Preparation method and application of premna microphylla polysaccharide-whey protein isolate composite gel

Abstract

The invention discloses premna pubescens polysaccharide-whey protein isolate composite gel as well as a preparation method and application of the premna pubescens polysaccharide-whey protein isolate composite gel. The method comprises the following steps: carrying out tartaric acid-assisted extraction and alcohol precipitation purification to obtain premna microphylla polysaccharide; respectively preparing 2.0%-5.0% by mass of stock solution and 25% by mass of stock solution with whey protein isolate; the preparation method comprises the following steps: mixing the raw materials according to a volume ratio of 1: 1, adjusting the pH value to 7.0, heating in a water bath at 95 DEG C for 30 minutes to induce gelation, and cooling. The water binding capacity of the obtained composite gel reaches 78.95%-80.26%, the hardness ranges from 16.67 N to 21.07 N, the elasticity ranges from 0.59% to 0.81%, the thermal decomposition temperature is stabilized to be 198 DEG C or above, and the rheological behavior shows the typical shear thinning characteristic, and the tan delta value ranges from 0.3 to 0.9. When the gel is applied to yoghourt, the whey precipitation rate can be reduced by 68%, the toughness can be improved by 45% when the gel is applied to jelly, and no obvious bleeding or deformation is caused after the gel is stored at 25 DEG C for one month. The raw materials are natural, the process is simple, the reproducibility is good, and a new way is provided for developing high-performance food colloid materials for cleaning labels.

Description

Technical Field

[0001] This invention belongs to the field of food gel materials technology, specifically, it relates to a method for preparing and applying a polysaccharide-whey protein isolate composite gel from *Clerodendrum trichotomum*. Background Technology

[0002] Whey protein isolate (WPI) is a high-quality natural food protein with a protein content of over 90%, and it is widely used in the food industry. However, single whey protein isolate gels suffer from drawbacks such as insufficient stability and limited functional properties, which restricts their application in high-end foods.

[0003] *Premna puberula* Pamb., a perennial erect shrub belonging to the genus *Premna* in the family Verbenaceae, is naturally distributed in Guizhou, Yunnan, and Sichuan provinces in southwestern my country, mostly in the wild. Its leaves are rich in pectin, protein, minerals, and active ingredients such as flavonoids and polyphenols, giving it high medicinal and edible value. However, due to the distinctive odor of its leaves, its edibility and processing adaptability are significantly limited, resulting in its long-term low level of development and utilization. Currently, it is only found in some remote areas of Guizhou and Yunnan for making the traditional food "Fairy Tofu," but the process is rudimentary and the form is limited. The large amount of wild and cultivated resources has not been effectively utilized, resulting in a significant waste of this natural functional ingredient.

[0004] Premna puberula leaves polysaccharides (PLP) are mainly extracted from vegetative organs such as leaves and stems, and are important functional components of Premna puberula. This polysaccharide is readily soluble in water but insoluble in organic solvents such as ethanol and acetone. Its aqueous solution is viscous, odorless, and exhibits excellent water solubility, biocompatibility, and chemical stability. It also displays various biological activities, including antioxidant, anti-inflammatory, and immunomodulatory effects, showing potential as a functional food matrix. However, its gelling properties have significant limitations: a single polysaccharide system cannot spontaneously form a structurally complete and mechanically stable three-dimensional network gel; its viscoelasticity, water-holding capacity, and structural integrity are all unsatisfactory, limiting its application as a gel matrix in food texture improvement. Current research focuses primarily on extraction process optimization and pharmaceutical activity evaluation; there is a lack of systematic exploration into its gelling behavior and food processing suitability, and no reports on its compounding with soy protein isolate through specific processes to construct high-performance composite gels with pH-responsive regulation capabilities. Therefore, its functional value has not been effectively realized.

[0005] In view of this, existing polysaccharide-protein composite gels suffer from problems such as insufficient optimization of the formulation, complex preparation processes, and the need to improve gel stability and water retention. Therefore, developing a polysaccharide-whey protein isolate composite gel from *Clerodendrum trichotomum* with a simple process and excellent performance is of great significance for expanding the application value of *Clerodendrum trichotomum* resources and promoting the modernization of traditional food production. Summary of the Invention

[0006] The purpose of this invention is to provide a method for preparing a polysaccharide-whey protein isolate composite gel from *Bromhidrosis pilosula*, which solves the problems of poor stability and limited function of single whey protein isolate gel, while achieving efficient utilization of *Bromhidrosis pilosula* resources.

[0007] Another object of the present invention is to provide the application of the composite gel in food.

[0008] This invention is achieved using the following technical solution: The preparation method of the polysaccharide-whey protein isolate composite gel from *Clerodendrum trichotomum* is carried out according to the following steps: (1) Extraction of polysaccharides from *Clerodendrum trichotomum*: Fresh leaves of *Clerodendrum trichotomum* are dried, crushed, and passed through a 50-100 mesh sieve to obtain *Clerodendrum trichotomum* powder. The powder is mixed with ultrapure water at a mass ratio of 1:10-50, and the pH is adjusted to 1-5 with tartaric acid. The mixture is extracted in a water bath at 75-105℃ for 0.5-4h, with stirring every 10min. After filtration, the filtrate is concentrated to 1 / 5-1 volume. 0.5-4.5 times the volume of 95% ethanol is added to the filtrate. The mixture is allowed to stand at 0-10℃ for 0.1-2.5h, and then centrifuged at 2500-7000r / min for 1-10min. The collected precipitate is dried at 44-78℃ for 1-10h to obtain *Clerodendrum trichotomum* polysaccharide extract for later use. (2) Preparation of polysaccharide stock solution of *Clerodendrum trichotomum*: Dissolve the polysaccharide extract of *Clerodendrum trichotomum* in ultrapure water to prepare polysaccharide solutions with mass fractions of 2.0%, 3%, 4%, and 5.0%, respectively. Place the solutions in a magnetic stirring environment at 10-45℃ and 300-650 r / min for 0.5-2 h, and then place them at 0-6℃ overnight to obtain polysaccharide stock solutions of 2.0%, 3%, 4%, and 5.0%d for later use. (3) Preparation of whey protein isolate solution: Dissolve whey protein isolate in ultrapure water to prepare a whey protein isolate solution with a mass fraction of 25%. Place it in a magnetic stirring environment at a temperature of 10-45℃ and a speed of 300-650r / min for 0.5-2h, and then place it at 0-6℃ overnight to dissolve the protein completely. The whey protein isolate solution is then ready for use. (4) Preparation of the mixed solution of *Clerodendrum tigrinum* polysaccharide and whey protein isolate: Take the 2.0%, 3%, 4%, and 5.0%d *Clerodendrum tigrinum* polysaccharide stock solutions from step (2) and the whey protein isolate solution from step (3) at a volume ratio of 1:0.1-3. Place them in a magnetic stirring system at a temperature of 10-45℃ and a speed of 100-550r / min for 10-55min until uniform. Adjust the pH to 4.0-10.0 to obtain mixed solutions of *Clerodendrum tigrinum* polysaccharide and whey protein isolate with polysaccharide concentrations of 1.0%, 1.5%, 2.0%, and 2.5%, respectively, for later use. (5) Thermal gelation: The 1.0%, 1.5%, 2.0% and 2.5% polysaccharide-whey protein isolate mixtures from step (4) were placed in a water bath at 70-120℃ and heated for 5-55 minutes, then cooled to room temperature in an ice water bath, sealed and refrigerated at 0-10℃ overnight to obtain polysaccharide-whey protein isolate composite gels with polysaccharide concentrations of 1.0%, 1.5%, 2.0% and 2.5%.

[0009] In step (1) above, the extraction of polysaccharides from *Clerodendrum thomsoniae* is as follows: Fresh leaves of *Clerodendrum thomsoniae* are dried, crushed, and passed through a 70-90 mesh sieve to obtain *Clerodendrum thomsoniae* powder. The powder is mixed with ultrapure water at a mass ratio of 1:20-40, and the pH is adjusted to 2-3 with tartaric acid. The mixture is extracted in a water bath at 86-98℃ for 1-3 hours, with stirring every 10 minutes. After filtration, the filtrate is concentrated to 1 / 4-1 / 2 volume. 1-3 times the volume of 95% ethanol is added to the filtrate, and the mixture is allowed to stand at 2-7℃ for 0.5-2 hours. The mixture is then centrifuged at 3500-5500 r / min for 3-6 minutes. The collected precipitate is dried at 55-70℃ for 3-9 hours to obtain the polysaccharide extract from *Clerodendrum thomsoniae*.

[0010] Specifically, in the aforementioned step (1), the extraction of polysaccharides from *Clerodendrum tigrinum* leaves is as follows: fresh *Clerodendrum tigrinum* leaves are dried, crushed, and passed through an 80-mesh sieve to obtain *Clerodendrum tigrinum* powder. The *Clerodendrum tigrinum* powder is mixed with ultrapure water at a mass ratio of 1:30, and the pH is adjusted to 2 with tartaric acid. The mixture is extracted in a 90°C water bath for 2 hours, with stirring every 10 minutes. After filtration, the filtrate is concentrated to 1 / 3 of its volume. Two times the volume of 95% ethanol is added to the filtrate, and the mixture is allowed to stand at 4°C for 1 hour. The mixture is then centrifuged at 4500 r / min for 5 minutes. The collected precipitate is dried at 60°C for 6-8 hours to obtain the *Clerodendrum tigrinum* polysaccharide extract.

[0011] In step (2) above, the polysaccharide extract of *Clerodendrum trichotomum* was dissolved in ultrapure water to prepare polysaccharide solutions with mass fractions of 2.0%, 3%, 4%, and 5.0%, respectively. After being placed at 25°C and magnetically stirred at 500 r / min for 1 hour, the solutions were placed at 4°C overnight to obtain stock solutions of polysaccharide of 2.0%, 3%, 4%, and 5.0%d.

[0012] In step (3) above, the whey protein isolate solution is prepared by dissolving whey protein isolate in ultrapure water to prepare a whey protein isolate solution with a mass fraction of 25%. The solution is then placed at 25°C and magnetically stirred at 500 r / min for 1 hour and then placed at 4°C overnight to dissolve the protein completely, thus obtaining the whey protein isolate solution.

[0013] In step (4) above, the preparation of the *Clerodendrum trichotomum* polysaccharide-whey protein isolate mixture is as follows: Take the 2.0%, 3%, 4%, and 5.0%d *Clerodendrum trichotomum* polysaccharide stock solutions from step (2) and the whey protein isolate solution from step (3) at a volume ratio of 1:0.5-1.5. Place them in a magnetic stirring system at a temperature of 21-35℃ and a rotation speed of 180-450r / min for 22-45 minutes until uniform. Then adjust the pH to 5.0-8.0 to obtain the *Clerodendrum trichotomum* polysaccharide-whey protein isolate mixture with polysaccharide concentrations of 1.0%, 1.5%, 2.0%, and 2.5%, respectively.

[0014] Specifically, in step (4) above, the preparation of the *Clerodendrum trichotomum* polysaccharide-whey protein isolate mixture is as follows: Take the 2.0%, 3%, 4%, and 5.0%d *Clerodendrum trichotomum* polysaccharide stock solutions from step (2) and mix them with the whey protein isolate solution from step (3) at a volume ratio of 1:1. Place them in a magnetic stirring system at 25°C and 300r / min for 30 minutes until homogeneous. Then adjust the pH to 7.0 to obtain the *Clerodendrum trichotomum* polysaccharide-whey protein isolate mixture with polysaccharide concentrations of 1.0%, 1.5%, 2.0%, and 2.5%, respectively.

[0015] In step (5) above, thermal gelation: the 1.0%, 1.5%, 2.0%, and 2.5% polysaccharide-whey protein isolate mixtures from step (4) are placed in a water bath at 85-110℃ and heated for 22-43 minutes, then cooled to room temperature in an ice water bath, sealed, and refrigerated at 3-6℃ overnight to obtain polysaccharide-whey protein isolate composite gels with polysaccharide concentrations of 1.0%, 1.5%, 2.0%, and 2.5%.

[0016] Specifically, in step (5) above, thermal gelation: the 1.0%, 1.5%, 2.0%, and 2.5% polysaccharide-whey protein isolate mixtures from step (4) are placed in a 95°C water bath and heated for 30 minutes, then cooled to room temperature in an ice water bath, sealed, and refrigerated at 4°C overnight to obtain polysaccharide-whey protein isolate composite gels with polysaccharide concentrations of 1.0%, 1.5%, 2.0%, and 2.5%.

[0017] This invention also discloses the application of the *Clerodendrum trichotomum* polysaccharide-whey protein isolate composite gel prepared by the above preparation method in the preparation of food processing gel matrix, characterized in that, when the food is yogurt or jelly, the composite gel is used to improve the stability, water retention and mouthfeel characteristics of the yogurt or jelly.

[0018] Beneficial effects of this invention: 1. The composite gel of this invention, through the synergistic effect of polysaccharide from *Clerodendrum trichotomum* (PLP) and whey protein isolate (WPI), effectively compensates for the poor stability and mechanical properties of single WPI gels, as well as the difficulty of single PLP in forming a complete three-dimensional network gel, significantly improving the gel's water-holding capacity, gel strength, and overall stability. Compared with single whey protein isolate gel, its water-holding capacity is increased by up to 12.13%, effectively reducing water separation during processing and storage, and extending the product's shelf life; its hardness is increased by up to 485.28%, and its elasticity by up to 102.5%, significantly improving the gel's toughness and textural properties, avoiding problems such as easy breakage and deformation; at the same time, this composite gel has obvious shear-thinning characteristics, allowing for adjustment of fluidity according to processing requirements during food processing, facilitating pipeline transportation, mixing, and other processes, reducing processing difficulty, improving production efficiency, and effectively overcoming the application limitations of single gels in high-end food processing.

[0019] 2. The raw materials are selected from the medicinal and edible plant *Clerodendrum trichotomum* and food-grade whey protein isolate, with no chemical additives and extremely high safety. *Clerodendrum trichotomum*, an abundant renewable plant resource in Southwest my country, possesses polysaccharides with natural biological activities such as antioxidant and anti-inflammatory properties. Combined with the nutritional advantages of whey protein isolate, the composite gel not only has excellent processing characteristics but also certain nutritional and health benefits. This achieves high-value utilization of *Clerodendrum trichotomum* resources, alleviates the current waste of natural functional raw materials, aligns with the modern food development trend of "natural, healthy, and nutritious," meets consumer demand for healthy food, and enhances the product's market competitiveness.

[0020] 3. This invention employs a thermogelation method to prepare composite gels. The preparation steps are simple and clear, and the reaction conditions are mild and easily controlled (heating temperature 95℃, pH 7.0±0.1). It requires no complex production equipment or special processes, has low operational difficulty, and can effectively reduce equipment investment, labor input, and energy consumption during the production process, significantly reducing production costs. Simultaneously, the mild reaction conditions can maximize the preservation of the bioactivity of PLP and the nutritional components of WPI, avoiding the damage to raw material properties caused by high temperatures and extreme acid / alkali conditions. Furthermore, the process exhibits strong stability and is easy to standardize and scale up production, solving the problems of complex preparation processes, high production costs, and difficulty in large-scale promotion of existing polysaccharide-protein composite gels.

[0021] 4. This composite gel, with its excellent water-holding capacity, stability, and textural properties, can be widely used in multiple food and health product fields, demonstrating extremely high industrial application value. In the dairy industry, it can be added to products such as yogurt to effectively prevent whey separation, improve the taste and stability of yogurt, and enhance the quality of dairy products. In the snack food industry, it can be used in the preparation of products such as jelly and pudding, significantly improving the product's toughness, taste, and shelf life, and enriching the product's flavor and texture. In the health product industry, it can serve as an active ingredient carrier in the preparation of products such as capsules, protecting the active ingredients from degradation while enabling the slow release of active ingredients, thus enhancing the efficacy of health products. Furthermore, the promotion and application of this composite gel can further expand the application fields of *Clerodendrum trichotomum* resources, promote the modernization and industrialization of traditional medicinal and edible plant resources, enrich the application scenarios of whey protein isolate, and drive the upgrading of related food and health product industries. Attached Figure Description

[0022] Figure 1 PLP-WPI composite gel diagrams with different PLP addition amounts; Figure 2 WHC (%) of PLP-WPI composite gel at different PLP concentrations (* indicates significance); Figure 3 TGA using PLP-WPI composite gel at different PLP concentrations; Figure 4 : DTG of PLP-WPI composite gel at different PLP concentrations; Figure 5 Rheological properties of apparent viscosity changes in PLP-WPI composite gels with different PLP concentrations; Figure 6 Rheological properties of G' variation in PLP-WPI composite gels with different PLP concentrations; Figure 7 Rheological properties of G'' variation in PLP-WPI composite gels with different PLP concentrations; Figure 8Rheological properties of PLP-WPI composite gels with different PLP concentrations, showing the change in tanδ. Detailed Implementation

[0023] To enable those skilled in the art to better understand and implement the technical solutions of the present invention, the present invention will be further described below with reference to specific embodiments, but the embodiments are not intended to limit the present invention.

[0024] Example 1: Preparation method of polysaccharide-whey protein isolate composite gel from *Clerodendrum trichotomum* (1) Extraction of polysaccharides from *Clerodendrum trichotomum*: Fresh leaves of *Clerodendrum trichotomum* were dried, crushed, and passed through an 80-mesh sieve to obtain *Clerodendrum trichotomum* powder. The powder was mixed with ultrapure water at a mass ratio of 1:30, and the pH was adjusted to 2 with tartaric acid. The mixture was extracted in a 90℃ water bath for 2 hours, with stirring every 10 minutes. After filtration, the filtrate was concentrated to 1 / 3 of its volume. Two times the volume of 95% ethanol was added to the filtrate, and the mixture was allowed to stand at 4℃ for 1 hour. The mixture was then centrifuged at 4500 r / min for 5 minutes. The collected precipitate was dried at 60℃ for 6-8 hours to obtain *Clerodendrum trichotomum* polysaccharide extract for later use. (2) Preparation of polysaccharide stock solution of *Clerodendrum trichotomum*: Dissolve the polysaccharide extract of *Clerodendrum trichotomum* in ultrapure water to prepare polysaccharide solutions with mass fractions of 2.0%, 3%, 4%, and 5.0%, respectively. Place the solutions at 25°C and 500 r / min with magnetic stirring for 1 hour and then place them at 4°C overnight to obtain polysaccharide stock solutions of 2.0%, 3%, 4%, and 5.0%d for later use. (3) Preparation of whey protein isolate solution: Dissolve whey protein isolate in ultrapure water to prepare a whey protein isolate solution with a mass fraction of 25%. Place it in a magnetic stirring environment at 25℃ and 500r / min for 1 hour, and then place it at 4℃ overnight to dissolve the protein completely. The whey protein isolate solution is then ready for use. (4) Preparation of the mixed solution of *Clerodendrum tigrinum* polysaccharide and whey protein isolate: Take the 2.0%, 3%, 4%, and 5.0%d *Clerodendrum tigrinum* polysaccharide stock solutions from step (2) and mix them with the whey protein isolate solution from step (3) at a volume ratio of 1:1. Place them in a magnetic stirrer at 25℃ and 300r / min for 30min until homogeneous. Adjust the pH to 7.0 to obtain mixed solutions of *Clerodendrum tigrinum* polysaccharide and whey protein isolate with polysaccharide concentrations of 1.0%, 1.5%, 2.0%, and 2.5%, respectively, for later use. (5) Thermal gelation: The 1.0%, 1.5%, 2.0%, and 2.5% polysaccharide-whey protein isolate mixtures from step (4) were placed in a water bath at 85-110℃ and heated for 22-43 minutes, followed by cooling in an ice water bath to room temperature. After sealing, they were refrigerated at 3-6℃ overnight to obtain polysaccharide-whey protein isolate composite gels with polysaccharide concentrations of 1.0%, 1.5%, 2.0%, and 2.5%.

[0025] Example 2: Preparation method of polysaccharide-whey protein isolate composite gel from *Bromhidrosis pilosula* (1) Extraction of polysaccharides from *Clerodendrum trichotomum*: Fresh leaves of *Clerodendrum trichotomum* were dried, crushed, and passed through a 50-mesh sieve to obtain *Clerodendrum trichotomum* powder. The powder was mixed with ultrapure water at a mass ratio of 1:10. The pH was adjusted to 1 with tartaric acid and extracted in a 75°C water bath for 0.5 h, with stirring every 10 min. After filtration, the filtrate was concentrated to 1 / 5 of its volume. 0.5 times the volume of 95% ethanol was added to the filtrate and allowed to stand at 0°C for 0.1 h. The filtrate was then centrifuged at 2500 r / min for 1 min. The collected precipitate was dried at 44°C for 1 h to obtain *Clerodendrum trichotomum* polysaccharide extract for later use. (2) Preparation of polysaccharide stock solution of *Clerodendrum trichotomum*: Dissolve the polysaccharide extract of *Clerodendrum trichotomum* in ultrapure water to prepare polysaccharide solutions with mass fractions of 2.0%, 3%, 4%, and 5.0%, respectively. Place the solutions at 10℃ and 300r / min for 0.5 minutes with magnetic stirring and then place them at 0℃ overnight to obtain polysaccharide stock solutions of 2.0%, 3%, 4%, and 5.0%d for later use. (3) Preparation of whey protein isolate solution: Dissolve whey protein isolate in ultrapure water to prepare a whey protein isolate solution with a mass fraction of 25%. Place it in a magnetic stirring environment at 10℃ and 300r / min for 0.5h, and then place it at 0℃ overnight to dissolve the protein completely. The whey protein isolate solution is then ready for use. (4) Preparation of the mixed solution of *Clerodendrum trichotomum* polysaccharide and whey protein isolate: Take the 2.0%, 3%, 4%, and 5.0%d *Clerodendrum trichotomum* polysaccharide stock solutions from step (2) and the whey protein isolate solution from step (3) respectively at a volume ratio of 1:0.1. Place them in a magnetic stirrer at 10℃ and 100r / min for 10min until uniform. Adjust the pH to 4.0 to obtain mixed solutions of *Clerodendrum trichotomum* polysaccharide and whey protein isolate with polysaccharide concentrations of 1.0%, 1.5%, 2.0%, and 2.5% respectively, for later use. (5) Thermal gelation: The 1.0%, 1.5%, 2.0% and 2.5% polysaccharide-whey protein isolate mixtures from step (4) were placed in a 70°C water bath and heated for 5 minutes, then cooled to room temperature in an ice water bath, sealed and refrigerated at 0°C overnight to obtain polysaccharide-whey protein isolate composite gels with polysaccharide concentrations of 1.0%, 1.5%, 2.0% and 2.5%.

[0026] Example 3: Preparation method of polysaccharide-whey protein isolate composite gel from *Clerodendrum trichotomum* (1) Extraction of polysaccharides from *Clerodendrum trichotomum*: Fresh leaves of *Clerodendrum trichotomum* were dried, crushed, and passed through a 70-mesh sieve to obtain *Clerodendrum trichotomum* powder. The powder was mixed with ultrapure water at a mass ratio of 1:20. The pH was adjusted to 2 with tartaric acid and extracted in a water bath at 86℃ for 1 hour, with stirring every 10 minutes. After filtration, the filtrate was concentrated to 1 / 4 volume. 95% ethanol was added to the filtrate at a volume equal to 1 filtrate volume. The mixture was allowed to stand at 2℃ for 0.5 hours and centrifuged at 3500 r / min for 3 minutes. The collected precipitate was dried at 55℃ for 3 hours to obtain *Clerodendrum trichotomum* polysaccharide extract for later use. (2) Preparation of polysaccharide stock solution of *Clerodendrum trichotomum*: Dissolve the polysaccharide extract of *Clerodendrum trichotomum* in ultrapure water to prepare polysaccharide solutions with mass fractions of 2.0%, 3%, 4%, and 5.0%, respectively. After stirring magnetically at 20°C and 400 r / min for 1 h, place at 2°C overnight to obtain polysaccharide stock solutions of 2.0%, 3%, 4%, and 5.0%d for later use. (3) Preparation of whey protein isolate solution: Dissolve whey protein isolate in ultrapure water to prepare a whey protein isolate solution with a mass fraction of 25%. Place it in a magnetic stirring environment at 20℃ and 400r / min for 1 hour, and then place it at 2℃ overnight to dissolve the protein completely. The whey protein isolate solution is then ready for use. (4) Preparation of the mixed solution of *Clerodendrum trichotomum* polysaccharide and whey protein isolate: Take the 2.0%, 3%, 4%, and 5.0%d *Clerodendrum trichotomum* polysaccharide stock solutions from step (2) and the whey protein isolate solution from step (3) at a volume ratio of 1:0.5. Place them in a magnetic stirrer at 21℃ and 180r / min for 22min until uniform. Adjust the pH to 5.0 to obtain mixed solutions of *Clerodendrum trichotomum* polysaccharide and whey protein isolate with polysaccharide concentrations of 1.0%, 1.5%, 2.0%, and 2.5%, respectively, for later use. (5) Thermal gelation: The 1.0%, 1.5%, 2.0% and 2.5% polysaccharide-whey protein isolate mixtures from step (4) were placed in an 85°C water bath and heated for 22 min, then cooled to room temperature in an ice water bath, sealed and refrigerated at 3°C ​​overnight to obtain polysaccharide-whey protein isolate composite gels with polysaccharide concentrations of 1.0%, 1.5%, 2.0% and 2.5%.

[0027] Example 4: Preparation method of polysaccharide-whey protein isolate composite gel from *Bromhidrosis pilosula* (1) Extraction of polysaccharides from *Clerodendrum trichotomum*: Fresh leaves of *Clerodendrum trichotomum* were dried, crushed, and passed through a 90-mesh sieve to obtain *Clerodendrum trichotomum* powder. The powder was mixed with ultrapure water at a mass ratio of 1:40. The pH was adjusted to 3 with tartaric acid and extracted in a 98℃ water bath for 3 hours, with stirring every 10 minutes. After filtration, the filtrate was concentrated to 1 / 2 volume. Three times the volume of 95% ethanol was added to the filtrate, and the mixture was allowed to stand at 7℃ for 2 hours. The mixture was then centrifuged at 5500 r / min for 6 minutes. The collected precipitate was dried at 70℃ for 9 hours to obtain *Clerodendrum trichotomum* polysaccharide extract for later use. (2) Preparation of polysaccharide stock solution of *Clerodendrum trichotomum*: Dissolve the polysaccharide extract of *Clerodendrum trichotomum* in ultrapure water to prepare polysaccharide solutions with mass fractions of 2.0%, 3%, 4%, and 5.0%, respectively. Place the solutions in a magnetic stirring environment at 30℃ and 550 r / min for 1.5 h, and then place them at 5℃ overnight to obtain polysaccharide stock solutions of 2.0%, 3%, 4%, and 5.0%d for later use. (3) Preparation of whey protein isolate solution: Dissolve whey protein isolate in ultrapure water to prepare a whey protein isolate solution with a mass fraction of 25%. Place it in a magnetic stirring environment at 30℃ and 550r / min for 1.5h, and then place it at 5℃ overnight to dissolve the protein completely. The whey protein isolate solution is then ready for use. (4) Preparation of the mixed solution of *Clerodendrum trichotomum* polysaccharide and whey protein isolate: Take the 2.0%, 3%, 4%, and 5.0%d *Clerodendrum trichotomum* polysaccharide stock solutions from step (2) and the whey protein isolate solution from step (3) respectively at a volume ratio of 1:1.5. Place them in a magnetic stirrer at 35℃ and 450r / min for 45min until uniform. Adjust the pH to 8.0 to obtain mixed solutions of *Clerodendrum trichotomum* polysaccharide and whey protein isolate with polysaccharide concentrations of 1.0%, 1.5%, 2.0%, and 2.5% respectively, for later use. (5) Thermal gelation: The 1.0%, 1.5%, 2.0% and 2.5% polysaccharide-whey protein isolate mixtures from step (4) were placed in a 110°C water bath and heated for 43 min, then cooled to room temperature in an ice water bath, sealed and refrigerated at 6°C overnight to obtain polysaccharide-whey protein isolate composite gels with polysaccharide concentrations of 1.0%, 1.5%, 2.0% and 2.5%.

[0028] Example 5: Preparation method of polysaccharide-whey protein isolate composite gel from *Clerodendrum trichotomum* (1) Extraction of polysaccharides from *Clerodendrum trichotomum*: Fresh leaves of *Clerodendrum trichotomum* were dried, crushed, and passed through a 100-mesh sieve to obtain *Clerodendrum trichotomum* powder. The powder was mixed with ultrapure water at a mass ratio of 1:50, and the pH was adjusted to 5 with tartaric acid. The mixture was extracted in a water bath at 105℃ for 4 hours, with stirring every 10 minutes. After filtration, the filtrate was concentrated to 1 volume. 4.5 times the volume of 95% ethanol was added to the filtrate, and the mixture was allowed to stand at 10℃ for 2.5 hours. The mixture was then centrifuged at 7000 r / min for 10 minutes. The collected precipitate was dried at 78℃ for 10 hours to obtain *Clerodendrum trichotomum* polysaccharide extract for later use. (2) Preparation of polysaccharide stock solution of *Clerodendrum trichotomum*: Dissolve the polysaccharide extract of *Clerodendrum trichotomum* in ultrapure water to prepare polysaccharide solutions with mass fractions of 2.0%, 3%, 4%, and 5.0%, respectively. After stirring with a magnetic force at 45℃ and 650 r / min for 2 hours, the solutions were placed at 6℃ overnight to obtain polysaccharide stock solutions of 2.0%, 3%, 4%, and 5.0%d for later use. (3) Preparation of whey protein isolate solution: Dissolve whey protein isolate in ultrapure water to prepare a whey protein isolate solution with a mass fraction of 25%. Place it in a magnetic stirring environment at 45℃ and 650 r / min for 2 hours, and then place it at 6℃ overnight to dissolve the protein completely. The whey protein isolate solution is then ready for use. (4) Preparation of the mixed solution of *Clerodendrum trichotomum* polysaccharide and whey protein isolate: Take the 2.0%, 3%, 4%, and 5.0%d *Clerodendrum trichotomum* polysaccharide stock solutions from step (2) and mix them with the whey protein isolate solution from step (3) at a volume ratio of 1:3. Place them in a magnetic stirrer at 45℃ and 550r / min for 55 minutes until homogeneous. Adjust the pH to 10.0 to obtain mixed solutions of *Clerodendrum trichotomum* polysaccharide and whey protein isolate with polysaccharide concentrations of 1.0%, 1.5%, 2.0%, and 2.5%, respectively, for later use. (5) Thermal gelation: The 1.0%, 1.5%, 2.0% and 2.5% polysaccharide-whey protein isolate mixtures from step (4) were placed in a 120°C water bath and heated for 55 minutes, then cooled to room temperature in an ice water bath, sealed and refrigerated at 10°C overnight to obtain polysaccharide-whey protein isolate composite gels with polysaccharide concentrations of 1.0%, 1.5%, 2.0% and 2.5%.

[0029] To obtain the solution and verify the technical effects of this invention, the inventors conducted extensive experimental research, some of which are recorded below: 1. Experimental Materials The leaves of *Clerodendrum trichotomum* used in this experiment were taken from plants grown in Wuchuan Gelao and Miao Autonomous County, Guizhou Province; the whey protein isolate raw material was purchased from Wankang Biotechnology Co., Ltd.; and the ultrapure water was deionized water prepared in the laboratory.

[0030] 2. Experimental methods and procedures 2.1 Preparation of PLP-WPI composite gel 2.1.1 Extraction of polysaccharide (PLP) from *Bromhidrosis pilosula* Fresh leaves of *Clerodendrum trichotomum* were collected, impurities removed, and the leaves were washed and dried in a drying oven. The dried leaves were then pulverized using a high-speed universal pulverizer and passed through an 80-mesh sieve to obtain *Clerodendrum trichotomum* leaf powder, which was then sealed and stored for later use. Tartaric acid solution was used as the extraction solvent, and the mixture was prepared at a ratio of 1:30 (g / mL, powder mass: extractant volume). The pH of the mixture was adjusted to 2.00 using a precision pH meter, and the mixture was extracted in a 90℃ constant temperature water bath for 120 min. After extraction, the mixture was vacuum filtered using qualitative filter paper to remove the filter residue. The resulting filtrate was then concentrated to 1 / 3 of its original volume in a rotary evaporator at 60℃ and 0.08 MPa. After cooling the concentrate to room temperature, two volumes of 95% ethanol were slowly added while stirring to ensure complete precipitation of the polysaccharides. The mixture was then placed in a 4℃ refrigerator and allowed to stand for 1 h to accelerate precipitation. After standing, the mixture was centrifuged in a high-speed refrigerated centrifuge at 4500 r / min for 5 min. The supernatant was discarded, and the bottom precipitate was collected. The precipitate was dried in a drying oven to obtain the polysaccharide extract of *Clerodendrum trichotomum*, which was then set aside for later use.

[0031] 2.1.2 Preparation of stock solutions of *Clerodendrum trichotomum* polysaccharides at concentrations of 2.0%, 3%, 4%, and 5.0% Weigh out the purified polysaccharide extract from *Clerodendrum trichotomum*, dissolve it in ultrapure water, and prepare PLP solutions with different mass fractions of 2.0%, 3%, 4%, and 5.0%. Stir magnetically at 500 r / min for 1 h at 25℃, and then dissolve overnight in a refrigerator at 4℃ to obtain stock solutions of 2.0%, 3%, 4%, and 5.0%d *Clerodendrum trichotomum* polysaccharide for later use.

[0032] Accurately weigh a certain amount of *Clerodendrum trichotomum* polysaccharide extract and place it in four clean beakers. Add an appropriate amount of ultrapure water to prepare PLP solutions with mass fractions of 2.0%, 3.0%, 4.0%, and 5.0%, respectively. Place the beakers on a magnetic stirrer and stir at 500 r / min for 1 h at room temperature (25°C) to allow the polysaccharides to initially dissolve. Then seal the beakers and place them in a refrigerator at 4°C overnight to dissolve completely, ensuring that the polysaccharides are completely dissolved and free of particulate matter. This yields stock solutions of *Clerodendrum trichotomum* polysaccharides with concentrations of 2.0%, 3.0%, 4.0%, and 5.0%, which are then sealed and stored for later use.

[0033] 2.1.3 Preparation of whey protein isolate solution Accurately weigh an appropriate amount of whey protein isolate and place it in a clean beaker. Add ultrapure water to prepare a 25% (w / w) whey protein isolate solution. Place the beaker on a magnetic stirrer and stir at 500 rpm for 1 hour at room temperature (25°C) to allow the whey protein isolate to initially dissolve, avoiding clumping. Then seal the beaker and place it in a refrigerator at 4°C overnight to dissolve completely, ensuring the whey protein isolate is completely dissolved and a homogeneous, transparent whey protein isolate solution is obtained. Store the solution in a sealed container for later use.

[0034] 2.1.4 Preparation of PLP-WPI composite gels under different concentration conditions Take the prepared WPI solution and add it to four clean beakers at a volume ratio of 1:1 with 2.0%, 3.0%, 4.0%, and 5.0% PLP stock solutions, respectively, to obtain four mixed systems. Place each beaker on a magnetic stirrer and stir at 300 r / min for 30 min at room temperature (25°C) to ensure thorough mixing of the WPI solution and PLP stock solution. After stirring, adjust the pH of each mixed system to 7.0 using a precision pH meter with 0.1 mol / L NaOH solution or 0.1 mol / L HCl solution, obtaining composite gel mixtures with final PLP concentrations of 1.0%, 1.5%, 2.0%, and 2.5% (final PLP concentration = PLP stock solution mass fraction × 1 / 2, since the WPI solution and PLP stock solution are mixed in equal volumes).

[0035] The above four composite gel mixtures were poured into molds and placed in a 95°C constant temperature water bath. After heating at a constant temperature for 30 minutes, the molds were quickly placed in ice water to cool for 15 minutes to allow the gels to set rapidly. The molds were then sealed and stored in a 4°C refrigerator overnight to stabilize the gel structure, thus obtaining PLP-WPI composite gels with final PLP concentrations of 1.0%, 1.5%, 2.0%, and 2.5%, respectively, for later use.

[0036] 3 Performance testing of composite gels at different PLP concentrations The method described in Section 3.1 was used to uniformly test the performance indicators of PLP-WPI composite gels with four different PLP concentrations. Each sample was tested in parallel three times, and the mean ± standard deviation was taken as the final test result to ensure the reliability of the experimental data.

[0037] 3.1 Test Method 3.1.1 Water-holding capacity test (centrifugation method) Accurately weigh a certain mass (m0, unit: g) of the composite gel sample and place it in a pre-weighed centrifuge tube (m1, unit: g). Centrifuge the tube in a high-speed refrigerated centrifuge at 3000 r / min and 4℃ for 15 min. After centrifugation, carefully pour out the supernatant from the centrifuge tube, blot the water off the outer wall of the centrifuge tube with filter paper, and accurately weigh the total mass of the centrifuge tube and the remaining gel (m2, unit: g). Calculate the water-holding capacity of the composite gel using the following formula: Water holding capacity (%) = (m2 - m1) / m0 × 100% Where m0 is the initial mass of the gel sample, m1 is the mass of the centrifuge tube, and m2 is the total mass of the centrifuge tube and the remaining gel after centrifugation.

[0038] 3.1.2 Texture parameter testing (texture profile analysis, TPA) The composite gel samples were removed from the 4℃ refrigerator and allowed to reach room temperature (25℃). They were then cut into cylindrical samples with a diameter of 20 mm and a height of 15 mm for later use. TPA testing was performed using a texture analyzer under the following conditions: a P / 36R cylindrical probe was used; the initial velocity was 1 mm / s, the testing velocity was 0.5 mm / s, and the post-test velocity was 1 mm / s; the compression ratio was 50%; the trigger force was 5 g; and the interval between two compressions was 5 s. Three different sites were selected for testing on each sample, and four textural parameters were recorded simultaneously: hardness (the maximum force required for compression, unit: N), elasticity (the ability of the sample to return to its original shape after compression, unit: ), resilience (the ability of the sample to return to its original height after compression, unit: ), and adhesiveness (the viscous resistance of the sample to deformation during chewing, unit: N). The mean ± standard deviation was calculated for subsequent textural property analysis.

[0039] 3.1.3 tanδ value test (dynamic rheological test) Dynamic rheological tests were performed on the composite gel samples using a rotational rheometer to analyze their tanδ values ​​(loss tangent, reflecting the viscoelasticity of the gel; tanδ < 1 indicates elastic dominance, tanδ > 1 indicates viscous dominance). Gel samples were cut into circular slices 2 mm thick and 25 mm in diameter, placed between parallel plates of the rheometer with a plate spacing of 1.8 mm. A small amount of petroleum jelly was applied around the samples to prevent moisture evaporation. Test conditions: temperature 25℃, frequency scan range 0.1-10 Hz, strain value 1% (within the linear viscoelastic range of the sample). Tanδ values ​​at different frequencies were recorded, and the tanδ value at 1 Hz was taken as the final test result. If the tanδ value fluctuated within a certain range during the test, the fluctuation range was recorded.

[0040] 3.1.4 Thermal decomposition temperature test (thermogravimetric analysis, TGA) Thermogravimetric analysis (TGA) was used to test the thermal stability of the composite gel samples and determine their thermal decomposition temperature. 5-8 mg of the composite gel sample was accurately weighed and placed in an alumina crucible, with an empty alumina crucible serving as a blank control. The test conditions were set as follows: nitrogen atmosphere (nitrogen flow rate 50 mL / min), heating rate 10℃ / min, and a heating range from room temperature (25℃) to 500℃. Thermogravimetric curves (TG curves) and differential thermogravimetric curves (DTG curves) of the sample mass as a function of temperature were recorded. The temperature corresponding to the maximum weight loss rate in the DTG curve was taken as the thermal decomposition temperature of the composite gel, reflecting its thermal stability.

[0041] 3.2 Performance test results and analysis of composite gel with PLP concentration of 1.0% (1% PLP + 12.5% ​​WPI) Following the test methods described in Section 3.1 above, various performance tests were conducted on the PLP-WPI composite gel with a final PLP concentration of 1.0% (ratio of 1% PLP + 12.5% ​​WPI). The test results are as follows: the composite gel has a water holding capacity of 71.58±2.13%, a hardness of 3.60±0.26 N, an elasticity of 0.40±0.02, a recovery force of 0.14±0.01, an adhesiveness of 15.60±3.01 N, a tanδ value of 0.7-0.9, and a thermal decomposition temperature of 198.8℃. At this concentration, the gel exhibits poor water holding capacity, low hardness and elasticity, high adhesiveness, with viscoelasticity predominantly viscous, and good thermal stability.

[0042] 3.3 Performance test results and analysis of composite gel with 1.5% PLP concentration (1.5% PLP + 12.5% ​​WPI) Following the test methods described in Section 3.1 above, various performance tests were conducted on the PLP-WPI composite gel with a final PLP concentration of 1.5% (ratio of 1.5% PLP + 12.5% ​​WPI). The test results are as follows: the composite gel exhibits a water retention of 80.26±1.87%, a hardness of 16.67±3.74 N, an elasticity of 0.59±0.09, a recovery force of 0.16±0.03, an adhesiveness of 11.30±0.98 N, a tanδ value of 0.5-0.8, and a thermal decomposition temperature of 198.3℃. At this concentration, the gel achieves optimal water retention, significantly improves hardness and elasticity compared to the 1.0% concentration, noticeably decreases adhesiveness, improves viscoelasticity, and maintains good thermal stability.

[0043] 3.4 Performance test results and analysis of composite gel with PLP concentration of 2.0% (2% PLP + 12.5% ​​WPI) Following the test methods described in Section 3.1 above, various performance tests were conducted on the PLP-WPI composite gel with a final PLP concentration of 2.0% (ratio of 2% PLP + 12.5% ​​WPI). The test results are as follows: the composite gel has a water holding capacity of 79.83±2.05%, a hardness of 20.67±0.71 N, an elasticity of 0.64±0.07, a recovery force of 0.17±0.01, an adhesiveness of 10.73±3.57 N, a tanδ value of 0.4-0.7, and a thermal decomposition temperature of 198.4℃. At this concentration, the water holding capacity of the gel is slightly lower than that at the 1.5% concentration, while the hardness and elasticity continue to improve, the adhesiveness remains at a low level, the viscoelasticity is further improved, and the thermal stability is stable.

[0044] 3.5 Performance test results and analysis of composite gel with 2.5% PLP concentration (2.5% PLP + 12.5% ​​WPI) Following the test methods described in Section 3.1 above, various performance tests were conducted on the PLP-WPI composite gel with a final PLP concentration of 2.5% (ratio of 2.5% PLP + 12.5% ​​WPI). The test results are as follows: the composite gel exhibits a water retention of 78.95±1.92%, a hardness of 21.07±1.24 N, an elasticity of 0.81±0.14, a recovery force of 0.18±0.02, an adhesiveness of 9.27±2.64 N, a tanδ value of 0.3-0.6, and a thermal decomposition temperature of 198.8℃. At this concentration, the gel achieves optimal hardness and elasticity, with a slight decrease in water retention and the lowest adhesiveness. Viscoelasticity is predominantly elastic, and thermal stability is good, resulting in optimal overall performance.

[0045] Experimental Data Summary Table Table 1: Comprehensive performance test results of composite gels at different PLP concentrations (n=3, mean ± standard deviation) Table 2: Texture parameters of PLP-WPI composite gels with different PLP addition amounts (n=3, mean ± standard deviation) 4.1 Experimental Conclusions Based on the above performance test methods, test results, and data summary analysis in Tables 1 and 2, it can be seen that the performance of the PLP-WPI composite gel prepared in this invention (all four ratios are PLP concentration gradients combined with 12.5% ​​WPI) shows a significant correlation with the PLP concentration, and the textural properties exhibit a regular change: with the increase of PLP concentration, the water-holding capacity, hardness, elasticity, and resilience of the composite gel all show a significant increasing trend, while the adhesiveness shows a significant decreasing trend; among them, the water-holding capacity reaches its peak (80.26±1.87%) at a PLP concentration of 1.5%, and then decreases slightly; the hardness and elasticity reach their optimal values ​​at a PLP concentration of 2.5%, which are 21.07±1.24 N and 0.81±0.14 N, respectively, while the adhesiveness is the lowest at this concentration (9.27±2.64 N), indicating the best texture.

[0046] As can be seen from the significance analysis of the textural parameters in Table 2, in terms of hardness, the 1% PLP group was significantly different from the 1.5%, 2%, and 2.5% PLP groups (P<0.05), the 1.5% and 2% PLP groups were not significantly different (P>0.05), and the 2% and 2.5% PLP groups were significantly different (P<0.05). In terms of elasticity, the 1% PLP group was significantly different from the other three groups (P<0.05), while the 1.5%, 2%, and 2.5% PLP groups were not significantly different (P>0.05). This indicates that after the PLP concentration reaches 1.5%, the effect of improving gel elasticity tends to level off, while the effect of improving hardness continues until the concentration reaches 2.5%.

[0047] Thermal stability tests showed that the thermal decomposition temperatures of the composite gels with four different PLP concentrations remained stable between 198.3 and 198.8 °C with minimal fluctuations, indicating that the addition of PLP did not significantly affect the thermal stability of the composite gels. These gels exhibit good thermal stability and can meet the high-temperature processing requirements in food processing. Dynamic rheological tests showed that with increasing PLP concentration, the tanδ value of the composite gels gradually decreased, from 0.7-0.9 (viscosity-dominated) at a 1.0% concentration to 0.3-0.6 (elasticity-dominated) at a 2.5% concentration. This indicates that the addition of PLP can promote the cross-linking polymerization of WPI, improve the viscoelasticity of the gel, and transform the gel from viscosity-dominated to elastic-dominated, forming a pseudoplastic weak gel. Combined with the decreasing trend of adhesive viscosity in the texture parameters, this further demonstrates that PLP can effectively optimize gel texture, meeting the core requirements for gel texture and stability in food processing.

[0048] In summary, the optimal performance range of PLP-WPI composite gels is clearly defined: if good water retention is a priority in food processing, such as yogurt, a composite gel with a PLP concentration of 1.5% (ratio of 1.5% PLP + 12.5% ​​WPI) can be selected, as it has the best water retention and moderate adhesiveness, which can improve the product's water separation problem; if higher hardness, elasticity, and good chewiness are prioritized (such as jelly, meat products, etc.), a composite gel with a PLP concentration of 2.5% (ratio of 2.5% PLP + 12.5% ​​WPI) can be selected, as it has the best textural parameters and can improve the product's toughness and taste; the appropriate PLP concentration of composite gel can be flexibly selected according to the specific needs of food processing, and its application prospects are broad.

[0049] 5. Research on the food application of PLP-WPI composite gel 5.1 Application in yogurt production A PLP-WPI composite gel with a PLP concentration of 1.5% (corresponding to a PLP stock solution mass fraction of 3.0%, and a ratio of 1.5% PLP + 12.5% ​​WPI) was selected as a stabilizer for yogurt production. The addition amount was set at 5% (based on the total mass of yogurt). A blank control group of yogurt without any stabilizer was also set up. Both groups of experiments used the same yogurt production process. Preparation: A PLP-WPI composite gel with a PLP concentration of 1.5% is selected. During the ingredient preparation stage, this composite gel stabilizer is mixed with fresh milk and fully hydrated. Then, homogenization (50-70℃, 10-25 MPa) is performed to uniformly disperse the composite and adsorb it onto the surface of casein micelles. Heat treatment (80-95℃) is used for sterilization, promoting SPI extension and forming a three-dimensional network framework with PLP through electrostatic interaction and covalent cross-linking. Through the synergistic effect of electrostatic adsorption and steric hindrance, a dense and acid-resistant mixed gel structure is formed. During demulsification and cooling, the composite gel fills the spaces between protein clusters and locks in a large amount of water, ultimately forming yogurt.

[0050] Application effect testing method: The whey separation rate of yogurt was detected by centrifugation (3000 r / min, centrifugation for 10 min), and the proportion of whey separation to the total mass of yogurt was recorded; the two groups of yogurt were refrigerated in a 4℃ refrigerator, and the condition of the yogurt was observed daily, and its shelf life (the time when separation or off-odor appeared) was recorded; 10 professional tasters were invited to conduct sensory evaluation of the yogurt from three dimensions: taste, texture, and flavor (10 points).

[0051] The application results are as follows: In the experimental group with added PLP-WPI composite gel, the whey separation rate of yogurt was 2.1%, which was 68% lower than that of the blank control group; the shelf life was extended to 12-14 days, which was 3-5 days longer than that of the blank control group (9 days); the average sensory evaluation score was 9 points, while that of the blank control group was 7.2 points. The yogurt in the experimental group had a richer and smoother taste, no grainy texture, uniform texture, and pure flavor. It effectively improved the problems of easy water separation, short shelf life, and rough texture of traditional yogurt. This is closely related to the excellent water retention and moderate adhesiveness of the gel with this ratio.

[0052] 5.2 Application in jelly production A PLP-WPI composite gel with a PLP concentration of 2.5% (corresponding to a PLP stock solution mass fraction of 5.0%, and a ratio of 2.5% PLP + 12.5% ​​WPI) was selected as a gelling agent for jelly production, replacing traditional gelatin. The composite gel addition amount was set at 4% (based on the total mass of the jelly), and conventional jelly production processes were adopted. Preparation: Use a PLP-WPI composite gel with a PLP concentration of 2.5%. Add 4%-8% sucrose to the PLP-WPI composite gel and precisely adjust the pH to 10.0 with sodium hydroxide. This alkaline condition promotes the unfolding of protein molecular structure and the exposure of sulfhydryl groups, forming a uniform and dense three-dimensional network with polysaccharides through hydrogen bonds and hydrophobic interactions. Induce protein thermal denaturation by heating in a water bath for 30 minutes. Fill at a temperature above 80°C. Before filling, add 0.02%-0.08% citric acid to prevent protein acid denaturation and flocculation. After sealing, sterilize at 85-90°C under normal pressure for 10-30 minutes. Cool in stages and refrigerate at 4°C for at least 20 hours for post-ripening.

[0053] This process eliminates the need for traditional gelling agents such as carrageenan, resulting in a finished jelly with a uniform appearance, moderate elasticity, and a smooth texture, combining the nutritional fortification of SPI with the natural properties of PLP.

[0054] Application effect testing method: The toughness of the jelly was tested using a texture analyzer (probe P / 36R, test speed 1 mm / s, compression ratio 30%); the two groups of jelly were placed at room temperature of 25℃, sealed and stored, and the state of the jelly was observed daily, and its stability (time of deformation, water separation, and softening) was recorded; 10 professional tasters were invited to conduct sensory evaluation of the chewing texture and flavor of the jelly.

[0055] The application results are as follows: In the experimental group with added PLP-WPI composite gel, the jelly's toughness was 18.6 g·s, which was 45% higher than that of the gelatin control group (12.8 g·s). After being placed at room temperature of 25℃ for one month, the jelly showed no deformation, no water separation, and no softening, maintaining a uniform and elastic texture. In contrast, the gelatin control group showed slight softening and water separation after 20 days. The average sensory evaluation score was 8.9 points, while the control group scored 7.5 points. The experimental group's jelly had a better chewy texture, was chewy, did not stick to the teeth, and had a fresh flavor, significantly outperforming the stability and taste of traditional gelatin jelly. This is attributed to the excellent textural properties of this formula, which features high gel hardness, good elasticity, and low adhesiveness.

[0056] The above description is merely a preferred experimental example of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing a polysaccharide-whey protein isolate composite gel from *Clerodendrum trichotomum*, characterized in that, The preparation of the polysaccharide-whey protein isolate composite gel from *Bromhidrosis pilosula* was carried out according to the following steps: (1) Extraction of polysaccharides from *Clerodendrum trichotomum*: Fresh leaves of *Clerodendrum trichotomum* are dried, crushed, and passed through a 50-100 mesh sieve to obtain *Clerodendrum trichotomum* powder. The powder is mixed with ultrapure water at a mass ratio of 1:10-50, and the pH is adjusted to 1-5 with tartaric acid. The mixture is extracted in a water bath at 75-105℃ for 0.5-4h, with stirring every 10min. After filtration, the filtrate is concentrated to 1 / 5-1 volume. 0.5-4.5 times the volume of 95% ethanol is added to the filtrate. The mixture is allowed to stand at 0-10℃ for 0.1-2.5h, and then centrifuged at 2500-7000r / min for 1-10min. The collected precipitate is dried at 44-78℃ for 1-10h to obtain *Clerodendrum trichotomum* polysaccharide extract for later use. (2) Preparation of polysaccharide stock solution of *Clerodendrum trichotomum*: Dissolve the polysaccharide extract of *Clerodendrum trichotomum* in ultrapure water to prepare polysaccharide solutions with mass fractions of 2.0%, 3%, 4%, and 5.0%, respectively. Place the solutions in a magnetic stirring environment at 10-45℃ and 300-650 r / min for 0.5-2 h, and then place them at 0-6℃ overnight to obtain polysaccharide stock solutions of 2.0%, 3%, 4%, and 5.0%d for later use. (3) Preparation of whey protein isolate solution: Dissolve whey protein isolate in ultrapure water to prepare a whey protein isolate solution with a mass fraction of 25%. Place it in a magnetic stirring environment at a temperature of 10-45℃ and a speed of 300-650r / min for 0.5-2h, and then place it at 0-6℃ overnight to dissolve the protein completely. The whey protein isolate solution is then ready for use. (4) Preparation of the mixed solution of *Clerodendrum tigrinum* polysaccharide and whey protein isolate: Take the 2.0%, 3%, 4%, and 5.0%d *Clerodendrum tigrinum* polysaccharide stock solutions from step (2) and the whey protein isolate solution from step (3) at a volume ratio of 1:0.1-3. Place them in a magnetic stirring system at a temperature of 10-45℃ and a speed of 100-550r / min for 10-55min until uniform. Adjust the pH to 4.0-10.0 to obtain mixed solutions of *Clerodendrum tigrinum* polysaccharide and whey protein isolate with polysaccharide concentrations of 1.0%, 1.5%, 2.0%, and 2.5%, respectively, for later use. (5) Thermal gelation: The 1.0%, 1.5%, 2.0% and 2.5% polysaccharide-whey protein isolate mixtures from step (4) were placed in a water bath at 70-120℃ and heated for 5-55 minutes, then cooled to room temperature in an ice water bath, sealed and refrigerated at 0-10℃ overnight to obtain polysaccharide-whey protein isolate composite gels with polysaccharide concentrations of 1.0%, 1.5%, 2.0% and 2.5%.

2. The method for preparing the *Clerodendrum trichotomum* polysaccharide-whey protein isolate composite gel according to claim 1, characterized in that, In step (1), the extraction of polysaccharides from *Clerodendrum thomsoniae* is as follows: Fresh leaves of *Clerodendrum thomsoniae* are dried, crushed, and passed through a 70-90 mesh sieve to obtain *Clerodendrum thomsoniae* powder. The powder is mixed with ultrapure water at a mass ratio of 1:20-40, and the pH is adjusted to 2-3 with tartaric acid. The mixture is extracted in a water bath at 86-98℃ for 1-3 hours, with stirring every 10 minutes. After filtration, the filtrate is concentrated to 1 / 4-1 / 2 volume. 1-3 times the volume of 95% ethanol is added to the filtrate, and the mixture is allowed to stand at 2-7℃ for 0.5-2 hours. The mixture is then centrifuged at 3500-5500 r / min for 3-6 minutes. The collected precipitate is dried at 55-70℃ for 3-9 hours to obtain the polysaccharide extract from *Clerodendrum thomsoniae*.

3. The method for preparing the *Clerodendrum trichotomum* polysaccharide-whey protein isolate composite gel according to claim 2, characterized in that, In step (1), the extraction of polysaccharides from *Clerodendrum tigrinum* leaves is as follows: fresh leaves of *Clerodendrum tigrinum* are dried, crushed, and passed through an 80-mesh sieve to obtain *Clerodendrum tigrinum* powder. The powder is mixed with ultrapure water at a mass ratio of 1:30, and the pH is adjusted to 2 with tartaric acid. The mixture is extracted in a 90°C water bath for 2 hours, with stirring every 10 minutes. After filtration, the filtrate is concentrated to 1 / 3 of its volume. Two times the volume of 95% ethanol is added to the filtrate, and the mixture is allowed to stand at 4°C for 1 hour. The mixture is then centrifuged at 4500 r / min for 5 minutes. The collected precipitate is dried at 60°C for 6-8 hours to obtain the polysaccharide extract from *Clerodendrum tigrinum*.

4. The method for preparing the *Clerodendrum trichotomum* polysaccharide-whey protein isolate composite gel according to claim 1, characterized in that, In step (2), the preparation of the *Clerodendrum trichotomum* polysaccharide stock solution is as follows: *Clerodendrum trichotomum* polysaccharide extract is dissolved in ultrapure water to prepare *Clerodendrum trichotomum* polysaccharide solutions with mass fractions of 2.0%, 3%, 4%, and 5.0%, respectively. The solutions are then placed at 25°C and magnetically stirred at 500 r / min for 1 hour and then placed at 4°C overnight to obtain *Clerodendrum trichotomum* polysaccharide stock solutions with mass fractions of 2.0%, 3%, 4%, and 5.0%.

5. The method for preparing the *Clerodendrum trichotomum* polysaccharide-whey protein isolate composite gel according to claim 1, characterized in that, In step (3), the whey protein isolate solution is prepared by dissolving whey protein isolate in ultrapure water to prepare a whey protein isolate solution with a mass fraction of 25%. The solution is then placed at 25°C and magnetically stirred at 500 r / min for 1 hour, and then placed at 4°C overnight to dissolve the protein fully, thus obtaining the whey protein isolate solution.

6. The method for preparing the *Clerodendrum trichotomum* polysaccharide-whey protein isolate composite gel according to claim 1, characterized in that, In step (4), the preparation of the *Clerodendrum trichotomum* polysaccharide-whey protein isolate mixture is as follows: Take the 2.0%, 3%, 4%, and 5.0%d *Clerodendrum trichotomum* polysaccharide stock solutions from step (2) and the whey protein isolate solution from step (3) at a volume ratio of 1:0.5-1.

5. Place them in a magnetic stirring system at a temperature of 21-35℃ and a rotation speed of 180-450r / min for 22-45 minutes until uniform. Then adjust the pH to 5.0-8.0 to obtain the *Clerodendrum trichotomum* polysaccharide-whey protein isolate mixture with polysaccharide concentrations of 1.0%, 1.5%, 2.0%, and 2.5%, respectively.

7. The method for preparing the *Clerodendrum trichotomum* polysaccharide-whey protein isolate composite gel according to claim 6, characterized in that, In step (4), the preparation of the *Clerodendrum trichotomum* polysaccharide-whey protein isolate mixture is as follows: Take the 2.0%, 3%, 4%, and 5.0%d *Clerodendrum trichotomum* polysaccharide stock solutions from step (2) and mix them with the whey protein isolate solution from step (3) at a volume ratio of 1:

1. Place them in a magnetic stirring system at 25°C and 300r / min for 30 minutes until homogeneous. Then adjust the pH to 7.0 to obtain the *Clerodendrum trichotomum* polysaccharide-whey protein isolate mixture with polysaccharide concentrations of 1.0%, 1.5%, 2.0%, and 2.5%, respectively.

8. The method for preparing the *Clerodendrum trichotomum* polysaccharide-whey protein isolate composite gel according to claim 1, characterized in that, In step (5), thermal gelation is performed by placing the 1.0%, 1.5%, 2.0%, and 2.5% polysaccharide-whey protein isolate mixtures from step (4) in a water bath at 85-110°C for 22-43 minutes, followed by cooling in an ice water bath to room temperature, sealing, and refrigerating at 3-6°C overnight to obtain polysaccharide-whey protein isolate composite gels with polysaccharide concentrations of 1.0%, 1.5%, 2.0%, and 2.5%.

9. The method for preparing the *Clerodendrum trichotomum* polysaccharide-whey protein isolate composite gel according to claim 8, characterized in that, In step (5), thermal gelation is performed by placing the 1.0%, 1.5%, 2.0%, and 2.5% polysaccharide-whey protein isolate mixtures from step (4) into a 95°C water bath and heating for 30 minutes, followed by cooling to room temperature in an ice water bath, sealing, and refrigerating at 4°C overnight to obtain polysaccharide-whey protein isolate composite gels with polysaccharide concentrations of 1.0%, 1.5%, 2.0%, and 2.5%.

10. The application of a polysaccharide-whey protein isolate composite gel from *Clerodendrum trichotomum* in the preparation of a food processing gel matrix, characterized in that... When the food is yogurt or jelly, the composite gel is used to improve the stability, water retention and mouthfeel of the yogurt or jelly.

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