A functional lipid-rich emulsion gel and its enzymatic preparation method and use

Abstract

This invention discloses a functional lipid-rich emulsion gel, its enzymatic preparation method, and its application, belonging to the field of functional foods and food processing technology. Utilizing the combined emulsifying ability and transesterification catalytic activity of gliadin-sodium carboxymethyl cellulose-lipase ternary composite nanoparticles, an emulsion gel rich in medium- and long-chain triglycerides (MLCTs) is obtained through a one-step in-situ enzymatic transesterification process in a mixture of vegetable oil, coconut oil, and water, without the need for enzyme and product separation and purification. This strategy maximizes the preservation of the nutritional and flavor characteristics of MLCTs while avoiding the poor compatibility between MLCTs synthesized alone and the emulsion gel system, ensuring the stability of the emulsion gel. When this emulsion gel is applied to baked goods, it can replace part or all of the butter, achieving lipid nutritional reconstruction while synergistically forming a porous and crisp structure, maintaining both the natural coconut flavor and ideal texture of the product.

Description

Technical Field

[0001] This invention belongs to the field of functional food and food processing technology, specifically relating to a functional lipid-rich emulsion gel, its enzymatic preparation method, and its application. Background Technology

[0002] Fat plays a crucial role in baked goods systems; however, animal fats or hydrogenated vegetable oils widely used in traditional baking are rich in saturated fatty acids. Long-term intake can significantly increase the risk of cardiovascular disease, obesity, and other chronic diseases, which contradicts current health-conscious consumption trends. Therefore, developing low-fat, low-saturated-fat alternative oils that also maintain the quality of baked goods has become a research hotspot in the baking industry.

[0003] Currently, various fat substitution strategies have emerged in the industry, mainly including plant-based oil substitution, and the addition of dietary fiber or protein-based fat substitutes. However, their practical applications have significant limitations: 1. Limited nutritional improvement. Existing fat substitution strategies mostly optimize from the perspective of reducing fat content or replacing fat sources, failing to regulate the nutritional characteristics of oils at the structural level of lipid molecules, and thus unable to fundamentally solve the nutritional deficiencies of traditional oils; 2. Poor processing stability and product texture. Fat plays a crucial role in biscuit baking, such as lubrication and crisping. Existing substitutes often cannot simulate the processing characteristics of traditional oils, resulting in problems such as dryness, hardness, and insufficient crispness in the substituted finished product. Furthermore, under high-temperature baking conditions, demulsification and oil leakage are prone to occur, severely affecting the product's appearance, taste, and processing qualification rate; 3. Poor flavor harmony. Most existing fat substitutes have a single flavor profile, failing to impart the richness of traditional biscuit oils, and may even introduce off-flavors such as the beany taste of plant proteins, ruining the overall flavor of the biscuit. Therefore, how to achieve low-fat baking products while also ensuring good taste, high-temperature processing stability, and giving them a natural and pleasant flavor remains a pressing technical challenge.

[0004] Medium- and long-chain triglycerides (MLCTs), as functional structural lipids, possess various physiological functions such as reducing body fat accumulation and improving lipid metabolism. Furthermore, their physicochemical properties are compatible with traditional baking fats, making them an ideal alternative substrate. However, the practical application of MLCTs in the baking field faces two major challenges. First, enzymatically synthesized MLCTs are typically liquid or semi-solid at room temperature, lacking the plasticity and solid skeletal support of traditional baking fats. Direct addition cannot form an effective gluten-fat layered structure, easily leading to a flat and greasy finished product.

[0005] Emulsion gels can improve the stability of emulsion mixtures and, through their gel network structure, mimic the plasticity and lubrication of traditional fats, showing great potential for application in the field of fat substitution. However, the gel matrix of conventional emulsion gels is mainly composed of single or binary complex components such as proteins and polysaccharides. These matrices can only play a network support role and lack catalytic activity, making it impossible to achieve in-situ structural modification and functionalization of lipid molecules. Consequently, it is difficult to simultaneously address the multiple issues of nutrition, texture, and flavor in low-fat baked goods.

[0006] Given the technical bottlenecks of existing fat substitutes in terms of nutritional structure, processing stability, and flavor harmony, providing a fat substitute with high nutritional value, excellent processing performance, and natural flavor characteristics, as well as its preparation method, has become an urgent technical problem to be solved in this field. Summary of the Invention

[0007] To address the shortcomings of existing technologies, this invention develops a gel matrix composed of a ternary composite nanoparticle of gliadin (Gli), sodium carboxymethyl cellulose (CMC), and lipase (Lip). This matrix is ​​then compounded with vegetable oil / coconut oil to simultaneously induce in-situ synthesis and emulsion gelation of MLCT, resulting in a food-grade emulsion gel rich in functional lipids. Furthermore, this invention provides an application scheme for this food-grade emulsion gel rich in functional lipids in low-fat baked goods, synergistically enhancing the nutritional functionality, processing suitability, and natural flavor of baked goods. This addresses the technical challenges of texture degradation and reliance on artificial flavorings in traditional low-fat baked goods, thus providing a new pathway for the research and production of healthy baked foods.

[0008] To achieve the above objectives, this invention employs an integrated construction strategy based on "interfacial biocatalysis-in-situ utilization": First, a ternary composite gel matrix (Gli-CMC-Lip) with catalytic activity is constructed, consisting of gliadin (Gli), sodium carboxymethyl cellulose (CMC), and lipase (Lip). Next, using a mixture of vegetable oil and coconut oil as the oil phase and reaction substrate, emulsion gelation and in-situ synthesis of medium- and long-chain triglycerides (MLCT) are simultaneously achieved through homogenization emulsification and controlled enzymatic reaction. Finally, this emulsion gel, rich in MLCT and retaining the natural coconut flavor, is used as a fat substitute in biscuit production to obtain a novel low-fat biscuit that combines nutritional reconstruction and sensory quality.

[0009] The present invention adopts the following technical solution: First, it provides an enzymatic preparation method for emulsion gels rich in functional lipids, specifically including the following steps.

[0010] (1) Preparation of ternary composite nanoparticle dispersion

[0011] Glycol protein was dissolved in an aqueous ethanol solution to obtain a glycol protein stock solution, and sodium carboxymethyl cellulose was dissolved in water to obtain a sodium carboxymethyl cellulose stock solution. Under stirring conditions, the glycol protein stock solution was slowly added dropwise to the sodium carboxymethyl cellulose stock solution to remove ethanol and obtain a Gli-CMC dispersion. An aqueous solution of lipase was added to the Gli-CMC dispersion and stirred at low temperature to allow the lipase to adsorb onto the particle surface, thus obtaining a Gli-CMC-Lip ternary composite nanoparticle dispersion.

[0012] (2) Preparation of food-grade emulsion gels rich in functional lipids A mixture of vegetable oil rich in long-chain fatty acids and coconut oil was used as the oil phase, and a dispersion of Gli-CMC-Lip ternary composite nanoparticles was used as the aqueous phase gel matrix to form a homogenized emulsion gel. The Gli-CMC-Lip ternary composite nanoparticles in the system were used to perform an enzymatic transesterification catalytic reaction to obtain an emulsion gel rich in MLCT. After the reaction was completed, the system was heated to inactivate lipase, the reaction was terminated, and after cooling, a stable food-grade emulsion gel rich in functional lipids was obtained.

[0013] Preferably, in step (1), the ethanol aqueous solution has an ethanol volume fraction of 70%; the gliadin stock solution has a gliadin concentration of 10.0 wt%; the sodium carboxymethyl cellulose stock solution has a sodium carboxymethyl cellulose concentration of 0.5 wt%; when the gliadin stock solution is slowly added dropwise to the sodium carboxymethyl cellulose stock solution, the mass ratio of gliadin to sodium carboxymethyl cellulose is required to be 2:1 to 8:1, preferably 4:1; the lipase aqueous solution has a lipase concentration of 20 to 100 mg / mL, preferably 80 mg / mL; when the lipase aqueous solution is added to the Gli-CMC dispersion, the volume ratio of the lipase aqueous solution to the Gli-CMC dispersion is required to be 1:1 to 1:5, preferably 1:3; the low-temperature stirring conditions are an ice-water bath, a stirring speed of 600 rpm, and a time of 1 to 3 hours.

[0014] Preferably, the Gli-CMC-Lip ternary composite nanoparticles described in step (1) have a three-phase contact angle of 84.19° and a potential of [missing value] when the mass ratio of Gli to CMC is 4:1. At 36.749 mV, the particles possess suitable interfacial wettability and stability, enabling them to irreversibly adsorb and anchor at the oil-water interface to form a dense particle adsorption layer.

[0015] Preferably, the lipase in step (1) is selected from one or more of Candida columnar lipase CRL, Yersinia lipase AYS, Pseudomonas cepacia lipase PS and Candida columnar lipase CSL, and preferably Pseudomonas cepacia lipase PS.

[0016] Preferably, the vegetable oil rich in long-chain fatty acids in step (2) is selected from one or more of flaxseed oil, rapeseed oil, corn oil, soybean oil, sunflower oil or peanut oil; the mass ratio of the vegetable oil rich in long-chain fatty acids to coconut oil is 1:9 to 9:1; the volume ratio of the oil phase to the aqueous phase gel matrix is ​​preferably 7:3; the homogenization speed is 8000 to 15000 rpm and the time is 1 to 3 min.

[0017] Preferably, the temperature of the enzymatic transesterification catalytic reaction in step (2) is 40~80℃ and the time is 0~30min; the temperature of the inactivation of lipase is 80~100℃ and the time is 5~15min.

[0018] In basic application scenarios where lipid remodeling requirements are not high, the time for enzymatic transesterification catalysis is 0 min, meaning that enzymatic transesterification catalysis is not required. The initial emulsion gel matrix that has not undergone sufficient transesterification can be directly used for premixing baking dough. It can also achieve partial physical substitution of butter by virtue of its protein-polysaccharide interface film and gel structure.

[0019] Preferably, the emulsion gel in step (2) is a particle-stabilized oil-in-water emulsion gel with an average droplet size of 11.96 μm to 23.46 μm. The emulsion gel has a supporting structure, and its rheological characteristics in the scanning frequency range of 1 to 100 rad / s show that its storage modulus (G') is always greater than its loss modulus (G″). When the mass ratio of Gli to CMC is 4:1 and the oil-water ratio is 7:3, the average droplet size is 11.96 μm, and G' is between 100 and 200 Pa. At this time, the nanoparticles are densely arranged at the oil-water interface of the dispersed phase droplets, constructing an interfacial film that has both emulsion stabilization and enzymatic catalytic activity.

[0020] Secondly, the present invention also provides an application of the food-grade emulsion gel rich in functional lipids prepared by the above method in baking, characterized in that the specific steps are as follows: the food-grade emulsion gel rich in functional lipids is mixed with butter in any proportion and then whipped to obtain an oil mixture; the oil mixture is mixed with other raw materials to form a dough, and after the dough is shaped, it is baked to obtain the final product.

[0021] Preferably, the whipping time is 1.5 to 2 minutes; the specific mass ratio of the oil mixture to other ingredients is 8 to 12 parts oil mixture, 45 to 55 parts low-gluten flour, 0.4 to 0.8 parts salt, 0.4 to 0.8 parts yeast, 0.2 to 0.4 parts baking soda, and 15 to 20 parts milk.

[0022] Preferably, the baking temperature is 160~200℃, the in-situ constructed emulsion gel network and the butter mixture support the skeleton in the dough, the coconut oil component releases natural aroma and forms a porous and crisp structure as the water evaporates.

[0023] The volatile flavor characteristics of the final product meet the following parameters: Detected by a PEN3 electronic nose containing a metal oxide semiconductor sensor, the response value of the sensor W1W, which is sensitive to sulfur compounds, is 5.30~5.53, and the response value of the sensor W2S, which is sensitive to alcohols and some aromatic compounds, is 1.26~1.32; further principal component analysis shows that the final product has the natural coconut aroma volatile flavor characteristics formed by the directional release of coconut oil components from the emulsion gel, with a flavor retention rate greater than 90%.

[0024] In summary, this invention provides a method for the simultaneous preparation of food-grade emulsion gels rich in functional lipids based on interfacial enzymatic catalysis and its application in baking. Compared with the prior art, this invention has the following significant advantages: (1) This invention utilizes a ternary composite nanoparticle dispersion loaded with lipase as both an emulsifier and a catalyst to achieve the simultaneous rapid in-situ synthesis of MLCT and the construction of an emulsion gel network. This strategy can significantly shorten the preparation cycle and reduce production energy consumption and costs.

[0025] (2) The emulsion gel prepared by this invention has good compatibility with the gluten protein backbone. Experimental verification shows that when this emulsion gel is used to partially replace butter in the preparation of biscuits, the product's key quality indicators, such as hardness, crispness, and golden baking color, are close to those of products made entirely with butter. This successfully solves the common industry problem of poor taste, deteriorated texture, and decreased sensory quality of baked goods that is prevalent in the application of traditional fat substitutes.

[0026] (3) This invention cleverly uses natural coconut oil as a reaction substrate. The enzyme and product do not need to be separated and purified. MLCT effectively preserves the unique natural flavor of coconut oil, while masking the off-flavors that may exist in the protein matrix, thus improving the sensory quality of low-fat food. Attached Figure Description

[0027] 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 will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0028] Figure 1Scanning electron microscope images of gliadin nanoparticles (Gli), gliadin-carboxymethyl cellulose sodium composite nanoparticles (Gli-CMC), and gliadin-carboxymethyl cellulose sodium-lipase ternary complex (Gli-CMC-Lip), scale bar: 500 nm.

[0029] Figure 2 Visual image, optical microscope image (scale bar: 100 μm), and cryo-scanning electron microscope image (scale bar: 20 μm) of the Gli-CMC-Lip stabilized emulsion gel.

[0030] Figure 3 The images show the emulsion gel / butter mixtures of Examples 1-3 and Comparative Examples 1-2.

[0031] Figure 4 These are visual representations of the baked products from Examples 1-3 and Comparative Examples 1-2.

[0032] Figure 5 The images show cross-sectional scanning electron microscope images of baked goods from Examples 1-3 and Comparative Examples 1-2.

[0033] Figure 6 The electronic nose flavor characterization diagrams are for the products of Examples 1, 2 and Comparative Example 1. Detailed Implementation

[0034] 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.

[0035] The term "embodiment" used herein, as an example, is not necessarily to be construed as superior to or better than other embodiments. Performance testing in the embodiments of this application, unless otherwise specified, employs conventional testing methods in the art. It should be understood that the terminology used in this application is merely for describing particular implementations and is not intended to limit the scope of this disclosure.

[0036] Unless otherwise stated, the technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains; other experimental methods and technical means not specifically mentioned herein refer to experimental methods and technical means commonly used by one of ordinary skill in the art.

[0037] To better illustrate the content of this application, numerous specific details are provided in the following detailed embodiments. Those skilled in the art should understand that this application can be implemented even without certain specific details. In the embodiments, some methods, means, instruments, and devices well-known to those skilled in the art are not described in detail in order to highlight the main points of this application.

[0038] Without conflict, the technical features disclosed in the embodiments of this application can be combined arbitrarily, and the resulting technical solution belongs to the content disclosed in the embodiments of this application.

[0039] It should be noted that the MLCT synthesized by the food-grade emulsion gel catalysis stabilized by gliadin-sodium carboxymethyl cellulose-lipase composite nanoparticles was detected by gas chromatography. The gas chromatography detection conditions were as follows: the chromatographic column was a DB-5HT (15m × 0.320 mm, 0.10 μm), and the detector was an FID detector. The column was held at 170°C for 2 min, and then the temperature was increased to 380°C at a rate of 5°C / min and held for another 6 min. Subsequently, the sample was injected at a split ratio of 1:50. The carrier gas was helium at a flow rate of 2 mL / min, and the air flow rate was 200 mL / min. The temperature of the injector and detector was 380°C.

[0040] Example 1 1. Preparation method of food-grade emulsion gel rich in functional lipids (1) Preparation of ternary composite nanoparticle dispersion Glycol protein was dissolved in a 70% (v / v) aqueous ethanol solution to prepare a 10.0 wt% glycol protein stock solution. Sodium carboxymethyl cellulose was dissolved in deionized water and stirred overnight at 25°C to prepare a 0.5 wt% sodium carboxymethyl cellulose stock solution.

[0041] Under stirring conditions, gliadin stock solution was slowly added dropwise to sodium carboxymethyl cellulose stock solution at a mass ratio of 4:1. The mixture was then placed in a rotary evaporator and distilled under reduced pressure at 40°C to completely remove ethanol, obtaining Gli-CMC dispersion. An aqueous solution of Pseudomonas cepacia lipase PS was added to the Gli-CMC dispersion at a volume ratio of 3:1, and the mixture was stirred continuously at 600 rpm for 2 hours in an ice-water bath to allow the lipase to adsorb onto the particle surface, resulting in Gli-CMC-Lip ternary composite nanoparticle dispersion.

[0042] Scanning electron microscope images of gliadin nanoparticles (Gli), gliadin-sodium carboxymethyl cellulose composite nanoparticles (Gli-CMC), and gliadin-sodium carboxymethyl cellulose-lipase ternary complex (Gli-CMC-Lip) are shown below. Figure 1 As shown, Gli forms smooth spherical nanoparticles; Gli-CMC maintains a spherical framework but is accompanied by a certain degree of particle adhesion; Gli-CMC-Lip further forms a highly interconnected network structure, indicating that the lipase is deeply embedded in the Gli-CMC network.

[0043] The zeta potential of Gli-CMC-Lip was measured using a Zetasizer Pro (Malvern Panalytical); the contact angle of Gli-CMC-Lip was measured using a contact angle measuring instrument (SDC-200SA) and the contact angle θ was fitted using the accompanying software. w / o The three-phase contact angle of the Gli-CMC-Lip prepared in this embodiment was tested to be 84.19°; its Zeta potential was... 36.749mV.

[0044] (2) Preparation of food-grade emulsion gels rich in functional lipids A mixture of flaxseed oil and coconut oil (mass ratio 3:7) was used as the oil phase, and the Gli-CMC-Lip ternary composite nanoparticle dispersion from step (1) was used as the aqueous gel matrix. The aqueous and oil phases were mixed in a volume ratio of 3:7, and the mixture was homogenized at 12000 rpm for 1 min using a handheld homogenizer to prepare an emulsion gel. The Gli-CMC-Lip ternary composite nanoparticles in the system were used to perform an enzymatic transesterification catalytic reaction at 60℃ for 15 min to obtain an emulsion gel rich in MLCT. After the reaction was completed, the system was heated in an 85℃ water bath for 10 min to inactivate lipase, and the reaction was terminated. After cooling, a stable food-grade emulsion gel rich in functional lipids was obtained. 50 µL of the emulsion was dispersed in 1 mL of n-hexane using a pipette, filtered through a 0.22 µm pore size filter membrane, and analyzed by gas chromatography. The MLCT yield reached 72.81%.

[0045] Visual image, optical microscope image (scale bar: 100 μm), and cryo-scanning electron microscope image of Gli-CMC-Lip stabilized emulsion gel are shown below. Figure 2As shown in the diagram, the resulting emulsion gel is milky white, fine, and solid-like, exhibiting excellent self-supporting properties as it does not flow when inverted. Optical microscopy images reveal that the emulsion droplets are regularly spherical, approximately 11.96 μm in size, spatially uniform, and with clear boundaries between droplets. No droplet aggregation, flocculation, or stratification was observed, indicating that the ternary composite particles provide good physical stability at the macroscopic level. Further observation using cryo-scanning electron microscopy revealed a dense and uniform microstructure with small, uniformly distributed pores and thick, intact pore walls. The Gli-CMC-Lip ternary composite nanoparticles are not only highly efficient interfacial emulsifiers but also key structural units for constructing a homogeneous three-dimensional network framework, endowing the emulsion with excellent structural integrity through interfacial reinforcement and spatial cross-linking.

[0046] Rheological tests were performed using a rotational rheometer (AR-2000ex) at 25°C within a scanning frequency range of 1–100 rad / s. The resulting oil-in-water emulsion gels all exhibited significantly higher G′ values ​​than G″, demonstrating gel behavior. The G′ values ​​ranged from 100 to 200 Pa, which corresponds to their relatively small droplet size.

[0047] 2. Application of food-grade emulsion gels rich in functional lipids in baking Mix 10 parts by weight of the fat (including 2.5 parts by weight of food-grade emulsion gel rich in functional lipids and 7.5 parts by weight of softened butter) and beat for 2 minutes. Then add 50 parts by weight of sifted low-gluten flour, 0.6 parts by weight of salt, 0.6 parts by weight of yeast, 0.3 parts by weight of baking soda and 20 parts by weight of milk and mix well to form a dough. Press the dough into a dough sheet and then press it into cookie dough using a mold. After cooling, place it in the oven and bake at 170°C (top heat) and 170°C (bottom heat) for 15 minutes.

[0048] Observe the mixture of emulsion gel and butter ( Figure 3 It was found that the mixture had a uniform color and good fusion, exhibiting a uniform and delicate "feather-like" structure, which demonstrated the system's good self-supporting ability at this ratio, which is very beneficial for the subsequent mixing of other dry components.

[0049] The overall color of the finished cookies Figure 4 The results were kept within a visually pleasing and acceptable range. (Cross-sectional scanning electron microscopy results) Figure 5 This indicates that the biscuit largely retains a continuous porous structure; although the pore size is slightly smaller than that of the all-butter control group, it still maintains intact pore walls. A PEN3 type electronic nose was used (…). Figure 6Flavor characterization showed that the volatile flavor of the product in this embodiment closely approximated the distribution area of ​​pure coconut oil in the PCA diagram. Analysis of the corresponding raw sensor data showed that the response value of sensor W1W, sensitive to sulfur compounds, reached 5.53, while the response value of sensor W2S, sensitive to alcohols and some aromatic compounds, was 1.32. The results indicate that by introducing an emulsion gel, the product successfully achieved a directional flavor reconstruction from the traditional butter biscuit aroma to a distinctly natural coconut aroma.

[0050] Texture analyzer tests (Table 1) showed that the biscuits of this embodiment had a hardness of 68013.33±11095.3 g, an adhesiveness of 0.18±0.04, an elasticity of 0.47±0.09 mm, a stickiness of 12890.00±4824.44 g, and a chewiness of 6.35±3.34 mJ. The data indicate that, under conditions of moderate substitution, this embodiment not only achieved the reconstruction of lipid nutrition but also preserved, to the greatest extent possible, the crisp texture and processing quality close to that of whole butter products.

[0051] Example 2 1. Preparation method of food-grade emulsion gel rich in functional lipids Same as Example 1.

[0052] 2. Application of food-grade emulsion gels rich in functional lipids in baking Mix 10 parts by weight of the fat (including 5 parts by weight of food-grade emulsion gel rich in functional lipids and 5 parts by weight of softened butter) and beat for 2 minutes. Then add 50 parts by weight of sifted low-gluten flour, 0.6 parts by weight of salt, 0.6 parts by weight of yeast, 0.3 parts by weight of baking soda and 20 parts by weight of milk and mix well to form a dough. Press the dough into a dough sheet and then press it into cookie dough using a mold. After cooling, place it in the oven and bake at 170°C (top heat) and 170°C (bottom heat) for 15 minutes.

[0053] The mixture is similar to that in Example 1 ( Figure 3 The color is uniform and well-blended, maintaining a delicate "wavy" structure and excellent self-supporting ability.

[0054] Senses and Microstructure Figure 4 , Figure 5 , Figure 6The results show that as the substitution ratio increases, the color of the finished biscuits is slightly darker than in Example 1, but the overall color remains within a visually pleasing and acceptable range. The microstructure also retains a continuous porous structure without skeletal collapse. Electronic nose detection shows that the sample points in this example also exhibit a significant rightward shift (coconut oil region) in the PCA plot. Among specific sensor response values, W1W is 5.30 and W2S is 1.26. This confirms that at this substitution ratio, the product begins to exhibit the volatile characteristics of natural coconut aroma, with a flavor retention rate greater than 90%.

[0055] The results of the texture analyzer test (Table 1) show that the hardness is 63393.33±3554.30 g, the adhesion is 0.19±0.04, the elasticity is 0.48±0.04 mm, the adhesiveness is 11986.67±2662.51 g, and the chewiness is 5.77±1.71 mJ. Although the various texture parameters are slightly lower than those of the control group, the overall mechanical strength remains stable, proving that the substitution ratio scheme has significant advantages.

[0056] Example 3 1. Preparation method of food-grade emulsion gel rich in functional lipids Same as Example 1.

[0057] 2. Application of food-grade emulsion gels rich in functional lipids in baking Mix 10 parts by weight of the fat (including 7.5 parts by weight of food-grade emulsion gel rich in functional lipids and 2.5 parts by weight of softened butter) and beat for 2 minutes. Then add 50 parts by weight of sifted low-gluten flour, 0.6 parts by weight of salt, 0.6 parts by weight of yeast, 0.3 parts by weight of baking soda and 20 parts by weight of milk and mix well to form a dough. Press the dough into a dough sheet and then press it into cookie dough using a mold. After cooling, place it in the oven and bake at 170°C (top heat) and 170°C (bottom heat) for 15 minutes.

[0058] Intuitive diagram ( Figure 4 The results showed that at high substitution ratios, the overall color of the sample darkened significantly, exhibiting excessive and undesirable browning, accompanied by increased surface roughness and shrinkage of the macrostructure. Cross-sectional scanning electron microscopy (SEM) revealed... Figure 5 The data shows that the porosity has further tightened, corresponding to macroscopic structural shrinkage and texture deterioration.

[0059] The texture analyzer test results (Table 1) show that the hardness decreased significantly to 49180.00±5634.63 g, the elasticity decreased to 0.39±0.02 mm, and the adhesiveness decreased to 6526.67±1099.29 g. The data confirm that the high substitution ratio led to a weakening of the continuous support skeleton, forming a discontinuous microstructure, weakening local mechanical strength and destroying the overall structural integrity, making it difficult to maintain a stable stress state during simulated chewing.

[0060] Example 4 1. Preparation method of food-grade emulsion gel rich in functional lipids (1) Preparation of ternary composite nanoparticle dispersion Same as Example 1.

[0061] (2) Preparation of food-grade emulsion gels rich in functional lipids A mixture of flaxseed oil and coconut oil (mass ratio 1:9) was used as the oil phase, and the Gli-CMC-Lip ternary composite nanoparticle dispersion from step (1) was used as the aqueous gel matrix. The aqueous and oil phases were mixed in a volume ratio of 3:7. The emulsion gel was prepared by homogenizing at 12000 rpm for 1 min using a handheld homogenizer. The Gli-CMC-Lip ternary composite nanoparticles in the system were used to perform an enzymatic transesterification catalytic reaction at 60℃ for 15 min to obtain an emulsion gel rich in MLCT. After the reaction was completed, the system was heated in an 85℃ water bath for 10 min to inactivate lipase and terminate the reaction. After cooling, a stable food-grade emulsion gel rich in functional lipids was obtained. 50 µL of the emulsion was dispersed in 1 mL of n-hexane using a pipette, filtered through a 0.22 µm pore size filter membrane, and analyzed by gas chromatography. The MLCT yield reached 65.03%.

[0062] Characterized using the same test methods as in Example 1, the system exhibited typical emulsion-gel characteristics (G'>G''), and the average droplet size fell within the effective range of 11.96 μm to 23.46 μm.

[0063] Example 5 1. Preparation method of food-grade emulsion gel rich in functional lipids (1) Preparation of ternary composite nanoparticle dispersion Same as Example 1.

[0064] (2) Preparation of food-grade emulsion gels rich in functional lipids A mixture of flaxseed oil and coconut oil (mass ratio 5:5) was used as the oil phase, and the Gli-CMC-Lip ternary composite nanoparticle dispersion from step (1) was used as the aqueous gel matrix. The aqueous and oil phases were mixed in a volume ratio of 3:7. The emulsion gel was prepared by homogenizing at 12000 rpm for 1 min using a handheld homogenizer. The Gli-CMC-Lip ternary composite nanoparticles in the system were used to perform an enzymatic transesterification reaction at 60℃ for 15 min to obtain an emulsion gel rich in MLCT. After the reaction was completed, the system was heated in an 85℃ water bath for 10 min to inactivate lipase and terminate the reaction. After cooling, a stable food-grade emulsion gel rich in functional lipids was obtained. 50 µL of the emulsion was dispersed in 1 mL of n-hexane using a pipette, filtered through a 0.22 µm pore size filter membrane, and analyzed by gas chromatography. The MLCT yield reached 72.38%.

[0065] Rheological and particle size analysis showed that the product maintained a stable gel three-dimensional framework (G'>G''), with an average particle size ranging from 11.96 μm to 23.46 μm.

[0066] Example 6 1. Preparation method of food-grade emulsion gel rich in functional lipids (1) Preparation of ternary composite nanoparticle dispersion Same as Example 1.

[0067] (2) Preparation of food-grade emulsion gels rich in functional lipids A mixture of flaxseed oil and coconut oil (mass ratio 5:5) was used as the oil phase, and the Gli-CMC-Lip ternary composite nanoparticle dispersion from step (1) was used as the aqueous gel matrix. The aqueous and oil phases were mixed in a volume ratio of 3:7. The emulsion gel was prepared by homogenizing at 12000 rpm for 1 min using a handheld homogenizer. The Gli-CMC-Lip ternary composite nanoparticles in the system were used to perform an enzymatic transesterification catalytic reaction at 50℃ for 15 min to obtain an emulsion gel rich in MLCT. After the reaction was completed, the system was heated in an 85℃ water bath for 10 min to inactivate lipase and terminate the reaction. After cooling, a stable food-grade emulsion gel rich in functional lipids was obtained. 50 µL of the emulsion was dispersed in 1 mL of n-hexane using a pipette, filtered through a 0.22 µm pore size filter membrane, and analyzed by gas chromatography. The MLCT yield reached 67.34%.

[0068] Characterization results show that the system can still form a continuous emulsion gel structure (G'>G'') after changing the reaction temperature, and its particle size distribution remains within the range of 11.96 μm to 23.46 μm.

[0069] Example 7 1. Preparation method of food-grade emulsion gel rich in functional lipids (1) Preparation of ternary composite nanoparticle dispersion Same as Example 1.

[0070] (2) Preparation of food-grade emulsion gels rich in functional lipids A mixture of flaxseed oil and coconut oil (mass ratio 5:5) was used as the oil phase, and the Gli-CMC-Lip ternary composite nanoparticle dispersion from step (1) was used as the aqueous gel matrix. The aqueous and oil phases were mixed in a volume ratio of 3:7. The emulsion gel was prepared by homogenizing at 12000 rpm for 1 min using a handheld homogenizer. The Gli-CMC-Lip ternary composite nanoparticles in the system were used to carry out an enzymatic transesterification reaction at 70℃ for 15 min to obtain an emulsion gel rich in MLCT. After the reaction was completed, the system was heated in an 85℃ water bath for 10 min to inactivate lipase and terminate the reaction. After cooling, a stable food-grade emulsion gel rich in functional lipids was obtained. 50 µL of the emulsion was dispersed in 1 mL of n-hexane using a pipette, filtered through a 0.22 µm pore size filter membrane, and analyzed by gas chromatography. The MLCT yield reached 71.00%.

[0071] Rheometer and particle size analyzer tests confirmed that the product under the high-temperature boundary conditions still conforms to the physical characteristics of an oil-in-water emulsion gel, with G' being significantly larger than G'' and the particle size not exceeding the protection range of 11.96 μm to 23.46 μm.

[0072] Example 8 1. Preparation method of food-grade emulsion gel (1) Preparation of ternary composite nanoparticle dispersion Same as Example 1.

[0073] (2) Preparation of food-grade emulsion gel A mixture of flaxseed oil and coconut oil (mass ratio 3:7) was used as the oil phase, and the Gli-CMC-Lip ternary composite nanoparticle dispersion in step (1) was used as the aqueous gel matrix. The aqueous phase and oil phase were mixed in a volume ratio of 3:7. The emulsion gel was prepared by homogenizing at 12000 rpm for 1 min using a handheld homogenizer. No enzymatic transesterification reaction was performed. The system was directly heated in an 85℃ water bath for 10 min to inactivate lipase. After cooling, a stable food-grade emulsion gel was obtained and directly used in baking.

[0074] Example 9 1. Preparation method of food-grade emulsion gel rich in functional lipids (1) Preparation of ternary composite nanoparticle dispersion Glycol protein was dissolved in a 70% (v / v) aqueous ethanol solution to prepare a 10.0 wt% glycol protein stock solution. Sodium carboxymethyl cellulose was dissolved in deionized water and stirred overnight at 25°C to prepare a 0.5 wt% sodium carboxymethyl cellulose stock solution.

[0075] Under stirring conditions, gliadin stock solution was slowly added dropwise to sodium carboxymethyl cellulose stock solution at a mass ratio of 2:1. The mixture was then placed in a rotary evaporator and distilled under reduced pressure at 40°C to completely remove ethanol, obtaining Gli-CMC dispersion. An aqueous solution of Pseudomonas cepacia lipase PS was added to the Gli-CMC dispersion at a volume ratio of 3:1, and the mixture was stirred continuously at 600 rpm for 2 hours in an ice-water bath to allow the lipase to adsorb onto the particle surface, resulting in Gli-CMC-Lip ternary composite nanoparticle dispersion.

[0076] The sample was characterized using the same testing methods as in Example 1. The three-phase contact angle of the Gli-CMC-Lip prepared in this example was found to be 81.4°; its Zeta potential was... 33.74 mV.

[0077] (2) Preparation of food-grade emulsion gels rich in functional lipids A mixture of flaxseed oil and coconut oil (mass ratio 3:7) was used as the oil phase, and the Gli-CMC-Lip ternary composite nanoparticle dispersion in step (1) was used as the aqueous phase gel matrix. The aqueous phase and oil phase were mixed in a volume ratio of 3:7. The emulsion gel was prepared by homogenizing at 12000 rpm for 1 min using a handheld homogenizer. The Gli-CMC-Lip ternary composite nanoparticles in the system were used to carry out an enzymatic transesterification catalytic reaction at 60℃ for 15 min to obtain an emulsion gel rich in MLCT. After the reaction was completed, the system was placed in an 85℃ water bath for 10 min to inactivate lipase, and the reaction was terminated. After cooling, a stable food-grade emulsion gel rich in functional lipids was obtained.

[0078] The emulsion was characterized using the same testing methods as in Example 1. Gas chromatography analysis showed that the MLCT yield reached 68.42%. Optical microscopy images revealed that the emulsion droplets were regularly spherical, with a droplet size of approximately 23.46 μm, and no obvious droplet aggregation or stratification was observed. Rheological tests indicated that the obtained system conformed to the characteristics of an oil-in-water emulsion gel, with its G′ significantly higher than G″, exhibiting gel behavior.

[0079] Example 10 1. Preparation method of food-grade emulsion gel rich in functional lipids (1) Preparation of ternary composite nanoparticle dispersion Glycol protein was dissolved in a 70% (v / v) aqueous ethanol solution to prepare a 10.0 wt% glycol protein stock solution. Sodium carboxymethyl cellulose was dissolved in deionized water and stirred overnight at 25°C to prepare a 0.5 wt% sodium carboxymethyl cellulose stock solution.

[0080] Under stirring conditions, gliadin stock solution was slowly added dropwise to sodium carboxymethyl cellulose stock solution at a mass ratio of 8:1. The mixture was then placed in a rotary evaporator and distilled under reduced pressure at 40°C to completely remove ethanol, obtaining Gli-CMC dispersion. An aqueous solution of Pseudomonas cepacia lipase PS was added to the Gli-CMC dispersion at a volume ratio of 3:1, and the mixture was stirred continuously at 600 rpm for 2 hours in an ice-water bath to allow the lipase to adsorb onto the particle surface, resulting in Gli-CMC-Lip ternary composite nanoparticle dispersion.

[0081] The sample was characterized using the same testing methods as in Example 1. The three-phase contact angle of the Gli-CMC-Lip prepared in this example was found to be 59.76°; its Zeta potential was... 25.99 mV.

[0082] (2) Preparation of food-grade emulsion gels rich in functional lipids A mixture of flaxseed oil and coconut oil (mass ratio 3:7) was used as the oil phase, and the Gli-CMC-Lip ternary composite nanoparticle dispersion in step (1) was used as the aqueous gel matrix. The aqueous phase and oil phase were mixed in a volume ratio of 3:7. The emulsion gel was prepared by homogenizing at 12000 rpm for 1 min using a handheld homogenizer. The Gli-CMC-Lip ternary composite nanoparticles in the system were used to carry out an enzymatic transesterification reaction at 60℃ for 15 min to obtain an emulsion gel rich in MLCT. After the reaction was completed, the system was placed in an 85℃ water bath for 10 min to inactivate lipase and terminate the reaction. After cooling, a stable food-grade emulsion gel rich in functional lipids was obtained.

[0083] The system was characterized using the same testing methods as in Example 1. Gas chromatography analysis showed that the MLCT yield reached 65.71%. Optical microscopy images showed that the emulsion droplets were well-formed spheres with a droplet size of approximately 18.29 μm. Rheological tests indicated that the obtained system conformed to the characteristics of an oil-in-water emulsion gel, with its storage modulus G′ significantly higher than its loss modulus G″, exhibiting gel behavior.

[0084] It should be noted that Examples 4-7 verified the feasibility of the present invention under different oil phase ratios and reaction temperatures, and Examples 9-10 verified the feasibility of a wider range of gel matrix ratios. All the above examples successfully achieved in-situ synthesis of MLCT and construction of the emulsion gel network framework. However, compared to the core preferred scheme (Example 1), the MLCT content of the emulsion gel prepared with the above boundary parameters was slightly lower than that of Example 1, and it was slightly insufficient in terms of interfacial film density or macroscopic gel rigidity. Therefore, it was difficult to exhibit the best structural support effect in complex dough systems simulating high-shear whipping and high-temperature baking, and was not included in subsequent baking application evaluations. This further proves that the process parameters of Example 1 (Gli to CMC mass ratio 4:1, vegetable oil to coconut oil mass ratio 3:7 in the oil phase, reaction temperature 60℃) are the optimal scheme that balances interfacial catalytic efficiency and baking processing characteristics.

[0085] Comparative Example 1 Beat 10 parts by weight of softened butter for 2 minutes. Then add 50 parts by weight of sifted low-gluten flour, 0.6 parts by weight of salt, 0.6 parts by weight of yeast, 0.3 parts by weight of baking soda, and 20 parts by weight of milk. Mix well to form a dough. Press the dough into a disc and then press it into cookie shapes using a cookie cutter. After cooling, bake in an oven at 170°C (top and bottom heat) for 15 minutes.

[0086] Whipped butter Figure 3 It is deep golden yellow, exhibiting high hardness and plasticity, but its texture is relatively rough.

[0087] The finished cookies exhibit a characteristic bright golden hue, a smooth surface, and intact edges, showcasing the hallmarks of high-quality butter cookies. Figure 4 Microscopically, it possesses large macroscopic voids and smooth, intact pore walls. Figure 5 The electronic nose detection results showed that its sample clusters were concentrated on the left negative half of the PCA plot coordinate axis, completely separated from the example group. In the raw data, the W1W response value was low (mean 3.45), while the W2S response value was high (mean 1.49), exhibiting typical traditional buttery aroma characteristics. Figure 6 ).

[0088] The texture data (Table 1) show that the product's hardness is 78583.33±381.36 g, its adhesiveness is 0.27±0.04, its elasticity is 0.56±0.05 mm, its stickiness is 20916.67±3301.07 g, and its chewiness is 11.72±1.22 mj, which will serve as a benchmark for subsequent evaluation of the fat substitution effect.

[0089] Comparative Example 2 1. Preparation method of food-grade emulsion gel rich in functional lipids Same as Example 1.

[0090] 2. Application of food-grade emulsion gels rich in functional lipids in baking Whip 10 parts by weight of the oil (all in emulsion form) for 2 minutes. Then add 50 parts by weight of sifted low-gluten flour, 0.6 parts by weight of salt, 0.6 parts by weight of yeast, 0.3 parts by weight of baking soda, and 20 parts by weight of milk. Mix well to form a dough. Press the dough into a disc and then press it into cookie shapes using a mold. After cooling, bake in an oven at 170°C (top and bottom heat) for 15 minutes.

[0091] The biscuit surface of the fully substituted group was rough, and the macroscopic structure underwent severe shrinkage. Figure 4 The pores in the cross-sectional microstructure are extremely compacted, losing the continuous spatial framework that a porous, crisp biscuit should have. Figure 5 ).

[0092] The texture test results (Table 1) show that the hardness decreased sharply to 37826.67±10417.05 g, and all texture indices dropped to their lowest levels (e.g., adhesiveness was only 4436.67±2844.19 g, and chewiness was only 1.85±1.30 mj). This indicates that after the complete removal of solid fat, the emulsion gel alone could not provide sufficient mechanical support, completely destroying the stress state and overall structural integrity of the dough during baking.

[0093] Table 1 shows the textural properties of the baked cookies obtained in Examples 1-3 and Comparative Examples 1 and 2.

[0094] Table 1

[0095] As the emulsion gel replacement ratio increased, the biscuit hardness decreased significantly, indicating a weakening of its continuous supporting framework. Related parameters decreased synchronously, further confirming that the discontinuous microstructure formed by high replacement ratios (Example 3, Comparative Example 2) weakens local mechanical strength and may not be able to maintain a stable stress state during simulated chewing. In contrast, Examples 1 and 2, while achieving lipid nutritional reconstruction, retained quality close to that of the whole butter group to the greatest extent, demonstrating the significant superiority of the moderate replacement scheme of this invention.

[0096] Figure 6The PCA results showed that the cumulative variance contribution rate of PC1 and PC2 reached 94.8%, which is sufficient to represent the overall flavor information of the sample. Combined with the loading plots, it can be seen that the significant rightward shift of the sample points in the examples is mainly driven by sensor feature vectors such as W1W (sulfur compounds) and W5C (alkanes, polar molecules). The above quantitative sensor data and spatial distribution trends strongly confirm that this invention, by constructing a ternary composite particle-stabilized emulsion gel, not only optimizes the lipid composition but also precisely controls the release behavior of volatile compounds, enabling the final product to achieve ideal flavor reconstruction.

[0097] As an extension of the application potential of this invention, if the transesterification reaction step in the aforementioned embodiments is omitted, and the emulsion gel stabilized by Gli-CMC-Lip ternary composite nanoparticles is directly mixed with butter and whipped, the inherent three-dimensional framework of the emulsion gel system can still improve the processing characteristics of the dough and the quality of the biscuits to a certain extent. The focus of protection of this invention is on the above-mentioned simultaneous preparation method involving in-situ transesterification, but the above-mentioned basic physical applications do not depart from the technical concept of this invention.

[0098] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. An enzymatic preparation method for a functional lipid-rich emulsion gel, characterized in that, Specifically, the following steps are included: (1) Preparation of ternary composite nanoparticle dispersion Glycol protein was dissolved in an aqueous ethanol solution to obtain a glycol protein stock solution, and sodium carboxymethyl cellulose was dissolved in water to obtain a sodium carboxymethyl cellulose stock solution. Under stirring conditions, the glycol protein stock solution was slowly added dropwise to the sodium carboxymethyl cellulose stock solution to remove ethanol and obtain a Gli-CMC dispersion. An aqueous solution of lipase was added to the Gli-CMC dispersion and stirred at low temperature to allow the lipase to adsorb onto the particle surface, thus obtaining a Gli-CMC-Lip ternary composite nanoparticle dispersion. (2) Preparation of food-grade emulsion gels rich in functional lipids A mixture of vegetable oil rich in long-chain fatty acids and coconut oil was used as the oil phase, and a dispersion of Gli-CMC-Lip ternary composite nanoparticles was used as the aqueous phase gel matrix to form a homogenized emulsion gel. The Gli-CMC-Lip ternary composite nanoparticles in the system were used to perform an enzymatic transesterification catalytic reaction to obtain an emulsion gel rich in MLCT. After the reaction was completed, the system was heated to inactivate lipase, the reaction was terminated, and after cooling, a stable food-grade emulsion gel rich in functional lipids was obtained.

2. The preparation method according to claim 1, characterized in that, In step (1), the ethanol-water solution contains 70% ethanol by volume; the gliadin stock solution contains 10.0 wt% gliadin; and the sodium carboxymethyl cellulose stock solution contains 0.5 wt% sodium carboxymethyl cellulose. The gliadin stock solution is slowly added dropwise to the sodium carboxymethyl cellulose stock solution, and the mass ratio of gliadin to sodium carboxymethyl cellulose is required to be 2:1 to 8:

1. The concentration of lipase in the aqueous solution is 20~100 mg / mL; The volume ratio of the aqueous lipase solution to the Gli-CMC dispersion is required to be 1:1 to 1:

5. The conditions for low-temperature stirring are an ice-water bath, a stirring speed of 600 rpm, and a time of 1 to 3 hours.

3. The preparation method according to claim 1, characterized in that, The lipase mentioned in step (1) is selected from one or more of the following: Candida columnar lipase CRL, Yersinia lipase AYS, Pseudomonas cepacia lipase PS, and Candida columnar lipase CSL.

4. The preparation method according to claim 1, characterized in that, The vegetable oil rich in long-chain fatty acids mentioned in step (2) is selected from one or more of flaxseed oil, rapeseed oil, corn oil, soybean oil, sunflower oil or peanut oil; the mass ratio of the vegetable oil rich in long-chain fatty acids to coconut oil is 1:9 to 9:1; the volume ratio of the oil phase to the aqueous phase gel matrix is ​​5:5 to 8:2; the homogenization speed is 8000 to 15000 rpm and the time is 1 to 3 min.

5. The preparation method according to claim 1, characterized in that, The temperature of the enzymatic transesterification catalytic reaction in step (2) is 40~80℃, and the time is 0~30min; The inactivation temperature of the lipase is 80~100℃, and the time is 5~15 min.

6. The preparation method according to claim 1, characterized in that, The emulsion gel mentioned in step (2) is an oil-in-water emulsion gel with an average droplet size of 11.96 μm to 23.46 μm; The emulsion gel has a supporting structure, and its rheological characteristics in the scanning frequency range of 1~100 rad / s show that the storage modulus (G') is always greater than the loss modulus (G″), with the G' value between 100 and 200 Pa.

7. The application of a food-grade emulsion gel rich in functional lipids prepared by the method according to any one of claims 1 to 6 in baking, characterized in that, The specific steps are as follows: The food-grade emulsion gel rich in functional lipids is mixed with butter in any proportion and whipped to obtain a fat mixture; the fat mixture is then mixed with other ingredients to form a dough, which is then shaped and baked to obtain the final product.

8. The application according to claim 7, characterized in that, The whipping time is 1.5~2 min; the specific mass ratio of the oil mixture to other ingredients is 8~12 parts oil mixture, 45~55 parts low-gluten flour, 0.4~0.8 parts salt, 0.4~0.8 parts yeast, 0.2~0.4 parts baking soda, and 15~20 parts milk; the baking temperature is 160~200℃.

9. The application according to claim 7 or 8, characterized in that, The volatile flavor characteristics of the final product meet the following parameters: Detected by a PEN3 electronic nose containing a metal oxide semiconductor sensor, the response value of the sensor W1W, which is sensitive to sulfur compounds, is 5.30~5.53, and the response value of the sensor W2S, which is sensitive to alcohols and some aromatic compounds, is 1.26~1.32; further principal component analysis shows that the final product has the natural coconut aroma volatile flavor characteristics formed by the directional release of coconut oil components from the emulsion gel, with a flavor retention rate greater than 90%.

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