Hydrophobic modified starch Pickering emulsion embedded quercetin and application thereof in meat protein gel

Abstract

The invention discloses hydrophobic modified starch Pickering emulsion embedded quercetin and application of the hydrophobic modified starch Pickering emulsion embedded quercetin in meat protein gel. The hydrophobic modified starch Pickering emulsion embedded quercetin comprises the following steps: S1, preparing octenyl succinic anhydride (OSA) hydrophobic modified starch; s2, dissolving quercetin in soybean oil to form an oil phase, dispersing the OSA hydrophobic modified starch in water to form an OSA hydrophobic modified starch aqueous dispersion as a water phase, mixing the oil phase with the water phase, and performing high-speed shearing emulsification treatment to obtain hydrophobic modified starch Pickering emulsion embedded quercetin; s3, uniformly mixing the hydrophobic modified starch Pickering emulsion embedded quercetin with the myofibrillar protein diluent, cooking in a water bath, and cooling to obtain the emulsion type myofibrillar protein gel. According to the invention, not only is the performance of the meat protein gel improved, but also the bioavailability of the quercetin is improved.

Description

Technical Field

[0001] The invention belongs to the technical field of food processing, and particularly relates to a hydrophobically modified starch Pickering emulsion embedding quercetin and application of the emulsion in meat protein gel. Background Art

[0002] Starch is a widely available, renewable, inexpensive, safe, and non-toxic high-molecular-weight polysaccharide polymer that has been widely used in various fields. However, natural starch has drawbacks such as poor processing properties and unstable finished product quality, which limit its widespread application in the food industry.

[0003] As the demand for healthy diet grows, although bioactive substances such as quercetin have antioxidant and anti-inflammatory effects and are widely used in many fields, their poor water solubility, low chemical stability and weak bioavailability limit their application in food.

[0004] Therefore, modifying starch through physical, chemical, biological and other technical means becomes the key to solving the problem. Summary of the Invention

[0005] Objective: To overcome the deficiencies in the prior art, the present invention provides a hydrophobically modified starch Pickering emulsion for encapsulating quercetin and its application in meat protein gel, thereby improving the performance of the meat protein gel, delaying the release of quercetin, and increasing its bioavailability.

[0006] Octenyl succinate starch (OSA starch) is obtained by introducing hydrophobic groups into starch through esterification reaction, which gives it good emulsifying properties. It has been widely used in various food systems and emulsion preparations, effectively improving product quality and stability.

[0007] The application of OSA hydrophobically modified starch Pickering emulsion to encapsulate quercetin in meat protein gel can improve the performance of meat protein gel, delay the release of quercetin, and increase its bioavailability, providing a certain theoretical basis for the production of new emulsified meat products that can ensure nutritional value and have antioxidant effects.

[0008] Technical solution: To solve the above technical problems, the technical solution adopted by the present invention is: In a first aspect, a method for preparing an emulsion-type myofibrillar protein gel based on quercetin embedded in a hydrophobically modified starch Pickering emulsion is provided, comprising the following steps: S1. Preparation of octenyl succinic anhydride (OSA) hydrophobically modified starch; S2. Quercetin was dissolved in soybean oil to form an oil phase, OSA hydrophobically modified starch was dispersed in water to form an OSA hydrophobically modified starch aqueous dispersion as the aqueous phase, the oil phase and the aqueous phase were mixed, and a hydrophobically modified starch Pickering emulsion encapsulating quercetin was prepared by high-speed shear emulsification treatment; S3. After the hydrophobically modified starch Pickering emulsion encapsulating quercetin is mixed evenly with the myofibrillar protein dilution, the mixture is steamed in a water bath and cooled to obtain an emulsion-type myofibrillar protein gel.

[0009] In some embodiments, S1 prepares octenyl succinic anhydride (OSA) hydrophobically modified starch, specifically comprising: S11. Dispersing starch in water to prepare a starch dispersion, adjusting the pH to 8.0-9.0 (preferably 8.5); S12. The starch dispersion is placed in a water bath at 30-40°C (preferably 35°C), and octenylsuccinic anhydride diluted 5-fold with anhydrous ethanol is added for reaction. After the reaction is complete, the pH is adjusted to 6.0-7.0 (preferably 6.5) to terminate the reaction; S13. The mixture is washed with water and anhydrous ethanol, dried at 35-45° C. (preferably 40° C.), and sieved to obtain OSA hydrophobically modified starch.

[0010] In some embodiments, in S11, the starch is selected from at least one of rice starch RS and waxy corn starch CS; In S11, the starch concentration in the starch dispersion is 20-40 wt%, preferably 30 wt%.

[0011] In some embodiments, in S12, the amount of octenylsuccinic anhydride added is 1-5 wt % of the mass of starch in the starch dispersion, preferably 3 wt %.

[0012] In some embodiments, S2 satisfies at least one of the following: In S2, the concentration of quercetin in the oil phase was 2 mg / mL; In S2, the content of OSA hydrophobically modified starch in the OSA hydrophobically modified starch aqueous dispersion is 1 wt %; In S2, during the preparation of hydrophobically modified starch Pickering emulsion for quercetin encapsulation, the mass ratio of oil phase to water phase was 1:4.

[0013] In some embodiments, S3 satisfies at least one of the following: In S3, the concentration of the myofibrillar protein dilution is 2-6 wt%, preferably 4 wt%; In S3, the myofibrillar protein dilution solution is prepared by diluting myofibrillar protein with a buffer solution to obtain the myofibrillar protein dilution solution; wherein the buffer solution comprises 15 mmol / L piperazine-1,4-diethanesulfonic acid (PIPES) (pH 6.25) and 0.6 mol / L NaCl.

[0014] In some embodiments, S3 satisfies at least one of the following: In S3, the mass ratio of quercetin embedded in the hydrophobically modified starch Pickering emulsion and the myofibrillar protein dilution was 1:1; In S3, the water bath cooking is performed by heating in a water bath at 60 to 80° C. for 10 to 30 min, preferably in a water bath at 70° C. for 20 min.

[0015] In some embodiments, the method for obtaining myofibrillar protein comprises: Fresh pork tenderloin is removed of fat and connective tissue and then cut into small pieces; the minced pork tenderloin is mixed with phosphate buffer, homogenized, filtered, and centrifuged to obtain a precipitate; wherein the phosphate buffer comprises 0.1 M NaCl, 10 mM Na2HPO4·12H2O, 2 mM MgCl2, 1 mM EGTA, pH 7.0; 0.1 mol / L NaCl solution was added to the obtained precipitate, and the mixture was homogenized again, filtered, and centrifuged to obtain a precipitate. Finally, the pH was adjusted to 6.25, and the precipitate was obtained by centrifugation to obtain myofibrillar protein.

[0016] In a second aspect, an emulsion-type myofibrillar protein gel based on hydrophobically modified starch Pickering emulsion embedding quercetin is provided, which is prepared by the above method.

[0017] In a third aspect, the invention provides the use of the emulsion-type myofibrillar protein gel based on hydrophobically modified starch Pickering emulsion embedding quercetin in improving the performance of meat protein gel and the bioavailability of quercetin.

[0018] Furthermore, experiments have shown that the hydrophobically modified starch Pickering emulsion prepared by the method of the present invention, which encapsulates quercetin, improves the gel strength and water holding capacity of the meat protein gel and improves the bioavailability of quercetin.

[0019] Compared with the prior art, the beneficial effects of the present invention are as follows: the present invention provides a method for encapsulating quercetin in a hydrophobically modified starch emulsion and its application in meat protein gel. By encapsulating quercetin in the emulsion, the encapsulation rate of quercetin is significantly improved, and the antioxidant properties of the emulsion are improved. The addition of OSA hydrophobically modified starch Pickering emulsion improves the gel strength and water retention of the meat protein gel. The results of in vitro simulated digestion show that the bioavailability of quercetin is improved. This method provides a certain theoretical basis for the partial replacement of animal fat and improvement of the antioxidant properties of the product by encapsulating quercetin in OSA hydrophobically modified starch emulsion, and has important guiding significance for the development of low-fat functional emulsified meat products. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the specific implementation of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for the specific implementation or the description of the prior art.

[0021] Figure 1 This is a flow chart of the application of the hydrophobically modified starch emulsion to embed quercetin in meat protein gel in the present invention; Figure 2 is the Fourier infrared spectrum of the hydrophobically modified starch of the present invention; Figure 3 Schematic diagram of the gel strength (A) and water holding capacity (B) of the hydrophobically modified starch emulsion gel of the present invention; Figure 4 Schematic diagram of the free fatty acid release rate in the digestive fluid of the hydrophobically modified starch emulsion gel of the present invention; Figure 5 Schematic diagram of particle size (A) and potential (B) of the hydrophobically modified starch emulsion gel digestion solution at each digestion stage in the present invention: Figure 6 Schematic diagram of the bioavailability of quercetin in the digestive fluid of the hydrophobically modified starch emulsion gel of the present invention.

[0022] Figure 2 Middle: OSA-CS represents OSA-modified waxy corn starch, OSA-RS represents OSA-modified rice starch; NRS represents native rice starch, and NCS represents native waxy corn starch; Figures 3 to 6 Chinese: NREG and NCEG represent natural rice starch and waxy corn starch emulsion gels; OSA-REG and OSA-CEG represent OSA-modified rice starch and waxy corn starch emulsion gels; OSA-RQEG and OSA-CQEG represent OSA-modified rice starch and waxy corn starch quercetin emulsion gels; NRQEG and NCQEG represent natural rice starch and waxy corn starch quercetin emulsion gels, respectively. DETAILED DESCRIPTION

[0023] The technical solutions of the present invention will be described clearly and completely below in conjunction with the accompanying drawings to facilitate a better understanding of the present invention. In addition, the technical features involved in the different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0024] The methods used in the following examples are conventional methods unless otherwise specified. The materials, instruments and reagents used are conventional materials, instruments and reagents in the art, and can be obtained commercially by those skilled in the art unless otherwise specified. In this application, % represents mass percentage unless otherwise specified.

[0025] like Figure 1 As shown, the present invention provides a method for using a hydrophobically modified starch emulsion to embed quercetin in a meat protein gel, comprising the following steps: Example 1: Preparation of hydrophobically modified starch Two starches (rice starch: RS, waxy corn starch: CS) were prepared into 30% solutions and the pH was adjusted to 8.5. OSA (1%, 2%, and 3%, based on starch mass) diluted 5 times with anhydrous ethanol was added in a constant temperature magnetic stirring water bath at 35°C for 5 h. The reaction was terminated by adjusting the pH to 6.5. The starch was washed twice with distilled water and twice with anhydrous ethanol, dried at 40°C for 24 h, and passed through a 100-mesh sieve to obtain OSA hydrophobically modified starch.

[0026] The degree of substitution of OSA hydrophobically modified starch was determined by titration, as shown in Table 1.

[0027] Table 1 Degree of substitution of hydrophobically modified starch

[0028] Note: Different lowercase letters (af) indicate significant differences among different treatment groups ( P <0.05).

[0029] As shown in Table 1, the degree of substitution increases with increasing OSA concentration. When the OSA concentration is 3%, the degrees of substitution for both starches reach their maximum, reaching 1.86% ± 0.03 and 1.75% ± 0.01, respectively. This result suggests that increasing the OSA concentration allows more OSA groups to be introduced into the starch, increasing the degree of substitution.

[0030] Example 2: Preparation of hydrophobically modified starch emulsion embedded quercetin Quercetin was dissolved in soybean oil (2 mg / mL) to form an oil phase, and 1% OSA hydrophobically modified starch aqueous dispersion was used as the aqueous phase. The oil phase and the aqueous phase were mixed at a mass ratio of 1:4 and subjected to high-speed shear treatment to prepare a Pickering emulsion encapsulating quercetin. The results of quercetin encapsulation efficiency in the emulsions prepared by hydrophobically modified starch with different OSA concentrations are shown in Table 2.

[0031] Table 2 Quercetin encapsulation efficiency of natural starch and hydrophobically modified starch emulsions with different OSA concentrations

[0032] Note: Different lowercase letters (ag) indicate significant differences among different treatment groups ( P <0.05).

[0033] The data in Table 2 show that compared to native starch, the OSA hydrophobically modified starch emulsion significantly improved the quercetin encapsulation efficiency, reaching 70.19±0.64% and 80.17±0.73% for the two OSA hydrophobically modified starch emulsions, respectively. This is related to the emulsifying properties of the OSA hydrophobically modified starch emulsion. The OSA hydrophobically modified starch forms a stable Pickering emulsion at the oil-water interface through amphiphilic adsorption, effectively preventing the free precipitation and exposure and decomposition of the bioactive substance quercetin in the oil phase, thereby improving the quercetin encapsulation efficiency.

[0034] Example 3: Application of OSA hydrophobically modified starch emulsion to embed quercetin in meat protein gel Fresh pork tenderloin was removed of fat and connective tissue and then cut into small pieces. The minced pork tenderloin was mixed with phosphate buffer (0.1 M NaCl, 10 mM Na2HPO4·12H2O, 2 mM MgCl2, 1 mM EGTA, pH 7.0), homogenized, filtered, and centrifuged to obtain a precipitate. Add 0.1 mol / L NaCl solution to the obtained precipitate, homogenize again, filter, and centrifuge to obtain a precipitate. Finally, adjust the pH to 6.25 and centrifuge to obtain a precipitate. This precipitate is the desired myofibrillar protein.

[0035] The OSA hydrophobically modified starch emulsion-embedded quercetin emulsion and myofibrillar protein dilution were mixed at a mass ratio of 1:1 and heated in a water bath at 70°C for 20 min to obtain an emulsion-type myofibrillar protein gel. Simulated digestive fluid was added to the gel to study the effect of quercetin encapsulated in hydrophobically modified starch emulsion on the digestibility of meat protein gel.

[0036] Performance Analysis: (1) Characterization of hydrophobically modified starch structure by Fourier transform infrared spectroscopy Fourier transform infrared spectroscopy plays an important role in identifying compounds and characterizing molecular structures, and is used to verify the occurrence of esterification reactions. Figure 2 As shown in the figure, after esterification modification, the long hydrophobic chain of OSA is introduced into the glucose unit of starch molecules, but the basic structure of starch does not change significantly. Therefore, the infrared spectra of OSA hydrophobically modified starch with different degrees of substitution are similar to those of natural starch. Compared with natural starch, OSA hydrophobically modified starch has a typical characteristic absorption peak of glucose unit, and OSA-RS and OSA-CS have a peak at 1570 cm -1 and 1726 cm -1 Two new characteristic peaks appeared at , which were mainly caused by the asymmetric stretching vibration of the carboxyl RCOO- group and the C=O stretching vibration, confirming the successful progress of the esterification reaction.

[0037] (2) Analysis of gel strength and water retention from Figure 3 As can be seen in Figure (A), the addition of OSA hydrophobically modified starch Pickering emulsion significantly improves gel strength compared to native starch emulsion gels. At an OSA concentration of 3%, the gel strengths of OSA-RQEG and OSA-CQEG were 1.94 (1.89) and 2.04 (2.04) times greater than those of the control. This is because the hydrophobically modified OSA starch particles swell during the gelation process and are integrated into the gel network, thereby enhancing the gel strength of the meat protein gel.

[0038] from Figure 3 As shown in Figure (B), the water-holding capacities of the gels formed after adding myofibrillar protein MP to the native starch emulsion were 25.05% and 27.06%, respectively. When the OSA hydrophobically modified starch emulsion was added to myofibrillar protein MP to prepare the gel, the water-holding capacity was significantly improved. This enhanced water-holding capacity is primarily attributed to the higher viscosity of the OSA hydrophobically modified starch Pickering emulsion, which likely hinders the mobility of water within the gel, thereby reducing water exudation. Furthermore, the OSA hydrophobically modified starch granules swell with water during gelatinization. These starch granules compete with myofibrillar protein MP for water absorption, resulting in greater water retention within the gel. Overall, the gel strength and water-holding capacity results indicate that the OSA hydrophobically modified starch Pickering emulsion can improve the gel properties of meat protein gels, with OSA-CS being more effective than OSA-RS.

[0039] (5) Analysis of digestive fluid particle size and potential The changes in particle size and potential during digestion are as follows Figure 4 As shown in the figure, due to the short oral digestion time, the particle size of the digestive fluid did not change significantly. After simulated gastric digestion, the particle size of all digestive fluids increased significantly, but the particle size change of the native starch emulsion gel digestive fluid was more obvious than that of the OSA-modified starch emulsion gel digestive fluid. This is mainly due to the lack of starch hydrolyzing enzymes in the simulated gastric digestive fluid. At the same time, the changes in pH and ionic strength weakened the electrostatic repulsion between the digestive fluids, resulting in an increase in particle size. After simulated small intestinal digestion, the particle size of the digestive fluid decreased sharply, with the particle size of the OSA-CEG digestive fluid being smaller than that of the OSA-REG digestive fluid. This is because most of the lipids in the digestive fluid are hydrolyzed by pancreatic lipase, leaving a small amount of undigested emulsion. At the same time, the complex mixture produced by lipid digestion (such as vesicles and micelles) further reduced the particle size of the digestive fluid.

[0040] During the oral digestion stage, the potential of all digestive fluids was negative, which may be due to the change in the charge of the digestive fluid caused by adsorbed or free negatively charged proteins. During the simulated gastric digestion process, the positive charge of H⁺ and mineral ions in the digestive fluid can neutralize the negatively charged succinic acid groups in the oil droplets stabilized by OSA-modified starch, thereby weakening the electrostatic repulsion and causing liquid aggregation. Therefore, the potential of all samples decreased significantly after simulated gastric digestion. After entering the simulated intestinal stage, the potential of all digestive fluids increased significantly, such as Figure 4 This is because the presence of various anionic substances in intestinal digestive fluid, such as bile salts, phospholipids, and free fatty acids, imparts a strong negative charge to the sample particles after passing through the small intestine. Furthermore, the higher pH environment in the intestine contributes to the digestive fluid exhibiting a more negative potential value.

[0041] (3) Analysis of free fatty acid release rate As the digestion process progressed, the release of free fatty acids in all samples gradually increased, e.g. Figure 4 、 Figure 5 As shown in the figure, free fatty acids are released rapidly during the initial digestion phase (0–30 min). The release rate increases slowly during the 30–60 min digestion phase. After 60 min, most of the lipids are hydrolyzed by pancreatic lipase, resulting in a more gradual release of free fatty acids. After digestion, the release of free fatty acids decreases in the following order: OSA-CEG (OSA-CQEG) > OSA-REG (OSA-RQEG) > NCEG (NCQEG) > NREG (NRQEG). This phenomenon is related to the smaller size of the OSA hydrophobically modified starch emulsion gel digests. Smaller emulsion droplets increase the contact area with lipase, thereby promoting free fatty acid release. Furthermore, throughout the simulated intestinal digestion process, the free fatty acid release rate of the native starch emulsion gel digests is lower. This may be because the larger emulsion droplets in the digests reduce the contact area with lipase, inhibiting lipase action and thus reducing free fatty acid release.

[0042] (6) Analysis of bioavailability The bioavailability of quercetin refers to the percentage of quercetin dissolved in the intestinal fluid in the form of micelles. Figure 6As shown, the bioavailability of quercetin in digestive fluid from OSA hydrophobically modified starch emulsion gels was significantly improved compared to that from native starch emulsion gels. The bioavailability of quercetin in OSA-CQEG (36.31%) was higher than that in OSA-RQEG (31.73%). This may be because meat protein gels prepared with OSA-CS emulsions are more resistant to the adverse gastric environment, reducing quercetin release during simulated gastric digestion. During simulated intestinal digestion, the emulsion droplet size in OSA-CQEG digestive fluid was smaller than that in OSA-RQEG digestive fluid, increasing the surface area exposed to lipase and promoting lipase digestion of the oil droplets, resulting in more complete quercetin release and improved bioavailability.

[0043] The above description is merely a preferred embodiment of the present invention and is not intended to limit the embodiments of the present invention. It should be understood by those skilled in the art that any modifications, equivalent substitutions, and improvements based on the present invention, without departing from the inventive concept of the present invention, fall within the scope of protection claimed in the present invention.

Claims

1. A method for preparing an emulsion-type myofibrillar protein gel based on quercetin embedded in a hydrophobically modified starch Pickering emulsion, characterized in that: The following steps are involved: S1. Preparation of octenyl succinic anhydride OSA hydrophobically modified starch; S2. Quercetin was dissolved in soybean oil to form an oil phase, OSA hydrophobically modified starch was dispersed in water to form an OSA hydrophobically modified starch aqueous dispersion as the aqueous phase, the oil phase and the aqueous phase were mixed, and a hydrophobically modified starch Pickering emulsion encapsulating quercetin was prepared by high-speed shear emulsification treatment; S3. After the hydrophobically modified starch Pickering emulsion encapsulating quercetin is mixed evenly with the myofibrillar protein dilution, the mixture is steamed in a water bath and cooled to obtain an emulsion-type myofibrillar protein gel.

2. The preparation method according to claim 1, characterized in that S1 specifically includes: S11. Disperse the starch in water to prepare a starch dispersion, and adjust the pH to 8.0-9.0; S12. Place the starch dispersion in a water bath at 30-40°C, add octenylsuccinic anhydride diluted 5-fold with anhydrous ethanol, and after completion of the reaction, adjust the pH to 6.0-7.0 to terminate the reaction; S13. The mixture was washed with water and anhydrous ethanol, dried at 35-45°C, and sieved to obtain OSA hydrophobically modified starch.

3. The preparation method according to claim 2, characterized in that In S11, the starch is selected from at least one of rice starch RS and waxy corn starch CS; And / or, in S11, the starch concentration in the starch dispersion is 20-40 wt %, preferably 30 wt %.

4. The preparation method according to claim 2, characterized in that In S12, the amount of octenylsuccinic anhydride added is 1 to 5 wt % of the mass of starch in the starch dispersion, preferably 3 wt %.

5. The emulsion-type myofibrillar protein gel according to claim 1, characterized in that: S2 satisfies at least one of the following: In S2, the concentration of quercetin in the oil phase was 2 mg / mL; In S2, the content of OSA hydrophobically modified starch in the OSA hydrophobically modified starch aqueous dispersion is 1 wt %; In S2, during the preparation of hydrophobically modified starch Pickering emulsion for quercetin encapsulation, the mass ratio of oil phase to water phase was 1:

4.

6. The preparation method according to claim 1, characterized in that S3 satisfies at least one of the following: In S3, the concentration of the myofibrillar protein dilution is 2-6 wt%, preferably 4 wt%; In S3, the myofibrillar protein dilution solution is prepared by diluting myofibrillar protein with a buffer solution to obtain the myofibrillar protein dilution solution; wherein the buffer solution comprises 15 mmol / L piperazine-1,4-diethanesulfonic acid (PIPES) and 0.6 mol / L NaCl.

7. The preparation method according to claim 1, characterized in that S3 satisfies at least one of the following: In S3, the mass ratio of quercetin embedded in the hydrophobically modified starch Pickering emulsion and the myofibrillar protein dilution was 1:1; In S3, the water bath cooking is performed by heating in a water bath at 60 to 80° C. for 10 to 30 min, preferably in a water bath at 70° C. for 20 min.

8. The preparation method according to claim 1 or 6, characterized in that The method for obtaining the myofibrillar protein comprises: Fresh pork tenderloin is removed of fat and connective tissue and then cut into small pieces; the minced pork tenderloin is mixed with phosphate buffer, homogenized, filtered, and centrifuged to obtain a precipitate; wherein the phosphate buffer comprises 0.1 M NaCl, 10 mM Na2HPO4·12H2O, 2 mM MgCl2, 1 mM EGTA, pH 7.0; 0.1 mol / L NaCl solution was added to the obtained precipitate, and the mixture was homogenized again, filtered, and centrifuged to obtain a precipitate. Finally, the pH was adjusted to 6.25, and the precipitate was obtained by centrifugation to obtain myofibrillar protein.

9. An emulsion-type myofibrillar protein gel based on hydrophobically modified starch Pickering emulsion embedding quercetin, characterized in that: The method is prepared by any one of claims 1 to 8.

10. Use of the emulsion-type myofibrillar protein gel based on hydrophobically modified starch Pickering emulsion embedding quercetin according to claim 9 in improving the performance of meat protein gel and the bioavailability of quercetin.

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