A low-fat yogurt stabilizer, low-fat yogurt and its preparation method

Abstract

This invention belongs to the field of dairy product technology, specifically relating to a low-fat yogurt stabilizer, low-fat yogurt, and its preparation method. The low-fat yogurt stabilizer comprises starch, pectin, orange fiber, and inulin, with a weight ratio of (50-100):(1-3):(20-30):(200-300). This low-fat yogurt stabilizer contains only one type of colloid, with a low colloid content, resulting in low cost. Furthermore, the low-fat yogurt prepared based on this stabilizer exhibits good stability, a rich fat flavor, and a pleasant taste; it also contains abundant dietary fiber, enriching the functions of yogurt.

Description

Technical Field

[0001] This invention belongs to the field of dairy product technology, specifically relating to a low-fat yogurt stabilizer, low-fat yogurt, and its preparation method. Background Technology

[0002] Yogurt is a popular beverage nowadays. With the increasing emphasis on healthy eating in society, consumers have raised requirements for the fat content of yogurt. Low-fat yogurt (the national standard defines low-fat yogurt as yogurt with a fat content of ≤1.5g / 100ml) has become a popular yogurt drink among consumers.

[0003] However, low-fat yogurt, due to its lower fat content, often suffers from a thin texture and poor whey separation, leading to instability. Current methods for stabilizing low-fat yogurt involve the compounding of various colloids, starches, and emulsifiers. Commonly used colloids include gelatin, gellan gum, agar, xanthan gum, carrageenan, and sodium carboxymethyl cellulose, with two, three, or even four types used simultaneously. For example, patent CN103081995A discloses a compound stabilizer, fermented yogurt containing it, and a method for preparing the fermented yogurt. The provided compound stabilizer contains esterified modified starch, pectin, sodium alginate, agar, xanthan gum, and gelatin—five colloid components alone. These colloid raw materials are expensive. Furthermore, with more than two colloids, consumers may perceive the product's viscosity as a result of colloid accumulation, rather than genuine ingredients, believing they are consuming only thickeners. This is clearly disadvantageous for consumers who are increasingly concerned about product labels. In addition, existing technologies struggle to address the lack of fat flavor in nonfat yogurt. While most of this can be solved by adding milk flavoring, issues remain, such as incomplete flavor integration, flavoring that tends to float on the surface, and an uncoordinated taste.

[0004] Therefore, it is necessary to develop a low-fat yogurt stabilizer that contains fewer types of gums, can be used to prepare low-fat yogurt, produces low-fat yogurt with good stability and taste, and can provide fat flavor directly without adding flavorings. Summary of the Invention

[0005] To address the above problems, one of the objectives of this invention is to provide a low-fat yogurt stabilizer that improves the stability and taste of low-fat yogurt through the combined action of starch, pectin, orange fiber, and inulin. The resulting low-fat yogurt has a rich taste, good texture, good stability, and a full fat flavor.

[0006] To achieve the above objectives, the present invention can adopt the following technical solutions:

[0007] The present invention provides a low-fat yogurt stabilizer comprising: starch, pectin, orange fiber and inulin, wherein the weight ratio of starch, pectin, orange fiber and inulin is (50~100):(1~3):(20~30):(200~300).

[0008] Preferably, the weight ratio of the starch, pectin, orange fiber and inulin is 100:2:30:300.

[0009] Preferably, the starch mentioned above is starch D1.

[0010] Another aspect of the present invention provides a low-fat yogurt, the raw materials of which include a low-fat yogurt stabilizer and a low-fat yogurt base; the weight of the low-fat yogurt stabilizer accounts for 4% to 5% of the weight of the raw materials.

[0011] Preferably, the low-fat yogurt base material includes sweetener, whole milk powder, skim milk powder, starter culture, and water; per 1000 parts by weight of raw materials, it includes: 50 to 60 parts by weight of sweetener, 40 to 60 parts by weight of whole milk powder, 40 to 60 parts by weight of skim milk powder, 40 to 50 parts by weight of low-fat yogurt stabilizer, 0.02 to 0.04 parts by weight of starter culture, and the balance being water.

[0012] Preferably, the above-mentioned fermenting agent is a compound fermenting agent of 161 fermenting agent and C975 fermenting agent.

[0013] Preferably, the weight ratio of the above-mentioned 161 fermentation agent and C975 fermentation agent is 1:1.

[0014] Preferably, the sweeteners include one or more of white sugar, maltitol, xylitol, erythritol, or polydextrose.

[0015] In another aspect, the present invention provides a method for preparing the above-mentioned low-fat yogurt, characterized in that it includes: mixing low-fat yogurt base material and low-fat yogurt stabilizer evenly to obtain a mixture; homogenizing the mixture, sterilizing, inoculating with a starter culture, breaking the emulsion and cooling, and then refrigerating at low temperature to obtain low-fat yogurt.

[0016] The beneficial effects of this invention include at least the following:

[0017] (1) The low-fat yogurt stabilizer provided by the present invention contains only one type of colloid, and the colloid content is low, resulting in low cost;

[0018] (2) The low-fat yogurt prepared based on the low-fat yogurt stabilizer provided by the present invention has good stability, sufficient fat flavor, and good taste;

[0019] (3) The low-fat yogurt prepared based on the low-fat yogurt stabilizer provided by the present invention contains rich dietary fiber, which enriches the function of yogurt. Attached Figure Description

[0020] Figure 1 A bar chart showing the viscosity of samples prepared from different types of starch in Example 1;

[0021] Figure 2 This is a bar chart showing the texture of samples prepared from different types of starch in Example 1;

[0022] Figure 3 This is a bar chart showing the cohesive strength of samples prepared from different types of starch in Example 1;

[0023] Figure 4 This is a bar chart showing the viscosity of samples prepared with different amounts of starch D1 in Example 2;

[0024] Figure 5 The bar chart shows the texture of samples prepared with different amounts of starch D1 in Example 2.

[0025] Figure 6 This is a bar chart showing the cohesive strength of samples prepared with different amounts of starch D1 in Example 2;

[0026] Figure 7 A bar chart showing the viscosity of the sample prepared in Example 3;

[0027] Figure 8 This is a bar chart showing the texture of the sample prepared in Example 3;

[0028] Figure 9 This is a bar chart showing the cohesive strength of the samples prepared in Example 3;

[0029] Figure 10 This is a bar chart showing the water-holding capacity of the samples prepared in Example 3;

[0030] Figure 11 A bar chart showing the viscosity of the sample prepared in Example 4;

[0031] Figure 12 This is a bar chart showing the texture of the sample prepared in Example 4;

[0032] Figure 13 This is a bar chart showing the cohesive strength of the samples prepared in Example 4;

[0033] Figure 14 This is a bar chart showing the water-holding capacity of the sample prepared in Example 4;

[0034] Figure 15 This is a bar chart showing the clarification index of the samples prepared in Example 4;

[0035] Figure 16 A bar chart showing the viscosity of the sample prepared in Example 5;

[0036] Figure 17 This is a bar chart showing the texture of the sample prepared in Example 5;

[0037] Figure 18 This is a bar chart showing the cohesive strength of the samples prepared in Example 5;

[0038] Figure 19 This is a bar chart showing the water-holding capacity of the sample prepared in Example 5;

[0039] Figure 20 A bar chart showing the clarification index of the samples prepared in Example 5;

[0040] Figure 21 A bar chart showing the viscosity of the sample prepared in Example 6;

[0041] Figure 22 A bar chart showing the texture of the sample prepared in Example 6;

[0042] Figure 23 This is a bar chart showing the cohesive strength of the samples prepared in Example 6;

[0043] Figure 24 This is a bar chart showing the water-holding capacity of the sample prepared in Example 6;

[0044] Figure 25 A bar chart showing the clarification index of the samples prepared in Example 6;

[0045] Figure 26 A bar chart showing the clarification index of the samples prepared in Example 7;

[0046] Figure 27 A bar chart showing the viscosity of the sample prepared in Example 7;

[0047] Figure 28 A bar chart showing the texture, cohesiveness, and water-holding capacity of the sample prepared in Example 7;

[0048] In the image, *: p <0.05, **: p <0.01, ***: p <0.001, ****: p <0.0001. Detailed Implementation

[0049] The embodiments described are provided to better illustrate the present invention, but are not intended to limit the scope of the invention to the embodiments described. Therefore, non-essential improvements and adjustments made to the embodiments by those skilled in the art based on the above description are still within the scope of protection of the present invention.

[0050] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit this disclosure. Singular expressions include plural expressions unless they have a distinct meaning in the context. As used herein, it should be understood that terms such as “comprising,” “having,” “including,” are intended to indicate the presence of a feature, number, operation, material, or combination thereof. The terminology of the invention is disclosed in the specification and is not intended to exclude the possibility that one or more other features, numbers, operations, materials, or combinations thereof may be present or added. As used herein, “ / ” may be interpreted as “and” or “or,” depending on the context.

[0051] In this invention, the term "low-fat yogurt" refers to yogurt with a protein content ≥2.5g / 100ml and a fat content ≤1.5g / 100ml; the term "starch D1" specifically refers to T0220 starch from Hangzhou Prostar Starch Co., Ltd.; the term "161 starter culture" is composed of Streptococcus thermophilus, Lactobacillus delbrueckii subsp. bulgaricus, and Lactobacillus delbrueckii subsp. lactis; and "c975 starter culture" is composed of Streptococcus thermophilus and Lactobacillus delbrueckii subsp. bulgaricus.

[0052] This invention provides a low-fat yogurt stabilizer, comprising: starch, pectin, orange fiber and inulin, wherein the weight ratio of starch, pectin, orange fiber and inulin is (50~100):(1~3):(20~30):(200~300).

[0053] It should be noted that the proportions of starch, pectin, orange fiber, and inulin also affect the flavor and stability of the prepared yogurt. For example, when the starch content is lower than the above-mentioned proportions, the prepared yogurt has a thin texture and is prone to becoming watery after standing. When the starch content is higher than the above-mentioned proportions, the prepared yogurt has a strong pasty texture and an unpleasant taste. Similarly, when the pectin content is lower than the above-mentioned proportions, the prepared yogurt has a rough texture, and when the pectin content is higher than the above-mentioned proportions, the prepared yogurt has a sticky texture. Furthermore, when the orange fiber content is lower or higher than the above-mentioned proportions, the viscosity, cohesion, and texture all decrease, affecting the stability of the yogurt. The preferred weight ratio of starch, pectin, orange fiber, and inulin is 100:2:30:300. Yogurt prepared at this ratio has the best stability and taste.

[0054] It should be noted that in this invention, starch, pectin, orange fiber, and inulin work together to improve the stability of low-fat yogurt. Orange fiber, made from plump, healthy, and ripe oranges, has excellent thickening and stabilizing properties. It contains no additives, GMOs, or allergens and is produced under HACCP / PRP guidelines, making it a safe food additive. Inulin, derived from Jerusalem artichoke, chicory, and other plants, is rich in prebiotics and dietary fiber, making it a pure, natural, additive-free, and side-effect-free health food. Furthermore, inulin is an excellent fat substitute; when fully mixed with water, it forms a creamy structure, giving skim milk a smooth texture, which is crucial for addressing the issue of insufficient fat flavor in low-fat yogurt. In addition, adding inulin to yogurt can reduce whey separation and promote the absorption of calcium from dairy products, thus improving yogurt quality. It should also be noted that currently, inulin is primarily used in yogurt to provide dietary fiber, not for providing a fatty feel. In addition, pectin also has the ability to improve the overall smoothness of yogurt and to simulate the taste of fat to a certain extent. In this invention, pectin and inulin work together to support the fat flavor of yogurt.

[0055] It should also be noted that in this invention, starch and orange fiber work together to stabilize yogurt, and pectin and inulin can further increase the stability of low-fat yogurt. In addition, as mentioned above, pectin and inulin can also simulate the flavor of fat to a certain extent, so that the low-fat yogurt has a sufficient fat flavor.

[0056] Furthermore, the low-fat yogurt stabilizer of this invention contains a relatively high amount of dietary fiber, meeting consumers' demands for healthy eating. Moreover, the chemical names of the ingredients in the low-fat yogurt stabilizer of this invention are simple, which is advantageous for consumers who are increasingly concerned about product labels.

[0057] Furthermore, the taste of yogurt is closely related to its fat content. For various reasons, consumers often prefer to reduce the fat in dairy products, or even simply consume "fat-free dairy products," resulting in yogurt that is less like yogurt and has a poorer taste. The low-fat yogurt stabilizer in this invention can provide a fat flavor or simulate a fat flavor to restore the real taste of fat, making the yogurt have a rich fat flavor.

[0058] Preferably, starch D1 is selected. It should be noted that different starches affect the taste of the prepared yogurt, and starch D1 is preferred in this invention; yogurt prepared with starch D1 has better stability than yogurt prepared with other starch types.

[0059] Another embodiment of the present invention provides a low-fat yogurt, the raw materials of which include the aforementioned low-fat yogurt stabilizer and low-fat yogurt base; the weight of the low-fat yogurt stabilizer accounts for 4% to 5% of the weight of the raw materials. It should be noted that when the weight percentage of the low-fat yogurt stabilizer is less than 4%, the prepared yogurt has poor stability and poor taste, with insufficient fat flavor; when the weight percentage of the low-fat yogurt stabilizer is greater than 4%, the grainy and gelatinous texture is relatively heavy, affecting the taste; when the weight percentage of the low-fat yogurt stabilizer is 4.32% (starch accounts for 1% of the raw materials, orange fiber accounts for 0.3% of the raw materials, pectin accounts for 0.02% of the raw materials, and inulin accounts for 3% of the raw materials), the prepared yogurt has the best stability, the best taste, and a more harmonious fat flavor.

[0060] In some specific embodiments, the aforementioned low-fat yogurt base material includes sweetener, whole milk powder, skim milk powder, starter culture, and water; per 1000 parts by weight of raw materials, it includes: 50 to 60 parts by weight of sweetener, 40 to 60 parts by weight of whole milk powder, 40 to 60 parts by weight of skim milk powder, 40 to 50 parts by weight of low-fat yogurt stabilizer, 0.02 to 0.04 parts by weight of starter culture, and the balance being water.

[0061] In some specific embodiments, the above-mentioned starter culture can be a composite starter culture of starter culture 161 and starter culture 975; starter culture 161 is composed of *Streptococcus thermophilus*, *Lactobacillus delbrueckii* subsp. bulgaricus, and *Lactobacillus delbrueckii* subsp. lactis, while starter culture 975 is composed of *Streptococcus thermophilus* and *Lactobacillus delbrueckii* subsp. bulgaricus. It should be noted that the ratio of *Streptococcus thermophilus*, *Lactobacillus delbrueckii* subsp. bulgaricus, and *Lactobacillus delbrueckii* subsp. lactis in starter culture 161 can be adjusted according to specific circumstances, preferably 1:1:1; the ratio of *Streptococcus thermophilus* and *Lactobacillus delbrueckii* subsp. bulgaricus in starter culture 975 can be adjusted according to specific circumstances, preferably 1:1.

[0062] It should be noted that strain 161 consists of *Streptococcus thermophilus* Lactobacillus bulgaricus subsp. *species* and *Lactobacillus delbrueckii* Lactobacillus subsp. *species*; strain C975 consists of *Streptococcus thermophilus* Lactobacillus bulgaricus subsp. *species*. Furthermore, strain 161 produces a crisp and clean product with low viscosity, making it suitable for fermenting drinkable yogurt. Strain C975, on the other hand, is characterized by rapid fermentation, high viscosity, high thickness, and shear resistance; however, fermenting it alone can result in an overly sticky product. Therefore, combining strains 161 and C975 during fermentation yields a product with moderate viscosity and a fuller flavor.

[0063] In some specific embodiments, the preferred weight ratio of the 161 starter culture and the C975 starter culture is 1:1. It should be noted that the 161 and C975 starter cultures can be combined as needed, but a 1:1 ratio is preferred in this invention, as this ratio produces yogurt with the best taste and stability.

[0064] In some specific embodiments, the sweeteners mentioned above may include one or more of white sugar, maltitol, xylitol, erythritol, or polydextrose.

[0065] Another embodiment of the present invention provides a method for preparing the above-mentioned low-fat yogurt, characterized in that it includes: mixing low-fat yogurt base material and low-fat yogurt stabilizer evenly to obtain a mixture; homogenizing the mixture, sterilizing, inoculating with a starter culture, breaking the emulsion and cooling, and refrigerating at low temperature to obtain low-fat yogurt.

[0066] In some specific embodiments, the homogenization temperature can be 60℃~65℃, and the homogenization pressure can be 15MPa~20MPa. It should be noted that homogenization primarily refines the raw materials and prevents fat from floating to the surface. Furthermore, since the raw materials in this invention contain stabilizers, the homogenization temperature and pressure cannot be too high, as this will damage the stabilizer's structure; conversely, if the temperature and pressure are too low, the homogenization purpose will not be achieved. The homogenization effect is best when the homogenization temperature is 63℃ and the homogenization pressure is 17MPa, maximizing the refinement of the material without affecting the stabilizer.

[0067] In some specific embodiments, water can be heated to 50°C~55°C and then mixed with low-fat yogurt base and low-fat yogurt stabilizer, which can facilitate uniform mixing of the materials. Additionally, stirring can be performed during the mixing process to accelerate the dissolution of the materials in the water.

[0068] In some specific embodiments, the above-mentioned method for preparing low-fat yogurt may include the following steps:

[0069] (1) Weighing: Weigh whole milk powder, skim milk powder, white sugar, stabilizer, sweetener and water. Weigh the stabilizer separately, mix it well and then add it to the system.

[0070] (2) Mixing: Add the raw materials weighed in step (1) to water at 50℃~55℃ to the target system, and stir for 10min~20min to obtain a mixture;

[0071] (3) Homogenization: Heat the yogurt system to 60℃~65℃ and then homogenize it at 15Mpa~20Mpa;

[0072] (4) Sterilization: The homogenized mixture is pasteurized.

[0073] (5) Inoculation and fermentation: Inoculate the sterilized mixture with the starter culture and then ferment for 4 to 6 hours to obtain yogurt curds;

[0074] (6) Demulsification and cooling: Stir the coagulant obtained in step (5) for 1 min to 2 min at a speed of 12 rpm / min to 18 rpm / min, and then cool it down to 4℃ to obtain the demulsified yogurt emulsion;

[0075] (7) After filling and ripening, the yogurt liquid obtained in step (6) is filled and refrigerated in a 4℃ cold storage for 12h~24h to obtain low-fat yogurt.

[0076] To better understand the present invention, specific examples are provided below to further illustrate the content of the present invention, but the content of the present invention is not limited to the examples below.

[0077] In the following examples, viscosity was measured using a Brookfield DV2T viscometer with a measurement parameter of 10 rpm and 30 s. Texture and cohesion were measured using the method described in the reference "Zhao Xiao, Du Kun, Zhang Yuan. Effects of inulin on texture, rheological properties and microstructure of synbiotic yogurt [J]. Food Industry Technology, 2023, 44(1):6.", with an A / BE-35 probe and the following measurement conditions: measurement speed of 1 mm / s, advance distance of 10 mm, and sensing force of 0.5 g. Each sample was measured three times.

[0078] In the following examples, the water-holding capacity was determined using the same method as described in the reference "Zhao Xiao, Du Kun, Zhang Yuan. Effects of inulin on the texture, rheological properties and microstructure of synbiotic yogurt [J]. Food Industry Technology, 2023, 44(1):6." 30g of milk was placed in a 50mL centrifuge tube for fermentation. After refrigeration and ripening for 12 hours, the tube was centrifuged (3000×g, 4℃, 20min), weighed, and then the centrifuge tube was inverted for 10min and all whey was discarded. The tube was weighed again. Each sample was measured three times in parallel, and the average value was taken. Water-holding capacity (%) = m1 / m2×100 Where: m1 is the mass of the precipitate (g); m2 is the total mass of the yogurt (g).

[0079] In the following examples, stability (clarity index) analysis was performed using a LUMiSizer 6103-68 instrument at a wavelength of 865 nm, a temperature of 4 °C, and a speed of 3000 rpm / min.

[0080] In the following examples, the preparation of low-fat yogurt is carried out according to the following steps:

[0081] (1) Weighing: Weigh 49.5g of whole milk powder, 41g of skim milk powder, 60g of white sugar, stabilizer (a certain amount of stabilizer, which is weighed separately) and 0.04g of starter culture, mix them well and add them to the system;

[0082] (2) Mixing: Add the raw materials weighed in step (1) to 1000g of water at 50℃ and stir for 15min to obtain a mixture;

[0083] (3) Homogenization: Heat the mixture to 60°C and then homogenize it at 15 MPa.

[0084] (4) Sterilization: The homogenized mixture is pasteurized.

[0085] (5) Inoculation and fermentation: Inoculate the sterilized mixture with a starter culture, and then ferment at 42℃ for 6 hours to obtain yogurt curds;

[0086] (6) Demulsification and cooling: Stir the yogurt curd obtained in step (5) for 2 minutes at a speed of 12 rpm / min, and then cool it down to 4°C to obtain the demulsified yogurt emulsion;

[0087] (7) After filling and ripening, the yogurt emulsion obtained in step (6) is filled and refrigerated in a 4°C cold storage for 12 hours to obtain the low-fat yogurt of the present invention.

[0088] In the following examples, Fast 1.0 starter refers to YO-MIX FAST 1.0 LYO 200 DCU, sourced from Danisco; 161 starter refers to YO-MIX 161 LYO 200 DCU, sourced from Danisco; and c975 refers to starter Yo-C975-F, sourced from Hebei Yiran.

[0089] In the following examples, the total protein content of the whole milk powder and skim milk powder in the low-fat yogurt ingredients is 2.5g / 100g, and the fat content is 1.4g / 100g.

[0090] Example 1: Screening of Starch Types

[0091] In this embodiment of the invention, three modified starches were selected, designated as D1 (Hangzhou Prostar Starch Co., Ltd. T0220), D2 (Hangzhou Prostar Starch Co., Ltd. T5901), and D3 (Hangzhou Prostar Starch Co., Ltd. T2030), and their performance was tested. Specifically, in a conventional full-fat yogurt formula (per 1000g, 120g full-fat milk powder, 60g white sugar, 6‰ stabilizer, 0.04g starter culture Fast 1.0, and the remainder water), the formula was: 120g full-fat milk powder, 60g white sugar, and the stabilizer was added at a rate of 6‰ to the above-mentioned different types of starch. Then, the viscosity, texture, and cohesiveness were measured, and the starch with excellent performance was screened for subsequent preparation of low-fat yogurt.

[0092] The viscosity test results of the three starch-based yogurts are as follows: Figure 1As shown, the results indicate that the viscosity of yogurt prepared with added starch D1 is 6060 cP, while the viscosity of yogurt prepared with added D2 and D3 is 5520 cP and 5420 cP, respectively. That is, the viscosity of yogurt prepared with D1 is higher than that of the other two, and the texture and cohesion of D1 are better than those of D2 and D3.

[0093] In summary, this invention selects starch D1 as one of the ingredients for preparing the yogurt of this invention.

[0094] Example 2: Screening of starch addition amount

[0095] In this embodiment of the invention, Fast 1.0 was selected as the starter culture, and starch D1 was used as the stabilizer. Different addition amounts were set according to Table 1 below, and different samples were prepared according to the above-mentioned low-fat yogurt formula and preparation method. The viscosity, texture, cohesion, and taste of the prepared yogurt were tested, and the results are shown in Table 1 below.

[0096] Table 1 Screening of starch addition amount

[0097]

[0098] In addition, the viscosity, texture, and cohesiveness data in Table 1 above were plotted, and the viscosity, texture, and cohesiveness of yogurt prepared with different amounts of added starch D1 were shown in the figure below. Figure 4 , Figure 5 and Figure 6 As shown in the figure above and Table 1, it can be seen that with the increase of starch addition, the viscosity, texture, and cohesion of low-fat yogurt increase simultaneously; the greater the starch addition, the higher the values ​​of each indicator. However, excessive starch addition can easily lead to a pasty texture, affecting the taste of the yogurt. Therefore, considering the measured data indicators, taste evaluation, and observation of water separation, the optimal starch D1 addition amount was 10‰.

[0099] Example 3: Orange Fiber Addition Amount

[0100] In this embodiment of the invention, Fast 1.0 was selected as the starter, starch D1 and orange fiber were selected as stabilizers, and different amounts of orange fiber were added. Different samples were prepared according to the above low-fat yogurt formula and preparation method (see Table 2). The viscosity, texture, cohesion and water holding capacity of the obtained samples were tested respectively.

[0101] Table 2 Components of each group in Example 3

[0102]

[0103] The viscosity and water-holding capacity test results of different samples are as follows: Figure 7 and Figure 10As shown, the viscosity in the initial stage increased with the increase of orange fiber addition. The viscosity of the sample with 1‰ orange fiber added was significantly higher than that of the sample without added orange fiber, and the difference was statistically significant. p <0.01), and when the amount of orange fiber added was 3‰, the viscosity value showed its first peak. When the amount of orange fiber added was 4‰, the viscosity began to decrease, and as the amount of orange fiber increased further, the viscosity began to increase again. The possible reason is that the addition of orange fiber can perform hydration, which greatly increases the viscosity of the product. However, as the amount added increases, the water retention effect reaches a threshold. Therefore, increasing the amount added actually increases the competition between molecules, causing the viscosity and water holding capacity to decrease. This can be demonstrated by the measured water holding capacity. The water holding capacity reaches its maximum value when the amount of orange fiber added is 3‰, and the difference compared with sample 1 is significant. p <0.05), and then continued to decrease.

[0104] In addition, the texture test results of different samples are as follows: Figure 8 As shown, the trend of texture change is consistent with that of viscosity. When the amount of orange fiber added is 3‰, the texture reaches its first peak, and the difference compared with sample 1 is significant. p <0.01), indicating that at this addition amount, the addition of orange fiber can improve the texture of yogurt.

[0105] In addition, the cohesiveness (cohesiveness represents the viscosity of yogurt, reflecting the degree of aggregation within the yogurt. In the oral cavity, it manifests as the speed at which the yogurt spreads on the tongue; the greater the viscosity, the slower the spread) of different samples was tested as follows: Figure 9 As shown, the results indicate that the cohesive force of the product decreased when 1‰ or 2‰ of orange fiber was added compared to the product without orange fiber. When the addition amount reached 3‰, the cohesive force exceeded that of sample 1. Furthermore, the cohesive force gradually decreased as the addition amount increased. This result suggests that the addition of orange fiber can affect the cohesive force of the product. The reason for this is that orange fiber has certain suspension properties, and its distribution in yogurt may reconstruct the three-dimensional structure of the yogurt, leading to a decrease in the cohesive force of the yogurt.

[0106] In summary, the cohesion is enhanced to a certain extent when 3‰ of orange fiber is added. Considering other indicators, the preferred amount of orange fiber added in this invention is 3‰.

[0107] Example 4: Starch + Orange Fiber Test

[0108] Based on the test results of Examples 2 and 3, it was found that adding orange fiber can significantly improve the viscosity and texture of yogurt. However, further investigation during the experiment revealed that adding orange fiber alone had a relatively small supporting effect on the viscosity and texture of yogurt. Therefore, it is speculated that starch and orange fiber may form a new cross-linked network in the yogurt. Therefore, this example explored whether starch and orange fiber have a synergistic effect. Different samples were prepared according to the different stabilizer components shown in Table 3, following the above-mentioned low-fat yogurt formula (Fast 1.0 starter) and preparation method (see Table 3 for details). The viscosity, texture, cohesion, water-holding capacity, and clarification index of the samples in Table 3 were measured.

[0109] Table 3 Components of each group in Example 4

[0110]

[0111] The viscosity of the different samples prepared above is as follows: Figure 11 As shown, the results indicate that the viscosity of sample 3 is 8692 cP, which is higher than the sum of the viscosities of sample 1 (4820 cP) and sample 2 (3016 cP). Statistical analysis also shows that the viscosities of samples 1 and 2 significantly affect the viscosity of sample 3. p <0.001, p <0.0001), possibly because starch and orange fiber form a new gel network, which plays an important role in supporting viscosity, thus exhibiting a synergistic effect in viscosity.

[0112] The texture and cohesiveness of the different samples prepared above are as follows: Figure 12 and Figure 13 As shown, the results indicate that the addition of orange fiber alone is insufficient in supporting the texture of yogurt, and the texture and cohesiveness provided by orange fiber are worse than those of starch. In terms of cohesiveness, the cohesiveness of the product with orange fiber alone is the smallest, and the intermolecular attraction of the product is the weakest. This means that the stability is the worst under the same conditions, while the various indicators are significantly enhanced after combining with starch.

[0113] The water-holding capacity of the different samples prepared above is as follows: Figure 14 As shown, the results indicate that sample 2 has a poorer water retention capacity than sample 1, while the water retention capacity is further enhanced by combining starch and orange fiber, and the difference is statistically significant. p <0.05, p <0.01).

[0114] The clarification index of the different samples prepared above (the clarification index is negatively correlated with the stability of yogurt; a higher clarification index indicates a less stable system) is as follows: Figure 15As shown, the results indicated that the clarification indices of yogurt prepared from starch and orange fiber alone were 0.526 and 0.594, respectively, while the clarification index of sample 3, which added both ingredients, was 0.501. This was significantly lower than the clarification index of sample 3, which added only the two ingredients, and the difference was statistically significant compared to sample 2, which added orange fiber alone. p The value <0.05 indicates that the stability of adding orange fiber alone is the worst, while sample 3, which uses starch and orange fiber in combination, is more stable.

[0115] In summary, starch and orange fiber can play a synergistic role as a stabilizing system in yogurt, but the water-holding capacity of the entire product system is still not good enough, and the texture is not smooth enough. Therefore, in this embodiment of the invention, pectin is added to improve the water-holding capacity and improve the texture of the product.

[0116] Example 5: Pectin Addition Amount

[0117] To improve the overall quality and taste of the product, this invention investigated the effects of pectin on the viscosity, texture, cohesion, water-holding capacity, and clarification index of yogurt. In this invention, starch D1, orange fiber, and pectin were used as stabilizers, and different amounts of pectin were added (see Table 4). Different samples were prepared according to the low-fat yogurt formula (Fast 1.0 starter) and preparation method described above.

[0118] Table 4 Components of each group in Example 5

[0119]

[0120] The viscosity, texture, cohesion, water-holding capacity, clarification index, and mouthfeel of the different samples in Table 4 above are shown in Table 5 below.

[0121] Table 5. Measurement data and taste results for each group in Example 5.

[0122]

[0123] In addition, graphs were plotted on the different data in Table 5, as follows: Figure 16 , Figure 17 , Figure 18 , Figure 19 and Figure 20 As shown, the details are as follows:

[0124] Viscosity of different samples as follows Figure 16 As shown, the results indicate that the viscosity of the sample increases with the increase of pectin addition. When the pectin addition reaches 0.3‰, the difference is significant compared with sample 1 without pectin. p<0.05), and as the amount of pectin added increases, the product viscosity further increases, and the difference becomes more significant, indicating that pectin plays an important role in improving the viscosity of the product.

[0125] Texture of different samples as follows Figure 17 As shown, the results indicate that the addition of pectin improved the texture of the yogurt to some extent, but there was no significant difference in texture compared to sample 1 without added pectin. p> (0.05). Furthermore, the increase in texture was not significant with increasing addition amount, indicating that the addition of pectin did not significantly improve texture at the amount added in this experiment, which may be due to the small amount of pectin added.

[0126] Texture of different samples as follows Figure 18 As shown, the results indicate that the variation in cohesion among the sample groups was small, and there was no significant difference compared to the control group. p >0.05).

[0127] Water holding capacity of different samples as follows Figure 19 As shown, the results indicate that the addition of pectin significantly improved the water-holding capacity and stability of the product. The water-holding capacity of sample 1 without pectin was 49.43%, while the water-holding capacities of samples 2 to 6 with different amounts of pectin were 52.87%, 52.90%, 52.01%, 53.10%, and 54.33%, respectively, showing a dose-dependent increasing trend and a significant improvement in water-holding capacity compared to sample 1.

[0128] Clarity index of different samples as follows Figure 20 As shown, the results indicate that when the pectin addition reaches 0.2‰, the clarifying index is significantly different from that of sample 1. p <0.05 indicates that the stability of the yogurt is enhanced.

[0129] In addition, the embodiments of the present invention also evaluated the taste of each sample. The results showed that the addition of pectin can improve the roughness of yogurt and increase its smoothness. However, when the amount of pectin added exceeds 0.2‰, the product tastes stickier and becomes greasy as the amount of pectin increases further.

[0130] In summary, when the amount of pectin added reaches 0.2‰, the water-holding capacity and stability of yogurt can be improved. However, as the amount of pectin added increases, the improvement is not significant. Based on the taste results, the preferred amount of pectin added in this invention is 0.2‰.

[0131] Example 6 Inulin addition amount

[0132] In this embodiment of the invention, in order to test the role of inulin in the stabilizer of the present invention, starch D1, orange fiber, pectin and inulin were set as stabilizers, and different amounts of inulin were set (see Table 6). Different samples were prepared according to the low-fat yogurt formula (Fast 1.0 starter) and preparation method of the above-mentioned low-fat yogurt.

[0133] Table 6. Components of each group in Example 6

[0134]

[0135] The prepared samples were subjected to tests for viscosity, texture, cohesion, water-holding capacity, clarifying index, and mouthfeel. The results are as follows: Figure 21 , Figure 22 , Figure 23 , Figure 24 and Figure 25 As shown, the details are as follows:

[0136] The viscosity of different samples is as follows: Figure 21 As shown, the results indicate that the viscosity of the sample with only inulin added was 4608 cP, the viscosity of sample 1 with added starch, orange fiber, and pectin was 8844 cP, while the viscosity of sample 3 with all ingredients added reached 9504 cP. The viscosity of sample 1 was significantly different from that of sample 2. p <0.0001), compared to sample 1, the viscosity of sample 3 increased by 7.46%, which is statistically significant. p The value <0.05 indicates that the addition of inulin has a promoting effect on improving the overall viscosity.

[0137] The texture of different samples, such as Figure 22 As shown in the results, sample 2 has the worst texture and is significantly different from sample 1. p <0.05), while sample 3 showed no significant difference in texture compared to sample 1 ( p >0.05), indicating that the addition of inulin to the system of starch, orange fiber, and pectin did not significantly improve the texture.

[0138] The cohesive properties of different samples are as follows: Figure 23 As shown, the results indicate that sample 3 showed no significant difference from sample 1, while sample 3 showed a significant difference from sample 2. p <0.05).

[0139] The water-holding capacity of different samples is as follows: Figure 24 As shown, the results indicate that sample 3 had a 5.44% higher water-holding capacity than sample 1, but the difference was not statistically significant. p >0.05).

[0140] Clarity index of different samples as follows Figure 25As shown, the results indicate that the clarification index of sample 2 (with only inulin added) was 0.536, the clarification index of sample 1 was 0.499, and the clarification index of sample 3 was 0.462, which was the lowest, indicating stronger stability. The difference between sample 2 and sample 3 was statistically significant. p <0.05), while there was no significant difference between sample 1 and sample 3 ( p >0.05), indicating that inulin plays an important role in the stability of yogurt.

[0141] In addition, based on taste, Sample 2 had a poor texture, a thin mouthfeel, and poor smoothness. Sample 3, with the addition of starch, orange fiber, pectin, and inulin, improved the overall weight and smoothness of the product, and further enhanced the missing fatty flavor.

[0142] In conclusion, inulin not only plays a positive role in improving the stability of yogurt products, but also plays an important role in improving the taste and supplementing the fat flavor.

[0143] Example 7 Fermentation Test of Microbial Strains

[0144] This invention further explores the differences between single-strain fermentation and co-fermentation after the use of compound stabilizers. The starter cultures were Fast 1.0 and 161 / c975 (weight ratio 1:1), and starch D1, orange fiber, pectin and inulin were used as stabilizers. Different amounts of inulin were added (see Table 7). Different samples were prepared according to the above-mentioned low-fat yogurt formula and preparation method.

[0145] Table 7. Components of each group in Example 7

[0146]

[0147] The different yogurt samples prepared according to Table 7 above were tested for clarification index, viscosity, texture, cohesion, and water-holding capacity. The results are as follows: Figure 26 (Clarification Index) Figure 27 (Viscosity) and Figure 28 (Texture, cohesion, and water-holding capacity are represented on the horizontal axis, from left to right, respectively.) The results are shown below:

[0148] Compared to sample 1, sample 2 showed a 9.01% increase in viscosity and a 9.29% increase in texture, with statistically significant differences (p < 0.01%). < (0.05), the increase in cohesion was not significant, increasing by 6.30%, while the increase in water holding capacity was 3.17%;

[0149] The clarification index of sample 1 was 0.462, and that of sample 2 was 0.458. The results showed that the stability of sample 2 was further improved, indicating that the combined fermentation of the strains can further enhance the weight of the yogurt and bring a fuller taste.

[0150] Sample 1 was fermented with a single-strain microbial culture using a compound stabilizer, while Sample 2 was fermented with a compound microbial culture of different characteristics. Compared to Sample 1, Sample 2 had a fuller, thicker, and more harmonious flavor. According to the test results, Sample 2 had a 9% higher viscosity, a 9.2% higher texture, a 6.3% higher cohesiveness, and a 3.2% higher water-holding capacity than Sample 1.

[0151] In addition, during stability testing, it was found that the clarification index of sample 2 was lower than that of sample 1, indicating that sample 2 was more stable than sample 1.

[0152] In summary, compared with sample 1, sample 2 showed significant improvements in viscosity, texture, mouthfeel, stability, and water-holding capacity; that is, strain 161 / c975 is more conducive to the fermentation of yogurt in this invention.

[0153] Example 8: Comparison of low-fat and full-fat yogurt

[0154] In order to test the difference between low-fat yogurt and full-fat yogurt prepared by the low-fat yogurt preparation method of the present invention, the following experiment was designed as shown in Table 8, and different yogurt samples were obtained.

[0155] Table 8 Components of each group in Example 8

[0156]

[0157] The study conducted sensory evaluations on three groups of samples. The evaluations and scores were performed by professional sensory evaluation specialists, and the results are shown in Table 9 below (Note: Each evaluation has a maximum score of 10 points, and the evaluations were conducted by 15 people).

[0158] Table 9. Taste evaluation results of sample from Example 8

[0159]

[0160] As shown in Table 9 above, sensory evaluation revealed that Sample 1, the low-fat yogurt, was inferior to Samples 2 and 3 in terms of gelation state and texture. Sample 1 also exhibited significant water separation after 1-2 days, and its taste was thin, lacking milky and fatty flavors. In contrast, Sample 2 had a continuous and full appearance, a good gelation state, and showed little difference in appearance compared to Sample 3, but its texture was superior. Furthermore, sensory evaluation showed that Sample 2, prepared using the low-fat yogurt preparation method of this invention, had almost no difference in taste from Sample 3, and achieved higher scores in thickness, smoothness, and sweetness / sourness, with an overall score improvement of 8.70%.

[0161] Example 9: Weight ratio of starter culture 161 and starter culture C975

[0162] In this embodiment of the invention, the effect of the weight ratio of starter culture 161 and starter culture C975 on the prepared yogurt was investigated. The starter culture was set at 161 / C975 (weight ratio 1:1), 161 / C975 (weight ratio 2:1), and 161 / C975 (weight ratio 1:2), respectively. Starch D1, orange fiber, pectin, and inulin were used as stabilizers, and different amounts of inulin were added (see Table 10). Different samples were prepared according to the above-mentioned low-fat yogurt formula and preparation method.

[0163] Table 10 Components of each group in Example 9

[0164]

[0165] The viscosity, texture, cohesion, and water-holding capacity of different samples in Table 10 above were tested, and the results are shown in Table 11 below.

[0166] Table 11 Measurement data for each sample in Example 9

[0167]

[0168] As shown in Table 11 above, the overall performance of samples 1 and 3 is worse than that of sample 2. However, after evaluation by the sensory evaluators, it was found that sample 3 was a bit sticky and its taste was not as good as that of sample 1. Therefore, the preferred weight ratio of starter culture 161 to starter culture c975 is 1:1.

[0169] In summary, the use of the compound stabilizer and the compound fermentation of the starter culture described in this invention increases the consistency, texture, mouthfeel, and fat flavor of low-fat yogurt, making it indistinguishable from full-fat yogurt. That is, the compound stabilizer and starter culture method provided by this invention plays a crucial role in addressing the shortcomings of low-fat yogurt. Furthermore, the method provided by this invention allows for product production without altering existing equipment and processes, and the produced product has no significant difference in taste from full-fat yogurt, which is of great significance for addressing consumers' demand for low-fat diets and for enterprises to reduce costs and increase efficiency.

[0170] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A low-fat yogurt, characterized in that, Its raw materials include low-fat yogurt stabilizer and low-fat yogurt base; the weight of low-fat yogurt stabilizer accounts for 4% to 5% of the weight of raw materials; the low-fat yogurt stabilizer includes: starch, pectin, orange fiber and inulin, and the weight ratio of starch, pectin, orange fiber and inulin is (50 to 100): (1 to 3): (20 to 30): (200 to 300); the starch selected is starch D1, which is T0220 starch from Hangzhou ProStar Starch Co., Ltd.

2. The low-fat yogurt according to claim 1, characterized in that, The weight ratio of starch, pectin, orange fiber and inulin is 100:2:30:

300.

3. The low-fat yogurt according to claim 1 or 2, characterized in that, The base ingredients for low-fat yogurt include sweeteners, whole milk powder, skim milk powder, starter culture, and water; per 1000 parts by weight, the ingredients include: 50 to 60 parts by weight of sweetener, 40 to 60 parts by weight of whole milk powder, 40 to 60 parts by weight of skim milk powder, 40 to 50 parts by weight of low-fat yogurt stabilizer, 0.02 to 0.04 parts by weight of starter culture, and the remainder water.

4. The low-fat yogurt according to claim 3, characterized in that, The starter culture was a combination of starter culture 161 and starter culture 975. Starter culture 161 was composed of Streptococcus thermophilus, Lactobacillus delbrueckii subsp. bulgaricus, and Lactobacillus delbrueckii subsp. lactis. Starter culture 975 was composed of Streptococcus thermophilus and Lactobacillus delbrueckii subsp. bulgaricus.

5. The low-fat yogurt according to claim 4, characterized in that, The weight ratio of 161 starter culture to C975 starter culture is 1:

1.

6. The low-fat yogurt according to claim 4 or 5, characterized in that, Sweeteners include one or more of white sugar, maltitol, xylitol, erythritol, or polydextrose.

7. The method for preparing low-fat yogurt according to any one of claims 1 to 6, characterized in that, include: The low-fat yogurt base and low-fat yogurt stabilizer are mixed evenly to obtain a mixture; the mixture is then homogenized, sterilized, inoculated with a starter culture, demulsified and cooled, and then refrigerated at low temperature to obtain low-fat yogurt.

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