols by starch phosphorylation provided by the present invention includes the following steps: 1) React natural starch with a phosphorylation agent to obtain phosphorylated starch; 2) Add the phosphorylated starch into an aqueous solution, add polyphenols to the obtained phosphorylated starch solution, and store the obtained phosphorylated starch / polyphenol mixture at low temperature. In step 1) of the above method, the natural starch can be at least one of potato starch, yam starch, and cassava starch, specifically potato starch; The phosphorylation agent can be any one of sodium tripolyphosphate and sodium trimetaphosphate or a mixture of the two. Specifically, the phosphorylation agent is a mixture of sodium trimetaphosphate and sodium tripolyphosphate, and the mass ratio of sodium trimetaphosphate to sodium tripolyphosphate can be 50-150:1; The reaction uses anhydrous sodium sulfate as a catalyst; In an embodiment of the present invention, the phosphorylation agent is a mixture composed of sodium trimetaphosphate and sodium tripolyphosphate in a mass ratio of 99:1; The mass ratio of the natural starch to the phosphorylating agent can be: (5 - 50):1; The mass ratio of the natural starch to the anhydrous sodium sulfate can be: (15 - 25):1, specifically 20:1; The pH of the reaction system can be 6 - 11, specifically 6, 9, 11, and more specifically 11; The reaction time can be 30 - 90 min, specifically 60 min; The reaction is carried out under stirring; After the reaction, it further includes the operations of drying the obtained reaction system at low temperature until the water content is 15% - 20% and then carrying out a high-temperature reaction. Among them, the temperature of the low-temperature drying can be 30 - 50 °C, specifically 46 °C; The temperature of the high-temperature reaction can be 130 - 150 °C, the time can be 1.5 - 3 h, specifically reacting at 146 °C for 2 h.

[0006] After the high-temperature reaction, it further includes: after the sample is cooled, adding distilled water, mixing evenly, centrifuging the obtained suspension, removing the supernatant, adding distilled water to the solid residue and mixing evenly, adjusting the pH value to 6 - 7 (specifically 6.5), repeating the above operations multiple times, and drying to obtain phosphorylated starch. Among them, the drying temperature can be 30 - 50 °C, the time can be 15 - 25 h, specifically drying at 46 °C for 20 h.

[0007] In step 2) of the above method, the aqueous solution is at least one of pure water or buffer systems such as hydrochloric acid aqueous solution, citric acid aqueous solution, phosphate solution, etc., and the pH of the aqueous solution can be 3 - 7; The mass ratio of the aqueous solution to the natural starch in step 1) can be: 1:(0.001 - 0.1); The type of the polyphenol can be polyphenol monomers such as ferulic acid, epigallocatechin gallate, (+)-catechin, cyanidin-3-O-glucoside, etc., or a mixture or crude extract of polyphenols; The polyphenol concentration in the obtained system can be 10 -6 -10 -1 g / L; The temperature of the low-temperature storage can be 0 - 10 °C.

[0008] The above method can further include the operation of centrifuging and separating the system after low-temperature storage to collect the phosphorylated starch-polyphenol liquid complex; The above operation can further include the operation of freeze-drying the obtained phosphorylated starch-polyphenol liquid complex to obtain a complex solid; The above-mentioned phosphorylated starch-polyphenol liquid complex, complex solid and their applications in the field of food processing also fall within the protection scope of the present invention.

[0009] The above-mentioned application of phosphorylated starch enhancing the interaction with polyphenols also falls within the protection scope of the present invention.

[0010] The said application is the application of the method of the interaction between the above-mentioned phosphorylated starch and polyphenols in the processing and storage of polyphenol-rich foods.

[0011] The present invention phosphorylates natural starch under different pH conditions to increase the content of phosphate groups in the starch, and then blends the treated starch with polyphenols in an aqueous solution for combination, so as to achieve the purpose of improving the stability of polyphenols and realizing the protection and slow release of polyphenols.

[0012] The beneficial effects of the present invention are as follows: (1) By phosphorylating the starch, the present invention increases the content of phosphate groups in the starch, promotes the combination of polyphenols and starch through non-covalent bonds such as electrostatic interaction, plays a role in protecting and slowly releasing polyphenols, and helps the application of starch and polyphenols in different food processing fields; (2) The phosphorylation treatment in the present invention improves the binding rate of starch and polyphenols, which helps to better exert the beneficial physiological functions of polyphenols on the human body. Specific embodiments

[0013] The present invention will be further described in detail below in combination with specific embodiments. The given embodiments are only for clarifying the present invention, rather than limiting the scope of the present invention. The following provided embodiments can be used as a guide for those of ordinary skill in the art to make further improvements, and do not constitute any limitation to the present invention in any way.

[0014] In the experimental methods in the following embodiments, unless otherwise specified, they are all conventional methods, carried out according to the techniques or conditions described in the literature in this field or according to the product instructions. The materials, reagents, etc. used in the following embodiments, unless otherwise specified, can all be obtained from commercial channels.

[0015] The method for the interaction between phosphorylated starch and polyphenols provided by the present invention includes the following steps: 1) React natural starch with a phosphorylating agent to obtain phosphorylated starch, thereby increasing the phosphate groups in the starch and the number of negative charges; 2) Add the phosphorylated starch into an aqueous solution, add polyphenols to the obtained phosphorylated starch solution, and store the obtained phosphorylated starch / polyphenol mixture at a low temperature; In the above method step 1), the natural starch can be at least one of potato starch, yam starch, and cassava starch, and specifically can be potato starch; The phosphorylating agent can be any one of sodium tripolyphosphate and sodium metaphosphate or a mixture of both. The reaction uses anhydrous sodium sulfate as a catalyst. The mass ratio of the natural starch to the phosphorylating agent can be: (5 - 50):1. The mass ratio of the natural starch to anhydrous sodium sulfate can be: (15 - 25):1. The pH of the reaction system can be 6 - 11, specifically 6, 9, or 11. The reaction time can be 30 - 90 min. The reaction is carried out under stirring. After the reaction ends, it further includes the operations of drying the obtained reaction system at a low temperature until the water content is 15% - 20% and then carrying out a high-temperature reaction. Among them, the temperature of the low-temperature drying can be 30 - 50 °C, specifically 46 °C. The temperature of the high-temperature reaction can be 130 - 150 °C, and the time can be 1.5 - 3 h, specifically reacting at 146 °C for 2 h.

[0016] After the high-temperature reaction ends, it further includes: after the sample is cooled, adding distilled water, mixing evenly, centrifuging the obtained suspension, removing the supernatant, adding distilled water to the solid residue and mixing evenly, adjusting the pH value to 6 - 7 (specifically 6.5), repeating the above operations multiple times, and drying to obtain phosphorylated starch. Among them, the temperature of the drying can be 30 - 50 °C, and the time can be 15 - 25 h, specifically drying at 46 °C for 20 h.

[0017] In step 2) of the above method, the aqueous solution is at least one of pure water or a buffer system such as hydrochloric acid aqueous solution, citric acid aqueous solution, and phosphate solution, and the pH of the aqueous solution can be 3 - 7. The mass ratio of the aqueous solution to the phosphorylated starch can be: 1:(0.001 - 0.1). The type of the polyphenol can be a polyphenol monomer, such as ferulic acid, epigallocatechin gallate, (+)-catechin, cyanidin - 3 - O - glucoside, etc., or a mixture or crude extract of polyphenols. The polyphenol concentration in the obtained system can be 10 -6 -10 -1 g / L, specifically 0.1 g / L. The temperature of the low-temperature storage can be 0 - 10 °C.

[0018] The above method can further include the operation of centrifuging and separating the system after low-temperature storage to collect the phosphorylated starch-polyphenol liquid complex. The above operation may further include an operation of freeze-drying the obtained phosphorylated starch-polyphenol liquid complex to obtain a solid complex; The above phosphorylated starch-polyphenol liquid complex, solid complex and their applications in the field of food processing also belong to the protection scope of the present invention.

[0019] The above application of starch phosphorylation to enhance the interaction between starch and polyphenols also belongs to the protection scope of the present invention.

[0020] The application of the above method for starch phosphorylation to enhance the interaction between starch and polyphenols in the processing and storage of polyphenol-rich foods also belongs to the protection scope of the present invention.

[0021] Main materials and instruments for the examples Potato starch was purchased from Sigma Chemical Co., and cyanidin-3-O-glucoside was purchased from Shanghai Tongtian Biotechnology Co., Ltd.; electronic pH meter, magnetic stirrer, oven, centrifuge, high performance liquid chromatograph, automatic freeze substitution instrument, etc.

[0022] Example 1: Preparation of phosphorylated potato starch under phosphorylation conditions at pH 6 (1) Weigh 10 g of potato starch, 0.5 g of anhydrous Na2SO4 and 10.5% of sodium trimetaphosphate / sodium tripolyphosphate (STMP / STPP, 99 / 1, w / w, 1.05 g) into 14 ml of distilled water; (2) Adjust the pH to 6 with 0.2 M HCl and 0.2 M NaOH; (3) Stir the whole suspension at room temperature for 60 min; (4) Dry the suspension at 46 °C until the moisture content is 15%; (5) Heat at 146 °C for 2 h; (6) After the sample is cooled, add 70 mL of distilled water and vortex to mix well. Centrifuge the suspension at 3500 g for 10 min. After removing the supernatant, add 120 mL of distilled water to the solid residue and mix well. Adjust the pH value to 6.5 with 0.2 M NaOH solution; (7) Repeat the washing and centrifugation in step (6) three times, and finally dry at 46 °C for 20 h to obtain the phosphorylated product.

[0023] Example 2: Preparation of phosphorylated potato starch under phosphorylation conditions at pH 9 (1) Weigh 10 g of potato starch, 0.5 g of anhydrous Na2SO4 and 10.5% of sodium trimetaphosphate / sodium tripolyphosphate (STMP / STPP, 99 / 1, w / w) into 14 ml of distilled water; (2) Adjust the pH to 9 with 0.2 M HCl and 0.2 M NaOH; (3) Stir the whole suspension at room temperature for 60 min; (4) Dry the suspension at 46 °C until the moisture content is 15%; (5) Heat at 146 °C for 2 h; (6) After the sample cools, add 70 mL of distilled water and vortex to mix evenly. Centrifuge the suspension at 3500 g for 10 min. After removing the supernatant, add 120 mL of distilled water to the solid residue and mix evenly. Adjust the pH value to 6.5 with 0.2 M NaOH solution; (7) Repeat the washing and centrifugation in step (6) three times, and finally dry at 46 °C for 20 h to obtain the phosphorylated product.

[0024] Example 3. Preparation of phosphorylated potato starch under phosphorylation conditions at pH 11 (1) Weigh 10 g of potato starch, 0.5 g of anhydrous Na2SO4, and 10.5% of sodium trimetaphosphate / sodium tripolyphosphate (STMP / STPP, 99 / 1, w / w) into 14 ml of distilled water; (2) Adjust the pH to 11 with 0.2 M HCl and 0.2 M NaOH; (3) Stir the whole suspension at room temperature for 60 min; (4) Dry the suspension at 46 °C until the moisture content is 15%; (5) Heat at 146 °C for 2 h; (6) After the sample cools, add 70 mL of distilled water and vortex to mix evenly. Centrifuge the suspension at 3500 g for 10 min. After removing the supernatant, add 120 mL of distilled water to the solid residue and mix evenly. Adjust the pH value to 6.5 with 0.2 M NaOH solution; (7) Repeat the washing and centrifugation in step (6) three times, and finally dry at 46 °C for 20 h to obtain the phosphorylated product.

[0025] Example 4. Take the combination of phosphorylated potato starch and cyanidin-3-O-glucoside as an example Weigh 0.1 g of phosphorylated potato starch and add it to 9 mL of hydrochloric acid aqueous solution (pH = 3). Add 1 mL of cyanidin-3-O-glucoside (1 mg / mL, prepared with hydrochloric acid water at pH = 3) to the starch solution. Store at 4 °C for 4 h to obtain the complex.

[0026] Vortex the sample intermittently. Take 0.2 mL of the sample and mix it with 3.0 mL of chromatographic grade anhydrous methanol to elute the unbound cyanidin-3-O-glucoside. After mixing, centrifuge at 10000 g for 10 min.

[0027] High performance liquid chromatography elution method: Take 1 mL of the supernatant, filter it through a 0.45 μm filter membrane, and inject it into a brown injection vial. The set detection wavelength is 520 nm, the column temperature is 35 °C, and the injection volume is 10 μL. Mobile phase A consists of formic acid water with a mass concentration of 5%, and phase B consists of acetonitrile. The gradient elution program time is 15 min, and the elution speed is 1 mL / min. The specific elution program is as follows: At 0 min, phase A is 98% and phase B is 2%; within 0 - 10.6 min, phase A gradually decreases to 58% and phase B gradually increases to 42%; within 10.60 - 10.61 min, phase A increases to 98% and phase B decreases to 2%; within 10.61 - 15 min, maintain this elution ratio, phase A is 98% and phase B is 2% until the elution ends. Draw a standard curve with the peak area of cyanidin-3-O-glucoside at a standard concentration at a detection wavelength of 520 nm, and calculate the encapsulation efficiency (%) of the sample.

[0028] Table 1 shows the phosphorus content of potato starch and its binding rate (%) with cyanidin-3-O-glucoside under different pH conditions during the phosphorylation process Table 1

[0029] As shown in Table 1, under the conditions of pH 6, 9, and 11, the phosphorus content of the phosphorylated starch increased significantly, and the binding rate with cyanidin-3-O-glucoside also increased significantly. Moreover, with the increase in phosphorus content, the binding rate generally showed an upward trend. At pH 11, the phosphorus content of the starch was the highest, and the binding rate with cyanidin-3-O-glucoside was also the highest, reaching 75.29%.

[0030] It can be seen that starch phosphorylation can strengthen the interaction between starch and polyphenols, promote their combination, and thus better protect polyphenols.

[0031] The above has detailed the present invention. For those skilled in the art, without departing from the purpose and scope of the present invention and without unnecessary experiments, the present invention can be implemented within a relatively wide range under equivalent parameters, concentrations, and conditions. Although specific embodiments of the present invention are given, it should be understood that the present invention can be further improved. In short, according to the principle of the present invention, this application intends to include any changes, uses, or improvements to the present invention, including changes made using conventional techniques known in the art that depart from the scope disclosed in this application.

Claims

1. A method for enhancing the interaction between starch and polyphenols, comprising the following steps: 1) Reacting natural starch with a phosphorylating agent to obtain phosphorylated starch; 2) Adding the phosphorylated starch into an aqueous solution, adding polyphenols to the obtained phosphorylated starch solution, and storing the obtained phosphorylated starch / polyphenol mixture at a low temperature.

2. The method according to claim 1, wherein In step 1), the natural starch is at least one of potato starch, yam starch, and cassava starch; The phosphorylating agent is any one or a mixture of sodium tripolyphosphate and sodium metaphosphate; The reaction uses anhydrous sodium sulfate as a catalyst; The mass ratio of the natural starch to the phosphorylating agent is: (5 - 50):1; The mass ratio of the natural starch to anhydrous sodium sulfate is: (15 - 25):

1.

3. The method according to claim 1, wherein In step 1), the pH of the reaction system is 6 - 11; The reaction time is 30 - 90 min; The reaction is carried out under stirring; After the reaction ends, it further includes the operation of drying the obtained reaction system at a low temperature until the water content is 15% - 20% and then carrying out a high-temperature reaction, wherein the temperature of the low-temperature drying is 30 - 50 °C; The temperature of the high-temperature reaction is 130 - 150 °C, and the time can be 1.5 - 3 h.

4. The method according to claim 1, wherein After the high-temperature reaction ends, it further includes: after the sample is cooled, adding distilled water, mixing evenly, centrifuging the obtained suspension, removing the supernatant, adding distilled water to the solid residue and mixing evenly, adjusting the pH value to 6 - 7, repeating the above operations multiple times, and drying to obtain phosphorylated starch; wherein the temperature of the drying is 30 - 50 °C and the time is 15 - 25 h.

5. The method according to claim 1, wherein In step 2), the aqueous solution is pure water or at least one of hydrochloric acid aqueous solution, citric acid aqueous solution, and phosphate solution, and the pH of the aqueous solution is 3 - 7; The mass ratio of the aqueous solution to the phosphorylated starch is: 1:(0.001 - 0.1); The type of the polyphenols is polyphenol monomers, selected from: ferulic acid, epigallocatechin gallate, (+)-catechin, cyanidin-3-O-glucoside, or a mixture or crude extract of polyphenols; The polyphenol concentration in the obtained system is 10 -6 -10 -1 g / L; The temperature of the low-temperature storage is 0 - 10 °C.

6. The method according to claim 1, characterized in that, The method further includes the operation of centrifuging and separating the system after low-temperature storage to collect the phosphorylated starch-polyphenol liquid complex; The above operation can further include the operation of freeze-drying the obtained phosphorylated starch-polyphenol liquid complex to obtain a complex solid.

7. The phosphorylated starch-polyphenol liquid complex or complex solid obtained in claim 6.

8. Use of the phosphorylated starch-polyphenol liquid complex or complex solid according to claim 7 in the field of food processing.

9. Use of the method according to any one of claims 1 - 6 in the processing and storage of polyphenol-rich foods.

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