Pickering emulsion with oral pH and enzyme dual response and its preparation and application in oil salt reduction control

Abstract

This invention belongs to the field of oil and salt reduction technology in food processing, and discloses a Pickering emulsion with dual oral pH and enzyme responses, its preparation, and its application in oil and salt reduction. The Pickering emulsion comprises an outer aqueous phase, an oil phase, and an inner aqueous phase, homogenized by high-speed shearing. The outer aqueous phase is an aqueous solution containing 0%-5% sodium chloride and 2%-5% oxidized starch-gelatin nanoparticles; the oil phase is a mixture of edible oil and polyglycerol ricinoleic acid ester; and the inner aqueous phase is a sodium chloride aqueous solution with a mass fraction of 2%-10%. The emulsion constructed by this invention can release 90%-94% of sodium ions in the oral cavity. When added to sauces, it can reduce the amount of sodium chloride added by 20% while maintaining the perception of saltiness. Furthermore, while "reducing salt without reducing saltiness," it also has good oral lubrication properties and can replace 14.7%-20% of the added oil, showing good application prospects in reducing oil in food seasoning sauces.

Description

Technical Field

[0001] This invention belongs to the field of food oil and salt reduction technology, and specifically relates to a Pickering emulsion with oral pH and enzyme dual response, its preparation and application in oil and salt reduction. Background Technology

[0002] Chinese culinary culture has a long history, and sauces, as its essence and soul, are widely used in stir-frying, dipping, and cold dishes, playing a crucial role in shaping the flavor, color, and texture of dishes and grain-based foods. However, in pursuit of the ultimate taste experience and stability, traditional sauces often rely on high levels of salt, oil, and added sugar. Excessive long-term intake of sodium and fat has been recognized as a significant dietary risk factor for chronic non-communicable diseases such as hypertension, cardiovascular disease, and obesity. With the continued advancement of my country's "Healthy China 2030" and "Three Reductions and Three Healths" initiatives, and the increasing health literacy of the population, how to scientifically and effectively reduce the salt and oil content of sauces while preserving the sensory qualities of traditional Chinese food, such as flavor, taste, and texture, has become a critical technical bottleneck and a major issue that urgently needs to be addressed in the food industry, public health sector, and related industries.

[0003] Current practices in reducing salt and oil in sauces face multiple technical bottlenecks. Simply reducing the amount used can easily lead to a thin flavor, unbalanced taste, shortened shelf life, and a sharp drop in consumer acceptance. Salt not only provides saltiness but also has multiple functions such as enhancing umami, preservation, and regulating texture; oil contributes to a smooth texture, rich flavor, and appealing sheen, and serves as a carrier for fat-soluble flavor substances. Therefore, reducing salt and oil is not simply a matter of removing ingredients, but a systematic project involving flavor compensation, texture restructuring, stability reconstruction, and precise design of sensory experience. This urgently requires the introduction of innovative food materials science and delivery technologies, such as flavor-enhancing peptides, natural umami substances, microencapsulated salt / oil, emulsification gel technology, and novel emulsion carriers (such as Pickering emulsions and dual emulsions). These strategies can intelligently regulate the release behavior and perceived intensity of core ingredients in the oral cavity while reducing their content, thereby achieving the goal of "reducing salt without reducing flavor, and reducing oil without reducing quality."

[0004] The emulsion system mentioned above still faces technical challenges such as processing stability in oral taste perception and enhancement, as well as in food processing, especially heat processing. Therefore, it is of great significance to develop a seasoning sauce that has excellent salt and oil reduction effects, does not affect the flavor and taste of the food itself, and is suitable for heat-processed foods. Summary of the Invention

[0005] To overcome the shortcomings and deficiencies of the prior art, the primary objective of this invention is to provide a Pickering emulsion with both oral pH and enzyme responsiveness. The emulsion obtained by this invention can enhance the perception of saltiness by controlling the distribution of each component and promoting sodium ion penetration; and it compensates for the impact of reduced oil content on the smoothness of the mouthfeel through the lubricating effect of the emulsion.

[0006] Another object of the present invention is to provide a method for preparing the Pickering emulsion having both oral pH and enzyme responses.

[0007] Another object of the present invention is to provide the application of the Pickering emulsion with oral pH and enzyme dual response in the control of oil and salt intake.

[0008] The objective of this invention is achieved through the following solution:

[0009] A Pickering emulsion with oral pH and enzyme dual response, the Pickering emulsion comprising an external aqueous phase, an oil phase and an internal aqueous phase, formed by high-speed shear homogenization.

[0010] In the Pickering emulsion, relative to the total weight of the emulsion, the mass percentage of the external aqueous phase is 70-80 wt%, the mass percentage of the oil phase is 14-24 wt%, and the mass percentage of the internal aqueous phase is 4-9 wt%.

[0011] The external aqueous phase is an aqueous solution containing sodium chloride and oxidized starch-gelatin nanoparticles, wherein the mass fraction of oxidized starch-gelatin nanoparticles in the external aqueous phase is 2%-5%; and the mass fraction of sodium chloride is 0%-5%, preferably 0-0.69%.

[0012] The oil phase is a mixture of edible oil and polyglycerol ricinoleate, wherein the mass of polyglycerol ricinoleate is 2%-4% (w / w) of the mass of edible oil, preferably 3% (w / w).

[0013] The internal aqueous phase is a sodium chloride aqueous solution with a mass fraction of 2%-10%.

[0014] A method for preparing the above-mentioned Pickering emulsion with both oral pH and enzyme responsiveness includes the following steps:

[0015] (1) Preparation of oxidized starch-gelatin nanoparticles: Disperse oxidized starch in water, stir evenly and heat to gelatinize to obtain oxidized starch dispersion; disperse gelatin in water, stir evenly and heat to obtain gelatin dispersion; adjust the pH of the obtained oxidized starch dispersion and gelatin dispersion to the range of 4.8-5.0, and then mix and stir to obtain oxidized starch-gelatin nanoparticle dispersion;

[0016] (2) Preparation of Pickering emulsion: Prepare a sodium chloride aqueous solution with a mass concentration of 2-10 wt% as the inner aqueous phase, add polyglycerol ricinoleate with a mass of 2-4 wt% of the edible oil as the oil phase, mix the inner aqueous phase and the oil phase and shear at high speed to obtain emulsion 1; add sodium chloride and oxidized starch-gelatin nanoparticles to water to prepare an aqueous solution containing 0-5 wt% sodium chloride and 2-5 wt% oxidized starch-gelatin nanoparticles as the outer aqueous phase, mix emulsion 1 and the outer aqueous phase and shear homogenize to obtain a Pickering emulsion with both pH and enzyme response.

[0017] In step (1), dispersing oxidized starch in water means preparing a dispersion of 5-10 wt%; the heating and gelatinization mentioned in step (1) means heating and gelatinizing at 90-95℃ for 30-35 minutes.

[0018] The weight-average molecular weight of the oxidized starch mentioned in step (1) is 7.82 × 10⁻⁶. 5 g / mol - 8.02 × 10 5 The gelatin has a g / mol content and a carboxyl content of 1.1%; the weight-average molecular weight of the gelatin is 0.94 × 10⁻⁶ g / mol. 5 g / mol - 1.71 × 10 5 g / mol, the isoelectric point of gelatin is 5.5-6.2.

[0019] The dispersing of gelatin in water in step (1) refers to preparing a dispersion of 5-10 wt%; the heating treatment in step (1) refers to heating at 45-140℃ for 15-20 minutes.

[0020] The mass ratio of the oxidized starch dispersion and the gelatin dispersion in step (1) is 1:1 to 4:1, preferably 3:1.

[0021] The mixing and stirring mentioned in step (1) refers to stirring at 600-750 rpm for 20-24 hours at room temperature.

[0022] The oxidized starch-gelatin nanoparticles obtained in step (1) have a contact angle of 85°-89°, a particle size of 150nm-280nm, and thermal stability at 25-120℃.

[0023] The edible oil mentioned in step (2) includes, but is not limited to, sunflower oil, corn oil, soybean oil, and other edible oils.

[0024] The high-speed shearing to obtain emulsion 1 mentioned in step (2) refers to shearing at a speed of 10000-14000 rpm for 2-4 minutes; the shearing homogenization mentioned in step (2) refers to shearing at a speed of 8000-9500 rpm for 2-4 minutes, followed by high-pressure homogenization at a pressure of 500-650 bar for 3-5 minutes.

[0025] The Pickering emulsion, which has both pH and enzyme responses, releases 80%-94% of its sodium chloride within 5 minutes when the pH changes to 6.8 and artificial saliva is added, with a friction coefficient of 0.08-0.24.

[0026] The Pickering emulsion with both pH and enzyme responses, after being heated at 80-100℃ for 20-30 minutes, exhibits a particle size change from 0.71-0.92μm to 1.12-1.52μm and a friction coefficient of 0.095-0.21, demonstrating good thermal stability.

[0027] The above-mentioned Pickering emulsion with both pH and enzyme responsiveness is used in the preparation of food seasonings with reduced oil and salt content. Replacing a portion of the seasoning sauce with the aforementioned Pickering emulsion at a mass ratio of 23%-27% can reduce both oil and salt content by 15%-20% while maintaining the perceived saltiness and smooth texture.

[0028] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0029] 1. The emulsion constructed in this invention has good thermal stability during thermal processing and is suitable for thermally processed products.

[0030] 2. The emulsion constructed in this invention can release 90%-94% sodium ions in the oral cavity, and when added to sauces, it can reduce the amount of sodium chloride added by 20% while maintaining the perception of saltiness.

[0031] 3. The emulsion constructed in this invention not only reduces salt content but also has good oral lubrication properties, and can replace 14.7%-20% of the amount of added oil, showing good application prospects in reducing oil in food seasoning sauces. Attached Figure Description

[0032] Figure 1 The figures show the particle size test results of the emulsions in Examples 1-4. (A), (B), and (C) represent the particle size test results of the original emulsion, the emulsion after heat treatment, and the emulsion under pH 6.8 conditions, respectively.

[0033] Figure 2The images show the laser confocal test results for Examples 1-4. (A) shows the microstructure of Example 1 before heat treatment; (B) shows the microstructure of Example 1 after heat treatment; (C) shows the microstructure of Example 2 before heat treatment; (D) shows the microstructure of Example 2 after heat treatment; (E) shows the microstructure of Example 3 before heat treatment; (F) shows the microstructure of Example 3 after heat treatment; (G) shows the microstructure of Example 4 before heat treatment; and (H) shows the microstructure of Example 4 after heat treatment.

[0034] Figure 3 The following are Stribeck oral friction curves for the emulsions of Examples 1-4. (A) is the Stribeck friction curve after Examples 1-4 are mixed with artificial saliva at a mass ratio of 1:1; (B) is the Stribeck friction curve after mixtures of soybean oil and water with different mass fractions are mixed with saliva.

[0035] Figure 4 The following are the sodium ion release curves for Examples 1-4. (A) Sodium ion release curves for Examples 1-4 after mixing with deionized water at pH 6.8. (B) Sodium ion release curves for Examples 1-4 after mixing with artificial saliva.

[0036] Figure 5 The Stribeck friction curves are shown for the seasoning sauce with 20% less salt and seasoning sauces with different oil contents in Example 5.

[0037] Figure 6 The images show the appearance of the comparative examples and Examples 1-4 after standing for 24 hours. Detailed Implementation

[0038] The present invention will be further described in detail below with reference to embodiments and accompanying drawings, but the embodiments of the present invention are not limited thereto. Unless otherwise specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall apply. Reagents or instruments used, unless otherwise specified, are all commercially available conventional products.

[0039] Structure and performance characterization of W / O / W Pickering emulsions in the examples:

[0040] (1) Emulsion particle size test: The particle size distribution and volume average diameter of W / O / W Pickering were determined using Mastersizer 3000. The emulsion was dispersed in a dispersant (deionized water) with the following parameters: particle absorptivity 0.001, particle refractive index 1.470, dispersant refractive index 1.330, and water was used as the dispersant. The sample was automatically tested three times. The particle size and particle size distribution of W / O / W Pickering were determined by the volume average diameter d4,3.

[0041] (2) Observation of the microstructure of the emulsion: The oil phase, external aqueous phase, and internal aqueous phase of the W / O / W Pickering emulsion were stained and then observed by laser confocal microscopy. The oil phase was stained with 0.2% wt Nile Red, with an Nile Red dosage of 4.8 μL / g. The Na+ in the internal and external aqueous phases was also observed. + Staining was performed using sodium fluorescein, with the amount of sodium fluorescein used being 0.1% wt% of the mass of both the external and internal aqueous phases. The stained W / O / W Pickering emulsion was prepared according to the corresponding example. It was placed in the dark for 2 hours to allow for complete staining. A small amount of the stained emulsion was then applied to a glass slide, which was covered with a coverslip. A ring of glycerol was applied around the slide to prevent moisture evaporation. The slide was then inverted on the stage for observation. The corresponding excitation wavelengths were set: 488 nm for sodium fluorescein and Nile red; the detection channel for sodium fluorescein was set to 500-550 nm; and the detection channel for Nile red was set to 570-620 nm. The scan frequency was set to 100 Hz, the scan density to 1024 × 1024, and the magnification to 62x.

[0042] (3) Tribological performance test of emulsion: The tribological properties of the emulsion samples were determined using a rheometer equipped with a ball-and-plate friction device. The ball-and-plate friction device consists of a rigid ball and a disc specimen with three small stainless steel plates attached. The tribological performance was determined by rotating the disc specimen around the central axis of the disc. The diameter of the ball used in this study was 12.7 mm, the size of the small plates was 4 mm × 4 mm × 15 mm, the sample addition amount was 400 μL, the normal load was 2.0 N, and the coefficient of friction of the sample was determined under the conditions of 37 °C and a carrying rate of 0.1–100.0 mm / s.

[0043] (4) Detection of sodium ion release rate of emulsion: The emulsion was mixed with an aqueous solution of pH 6.8 and saliva (Yuanye R41109 artificial saliva, pH=6.8) at a mass ratio of 1:1. A magnetic stirrer was used to simulate the movement of liquid in the oral cavity at a speed of 800 rpm and a temperature of 37°C. The sodium ion concentration was measured in real time using a sodium ion meter and recorded every 10 seconds. The sodium ion release rate under the conditions of pH 6.8 and simulated saliva was calculated.

[0044] (5) Sensory evaluation test:

[0045] Personnel selection: Citric acid solution (0.1 wt%), alum solution (0.05 wt%), glucose solution (1.0 wt%), monosodium glutamate solution (0.10 wt%), and sodium chloride solution (0.35 wt%) were prepared and then randomly distributed to volunteers for tasting. Fifteen volunteers (aged 23 to 30) who were able to correctly judge the taste of the above solutions were selected.

[0046] Personnel Training: Selected volunteers abstained from stimulating foods (e.g., spicy, high-sugar, or caffeinated foods) for 2 hours prior to the formal experiment to reduce taste interference. For the quantitative saltiness analysis, the selected volunteers underwent training. First, salt concentrations of different standard NaCl solutions were assigned scores: 0.5%, 0.6%, 0.7%, 0.8%, and 0.9%, corresponding to saltiness scores of 1, 2, 3, 4, and 5 points, respectively. Volunteers were required to quantify the saltiness intensity of the unknown sample using a comparative method, using a reference solution as a baseline. Each volunteer held 5 mL of the sample solution in their mouth for 10 seconds, then spat it out, rinsing their mouth thoroughly with water for 2 minutes between each sampling, with a 35-second rest period provided. The team members determined the saltiness score of the sample by repeatedly comparing the saltiness intensity with the reference NaCl solution.

[0047] (6) Electronic tongue flavor test: The SA402B electronic tongue instrument was used for detection. The sensor was first cleaned in the cleaning solution for 90s, then cleaned in the reference solution for 120s, and then cleaned in another reference solution for 120s. The sensor was zeroed at the equilibrium position for 30s. Test: The test time was 30s, and the initial taste value was output; then the sensor was cleaned in the reference solution for 3s, and the aftertaste was tested in the new reference solution for 30s. The five food taste sensors C00, AE1, CA0, CT0, AAE and the bitter taste sensors ANO, BTO were tested 4 times. The first cycle was removed and the average of the last three cycles was taken as the test result.

[0048] Example 1:

[0049] (1) Preparation of oxidized starch-gelatin nanoparticles: Oxidized starch-gelatin nanoparticles with a carboxyl content of 1.1% and a weight-average molecular weight of 7.82 × 10⁻⁶ were prepared. 5 Oxidized starch (g / mol) was dispersed in water to prepare a 10wt% dispersion. After uniform dispersion, it was gelatinized by heating at 95℃ for 30 minutes. A starch with an isoelectric point of 5.5 and a weight-average molecular weight of 0.94 × 10⁻⁶ g / mol was then used. 5A 10wt% dispersion of g / mol gelatin was prepared by dispersing the gelatin in water. After uniform dispersion, the solution was heated at 120°C for 15 minutes. The pH of the obtained oxidized starch dispersion and gelatin dispersion were adjusted to 4.8 with 2mol / L hydrochloric acid solution. Then, the oxidized starch dispersion and gelatin dispersion were mixed and stirred at 650 rpm for 20 hours at a mass ratio of 3:1 to obtain an oxidized starch-gelatin nanoparticle dispersion. The precipitate was collected by centrifugation and freeze-dried for 48 hours to obtain nanoparticle powder.

[0050] (2) Preparation of Pickering emulsion: An emulsion was prepared by mixing an inner aqueous phase, an oil phase, and an outer aqueous phase in a mass ratio of 6:24:70. The specific method is as follows: a 2 wt% sodium chloride aqueous solution was prepared as the inner aqueous phase; soybean oil containing 3 wt% polyglycerol ricinoleate was prepared as the oil phase; and an aqueous solution containing 0.69 wt% sodium chloride and 2.5 wt% nanoparticles was prepared as the outer aqueous phase. 6 g of the inner aqueous phase was added to 24 g of the oil phase, and the shear rate was adjusted to 12000 rpm for 3 min. The above emulsion was poured into 70 g of the outer aqueous phase, and the shear rate was adjusted to 8000 rpm for 3 min. The mixture was then homogenized under high pressure at 550 bar for 3 min to obtain a W / O / W Pickering emulsion with an inner aqueous phase containing 2 wt% sodium chloride, an outer aqueous phase containing 0.69 wt% sodium chloride and 2.5 wt% nanoparticles, and an inner-oil-outer ratio of 6:24:70.

[0051] like Figure 1 As shown, the emulsion in this embodiment, when tested in a particle size analyzer at pH 4.8, had a particle size of 0.71 μm. The small particle size is beneficial for maintaining the stable structure of the emulsion. After heating in an oil bath at 100°C for 20 minutes, the emulsion particle size decreased to 1.12 μm, showing minimal change and indicating good thermal stability. Testing in a particle size analyzer at pH 6.8 revealed a significant increase in particle size, increasing to 4 μm, demonstrating pH responsiveness. Figure 2 As can be seen from the laser confocal image, the emulsion prepared in this embodiment has a W / O / W type emulsion structure. Heating (100℃ oil bath heating for 20 minutes) has little effect on the emulsion structure and size, and the emulsion has good thermal stability. Figure 3 As shown in the Stribeck friction curves, the friction coefficient of the emulsion prepared in this embodiment, when mixed with saliva (Yuan Ye R41109 artificial saliva, pH=6.8) at a mass ratio of 1:1, is between 0.99 and 0.21, which is relatively low. The emulsion prepared in this embodiment contains 24% oil phase, and its friction coefficient is close to that of an oil-water mixture containing 30% soybean oil (0.088-0.22), indicating that the emulsion prepared in this embodiment can reduce oil content by nearly 20% while maintaining a smooth mouthfeel. Figure 4As shown, the emulsion prepared in this embodiment, when mixed at a mass ratio of 1:1 with deionized water (pH 6.8) and simulated saliva (Yuan Ye R41109 artificial saliva, pH=6.8), released 86% and 94% of sodium ions respectively within 5 minutes. This indicates that the emulsion prepared in this embodiment exhibits both pH and enzyme responsiveness. According to the sensory evaluation test results in Table 1, the emulsion prepared in this embodiment can reduce the amount of sodium chloride added by 19.46%. In summary, this embodiment can reduce the amount of sodium chloride added by nearly 20% and the amount of edible oil added by 20% while maintaining flavor perception.

[0052]

[0053] Example 2:

[0054] (1) Oxidized starch-gelatin nanoparticles were prepared according to the method and conditions of step (1) in Example 1.

[0055] (2) Preparation of Pickering emulsion: An emulsion was prepared by mixing an inner aqueous phase, an oil phase, and an outer aqueous phase in a mass ratio of 6:24:70. The specific method is as follows: a 10 wt% sodium chloride solution was prepared as the inner aqueous phase; soybean oil containing 3 wt% polyglycerol ricinoleate was prepared as the oil phase; and a solution containing 0 wt% sodium chloride and 3 wt% nanoparticles was prepared as the outer aqueous phase. 6 g of the inner aqueous phase was added to 24 g of the oil phase, and the shear rate was adjusted to 12000 rpm and sheared at high speed for 3 min. The above emulsion was poured into 70 g of the outer aqueous phase, and the shear rate was adjusted to 8000 rpm and sheared at high speed for 3 min. The emulsion was then homogenized at 550 bar for 3 min. A W / O / W Pickering emulsion was obtained with an inner aqueous phase containing 10 wt% sodium chloride, an outer aqueous phase containing 0 wt% sodium chloride and 3 wt% nanoparticles, and an inner-oil-outer ratio of 6:24:70.

[0056] like Figure 1 As shown, the emulsion in this embodiment, when tested in a particle size analyzer at pH 4.8, had a particle size of 0.72 μm. The small particle size is beneficial for maintaining the stable structure of the emulsion. After heating in an oil bath at 100°C for 20 minutes, the emulsion particle size decreased to 1.55 μm, showing minimal change and good thermal stability. Testing in a particle size analyzer at pH 6.8 revealed a significant increase in particle size to 7.36 μm, indicating that the emulsion exhibits oral pH responsiveness. Figure 2 As can be seen from the laser confocal image, a W / O / W type emulsion structure has been formed in this embodiment. Heating (100℃ oil bath heating for 20 minutes) has little effect on the emulsion structure and size, and the emulsion exhibits good thermal stability. Figure 3As shown in the Stribeck friction curve, the coefficient of friction of the emulsion prepared in this embodiment, when mixed with saliva (Yuan Ye R41109 artificial saliva, pH=6.8) at a mass ratio of 1:1, is between 0.10 and 0.23, exhibiting a low coefficient of friction. This embodiment contains 24% oil, and its coefficient of friction falls within the range of oil-water mixtures containing 28% or 30% soybean oil. This embodiment can replace approximately 14.7%-20% of the oil while maintaining a smooth mouthfeel. Figure 4 As shown, the emulsion prepared in this embodiment, when mixed at a mass ratio of 1:1 with deionized water (pH 6.8) and simulated saliva (Yuan Ye R41109 artificial saliva, pH=6.8), released 80.33% and 93.33% of sodium ions respectively within 5 minutes, demonstrating that this embodiment exhibits both pH and enzyme responsiveness. According to the sensory evaluation test results in Table 1, this embodiment can replace approximately 14.7% of the salt. In summary, this embodiment can reduce the amount of added sodium chloride by approximately 14.7% and the amount of added edible oil by 14.7%-20% while maintaining flavor perception.

[0057] Example 3:

[0058] (1) Prepare oxidized starch-gelatin nanoparticles according to step (1) of Example 1.

[0059] (2) Preparation of Pickering emulsion: An emulsion was prepared by mixing the inner aqueous phase, oil phase, and outer aqueous phase in a mass ratio of 6:14:80. The specific method is as follows: a 10wt% sodium chloride solution was prepared as the inner aqueous phase; soybean oil containing 3wt% polyglycerol ricinoleate was prepared as the oil phase; and an aqueous solution containing 0wt% sodium chloride and 2.5wt% nanoparticles was prepared as the outer aqueous phase. 6g of the inner aqueous phase was added to 14g of the oil phase, and the shear rate was adjusted to 12000rpm and sheared at high speed for 3min. The above emulsion was poured into 80g of the outer aqueous phase solution, and the shear rate was adjusted to 8000rpm and sheared at high speed for 3min, followed by high-pressure homogenization at 550bar for 3min. A W / O / W Pickering emulsion was obtained with an inner aqueous phase containing 10wt% sodium chloride, an outer aqueous phase containing 0wt% sodium chloride and 2.5wt% nanoparticles, and an inner-oil-outer ratio of 6:14:80.

[0060] like Figure 1 As shown, in this embodiment, the emulsion, when tested in a particle size analyzer at pH 4.8, had a particle size of 0.92 μm. The small particle size is beneficial for maintaining the stable structure of the emulsion. After heating in an oil bath at 100°C for 20 minutes, the emulsion particle size decreased to 1.44 μm, showing minimal change and good thermal stability. Testing in a particle size analyzer at pH 6.8 revealed a significant increase in particle size to 6.87 μm, indicating that the emulsion exhibits oral pH responsiveness. Figure 2As can be seen from the laser confocal image, a W / O / W type emulsion structure has been formed in this embodiment. Heating (100℃ oil bath heating for 20 minutes) has little effect on the emulsion structure and size, and the emulsion exhibits good thermal stability. Figure 3 As shown in the Stribeck friction curves, the coefficient of friction of the emulsion prepared in this embodiment, when mixed with saliva (Yuan Ye R41109 artificial saliva, pH=6.8) at a mass ratio of 1:1, is between 0.11 and 0.23, exhibiting a low coefficient of friction. The emulsion prepared in this embodiment contains 24% oil, and its coefficient of friction is close to that of an oil-water mixture containing 28% soybean oil (0.13-0.24). This embodiment can replace approximately 14.7% of the oil while maintaining a smooth mouthfeel. Figure 4 As shown, the emulsion prepared in this embodiment, when mixed at a mass ratio of 1:1 with deionized water (pH 6.8) and simulated saliva (Yuan Ye R41109 artificial saliva, pH=6.8), released 85% and 95.33% of sodium ions respectively within 5 minutes, demonstrating that this embodiment exhibits both pH and enzyme responsiveness. According to the sensory evaluation test results in Table 1, this embodiment can replace approximately 14.7% of the salt. In summary, this embodiment can reduce the amount of added sodium chloride by 14.7% and the amount of added edible oil by 14.7% while maintaining flavor perception.

[0061] Example 4:

[0062] (1) Prepare oxidized starch-gelatin nanoparticles according to step (1) of Example 1.

[0063] (2) Preparation of Pickering emulsion: An emulsion was prepared by mixing the inner aqueous phase, oil phase, and outer aqueous phase in a mass ratio of 6:24:70. The specific method is as follows: a 10wt% sodium chloride solution was prepared as the inner aqueous phase; soybean oil containing 3wt% polyglycerol ricinoleate was prepared as the oil phase; and an aqueous solution containing 0wt% sodium chloride and 2.5wt% nanoparticles was prepared as the outer aqueous phase. 6g of the inner aqueous phase was added to 24g of the oil phase, and the shear rate was adjusted to 12000rpm and sheared at high speed for 3min. 30g of the above emulsion was poured into 70g of the outer aqueous phase solution, and the shear rate was adjusted to 8000rpm and sheared at high speed for 3min, followed by high-pressure homogenization at 550bar for 3min. A W / O / W Pickering emulsion was obtained with an inner aqueous phase containing 10% (w / w) sodium chloride and an outer aqueous phase containing 0% (w / w) sodium chloride and 2.5% (w / w) nanoparticles, and an inner-oil-outer ratio of 6:24:70.

[0064] like Figure 1As shown, the emulsion in this embodiment, when tested in a particle size analyzer at pH 4.8, had a particle size of 0.92 μm. The small particle size is beneficial for maintaining the stable structure of the emulsion. After heating in an oil bath at 100°C for 20 minutes, the emulsion particle size decreased to 1.47 μm, showing minimal change and good thermal stability. Testing in a particle size analyzer at pH 6.8 revealed a significant increase in particle size to 5.63 μm, indicating that the emulsion exhibits oral pH responsiveness. Figure 2 As can be seen from the laser confocal image, a W / O / W type emulsion structure has been formed in this embodiment. Heating (100℃ oil bath heating for 20 minutes) has little effect on the emulsion structure and size, and the emulsion exhibits good thermal stability. Figure 3 As shown in the Stribeck friction curve, the coefficient of friction of the emulsion prepared in this embodiment, when mixed with saliva (Yuan Ye R41109 artificial saliva, pH=6.8) at a mass ratio of 1:1, is between 0.11 and 0.22, exhibiting a low coefficient of friction. This embodiment contains 24% oil, and its coefficient of friction falls between that of oil-water mixtures containing 28% and 30% soybean oil. This embodiment can replace approximately 14.7%-20% of the oil while maintaining a smooth mouthfeel. Figure 4 As shown, the emulsion prepared in this embodiment, when mixed at a mass ratio of 1:1 with deionized water at pH 6.8 and simulated saliva (Yuan Ye R41109 artificial saliva, pH=6.8), released 84.33% and 95% of sodium ions respectively within 5 minutes, demonstrating that this embodiment exhibits both pH and enzyme responsiveness. According to the sensory evaluation test results in Table 1, this embodiment can replace nearly 20% of the salt. In summary, this embodiment can reduce the amount of added sodium chloride by nearly 20% and the amount of added edible oil by 14.7%-20% while maintaining flavor perception.

[0065] Example 5:

[0066] Mix the mushroom-flavored dark soy sauce (sodium content 1280mg / 15ml), oyster sauce (sodium content 642mg / 15ml), and the emulsion from Example 4 (sodium content 36mg / 15ml), add warm water to 100g, and stir well to obtain seasoning sauces with reduced salt content of 20%, 25%, and 30%. The specific amounts of mushroom-flavored dark soy sauce, oyster sauce, and emulsion added are shown in Table 2.

[0067]

[0068] The results of the electronic tongue taste response are shown in Table 3. The saltiness perception value of the seasoning sauce with 20% less salt was not significantly different from that of the control group, indicating that adding the emulsion of the present invention can reduce the amount of sodium chloride added by 20% while maintaining the original saltiness perception.

[0069] To compare the coefficient of friction of a seasoning sauce with 20% less salt with that of seasoning sauces with different oil contents, seasoning sauces with different oil contents were prepared. For example, the recipe for a seasoning sauce with 7.0% oil content is: 93g of original seasoning sauce and 7g of soybean oil. Original seasoning sauces with oil contents of 7.5%, 8.0%, and 8.5% were prepared using the same method.

[0070] Depend on Figure 5 The friction curves show that the friction coefficient of a seasoning sauce with 20% less salt is between that of a seasoning sauce with 7.5%-8.0% oil content. Without affecting the friction performance, a seasoning sauce with 20% less salt can reduce oil content by 15%-20%.

[0071] Table 3. Electronic tongue taste response values ​​for low-sodium seasoning sauce

[0072]

[0073] Comparative example:

[0074] The carboxyl content was 1.1%, and the weight average molecular weight was 7.82 × 10⁻⁶. 5 Oxidized starch (g / mol) was dispersed in water to prepare a 10wt% dispersion. After thorough stirring, it was heated at 95℃ for 30 minutes to gelatinize. The pH of the obtained oxidized starch dispersion was adjusted to 4.8 with 2mol / L hydrochloric acid solution, and the mixture was stirred for 20 hours to obtain the oxidized starch dispersion. An emulsion was prepared by mixing the inner aqueous phase, oil phase, and outer aqueous phase in a mass ratio of 6:24:70, as follows: a 10wt% sodium chloride solution was prepared as the inner aqueous phase; 3wt% soybean oil containing polyglycerol ricinoleate was prepared as the oil phase; and a solution of 0wt% sodium chloride and 2.5wt% oxidized starch was prepared as the outer aqueous phase (i.e., the oxidized starch dispersion obtained in the previous step was directly diluted to 2.5wt%). 6g of the inner aqueous phase was slowly added to 24g of the oil phase, and the shear rate was adjusted to 12000rpm for high-speed shearing for 3min. 30g of the above emulsion was poured into 70g of the outer aqueous phase solution, and the shear rate was adjusted to 8000rpm for high-speed shearing for 3min, followed by high-pressure homogenization for 3min. A W / O / W Pickering emulsion was obtained with an inner aqueous phase containing 10% (w / w) sodium chloride and an outer aqueous phase containing 0% (w / w) sodium chloride and 2.5% (w / w) oxidized starch, and an inner-oil-outer-oil ratio of 6:24:70.

[0075] from Figure 6 The appearance diagrams of the comparative examples and Examples 1-4 show that the emulsions in the comparative examples exhibited significant stratification after 24 hours of storage, indicating poor emulsion stability. This demonstrates that gelatinized oxidized starch alone cannot form a stable W / O / W emulsion.

[0076] The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above embodiments. Any changes, modifications, substitutions, combinations, or simplifications made without departing from the spirit and principle of the present invention shall be considered equivalent substitutions and shall be included within the protection scope of the present invention.

Claims

1. A Pickering emulsion with both oral pH and enzyme responsiveness, characterized in that... The Pickering emulsion comprises an external aqueous phase, an oil phase, and an internal aqueous phase; The external aqueous phase is an aqueous solution containing sodium chloride and oxidized starch-gelatin nanoparticles, wherein the mass fraction of oxidized starch-gelatin nanoparticles in the external aqueous phase is 2%-5%; and the mass fraction of sodium chloride is 0%-5%. The oil phase is a mixture of edible oil and polyglycerol ricinoleate, wherein the mass of polyglycerol ricinoleate is 2-4% of the mass of edible oil; The internal aqueous phase is a sodium chloride aqueous solution with a mass fraction of 2%-10%.

2. The Pickering emulsion with oral pH and enzyme dual response according to claim 1, characterized in that: In the Pickering emulsion, relative to the total weight of the emulsion, the mass percentage of the external aqueous phase is 70-80 wt%, the mass percentage of the oil phase is 14-24 wt%, and the mass percentage of the internal aqueous phase is 4-9 wt%.

3. A method for preparing a Pickering emulsion with both oral pH and enzyme responsiveness according to claim 1 or 2, characterized in that... Includes the following steps: (1) Preparation of oxidized starch-gelatin nanoparticles: Disperse oxidized starch in water, stir evenly and heat to gelatinize to obtain oxidized starch dispersion; disperse gelatin in water, stir evenly and heat to obtain gelatin dispersion; adjust the pH of the obtained oxidized starch dispersion and gelatin dispersion to the range of 4.8-5.0, and then mix and stir to obtain oxidized starch-gelatin nanoparticle dispersion; (2) Preparation of Pickering emulsion: Prepare a sodium chloride aqueous solution with a mass concentration of 2-10 wt% as the inner aqueous phase, add polyglycerol ricinoleate with a mass of 2-4 wt% of the edible oil as the oil phase, mix the inner aqueous phase and the oil phase and shear at high speed to obtain emulsion 1; add sodium chloride and oxidized starch-gelatin nanoparticles to water to prepare an aqueous solution containing 0-5 wt% sodium chloride and 2-5 wt% oxidized starch-gelatin nanoparticles as the outer aqueous phase, mix emulsion 1 and the outer aqueous phase and shear homogenize to obtain a Pickering emulsion with both pH and enzyme response.

4. The method for preparing Pickering emulsion with oral pH and enzyme dual response according to claim 3, characterized in that: In step (1), dispersing oxidized starch in water means preparing a dispersion of 5-10 wt%; the heating and gelatinization mentioned in step (1) means heating and gelatinizing at 90-95℃ for 30-35 minutes. The weight-average molecular weight of the oxidized starch mentioned in step (1) is 7.82 × 10⁻⁶. 5 g / mol - 8.02 × 10 5 The gelatin has a g / mol content and a carboxyl content of 1.1%; the weight-average molecular weight of the gelatin is 0.94 × 10⁻⁶ g / mol. 5 g / mol - 1.71 × 10 5 g / mol, the isoelectric point of gelatin is 5.5-6.2; The dispersing of gelatin in water in step (1) refers to preparing a dispersion of 5-10 wt%; the heating treatment in step (1) refers to heating at 45-140℃ for 15-20 minutes.

5. The method for preparing Pickering emulsion with oral pH and enzyme dual response according to claim 3, characterized in that: The mass ratio of the oxidized starch dispersion and the gelatin dispersion mentioned in step (1) is 1:1 to 4:1; The mixing and stirring mentioned in step (1) refers to stirring at 600-750 rpm for 20-24 hours at room temperature.

6. The method for preparing Pickering emulsion with oral pH and enzyme dual response according to claim 3, characterized in that: The contact angle of the oxidized starch-gelatin nanoparticles obtained in step (1) is 85°-89° and the particle size is 150nm-280nm.

7. The method for preparing Pickering emulsion with oral pH and enzyme dual response according to claim 3, characterized in that: The edible oil mentioned in step (2) is at least one of sunflower seed oil, corn oil, and soybean oil.

8. The method for preparing Pickering emulsion with oral pH and enzyme dual response according to claim 3, characterized in that: The high-speed shearing to obtain emulsion 1 mentioned in step (2) refers to shearing at a speed of 10000-14000 rpm for 2-4 minutes; the shearing homogenization mentioned in step (2) refers to shearing at a speed of 8000-9500 rpm for 2-4 minutes, followed by high-pressure homogenization at a pressure of 500-650 bar for 3-5 minutes.

9. The application of the Pickering emulsion with oral pH and enzyme dual response as described in claim 1 or 2 in the preparation of oil and salt-controlled food flavoring.

10. The application of the Pickering emulsion with oral pH and enzyme dual response according to claim 9 in the preparation of food flavorings with reduced oil and salt content, characterized in that... The Pickering emulsion, which has both pH and enzyme responses, replaces a portion of the flavoring sauce at a mass ratio of 20%-30%.

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