Camellia oleifera seed oil emulsion gel based on polyphenol-gelatin synergistic stabilization and construction method and application thereof

Abstract

The application discloses a method for constructing oil-tea camellia seed oil-based emulsion gel loaded with grape seed polyphenols and application of the emulsion gel in cookies. The method uses self-extracted grape seed polyphenols and self-extracted gelatin as a gel matrix, and oil-tea camellia seed oil as an oil phase to construct an emulsion gel with a compact three-dimensional network structure through intermolecular interactions such as hydrogen bonds. The optimized process is that the oil-water ratio is 7:3, the gelatin is 3%, the polyphenol is 0.1%, and the monoglyceride is 6%. The oil retention rate of the obtained gel reaches 86.91%, and the polyphenol embedding rate reaches 98.71%, which is significantly better than that of a commercial raw material combination (Example 1). The emulsion gel can be used as a butter substitute in cookies, and the substitution rate reaches 75%. The emulsion gel significantly reduces the content of saturated fatty acids in the product (the reduction is about 15%), improves the fatty acid composition, delays starch digestion (the proportion of resistant starch is increased from 20.92% to 28.28%), prolongs the shelf life (the shelf life of the 0.1% polyphenol group is 390 days, which is 1.6 times that of the blank group and 1.16 times that of the Example 1), and maintains good sensory quality and processing performance. The application provides a new fat replacement strategy for the development of healthy baked foods.

Description

Technical Field

[0001] This invention belongs to the field of food processing and functional food technology, specifically relating to a camellia seed oil emulsion gel based on the synergistic stabilization of grape seed polyphenols and gelatin, its construction method, and the application of the emulsion gel as a butter substitute in cookies. Background Technology

[0002] Cookies, a classic Western-style pastry made primarily from flour, fat, and sugar through baking, are beloved by consumers. Traditional cookies often use butter as their main fat source. Butter's unique solid fat properties, suitable plasticity range, and good emulsifying properties allow the dough to incorporate sufficient air during mixing, forming a stable emulsion structure. This gives the dough suitable plasticity and resistance to extensibility, facilitating molding and resulting in a loose, porous structure and crisp texture after baking. However, butter is expensive and high in saturated fatty acids. Long-term excessive intake is closely related to health risks such as obesity and cardiovascular disease, prompting researchers and manufacturers to actively explore alternative fats.

[0003] Liquid vegetable oils (such as soybean oil, corn oil, and camellia seed oil) are rich in unsaturated fatty acids, making them an ideal source of healthy fats. However, due to the lack of a β'-type crystallization network, liquid vegetable oils struggle to effectively incorporate air and form a stable emulsion during the mixing stage. This results in dough that is excessively sticky and elongated, leading to cookies that spread out too much and lack thickness after baking, resulting in a heavy and unpleasant texture. Therefore, structuring liquid vegetable oils to give them similar plasticity and processing properties to butter is a key technological challenge for achieving a healthy alternative.

[0004] Emulsion gels are a class of structured materials formed by stably embedding or encapsulating emulsion droplets within a three-dimensional gel network through physical or chemical processes, possessing the dual properties of both emulsions and gels. This unique structure endows emulsion gels with tunable rheological properties (such as hardness, elasticity, and spreadability), excellent physical stability (anti-agglomeration, anti-Oswald ripening), and efficient encapsulation and controlled release capabilities for functional ingredients. In recent years, emulsion gels have received widespread attention in the field of fat substitution, as they can encapsulate liquid vegetable oils within a stable three-dimensional gel network, thereby mimicking the physical and rheological properties of traditional solid fats.

[0005] Camellia seed oil is rich in monounsaturated fatty acids (oleic acid content exceeds 80%) and contains abundant squalene, vitamin E, and other natural antioxidants, exhibiting excellent thermal oxidative stability. However, camellia seed oil is liquid at room temperature, and directly replacing butter can lead to deterioration in dough processing performance. Gelatin, as a natural polymeric gelling agent, possesses good gelling, film-forming, and biocompatibility, but the thermal stability and oil-holding capacity of a single gelatin gel network need further improvement. Grape seed polyphenols (GSP) are natural antioxidants extracted from grape seeds, a byproduct of the winemaking industry. They are mainly composed of proanthocyanidins (approximately 60%–70%), catechins, epicatechins, and other flavonoids, with an antioxidant capacity 50 times that of vitamin E and 20 times that of vitamin C. However, GSP has poor water solubility and chemical stability, and is easily oxidized and degraded during food processing and storage, limiting its direct application.

[0006] Existing studies have utilized protein- or polysaccharide-stabilized emulsion gels to replace some of the butter in baked goods, but these studies have the following shortcomings: (1) Most existing technologies focus on the construction of the gel system itself, without fully utilizing the synergistic effect of endogenous antioxidant components and polyphenols in the oil phase matrix (such as camellia seed oil); (2) The regulatory mechanism of emulsion gels on the glass transition temperature and moisture distribution of dough has not been systematically investigated; (3) The starch digestibility of cookie products after replacing butter with emulsion gels has not been evaluated. Therefore, developing a method to construct an emulsion gel using gelatin-grape seed polyphenols to synergistically stabilize camellia seed oil, and systematically solve the problems of liquid vegetable oil structuring, efficient polyphenol encapsulation and controlled release, and the balance between cookie nutritional quality and processing performance, has significant innovative value and application prospects. Summary of the Invention

[0007] The purpose of this invention is to overcome the shortcomings of the prior art and provide a camellia seed oil-based emulsion gel loaded with grape seed polyphenols, its construction method, and its application in cookies. By synergistic stabilizing effect of grape seed polyphenols and gelatin, liquid camellia seed oil is structured to construct an emulsion gel with near-solid plasticity and excellent thermal stability, thereby achieving the substitution of butter and nutritional fortification, sensory optimization, improved digestibility, and extended shelf life of cookie products.

[0008] The technical problem solved by this invention is achieved through the following technical solution: This invention provides a method for constructing a camellia seed oil-based emulsion gel loaded with grape seed polyphenols, comprising the following steps: (1) Dissolve gelatin and grape seed polyphenols in water and stir until homogeneous to obtain an aqueous phase; (2) Dissolve monoglycerides in camellia seed oil, heat and stir until completely dissolved, and cool to form an oil gel as the oil phase; (3) Mix the aqueous phase and the oil phase at an oil-water mass ratio of 5:5 to 9:1 and emulsify to obtain an emulsion gel; The gelatin content is 1%–4% of the water phase mass, the grape seed polyphenol content is 0.05%–0.3% of the water phase mass, and the monoglyceride content is 4%–8% of the oil phase mass. The extraction method of grape seed polyphenols includes: crushing grape seeds, extracting them with a 50%–80% (v / v) ethanol aqueous solution at 50–70°C for 1–3 hours, combining the extracts, concentrating and drying them, and purifying them with macroporous adsorption resin. The obtained grape seed polyphenols contain ≥60% proanthocyanidins. The method for preparing the gelatin includes: using animal skin or bone as raw material, pre-treating it by alkaline or acidic method, extracting it by boiling, concentrating and drying it, and obtaining gelatin with a gel strength of 150-300g.

[0009] Preferably, the oil-water mass ratio is 6.8-7.2:3, the amount of gelatin added is 2.8%-3.2% of the mass of the aqueous phase, the amount of grape seed polyphenols added is 0.08-0.12% of the mass of the aqueous phase, and the amount of monoglyceride added is 5.8%-6.2% of the mass of the oil phase.

[0010] More preferably, the oil-to-water mass ratio is 7:3, the amount of gelatin added is 3% of the mass of the aqueous phase, the amount of grape seed polyphenols added is 0.1% of the mass of the aqueous phase, and the amount of monoglyceride added is 6% of the mass of the oil phase.

[0011] A further preferred method for extracting grape seed polyphenols includes: (1) Dry the grape seeds until the moisture content is ≤10%, then crush them through a 40-60 mesh sieve to obtain grape seed powder; (2) Add grape seed powder to an ethanol aqueous solution with a volume fraction of 50% to 80%, with a material-to-liquid ratio of 1:8 to 1:20 g / mL, and stir and extract in a water bath at 50 to 70°C for 1 to 3 hours. Repeat the extraction 1 to 3 times and combine the extracts. (3) The extract was concentrated under reduced pressure at 50-60℃ to 1 / 5-1 / 10 of its original volume, and then freeze-dried or spray-dried to obtain crude grape seed polyphenol extract; (4) The crude extract was purified by macroporous adsorption resin column chromatography, eluted with ethanol-water gradient, and the fraction rich in proanthocyanidins was collected. After concentration and drying, refined grape seed polyphenols were obtained, in which the proanthocyanidin content was ≥60%.

[0012] A further preferred method for preparing self-extracted gelatin includes: (1) Using animal skin or animal bones as raw materials, after washing and chopping, soak in 3% to 5% lime water for 15 to 30 days, changing the solution 2 to 3 times during the period, and carry out alkaline pretreatment; or use acid pretreatment, soaking in 0.5% to 1% hydrochloric acid for 12 to 24 hours. (2) Rinse the pretreated raw material with water until neutral, add 2 to 4 times the volume of deionized water, extract at 60 to 80°C for 4 to 8 hours, filter and collect the filtrate; (3) The filtrate is concentrated under reduced pressure at 50-60°C to a solid content of 20%-30%, and then freeze-dried or spray-dried to obtain gelatin powder.

[0013] Further, the crude extract was purified by macroporous adsorption resin column chromatography with gradient elution of ethanol and aqueous solution. The specific elution process was as follows: first, the column was washed with 2 to 3 column volumes of distilled water to remove polar impurities and water-soluble sugars; then, elution was performed with 30% to 50% ethanol and aqueous solution, and the eluent was discarded; the 60% to 80% ethanol and aqueous solution eluent was collected, concentrated and dried to obtain purified grape seed polyphenols with a proanthocyanidin content of ≥60%.

[0014] This invention provides a camellia seed oil-based emulsion gel, constructed according to the above method.

[0015] This invention provides the application of camellia seed oil-based emulsion gel as a butter substitute in baked goods.

[0016] Preferably, the baked goods are cookies, and the proportion of the emulsion gel replacing butter is 50% to 100%, preferably 75%.

[0017] This invention provides a cookie made from the following ingredients in parts by weight: 100 parts low-gluten flour, 8-15 parts of the above-mentioned emulsion gel, 0-5 parts butter, 30-40 parts corn oil, 5-15 parts enzymatically hydrolyzed butter, 1-5 parts sesame oil, 20-30 parts granulated sugar, 5-10 parts whole egg liquid, and 1-3 parts baking soda; the cookie is prepared by mixing, shaping, and baking; preferably, the baking conditions are: 160-180°C for the top heat and 140-160°C for the bottom heat, for 8-15 minutes; more preferably, the baking conditions are: 170°C for the top heat and 150°C for the bottom heat, for 10 minutes.

[0018] The cookie is used in the preparation of functional foods that are low in saturated fat, rich in polyphenols, and have improved starch digestibility and extended shelf life.

[0019] The present invention will be further explained and described below: To further explain, this section is the core of the invention: a camellia seed oil-based emulsion gel is constructed through the synergistic stabilizing effect of grape seed polyphenols and gelatin. The detailed steps for preparing the emulsion gel are as follows: (1) Aqueous phase preparation Gelatin and grape seed polyphenols (GSP) were dissolved in purified water. The amount of gelatin added was 1% to 4% (preferably 3%) of the aqueous phase mass, and the amount of grape seed polyphenols added was 0.05% to 0.3% (preferably 0.1%) of the aqueous phase mass. The solution was stirred at 600 to 1000 rpm for 10 to 30 minutes at room temperature (20 to 30°C) until completely dissolved, thus obtaining an aqueous solution.

[0020] (2) Preparation of oil phase Monoglycerides (4%–8% by mass of the oil phase, preferably 6%) are added to camellia seed oil. The mixture is heated in a water bath at 70–90°C and stirred at 800–1200 rpm for 15–25 minutes until the monoglycerides are completely dissolved, yielding an oil phase solution. The oil phase solution is then left at room temperature for 12–24 hours to form an oil gel.

[0021] (3) Emulsification and gelation The aqueous and oil phases are mixed at an oil-water mass ratio of 5:5 to 9:1 (preferably 7:3), and emulsified by stirring at 1000 to 2000 rpm for 20 to 40 minutes to form a homogeneous emulsion gel. The resulting emulsion gel is allowed to stand at room temperature for 2 to 4 hours to allow its network structure to fully stabilize.

[0022] Through extensive experimental screening and creative work, the key process parameters were selected as follows: Oil-water mass ratio: The preferred oil-water mass ratio is 7:3. At this ratio, the camellia seed oil-based emulsion gel forms a uniform and dense three-dimensional network structure with the smallest droplet size and the highest oil retention rate.

[0023] Gelatin concentration: preferably 3% of the aqueous phase mass, at which the gel strength and oil retention are both optimal.

[0024] GSP concentration: preferably 0.1% of the aqueous phase mass, at which point the oil retention rate reaches 86.91%, the polyphenol encapsulation rate is as high as 98.71%, and the antioxidant activity and thermal stability are optimal.

[0025] Mechanism explanation: Grape seed polyphenols are rich in phenolic hydroxyl groups, while gelatin molecules contain amino and carboxyl groups. The two form a complex cross-linked network through non-covalent bonds such as hydrogen bonds and hydrophobic interactions, significantly enhancing the three-dimensional structural strength and thermal stability of the gel. Fourier transform infrared spectroscopy analysis confirmed that the interaction between GSP and gelatin is mainly through hydrogen bonds, rather than the formation or breaking of chemical bonds (Wang et al. 2022; Luo et al. 2024). The high content of monounsaturated fatty acids (oleic acid) and natural antioxidants (squalene, vitamin E) in camellia seed oil is conducive to the formation of a stable interfacial layer, which, in synergy with the gelatin-GSP complex network, achieves efficient encapsulation of oils and protection of polyphenols. Thermodynamic analysis showed that the crystallization peak temperature of the GSP-loaded emulsion gel reached 46.8–47.4℃, and the melting peak temperature reached 105.5–130.3℃, far exceeding the crystallization temperature (20.0℃) and melting temperature (39.4℃) of butter, demonstrating the excellent thermal stability of this system.

[0026] The emulsion gel described in this invention can be used as a solid fat substitute in baked goods such as cookies, replacing part or all of the butter. Specific application methods are as follows: (1) Preparation of cookie dough Prepare cookie dough according to the following recipe (by weight): 100 portions of low-gluten flour The present invention comprises 8-15 parts of emulsion gel (preferably 10.5 parts, corresponding to a butter substitution rate of 75%). 0-5 parts butter (preferably 3.5 parts) 30-40 parts corn oil (40 parts preferred) 5-15 parts enzymatically hydrolyzed butter (preferably 10 parts) Sesame oil 1-5 parts (preferably 3 parts) 20-30 parts granulated sugar (30 parts preferred) 5-10 parts whole egg liquid (preferably 8 parts) 1 to 3 parts baking soda (preferably 2 parts) Water 0-5 parts (preferably 0 parts) Mix corn oil, emulsion gel, butter, sesame oil, and granulated sugar until smooth; add whole egg liquid and continue beating; then add baking soda and low-gluten flour and mix well to form a dough. The emulsion gel replaces 50% to 100% of the butter, preferably 75%.

[0027] (2) Cookie shaping and baking Divide the dough into small portions of 10-20g (preferably 15g) each, and extrude them into cookie shapes. Preheat the oven to 160-180℃ (top heat) and 140-160℃ (bottom heat) (preferably 170℃ (top heat) and 150℃ (bottom heat)) and bake for 8-15 minutes (preferably 10 minutes). Remove and cool to obtain the functional cookie product.

[0028] (3) Application effect The cookies prepared using the emulsion gel of this invention as a substitute for butter have the following significant advantages: Nutritional health: The content of saturated fatty acids was significantly reduced, from 28.615% in the control group to 24.355%, a decrease of about 15%; monounsaturated fatty acids increased from 31.096% to 33.383%, and polyunsaturated fatty acids increased from 40.288% to 42.261%, indicating a significant optimization of fatty acid composition.

[0029] Sensory quality: Cookies with 0.1% GSP added showed the best performance in color (L* value 21.13), texture, crispness and overall acceptability; volatile flavor analysis showed that an appropriate amount of GSP inhibited the off-flavor of excessive lipid oxidation, while retaining and enriching the characteristic aroma components such as pyrazines and lactones produced by the Maillard reaction, making the flavor layers more harmonious and full.

[0030] Texture properties: The emulsion gel improved the dough texture, reducing the dough hardness from 2462.44N to 626.95N, increasing the elasticity from 0.12mm to 0.19mm, and increasing the cohesiveness from 0.08mJ to 0.16mJ; the cookie products achieved an optimized balance between crispness and chewiness while maintaining good hardness and elasticity.

[0031] Digestive properties: GSP effectively regulates starch digestion behavior, reducing the content of rapidly digestible starch (RDS) from 57.53% to 52.44% and increasing the proportion of resistant starch (RS) from 20.92% to 28.28%, which helps to reduce the product's estimated glycemic index.

[0032] Oxidative stability: The strong antioxidant activity of GSP significantly extends the shelf life of products. The shelf life of the 0.1% GSP group is 390 days, which is 1.6 times that of the blank group; the shelf life of the 0.3% GSP group is 468 days, which is 1.92 times that of the blank group.

[0033] The present invention can also be applied to other baked goods (such as bread, cakes, pie crusts), spreads, ice cream, chocolate and other foods that require solid fats. Detailed Implementation

[0034] Example 1 This embodiment uses self-extracted grape seed polyphenols and self-extracted gelatin to prepare emulsion gels and cookies.

[0035] The grape seed polyphenols used in this invention are extracted from grape seeds, a byproduct of the winemaking industry. The specific steps for self-extraction of grape seed polyphenols are as follows: (1) Raw material pretreatment: Dry the grape seeds to a moisture content of ≤10%, crush them through a 40-60 mesh sieve to obtain grape seed powder.

[0036] (2) Solvent extraction: Grape seed powder was added to a 70% ethanol aqueous solution at a material-to-liquid ratio of 1:10 (g / mL), and the mixture was stirred and extracted in a 60℃ water bath for 2 hours. The extraction was repeated twice, and the extracts were combined.

[0037] (3) Concentration and drying: The extract is concentrated to 1 / 7 of its original volume under reduced pressure at 60°C, and then freeze-dried or spray-dried to obtain crude grape seed polyphenol extract.

[0038] (4) Purification: The crude extract was purified by column chromatography using macroporous adsorption resin (such as AB-8, D101), with gradient elution using ethanol-water solution. The fraction rich in proanthocyanidins was collected, concentrated, and dried to obtain purified grape seed polyphenols with a proanthocyanidin content ≥60%. The specific elution process was as follows: first, the column was rinsed with 3 column volumes of distilled water to remove polar impurities and water-soluble sugars; then, elution was performed with 50% ethanol-water solution, and the eluent was discarded; the 80% ethanol-water solution eluent was collected, concentrated, and dried to obtain purified grape seed polyphenols with a proanthocyanidin content ≥60%.

[0039] The specific steps for using self-gelatin are as follows: (1) Raw material processing: Animal skin (pig skin, cow skin) or animal bones are used as raw materials. After cleaning and chopping, they are soaked in 5% lime water for 20 days, with the solution changed twice during the period, and alkaline pretreatment is carried out; or acid pretreatment is used (soaking in 0.8% hydrochloric acid for 20 hours).

[0040] (2) Water extraction: Rinse the pretreated raw material with water until neutral, add 3 times the volume of deionized water, extract at 70°C for 6 hours, and filter to collect the filtrate.

[0041] (3) Concentration and drying: The filtrate is concentrated under reduced pressure at 50°C to a solid content of 25%, and then freeze-dried or spray-dried to obtain gelatin powder.

[0042] A method for constructing a camellia seed oil-based emulsion gel loaded with grape seed polyphenols, the specific steps of which are as follows: Weigh 3g of self-extracted gelatin and 0.1g of self-extracted grape seed polyphenols and dissolve them in 96.9g of purified water. Stir at 800rpm for 15 minutes at room temperature (25℃) until completely dissolved to obtain an aqueous solution.

[0043] Weigh 6g of monoglyceride and 94g of camellia seed oil, and stir at 1000rpm for 20 minutes under 80℃ water bath heating conditions until the monoglyceride is completely dissolved to obtain an oil phase solution. Let the oil phase solution stand at room temperature for 24 hours to form an oil gel.

[0044] The aqueous phase and oil phase were mixed at a mass ratio of 7:3 (i.e., 70g of oil phase and 30g of aqueous phase), and emulsified by stirring at 1500rpm for 30 minutes to form a homogeneous emulsion gel. The resulting emulsion gel was allowed to stand at room temperature for 2 hours.

[0045] A type of cookie is made from the following ingredients by weight: 100g low-gluten flour, 40g corn oil, 10g enzymatically hydrolyzed butter, 10.5g of the above emulsion gel, 3.5g butter, 3g sesame oil, 30g granulated sugar, 8g whole egg liquid, and 2g baking soda.

[0046] Preparation method: Mix corn oil, emulsion gel, butter, sesame oil, and granulated sugar until smooth; add whole egg liquid and continue beating; then add baking soda and low-gluten flour and mix well to form a dough. Divide the dough into small balls and shape them. Preheat the oven to 170℃ (top heat) and 150℃ (bottom heat) for 10 minutes, bake for 10 minutes, remove and cool to obtain the cookie product.

[0047] Example 2 This embodiment uses grape seed polyphenols from Example 1 and commercially available food-grade gelatin to prepare emulsion gels and cookies.

[0048] In the preparation of the emulsion gel, 3g of commercially available gelatin (brand: Rousselot, model: 250 Bloom, gel strength 250g) and 0.1g of self-extracted grape seed polyphenols were weighed and dissolved in 96.9g of purified water. The remaining steps were the same as in Example 1.

[0049] The specific preparation steps for the cookies are the same as in Example 1.

[0050] Example 3 This embodiment uses commercially available food-grade grape seed polyphenols (purity ≥95%) and gelatin extracted by the method of Example 1 to prepare emulsion gels and cookies.

[0051] In the preparation of the emulsion gel, 3g of self-extracted gelatin and 0.1g of commercially available grape seed polyphenols (purchased from Tianjin Jianfeng Natural Products Research and Development Co., Ltd., with a proanthocyanidin content ≥95%) were weighed and dissolved in 96.9g of purified water. The remaining steps were the same as in Example 1.

[0052] The specific preparation steps for the cookies are the same as in Example 1.

[0053] Compare with Example 1 This comparative example uses commercially available food-grade grape seed polyphenols (purchased from Tianjin Jianfeng Natural Products Research and Development Co., Ltd., with proanthocyanidin content ≥95%) and commercially available food-grade gelatin (brand: Rousselot, model: 200 Bloom, gel strength 200g) to prepare emulsion gels and cookies.

[0054] In the preparation of the emulsion gel, 3g of commercially available gelatin and 0.1g of commercially available grape seed polyphenols were weighed and dissolved in 96.9g of purified water. The remaining steps were the same as in Example 1.

[0055] The specific preparation steps for the cookies are the same as in Example 1.

[0056] Compare with Example 2 The cookie preparation steps are the same as in Example 1, except that no emulsion gel is added and the amount of butter is increased to 14g (i.e., 100% butter), while the rest of the recipe is the same.

[0057] Compare with Example 3 The cookie preparation steps are the same as in Example 1, except that grape seed polyphenols (i.e., gelatin-camellia seed oil emulsion gel, without GSP) are not added to the emulsion gel, while the rest of the formula is the same.

[0058] Performance test results (1) Comparison of emulsion and gel properties Table 1. Effects of different raw material source combinations on the gel properties of camellia seed oil-based emulsions.

[0059] Note: Different lowercase letters in the same row indicate significant differences. P<0.05 In this context, the earlier the letter appears (e.g., 'a'), the larger the value; the later the letter appears (e.g., 'c'), the smaller the value.

[0060] As shown in Table 1, Example 1 significantly outperformed other combinations in terms of oil retention, GSP encapsulation rate, gel strength, antioxidant activity, and thermal stability. Self-extracted grape seed polyphenols, due to their higher proanthocyanidin content (≥60%) and greater density of active phenolic hydroxyl groups, can form a denser hydrogen bond network with gelatin; the self-extracted gelatin also has a more uniform molecular weight distribution, resulting in a more ordered gel network. The synergistic effect of these two factors leads to optimal overall performance of the emulsion gel. In contrast, Comparative Example 1 exhibited the lowest performance across all categories, clearly demonstrating the decisive influence of raw material source on the quality of the emulsion gel.

[0061] (2) Texture characteristics of cookie dough Table 2. Effects of different combinations of raw material sources on dough texture

[0062] Note: Different lowercase letters in the same row indicate significant differences. P<0.05In this context, the earlier the letter appears (e.g., 'a'), the larger the value; the later the letter appears (e.g., 'c'), the smaller the value.

[0063] As shown in Table 2, Example 1 showed the most significant improvement in dough texture: the dough hardness decreased the most, from 2462.44 N to 626.95 N, and the elasticity and cohesiveness increased the most. This is attributed to the more uniform and dense three-dimensional network structure of the emulsion gel constructed from self-extracted raw materials, which can more effectively optimize the moisture distribution and network structure of the dough.

[0064] (3) Fatty acid composition of cookies Table 3. Effects of different raw material source combinations on the fatty acid composition of cookies

[0065] Note: Different lowercase letters in the same row indicate significant differences. P<0.05 In this context, the earlier the letter appears (e.g., 'a'), the larger the value; the later the letter appears (e.g., 'c'), the smaller the value.

[0066] As shown in Table 3, Example 1 showed the most significant optimization effect on fatty acid composition: the content of saturated fatty acids was reduced to the lowest level, while the proportion of monounsaturated and polyunsaturated fatty acids increased the most. This is due to the stronger antioxidant activity of the self-extracted GSP, which more effectively protects unsaturated fatty acids from oxidative degradation during processing.

[0067] (4) Digestive characteristics of cookie starch Table 4. Effects of different raw material source combinations on the digestibility of cookie starch

[0068] Note: Different lowercase letters in the same row indicate significant differences. P<0.05 In this context, the earlier the letter appears (e.g., 'a'), the larger the value; the later the letter appears (e.g., 'c'), the smaller the value.

[0069] Table 4 shows that Example 1 exhibits the best regulatory effect on starch digestion behavior: it has the lowest content of rapidly digestible starch and the highest proportion of resistant starch. The higher content of proanthocyanidins in the self-extracted GSP can more effectively bind to starch molecules through hydrogen bonds and hydrophobic interactions, forming a V-shaped complex that is difficult to be enzymatically hydrolyzed.

[0070] (5) Shelf life prediction Table 5. Shelf life prediction for cookies with different ingredient sources

[0071] As shown in Table 5, Example 1 had the longest shelf life, which was 1.60 times that of the whole butter control group and 1.16 times that of Control Example 1. The higher content of phenolic hydroxyl groups in the self-extracted GSP provided stronger free radical neutralization ability, and the more uniform network structure of the self-extracted gelatin provided a better protective environment for the GSP. The synergistic effect of the two significantly enhanced the oxidative stability of the cookies.

[0072] Example 4 Homemade grape seed polyphenol extraction The grape seed polyphenols used in this invention are extracted from grape seeds, a byproduct of the winemaking industry. The specific steps for self-extraction of grape seed polyphenols are as follows: (1) Raw material pretreatment: The grape seeds are dried to a moisture content of ≤10%, crushed and passed through a 60-mesh sieve to obtain grape seed powder.

[0073] (2) Solvent extraction: Add grape seed powder to a 50% ethanol aqueous solution at a material-to-liquid ratio of 1:20 (g / mL), and extract by stirring in a 50℃ water bath for 3 hours. Repeat the extraction 3 times and combine the extracts.

[0074] (3) Concentration and drying: The extract is concentrated to 1 / 10 of its original volume under reduced pressure at 50°C, and then freeze-dried or spray-dried to obtain crude grape seed polyphenol extract.

[0075] (4) Purification: The crude extract was purified by column chromatography using macroporous adsorption resin (preferably AB-8 or D101 type). The specific elution process was as follows: first, the extract was washed with 2 column volumes of distilled water to remove polar impurities and water-soluble sugars; then, it was eluted with a 40% (v / v) ethanol aqueous solution, and the eluent was discarded; the 70% (v / v) ethanol aqueous solution eluent was collected, concentrated and dried to obtain purified grape seed polyphenols, of which the proanthocyanidin content was ≥60%.

[0076] The specific steps for using self-gelatin are as follows: (1) Raw material processing: Animal skin (pig skin, cow skin) or animal bones are used as raw materials. After cleaning and chopping, they are soaked in 3% lime water for 30 days, with the solution changed 3 times during the period, and alkaline pretreatment is carried out; or acid pretreatment is used (soaking in 1% hydrochloric acid for 12 hours).

[0077] (2) Water extraction: Rinse the pretreated raw material with water until neutral, add 2 times the volume of deionized water, extract at 80℃ for 4 hours, filter and collect the filtrate.

[0078] (3) Concentration and drying: The filtrate is concentrated under reduced pressure at 60°C to a solid content of 28%, and then freeze-dried or spray-dried to obtain gelatin powder.

[0079] A method for constructing a camellia seed oil-based emulsion gel loaded with grape seed polyphenols, the specific steps of which are as follows: Weigh 3.2g of self-extracted gelatin and 0.1g of self-extracted grape seed polyphenols and dissolve them in 96.7g of purified water. Stir at 700rpm for 20 minutes at room temperature (25℃) until completely dissolved to obtain an aqueous solution.

[0080] Weigh 6.2g of monoglyceride and 93.8g of camellia seed oil, and stir at 1200rpm for 15 minutes under a water bath heating condition at 90℃ until the monoglyceride is completely dissolved to obtain an oil phase solution. Let the oil phase solution stand at room temperature for 12 hours to form an oil gel.

[0081] The aqueous phase and oil phase were mixed at a mass ratio of 7:3 (i.e., 70g of oil phase and 30g of aqueous phase), and emulsified by stirring at 2000 rpm for 25 minutes to form a homogeneous emulsion gel. The resulting emulsion gel was allowed to stand at room temperature for 3 hours.

[0082] A type of cookie is made from the following ingredients by weight: 100g low-gluten flour, 40g corn oil, 15g enzymatically hydrolyzed butter, 15g of the above emulsion gel, 3g butter, 4g sesame oil, 25g granulated sugar, 10g whole egg liquid, and 2g baking soda.

[0083] Preparation method: Mix corn oil, emulsion gel, butter, sesame oil, and granulated sugar until smooth; add whole egg liquid and continue beating; then add baking soda and low-gluten flour and mix well to form a dough. Divide the dough into small balls and shape them. Preheat the oven to 160℃ (top and bottom heat) for 15 minutes, bake for 10 minutes, remove and cool to obtain the cookie product.

[0084] The cookie product of Example 4 is comparable to that of Example 1 in terms of texture and taste, and still maintains the advantages of low spreadability, low saturated fat and high resistant starch, which proves that the present invention has good applicability in different formulations within the scope of the present invention.

Claims

1. A method for constructing a camellia seed oil-based emulsion gel loaded with grape seed polyphenols, characterized in that, Includes the following steps: (1) Dissolve gelatin and grape seed polyphenols in water and stir until homogeneous to obtain an aqueous phase; (2) Dissolve monoglycerides in camellia seed oil, heat and stir until completely dissolved, and cool to form an oil gel as the oil phase; (3) Mix the aqueous phase and the oil phase at an oil-water mass ratio of 5:5 to 9:1 and emulsify to obtain an emulsion gel; The gelatin content is 1%–4% of the water phase mass, the grape seed polyphenol content is 0.05%–0.3% of the water phase mass, and the monoglyceride content is 4%–8% of the oil phase mass. The extraction method of grape seed polyphenols includes: crushing grape seeds, extracting them with a 50%–80% (v / v) ethanol aqueous solution at 50–70°C for 1–3 hours, combining the extracts, concentrating and drying them, and purifying them with macroporous adsorption resin. The obtained grape seed polyphenols contain ≥60% proanthocyanidins. The method for preparing the gelatin includes: using animal skin or bone as raw material, pre-treating it by alkaline or acidic method, extracting it by boiling, concentrating and drying it, and obtaining gelatin with a gel strength of 150-300g.

2. The method according to claim 1, characterized in that, The oil-water mass ratio is 6.8-7.2:3, the amount of gelatin added is 2.8%-3.2% of the mass of the aqueous phase, the amount of grape seed polyphenols added is 0.08-0.12% of the mass of the aqueous phase, and the amount of monoglyceride added is 5.8%-6.2% of the mass of the oil phase.

3. The method according to claim 2, characterized in that, The oil-to-water mass ratio is 7:3, the amount of gelatin added is 3% of the mass of the aqueous phase, the amount of grape seed polyphenols added is 0.1% of the mass of the aqueous phase, and the amount of monoglyceride added is 6% of the mass of the oil phase.

4. The method according to claim 1, characterized in that, The method for extracting self-extracted grape seed polyphenols includes: (1) Dry the grape seeds until the moisture content is ≤10%, then crush them through a 40-60 mesh sieve to obtain grape seed powder; (2) Add grape seed powder to an ethanol aqueous solution with a volume fraction of 50% to 80%, with a material-to-liquid ratio of 1:8 to 1:20 g / mL, and stir and extract in a water bath at 50 to 70°C for 1 to 3 hours. Repeat the extraction 1 to 3 times and combine the extracts. (3) The extract was concentrated under reduced pressure at 50-60℃ to 1 / 5-1 / 10 of its original volume, and then freeze-dried or spray-dried to obtain crude grape seed polyphenol extract; (4) The crude extract was purified by macroporous adsorption resin column chromatography, eluted with ethanol-water gradient, and the fraction rich in proanthocyanidins was collected. After concentration and drying, refined grape seed polyphenols were obtained, in which the proanthocyanidin content was ≥60%.

5. The method according to claim 1, characterized in that, The method for preparing the self-extracted gelatin includes: (1) Using animal skin or animal bones as raw materials, after washing and chopping, soak in 3% to 5% lime water for 15 to 30 days, changing the solution 2 to 3 times during the period, and carry out alkaline pretreatment; or use acid pretreatment, soaking in 0.5% to 1% hydrochloric acid for 12 to 24 hours. (2) Rinse the pretreated raw material with water until neutral, add 2 to 4 times the volume of deionized water, extract at 60 to 80°C for 4 to 8 hours, filter and collect the filtrate; (3) The filtrate is concentrated under reduced pressure at 50-60°C to a solid content of 20%-30%, and then freeze-dried or spray-dried to obtain gelatin powder.

6. A camellia seed oil-based emulsion gel, characterized in that, Constructed according to any one of claims 1 to 5.

7. The application of the camellia seed oil-based emulsion gel according to claim 6 as a butter substitute in baked goods.

8. The application according to claim 7, characterized in that, The baked goods are cookies, and the proportion of the emulsion gel replacing butter is 50% to 100%, preferably 75%.

9. A type of cookie, characterized in that, Made from the following ingredients in parts by weight: 100 parts low-gluten flour, 8-15 parts emulsion gel as described in claim 6, 0-5 parts butter, 30-40 parts corn oil, 5-15 parts enzymatically hydrolyzed butter, 1-5 parts sesame oil, 20-30 parts granulated sugar, 5-10 parts whole egg liquid, and 1-3 parts baking soda; obtained by stirring, mixing, shaping, and baking; preferably, the baking conditions are: 160-180°C for the top heat and 140-160°C for the bottom heat, for 8-15 minutes; more preferably, the baking conditions are: 170°C for the top heat and 150°C for the bottom heat, for 10 minutes.

10. The use of the cookies of claim 8 or 9 in the preparation of functional foods that are low in saturated fat, rich in polyphenols, and have improved starch digestibility and extended shelf life.

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