Preparation process of epicatechin bridged double protein eugenol microcapsule

Abstract

This invention relates to the field of eugenol microcapsule preparation technology, and discloses a preparation process for epicatechin-bridged dual-protein eugenol microcapsules, comprising: S1, dissolving zein, eugenol and epicatechin in 70%-80% ethanol and stirring to obtain an organic phase; S2, dissolving whey protein in water to prepare a 0.5%-2% solution and adjusting the pH to 6.5-7.5 to obtain an aqueous phase; S3, rapidly injecting the organic phase into the aqueous phase with stirring at a volume ratio of 1:8-1:12, and stirring until the nanoparticles are stable to obtain a suspension; S4, removing the ethanol from the suspension by rotary evaporation to obtain a concentrated solution; S5, aging the concentrated solution at 4-8℃ for 12-24 hours, and then freezing or spray drying to obtain microcapsule powder. This invention utilizes epicatechin as a natural molecular bridge to bridge hydrophilic whey protein and hydrophobic zein, forming a three-dimensional network wall material. This provides a stable encapsulation space for eugenol, significantly improving the encapsulation rate compared to systems without epicatechin. This invention solves the technical defects of existing dual-protein direct compound wall materials, which have loose structures and low encapsulation rates.

Description

Technical Field

[0001] This invention relates to the field of eugenol microcapsule preparation technology, specifically a preparation process for epicatechin-bridged dual-protein eugenol microcapsules. Background Technology

[0002] Heated cigarettes (HNB) rely on an external device to heat the cigarette core at a low temperature of 300-400℃ to generate an aerosol, avoiding the large amounts of harmful substances such as tar and polycyclic aromatic hydrocarbons produced by the high-temperature combustion of traditional cigarettes. This represents the mainstream development direction for reducing harm and tar in tobacco. Currently, tobacco additives are subject to increasingly stringent regulations, with a strict ban on the addition of chemical additives with carcinogenic and mutagenic risks. Natural functional flavorings have become the preferred raw materials for flavoring heated cigarettes.

[0003] Eugenol possesses the characteristic aroma of cloves, as well as antioxidant and antibacterial activities. It exhibits excellent compatibility with the natural aroma of tobacco, and its addition to the tobacco filler can optimize the flavor of the smoke and reduce the release of harmful substances. However, eugenol is highly lipid-soluble, has a low boiling point, and is highly volatile. It is easily lost through volatilization during tobacco processing, room temperature storage, and the heating process during smoking, resulting in uneven aroma release with each puff and limiting its large-scale use.

[0004] Protein-based wall materials have become the preferred substrate for flavor encapsulation due to their safety, edibility, and good biocompatibility. Zeadrin, with its strong hydrophobicity and excellent self-assembly film-forming properties, is well-suited for encapsulating fat-soluble eugenol; whey protein, with its outstanding hydrophilicity and emulsifying properties, can improve the water dispersibility of composite systems. However, the significant difference in hydrophilic / hydrophobic properties between these two types of proteins leads to poor structural stability in composite wall materials when directly compounded. They are prone to delamination and breakage during processing such as heating and stirring, resulting in technical drawbacks such as low encapsulation rates and poor sustained-release effects of eugenol.

[0005] Existing methods for improving protein cross-linking mostly employ chemical cross-linking agents such as glutaraldehyde and genipin, but these agents pose residual toxicity risks, do not comply with tobacco additive safety regulations, and cannot be used in heated cigarettes. Epicatechin, a natural plant polyphenol, contains multiple hydroxyl groups and aromatic ring structures in its molecule. It can bind to proteins through hydrogen bonds and hydrophobic interactions, exhibiting excellent thermal stability, making it a green and safe candidate for molecular bridging. Currently, there is no mature technology for using epicatechin to bridge zein-whey protein complexes to encapsulate eugenol and apply it to heated cigarettes; this is precisely the research and development starting point for this invention.

[0006] In summary, the existing technology has the following main problems: Eugenol volatilizes significantly during the processing, storage, and smoking of heated cigarettes, resulting in uneven aroma release. Simply adding it cannot achieve a long-lasting aroma.

[0007] The composite wall material formed by directly combining zein and whey protein has a loose and poor density, low encapsulation rate (usually less than 60%), and is prone to cracking when heated, thus failing to effectively protect eugenol.

[0008] While chemical crosslinking agents (glutaraldehyde, genipin, etc.) can help improve the stability of wall materials, their residual toxicity does not meet the safety standards for tobacco additives, making them impractical for use.

[0009] There is a lack of a green preparation process that utilizes natural polyphenol molecules to bridge two proteins, self-assembles them under neutral conditions to form an ordered porous wall material, and efficiently encapsulates eugenol.

[0010] In view of this, we propose a preparation process for epicatechin-bridged dual-protein eugenol microcapsules. Summary of the Invention

[0011] The purpose of this invention is to provide a preparation process for epicatechin-bridged dual-protein eugenol microcapsules to solve the problems mentioned in the background art.

[0012] To achieve the above objectives, the present invention provides the following technical solution: A process for preparing epicatechin-bridged dual-protein eugenol microcapsules, the process comprising: S1. Dissolve zein, eugenol and epicatechin in an aqueous ethanol solution with a volume fraction of 70% to 80% and stir until completely dissolved to obtain an organic phase; S2. Dissolve whey protein in deionized water to prepare a whey protein aqueous solution with a mass concentration of 0.5% to 2%, and then adjust the pH value to 6.5 to 7.5 with acid or alkali to obtain the aqueous phase; S3. Under stirring conditions, the organic phase obtained in step S1 is rapidly injected into the aqueous phase obtained in step S2, so that the volume ratio of the organic phase to the aqueous phase is 1:8 to 1:12. Stirring continues until the nanoparticles are formed and stabilized to obtain a nano suspension. S4. The nano suspension obtained in step S3 is subjected to rotary evaporation to remove ethanol and obtain a concentrated solution. S5. The concentrate obtained in step S4 is aged at 4-8°C for 12-24 hours, and then freeze-dried or spray-dried to obtain epicatechin-bridged double protein eugenol microcapsule powder.

[0013] Preferably, the mass ratio of zein to eugenol in step S1 is 1:0.15 to 1:0.25, and the mass ratio of zein to epicatechin is 1:0.06 to 1:0.12.

[0014] Preferably, the mass ratio of whey protein in step S2 to zein in step S1 is 3:1 to 5:1.

[0015] Preferably, the stirring speed in step S3 is 400-600 rpm, and the stirring time is 10-14 hours.

[0016] Preferably, the rotary evaporation temperature in step S4 is 35-45°C, the vacuum degree is -0.08 to -0.06 MPa, and the evaporation is carried out until the ethanol volume fraction is less than 1%.

[0017] Preferably, the freeze-drying conditions in step S5 are: pre-freezing temperature -50 to -40°C, pre-freezing time 4 to 6 hours, vacuum degree 10 to 20 Pa, and drying time 24 to 48 hours.

[0018] Preferably, the spray drying conditions in step S5 are: inlet air temperature 150-180℃, outlet air temperature 80-100℃, and feed flow rate 5-15mL / min.

[0019] Preferably, the average particle size of the obtained microcapsules is 100-500 nm, and the Zeta potential is -25 mV to -15 mV.

[0020] Preferably, the encapsulation rate of the obtained microcapsules is ≥80%, and the eugenol release rate is ≤5% under constant temperature conditions of 50℃ for 80 minutes and ≤15% under constant temperature conditions of 80℃ for 80 minutes.

[0021] Preferably, the resulting microcapsules are used as an additive in the heating element material of firecrackers to impart a clove aroma to the smoke and reduce irritation.

[0022] By employing the above technical solution, the present invention provides a preparation process for epicatechin-bridged dual-protein eugenol microcapsules. It possesses at least the following beneficial effects: This invention utilizes epicatechin as a natural molecular bridge, leveraging the dual effects of its phenolic hydroxyl groups forming hydrogen bonds with protein amino / carbonyl groups and the benzene rings undergoing hydrophobic association with protein hydrophobic segments to successfully bridge hydrophilic whey protein and hydrophobic zein. Under neutral pH conditions, the two proteins are induced to self-assemble into a continuous porous three-dimensional network wall material. This wall material has a dense structure, uniform thickness, and nanoscale micropores distributed on its surface, providing a stable embedding space for eugenol. Compared with the epicatechin-free system, the embedding rate is significantly improved, overcoming the technical defects of existing direct-combination wall materials with loose structures and low embedding rates. By limiting the preparation process to antisolvent nanoprecipitation combined with low-temperature curing and operation under neutral pH conditions, controllable particle size (100–500 nm) and good dispersion stability of microcapsules were achieved. The resulting microcapsules have a Zeta potential of -25 mV to -15 mV, and the system is not prone to aggregation, thus solving the structural instability problem caused by electrostatic repulsion or disordered agglomeration during the processing of existing protein composite wall materials. Through the molecular bridging effect mediated by epicatechin, the thermal stability and sustained-release performance of microcapsules are significantly improved, the release curve is smooth and there is no obvious burst release segment, thus achieving long-lasting aroma retention and solving the problems of serious volatilization loss of eugenol and uneven aroma release during the heating, processing, storage and smoking of cigarettes. By selecting natural food-grade raw materials (zein, whey protein, epicatechin, eugenol), and using non-covalent bonds (hydrogen bonds, hydrophobic interactions) to achieve protein bridging throughout the process, there is no chemical cross-linking reaction, no introduction of toxic functional groups, and no risk of cross-linking agent residue in the final product. After 30 days of storage, the eugenol retention rate reaches 92.36%, and the aroma retention rate exceeds 80% after simulated roller pressing sheet processing. This completely solves the problem of residual toxicity and non-compliance with tobacco additive safety regulations caused by chemical cross-linking agents (such as glutaraldehyde and genipin). By adding the obtained microcapsules to the core material of heated cigarettes, the aroma becomes rich, delicate, harmonious, free of impurities, non-irritating, pure, and comfortable. The consistency of aroma with each puff is significantly improved. This solves the quality defects of existing heated cigarettes, which are thin and irritating due to the direct addition of flavorings, and enhances the smoking experience for consumers. Attached Figure Description

[0023] The accompanying drawings, which are provided to further illustrate the invention, constitute a part of this application: Figure 1 This is a schematic diagram of the overall process for preparing a type of epicatechin-bridged dual-protein eugenol microcapsule according to the present invention. Figure 2 To characterize the morphology of the zein-whey protein complex system under different pH conditions and with or without epicatechin using scanning electron microscopy (SEM); Figure 3 Infrared spectral characterization of the zein-whey protein complex encapsulation system under different pH and epicatechin conditions; Figure 4 The results show the sustained-release properties of eugenol and microcapsules at different pH values ​​at 50℃ and 80℃. Detailed Implementation

[0024] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0025] See Figure 1 , Figure 1This is a schematic diagram of the overall process for preparing epicatechin-bridged dual-protein eugenol microcapsules according to the present invention. The preparation process includes: S1. Dissolve zein, eugenol and epicatechin in an aqueous ethanol solution with a volume fraction of 70% to 80% and stir until completely dissolved to obtain an organic phase; S2. Dissolve whey protein in deionized water to prepare a whey protein aqueous solution with a mass concentration of 0.5% to 2%, and then adjust the pH value to 6.5 to 7.5 with acid or alkali to obtain the aqueous phase; S3. Under stirring conditions, the organic phase obtained in step S1 is rapidly injected into the aqueous phase obtained in step S2, so that the volume ratio of the organic phase to the aqueous phase is 1:8 to 1:12. Stirring continues until the nanoparticles are formed and stabilized to obtain a nano suspension. S4. The nano suspension obtained in step S3 is subjected to rotary evaporation to remove ethanol and obtain a concentrated solution. S5. The concentrate obtained in step S4 is aged at 4-8°C for 12-24 hours, and then freeze-dried or spray-dried to obtain epicatechin-bridged double protein eugenol microcapsule powder.

[0026] Eugenol is used as the core material; zein and whey protein are used as composite wall materials; epicatechin is used as a molecular cross-linking bridge. The principle includes: epicatechin relies on the phenolic hydroxyl group to form hydrogen bonds with the amino / carbonyl group of the protein, and the benzene ring to form hydrophobic association with the hydrophobic chain of the protein, bridging the hydrophilic and hydrophobic proteins, and self-assembling under neutral conditions to form a continuous porous three-dimensional network wall material, encapsulating eugenol in the cavity.

[0027] In step S1, the mass ratio of zein to eugenol is 1:0.15 to 1:0.25, and the mass ratio of zein to epicatechin is 1:0.06 to 1:0.12. The mass ratio of whey protein in step S2 to zein in step S1 is 3:1 to 5:1; The stirring speed in step S3 is 400-600 rpm, and the stirring time is 10-14 hours; In step S4, the rotary evaporation temperature is 35–45°C, the vacuum degree is -0.08–-0.06 MPa, and the evaporation is carried out until the ethanol volume fraction is less than 1%. The freeze-drying conditions described in step S5 are: pre-freezing temperature -50 to -40°C, pre-freezing time 4 to 6 hours, vacuum degree 10 to 20 Pa, and drying time 24 to 48 hours. The spray drying conditions described in step S5 are: inlet air temperature 150-180℃, outlet air temperature 80-100℃, and feed flow rate 5-15mL / min; The obtained microcapsules have an average particle size of 100–500 nm and a Zeta potential of -25 mV to -15 mV. The encapsulation efficiency of the obtained microcapsules is ≥80%, and the eugenol release rate is ≤5% after 80 minutes at a constant temperature of 50℃ and ≤15% after 80 minutes at a constant temperature of 80℃. The resulting microcapsules are used as an additive in heated firework core materials to impart a clove aroma to the smoke and reduce irritation.

[0028] Example Preparation of epicatechin-bridged double protein eugenol microcapsules Weigh 0.5g of Zein and dissolve it in 20mL of 75% ethanol. Stir for 1 hour to dissolve, then add 0.1g of Eug and 0.04g of EC. Stir magnetically overnight to ensure complete dissolution. Weigh 2g of WPI and dissolve it in 200mL of deionized water to obtain a 1% (w / v) solution. Adjust the pH to 3.0 or 7.0 with 0.1M HCl or NaOH and stir until completely dissolved. Store at 4℃ for later use. Under magnetic stirring (500 rpm), 10 mL of organic phase was quickly drawn up with a syringe and injected into 100 mL of aqueous phase at one time (the volume ratio of organic phase to aqueous phase is 1:10). Stirring was continued at room temperature for 12 hours to allow the nanoparticles to fully form and stabilize, thus obtaining a nano suspension. The nano suspension was transferred to a rotary evaporator and rotary evaporated at 40°C and a vacuum of -0.07 MPa until the ethanol volume fraction was less than 1%, thus obtaining a concentrated solution. The concentrate was aged in a 4°C refrigerator for 18 hours, and then freeze-dried under the following conditions: pre-freezing temperature -45°C, pre-freezing time 5 hours, vacuum degree 15 Pa, and drying time 36 hours, resulting in a light yellow loose powder, which is epicatechin-bridged double protein eugenol microcapsules. The obtained microcapsules were tested and found to have an average particle size of 142 nm, a zeta potential of -22 mV, and an encapsulation rate of 85.24%. Scanning electron microscopy showed that the microcapsules had a continuous porous three-dimensional network structure with uniform wall thickness and nanoscale micropores distributed on the surface. Among them, Zein is zein, WPI is whey protein, EC is epicatechin, and Eug is eugenol.

[0029] See Figure 2 , Figure 2 To characterize the morphology of the zein-whey protein complex system under different pH conditions and with and without epicatechin using scanning electron microscopy (SEM), the results are as follows: Figure 2As shown, in system (A) without epicatechin at pH 3.0, the protein mainly exists as monodisperse nanoparticles with clear boundaries and monodisperse spherical shape. The boundaries are clear, with no obvious aggregation or fusion, and the distribution is discrete. This indicates that the two proteins undergo phase separation due to charge difference under this condition and do not form a continuous wall material network. At pH 7.0 without epicatechin (B), the protein particles undergo random fusion to form dense amorphous block aggregates without obvious pores and ordered structure, indicating that the protein itself cannot form a stable microcapsule structure.

[0030] When epicatechin is introduced as a molecular bridge, the morphology of the system changes significantly: under pH 3.0 (C), the boundaries between protein particles gradually become blurred, forming a semi-continuous cluster structure composed of multiple nanoparticles, with reduced porosity and increased wall material density, indicating that epicatechin mediates the interaction between the two proteins, but the degree of assembly is limited due to pH influence; under pH 7.0 (D), the protein particles are completely fused, forming a highly continuous, uniform, and porous three-dimensional network structure with uniform wall material thickness and nanoscale micropores distributed on the surface, exhibiting typical microcapsule wall material characteristics.

[0031] The transformation from monodisperse particles and random aggregates to ordered continuous wall materials demonstrates that epicatechin successfully acts as a molecular bridge, binding both zein and whey protein through hydrogen bonds and hydrophobic interactions, overcoming electrostatic repulsion between proteins and inducing their ordered assembly to form a composite wall material. Simultaneously, the uniform porous network structure in group D provides a stable embedding space for the hydrophobic core material eugenol, a structure that cannot be formed in systems without epicatechin. This further confirms that eugenol has been successfully embedded in the epicatechin-mediated protein composite wall material, and that neutral pH conditions are more conducive to the complete formation of the wall material and the embedding of the core material.

[0032] See Figure 3 , Figure 3 Infrared spectral characterization of the zein-whey protein co-encapsulated system under different pH values ​​and with the influence of epicatechin. Infrared spectral analysis of the zein-whey protein co-encapsulated eugenol system was conducted, and the molecular mechanism mediated by epicatechin was elucidated based on the characteristic peak shifts and transmittance evolution.

[0033] 3397.96cm -1 3406.64cm -1 The peak positions were observed at pH 3.0 and pH 7.0 without the addition of epicatechin, due to the stretching vibration of the amide NH and hydroxyl OH groups in the system. After the introduction of epicatechin, the peak positions shifted to 3402.78 cm⁻¹. -1 3413.39cm -1 The overall trend is towards higher wavenumbers. 2928.38cm -1 2926.93cm-1 The peak is a characteristic of aliphatic CH stretching; after adding epicatechin, it changes to 2927.90 cm⁻¹. -1 2927.41cm -1 The peak position showed a slight low wavenumber shift. Two bands, along with the amide characteristic peak, exhibited a clear transmittance differentiation: the transmittance of all three characteristic peaks decreased at pH 3.0, while it increased simultaneously at pH 7.0. Decreased transmittance indicates enhanced infrared absorption intensity, reflecting intensified molecular association. In an acidic environment, epicatechin phenolic hydroxyl groups form numerous intermolecular hydrogen bonds with protein polar groups, increasing molecular aggregation and strengthening group vibrational absorption; however, the proteins in this system are all positively charged, electrostatic repulsion causes phase separation, and amino protonation masks active sites, limiting bridging. The amide I band remained stable at 1656.55 cm⁻¹. -1 The absence of displacement indicates that the chemical environment of the peptide bond C=O did not change, and only local weak hydrogen bond association was formed, failing to construct a continuous composite wall material. Eugenol only adhered to the surface of the protein particles.

[0034] At pH 7.0, the overall transmittance increases, while the infrared absorption intensity of functional groups decreases. At this point, the electrostatic repulsion of the protein weakens, the peptide chain conformation unfolds, and epicatechin forms stable intermolecular hydrogen bonds with the protein carbonyl and amino groups via its phenolic hydroxyl groups. Simultaneously, the hydrophobic benzene ring interacts with the hydrophobic segments of the protein and the hydrophobic groups of eugenol. Regulated by multiple forces, the originally dense aggregated structure dissociates and rearranges, resulting in a more loosely ordered molecular arrangement. The amide I band increases from 1656.07 cm⁻¹. -1 Shifted to 1651.25 cm -1 The peak position shifted to lower wavenumbers, confirming that the carbonyl group participates in hydrogen bond association, and the molecular binding stability is greatly improved.

[0035] Pure eugenol at 1640.25cm -1 1605.75cm -1 1266.45cm -1 The characteristic peaks completely disappeared in the composite spectrum, proving the absence of free eugenol and indicating that the core material was effectively encapsulated within the protein-epicatechin composite wall material. Overall, pH 3.0 only resulted in localized hydrogen bond aggregation, leading to poor assembly; pH ​​7.0, on the other hand, facilitated orderly cross-linking of the protein through the synergistic effects of hydrogen bonds and hydrophobic interactions, resulting in a more stable encapsulation structure. The spectral conclusions and scanning electron microscopy morphological characterization corroborated each other.

[0036] Without epicatechin, proteins exhibit phase separation due to charge repulsion at acidic pH 3.0 and random aggregation at neutral pH 7.0. With the addition of epicatechin, ordered cross-linking is achieved in the neutral environment through the dual effects of hydrogen bonding and hydrophobicity, forming a porous continuous wall material. The complete disappearance of the characteristic peak of pure eugenol confirms the encapsulation of all components, and the conclusions of SEM and infrared characterization corroborate each other.

[0037] See Figure 4 , Figure 4 The sustained-release performance of eugenol and microcapsules with different pH values ​​at 50℃ and 80℃ is presented. The release rate of pure eugenol at 50℃ for 80 min was 13.1%, and at 80℃ for 80 min was 27.6%. Introducing epicatechin as a molecular bridge significantly improved the sustained-release performance of both systems. The pH 7.0+EC sample showed the best sustained-release effect at both temperatures, with a release rate of only 2.4% at 50℃ for 80 min and only 11.9% at 80℃ for 80 min. The release curves were generally flat with no obvious burst release. The eugenol release increased slowly over time, demonstrating outstanding effects in long-lasting aroma retention and reducing losses during tobacco processing and storage, making it suitable for the daily production and storage requirements of heated cigarette raw materials.

[0038] The addition of microcapsules significantly improved the sensory quality of HNB cigarettes. The best sensory quality was observed when the additive was at pH 7.0 and contained EC, with a marked increase in aroma intensity and quality, a pure and pleasant aroma, significantly reduced irritation, a mellow smoke, and a sweet aftertaste. This effectively reduced the variation in aroma between puffs and improved the inconsistency between puffs. Table 1 lists the sensory evaluation results of HNB cigarettes with microcapsules at different pH values.

[0039]

[0040] The microcapsules were sealed and stored for 30 days under constant temperature and humidity conditions (25℃, 60% relative humidity). The mass of eugenol in the microcapsules was calculated according to the encapsulation efficiency calculation method. The eugenol retention after 30 days was detected. The results showed that after the addition of EC, the eugenol retention rate in microcapsules at pH 3.0 was 89.51%, and the eugenol retention rate in microcapsules at pH 7.0 was 92.36%. This indicates that under neutral conditions, the system can more effectively improve the storage stability of eugenol, help delay the release of eugenol, and improve its aroma retention ability. Retention rate (%) = .

[0041] The processing of cigarette sheets using a simulated roller pressing method (mixing, rolling, and drying at 80 °C) was compared with that of pure eugenol and microcapsules. Pure eugenol had an aroma retention rate of only 41.2% after processing, with significant volatilization loss during the high-temperature drying stage. In this invention, the aroma retention rate of microcapsules can reach over 80% under both pH systems, which can withstand mechanical shearing and temperature fluctuations during processing and is suitable for the industrial production process of heated cigarette sheets.

[0042] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0043] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A preparation process for epicatechin-bridged dual-protein eugenol microcapsules, characterized in that, The process includes: S1. Dissolve zein, eugenol and epicatechin in an aqueous ethanol solution with a volume fraction of 70% to 80% and stir until completely dissolved to obtain an organic phase; S2. Dissolve whey protein in deionized water to prepare a whey protein aqueous solution with a mass concentration of 0.5% to 2%, and then adjust the pH value to 6.5 to 7.5 with acid or alkali to obtain the aqueous phase; S3. Under stirring conditions, the organic phase obtained in step S1 is rapidly injected into the aqueous phase obtained in step S2, so that the volume ratio of the organic phase to the aqueous phase is 1:8 to 1:

12. Stirring continues until the nanoparticles are formed and stabilized to obtain a nano suspension. S4. The nano suspension obtained in step S3 is subjected to rotary evaporation to remove ethanol and obtain a concentrated solution. S5. The concentrated solution obtained in step S4 is aged at 4℃~8℃ for 12 hours~24 hours, and then freeze-dried or spray-dried to obtain epicatechin-bridged double protein eugenol microcapsule powder.

2. The preparation process of the epicatechin-bridged dual-protein eugenol microcapsules according to claim 1, characterized in that, In step S1, the mass ratio of zein to eugenol is 1:0.15 to 1:0.25, and the mass ratio of zein to epicatechin is 1:0.06 to 1:0.

12.

3. The preparation process of the epicatechin-bridged dual-protein eugenol microcapsules according to claim 1, characterized in that, The mass ratio of whey protein in step S2 to zein in step S1 is 3:1 to 5:

1.

4. The preparation process of the epicatechin-bridged dual-protein eugenol microcapsules according to claim 1, characterized in that, The stirring speed in step S3 is 400-600 rpm, and the stirring time is 10-14 hours.

5. The preparation process of the epicatechin-bridged dual-protein eugenol microcapsules according to claim 1, characterized in that, The rotary evaporation in step S4 is carried out at a temperature of 35°C to 45°C and a vacuum degree of -0.08 MPa to -0.06 MPa until the ethanol volume fraction is less than 1%.

6. The preparation process of the epicatechin-bridged dual-protein eugenol microcapsules according to claim 1, characterized in that, The freeze-drying conditions described in step S5 are as follows: pre-freezing temperature -50℃ to -40℃, pre-freezing time 4 hours to 6 hours, vacuum degree 10Pa to 20Pa, and drying time 24 hours to 48 hours.

7. The preparation process of epicatechin-bridged dual-protein eugenol microcapsules according to claim 1, characterized in that, The conditions for spray drying in step S5 are: inlet air temperature 150℃~180℃, outlet air temperature 80~100℃, and feed flow rate 5mL / min~15mL / min.

8. The preparation process of the epicatechin-bridged dual-protein eugenol microcapsules according to claim 1, characterized in that, The average particle size of the obtained microcapsules is 100 nm to 500 nm, and the zeta potential is -25 mV to -15 mV.

9. The preparation process of epicatechin-bridged dual-protein eugenol microcapsules according to claim 1, characterized in that, The encapsulation efficiency of the obtained microcapsules is ≥80%, and the eugenol release rate is ≤5% under constant temperature of 50℃ for 80 minutes and ≤15% under constant temperature of 80℃ for 80 minutes.

10. The preparation process of epicatechin-bridged dual-protein eugenol microcapsules according to claim 1, characterized in that, The resulting microcapsules are used as an additive in heated firework core materials to impart a clove aroma to the smoke and reduce irritation.

Images