High-protein high-dietary-fiber flavored yoghurt and preparation method thereof

Abstract

The invention belongs to the technical field of dairy product processing, and particularly relates to high-protein high-dietary-fiber flavored yoghourt and a preparation method thereof. The yoghourt is prepared from the following raw materials: a protein system, a fiber system, a sweet system and a flavor system, wherein the protein system is composed of micelle casein and whey protein isolate according to a mass ratio of 3: (1-3); the fiber system is composed of short-chain inulin and oat beta-glucan according to the mass ratio of 2: (1-3); the sweet system consists of erythritol and stevioside in a mass ratio of 10: (1-5); the flavor system is composed of a natural vanilla extract and a fermented frankincense base material according to a mass ratio of 2: (1-2). The fermented milk product prepared by the method not only inherits all nutritional advantages and clean label characteristics of the original flavor, but also realizes a major breakthrough in sensory experience through precise application of natural flavor and a cold mixing process. The authenticity of the natural flavor and the excellent peculiar smell masking effect are fully verified by sensory evaluation.

Description

Technical Field

[0001] This invention belongs to the field of dairy processing technology, and specifically relates to a high-protein, high-dietary-fiber flavored yogurt and its preparation method. Background Technology

[0002] With the increasing trend towards healthy eating, the market demand for high-protein and high-fiber yogurt has grown significantly. Current technologies mainly rely on exogenous protein additions (such as WPC / WPI) and fiber supplementation (inulin, polydextrose), but these generally suffer from the following problems: ① Texture defects caused by protein addition: Excessive protein powder can cause a gritty texture, astringency, and whey separation. ② Limitations of fiber addition: Inulin and other fibers are prone to producing off-flavors at high concentrations and have poor synergy with protein. ③ Insufficient process compatibility: Traditional pre-fermentation addition processes struggle to simultaneously optimize protein solubility and fiber stability. ④ Unmet clean labeling requirements: Most products rely on colloids and stabilizers to mask defects.

[0003] Furthermore, current technologies have not solved the problems of stability and taste balance in the protein-fiber-fat three-phase system. In particular, there is a lack of solutions for achieving efficient utilization of natural components through process innovation. Summary of the Invention

[0004] The purpose of this invention is to provide a high-protein, high-fiber flavored yogurt and its preparation method, which can achieve a clean label, balanced nutrition and taste in innovative dairy products through membrane technology integration, dynamic fermentation control and multi-stage texture recombination technology.

[0005] Therefore, the present invention provides the following technical solution.

[0006] One aspect of the present invention provides a high-protein, high-fiber flavored yogurt, the raw material composition of which includes: a protein system, a fiber system, a sweetener system, and a flavor system; wherein, the protein system is composed of micellar casein and whey protein isolate in a mass ratio of 3:(1-3); the fiber system is composed of short-chain inulin and oat β-glucan in a mass ratio of 2:(1-3); the sweetener system is composed of erythritol and steviol glycosides in a mass ratio of 10:(1-5); and the flavor system is composed of natural vanilla extract and fermented frankincense base in a mass ratio of 2:(1-2).

[0007] In a preferred embodiment of the invention, the short-chain inulin has a polymer density (DP) of <10. Inulin with a low degree of polymerization has better solubility and a milder sweetness, and can more effectively improve the texture of yogurt without creating a gritty feel.

[0008] In a preferred embodiment of the present invention, the raw material composition of the yogurt further includes: a starter culture, wherein the starter culture is selected from one or more of Streptococcus thermophilus, Lactobacillus delbrueckii subsp. bulgaricus, and Bifidobacterium lactis.

[0009] In a preferred embodiment of the present invention, the raw material composition of the yogurt, by weight, includes: 85-95 parts of membrane-integrated pretreated milk base, 5-10 parts of protein system, 4-6 parts of fiber system, 3-5 parts of sweetening system, 0.5-0.7 parts of flavor system, and 0.05-0.09 parts of starter culture. The membrane-integrated pretreated milk base is a milk base rich in protein and partially lactose-free obtained by membrane-integrated pretreatment of raw milk consisting of microfiltration, ultrafiltration, and nanofiltration.

[0010] In a preferred embodiment of the present invention, the fermenting agent is composed of Streptococcus thermophilus, Lactobacillus delbrueckii subsp. bulgaricus, and Bifidobacterium lactis in a mass ratio of 2:1:5. This specific ratio of compound microorganisms can work synergistically to impart a milder aroma and a higher number of viable probiotics to the product while ensuring good acid-producing characteristics.

[0011] Another aspect of the present invention provides a method for preparing high-protein, high-dietary-fiber flavored yogurt, the method comprising the following steps: S1: Raw milk is pretreated with membrane integration to obtain membrane-integrated pretreated milk base material; S2: According to the weight ratio, add the membrane integration pretreatment milk base, protein system, fiber system and sweetener system into the mixing tank in sequence and stir to mix well to obtain the mixture; S3: The mixture is homogenized in multiple stages and then sterilized to obtain fermentation raw material; S4: Add a fermenting agent to the fermentation raw materials to carry out fermentation and obtain a fermentation liquid; S5: Demulsify and cool the fermentation liquid, then add the flavoring system, stir and mix well, and finally fill it under aseptic conditions to obtain the flavored yogurt product.

[0012] This invention employs a "cold-mixing process," meaning the flavor system is added only after fermentation is complete and the mixture has cooled. This process minimizes the volatilization or denaturation of heat-sensitive flavor compounds in natural vanilla extracts during sterilization and fermentation, thus preserving the authenticity and complexity of the flavor. Simultaneously, low-temperature mixing helps maintain the integrity of the fermented gel structure, preventing textural damage and whey separation caused by high-temperature stirring.

[0013] In a preferred embodiment of the present invention, in step S1, the membrane integration pretreatment process is as follows: first, ceramic microfiltration membrane filtration is used, then ultrafiltration membrane filtration is used, and finally nanofiltration membrane filtration is used. This three-stage membrane integration process can sequentially achieve cold sterilization, protein concentration, and lactose adjustment, which is key to obtaining high-quality, high-protein substrates.

[0014] In a preferred embodiment of the present invention, the filtration conditions of the ceramic microfiltration membrane are: pore size 1.4 μm and temperature 4 °C.

[0015] In a preferred embodiment of the present invention, the ultrafiltration membrane filtration conditions are: molecular weight cutoff of 10 kDa, concentration ratio of 4 times, transmembrane pressure of 0.6 MPa, and temperature of 50°C.

[0016] In a preferred embodiment of the present invention, the nanofiltration membrane filtration conditions are: molecular weight cutoff of 200 Da.

[0017] In a preferred embodiment of the present invention, in step S2, the stirring and mixing conditions are: temperature 40-45°C, time 25-35 min.

[0018] In a preferred embodiment of the present invention, step S3, the homogenization includes primary homogenization and secondary homogenization. This multi-stage homogenization process helps to form a finer and more stable protein-cellulose mixture system.

[0019] In a preferred embodiment of the present invention, the primary homogenization conditions are: pressure 20-30 MPa and temperature 40-50 °C.

[0020] In a preferred embodiment of the present invention, the secondary homogenization conditions are: pressure 4-6 MPa, temperature 20-25°C.

[0021] In a preferred embodiment of the present invention, the sterilization is pasteurization, and the sterilization conditions are: temperature 95°C, time 300s.

[0022] In a preferred embodiment of the present invention, in step S4, the fermentation conditions are as follows: first, fermentation is carried out at 42°C until the pH reaches 5.2, and then the temperature is lowered to 37°C in a water bath to continue fermentation until the pH reaches 4.6. This two-stage fermentation process is beneficial to the growth and metabolism of different microbial strains, thereby optimizing the flavor and texture of the product.

[0023] In a preferred embodiment of the present invention, in step S5, the demulsification conditions are: temperature 37-40℃ and rotation speed 20-30rpm.

[0024] In a preferred embodiment of the present invention, in step S5, the stirring and mixing conditions are: temperature 20-25℃, rotation speed 20-30rpm, and time 10-15min.

[0025] By employing the above technical solution, the present invention has at least the following advantages: The vanilla-flavored fermented milk product prepared by this invention not only inherits all the nutritional advantages and clean label characteristics of the original flavor, but also achieves a major breakthrough in sensory experience through the precise application of natural flavor and cold-mixing process. Its authentic natural flavor and excellent odor masking effect have been fully verified by sensory evaluation, comprehensively surpassing commercially available products that use artificial flavors and added sugars.

[0026] This invention utilizes a membrane integration process to improve protein utilization: basic protein reaches 5.5%, and the amount of exogenous protein added is reduced by 40%. By adding β-glucan to form a gel network with micellar casein, fiber compatibility is enhanced, and water-holding capacity is increased by 25%. The flavored yogurt of this invention contains zero added colloids / stabilizers, with a whey separation rate of only 2.3% and a viscosity of 4500±200 cP (compared to competitors ≥6000 cP), exhibiting excellent sensory flavor.

[0027] The above description is merely an overview of the technical solution of the present invention. In order to better understand the technical means of the present invention and to implement it in accordance with the contents of the specification, the preferred embodiments of the present invention are described in detail below. Detailed Implementation

[0028] To make the technical means, creative features, achieved objectives, and effects of this invention readily understandable, the technical solutions in the embodiments of this invention will be clearly and completely described below in conjunction with the embodiments of this invention. Obviously, the described embodiments are merely some embodiments of this invention, and not all embodiments. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0029] Table 1 below shows an analysis of existing technologies for achieving high protein and high fiber content. As shown in Table 1, several limitations still exist in the existing technologies.

[0030] Table 1. Analysis of existing technologies for achieving high protein and high fiber content. ; Therefore, this invention provides a flavored yogurt ingredient composed of a protein system, a fiber system, a sweetening system, and a flavor system. In the sweetening system, because the vanilla flavor requires stronger sweetness to balance its rich flavor, the amount of erythritol is increased to 4.8%, and the ratio of steviol glycosides is adjusted to 240:1 to ensure a full sweetness without any aftertaste of bitterness. Natural vanilla pod extract is the core of the flavor system. Synthetic flavorings such as vanillin and ethyl vanillin are rejected; instead, a natural extract containing visible black vanilla seed particles is selected, which is a key visual and flavor indicator supporting the claims of "naturally sourced flavor and high-end quality." To reduce the interference of fermentation acid production on the main vanilla flavor, the total amount of starter culture is slightly reduced to ensure an optimal balance between final acidity, sweetness, and flavor.

[0031] The following embodiments involve and mention: 1. Materials The raw milk, micellar casein, whey protein isolate, short-chain inulin (DP < 10), oat β-glucan, erythritol, steviol glycosides, and natural vanilla extract (containing vanilla seeds) are all commercially available food-grade raw materials.

[0032] Fermented milk flavor enhancers are commercially available natural milk flavor enhancers produced through microbial fermentation or enzymatic hydrolysis. Their main components are lactic acid, fatty acids, and carbonyl compounds, used to enhance the milky aroma and rich, fermented milk flavor of products. Typical commercially available products include, but are not limited to, natural milk flavor enhancers from brands such as Givaudan and Firmenich.

[0033] The starter cultures (Streptococcus thermophilus, Lactobacillus delbrueckii subsp. bulgaricus, and Bifidobacterium lactis) are all commercially available direct-inoculation starter cultures.

[0034] 2. Instruments Ceramic microfiltration membrane equipment, ultrafiltration membrane equipment, nanofiltration membrane equipment, batching tanks, two-stage homogenizers, plate heat exchangers, fermentation tanks, aseptic filling machines, etc. are all commercially available products.

[0035] Example 1: A high-protein, high-fiber flavored yogurt, with a total weight of 100 wt%, its raw material composition and content are shown in Table 2: Table 2. Raw material composition and content of fermented milk ; The method for preparing the above-mentioned flavored yogurt includes the following steps: Step 1: Filter the raw milk through a ceramic microfiltration membrane system (membrane pore size 1.4μm, temperature 4℃) for cold sterilization, retaining active ingredients to obtain the primary filtrate. Filter the primary filtrate through an ultrafiltration membrane system (molecular weight cutoff 10kDa, concentration ratio 4X, transmembrane pressure 0.6MPa, temperature 50℃) to concentrate the protein to the target content, obtaining the secondary filtrate. Filter the secondary filtrate through a nanofiltration membrane system (molecular weight cutoff 200Da) to remove some lactose, obtaining the membrane-integrated pretreated milk base.

[0036] Step 2: According to the weight ratio, add the obtained membrane integrated pretreated milk base, micelle casein, whey protein isolate, short-chain inulin, oat β-glucan, erythritol and steviol glycosides into the mixing tank, and stir at 45°C for 30 minutes to completely hydrate and dissolve the dry materials such as fiber and protein to obtain the mixture.

[0037] Step 3: Place the obtained mixture in a two-stage homogenizer for homogenization (first-stage homogenization conditions: pressure 25MPa, temperature 45℃; second-stage homogenization conditions: pressure 5MPa, temperature 20℃). Then, place the liquid in a plate heat exchanger and sterilize it at 95℃ for 300s to kill miscellaneous bacteria, creating a pure environment for the fermentation agent and obtaining the fermentation raw material.

[0038] Step 4: Add Streptococcus thermophilus, Lactobacillus delbrueckii subsp. bulgaricus, and Bifidobacterium lactis to the obtained fermentation raw materials for fermentation. First, ferment at 42℃ until pH=5.2, then cool in a water bath to 37℃ and continue fermentation until pH=4.6 to obtain the fermentation broth.

[0039] Step 5: Demulsify the obtained fermentation liquid at 20 rpm, then cool it to 20°C, then add natural vanilla pod extract and fermented frankincense base, stir and mix at 20°C and 25 rpm for 10 min, and finally fill it in an aseptic environment to obtain the flavored yogurt product.

[0040] Example 2: The raw material composition of Example 2 is basically the same as that of Example 1, except that the ratio of each system is adjusted. Specifically, the amount of protein system (micelle casein: whey protein isolate = 3:2) added is 7.5 parts; the amount of fiber system (short-chain inulin: oat β-glucan = 2:2) added is 5 parts; the amount of sweetness system (erythritol: steviol glycosides = 10:3) added is 4 parts; the amount of flavor system (natural vanilla extract: fermented frankincense base = 2:1.5) added is 0.6 parts; and the amount of fermentation agent (Streptococcus thermophilus: Lactobacillus delbrueckii subsp. bulgaricus: Bifidobacterium lactis = 2:1:5) added is 0.07 parts.

[0041] The preparation method is the same as in Example 1.

[0042] Example 3: The raw material composition of Example 3 is basically the same as that of Example 1, except that the ratios of each system are adjusted. Specifically, the protein system (micelle casein: whey protein isolate = 3:3) is added in amounts of 10 parts; the fiber system (short-chain inulin: oat β-glucan = 2:3) is added in amounts of 6 parts; the sweetness system (erythritol: steviol glycosides = 10:5) is added in amounts of 5 parts; the flavor system (natural vanilla extract: fermented frankincense base = 2:2) is added in amounts of 0.7 parts; and the fermentation agent (Streptococcus thermophilus: Lactobacillus delbrueckii subsp. bulgaricus: Bifidobacterium lactis = 2:1:5) is added in amounts of 0.05 parts. The preparation method is the same as that of Example 1.

[0043] Example 4: The raw material composition of Example 4 is basically the same as that of Example 1, except that the whey protein isolate is replaced with polymerized whey protein. Specifically, the preparation process of the polymerized whey protein is as follows: the whey protein isolate (same as in Example 1) is prepared into a 10% (w / w) solution, the pH is adjusted to 7.5, and heat-treated at 85°C for 30 min to induce protein polymerization. Then, it is rapidly cooled to 25°C to obtain the polymerized whey protein solution. Size exclusion chromatography (SEC-HPLC) was used to detect its degree of polymerization ≥70%; laser particle size analyzer was used to detect its particle size in the range of 1-10 μm.

[0044] The composition of the remaining raw materials is the same as in Example 1, namely: 82.5 parts of membrane-integrated pretreated milk base, 5 parts of micellar casein, 2 parts of polymerized whey protein (replacing the original whey protein isolate), 3.5 parts of short-chain inulin, 1.5 parts of oat β-glucan, 4.8 parts of erythritol, 0.02 parts of steviol glycosides, 0.4 parts of natural vanilla pod extract, 0.2 parts of fermented frankincense base, and 0.08 parts of starter culture (Streptococcus thermophilus: Lactobacillus delbrueckii subsp. bulgaricus: Bifidobacterium lactis = 2:1:5).

[0045] The preparation method is the same as in Example 1.

[0046] Comparative Example 1: The difference between Comparative Example 1 and Example 1 is that the flavor system is not added in step five, but is added together with other ingredients in step two. The remaining steps are the same as in Example 1.

[0047] Comparative Example 2: Comparative Example 2 is a commercially available brand of high-protein vanilla-flavored yogurt.

[0048] Experiment 1: Nutritional Analysis of Flavored Yogurt The nutritional components of the flavored yogurts prepared in Examples 1-4 and Comparative Examples 1-2 were tested against those of commercially available yogurts. The testing methods are shown in Table 3, and the results are shown in Table 4.

[0049] Table 3. Methods for detecting the nutritional components of yogurt ; Table 4. Nutritional composition test results of yogurt ; As shown in Table 4, compared to Comparative Examples 1-2, the yogurt prepared in Examples 1-3 of this invention is superior to the commercially available comparative examples in terms of protein and dietary fiber content, and has a lower whey separation rate, achieving a clean label with zero added sugar and zero synthetic flavorings. Compared to Example 1, Example 4 uses polymerized whey protein instead of whey protein isolate. The polymerized whey protein enhances the gel network, reduces whey separation, and increases protein content.

[0050] Experiment 2: Sensory Evaluation Results of Flavored Yogurt Twenty professionally trained group members were invited to conduct sensory evaluations (out of 10) on the yogurts prepared in Examples 1-4 and Comparative Examples 1-2. The results are shown in Table 5.

[0051] Table 5 Sensory rating results of flavored yogurt ; As shown in Table 5, Examples 1-3 of this invention significantly improved the authenticity of the vanilla flavor and the odor masking effect through the cold-mixing process (different from Comparative Example 1), and the overall acceptance rate comprehensively surpassed that of commercially available competing products (Comparative Example 2). Example 4 outperformed Examples 1-3 in all sensory scores, especially in smoothness (8.8) and overall acceptance rate (8.7). This indicates that the enhanced gel network formed by polymerized whey protein not only improved textural stability but also enhanced the smoothness of the product's mouthfeel and the flavor release effect. The vanilla-flavored product of this invention not only inherits all the nutritional advantages and clean label characteristics of the original flavor, but also achieves a major breakthrough in sensory experience through the precise application of natural flavor and the cold-mixing process. Its natural flavor authenticity and excellent odor masking effect have been fully verified by sensory evaluation, comprehensively surpassing commercially available competing products that use flavorings and added sugars.

[0052] In summary, this invention obtains high-quality milk base material through membrane-integrated pretreatment technology, achieves nutritional balance through the synergistic design of protein, fiber, sweetness, and flavor systems, protects natural flavor through cold-mixing, and further enhances the product's textural stability, nutritional quality, and probiotic survival rate by introducing polymerized whey protein. The vanilla-flavored product of this invention not only inherits all the nutritional advantages and clean label characteristics of the original flavor, but also achieves a significant breakthrough in sensory experience. Its authentic natural flavor and excellent odor masking effect have been fully verified by sensory evaluation, comprehensively surpassing commercially available products that use artificial flavors and added sugars.

[0053] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications or alterations to the methods and techniques disclosed above without departing from the scope of the present invention to create equivalent embodiments. Any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.

Claims

1. A high-protein, high-dietary-fiber flavored yogurt, characterized in that, The raw material composition of the yogurt includes: a protein system, a fiber system, a sweetening system, and a flavor system; wherein, The protein system is composed of micellar casein and whey protein isolates in a mass ratio of 3:(1-3); The fiber system is composed of short-chain inulin and oat β-glucan in a mass ratio of 2:(1-3); The sweetness system is composed of erythritol and steviol glycosides in a mass ratio of 10:(1-5); The flavor system is composed of natural vanilla extract and fermented frankincense base in a mass ratio of 2:(1-2).

2. The high-protein, high-fiber flavored yogurt according to claim 1, characterized in that, The DP of the short-chain inulin is <10.

3. The high-protein, high-dietary-fiber flavored yogurt according to claim 1, characterized in that, The raw material composition of the yogurt also includes: a starter culture, which is selected from one or more of Streptococcus thermophilus, Lactobacillus delbrueckii subsp. bulgaricus, and Bifidobacterium lactis.

4. The high-protein, high-fiber flavored yogurt according to any one of claims 1-3, characterized in that, The raw material composition of the yogurt, by weight, includes: 85-95 parts of membrane-integrated pretreated milk base, 5-10 parts of protein system, 4-6 parts of fiber system, 3-5 parts of sweetness system, 0.5-0.7 parts of flavor system, and 0.05-0.09 parts of starter culture. The membrane-integrated pretreated milk base material is a milk base material rich in protein and partially lactose removed, obtained by pretreating raw milk through a membrane-integrated pretreatment consisting of microfiltration, ultrafiltration, and nanofiltration.

5. The high-protein, high-dietary-fiber flavored yogurt according to claim 4, characterized in that, The starter culture is composed of Streptococcus thermophilus, Lactobacillus delbrueckii subsp. bulgaricus, and Bifidobacterium lactis in a mass ratio of 2:1:

5.

6. The method for preparing high-protein, high-dietary-fiber flavored yogurt according to any one of claims 1-5, characterized in that, The method includes the following steps: S1: Raw milk is pretreated with membrane integration to obtain membrane-integrated pretreated milk base material; S2: According to the weight ratio, add the membrane integration pretreatment milk base, protein system, fiber system and sweetener system into the mixing tank in sequence and stir to mix well to obtain the mixture; S3: The mixture is homogenized in multiple stages and then sterilized to obtain fermentation raw material; S4: Add a fermenting agent to the fermentation raw materials to carry out fermentation and obtain a fermentation liquid; S5: Demulsify and cool the fermentation liquid, then add the flavoring system, stir and mix well, and finally fill it under aseptic conditions to obtain the flavored yogurt product.

7. The preparation method according to claim 6, characterized in that, In step S1, the membrane integration pretreatment process is as follows: first, ceramic microfiltration membrane filtration is used, then ultrafiltration membrane filtration is used, and finally nanofiltration membrane filtration is used. The ceramic microfiltration membrane was used under the following filtration conditions: pore size 1.4 μm, temperature 4 °C. The ultrafiltration membrane filtration conditions are: molecular weight cutoff of 10 kDa, concentration ratio of 4 times, transmembrane pressure of 0.6 MPa, and temperature of 50°C. The nanofiltration membrane filtration conditions are: molecular weight cutoff of 200 Da; In step S2, the stirring and mixing conditions are: temperature 40-45℃, time 25-35min.

8. The preparation method according to claim 6, characterized in that, In step S3, the homogenization includes primary homogenization and secondary homogenization; The primary homogenization conditions are: pressure 20-30 MPa, temperature 40-50℃; The secondary homogenization conditions are: pressure 4-6 MPa, temperature 20-25℃; The sterilization is pasteurization, and the sterilization conditions are: temperature 95℃, time 300s.

9. The preparation method according to claim 6, characterized in that, In step S4, the fermentation conditions are as follows: first, ferment at 42°C until the pH is 5.2, then cool down in a water bath to 37°C and continue fermentation until the pH is 4.

6.

10. The preparation method according to claim 6, characterized in that, In step S5, the demulsification conditions are: temperature 37-40℃, rotation speed 20-30 rpm; The mixing conditions are: temperature 20-25℃, rotation speed 20-30rpm, and time 10-15min.