Preparation method of rice protein peptide-sodium alginate composite hydrogel

Abstract

The invention discloses a preparation method of rice protein peptide-sodium alginate composite hydrogel, which is characterized in that rice protein peptide obtained by treatment under different enzymolysis conditions is mixed with sodium alginate, nano calcium carbonate and glucolactone for reaction, and gel is formed through cross-linking action. According to the method, the preparation method of the peptide gel is successfully improved, and the gel prepared by compounding the rice protein peptide obtained by treatment under different enzymolysis conditions with sodium alginate has the advantages of simple preparation method process, moderate gel speed, easiness in control, strong gel water binding capacity, relatively strong gel strength and thermal irreversibility.

Description

Technical Field

[0001] The invention belongs to the technical field of edible processing, and particularly relates to a method for preparing a rice protein peptide-sodium alginate composite hydrogel. Background Art

[0002] In recent years, protein peptide gels have had a profound impact on wound repair, cosmetics, health food development, and improving food texture and stability. However, some existing protein peptide gels have limited solubility, gelation, and biocompatibility under external conditions such as pH, temperature, and anti-nutritional factors. Therefore, the development of a new, stable composite peptide gel has certain significance for the development of new foods and daily chemical products.

[0003] The method that currently adopts mostly has polypeptide and compound to form peptide gel under catalyst action, and protein peptide self-assembly forms peptide gel and protein peptide and gelatin, xanthan gum mix and make composite gel.But the above-mentioned preparation method exists the shortcomings such as long preparation time, cumbersome process, uncommon material, material can not adapt to fully and heat reversible.Therefore, the present invention adopts the mode that rice protein peptide, sodium alginate nano calcium carbonate and gluconolactone obtained under different enzymolysis conditions mix, circumvents the problem that rice protein peptide can not self-assemble to form gel and other common composite gel heat reversible, and has higher water holding capacity and gel strength to a certain extent. Summary of the Invention

[0004] Purpose of the Invention: To address the problems of the prior art, the present invention provides a simple, rapid, and room-temperature method for preparing rice protein peptide gels. Rice protein peptides obtained under different enzymatic hydrolysis conditions are cross-linked with sodium alginate, nano-calcium carbonate, and gluconolactone to form a thermally irreversible gel in a short period of time. The gel exhibits advantages such as nontoxicity, biocompatibility, structural stability, low cost, and strong hydrophilicity. This method effectively addresses the problem of decreased functional activity of rice peptides due to insufficient stability, creating an ideal delivery system for rice peptides.

[0005] Technical solution: The method for preparing a rice protein peptide-sodium alginate composite hydrogel of the present invention comprises the following steps:

[0006] (1) Rice protein powder is dissolved in water ultrasound, after homogenization, rice protein solution is added enzyme constant temperature stirring, hydrolyzed solution is heated, cooled centrifuged and supernatant is taken, and lyophilized to obtain freeze-dried protein hydrolysate;

[0007] (2) Sodium alginate is dissolved in water to adjust the pH, the nano calcium carbonate aqueous solution and the freeze-dried protein hydrolyzate obtained in step (2) are added to the sodium alginate solution and stirred, and the gluconolactone solution is added and stirred to obtain the product.

[0008] Wherein, in step (1), ultrasonication is performed for 10-15 min at 300-500 W, the temperature during ultrasonication is 23-27° C., and the concentration of the rice protein solution is 8-12% w / w.

[0009] Wherein, the enzyme in step (1) is any one of alkaline protease, trypsin or flavor enzyme.

[0010] Wherein, in step (1), the ratio of enzyme to rice protein is 10000-3000 U / g.

[0011] Wherein, the constant temperature stirring temperature in step (1) is 20-30° C., and the stirring condition is 150-200 r / min.

[0012] Wherein, in step (1), the mixture is heated at 95-100° C. for 10-15 minutes, cooled to below 10° C., centrifuged at a constant temperature of 10,000-12,000×g for 20-25 minutes, and freeze-dried for 36-48 hours.

[0013] Wherein, the concentration of the sodium alginate solution in step (2) is 12-15 g / L, and the pH is adjusted to 10.5-11.0.

[0014] The concentration of the nano-calcium carbonate solution in step (2) is 0.2-0.4 mg / mL, the mass ratio of the nano-calcium carbonate aqueous solution to the freeze-dried protein hydrolysate is 3-5:800, and the solution is dissolved in the sodium alginate solution prepared above and stirred at 550-650 rpm for 5-7 minutes.

[0015] Wherein, in step (2), the mass ratio of the freeze-dried protein hydrolysate to gluconolactone is 40:1-3, and the mixture is stirred at 350-450 rpm for 1-1.5 min.

[0016] Wherein, the pH value of the solution monitored in step (2) is 7-7.4.

[0017] The rice protein peptide-sodium alginate composite hydrogel is prepared by the composite hydrogel preparation method of the present invention.

[0018] Application of the rice protein peptide-sodium alginate composite hydrogel of the present invention in functional foods or daily chemical skin care products.

[0019] Furthermore, the functional food includes those that can be used for effective substance delivery, easy-to-swallow food development, etc., and the daily chemical skin care products include gel masks, eye masks, etc.

[0020] The method comprises the following steps: dissolving rice protein powder in deionized water as a solvent, dividing the obtained protein solution into 9 groups (10% w / w, 100 mL each), transferring each group of samples into a 250 mL beaker, placing the beaker in an ice-water bath to ensure that the temperature during ultrasound is 25±2° C., and then performing ultrasound treatment for 15 minutes at a power of 400 W. After sonication, the protein solution was removed and hydrolyzed in a constant-temperature magnetic stirring waterbath using: alkaline protease (CAS#9014-001-1, S10154-100g, 200U / mg, source leaf) at pH 8.5, 50°C; trypsin (CAS#9002-07-7, S10032-25g, 250U / mg, source leaf) at pH 8.0, 37°C; and flavor protease (CAS#9001-92-7, F768979, 100,000U / g, MacLean) at pH 7.0, 0°C. The reaction time was 4 hours, with continuous stirring (150 rpm). Enzyme activity was terminated by heat inactivation (100°C waterbath, 10 minutes). The hydrolyzed samples were immediately cooled to 4°C and centrifuged (10,000×g, 20 min, 4°C). The supernatant was collected and lyophilized for 48 h. The lyophilized samples were stored at -20°C for the next gel preparation step.

[0021] A sodium alginate solution (15 mg / mL, 15 mL) was prepared and the pH was adjusted to 11.0 with 0.5 M NaOH. Nano-calcium carbonate (0.2 mg / mL, 15 mL) and freeze-dried protein hydrolysate were then uniformly dispersed into the sodium alginate solution by magnetic stirring (600 rpm, 5 min). Finally, gluconolactone (GDL, 0.06 g) was added to the homogeneous mixture to initiate gelation, followed by stirring (400 rpm, 1.5 min) to ensure uniform acid distribution. The pH value of the solution was monitored during the gelation process, and after gelation was completed, the pH value dropped to 7.0-7.4. The blank group remained unchanged except that the hydrolysate was not added. A composite hydrogel was thus prepared.

[0022] Beneficial effects: Compared with the prior art, the present invention has the following significant advantages:

[0023] 1. The composite hydrogel prepared by the present invention has the advantages of high antioxidant activity, good elasticity and high water holding capacity. The gel prepared by using sodium alginate, nano-calcium carbonate and gluconolactone mixed protein peptide has the advantages of good stability, thermal irreversibility and low cost. The gel formed by the rice protein peptide composite sodium alginate under different enzymatic hydrolysis conditions has different effects on hardness, resilience, gel strength, breaking force and water holding capacity, which can provide different options for different application scenarios;

[0024] 2. The gel preparation method of the present invention has a simple process, is easy to control and operate, and can form a gel at room temperature, which can effectively improve production efficiency and economic benefits in the production process. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 The appearance morphology of peptide-free gels with different ratios of calcium carbonate and GDL;

[0026] Figure 2 The results of water holding capacity measurement of rice protein hydrolysate and sodium alginate composite gel under different enzymatic hydrolysis conditions are shown;

[0027] Figure 3 The rheological measurement results of rice protein hydrolysate and sodium alginate composite gel under different enzymatic hydrolysis conditions;

[0028] Figure 4 is the average particle size of rice protein hydrolysate under different enzymatic hydrolysis conditions;

[0029] Figure 5 The antioxidant activity of rice protein hydrolysates under different enzymatic hydrolysis conditions. DETAILED DESCRIPTION

[0030] The present invention will be further described below with reference to specific embodiments and accompanying drawings.

[0031] The experimental methods in the following examples are conventional methods unless otherwise specified. The experimental materials used in the following examples are purchased from conventional biochemical reagent companies unless otherwise specified.

[0032] Rice protein powder: Wuxi Jinnong Biotechnology Co., Ltd.

[0033] Alkaline protease (CAS#9014-001-1, S10154-100g, 200U / mg, source leaf)

[0034] Trypsin (CAS#9002-07-7, S10032-25g, 250U / mg, source leaf)

[0035] Flavor protease (CAS#9001-92-7, F768979, 100,000 U / g, MacLean)

[0036] Nano-calcium carbonate: MacLean Reagent Company, C886288, particle size: 50 nm.

[0037] Example 1

[0038] Preparation of rice protein peptide-sodium alginate composite hydrogel by hydrolysis with alkaline protease (E / S = 10000 U / g)

[0039] (1) Rice protein powder was dissolved in deionized water as solvent, and 100 ml of the obtained protein solution (10% w / w) was transferred to a 250 ml beaker and placed in an ice-water bath to ensure that the temperature during ultrasound was 25 ± 2 ° C. Then, the protein solution was ultrasonicated at a power of 400 W for 15 minutes. The protein solution after ultrasound was taken out and hydrolyzed in a constant temperature magnetic stirring water bath using alkaline protease with an enzyme / substrate (E / S) ratio of 10,000 U / g (pH 8.5, 50 ° C). The reaction time was 4 hours (30 ° C). Stirring was continued during the reaction (150 r / min). The enzyme activity was terminated by heating inactivation (100 ° C water bath, 10 minutes). The hydrolyzed sample was immediately cooled to 4 ° C, then centrifuged (10,000 × g, 20 min, 4 ° C) and the supernatant was collected. The sample was lyophilized for 48 hours to obtain a lyophilized protein hydrolyzate. The lyophilized sample was stored at -20 ° C for the next step of gel preparation.

[0040] (2) Sodium alginate was dissolved in deionized water (15 g / L, 15 mL system) and the pH of the sodium alginate solution was adjusted to 11.0 with 0.5 M NaOH solution;

[0041] (3) Nano-calcium carbonate aqueous solution (0.2 mg / mL, 15 mL) and the obtained freeze-dried protein hydrolysate (0.8 g) were uniformly dispersed into the solution obtained in step (1) by magnetic stirring (600 rpm, 5 min);

[0042] (4) Add 0.06 g of gluconolactone (GDL) to the solution obtained in step (2) and start stirring (400 rpm, 1.5 min) to ensure uniform distribution. Monitor the pH value of the solution during the gelation process. After the gelation is completed, the pH value drops to 7.0-7.4.

[0043] Example 2

[0044] Preparation of rice protein peptide-sodium alginate composite hydrogel by trypsin (E / S = 10000 U / g) hydrolysis

[0045] The method in reference example 1 was performed using trypsin, an enzyme / substrate (E / S) ratio of 10000 U / g (pH 8.0, 37°C) for hydrolysis, and other conditions being unchanged to prepare a mixed gel of rice protein hydrolysate and sodium alginate obtained by trypsin (E / S=10000 U / g) hydrolysis.

[0046] Example 3

[0047] Flavor protease (E / S=10000U / g) was hydrolyzed to prepare rice protein peptide-sodium alginate composite hydrogel according to the method in Reference Example 1. Flavor protease was used, and the enzyme / substrate (E / S) ratio was 10000U / g (pH 7.0, 0°C) for hydrolysis. Other conditions were unchanged to prepare a mixed gel of rice protein hydrolysate and sodium alginate obtained by the hydrolysis of flavor protease (E / S=10000U / g).

[0048] Example 4

[0049] Effects of different ratios of calcium carbonate and GDL (gluconolactone) on gel appearance

[0050] Referring to the method in Example 1, the sodium alginate concentration was 15 g / L, and four groups of calcium carbonate and GDL (gluconolactone) ratios were set: 0.2 mg / mL calcium carbonate + 0.06 g GDL; 0.3 mg / mL calcium carbonate + 0.04 g GDL; 0.3 mg / mL calcium carbonate + 0.03 g GDL; 0.1 mg / mL calcium carbonate + 0.06 g GDL. The preparation results are shown in FIG. Figure 1 As shown, from left to right, the ratio of calcium carbonate and GDL is: 0.2 mg / mL calcium carbonate + 0.06 g GDL; 0.3 mg / mL calcium carbonate + 0.04 g GDL; 0.3 mg / mL calcium carbonate + 0.03 g GDL; 0.1 mg / mL calcium carbonate + 0.06 g GDL. By comparison, it is found that the gel of 0.2 mg / mL calcium carbonate + 0.06 g GDL is moderately soft and hard, has a moderate solidification speed, and has a more beautiful and translucent color.

[0051] Example 5

[0052] Preparation of rice protein peptide-sodium alginate composite hydrogel by hydrolysis with alkaline protease (E / S = 3000 U / g)

[0053] The method in Reference Example 1 was performed using alkaline protease with an enzyme / substrate (E / S) ratio of 3000 U / g (pH 8.5, 50° C.). Other conditions remained unchanged to obtain a mixed gel of rice protein hydrolysate and sodium alginate obtained by hydrolysis with alkaline protease (E / S=3000 U / g).

[0054] Example 6

[0055] Preparation of rice protein peptide-sodium alginate composite hydrogel by trypsin (E / S = 3000 U / g) hydrolysis

[0056] The method in reference example 1 was performed using trypsin, an enzyme / substrate (E / S) ratio of 3000 U / g (pH 8.0, 37°C) for hydrolysis, and other conditions being unchanged to prepare a mixed gel of rice protein hydrolysate and sodium alginate obtained by trypsin (E / S=3000 U / g) hydrolysis.

[0057] Example 7

[0058] Preparation of rice protein peptide-sodium alginate composite hydrogel by hydrolysis with flavor protease (E / S=3000U / g)

[0059] With reference to the method in Example 1, hydrolysis was performed using flavor protease at an enzyme / substrate (E / S) ratio of 3000 U / g (pH 7.0, 0° C.), with other conditions remaining unchanged, to prepare a mixed gel of rice protein hydrolysate obtained by hydrolysis with flavor protease (E / S=3000 U / g) and sodium alginate.

[0060] Example 8

[0061] Textural properties of rice protein peptide-sodium alginate composite hydrogel

[0062] The calcium alginate gel prepared without adding freeze-dried protein hydrolysate in Example 1 was used as a control ⑦. The gel texture properties of Examples 1-3 (①②③) and Examples 4-6 (④⑤⑥) were compared: a TA.XTC-18 texture analyzer (BosinTec, Hangzhou, Zhejiang) with a gel probe (TA / 0.5) was used for texture analysis. The trigger point value was set to 5gf, the deformation was 50%, and the detection speed was 5mm / s. The brittleness, resilience, gel strength, and breaking force of the gel were tested. All measurements were repeated three times. The texture properties of the rice protein hydrolysate and sodium alginate composite gel under different enzymatic hydrolysis conditions are shown in Table 1.

[0063] Analysis of results: In terms of hardness, group ⑥ had the strongest hardness, group ① had the weakest hardness, and the hardness value was lower than that of group ⑦ (blank control group); in terms of resilience, groups ①③④ had stronger hardness, and the differences among the other groups were not significant; in terms of gel strength, groups ③⑥ were the strongest, followed by ②⑤, and ①④ were the weakest; in terms of breaking force, groups ③⑥ were the strongest, followed by ②⑤, and ①④ were the weakest.

[0064] Table 1. Texture properties of rice protein peptide-sodium alginate composite hydrogels under different enzymatic hydrolysis conditions

[0065]

[0066] Example 9

[0067] Water retention of rice protein peptide-sodium alginate composite hydrogel

[0068] The calcium alginate gel prepared in Example 1 without the addition of freeze-dried protein hydrolysate was used as a control (7). 10 g of each of the gels prepared in Examples 1-3 (①, ②, and ③) and Examples 4-6 (④, ⑤, and ⑥) were placed in a centrifuge tube and centrifuged at 10,000 rpm for 20 minutes. After centrifugation, the water in the tube was poured out and the surface water of the sample was absorbed with filter paper. This test was repeated three times. The water holding capacity of the gel was calculated according to the following formula: WHC (%) = m2 / m1 × 100, where m1 represents the mass of the gel before centrifugation; m2 represents the mass of the gel after centrifugation.

[0069] The results are as follows Figure 2 As shown, the water-holding capacity of calcium alginate gel reflects the structural integrity of its three-dimensional network, which captures water molecules. It shows a concentration-dependent improvement with increasing enzyme-to-substrate (E / S) ratio. At the highest E / S ratio (10,000 U / g), the WHC values ​​of alkaline protease, trypsin, and flavor protease reached 97.0%, 96.93%, and 97.2%, respectively, representing increases of 1.03%, 0.96%, and 1.23%, respectively, compared to the untreated value of 95.97%. Although the absolute differences between enzyme treatments were small, flavor enzyme showed a consistent advantage across the E / S gradient, paralleling the finer particle size distribution observed.

[0070] Example 10

[0071] Rheological properties of rice protein peptide-sodium alginate composite hydrogel

[0072] The gelation process of different composite gel samples was measured using a TA AR-3000 rheometer. The calcium alginate gel prepared in Example 1 without adding freeze-dried protein hydrolysate was used as a control ⑦. The other parts of the gel prepared in Examples 1-3 (①②③) and 4-6 (④⑤⑥) were respectively taken and GDL was added and stirred for 1.5 minutes, and then transferred to the rheometer. The gel structure formation was measured using a cone plate with a diameter of 40 mm under the conditions of 25°C, a constant strain of 1.0%, and a frequency of 1 Hz. The frequency test was carried out at a constant strain of 1.0% and a temperature of 25°C to measure the changes in elastic modulus (G′) and frequency during the gelation process. All measurements were repeated three times.

[0073] The results are as follows Figure 3As shown, all formulations of composite gels exhibited progressive G' enhancement, indicating continuous cross-linking and structural consolidation. Notably, the hydrogel containing the flavour enzyme hydrolysate (E / S = 10,000 U / g) achieved the highest terminal G', suggesting the formation of a tightly interconnected network via synergistic peptide-alginates interactions. In contrast, the lower enzyme loading (E / S = 3,000 U / g) resulted in weaker gels with delayed G' growth kinetics, possibly due to the lack of bioactive peptides effectively substrate-stiffened. Frequency sweep analysis confirmed the structural hierarchy, indicating superior mechanical stability (lower frequency dependence of G') in the system with high E / S ratio (10,000 U / g).

[0074] Example 11

[0075] Average particle size of rice protein hydrolysates

[0076] The protein lyophilised concentrations prepared in Examples 1-3 (1 2 3) and Examples 4-6 (4 5 6) were diluted to 15 mg / mL with 0.2 M phosphate buffer (pH 7.0). The particle size distribution of each sample was measured using dynamic light scattering (Zetasizer Nano, Malvern Instruments, Worcestershire, UK) and all experiments were repeated in triplicate.

[0077] Results are shown in Figure 6. Figure 4 The hydrodynamic diameter of the rice protein was significantly reduced during enzymatic hydrolysis following sonication, with distinct changes observed across the different treatments. The mean particle size of the unhydrolysed protein (RPI) was 785.0 ± 10.0 nm, while the hydrolysates produced at an E / S ratio of 10,000 U / g were significantly reduced: 382.1 ± 9.9 nm (alcalase), 466.8 ± 7.6 nm (trypsin) and 352.0 ± 4.3 nm (flavourzyme). The study suggests that hydrolysates produced by proteases with restricted substrate specificity (e.g. trypsin) have a coarser particle distribution due to incomplete breakdown of the protein network. In contrast, the exopeptidase activity and broad cleavage specificity of flavourzyme can have facilitated the production of low molecular weight peptides, thereby enhancing colloidal instability and minimising particle size.

[0078] Example 12

[0079] Antioxidant activity of rice protein hydrolysates

[0080] The proteins prepared in Examples 1-3 (①②③) and Examples 4-6 (④⑤⑥) were lyophilized with deionized water at a ratio of 1:25 (w / w), and ultrasonicated at 320W for 20 min to obtain extracts of each group. Trolox (water-soluble vitamin E) was then used as a control, and 60% ethanol and 0.25 mM DPPH solution were used to react in the dark for 30 min. After the reaction was completed, the mixture was centrifuged at 5000 rpm for 10 min, and the supernatant was removed and the absorbance at 510 nm was measured. The DPPH RSP was calculated as follows:

[0081]

[0082] Where: A0 is 4 mL DPPH solution + 4 mL 60% ethanol; A1 is 4 mL DPPH solution + 3 mL 60% ethanol + 1 mL extract; A2 is 4 mL DPPH solution + 3 mL 60% ethanol + 1 mL extract

[0083] The results are as follows Figure 5 As shown in the figure, the antioxidant activity of rice protein hydrolysates under different enzymatic treatments was significantly different. DPPH free radical scavenging ability is a key indicator for measuring antioxidant activity. Figure 5 Results showed significant differences in the DPPH radical scavenging abilities of different enzymatic hydrolysates. At an E / S ratio of 3000 U / g, the flavorase-treated hydrolysate exhibited superior antioxidant activity, reaching 69.24%, 2.2-fold and 3.2-fold higher than those of alkaline protease (31.48%) and trypsin (21.77%), respectively. This hierarchy persisted at all E / S ratios, with flavorase achieving the highest activity (82.1%) at an E / S ratio of 10,000 U / g. The exceptional antioxidant capacity of flavorase hydrolysates may be attributed to their dual proteolytic properties: exopeptidase-driven peptide release: sequential cleavage of terminal residues yields short-chain peptides (<3 kDa) enriched in exposed aromatic (Tyr, Trp) and sulfur-containing (Cys, Met) amino acids, which exhibit enhanced free radical quenching via electron transfer pathways.

[0084] In summary, flavor protease hydrolysate has the best antioxidant activity, followed by alkaline protease hydrolysate, both of which are better than trypsin, but the overall effect is relatively excellent.

Claims

1. A method for preparing a rice protein peptide-sodium alginate composite hydrogel, characterized in that, The following steps are involved: (1) Rice protein powder is dissolved in water ultrasound, and the rice protein solution after homogenization is added with enzyme constant temperature stirring, the solution is heated after hydrolysis, and the supernatant is taken by cooling centrifugation, and lyophilized to obtain freeze-dried protein hydrolysate; (2) Sodium alginate is dissolved in water to adjust the pH, the nano calcium carbonate aqueous solution and the freeze-dried protein hydrolyzate obtained in step (2) are added to the sodium alginate solution and stirred, and the gluconolactone solution is added and stirred to obtain the product.

2. The method for preparing the composite hydrogel according to claim 1, wherein: In step (1), ultrasonic wave is applied for 10-15 min at 300-500 W, the temperature during ultrasonic wave is 23-27° C., and the concentration of rice protein solution is 8-12% w / w.

3. The method for preparing the composite hydrogel according to claim 1, wherein: The enzyme in step (1) is any one of alkaline protease, trypsin or flavor enzyme, and the ratio of the enzyme to rice protein in step (1) is 10000-3000 U / g.

4. The method for preparing the composite hydrogel according to claim 1, wherein In step (1), the constant temperature stirring temperature is 20-30°C, and the stirring condition is 150-200 r / min; the heating is heating at 95-100°C for 10-15 minutes, cooling to below 10°C, centrifuging at 10,000-12000×g for 20-25 minutes, taking the supernatant, and freeze-drying for 36-48 hours.

5. The method for preparing the composite hydrogel according to claim 1, wherein: In step (2), the concentration of the sodium alginate solution is 12-15 g / L, and the pH is adjusted to 10.5-11.

0.

6. The method for preparing the composite hydrogel according to claim 1, wherein: In step (2), the concentration of the nano-calcium carbonate solution is 0.2-0.4 mg / mL, the mass ratio of the nano-calcium carbonate aqueous solution to the freeze-dried protein hydrolysate is 3-5:800, and the solution is dissolved in the sodium alginate solution prepared above and stirred at 550-650 rpm for 5-7 minutes.

7. The method for preparing the composite hydrogel according to claim 1, wherein: In step (2), the mass ratio of the freeze-dried protein hydrolysate to gluconolactone is 40:1-3, and the mixture is stirred at 350-450 rpm for 1-1.5 min.

8. The method for preparing the composite hydrogel according to claim 1, wherein: The gluconolactone solution in step (2) is stirred, and the pH value of the resulting solution is 7-7.

4.

9. A rice protein peptide-sodium alginate composite hydrogel prepared by the method for preparing the composite hydrogel according to claim 1.

10. Use of the rice protein peptide-sodium alginate composite hydrogel according to claim 9 in functional foods or daily chemical skin care products.

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