Flavored yogurt and method for making the same

Abstract

The application provides a flavored yogurt and a preparation method thereof, and the preparation method comprises the following steps: 1) inoculating fermentation bacteria and lactase in concentrated milk, and fermenting to a fermentation end point to obtain a fermentation product; 2) demulsifying, cooling and post-ripening the fermentation product to obtain the flavored yogurt; the lactose content in the concentrated milk is 7-12.5 wt%; the pH at the fermentation end point is 4.4-4.6, and the acidity is 100-125 °T. The application combines the formula and the process to prepare the yogurt product with a proper sour-sweet ratio without adding any sweetening substance, and only by using the milk itself.

Description

Technical Field

[0001] This invention relates to the field of fermented dairy product technology, and in particular to a flavored yogurt and its preparation method. Background Technology

[0002] Yogurt's sour taste comes from the gradual metabolism of lactose into lactic acid during fermentation. Simultaneously, the metabolism of some lactose reduces its sweetness, thus intensifying the sourness. To achieve a suitable sweet-sour ratio for easier consumption, industrially produced yogurt typically uses added sugar, sweeteners, or by adding jams or honey to enhance sweetness and offset the sourness. However, as consumers become more health-conscious and aware of the negative impacts of added sugars and sweeteners, they increasingly demand clean labels—minimal ingredients and no additives. Meeting these consumer demands by achieving a suitable sweet-sour ratio without adding any exogenous sweeteners is a challenge facing the industry. Summary of the Invention

[0003] In view of the shortcomings of the prior art described above, the purpose of this invention is to provide a flavored yogurt and a method for preparing the same, in order to solve the problems in the prior art.

[0004] To achieve the above and other related objectives, the present invention is obtained through the following technical solution.

[0005] A method for preparing flavored yogurt includes the following steps: inoculating concentrated milk with fermentation bacteria and lactase, fermenting, and obtaining flavored yogurt;

[0006] The lactose content in the concentrated milk is 7–12.5 wt%.

[0007] The final pH of the fermentation was 4.4–4.6, and the acidity was 100–125°T.

[0008] The pH at the fermentation endpoint can be 4.4, 4.55, 4.5, or 4.6. Preferably, it is 4.5–4.6. More preferably, it is 4.55–4.6.

[0009] The acidity at the fermentation endpoint can be 100°T, 105°T, 110°T, 115°T, 118°T, 120°T, or 125°T. Preferably, it is 110–120°T. More preferably, it is 115–118°T.

[0010] The lactose content in the concentrated milk can be 7wt%, 7.5wt%, 8wt%, 8.5wt%, 9wt%, 9.5wt%, 10wt%, 10.5wt%, 11wt%, 11.5wt%, 12wt%, or 12.5wt%.

[0011] Preferably, the protein content in the concentrated milk is 4.2–8.8 wt%. For example, it can be 4.2 wt%, 4.8 wt%, 4.9 wt%, 5.1 wt%, 6.0 wt%, 6.27 wt%, 6.4 wt%, 7.0 wt%, 8.0 wt%, 8.5 wt%, or 8.8 wt%.

[0012] Preferably, the raw milk is obtained through a concentration process, with a concentration ratio of 1.4 to 2.5 times. The concentration ratio can be 1.4 times, 1.5 times, 1.7 times, 1.9 times, 2 times, 2.2 times, or 2.5 times. Preferably, it is 1.5 to 2 times. More preferably, it is 1.7 to 1.9 times.

[0013] In this application, the concentration ratio is the mass ratio of the solution before concentration to the retentate after concentration per unit time.

[0014] More preferably, the raw milk is selected from raw cow's milk.

[0015] More preferably, the raw milk has a protein content of 3.0–3.5 wt% and a fat content of 3.6–4.5 wt%. For example, the protein content of the raw milk can be 3.0 wt%, 3.1 wt%, 3.2 wt%, 3.3 wt%, 3.4 wt%, or 3.5 wt%, and the fat content can be 3.6 wt%, 3.8 wt%, 4.0 wt%, 4.2 wt%, 4.4 wt%, or 4.5 wt%.

[0016] More preferably, the raw milk has a protein content of 3.0 to 3.3 wt% and a fat content of 3.6 to 4.0 wt%.

[0017] More preferably, the raw milk has a protein content of 3.2 to 3.3 wt% and a fat content of 3.8 to 4.0 wt%.

[0018] More preferably, the concentration process is nanofiltration.

[0019] More preferably, the concentration temperature is 4–50°C. For example, it can be 4°C, 10°C, 15°C, 20°C, 30°C, 40°C, or 50°C.

[0020] Preferably, after fermentation, demulsification, cooling, and post-ripening are also carried out.

[0021] More preferably, the demulsification is performed by stirring.

[0022] More preferably, the stirring speed is 20-30 r / min and the demulsification time is 2-3 min.

[0023] More preferably, the cooling temperature is 2–8°C.

[0024] More preferably, the temperature of the post-ripening treatment is 2 to 8°C. For example, it can be 2°C, 3°C, 4°C, 5°C, 6°C, 7°C, or 8°C.

[0025] More preferably, the post-ripening treatment takes 10 to 24 hours.

[0026] If the amount of lactase used is too small, the lactose in the concentrated milk cannot be completely broken down, affecting the sweet-sour ratio of the flavored yogurt. Therefore, based on the mass of the concentrated milk, the amount of lactase added is preferably 0.2–0.5 wt‰. For example, the amount of lactase added can be 0.2 wt‰, 0.3 wt‰, 0.4 wt‰, or 0.5 wt‰. More preferably, the amount of lactase added is 0.3–0.5 wt‰. Even more preferably, it is 0.4–0.5 wt‰.

[0027] Preferably, the fermentation strain is selected from one or two of Lactobacillus bulgaricus and Streptococcus thermophilus.

[0028] More preferably, the fermentation strain is a mixture of Lactobacillus bulgaricus and Streptococcus thermophilus, wherein the live count ratio of Lactobacillus bulgaricus to Streptococcus thermophilus is 1:(50-100).

[0029] Preferably, the inoculum size of the fermentation strain is 1×10⁻⁶. 6 ~2×10 6 CFU / mL.

[0030] Preferably, the fermentation temperature is 40–44°C.

[0031] Preferably, the fermentation time is 6 to 8 hours.

[0032] Preferably, the fermentation environment is a commonly used fermentation environment in the art.

[0033] Preferably, the concentrated milk is homogenized and sterilized before the addition of lactase.

[0034] More preferably, the sterilization treatment is to keep warm at 90-95°C for 5-7 minutes.

[0035] More preferably, the homogenization process is carried out at a temperature of 55–65°C.

[0036] More preferably, the homogenization process includes a primary homogenization process and a secondary homogenization process.

[0037] More preferably, the pressure of the primary homogenization process is 16–20 MPa.

[0038] More preferably, the pressure of the secondary homogenization process is 2 to 5 MPa.

[0039] The present invention also discloses a flavored yogurt.

[0040] Preferably, the flavored yogurt has a sweetness of 2.5 to 5.0 and a sweet-sour ratio of 20 to 40.

[0041] This invention provides a flavored yogurt and its preparation method, which has the following beneficial effects:

[0042] This invention achieves a suitable sweet-to-sour yogurt product without adding any additional sweeteners through a combination of formulation and processing methods. The method primarily involves increasing the lactose content to a specific range (7-12.5 wt%) through a specific concentration ratio, adding lactase to break down lactose into glucose and galactose to enhance sweetness, and optimizing the pH and acidity at the fermentation endpoint. The combined effect of these techniques results in a yogurt that is rich in nutrients, creamy, and has a pleasant sweet-to-sour taste. Furthermore, due to the concentration of protein, the yogurt exhibits minimal acidity changes during its shelf life, resulting in superior taste stability. Detailed Implementation

[0043] The following specific embodiments illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification.

[0044] Before further describing specific embodiments of the present invention, it should be understood that the scope of protection of the present invention is not limited to the specific embodiments described below; it should also be understood that the terminology used in the embodiments of the present invention is for describing specific embodiments and not for limiting the scope of protection of the present invention. Test methods in the following embodiments that do not specify specific conditions are generally performed under conventional conditions or as recommended by the respective manufacturers.

[0045] When numerical ranges are given in the embodiments, it should be understood that, unless otherwise stated in the present invention, both endpoints of each numerical range and any value between the two endpoints may be selected. Unless otherwise defined, all technical and scientific terms used in this invention have the same meaning as commonly understood by one of ordinary skill in the art. In addition to the specific methods, apparatus, and materials used in the embodiments, based on the knowledge of the prior art possessed by one of ordinary skill in the art and the description of this invention, any prior art methods, apparatus, and materials similar to or equivalent to those described, apparatus, and materials in the embodiments of this invention may be used to implement the present invention.

[0046] Example 1

[0047] This embodiment provides a more specific flavored yogurt, the preparation method of which is as follows:

[0048] (1) Preparation of fermentation products: 100L of raw milk (protein content 3.0wt%, fat content 3.6wt%) was fermented at 4℃

[0049] The milk was concentrated by nanofiltration at a concentration ratio of 1.7 to obtain concentrated milk, which contained 8.5 wt% lactose and 5.1 wt% protein. After homogenization and sterilization, it was inoculated with a starter culture (1×10⁻⁶). 6 CFU / mL inoculum (Lactobacillus bulgaricus and Streptococcus thermophilus viable count ratio of 1:50) and 11.8g (addition amount of 0.2wt‰).

[0050] Lactase fermentation was carried out to the fermentation endpoint (pH 4.55, acidity 125°T) to obtain the fermentation product. Homogenization was performed at 60°C, with a primary homogenization pressure of 20 MPa and a secondary homogenization pressure of 5 MPa. Sterilization conditions were as follows:

[0051] The temperature was 90℃, and the incubation period was 7 minutes. The fermentation conditions were: temperature 40℃.

[0052] (2) The fermentation product is demulsified, cooled and matured to obtain the flavored yogurt.

[0053] Demulsification conditions: Stirring for 3 minutes at a stirring speed of 25 r / min. Cooling temperature: 5℃. Post-ripening conditions: Post-ripening at 5℃ for 24 hours.

[0054] Example 2

[0055] This embodiment provides a more specific flavored yogurt. The preparation method is basically the same as that in Example 1, except that: in step (1), the protein content of the raw milk is 3.3wt%, the fat content is 3.8wt%, the concentration temperature is 10℃, the concentration ratio is 1.9 times, the lactose content in the concentrated milk is 9.5wt%, and the protein content is 6.27wt%. The amount of lactase added is 26.3g (0.5wt‰); the fermentation endpoint is pH 4.5 and acidity is 115°T.

[0056] In step (2), the post-ripening temperature is 8℃.

[0057] Example 3

[0058] This embodiment provides a more specific flavored yogurt. The preparation method is basically the same as that in Example 1, except that: in step (1), the protein content of the raw milk is 3.2 wt%, the fat content is 4.0 wt%, the concentration temperature is 15°C, the concentration ratio is 1.5 times, the lactose content in the concentrated milk is 7.5 wt%, and the protein content is 4.8 wt%. The amount of lactase added is 20 g (0.3 wt‰); the fermentation endpoint is pH 4.4 and acidity is 118°T.

[0059] In step (2), the post-ripening temperature is 6℃.

[0060] Example 4

[0061] This embodiment provides a more specific flavored yogurt. The preparation method is basically the same as that in Example 1, except that: in step (1), the protein content of the raw milk is 3.5wt%, the fat content is 4.5wt%, the concentration temperature is 15℃, the concentration ratio is 1.4 times, the lactose content in the concentrated milk is 7wt%, and the protein content is 4.9wt%. The amount of lactase added is 28.6g (0.4wt‰); the fermentation endpoint is pH 4.6 and acidity is 100°T.

[0062] In step (2), the post-ripening temperature is 5℃.

[0063] Example 5

[0064] This embodiment provides a more specific flavored yogurt. The preparation method is basically the same as that in Example 1, except that: in step (1), the protein content of the raw milk is 3.4 wt%, the fat content is 3.8 wt%, the concentration temperature is 50°C, the concentration ratio is 2.5 times, the lactose content in the concentrated milk is 12.5 wt%, and the protein content is 8.5 wt%. The amount of lactase added is 20 g (0.5 wt‰); the fermentation endpoint is pH 4.55 and acidity is 120°T.

[0065] In step (2), the post-ripening temperature is 7℃.

[0066] Example 6

[0067] This embodiment provides a more specific flavored yogurt. The preparation method is basically the same as that in Example 1, except that: in step (1), the protein content of the raw milk is 3.2wt%, the fat content is 4.4wt%, the concentration temperature is 40℃, the concentration ratio is 2 times, the lactose content in the concentrated milk is 10wt%, and the protein content is 6.4wt%. The amount of lactase added is 20g (0.4wt‰); the fermentation endpoint is pH 4.5 and acidity is 110°T.

[0068] In step (2), the post-ripening temperature is 7℃.

[0069] Comparative Example 1

[0070] This comparative example is the comparative example of Example 1, except that no lactase is added.

[0071] Comparative Example 2

[0072] This comparative example is the same as Example 2, except that the concentration ratio is 1.2 times, resulting in a lactose content of 6 wt% and a protein content of 3.96 wt% in the concentrated milk.

[0073] Comparative Example 3

[0074] This comparative example is the comparative example of Example 3, except that: fermentation endpoint: pH 4.3, acidity 130°T.

[0075] Comparative Example 4

[0076] This comparative example is the comparative example of Example 4, except that the raw milk is not concentrated by nanofiltration.

[0077] The flavored yogurts prepared in Examples 1-6 and Comparative Examples 1-4 were tested for their sweet-sour ratio. The test results are shown in Table 1. The test method was as follows:

[0078] Acidity: Phenolphthalein indicator method in GB 5009.239-2016.

[0079] Sweetness: With sucrose sweetness as 1, lactose sweetness as 0.7, glucose sweetness as 0.75, and galactose sweetness as 0.27, the calculation method is: the content of the remaining sugar in the system multiplied by the sum of their corresponding sweetness values.

[0080] Test method for residual lactose and glucose content: high performance liquid chromatography in GB5009.8-2016, galactose content is calculated as an equal amount of glucose.

[0081] Sweet-sour ratio = acidity / sweetness.

[0082] Table 1 Sweet and sour ratio

[0083]

[0084]

[0085] The flavored yogurts prepared in Examples 1-6 and Comparative Examples 1-4 were subjected to taste tests.

[0086] A total of 100 people were selected for the test, including 50 men with an average age of 33 and 50 women with an average age of 28. They were asked to rate the sweet and sour taste.

[0087] Each person tastes a flavored yogurt on an empty stomach at 8 a.m. every day and then scores it, for 10 consecutive days.

[0088] The average score was taken from 100 people.

[0089] The scoring criteria are shown in Table 2. The scoring table is shown in Table 3.

[0090] Table 2

[0091]

[0092] Table 3

[0093]

[0094]

[0095] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the invention. Any person skilled in the art can modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by those skilled in the art without departing from the spirit and technical concept disclosed in the present invention should still be covered by the claims of the present invention.

Claims

1. A method for preparing flavored yogurt, characterized in that, The process includes the following steps: inoculating concentrated milk with fermentation starters and lactase, fermenting until the fermentation endpoint, and obtaining flavored yogurt; The concentrated milk contains 7-12.5 wt% lactose and 4.2-8.8 wt% protein. The pH at the fermentation endpoint is 4.4-4.6, and the acidity is 100-125°T. The concentrated milk is obtained from raw milk through a concentration process, with a concentration ratio of 1.4 to 2.5 times; The concentration process is nanofiltration; Based on the mass of concentrated milk, the amount of lactase added is 0.2~0.5 wt‰; The inoculum size of the fermentation strain is 1×10⁻⁶. 6 ~2×10 6 CFU / mL, wherein the fermentation strain is a mixture of Lactobacillus bulgaricus and Streptococcus thermophilus, and the viable count ratio of Lactobacillus bulgaricus to Streptococcus thermophilus is 1:(50~100). The flavored yogurt has a sweet-sour ratio of 20 to 40 and a sweetness of 2.5 to 5.

0.

2. The preparation method according to claim 1, characterized in that, After fermentation, demulsification, cooling, and post-ripening processes are carried out.

3. The preparation method according to claim 2, characterized in that, The raw milk is selected from raw cow's milk; And / or, the concentration temperature is 4–50°C.

4. The preparation method according to claim 1, characterized in that, Includes one or more of the following technical features: The fermentation temperature is 40~44℃; The fermentation time is 6-8 hours; The concentrated milk is homogenized and sterilized before the addition of lactase.

5. The preparation method according to claim 4, characterized in that, The homogenization process is carried out at a temperature of 55~65℃; And / or, the sterilization treatment is to keep warm at 90~95 ℃ for 5~7 minutes.

6. The preparation method according to claim 5, characterized in that, The homogenization process includes primary homogenization and secondary homogenization.

7. The preparation method according to claim 6, characterized in that, The pressure of the primary homogenization process is 16~20MPa; And / or, the pressure of the secondary homogenization process is 2~5 MPa.

8. A flavored yogurt, characterized in that, It is prepared by the preparation method according to any one of claims 1 to 7.

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