Preparation method of yoghourt based on pea protein-stevioside nano-emulsion
By preparing pea protein-stevia glycoside nanoemulsion, the problems of loose texture, whey separation, and poor flavor in fat-free and sugar-free yogurt were solved. A dense gel network was formed, which improved the texture and flavor of the yogurt and increased consumer acceptance.
Patent Information
- Application Number
- CN202511875957.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-12-12
- Publication Date
- 2026-01-13
AI Technical Summary
Existing fat-free and sugar-free yogurts suffer from quality defects such as loose texture, easy whey separation, rough taste, and sour flavor due to the lack of fat backbone and sugar substances. Furthermore, the interfacial film formed by pea protein at the oil-water interface is not strong enough to effectively resist emulsion aggregation and Ostwald ripening.
Pea protein-stevioside nanoemulsion was used as a composite system. The nanoemulsion was prepared through magnetic stirring, heating and fermentation. Combining the amphiphilic structure of pea protein and the hydrophobic and hydrophilic properties of steviol glycoside, a dense gel network was formed, which improved the texture and masked the beany taste.
It achieves textural improvement and flavor enhancement in fat-free and sugar-free yogurt, forming a dense gel network to prevent whey separation, providing a rich taste, masking unpleasant flavors, and improving overall sensory quality.
Smart Images
Figure CN121312698A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of food processing technology, specifically relating to a method for preparing a nanoemulsion based on pea protein and steviol glycosides and its application in fat-free and sugar-free yogurt. Background Technology
[0002] Yogurt is a gel-like or semi-solid dairy product made primarily from milk through the co-fermentation of specific lactic acid bacteria (such as Lactobacillus bulgaricus and Streptococcus thermophilus). Yogurt is not only rich in high-quality protein, bioavailable calcium, and B vitamins, but the fermentation process also reduces lactose content, helping to alleviate lactose intolerance symptoms. Fat and sugar, as key components of yogurt, directly affect the product's rheology, texture, flavor, and mouthfeel. Fat contributes to the smooth texture and full-bodied flavor of yogurt by forming emulsions and crystalline networks, while sugar not only provides sweetness to balance acidity but also participates in the Maillard reaction and fermentation process, influencing the sensory characteristics of the final product.
[0003] However, with increasing consumer health awareness, excessive intake of fat and sugar has been proven to be associated with health problems such as obesity, diabetes, and cardiovascular disease. Therefore, developing low-fat or fat-free, sugar-free yogurt has become an important research direction in the dairy industry. However, reducing fat and removing sugar often leads to a series of quality defects in yogurt. The absence of fat weakens the viscosity, consistency, and smoothness of yogurt, easily causing whey separation and a loose texture; while the removal of sugar results in a prominent sour taste and insufficient sweetness, reducing the overall acceptability of the product. To address these issues, vegetable oils with low unsaturated fatty acids are widely used in low-fat foods to mimic the sensory and functional properties of fat; simultaneously, natural low-calorie sweeteners can be used to compensate for flavor deficiencies. However, most vegetable oils have low melting points and remain liquid at room temperature, while milk fat is solid under environmental conditions. This difference in physical state can adversely affect product quality. Therefore, the method of adding oil should be changed to improve product quality.
[0004] In recent years, plant protein-based nanoemulsion technology has attracted attention due to its natural, sustainable, and functional versatility. Pea protein (PPI), as a high-quality plant protein, boasts advantages such as comprehensive nutrition (biological value 48%-64%, efficacy ratio 0.6-1.2, rich in essential amino acids like lysine), low allergenicity, and compliance with clean label requirements. More importantly, pea protein possesses a typical amphiphilic structure, allowing it to adsorb at the oil-water interface and form a dense network through hydrophobic interactions, thus acting as a natural emulsifier to improve the stability, texture, and sensory quality of the system. Furthermore, steviol glycosides (STEs), a high-sweetness, low-calorie natural sweetener extracted from stevia leaves, not only effectively replace sugars but also possess bioactivities such as hypotensive, hypoglycemic, antibacterial, and immunomodulatory effects. Their molecular structures (such as rebaudioside A) simultaneously contain a hydrophobic portion (diterpene skeleton) and a hydrophilic portion (glucose unit), exhibiting significant amphiphilic properties, enabling them to act as a biosurfactant synergistically with plant proteins.
[0005] Currently, the application of pea protein in low-fat or sugar-free yogurt systems still faces several technical limitations. First, when used as a single emulsifier, the interfacial film formed at the oil-water interface is insufficiently strong, failing to effectively resist emulsion aggregation and Ostwald ripening, leading to phase separation and decreased stability during storage or processing. Second, under fat-free and sugar-free conditions, pea protein itself struggles to construct a complete and dense gel network, resulting in a coarse texture, whey separation, and a thin mouthfeel. Furthermore, due to the lack of synergistic flavor effects from fat and sugar, using pea protein alone is insufficient to mask any potential beany or unpleasant aftertaste, impacting flavor profile and consumer acceptance. Therefore, developing a pea protein composite system that synergistically enhances interfacial stability, improves gel performance, and optimizes flavor has become a pressing technical challenge in this field. Summary of the Invention
[0006] To address the quality defects of existing fat-free and sugar-free yogurts, such as loose texture, easy whey separation, rough mouthfeel, and sharp, sour flavor due to the lack of fat backbone and carbohydrates, this invention provides a yogurt based on pea protein-stevia glycoside nanoemulsion and its preparation method. This invention aims to simultaneously improve the texture and enhance the flavor of fat-free and sugar-free yogurt through a purely natural ingredient system, producing a healthy dairy product with both excellent sensory quality and a clean label.
[0007] The technical solution of the present invention is as follows: A method for preparing low-fat, sugar-free yogurt based on pea protein-stevia glycoside nanoemulsion, comprising the following steps: 1) Place the skim milk powder in a container, add distilled water to prepare a 1% to 5% solution, add pea protein-stevia glycoside nanoemulsion, and stir magnetically for at least 20 minutes to mix it evenly; 2) Place the solution in a water bath and heat at 80-85°C for 15 minutes. After pasteurization, cool to 40-43°C and add 0.004%-0.008% w / v of starter culture. Stir magnetically to mix evenly. 3) Transfer the above mixture to a constant temperature incubator at 42-45℃ for fermentation for 4-8 hours. Then transfer the yogurt to a refrigerator at 4-8℃ and allow it to mature for 10-24 hours to obtain yogurt containing pea protein-stevia glycoside nanoemulsion.
[0008] Preferably, the proportion of pea protein-stevia glycoside nanoemulsion added in step 1) is 0.5% to 2% of the solution volume.
[0009] Preferably, the components of the pea protein-stevioside nanoemulsion added in step 1) include: pea protein at a mass / volume concentration of 1% to 5%, steviol glycoside at a mass / volume concentration of 0.1% to 1%, and soybean oil at a mass / volume concentration of 10% to 30% w / v, with the balance being distilled water.
[0010] Preferably, the pea protein-stevioside nanoemulsion added in step 1) is prepared by the following method: (1) Preparation of pea protein aqueous solution Pea protein powder was dissolved in distilled water to prepare a 6% w / v pea protein stock solution. The specific steps included: first, adding distilled water to the dry powder to form a paste, then continuing to add distilled water and stirring with a magnetic stirrer until the powder was completely dissolved, and stirring magnetically at room temperature for 1 h, then hydrating in a refrigerator at 4–8°C for 8–12 h, raising the pH of the protein solution to 12 using 2 mol / L NaOH, stirring magnetically for 2 h, then sonicating with 37% amplitude for 20 min with 5 s on / off cycles, then gradually adjusting to pH 7 with 2 mol / L HCl solution, mixing for 0.5 h, and then centrifuging at 4°C and 2000g for 10 min, collecting the supernatant to obtain the pea protein solution, determining the protein content using a BCA assay kit, and then diluting the protein to the required concentration for later use. (2) Preparation of steviol glycoside aqueous solution Stevioside powder was dissolved in distilled water to prepare a 2% (w / v) steviol glycoside stock solution. The specific steps included: adding distilled water to the dry steviol glycoside powder, stirring magnetically until the steviol glycoside was completely dissolved, and adjusting the pH of the above solution to 7 using 2 mol / L NaOH solution. (3) Preparation of pea protein-stevioside binary complex A pea protein solution with pH adjusted to 7 was mixed with a steviol glycoside solution so that the final concentration of pea protein in the final mixture was 1%–5% (w / v) and the final concentration of steviol glycoside was 0.1%–1% (w / v). The mixture was stirred on a magnetic stirrer for at least 20 min to prepare a pea protein-stevioside binary complex. (4) Preparation of pea protein-stevioside nanoemulsion The pea protein-stevioside binary complex prepared in step (3) was mixed with soybean oil at an appropriate volume ratio. After homogenization for 2 min using a high-speed shear apparatus at a speed of 12,000 rpm, the resulting mixture was subjected to ultrasonic treatment for 20 min with an amplitude of 37% and an on / off cycle of 5 seconds to obtain the pea protein-stevioside nanoemulsion.
[0011] Beneficial effects: This invention constructs a pea protein-stevioside nanoemulsion, which effectively improves the instability issues of fat-free and sugar-free yogurt caused by the lack of fat and sugar, such as rough texture, whey separation, and flavor imbalance. This emulsion not only acts as a highly efficient fat mimic, embedding itself in the gel network to significantly improve texture, prevent whey separation, and impart a rich mouthfeel; simultaneously, steviol glycosides possess both natural sweetness and emulsifying function, providing sweetness while avoiding unpleasant aftertaste and masking the unique beany flavor of pea protein. Ultimately, a simple and clean process simultaneously achieves a dual improvement in both the texture and flavor of yogurt. Attached Figure Description
[0012] Figure 1 This is a schematic diagram of the particle size of different pea protein-stevia glycoside nanoemulsions in Example 1.
[0013] Figure 2 The pH change curves during the fermentation process of yogurt prepared based on pea protein-stevia glycoside nanoemulsion in Example 1 and the control group yogurt are shown.
[0014] Figure 3 This is a schematic diagram showing the particle size distribution of yogurt prepared based on pea protein-stevia glycoside nanoemulsion in Example 1 and the control group yogurt.
[0015] Figure 4 This is a schematic diagram showing the water-holding capacity of yogurt prepared based on pea protein-stevia glycoside nanoemulsion in Example 1 and the control group yogurt.
[0016] Figure 5 This is a schematic diagram showing the viscosity of yogurt prepared based on pea protein-stevia glycoside nanoemulsion in Example 1 and the control group yogurt.
[0017] Figure 6This is a schematic diagram showing the storage modulus of yogurt prepared based on pea protein-stevia glycoside nanoemulsion in Example 1 and the control group yogurt.
[0018] Figure 7 This is a schematic diagram showing the loss modulus of yogurt prepared based on pea protein-stevia glycoside nanoemulsion in Example 1 and the control group yogurt.
[0019] Figure 8 This is a schematic diagram showing the amount of volatile flavor compounds in the yogurt prepared based on pea protein-stevia glycoside nanoemulsion in Example 1 and the control group yogurt.
[0020] Figure 9 This is a schematic diagram showing the concentration of volatile flavor compounds in the yogurt prepared based on pea protein-stevia glycoside nanoemulsion in Example 1 and the control group yogurt.
[0021] Figure 10 The PCA diagram shows the amount of volatile flavor compounds in the yogurt prepared based on pea protein-stevia glycoside nanoemulsion in Example 1 and the control group yogurt.
[0022] Figure 11 This is a schematic diagram illustrating the sensory evaluation of yogurt prepared based on pea protein-stevia glycoside nanoemulsion and the control group yogurt in Example 1. Detailed Implementation
[0023] The present invention will be further illustrated below with reference to specific embodiments. It should be understood that the embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Therefore, any modifications, equivalent substitutions, improvements, etc., made without departing from the spirit and scope of the invention should be included within the protection scope of the invention. Furthermore, the appended claims are intended to cover all variations and modifications falling within the scope and boundaries of the appended claims, or equivalent forms of such scope and boundaries.
[0024] Example 1: This embodiment provides a method for preparing yogurt based on pea protein-stevioside nanoemulsion, the steps of which are as follows: (1) Preparation of pea protein aqueous solution A certain amount of distilled water was added to a certain amount of pea protein powder to form a paste. The remaining distilled water was then added, and the mixture was magnetically stirred at 650 rpm for 1 hour until the powder was completely dissolved, yielding a 5% (w / v) pea protein solution. This solution was then hydrated at 4°C for 12 hours. The pH of the protein solution was raised to 12 using 2 mol / L NaOH, and the mixture was magnetically stirred for 2 hours. Afterward, it was sonicated for 20 minutes with a 37% amplitude and 5-second on / off cycle. The pH was then gradually adjusted to 7 using 2 mol / L HCl solution, and the mixture was stirred for 0.5 hours. Finally, it was hydrated at 4°C. oCentrifuge at 2000 g for 10 min at C. Collect the supernatant and determine its protein content using a BCA assay kit.
[0025] (2) Preparation of steviol glycoside aqueous solution Add a certain amount of steviol glycoside powder to distilled water and stir magnetically until the steviol glycosides are completely dissolved to prepare a 2% (w / v) steviol glycoside aqueous solution. Adjust the pH of the above solution to 7 using 2 mol / L NaOH solution and set aside for later use.
[0026] (3) Preparation of pea protein-stevioside binary complex Pea protein solutions adjusted to pH 7 were mixed with steviol glycoside solutions, resulting in a final PPI concentration of 2% and STE concentrations of 0, 0.1, 0.2, 0.4, 0.6, and 0.8%.
[0027] (4) Preparation of pea protein-stevioside nanoemulsion The above composite solution and soybean oil were mixed at a volume ratio of 70:30. The mixture was homogenized for 2 minutes using a high-speed shear apparatus at a speed of 12,000 rpm. The resulting mixture was then subjected to ultrasonic treatment for 20 minutes with an amplitude of 37% and an on / off cycle of 5 seconds to obtain a fine emulsion.
[0028] (5) Preparation of yogurt based on pea protein-stevioside nanoemulsion Take a certain amount of skim milk powder and place it in a container. Add distilled water to prepare a 4% solution. Add the different pea protein-stevia glycoside nanoemulsions prepared above at a volume ratio of 1%. Stir magnetically for at least 20 minutes to mix evenly. Then place it in a water bath and heat at 83°C for 15 minutes. After pasteurization, the mixture was cooled to 42°C and 0.006% (w / v) of starter culture was added. The mixture was then magnetically stirred to ensure uniform mixing. The mixture was then transferred to a 43°C incubator for fermentation for 6 hours. Subsequently, the yogurt was transferred to a 4°C refrigerator and allowed to mature for 12 hours to obtain 2% pea protein emulsion yogurt (PY), 0.1% pea protein-stevioside emulsion yogurt (0.1% PSY), 0.2% pea protein-stevioside emulsion yogurt (0.2% PSY), 0.4% pea protein-stevioside emulsion yogurt (0.4% PSY), 0.6% pea protein-stevioside emulsion yogurt (0.6% PSY), and 0.8% pea protein-stevioside emulsion yogurt (0.8% PSY).
[0029] The difference in the preparation method of the control group yogurt (CY) was that the above nanoemulsion was replaced with the same volume of distilled water. The changes in pH, particle size and distribution, water-holding capacity, viscosity, rheological properties, microstructure, volatile flavor compounds, textural properties, color, and sensory evaluation were measured in both the experimental and control groups during fermentation. The results are as follows: L* a* b* W* CY 86.76 -2.07 1.48 86.65 PY 95.84 -2.2 7.05 91.61 0.1% PSY 96.13 -2.15 6.88 91.80 0.2% PSY 95.58 -2.19 6.07 91.89 0.4% PSY 97.29 -2.13 6.91 92.55 0.6% PSY 97.4 -1.99 6.81 92.63 0.8% PSY 97.84 -1.94 6.83 92.83 The results showed that adding pea protein-stevioside nanoemulsion did not affect yogurt fermentation. Figure 2 Furthermore, it improved the quality of fat-free and sugar-free yogurt. Compared to control yogurt, emulsion yogurt had smaller particle size, better water retention, superior texture and rheological properties, and a richer flavor, making it more acceptable to consumers. This is partly due to the fact that nanoemulsions can be embedded in the casein network as active filler particles, strengthening the gel matrix, increasing cross-linking density, and forming a finer microstructure; and partly due to the cross-linking of pea protein and casein.
[0030] Droplets can act as structural fillers or disruptors in yogurt networks; particle size affects the compactness and continuity of the gel, thus influencing its ability to mimic fat globules. However, as... Figure 1 As shown, although the particle size of the pea protein-stevia glycoside nanoemulsion gradually decreases with increasing steviol glycoside concentration, key quality indicators such as the microstructure, water retention, texture, and rheological properties of the yogurt gel network constructed from it do not show a simple linear improvement. Instead, these indicators reach a synergistic optimal value within a specific pea protein to steviol glycoside concentration ratio (5:1). Under this optimal ratio, the formed nanoemulsion can most effectively embed and modify the protein gel network of yogurt, not only significantly reducing the particle size of the yogurt but, more importantly, inducing the formation of a three-dimensional gel structure with high density, high viscosity, high rigidity, and excellent shear resistance. Figure 6 , Figure 7 When the concentration of steviol glycosides is below 0.4%, the resulting nanoemulsion has a larger particle size. Figure 3 This results in larger pores in the three-dimensional structure of the emulsion yogurt; when the concentration is higher than 0.4%, excessive steviol glycosides may spatially hinder the interaction between pea protein and casein matrix, disrupting the formation of a uniform three-dimensional network, ultimately leading to a weaker gel structure and poorer texture, just as... Figure 4 The lower water holding capacity and Figure 5 The viscosity was relatively poor. This finding suggests that a specific mass ratio is key to maximizing the emulsion's function as a highly efficient fat mimic and stabilizer, and its effect is far more than a simple additive of the functions of each component; rather, it produces a synergistic and enhancing "threshold effect."
[0031] Furthermore, unlike the case of using pea protein nanoemulsions alone, Figure 9 and 10 This indicates that the addition of emulsions increases the diversity and richness of volatile compounds in yogurt after fermentation. Low-fat, sugar-free yogurt based on pea protein-stevioside nanoemulsion produced a significant two-way flavor improvement effect: on the one hand, the system effectively suppressed the inherent beany taste of pea protein; on the other hand, it masked the bitter aftertaste and metallic aftertaste commonly found at high concentrations of steviol glycosides. This synergistic flavor improvement is not simply a matter of taste neutralization; we hypothesize that at the nanoscale, steviol glycoside molecules and pea protein form new complexes through intermolecular interactions (such as hydrogen bonds and hydrophobic interactions), thereby jointly reducing the exposure to undesirable flavor receptors from both physical and chemical perspectives. Ultimately, the resulting yogurt exhibits a pure, harmonious fermented milk flavor with a richer spectrum of volatile flavor compounds, resulting in a qualitative leap in overall sensory acceptance. Figure 11 ).
[0032] In summary, pea protein-stevioside emulsion can effectively optimize the gel structure and mechanical properties of fat-free and sugar-free yogurt, demonstrating great potential as a fat substitute in the development of high-quality dairy products and showing broad application prospects.
Claims
1. A method for preparing low-fat, sugar-free yogurt based on pea protein-stevia glycoside nanoemulsion, comprising the following steps: 1) Place the skim milk powder in a container, add distilled water to prepare a 1% to 5% solution, add pea protein-stevia glycoside nanoemulsion, and stir magnetically for at least 20 minutes to mix it evenly; 2) Place the solution in a water bath and heat at 80-85°C for 15 minutes. After pasteurization, cool to 40-43°C and add 0.004%-0.008% w / v of starter culture. Stir magnetically to mix evenly. 3) Transfer the above mixture to a constant temperature incubator at 42-45℃ for fermentation for 4-8 hours. Then transfer the yogurt to a refrigerator at 4-8℃ and allow it to mature for 10-24 hours to obtain yogurt containing pea protein-stevia glycoside nanoemulsion.
2. The method for preparing low-fat, sugar-free yogurt based on pea protein-stevia glycoside nanoemulsion according to claim 1, characterized in that, The proportion of pea protein-stevia glycoside nanoemulsion added in step 1) is 0.5% to 2% of the solution volume.
3. The method for preparing low-fat, sugar-free yogurt based on pea protein-stevia glycoside nanoemulsion according to claim 1, characterized in that, The components of the pea protein-stevioside nanoemulsion mentioned in step 1) include: pea protein at a mass / volume concentration of 1% to 5%, steviol glycoside at a mass / volume concentration of 0.1% to 1%, and soybean oil at a mass / volume concentration of 10% to 30% w / v, with the balance being distilled water.
4. The method for preparing low-fat, sugar-free yogurt based on pea protein-stevia glycoside nanoemulsion according to claim 1, characterized in that, The pea protein-stevioside nanoemulsion mentioned in step 1) is prepared according to the following method: (1) Preparation of pea protein aqueous solution Pea protein powder was dissolved in distilled water to prepare a 6% w / v pea protein stock solution. The specific steps included: first, adding distilled water to the dry powder to form a paste, then continuing to add distilled water and stirring with a magnetic stirrer until the powder was completely dissolved, and stirring magnetically at room temperature for 1 h, then hydrating in a refrigerator at 4–8°C for 8–12 h, raising the pH of the protein solution to 12 using 2 mol / L NaOH, stirring magnetically for 2 h, then sonicating with 37% amplitude for 20 min with 5 s on / off cycles, then gradually adjusting to pH 7 with 2 mol / L HCl solution, mixing for 0.5 h, and then centrifuging at 4°C and 2000g for 10 min, collecting the supernatant to obtain the pea protein solution, determining the protein content using a BCA assay kit, and then diluting the protein to the required concentration for later use. (2) Preparation of steviol glycoside aqueous solution Stevioside powder was dissolved in distilled water to prepare a 2% (w / v) steviol glycoside stock solution. The specific steps included: adding distilled water to the dry steviol glycoside powder, stirring magnetically until the steviol glycoside was completely dissolved, and adjusting the pH of the above solution to 7 using 2 mol / L NaOH solution for later use. (3) Preparation of pea protein-stevioside binary complex A pea protein solution with pH adjusted to 7 was mixed with a steviol glycoside solution so that the final concentration of pea protein in the final mixture was 1%–5% (w / v) and the final concentration of steviol glycoside was 0.1%–1% (w / v). The mixture was stirred on a magnetic stirrer for at least 20 min to prepare a pea protein-stevioside binary complex. (4) Preparation of pea protein-stevioside nanoemulsion The pea protein-stevioside binary complex prepared in step (3) was mixed with soybean oil at an appropriate volume ratio. After homogenization for 2 min using a high-speed shear apparatus at a speed of 12,000 rpm, the resulting mixture was subjected to ultrasonic treatment for 20 min with an amplitude of 37% and an on / off cycle of 5 seconds to obtain the pea protein-stevioside nanoemulsion.