Preparation method and application of vegetable protein-pectin particle stable composite emulsion

Abstract

The invention discloses a preparation method and application of a vegetable protein-pectin particle stable composite emulsion, and belongs to the technical field of vegetable protein emulsion preparation. The preparation method comprises the following steps: mixing thermally induced peanut protein particles with pectin, and carrying out high-speed shearing emulsification to construct the oil-in-water peanut protein-pectin composite emulsion. The composite emulsion disclosed by the invention is controllable and stable in structure and enhanced in function, and has a wide application prospect in the field of foods such as dairy products.

Description

Technical Field

[0001] This invention belongs to the field of plant protein emulsion preparation technology, specifically relating to a stable composite emulsion constructed using pectin and peanut protein, and its application in the food industry. Background Technology

[0002] Peanuts, as one of the world's most important oilseed crops, are rich in nutrients such as protein, dietary fiber, unsaturated fatty acids, carbohydrates, fortified vitamins, and minerals. Peanut protein (PPI), a major byproduct of peanut oil extraction, contains a large amount of essential amino acids and has extremely high nutritional value. Due to its ease of extraction, non-irritating nature, high bioavailability, easy digestibility in the gastrointestinal tract, and high net protein utilization rate, as well as its excellent solubility, water-holding capacity, viscosity, gelling properties, and emulsifying properties, peanut protein is considered a high-quality protein in the food industry.

[0003] Pectin is a heteropolysaccharide rich in galacturonic acid, found in the cell walls of higher plants. It can lower blood lipids, relieve pain, reduce the risk of heart disease, block lipase activity, and induce apoptosis in cancer cells. Pectin is a structurally and biocompatible polysaccharide, primarily found in the primary and middle layers of plant cell walls. It mainly supports tissue structure and rigidity, promoting plant swelling, mechanical resistance, and intercellular adhesion. Pectin has various medical applications and is highly valued as a functional food ingredient. Furthermore, pectin enhances the taste and texture of its derivative foods and significantly promotes plant growth and development by acting as a barrier against external factors and providing mechanical resistance. Pectin can be classified into low-methoxyl pectin (LMP, DE < 50%) and high-methoxyl pectin (HMP, DE ≥ 50%).

[0004] An emulsion system is a droplet dispersion system formed by two immiscible liquids (such as oil / water) under the action of an emulsifier. Polysaccharides and proteins, as natural biomolecules, can synergistically construct various types of emulsions, and their interactions can enhance emulsion stability. Peanut protein, being a biomacromolecule, results in protein emulsions with relatively large droplet sizes, making them prone to instability due to droplet aggregation, flocculation, and Austronesian ripening, thus making it difficult to form a stable system that meets requirements in actual production. Summary of the Invention

[0005] To address the stability issue of peanut protein emulsions, the inventors have provided a method for constructing structurally controllable and functionally enhanced composite submicron / micron emulsions using pectin and peanut protein. The technical solution is as follows:

[0006] A method for preparing a plant protein-pectin microparticle-stabilized composite emulsion, wherein the preparation method involves mixing thermally induced peanut protein particles (90–95℃, cooling, centrifugation to remove large aggregates) with pectin, followed by high-speed shear emulsification to construct an oil-in-water peanut protein-pectin composite emulsion.

[0007] The specific steps are as follows:

[0008] (1) Preparation of peanut protein particles: Dissolve peanut protein (PPI) in water at a concentration of 3-5%, stir at 25±0.5℃ for 8-15 minutes, and adjust the pH to 7.0±0.1 with 0.05-0.15 mM HCl; heat the solution at 90-95℃ for 25-45 minutes, and then cool at 2-8℃ for 10-15 hours to obtain peanut protein gel particles; centrifuge the gel particles at 3000-5000 rpm at 25±0.5℃ for 8-12 minutes to remove large aggregates, and then dilute with deionized water to a concentration of 1.5-2.5% peanut protein gel particle dispersion. The above percentages are mass-volume percentages.

[0009] (2) Preparation of composite emulsion: Dissolve 0.1%-1% w / v high ester pectin (HMP) or low ester pectin (LMP) in water, stir at 25±0.5℃ for 8-15 minutes, then heat at 50-70℃ for 0.5-1.5 hours, and cool to room temperature before use; mix the diluted peanut protein gel particle dispersion with the pectin solution and stir at 25±0.5℃ for 8-15 minutes to obtain peanut protein-pectin dispersion; use this dispersion as the aqueous phase, mix with corn oil, and shear at 11,000-13,000 rpm for 1-3 minutes at 25±0.5℃ to obtain oil-in-water peanut protein-high ester pectin (PPI-HMP) composite emulsion or peanut protein-low ester pectin (PPI-LMP) composite emulsion.

[0010] Furthermore, the volume ratio of the peanut protein gel particle dispersion to the pectin solution is (1-2):1.

[0011] Furthermore, the volume ratio of the aqueous phase to the oil phase is (6-8):3.

[0012] Furthermore, the pectin is preferably 1% high-ester pectin.

[0013] Furthermore, the droplet size of the composite emulsion is 10–100 μm.

[0014] Furthermore, the application of the protein-pectin microparticle-stabilized composite emulsion in dairy products involves mixing effective components such as DHA / EPA, MCT, phytosterols, carotenoids, and vitamins A / D / E / K with the PPI-HMP composite emulsion, and then adding it to dairy beverages. The composite emulsion allows these effective components to be stably dispersed in the dairy beverage, reducing oxidation and preventing floating. By forming a submicron / micron oil droplet outer layer encapsulating the particle interface, it offers advantages such as resistance to fat floating, resistance to thermal shock, and improved shelf-life stability.

[0015] Furthermore, the application of the protein-pectin microparticle-stabilized composite emulsion in plant-based beverages.

[0016] Furthermore, the application of the protein-pectin microparticle-stabilized composite emulsion in functional foods.

[0017] Furthermore, the application of the protein-pectin microparticle-stabilized composite emulsion in oil-soluble active ingredient carriers.

[0018] The advantages of the above technical solution, which differs from existing technologies, are as follows:

[0019] (1) Plant proteins provide interfacial activity and film-forming ability, and combined with the charge and steric hindrance provided by pectin, a certain water retention and thickening effect is achieved; after the two form microparticles, the interfacial layer is thicker, the drainage is slower, and the oil droplets are less likely to clump together.

[0020] (2) A compound emulsion can be added before or after fermentation to serve as an "oil-soluble flavor / active substance delivery carrier" to achieve more controllable release, and to maintain the stability of oil droplets and improve texture during the pH drop and milk protein gel formation process.

[0021] (3) By adjusting the appropriate protein: pectin ratio, heat treatment, cross-linking method, etc., the microparticles form a stronger interface layer, and control the total solids and homogenization conditions of the system, the adsorption and competition between the existing natural fat globule membrane (MFGM) and casein micelles in the milk system, plus the submicron / micron oil droplets. Attached Figure Description

[0022] Figure 1 Images of different concentrations of PPI-LMP / HMP emulsions described in the specific embodiments under a laser confocal microscope.

[0023] Figure 2 The particle size distribution of PPI-LMP / HMP emulsions with different concentrations as described in the specific embodiments.

[0024] Figure 3 The near-infrared transmission spectra of PPI-LMP / HMP emulsions with different concentrations as described in the specific embodiments are shown.

[0025] Figure 4 The clarification index refers to the different concentrations of PPI-LMP / HMP emulsions described in the specific embodiments.

[0026] Figure 5 The water contact angle of the different concentrations of PPI-LMP / HMP emulsions described in the specific implementation method changes at 0s and 60s.

[0027] Figure 6 The frequency sweep test of PPI-LMP / HMP emulsions with different concentrations is described in the specific implementation method.

[0028] Figure 7 The creep and recovery tests of PPI-LMP / HMP emulsions with different concentrations are described in the specific implementation method.

[0029] Figure 8 Steady-state shear tests on PPI-LMP / HMP emulsions of different concentrations, as described in the specific implementation method.

[0030] Figure 9 The three-stage thixotropic test of PPI-LMP / HMP emulsions with different concentrations is described in the specific implementation method.

[0031] Figure 10 The strain scanning test of PPI-LMP / HMP emulsions with different concentrations is described in the specific implementation method.

[0032] Figure 11 The relationship between the loss tangent and strain of PPI-LMP / HMP emulsions of different concentrations described in the specific embodiments.

[0033] Figure 12 The Fourier transform intensity ratio of different concentrations of PPI-LMP / HMP emulsions described in the specific implementation method.

[0034] Figure 13 The elastic Lissajous stress-strain curves of PPI-LMP emulsions with different concentrations at different strain amplitudes and LMP concentrations, as described in the specific implementation method.

[0035] Figure 14 The elastic Lissajous stress-strain curves of PPI-HMP emulsions with different concentrations at different strain amplitudes and LMP concentrations, as described in the specific implementation method.

[0036] Figure 15 The strain function represents the hardening index (S) and shear thickening / thinning index (T) of the PPI-LMP / HMP emulsions with different concentrations described in the specific embodiments. Detailed Implementation

[0037] To explain in detail the technical content, structural features, objectives, and effects of the technical solution, the following description is provided in conjunction with specific embodiments and accompanying drawings.

[0038] Example 1

[0039] 1 Experimental Methods

[0040] 1.1 Preparation of peanut protein particles

[0041] Dissolve PPI in water at a concentration of 4% w / v and stir at room temperature (25 ± 0.5 °C) for 10 minutes. Adjust the pH to 7.0 with 0.1 mM HCl. Heat the solution at 95 °C for 30 minutes, then cool at 4 °C for 12 hours to obtain the PPI solution. Centrifuge the solution at 4000 rpm for 10 minutes at 25 °C to remove large aggregates, and then dilute with deionized water to a concentration of 2% w / v.

[0042] 1.2 Preparation of PPI-HMP / LMP

[0043] First, 2% w / v high-ester pectin (HMP) or low-ester pectin (LMP) was dissolved in water and stirred for 10 minutes at room temperature (25±0.5℃). Then, it was heated at 60℃ for 1 hour and cooled to room temperature before use. Pectin solutions with concentrations of 0.1%, 0.2%, 0.4%, 0.6%, 0.8%, and 1% w / v were prepared. Next, peanut protein was mixed with these pectin solutions (2% PPI, 0.1%-1% pectin) in a 1:1 ratio and stirred for 10 minutes at room temperature (25±0.5℃) to obtain a PPI-polysaccharide dispersion. Finally, this dispersion was used as the aqueous phase and mixed with corn oil (water to oil volume ratio 7:3). The mixture was then homogenized using a high-speed homogenizer at 12,000 rpm for 2 minutes at room temperature (25±0.5℃) to obtain oil-in-water (W / O) PPI-HMP or PPI-LMP.

[0044] 1.3 Basic Physicochemical Characteristics

[0045] 1.3.1 Microstructure Observation

[0046] The microstructure of PPI-HMP or PPI-LMP was observed using a laser confocal microscope (Carl Zeiss, LSM 880, Germany). PPI-HMP or PPI-LMP (10 μL) stained with Nile Red and Nile Blue (0.1% w / v) were observed at excitation wavelengths of 433 nm and 688 nm, and images were taken under 20x and 63x oil immersion lenses.

[0047] 1.3.2 Particle size and particle size distribution

[0048] The droplet size of each sample was measured using a laser particle size analyzer (Mastersizer 3000, Malvern, UK) with refractive indices of 1.52 for emulsions and 1.33 for water to obtain the D4,3 diameter and droplet size distribution.

[0049] 1.3.3 Centrifugal stability

[0050] The centrifugal stability of fresh emulsion was analyzed using a LUMiSizer (LUM, Germany) full-function stability analyzer. 420 μL of emulsion was placed in a measuring tube and centrifuged at 4000 rpm / min, 25°C, and 865 nm light for 1 hour.

[0051] 1.4 Contact Angle and Interfacial Tension

[0052] The surface hydrophobicity of peanut protein pectin composite particles was measured using an optical contact angle meter (OCA 25). The particles were pressed into 0.2 mm thin sheets using a tablet press and then immersed in corn oil. Subsequently, 0.5 μL of water was injected onto the thin sheets, and the contact angle values ​​at 0 s and 60 s were recorded using a high-speed camera. The contact angle was calculated according to the Young-Laplace equation.

[0053] The adsorption tension of peanut protein pectin composite particles at the interface over time was tested using OCA 25. The test employed a suspended drop method with a volume of 20 μL. The adsorption process was measured over 6000 s using a video image acquisition device, and the results were calculated according to the Young-Laplace equation, as shown in the following formula:

[0054] (1)

[0055] (2)

[0056] In the formula, σ is the interfacial tension, ∆ρ is the density difference between the sample solution and the oil phase, g is the gravitational acceleration constant, C is the capillary constant, b is the radius of curvature of the droplet apex, x is the abscissa of any point on the outer contour plane of the droplet, z is the relative ordinate, and θ is the tangential angle of any point.

[0057] 1.5 Rheological characteristics

[0058] 1.5.1 Small Amplitude Oscillation Shear (SAOS)

[0059] SAOS measurements were performed on a parallel plate geometry (40 mm in diameter, 1000 μm gap) at 25 °C using a TA Instruments Discovery HR-10 rheometer.

[0060] 1.5.1.1 Frequency Sweep Test

[0061] Frequency sweep measurements were performed within the angular frequency range of 0.1–100 rad / s at 0.1% strain (within LVR). In LVR, the oscillating stress response can be described by equation (3):

[0062] (3)

[0063] In the formula: ω is the angular frequency, t is time, γ is strain, and σ' and σ'' are the elastic and viscous stress components, respectively.

[0064] To describe the dependence of the modulus on frequency, the energy storage modulus G' and the loss modulus G'' are modeled using a power law (Equations 4 and 5):

[0065] (4)

[0066] (5)

[0067] In the formula: and They are and The intercept, and These are dimensionless indices that reflect the frequency dependence of elasticity and viscosity moduli.

[0068] 1.5.1.2 Creep and Recovery Tests

[0069] The creep test is performed by applying a constant stress of 1 Pa (within LVR) for 5 min, then immediately removing the stress and observing the strain recovery for 5 min.

[0070] 1.5.1.3 Steady-state shear

[0071] At 25°C, the measurement was performed from 1 second... -1 up to 100 s -1 The apparent viscosity at the shear rate was determined, and the flow curve was obtained.

[0072] 1.5.1.4 Three-stage thixotropic test (3ITT)

[0073] Thixotropy was evaluated using a three-stage thixotropic test. The low shear rate for the first and third stages was 1.0 s⁻¹. -1 The high shear rate of the second segment is 100 s. -1 The high shear rate was assessed by using a 25°C (low-high-low) temperature, with each interval lasting 180 s, to evaluate the structural disruption and reconstruction capabilities of the microgels. The tests were based on those conducted by Kim et al.

[15] The method was slightly modified.

[0074] 1.5.2 Large Amplitude Oscillation Shear (LAOS)

[0075] LAOS used a TA Instruments Discovery HR-20 rheometer on parallel plates (40 mm in diameter, 1000 μm in gap) at 25°C to evaluate nonlinear viscoelastic behavior.

[0076] 1.5.2.1 Strain scanning test

[0077] Strain scanning tests were performed at a fixed frequency of 1 Hz and 25 °C, with strain amplitudes ranging from 0.1% to 1000%.

[0078] 1.5.2.2 Fourier Transform Analysis

[0079] The full spectrum of the nonlinear stress response was obtained using Fourier transform analysis. During the test, the waveform was decomposed into several odd harmonics (I1, I3, I5, ...), and the intensity of the odd harmonics characterizes the nonlinear behavior of LAOS. The time-domain stress signal was decomposed into frequency-domain components to quantify the nonlinear response. The intensity ratio of higher harmonics was used to quantify the degree of nonlinearity down to the fundamental frequency (Equation 6), where a larger ratio indicates a greater degree of nonlinearity.

[0080] (6)

[0081] 1.5.2.3 Lissajous Curve

[0082] The material response is characterized using stress-strain (elastic) and stress-strain rate (viscous) curves. The area enclosed by the loop of the elastic curve is proportional to the energy consumed per cycle; a larger loop area indicates more energy consumption, as given by equation (7):

[0083] (7)

[0084] Among them, E d It is the energy consumption per unit volume in a single cycle, π is the perimeter ratio, γ0 is the strain amplitude, and G1" is the loss modulus.

[0085] 1.5.2.4 Chebyshev Curve

[0086] The stress response is decomposed into elastic and viscous components using the Chebyshev polynomial. For the elastic Lissajous curve:

[0087] … (8)

[0088] … (9)

[0089] Where Emax and Emin are the elastic moduli at the maximum and minimum strains, respectively.

[0090] Similarly, for the viscous Lissajous curve:

[0091] … (10)

[0092] … (11)

[0093] Where Vmax and Vmin are the viscous moduli at the maximum and minimum shear rates, respectively.

[0094] The strain hardening exponent (S) and the shear thickening / thinning exponent (T) are two parameters derived from the Lissajous curves quantifying the nonlinear behavior under LAOS conditions. The strain hardening exponent S and the shear thinning exponent T are defined by formulas (12) and (13).

[0095] (12)

[0096] (13)

[0097] Where S is the strain hardening exponent, G'L is the secant modulus (maximum strain modulus when γ is at its maximum value), and G'M is the shear modulus (minimum decomposable strain modulus when γ=0). T is the shear thickening / thinning exponent, η′L is the dynamic viscosity at the maximum additional shear rate, and η′M is the dynamic viscosity at the minimum decomposable strain rate.

[0098] 2 Results and Analysis

[0099] 2.1 Microstructure

[0100] The appearance of PPI-LMP / HMP emulsion droplets was observed under a laser confocal microscope. Microscopic images are shown below. Figure 1 As shown, with the increase of HMP / LMP concentration in the aqueous phase, the average diameter of the droplets decreased significantly, their number increased, their distribution became more uniform, and aggregation was reduced. This may be because the addition of LMP / HMP enhanced the electrostatic repulsion and spatial stability between particles. Compared with PPI-LMP, the phenomenon was more pronounced in the emulsion droplets with added HMP as the concentration increased. Simultaneously, all emulsion droplets exhibited a clear spherical shape, indicating that the LMP / HMP absorbed at the oil-water interface acted as a physical barrier to prevent oil aggregation.

[0101] 2.2 Particle size and particle size distribution

[0102] like Figure 2As shown, the particle size of PPI-LMP / HMP varies significantly with different concentrations. The average droplet size D4.3 decreases with increasing concentration, with the smallest particle size observed at a concentration of 1.0%, indicating that the complex exhibits optimal emulsification efficiency at this concentration. The particle size distribution is generally within 10... 1 ~10 2 Within the μm range. This is consistent with images captured by laser confocal imaging.

[0103] 2.3 Centrifugal stability

[0104] The stability of the PPI-LMP / HMP emulsion under centrifugation was studied using a stability analyzer. Figure 3 As shown, the stability of the emulsion after centrifugation was evaluated using transmittance profile analysis. The horizontal axis represents the position of the liquid sample relative to the bottom, and the vertical axis corresponds to the transmittance of the sample. The increase in signal in the red area generally corresponds to the floating of the oil phase (increased transmittance in the oil-rich area), while changes in the green area are related to the sedimentation or clarification of the aqueous phase. After centrifugation, the transmittance of all samples increased significantly at both the bottom and top of the tube, confirming oil-water separation. However, the degree of separation varied significantly among different samples: the transmittance curves of emulsions with different concentrations of HMP showed relatively small changes, indicating that HMP inhibited phase separation to some extent; while the transmittance of emulsions with added LMP systematically decreased with increasing LMP concentration, indicating that LMP is more effective in resisting centrifugation-induced instability, and its stabilizing effect is concentration-dependent—the higher the concentration, the better the overall stability of the emulsion.

[0105] Clarification Index ( Figure 4 The clarification index reflects the instability of the emulsion. A higher index indicates more severe oil-water separation, while a lower index indicates a more stable system with stronger resistance to stratification. The results showed that as the LMP concentration increased from 0.1% to 1.0%, the clarification index first decreased and then slightly increased, reaching its lowest value at a concentration of approximately 0.4%. This trend is consistent with centrifugal stability (…). Figure 3 ) and particle size analysis ( Figure 2 The results corroborate each other: an appropriate amount of LMP (such as 0.4%) can form the optimal composite interface structure with PPI, producing fine and uniform droplets, thereby delaying phase separation to the greatest extent; while when the concentration is too high, it may have a slight adverse effect due to the excessive viscosity of the system or the strong intermolecular interaction.

[0106] 2.4 Surface hydrophobicity

[0107] Figure 5The contact angle values ​​recorded by the high-speed camera at 0 s and 60 s are displayed, and the contact angle figures were calculated according to the Young-Laplace equation to reflect the hydrophobicity of the PPI-LMP / HMP composite surface. When θ < 90°, it indicates hydrophilicity; when θ > 90°, it indicates hydrophobicity. At 0 s, as the LMP content increased to 1.0%, the contact angle decreased from 121.3° to 106.15°, indicating a decrease in surface hydrophobicity and an increase in hydrophilicity. As time progressed to 60 s, the contact angle decreased significantly further, from 95.8° to 51.8°, indicating a substantial increase in hydrophilicity. At an LMP content of 1.0%, the contact angle was the smallest at 60 s, indicating the strongest hydrophilicity and best wettability. Compared to LMP-PPI, the HMP-added complex showed a decrease in contact angle from 117.45° to 111.35° at 0 s, while exhibiting the lowest contact angle and strongest hydrophilicity at a concentration of 0.8% at 60 s. Overall, the HMP complex exhibited stronger surface hydrophobicity and poorer wettability, which may be attributed to the high degree of methylation of HMP itself, resulting in high hydrophobicity.

[0108] 2.5 Small Amplitude Oscillation Shear (SAOS)

[0109] Figure 6 Frequency sweep experiments showed that PPI-LMP / HMP emulsions of different concentrations exhibited significant solid-like behavior. Their storage modulus G' remained higher than the loss modulus G'' throughout the entire frequency range, indicating an elastic state. Furthermore, the curves for both were relatively smooth and showed weak frequency dependence, suggesting the formation of a stable three-dimensional network structure within the emulsion. With increasing concentration, the curves for G' and G'' shifted significantly towards higher modulus values, indicating a significant enhancement in viscoelasticity. This confirms that concentration is the decisive factor in regulating the rheological properties of this emulsion system; higher concentrations provide more molecular cross-linking points, thereby constructing a more robust elastic network.

[0110] creep curve ( Figure 7 The curves demonstrate the deformation of PPI-LMP / HMP emulsions under constant stress and their recovery ability after stress removal. The curves show that the PPI-LMP emulsion behaves as a near-perfect elastic solid, possessing extremely high rigidity and complete recoverability, with rigidity increasing with concentration. In contrast, the PPI-HMP emulsion exhibits significant viscoelastic fluid behavior, with large instantaneous deformation, continuous flow, and irrecoverable permanent deformation, and its viscous characteristics intensify with increasing concentration.

[0111] Steady-state shear test ( Figure 8The apparent viscosity of the PPI-LMP / HMP emulsion during flow was shown. With increasing shear rate, the apparent viscosity of PPI-LMP / HMP emulsions at different concentrations gradually decreased, while the shear stress gradually increased across the entire shear rate range. All samples exhibited shear-thinning behavior. The LMP system exhibited high viscosity and structural stability, while the HMP system showed significant shear-thinning. Both were positively modulated by concentration.

[0112] according to Figure 9 The results of the three-stage thixotropic test show that the PPI-LMP emulsion can quickly recover its viscosity and structure after shear failure, exhibiting excellent thixotropic reversibility. In contrast, under the same conditions, the recovery curve of the PPI-HMP emulsion after failure is flat and rises slowly, and the final recovered viscosity value is lower than the initial value, indicating that irreversible collapse occurred in the high shear part, resulting in significant and persistent viscosity loss.

[0113] In summary, LMP-PPI forms a strong and highly reversible elastic gel network, exhibiting high modulus, complete creep recovery, weak shear thinning, and excellent thixotropic structural recovery. HMP-PPI, on the other hand, forms a fragile and irreversible viscous network, exhibiting low modulus, permanent creep deformation, significant shear thinning, and poor thixotropic recovery. Concentration can significantly modulate the strength performance of both systems, and the pectin type (LMP and HMP) is likely a key factor determining network elasticity and structural reversibility.

[0114] 2.6 Large Amplitude Oscillation Shear (LAOS)

[0115] according to Figure 10 Strain scanning results of PPI-LMP emulsions at different concentrations showed that all samples exhibited stable solid-state gel properties in the low-strain region (G'>G''). With increasing strain, G' gradually decreased and eventually intersected with G'', indicating that the gel network yielded and broke down. Higher concentrations resulted in a wider linear viscoelastic region, a larger critical yield strain, and a significantly increased absolute value of the storage modulus G' across the entire strain range. This demonstrates that the gel network formed by LMP-PPI exhibits a clear strain dependence, and its structural stability and resistance to deformation failure significantly increase with increasing concentration. Similarly, increasing LMP concentration and oil content both enhance network connectivity, thereby increasing the elastic properties of the emulsion.

[0116] Figure 11The relationship between the loss tangent and strain is shown. Tanδ is the ratio of loss modulus to storage modulus (tanδ = G′′ / G′), reflecting the transition of the sample from a liquid to a solid-like state. Tanδ increases with increasing strain in all systems, indicating that the structure yields from an elastic solid to a viscous liquid. However, the PPI-LMP system (especially at high concentrations) exhibits a lower initial tanδ value and a higher critical yield strain, confirming the formation of a highly elastic, deformation-resistant gel network. Conversely, the PPI-HMP system has a higher initial tanδ value and increases more rapidly, indicating a fragile structure that is sensitive to shear.

[0117] Figure 12 Fourier transform intensity analysis was performed, with an intensity ratio of I5 / I3. Data shows that as the LMP concentration increases from 0.1% to 1.0%, the I5 / I3 curve shifts significantly downward, and the peak value decreases, indicating that the higher-order, more severe nonlinear response of the high-concentration network is suppressed during deformation. This suggests that the failure mechanism shifts from localized, severe fracture at low concentrations to a more uniform and gentler softening. With increasing HMP concentration, the decrease in I5 / I3 value is limited or insignificant. A high I5 / I3 value implies the generation of strong higher-order nonlinear harmonics during yielding, a sign of localized stress concentration and severe, irreversible slippage or fracture of the microstructure. This demonstrates that the weak interaction between HMP and PPI cannot construct a uniform, coherent network; its structure is prone to concentrated collapse at weak points during deformation, resulting in a severe and irreversible failure process.

[0118] Figure 13 and Figure 14 Elastic Lissajous curves are shown for different strain amplitudes and LMP / HMP concentrations. The Lissajous curves show that the emulsion strain amplitude is 0.1% and remains elliptical, indicating that its linear viscoelastic response has a significant ability to store elastic energy. Figure 12 The stress-strain curves show that the network structure of the PPI-LMP gel is significantly enhanced with increasing LMP concentration. The curves of low-concentration samples are flat, suggesting that the network is prone to irreversible deformation; while high-concentration samples (e.g., 1.0%) exhibit full, closed elliptical shapes, proving that they form a robust and highly reversible elastic network.

[0119] Figure 14 The stress-strain Lissajous figures show that the PPI-HMP composite system exhibits highly distorted and severely flattened irregular curves under high strain, in stark contrast to the full elliptical structure of the PPI-LMP system. This shape indicates that the network structure constructed by the weak interaction between HMP and PPI is loose and non-uniform, and irreversible yielding, fracture, and energy dissipation occur at strains far lower than those of the LMP system, demonstrating extremely poor nonlinear elasticity and structural resilience.

[0120] Figure 15 The rheological analysis quantitatively revealed the decisive regulatory role of LMP concentration on the mechanical properties of the composite gel network. Data showed a direct positive correlation between LMP concentration and network strength: as the concentration increased from 0.1% to 1.0%, the elastic response at 800% strain increased by approximately 80%, directly confirming that high-concentration LMP enhances the electrostatic crosslinking density, constructing a three-dimensional network with significantly improved rigidity. Simultaneously, all systems exhibited strong elastic behavior (G′ > G′′) with extremely low viscous dissipation, demonstrating the high reversibility of network failure.

[0121] 3. Conclusion

[0122] PPI-HMP exhibits stronger surface hydrophobicity, which can more effectively reduce interfacial tension and form finer and more uniform initial emulsion droplets; while PPI-LMP constructs a robust three-dimensional gel network through strong electrostatic interactions. This network endows the emulsion with excellent viscoelasticity, resistance to centrifugal instability, and thixotropic recovery, thereby achieving superior long-term physical stability.

[0123] Example 2

[0124] Milk beverages / yogurt / fermented milk: Adding effective ingredients such as DHA / EPA, MCT, fat-soluble vitamins (A / D / E / K), and carotenoids to milk beverages / yogurt / fermented milk with PPI-HMP complex emulsion can make the effective ingredients more stable and reduce floating and layering, oil rings, and oxidative odors.

[0125] Example 3

[0126] Plant-based beverages (oat / soy milk, etc.): PPI-HMP complex emulsion concentrate is added to oat beverage or soy milk base, premixed with low shear, and then subjected to conventional homogenization and heat treatment to obtain stable plant-based beverages with little or no synthetic emulsifiers, thereby improving beverage stability.

[0127] Example 4

[0128] Functional beverages: PPI-HMP complex emulsion concentrate is added to an electrolyte / vitamin functional beverage base, and then premixed, homogenized and heat-treated to obtain ready-to-drink products.

[0129] Nutritional powder preparation: PPI-HMP complex emulsion concentrate is mixed with an edible carrier (such as maltodextrin) and then pulverized to obtain an oil-containing active instant powder. This powder is then compounded with protein powder / mineral powder to form a reconstituted nutritional powder. After reconstitution with a fixed powder-to-water ratio and shaking time, the reconstitution stability and anti-stratification ability are improved.

[0130] Example 5

[0131] Delivery of oil-soluble flavor / active compounds via PPI-HMP composite emulsion in fermented milk: A PPI particle dispersion and HMP solution were prepared according to the method in Example 1 and mixed to form a PPI-HMP composite aqueous phase. Fish oil, krill oil, or an oil phase containing dissolved coenzyme Q10, lutein, curcumin, etc., were added to the composite aqueous phase and emulsified to obtain a concentrated PPI-HMP composite emulsion. The composite emulsion was added to a milk base and thoroughly mixed, then subjected to heat treatment, homogenization, inoculation, and fermentation according to conventional processes to obtain fermented milk. The PPI-HMP composite emulsion serves as a carrier for oil-soluble flavor / active compounds, enabling more controllable release of flavor / active compounds before and after fermentation. Furthermore, it maintains oil droplet stability during the pH decrease and milk protein gel formation stages of fermentation, reducing stratification and whey precipitation, and improving the viscoelasticity and texture of the system.

[0132] It should be noted that although the above embodiments have been described herein, this does not limit the scope of patent protection of the present invention. Therefore, any changes and modifications made to the embodiments described herein based on the innovative concept of the present invention, or equivalent structural or procedural transformations made using the content of the present invention's specification and drawings, directly or indirectly applying the above technical solutions to other related technical fields, are all included within the scope of patent protection of the present invention.

Claims

1. A method for preparing a plant protein-pectin microparticle-stabilized composite emulsion, characterized in that, The preparation method involves mixing thermally induced peanut protein particles with pectin, followed by high-speed shear emulsification to construct an oil-in-water peanut protein-pectin composite emulsion.

2. The method for preparing the plant protein-pectin microparticle-stabilized composite emulsion according to claim 1, characterized in that, The specific steps are as follows: Preparation of peanut protein particles: Dissolve peanut protein in water at a concentration of 3-5%, stir at 25±0.5℃ for 8-15 minutes, and adjust the pH to 7.0±0.1 with 0.05-0.15 mM HCl; heat the solution at 90-95℃ for 25-45 minutes, and then cool at 2-8℃ for 10-15 hours to obtain peanut protein gel particles; centrifuge the solution at 3000-5000 rpm for 8-12 minutes at 25±0.5℃, and then dilute with deionized water to a concentration of 1.5-2.5% peanut protein gel particle dispersion; Preparation of the composite emulsion: Dissolve 0.1%-1% of high-ester pectin or low-ester pectin in water, stir at 25±0.5℃ for 8-15 minutes, then heat at 50-70℃ for 0.5-1.5 hours, and cool to room temperature before use; mix the diluted peanut protein gel particle dispersion with the pectin solution, and stir at 25±0.5℃ for 8-15 minutes to obtain a peanut protein-pectin dispersion; use this dispersion as the aqueous phase, mix with corn oil, and shear at 11,000-13,000 rpm for 1-3 minutes at 25±0.5℃ to obtain an oil-in-water peanut protein-high-ester pectin composite emulsion or a peanut protein-low-ester pectin composite emulsion. The above percentages are mass-volume percentages.

3. The method for preparing the plant protein-pectin microparticle-stabilized composite emulsion according to claim 2, characterized in that, The volume ratio of the peanut protein gel particle dispersion to the pectin solution is (1-2):

1.

4. The method for preparing the plant protein-pectin microparticle-stabilized composite emulsion according to claim 2, characterized in that, The volume ratio of the aqueous phase to the oil phase is (6-8):

3.

5. The method for preparing the plant protein-pectin microparticle-stabilized composite emulsion according to claim 2, characterized in that, The pectin is preferably 1% high-ester pectin.

6. The method for preparing the plant protein-pectin microparticle-stabilized composite emulsion according to claim 2, characterized in that, The droplet size of the composite emulsion is 10–100 μm.

7. The application of a plant protein-pectin microparticle-stabilized composite emulsion as described in any one of claims 1-6 in dairy products.

8. The application of a plant protein-pectin microparticle-stabilized composite emulsion as described in any one of claims 1-6 in plant-based beverages.

9. The application of a plant protein-pectin microparticle-stabilized composite emulsion as described in any one of claims 1-6 in functional foods.

10. The application of a plant protein-pectin microparticle-stabilized composite emulsion as described in any one of claims 1-6 in an oil-soluble active ingredient carrier.

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