Coconut oil emulsion loaded with lemon essential oil as well as preparation method and application of coconut oil emulsion

Abstract

The invention discloses coconut oil emulsion loaded with lemon essential oil as well as a preparation method and application thereof, and belongs to the technical field of coconut oil emulsion processing. The coconut oil emulsion is used for solving the technical problems in the prior art that the particle size and the stability of the coconut oil emulsion applied to the baked food and the influence of the coconut oil emulsion on the food flavor and the nutritional value of the baked food need to be further improved. And adding the lemon essential oil bag and pulp into a reaction system. A homogeneous dispersion liquid is formed by carboxylated nanocellulose, lemon essential oil wrapping pulp and mixed coconut oil, emulsion droplet immobilization is achieved through chitosan, lecithin and a Ca polyelectrolyte network, and the load type coconut oil emulsion which is small in particle size, high in stability and excellent in flavor retention is prepared. And the method is successfully applied to cake baking so as to improve the texture and taste quality of cakes.

Description

Technical Field

[0001] This invention relates to the field of coconut oil emulsion processing technology, specifically to a coconut oil emulsion loaded with lemon essential oil, its preparation method, and its application. Background Technology

[0002] Coconut oil, as a natural plant oil, is rich in medium-chain fatty acids (such as lauric acid, which accounts for more than 60%), and has physiological functions such as antibacterial, antioxidant, and blood lipid regulation. It is widely used in the food, cosmetic, and pharmaceutical fields. Lemon essential oil, on the other hand, is a type of natural volatile aromatic substance mainly derived from lemon peel. It has good aroma characteristics and certain antioxidant, antibacterial, and other biological activities, and is widely used in food, beverages, baked goods, and daily chemical products.

[0003] However, coconut oil is solid or semi-solid at room temperature and has poor fluidity. When applied directly, it is prone to oxidation, which can lead to flavor deterioration and loss of functional components, limiting its use in high-temperature processing and long-term storage. Lemon essential oil contains a large number of monoterpenes and sesquiterpenes, which are highly volatile, hydrophobic, easily oxidized and decomposed, and have poor thermal stability. In food processing, especially baking, it is very easy to suffer aroma loss and oxidative deterioration, resulting in flavor decay and quality decline in the product.

[0004] Emulsion technology is a common approach to improve the dispersibility and stability of hydrophobic active substances. Conventional water-in-oil (O / W) emulsions can reduce volatilization loss to a certain extent. However, traditional emulsions often rely on low-molecular-weight surfactants, which have limited interfacial film strength and are easily affected by factors such as shearing, centrifugation, and heating during processing, resulting in demulsification, aggregation, or stratification. Furthermore, the oil droplet interface structure of traditional emulsion systems is relatively weak, making it unable to effectively resist Oswald ripening and physical instability during long-term storage. This means that the flavor retention of emulsions in practical applications still falls short of the needs of the food industry. Moreover, in food applications that require heat processing, such as baking, the substitution of fat content and the maintenance of flavor quality face a dual challenge. How to achieve good texture, quality, and flavor performance while reducing or partially replacing fat is a long-standing technical issue of concern in the baking industry. Summary of the Invention

[0005] The purpose of this invention is to provide a coconut oil emulsion loaded with lemon essential oil, its preparation method, and its application, in order to solve the technical problem that the particle size, stability, and impact on the flavor and nutritional value of coconut oil emulsions applied to baked goods in the prior art need to be further improved.

[0006] The objective of this invention can be achieved through the following technical solution: a method for preparing a coconut oil emulsion loaded with lemon essential oil, comprising the following steps: S1. Mix carboxylated nanocellulose and citrate buffer solution and homogenize. Add lemon essential oil packet and slurry to the reaction system and stir for 10-15 min to obtain water-based mixed slurry. S2. Heat the coconut oil to 30-35℃ until melted, then add lemon essential oil, tocopherol and lecithin, mix and stir for 10-15 minutes to obtain mixed coconut oil; S3. Under high-speed stirring, add the mixed coconut oil to the water-based slurry at a temperature of 30-35℃, emulsify and mix for 3-4 minutes, transfer the slurry to a high-pressure homogenizer for high-pressure homogenization to obtain a homogenized dispersion. S4. While stirring, add chitosan solution to the homogeneous dispersion, add citric acid to the reaction system, adjust the pH of the system to 4-4.5, stir for 20-30 min, add calcium chloride solution dropwise to the reaction system, stir for 6-8 min, lower the temperature of the reaction system to 5-10℃, and let it stand for 10-12 h to obtain a coconut oil emulsion loaded with lemon essential oil.

[0007] Furthermore, in step S1, the ratio of the carboxylated nanocellulose, citrate buffer, and lemon essential oil package and pulp is 2-3g:100mL:100mL, and the citrate buffer is composed of 0.1M citric acid and sodium citrate, with a pH of 5.8-6.2.

[0008] Furthermore, in step S2, the weight ratio of coconut oil, lemon essential oil, tocopherol, and lecithin is 20:2.6-2.8:0.01:0.1.

[0009] Furthermore, in step S3, the high-speed stirring speed is 13000-15000 rpm, the oil-water ratio of the mixed coconut oil and water-based slurry is 1:5-7, the pressure of the high-pressure homogenization is 60-70 MPa, the temperature is 10-15℃, and the number of homogenization cycles is 3.

[0010] Furthermore, in step S4, the stirring speed is 200-300 rpm, the volume ratio of the homogeneous dispersion, chitosan solution, and calcium chloride solution is 500:70:50, the chitosan solution is composed of 0.5 mol / L citric acid aqueous solution, chitosan, and lecithin at a ratio of 100 mL:3-4 g:1-2 g, and the calcium chloride solution is composed of calcium chloride and deionized water at a ratio of 1 g:20 mL.

[0011] Furthermore, the preparation method of carboxylated nanocellulose is as follows: nanocellulose, TEMPO, and deionized water are mixed and homogenized. Sodium hydroxide solution is added to the reaction system to adjust the pH of the system to 9.5-10.5. The reaction system is cooled to 20-25℃. Sodium hypochlorite solution is added dropwise to the reaction system. While adding sodium hypochlorite solution, sodium hydroxide solution is added dropwise to the reaction system to maintain the pH of the system at 9.5-10.5. After the addition is completed, the reaction is kept at the temperature for 90-120 min. After post-treatment, carboxylated nanocellulose with a molecular weight greater than 10000 Da is obtained.

[0012] Furthermore, the ratio of the nanocellulose, TEMPO, deionized water, and sodium hypochlorite solution is 10g:0.1-0.15g:1L:10mL. The sodium hypochlorite solution is composed of sodium hypochlorite and deionized water at a ratio of 1g:5mL. The post-treatment includes: after the reaction is complete, adding sodium thiosulfate solution to the reaction system, then placing it in a dialysis bag with a molecular weight cutoff of 7000Da, placing the dialysis bag in deionized water, changing the deionized water every 6 hours, and after dialysis for 48 hours, transferring the material in the dialysis bag to a freeze dryer at a temperature of -30℃ for freeze drying to obtain carboxylated nanocellulose.

[0013] Furthermore, the preparation method of lemon essential oil packets and pulp is as follows: β-cyclodextrin and deionized water are mixed and stirred, the temperature of the reaction system is raised to 45-55℃, and the system is stirred until dissolved. The stirring speed is increased to 4000-5000 rpm, lemon essential oil is added dropwise to the reaction system, and after the addition is completed, the mixture is stirred and dispersed for 10-15 minutes. After post-treatment, lemon essential oil packets and pulp are obtained.

[0014] Furthermore, the ratio of β-cyclodextrin, deionized water, and lemon essential oil is 8-9g:100mL:1g. The post-treatment includes: after the reaction is complete, the reaction solution is cooled to 5-8℃ and allowed to stand for 3-4 hours. The reaction solution is then placed in a centrifuge, centrifuged at 9000-10000rpm for 5 minutes, and the upper layer of suspended free oily matter is skimmed off to obtain lemon essential oil packets and pulp.

[0015] The present invention also proposes a coconut oil emulsion loaded with lemon essential oil, which is prepared by the above-mentioned method for preparing a coconut oil emulsion loaded with lemon essential oil.

[0016] The present invention also proposes an application of a coconut oil emulsion loaded with lemon essential oil, which is prepared by the above-mentioned method for preparing a coconut oil emulsion loaded with lemon essential oil and applied to the processing of baked goods to enhance the flavor and nutritional value of baked goods.

[0017] The present invention has the following beneficial effects: 1. This invention involves carboxylating nanocellulose using a TEMPO system to imbue its surface with numerous carboxyl groups, resulting in carboxylated nanocellulose with high dispersibility and interfacial activity. This material not only forms a stable three-dimensional fiber network in aqueous phase, improving the viscosity and yield stress of the continuous phase, but also accumulates as Pickering-like particles at the oil-water interface during emulsification, constructing an initial interfacial framework and inhibiting oil droplet aggregation through both physical barrier and electrostatic repulsion. In an aqueous system coexisting with β-cyclodextrin inclusion complexes, carboxylated nanocellulose also promotes the uniform dispersion of flavor inclusion particles, laying the foundation for achieving micron-sized particles and narrow distribution in subsequent homogenization steps, and improving the uniformity of emulsion particle size and storage stability in coconut oil emulsions loaded with lemon essential oil.

[0018] 2. This invention involves encapsulating lemon essential oil with β-cyclodextrin under high shear and suitable temperature conditions. This allows the essential oil molecules to embed into the hydrophobic cavities of the cyclodextrin, significantly reducing volatility and oxidation sensitivity, thus solving the problems of poor dispersion and easy loss of essential oil in the aqueous phase. After the inclusion complex enters the aqueous phase, it forms a structurally stable aqueous system together with carboxylated nanocellulose, achieving uniform dispersion and storage protection of flavor components. At the same time, the additional free lemon essential oil introduced into the oil phase can rapidly release aroma in the early stage of baking, complementing the slow-release effect of the encapsulated essential oil in the later stage of baking and during storage. This results in a two-stage characteristic of initial release and prolonged slow release of the overall flavor, improving the heat resistance and retention rate of lemon essential oil, and ultimately resulting in improved taste scores and a more lasting and mellow aroma in the final cake product.

[0019] 3. This invention involves introducing chitosan into a homogeneous dispersion under acidic conditions, giving it a positive charge. This allows it to undergo directional electrostatic recombination with negatively charged carboxylated nanocellulose, lecithin head groups, and citrate, preferentially forming a polyelectrolyte complex layer at the emulsion droplet interface. This process is achieved by adding CaC... After low-temperature ripening, Ca Further ionic cross-linking with carboxyl and citrate groups makes the composite shell more dense and flexible, while forming a weak gel network in the continuous phase. The interfacial shell provides mechanical barrier and charge repulsion, while the continuous phase network provides rheological stability support. The coupling of the two significantly enhances the emulsion's resistance to polymerization, Oswald ripening, and gravity separation, improving the emulsion's storage stability. In addition, this structured emulsion helps stabilize bubbles and improve tissue support in baking batter, thereby improving the bite and chewiness of cakes while maintaining good elasticity and sensory scores, demonstrating the dual advantages of structure and flavor of the emulsion in baking applications. Moreover, the coconut oil emulsion, after emulsification and dilution, reduces the substitution of oils while achieving good tissue structure, textural properties, and flavor performance, making baked goods healthier and more nutritious. Attached Figure Description

[0020] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0021] Figure 1 Photograph of a coconut oil emulsion sample loaded with lemon essential oil prepared in Example 3 of this invention; Figure 2 Top view (right) of a cake test sample prepared with coconut oil emulsion loaded with lemon essential oil in accordance with Example 3 of the present invention, and top view (left) of a control sample prepared with all-oil cake. Figure 3 Cross-sectional photograph (right) of a cake test sample prepared with coconut oil emulsion loaded with lemon essential oil in accordance with Example 3 of the present invention, and cross-sectional photograph (left) of a control sample prepared with all-oil cake. Detailed Implementation

[0022] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments. 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.

[0023] In this application, the effective component content of nanocellulose is 99.9%, the product grade is food grade, and it is selected from commercially available products of Wuhan Lanabai Pharmaceutical Chemical Co., Ltd., with product number lnb-1130; In this application, TEMPO is tetramethylpiperidine oxide, CAS number 2564-83-2; In this application, the β-cyclodextrin is food-grade β-cyclodextrin, selected from commercially available products of Shandong Xinxiong Biotechnology Co., Ltd.; In this application, the lemon essential oil is food-grade natural lemon essential oil with an effective ingredient content of 99%, selected from commercially available products of Taian Yingshun Chemical Co., Ltd. In this application, the coconut oil has an effective ingredient content of 99%, is of food grade, and is selected from commercially available products of Jinan Mingde Biotechnology Co., Ltd. In this application, the lecithin is food-grade soybean lecithin with a content of 99%, selected from commercially available products of Hebei Runbu Biotechnology Co., Ltd. In this application, the chitosan is food-grade water-soluble chitosan with an effective substance content of 99%, selected from commercially available products of Xi'an Lavia Biotechnology Co., Ltd.

[0024] Example 1

[0025] This embodiment provides a method for preparing a coconut oil emulsion loaded with lemon essential oil, specifically including the following steps: Step 1: Preparation of carboxylated cellulose nanoparticles Sodium hypochlorite and deionized water were mixed evenly at a ratio of 1g:5mL to obtain a sodium hypochlorite solution; Weigh 10g of nanocellulose, 0.1g of TEMPO, and 1L of deionized water and add them to a high-speed homogenizer. Set the speed to 10000rpm and the homogenization time to 3min. Transfer the homogenate to a reaction flask and stir. Add 2mol / L sodium hydroxide solution to the reaction flask to adjust the pH of the system to 9.5. Cool the reaction flask to 20℃ and add 10mL of sodium hypochlorite solution dropwise to the reaction flask. At the same time as adding sodium hypochlorite solution, add 1mol / L sodium hydroxide solution dropwise to the reaction flask to maintain the pH of the system at 9.5. After the addition is complete, keep the reaction at this temperature for 90min. Add 20mL of 8wt% sodium thiosulfate solution to the reaction flask and then place it in a dialysis bag with a molecular weight cutoff of 7000Da. Place the dialysis bag in deionized water and change the deionized water every 6h. After dialysis for 48h, transfer the material in the dialysis bag to a freeze dryer at -30℃ and freeze-dry it. Screen out carboxylated nanocellulose with a molecular weight cutoff >10000Da.

[0026] In the reaction, TEMPO acts as a catalyst, activated by sodium hypochlorite to become an ammonium oxoion intermediate. This intermediate then selectively oxidizes the primary alcohol hydroxyl groups (C6 hydroxyl groups) on the surface of the cellulose molecular chain to carboxylate structures. The oxidation is then terminated by sodium thiosulfate, which removes residual oxidant. After dialysis and lyophilization, carboxylated cellulose nanoparticles with a molecular weight greater than 10,000 Da and a large number of carboxyl groups on the surface are obtained. TEMPO does not disrupt the β-1,4-glycosidic bonds of the cellulose backbone, nor does it extensively oxidize the C2 / C3 hydroxyl groups, thus preserving the original microfibril crystal structure of cellulose and ensuring its mechanical properties and particle structure stability. Simultaneously, the increased degree of carboxylation significantly increases the negative charge density on the cellulose surface, forming stable electrostatic repulsion during aqueous dispersion, thereby enhancing its dispersibility in water and improving its ability to form network structures. Carboxylation enhances interfacial adsorption capacity, enabling cellulose to more tightly arrange itself at the oil droplet interface, forming a stronger particle-stabilized layer. The electrostatic repulsion induced by the negative charge of its carboxylates effectively prevents oil droplet aggregation, significantly improving the physical stability of the emulsion. Furthermore, carboxylated cellulose forms a stable three-dimensional support network in the continuous phase, reducing oil droplet migration rates and inhibiting stratification and Oswald ripening. Carboxylated cellulose can also interact with chitosan and Ca... 2+Polyelectrolytes can undergo synergistic compounding in subsequent steps, further enhancing the interfacial density and storage stability of the emulsion system.

[0027] Step 2: Prepare lemon essential oil packets and paste

[0028] Weigh out 80g of β-cyclodextrin and 1L of deionized water and add them to the reaction flask. Stir at 600rpm and raise the temperature of the reaction flask to 45℃. Stir until the system is dissolved. Increase the stirring speed to 4000rpm and add 10g of lemon essential oil dropwise to the reaction flask. After the addition is complete, stir and disperse for 10min. Cool the reaction solution to 5℃ and let it stand for 3h. Place the reaction solution in a centrifuge and set the centrifugation speed to 9000rpm. Centrifuge for 5min and skim off the upper layer of suspended free oil to obtain lemon essential oil packets and pulp.

[0029] In the reaction, β-cyclodextrin dissolves under heating conditions and forms a uniform dispersion after high-speed stirring. Lemon essential oil added to the system is then subjected to shear force, forming small oil droplets that readily and rapidly enter the hydrophobic cavities of the β-cyclodextrin. As stirring continues, β-cyclodextrin molecules capture and stably encapsulate lemon essential oil molecules through van der Waals forces, hydrophobic interactions, and spatial nesting effects, forming a non-covalently driven inclusion complex. During the subsequent cooling process, the solubility of the inclusion complex decreases, causing some inclusion structures to precipitate in microcrystal form and aggregate to form a dispersible slurry. Subsequent centrifugation at 10,000 rpm effectively separates unencapsulated free oil droplets, resulting in an inclusion slurry with higher purity and stability, thus providing a uniform and controllable flavor carrier raw material for subsequent systems.

[0030] The cavity of β-cyclodextrin forms a physical barrier for hydrophobic essential oil molecules, effectively slowing down direct contact between the essential oil and heat, oxygen, and light, thereby reducing the volatilization loss and oxidative degradation of lemon essential oil during high-temperature processing such as baking. The inclusion complex consists of hydrophilic hydroxyl groups on its surface, enabling it to be stably dispersed in an aqueous system, facilitating uniform distribution in water-based mixtures and mitigating aggregation and stratification of lemon essential oil due to its hydrophobicity. As a flavor-sustaining structure, the inclusion complex allows free and included essential oils to coexist in the final emulsion system, enabling the product to retain more flavor compounds during processing and storage, while gradually releasing them during consumption, thus maintaining high flavor persistence. The stable oil-phase microparticles of the inclusion complex can serve as part of the droplet structure, enhancing the interfacial membrane density and droplet structural stability through interaction with the cellulose network.

[0031] Step 3: Prepare water-based mixed slurry and mixed coconut oil

[0032] Sodium citrate was added to 0.1M citric acid to adjust the pH of the system to 5.8, thus obtaining a citrate buffer solution. Weigh 20g of carboxylated nanocellulose and 1L of citrate buffer into a high-speed homogenizer, set the speed to 10000rpm and the homogenization time to 3min. Transfer the homogenate to a reaction flask and stir, set the stirring speed to 1000rpm. Add 1L of lemon essential oil packet and slurry to the reaction flask and stir for 10min to obtain a water-based mixed slurry. Weigh out 40g of coconut oil and add it to the reaction flask. Heat the reaction flask to 30℃ and wait for the coconut oil to melt. Then add 5.2g of lemon essential oil, 0.02g of tocopherol and 0.2g of lecithin to the reaction flask and stir for 10 minutes to obtain mixed coconut oil.

[0033] During the reaction, the carboxylated cellulose nanofibrils disperse in a citrate buffer solution, and the surface carboxyl groups ionize, generating a large number of negative charges. This causes electrostatic repulsion between the cellulose microfibrils, promoting uniform dispersion and the formation of a stable aqueous network structure. When lemon essential oil inclusion paste is added to this aqueous system, the hydroxyl groups on the inclusion complex surface can form hydrogen bonds with cellulose, enhancing the viscoelasticity and structural continuity of the system. The cellulose network restricts the migration of the inclusion complex, improving the uniformity of dispersion. In a neutral to slightly acidic buffer environment, the carboxyl groups of cellulose partially ionize, giving it both water solubility and structural support capabilities, which helps to form a suitable viscosity and stable interface. The system is a continuous aqueous phase. In the oil phase, coconut oil is completely melted upon heating, forming a continuous liquid oil matrix. The added lemon essential oil, as a flavor carrier, is directly dissolved in the oil phase, enabling the storage and dispersion of the free essential oil. Tocopherol, as a natural antioxidant, can inhibit the oxidation reaction of oils, protect lemon essential oil from thermal and oxidative degradation, and extend the shelf life of the emulsion. Lecithin has an amphiphilic molecular structure, with its lipophilic end preferentially dissolving in the oil phase, while its hydrophilic end can migrate to the interface during subsequent emulsification. This helps reduce interfacial tension and coordinate the breakup process of oil droplets in a high-speed shear environment, allowing the droplets to form rapidly and maintain a small particle size during homogenization.

[0034] Step 4: Prepare homogeneous dispersion

[0035] Weigh 1L of water-based mixed slurry and add it to the reaction flask. Stir the slurry at 13000rpm. Cool the reaction flask to 30℃. Add 200g of mixed coconut oil to the reaction flask and emulsify and disperse for 3min. Cool the reaction liquid to 10℃. Transfer the emulsified slurry to a high-pressure homogenizer. Set the high-pressure homogenization pressure to 60MPa and the homogenization cycle to 3 times. Perform high-pressure homogenization to obtain a homogenized dispersion.

[0036] In the reaction, the water-based mixed slurry contains uniformly dispersed carboxylated nanocellulose and lemon essential oil inclusion complexes, while the mixed coconut oil contains coconut oil, free lemon essential oil, and lecithin. Under high-speed shear force, large oil droplets are repeatedly stretched, split, and refined into pre-emulsified micron-sized oil droplets. At this stage, lecithin rapidly migrates to the oil / water interface, and its amphiphilic structure reduces interfacial tension, helping the newly formed small oil droplets remain stable in the shear field. At the same time, carboxylated nanocellulose, due to its large amount of negative charge, spontaneously adsorbs onto the surface of the oil droplets, stabilizing the droplets through steric hindrance and charge repulsion, forming a preliminary particle interface layer. The lemon essential oil inclusion complex is distributed in the aqueous phase in the form of microparticles and, together with the cellulose network, constructs a continuous phase structure, improving the viscoelasticity of the emulsion system. Under high pressure and three cycles, the high-pressure homogenizer subjects the emulsion to extremely high shear force, cavitation, and impact force as it passes through the microchannels, thereby further refining the oil droplets to a more stable and uniform micron-sized range.

[0037] Step 5: Prepare a coconut oil emulsion loaded with lemon essential oil.

[0038] Mix 0.5 mol / L citric acid aqueous solution, chitosan and lecithin at a ratio of 100 mL: 3 g: 1 g to obtain a chitosan solution; Mix calcium chloride and deionized water at a ratio of 1g:20mL until homogeneous to obtain a calcium chloride solution; Weigh 2L of the homogeneous dispersion and add it to the reaction flask. Stir at 200rpm. Add 280mL of chitosan solution and citric acid to the reaction flask to adjust the pH of the system to 4. Stir for 20min. Add 200mL of calcium chloride solution dropwise to the reaction flask and stir for 6min. Reduce the temperature of the reaction flask to 5℃ and let it stand for 10h to obtain a coconut oil emulsion loaded with lemon essential oil.

[0039] In the reaction, chitosan, a cationic polysaccharide, undergoes amino protonation under acidic conditions, becoming positively charged. By adjusting the pH of the system to a weakly acidic state, the chitosan becomes completely positively charged. The negatively charged interface of carboxylated cellulose nanoparticles immediately undergoes electrostatic adsorption with chitosan. The stable oil droplet surface of carboxylated cellulose has a high negative potential, and chitosan molecules are strongly adsorbed to the oil droplet interface, forming the first composite film. After chitosan adsorption, the oil droplet surface changes from negatively charged to weakly positively charged, creating new charge repulsion between the droplets, thereby further inhibiting aggregation. After the calcium chloride solution is added, Ca... 2+ Simultaneously with induced interchain ionic crosslinking of chitosan, Ca 2+ It can react with the -NH3 on chitosan. + Through coordination or charge bridging with some hydroxyl groups, chitosan forms a denser network structure at the interface; Ca 2+It can also form metal bridges with the phosphate groups in lecithin, greatly improving the interfacial strength. During the curing process, the cross-linking reaction proceeds further, the interfacial film solidifies and forms a stable shell, making the oil droplet structure more complete and less susceptible to breakage due to shearing, impact or storage conditions.

[0040] Example 2

[0041] This embodiment provides a method for preparing a coconut oil emulsion loaded with lemon essential oil, specifically including the following steps: Step 1: Preparation of carboxylated cellulose nanoparticles Sodium hypochlorite and deionized water were mixed evenly at a ratio of 1g:5mL to obtain a sodium hypochlorite solution; Weigh out 10g of nanocellulose, 0.13g of TEMPO, and 1L of deionized water and add them to a high-speed homogenizer. Set the speed to 11000rpm and the homogenization time to 4min. Transfer the homogenate to a reaction flask and stir. Add 2.5mol / L sodium hydroxide solution to the reaction flask to adjust the pH of the system to 10.0. Cool the reaction flask to 23℃ and add 10mL of sodium hypochlorite solution dropwise. While adding the sodium hypochlorite solution, add 1.5mol / L sodium hydroxide solution dropwise to the reaction flask to maintain the pH of the system at 10.0. After the addition is complete, keep the reaction at this temperature for 105min. Add 20mL of sodium hydroxide solution to the reaction flask. An 8wt% sodium thiosulfate solution was prepared and placed in a dialysis bag with a molecular weight cutoff of 7000 Da. The dialysis bag was placed in deionized water, and the deionized water was changed every 6 hours. After dialysis for 48 hours, the material in the dialysis bag was transferred to a freeze dryer at -30℃ for freeze drying, and carboxylated nanocellulose with a molecular weight cutoff of >10000 Da was screened out.

[0042] Step 2: Prepare lemon essential oil packets and paste

[0043] Weigh out 85g of β-cyclodextrin and 1L of deionized water and add them to the reaction flask. Stir at 700rpm and raise the temperature of the reaction flask to 50℃. Stir until the system is dissolved and increase the stirring speed to 4500rpm. Add 10g of lemon essential oil dropwise to the reaction flask. After the addition is complete, stir and disperse for 13min. Cool the reaction solution to 6.5℃ and let it stand for 3.5h. Place the reaction solution in a centrifuge and set the centrifugation speed to 9500rpm. Centrifuge for 5min and skim off the upper layer of suspended free oil to obtain lemon essential oil packets and pulp.

[0044] Step 3: Prepare water-based mixed slurry and mixed coconut oil

[0045] Add sodium citrate to 0.1M citric acid to adjust the pH of the system to 6.0 to obtain citric acid buffer solution; Weigh 25g of carboxylated nanocellulose and 1L of citrate buffer into a high-speed homogenizer, set the speed to 11000rpm and the homogenization time to 4min. Transfer the homogenate to a reaction flask and stir, set the stirring speed to 1100rpm. Add 1L of lemon essential oil packet and slurry to the reaction flask and stir for 13min to obtain a water-based mixed slurry. Weigh out 40g of coconut oil and add it to the reaction flask. Heat the reaction flask to 33℃. After the coconut oil melts, add 5.4g of lemon essential oil, 0.02g of tocopherol and 0.2g of lecithin to the reaction flask. Stir for 13 minutes to obtain mixed coconut oil.

[0046] Step 4: Prepare homogeneous dispersion

[0047] Weigh 1.2L of water-based mixed slurry and add it to the reaction flask. Stir the slurry at 14000rpm. Cool the reaction flask to 33℃. Add 200g of mixed coconut oil to the reaction flask and emulsify and disperse for 3.5min. Cool the reaction liquid to 13℃. Transfer the emulsified slurry to a high-pressure homogenizer. Set the high-pressure homogenization pressure to 65MPa and the homogenization cycle to 3 times. Perform high-pressure homogenization to obtain a homogenized dispersion.

[0048] Step 5: Prepare a coconut oil emulsion loaded with lemon essential oil.

[0049] Mix 0.5 mol / L citric acid aqueous solution, chitosan and lecithin at a ratio of 100 mL: 3.5 g: 1.5 g to obtain a chitosan solution; Mix calcium chloride and deionized water at a ratio of 1g:20mL until homogeneous to obtain a calcium chloride solution; Weigh 2L of the homogeneous dispersion and add it to the reaction flask. Stir at 250rpm. Add 280mL of chitosan solution and citric acid to the reaction flask to adjust the pH of the system to 4.3. Stir for 25min. Add 200mL of calcium chloride solution to the reaction flask and stir for 7min. Lower the temperature of the reaction flask to 7.5℃ and let it stand for 11h to obtain a coconut oil emulsion loaded with lemon essential oil.

[0050] Example 3

[0051] This embodiment provides a method for preparing a coconut oil emulsion loaded with lemon essential oil, specifically including the following steps: Step 1: Preparation of carboxylated cellulose nanoparticles Sodium hypochlorite and deionized water were mixed evenly at a ratio of 1g:5mL to obtain a sodium hypochlorite solution; Weigh out 10g of nanocellulose, 0.15g of TEMPO, and 1L of deionized water and add them to a high-speed homogenizer. Set the speed to 12000rpm and the homogenization time to 5min. Transfer the homogenate to a reaction flask and stir. Add 3mol / L sodium hydroxide solution to the reaction flask to adjust the pH of the system to 10.5. Cool the reaction flask to 25℃ and add 10mL of sodium hypochlorite solution dropwise. While adding the sodium hypochlorite solution, add 2mol / L sodium hydroxide solution dropwise to the reaction flask to maintain the pH of the system at 10.5. After the addition is complete, keep the reaction at this temperature for 120min. Add 20mL of sodium hydroxide solution to the reaction flask. An 8wt% sodium thiosulfate solution was prepared and placed in a dialysis bag with a molecular weight cutoff of 7000 Da. The dialysis bag was placed in deionized water, and the deionized water was changed every 6 hours. After dialysis for 48 hours, the material in the dialysis bag was transferred to a freeze dryer at -30℃ for freeze drying, and carboxylated nanocellulose with a molecular weight cutoff of >10000 Da was screened out.

[0052] Step 2: Prepare lemon essential oil packets and paste

[0053] Weigh 90g of β-cyclodextrin and 1L of deionized water and add them to the reaction flask. Stir at 800rpm and raise the temperature of the reaction flask to 55℃. Stir until the system is dissolved and increase the stirring speed to 5000rpm. Add 10g of lemon essential oil to the reaction flask. After the addition is complete, stir and disperse for 15min. Cool the reaction solution to 8℃ and let it stand for 4h. Place the reaction solution in a centrifuge and set the centrifugation speed to 10000rpm. Centrifuge for 5min and skim off the upper layer of suspended free oil to obtain lemon essential oil packets and pulp.

[0054] Step 3: Prepare water-based mixed slurry and mixed coconut oil

[0055] Sodium citrate was added to 0.1M citric acid to adjust the pH of the system to 6.2, thus obtaining a citrate buffer solution. Weigh out 30g of carboxylated nanocellulose and 1L of citrate buffer and add them to a high-speed homogenizer. Set the speed to 12000rpm and the homogenization time to 5min. Transfer the homogenate to a reaction flask and stir. Set the stirring speed to 1200rpm. Add 1L of lemon essential oil packet and slurry to the reaction flask and stir for 15min to obtain a water-based mixed slurry. Weigh out 40g of coconut oil and add it to the reaction flask. Heat the reaction flask to 35℃. After the coconut oil melts, add 5.6g of lemon essential oil, 0.02g of tocopherol and 0.2g of lecithin to the reaction flask. Stir for 15 minutes to obtain mixed coconut oil.

[0056] Step 4: Prepare homogeneous dispersion

[0057] Weigh 1.4L of water-based mixed slurry and add it to the reaction flask. Stir the slurry at 15000rpm. Cool the reaction flask to 35℃. Add 200g of mixed coconut oil to the reaction flask and emulsify and disperse for 4min. Cool the reaction liquid to 15℃ and transfer the emulsified slurry to a high-pressure homogenizer. Set the high-pressure homogenization pressure to 70MPa and the homogenization cycle to 3 times. Perform high-pressure homogenization to obtain a homogenized dispersion.

[0058] Step 5: Prepare a coconut oil emulsion loaded with lemon essential oil.

[0059] Mix 0.5 mol / L citric acid aqueous solution, chitosan and lecithin at a ratio of 100 mL: 4 g: 2 g to obtain a chitosan solution; Mix calcium chloride and deionized water at a ratio of 1g:20mL until homogeneous to obtain a calcium chloride solution; Weigh 2L of the homogeneous dispersion and add it to the reaction flask. Stir at 300rpm. Add 280mL of chitosan solution to the reaction flask and add citric acid to adjust the pH of the system to 4.5. Stir for 30min. Add 200mL of calcium chloride solution dropwise to the reaction flask and stir for 8min. Lower the temperature of the reaction flask to 10℃ and let it stand for 12h to obtain a coconut oil emulsion loaded with lemon essential oil.

[0060] Comparative Example 1

[0061] The difference between this comparative example and Example 3 is that step 1 is omitted, and the carboxylated nanocellulose in step 3 is replaced with nanocellulose.

[0062] Comparative Example 2

[0063] The difference between this comparative example and Example 3 is that step 2 is omitted, and lemon essential oil packets and pulp are not added in step 3.

[0064] Comparative Example 3

[0065] The difference between this comparative example and Example 3 is that step 5 is omitted, and the homogeneous dispersion prepared in step 4 is used as the finished coconut oil emulsion loaded with lemon essential oil.

[0066] Performance testing: The particle size of the emulsified particles in the coconut oil emulsion samples loaded with lemon essential oil prepared in Examples 1-3 and Comparative Examples 1-3 was determined according to the standard GB / T 29022-2021 "Particle size analysis by dynamic light scattering (DLS)". The coconut oil emulsion samples loaded with lemon essential oil prepared in Examples 1-3 and Comparative Examples 1-3 were placed at room temperature for 21 days. Then, the instability index of the coconut oil emulsion samples loaded with lemon essential oil before and after storage was determined according to the standard GB / T 38431-2019 "Stability Evaluation of Particulate Dispersion Systems - Static Multiple Light Scattering Method". The specific test data are shown in Table 1 below.

[0067] Table 1 - Performance Test Data of Samples

[0068] Data Analysis: Comparative analysis of the data in Table 1 above shows that the particle size of the emulsion particles in the coconut oil emulsion loaded with lemon essential oil prepared by this invention reaches 1.61±0.03μm, the instability index of the emulsion is reduced to 0.003±0.001, and after 21 days of storage, the instability index of the emulsion remains at 0.005±0.001. All performance test data are better than those of the comparative example.

[0069] The coconut oil emulsion loaded with lemon essential oil prepared in Example 3 was applied to the preparation of cake baking test samples. The cake prepared by using the whole coconut oil instead of the coconut oil emulsion loaded with lemon essential oil was used as a control sample for comparison. The texture and sensory evaluation of the prepared cakes were carried out. The specific test data are shown in Table 2-3 below.

[0070] Table 2 - Texture test data of the samples

[0071] Table 3 - Sensory evaluation data of the samples

[0072] Data Analysis: Comparative analysis of the data in Tables 2-3 shows that the coconut oil emulsion loaded with lemon essential oil prepared in this invention, when used to prepare test samples for cake baking, exhibited significantly higher hardness, bite-likeness, and chewiness than the control sample in the all-oil group. This indicates that the emulsion can form a more stable porous structure during baking, enhancing the mechanical support of the cake and making the texture more solid and layered. Its elasticity and cohesion were basically consistent with the control, indicating that the emulsion substitution did not disrupt the foam structure and internal continuity of the batter. Sensory evaluation showed that the two groups were generally similar in terms of color, appearance, and texture, while the test sample scored slightly higher in taste. This reflects that the dual-carrier structure of "included and free" lemon essential oil designed in this invention can achieve a more lasting and gentler release of lemon flavor, giving the final product better flavor quality. This effectively improves the texture of the cake and optimizes some sensory attributes while maintaining overall quality.

[0073] This invention describes a process involving the construction of an aqueous phase structure using carboxylated cellulose nanoparticles, the encapsulation of lemon essential oil with β-cyclodextrin to enhance flavor stability, the formation of fine emulsion droplets through high-pressure homogenization of the structured oil phase, and further utilizing chitosan-lecithin-Ca... Polyelectrolyte networks are used to immobilize emulsion droplets, thereby producing a loaded coconut oil emulsion with small particle size, high stability, and excellent flavor retention. This emulsion has been successfully applied in cake baking to improve the texture and flavor of the cake.

[0074] The preferred embodiments of the present invention disclosed above are merely illustrative of the invention. These preferred embodiments do not exhaustively describe all details, nor do they limit the invention to specific implementations. Clearly, many modifications and variations can be made based on the content of this specification. This specification selects and specifically describes these embodiments to better explain the principles and practical applications of the invention, thereby enabling those skilled in the art to better understand and utilize the invention. The invention is limited only by the claims and their full scope and equivalents.

Claims

1. A method for preparing a coconut oil emulsion loaded with lemon essential oil, characterized in that, Includes the following steps: S1. Mix carboxylated nanocellulose and citrate buffer solution and homogenize. Add lemon essential oil packet and slurry to the reaction system and stir for 10-15 min to obtain water-based mixed slurry. S2. Heat the coconut oil to 30-35℃ until melted, then add lemon essential oil, tocopherol and lecithin, mix and stir for 10-15 minutes to obtain mixed coconut oil; S3. Under high-speed stirring, add the mixed coconut oil to the water-based slurry at a temperature of 30-35℃, emulsify and mix for 3-4 minutes, transfer the slurry to a high-pressure homogenizer for high-pressure homogenization to obtain a homogenized dispersion. S4. While stirring, add chitosan solution to the homogeneous dispersion, add citric acid to the reaction system, adjust the pH of the system to 4-4.5, stir for 20-30 min, add calcium chloride solution dropwise to the reaction system, stir for 6-8 min, lower the temperature of the reaction system to 5-10℃, and let it stand for 10-12 h to obtain a coconut oil emulsion loaded with lemon essential oil.

2. The method for preparing a coconut oil emulsion loaded with lemon essential oil according to claim 1, characterized in that, In step S1, the ratio of carboxylated nanocellulose, citrate buffer, and lemon essential oil package and pulp is 2-3g:100mL:100mL. The citrate buffer is composed of 0.1M citric acid and sodium citrate, with a pH of 5.8-6.

2.

3. The method for preparing a coconut oil emulsion loaded with lemon essential oil according to claim 1, characterized in that, In step S2, the weight ratio of coconut oil, lemon essential oil, tocopherol and lecithin is 20:2.6-2.8:0.01:0.

1.

4. The method for preparing a coconut oil emulsion loaded with lemon essential oil according to claim 1, characterized in that, In step S3, the high-speed stirring speed is 13000-15000 rpm, and the oil-to-water ratio of the mixed coconut oil and water-based slurry is 1:5-7; in step S4, the stirring speed is 200-300 rpm, and the volume ratio of the homogeneous dispersion, chitosan solution, and calcium chloride solution is 500:70:

50. The chitosan solution is composed of 0.5 mol / L citric acid aqueous solution, chitosan, and lecithin at a ratio of 100 mL:3-4 g:1-2 g, and the calcium chloride solution is composed of calcium chloride and deionized water at a ratio of 1 g:20 mL.

5. The method for preparing a coconut oil emulsion loaded with lemon essential oil according to claim 1, characterized in that, The preparation method of carboxylated cellulose nanoparticles is as follows: cellulose nanoparticles, TEMPO, and deionized water are mixed and homogenized. Sodium hydroxide solution is added to the reaction system to adjust the pH to 9.5-10.

5. The reaction system is cooled to 20-25℃, and sodium hypochlorite solution is added dropwise to the reaction system. While adding sodium hypochlorite solution, sodium hydroxide solution is added dropwise to the reaction system to maintain the pH at 9.5-10.

5. After the addition is complete, the reaction is kept at this temperature for 90-120 min. After post-treatment, carboxylated cellulose nanoparticles with a molecular weight greater than 10000 Da are obtained.

6. The method for preparing a coconut oil emulsion loaded with lemon essential oil according to claim 5, characterized in that, The ratio of the amount of nanocellulose, TEMPO, deionized water, and sodium hypochlorite solution is 10g:0.1-0.15g:1L:10mL, and the sodium hypochlorite solution is composed of sodium hypochlorite and deionized water at a ratio of 1g:5mL.

7. The method for preparing a coconut oil emulsion loaded with lemon essential oil according to claim 1, characterized in that, The preparation method of lemon essential oil packets and pulp is as follows: β-cyclodextrin and deionized water are mixed and stirred. The temperature of the reaction system is raised to 45-55℃ and stirred until the system is dissolved. The stirring speed is increased to 4000-5000 rpm. Lemon essential oil is added dropwise to the reaction system. After the addition is completed, the mixture is stirred and dispersed for 10-15 minutes. After post-processing, lemon essential oil packets and pulp are obtained.

8. The method for preparing a coconut oil emulsion loaded with lemon essential oil according to claim 7, characterized in that, The ratio of β-cyclodextrin, deionized water, and lemon essential oil is 8-9g:100mL:1g.

9. A coconut oil emulsion loaded with lemon essential oil, characterized in that, The coconut oil emulsion loaded with lemon essential oil is prepared by the method for preparing a coconut oil emulsion loaded with lemon essential oil as described in any one of claims 1-8.

10. An application of a coconut oil emulsion loaded with lemon essential oil, characterized in that, The coconut oil emulsion loaded with lemon essential oil prepared by the method of any one of claims 1-8 is applied to the processing of baked goods to enhance the flavor and nutritional value of baked goods.

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