Liupao tea yoghourt and preparation method thereof

Abstract

The invention relates to the technical field of preparation of tea-flavored yoghurt, and discloses Liupu tea yoghurt and a preparation method thereof. The preparation method of the Liupao tea yoghourt comprises the following steps: adding Liupao tea into milk for leaching, removing tea residues after leaching is finished, adding white granulated sugar, and stirring for dissolving to obtain emulsion; adding a fermentation strain into the emulsion, uniformly stirring, putting into a biochemical incubator, and carrying out constant-temperature fermentation to obtain crude tea yoghourt; and refrigerating and after-ripening the crude tea yoghurt to obtain the Liupu tea yoghurt finished product. According to the preparation method disclosed by the invention, the unique aroma of the Liupao tea and the mellowness of the yoghourt are perfectly combined, the unique flavor of the Liupao tea is excited by adding the specific microbial fermentation agent, and meanwhile, the nutritional value and the health-care function of the yoghourt are also reserved; the Liupao tea yoghourt prepared by the invention not only meets the enjoyment of taste buds, but also is nutritional and healthy.

Description

Technical Field

[0001] The present application relates to the technical field of tea-flavored yogurt preparation, and in particular to a Liubao tea-flavored yogurt and a preparation method thereof. Background Art

[0002] Liubao tea, a dark tea from Baozhen, is characterized by its firm, uniform appearance, oily dark brown color, pure aroma or hints of betel nut, rich red soup, and mellow flavor. Liubao tea is known for its unique aroma and health benefits, characterized by its red, rich, aged, and mellow flavor. Its distinctive betel nut aroma is one of the sensory qualities that distinguishes it from other dark teas, such as Pu'er and Fuzhuan tea. Liubao tea is rich in tea polyphenols and catechins, which have lipid-lowering, glucose metabolism-regulating, immune-boosting, and antioxidant properties. Modern Liubao tea utilizes a unique cold-water fermentation technique, which, compared to traditional methods, allows for faster conversion of ingredients and shortens the production cycle, resulting in a rich, red soup with a mellow, aged flavor.

[0003] Yogurt is a fermented dairy product rich in active probiotics, produced by homogenizing and pasteurizing fresh or reconstituted milk and then inoculating it with Lactobacillus bulgaricus and Streptococcus thermophilus. Yogurt contains a variety of vitamins, proteins, and lactic acid bacteria, which have been shown to improve intestinal flora, prevent lactose intolerance, boost immunity, and enhance mineral absorption. Its unique flavor, high nutritional value, and excellent health benefits are highly sought after by consumers. During the fermentation process, Streptococcus thermophilus and Lactobacillus bulgaricus exhibit a synergistic effect. The coagulation mechanism of yogurt begins with the rapid growth of thermophilic Streptococcus, which breaks down lactose into lactic acid. As the pH of the milk solution drops from 6.5 to 5.5, the growth of thermophilic Streptococcus slows, while the growth of Lactobacillus bulgaricus accelerates. The synergistic effect of these two factors lays the foundation for the distinctive yogurt flavor. Next, as the pH of the milk solution drops further to 5.0, Lactobacillus bulgaricus takes control of the yogurt's fermentation. Finally, when the pH of the milk solution drops to around 4.6, casein begins to aggregate, and the milk solution begins to coagulate. This fermentation process, regulated by microorganisms, not only gives yogurt its unique flavor but also ensures its health benefits.

[0004] With the development of society, consumers' health awareness is constantly strengthening, and their demands are becoming increasingly diversified. Ordinary yogurt products can no longer meet market demand. Innovations in tea yogurt offer modern consumers a new beverage option that not only satisfies the taste buds but also provides health benefits. Research on dark tea-flavored yogurt has made considerable progress, particularly in the areas of Pu'er tea and Fuzhuan tea flavored yogurt, with some notable reports. For example, Wu Haiyue et al. used fresh yak milk as raw material and Pu'er tea powder as auxiliary material to produce Pu'er tea-flavored yak yogurt. The resulting Pu'er tea yak yogurt has a mellow texture, delicate taste, and a moderate sweetness and sourness. Liu Dong et al. also used Fuzhuan tea and milk powder to create a yogurt with the unique aroma and flavor of Fuzhuan tea, which is well-received.

[0005] However, research on flavored yogurts is relatively limited in the context of Liubao tea, a tea with a rich cultural heritage. Developing a new type of tea yogurt using modern Liubao tea as the main raw material can not only expand the scope of Liubao tea deep processing, but also have great economic benefits. Summary of the Invention

[0006] The present application provides a Liubao tea yogurt and a preparation method thereof, aiming to develop a new type of Liubao tea yogurt, which perfectly combines the unique aroma of Liubao tea with the mellowness of yogurt, and stimulates the unique Liubao tea flavor by adding specific microbial fermentation agents, while also retaining the nutritional value and health care function of the yogurt itself.

[0007] In order to achieve the above objectives, this application adopts the following technical solutions.

[0008] In a first aspect of the present application, a method for preparing Liubao tea yogurt is provided, comprising:

[0009] Liubao tea is added to milk for extraction, and after the extraction is completed, tea residue is removed, and white sugar is added and stirred to dissolve to obtain an emulsion;

[0010] adding fermentation bacteria to the emulsion, stirring evenly, and then placing the emulsion in a biochemical incubator for constant temperature fermentation to obtain crude tea yogurt;

[0011] The crude tea yogurt is refrigerated and then ripened to obtain a finished Liubao tea yogurt product.

[0012] Preferably, the fermentation bacteria is a mixed bacteria of Streptococcus thermophilus and Lactobacillus bulgaricus in a ratio of 1:1.

[0013] Preferably, the extraction temperature is 90° C. and the extraction time is 15 minutes.

[0014] Preferably, the temperature of the refrigerated post-ripening is 0-4°C and the time is 24 hours.

[0015] Preferably, the amount of Liubao tea added is 1.5-2.5 wt % of the amount of milk used.

[0016] Preferably, the amount of added white sugar is 6.5-7.5wt% of the amount of milk.

[0017] Preferably, the amount of fermentation bacteria added is 1.4-1.8 wt% of the amount of milk used.

[0018] Preferably, the constant temperature fermentation time is 7 to 8 hours, and the fermentation temperature is 42°C.

[0019] Preferably, the amount of Liubao tea added is 2wt% of the amount of milk; the amount of white sugar added is 7wt% of the amount of milk; the amount of fermentation bacteria added is 1.6wt% of the amount of milk; the constant temperature fermentation time is 7.5h, and the fermentation temperature is 42°C.

[0020] The second aspect of the present application provides Liubao tea yogurt prepared by the above preparation method.

[0021] Compared with the prior art, the present invention has the following advantages:

[0022] The preparation method of the present application perfectly combines the unique aroma of Liubao tea with the mellowness of yogurt. By adding a specific microbial fermentation agent, the unique Liubao tea flavor is stimulated, while also retaining the nutritional value and health functions of the yogurt itself. The Liubao tea yogurt prepared in the present application not only satisfies the enjoyment of the taste buds, but also remains nutritious and healthy. DETAILED DESCRIPTION

[0023] The following will be combined with the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0024] In the following description of this embodiment, the terms "include", "comprising", "having" and "containing" are open-ended terms, meaning including but not limited to.

[0025] In the following description of this embodiment, the term "and / or" is used to describe the association relationship between associated objects, indicating that three possible relationships exist. For example, A and / or B can represent: A exists alone, B exists alone, and both A and B exist. A and B can be singular or plural. The character " / " generally indicates that the associated objects are in an "or" relationship.

[0026] In the following description of this embodiment, the term "at least one" refers to one or more, and "plurality" refers to two or more. "At least one of the following" or similar expressions refers to any combination of these items, including any combination of single items or plural items. For example, "at least one of a, b, or c", or "at least one of a, b, and c" can all represent: a, b, c, ab (i.e., a and b), ac, bc, or abc, where a, b, and c can be single or multiple.

[0027] The terms used in the embodiments of the present application are only for the purpose of describing specific embodiments and are not intended to limit the present application. The singular forms "a", "an" and "the" used in the embodiments of the present application and the appended claims are also intended to include plural forms unless the context clearly indicates otherwise.

[0028] Those skilled in the art should understand that in the following description of the embodiments of the present application, the order of serial numbers does not mean the order of execution, some or all of the steps can be executed in parallel or sequentially, and the execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of the present application.

[0029] It will be understood by those skilled in the art that the numerical ranges in the examples of the present application are to be understood as specifically disclosing each intermediate value between the upper and lower limits of the range. Each smaller range between any intermediate value within a stated value or stated range and any other stated value or intermediate value within the stated range is also included in the present application. The upper and lower limits of these smaller ranges may independently be included or excluded in the range.

[0030] Unless otherwise indicated, the technical / scientific terms used herein have the same meanings as those commonly understood by those skilled in the art to which this application belongs. Although this application describes only preferred methods and materials, any methods and materials similar or equivalent to those described herein may also be used in the implementation or testing of this application. All documents mentioned in this specification are incorporated by reference to disclose and describe the methods and / or materials related to the documents. In the event of any conflict with any incorporated document, the content of this specification shall prevail.

[0031] In a first aspect, the present application provides a method for preparing Liubao tea yogurt, comprising:

[0032] Liubao tea is added to milk for extraction, and after the extraction is completed, tea residue is removed, and white sugar is added and stirred to dissolve to obtain an emulsion;

[0033] In the present application, Liubao tea is preferably washed twice with 100°C boiling water and then added to milk for extraction, thereby fully extracting the tea flavor. The extraction temperature is 90°C and the extraction time is 15 minutes. After extraction, the tea residue is removed by centrifugation or filtration, and white sugar is added and stirred until dissolved to obtain an emulsion. The emulsion is cooled to 42°C for inoculation.

[0034] adding fermentation bacteria to the emulsion, stirring evenly, and then placing the emulsion in a biochemical incubator for constant temperature fermentation to obtain crude tea yogurt;

[0035] In the present application, the fermentation bacteria is a mixed bacteria of thermophilic Streptococcus and bulgaricus Lactobacillus in a ratio of 1:1; the constant temperature fermentation temperature is 42°C.

[0036] The crude tea yogurt is refrigerated and then ripened to obtain a finished Liubao tea yogurt product.

[0037] The yogurt texture has solidified after fermentation, but its flavor and taste have not reached the appropriate level. It must be refrigerated at 0-4℃ for 24 hours to complete the flavor transformation.

[0038] In the present application, the amount of Liubao tea added directly affects the sensory quality and acidity of the product. If the amount of tea added is low, the tea flavor is weak and the sensory score is low; as the amount of tea added increases, the sensory score of the yogurt first increases and then decreases; this is because when the amount of tea added is too high, the color of the yogurt deepens and inhibits the growth and metabolism of lactic acid bacteria, resulting in a significant decrease in sensory quality and acidity, that is, the greater the amount of tea added, the weaker the sour taste of the yogurt. The present application preferably adds Liubao tea in an amount of 1.5 to 2.5 wt% of the amount of milk used. Within this range, the color of the Liubao tea yogurt is uniform, the Liubao tea aroma is pleasant, and the tea aroma and milk aroma are properly blended.

[0039] In this application, the amount of added white sugar affects the quality and acidity of the yogurt. The more sugar, the lower the acidity. As the amount of sugar increases, the sensory score of the yogurt first increases and then decreases. The acidity is inversely proportional to the amount of sugar added. The increase in sugar neutralizes the sourness of the yogurt. The appropriate amount of sugar added can inhibit the acid production of the starter, and can make the yogurt have a moderate sweet and sour flavor with a delicate taste. In this application, the preferred amount of white sugar added is 6.5-7.5wt% of the amount of milk used.

[0040] In this application, the amount of fermentation bacteria added is directly related to the quality and acidity of the yogurt. As the amount of bacteria increases, the sensory score and acidity of the yogurt first increase and then decrease. This is because adding too much bacteria interferes with the growth and metabolism of lactic acid bacteria. An increasing number of live bacteria leads to a decrease in lactic acid production and a decrease in acidity. The preferred amount of fermentation bacteria added in this application is 1.4-1.8wt% of the amount of milk used. At this point, the yogurt curds are uniform and firm, with a smooth texture and a sweet and sour taste.

[0041] In the present application, the fermentation time directly affects the taste and texture of the yogurt. If the fermentation time is too long, the lactic acid bacteria will over-multiply and produce excessive acid, resulting in a product that is too sour; and too much acidic substance will destroy the unique colloidal structure that has been formed in the yogurt, and the colloidal substance originally used to maintain the structure will begin to decompose, causing the water in the yogurt to escape and form the so-called whey, which makes the yogurt texture thin, unstable, and even stratification. If the fermentation time is too short, the acid production is insufficient. Although lactic acid bacteria can grow rapidly and produce a small amount of acid, this acidity is not enough to form a good colloidal structure. Therefore, the texture of the yogurt is often loose, and there may be more bubbles or milk protein particles that are not completely fixed inside, resulting in an uneven appearance of the yogurt and a lack of proper viscosity and coagulation, which ultimately leads to a decrease in sensory quality. In the present application, the preferred fermentation time is 7 to 8 hours, and the fermentation temperature is 42°C.

[0042] The present application found that when the amount of Liubao tea added is 2wt% of the amount of milk, the amount of white sugar added is 7wt% of the amount of milk, the amount of fermentation bacteria added is 1.6wt% of the amount of milk, the constant temperature fermentation time is 7.5h, and the fermentation temperature is 42°C, the Liubao tea yogurt prepared under these process conditions has a light milk tea color and a uniform color, a moderate fusion of Liubao tea aroma and yogurt flavor, no other odor, a sweet and sour taste, a uniform and firm curd, a smooth and delicate texture, and no whey precipitation; the overall evaluation is that it has both the unique flavor of yogurt and the charm of Liubao tea.

[0043] The Liubao tea yogurt prepared in the present application perfectly combines the unique aroma of Liubao tea with the mellowness of yogurt, which not only satisfies the enjoyment of taste buds but also remains nutritious and healthy. It can not only expand the deep processing field of Liubao tea, but also has great economic benefits.

[0044] The present application is further described below through specific examples.

[0045] Example 1

[0046] The milk content is 150 mL, the tea content is 1.5%, the white sugar content is 6.5%, the fermentation time is 7 h, and the fermentation bacteria content is 1.6 wt%;

[0047] The preparation method is:

[0048] Liubao tea is added to milk for extraction, and after the extraction is completed, tea residue is removed, and white sugar is added and stirred to dissolve to obtain an emulsion;

[0049] adding fermentation bacteria to the emulsion, stirring evenly, and then placing the emulsion in a biochemical incubator for constant temperature fermentation to obtain crude tea yogurt;

[0050] The crude tea yogurt is refrigerated and then ripened to obtain a finished Liubao tea yogurt product.

[0051] Example 2

[0052] The milk content is 150 mL, the tea dosage is 1.5%, the sugar addition amount is 7%, the fermentation time is 8 h, and the fermentation bacteria addition amount is 1.6 wt%;

[0053] The preparation method of Example 2 is the same as that of Example 1.

[0054] Example 3

[0055] The milk content is 150 mL, the tea dosage is 1.5%, the white sugar addition amount is 7.5%, the fermentation time is 7.5 h, and the fermentation bacteria addition amount is 1.6 wt%;

[0056] The preparation method of Example 3 is the same as that of Example 1.

[0057] Example 4

[0058] The milk content is 150 mL, the tea dosage is 2%, the sugar addition amount is 6.5%, the fermentation time is 8 h, and the fermentation bacteria addition amount is 1.6 wt%;

[0059] The preparation method of Example 4 is the same as that of Example 1.

[0060] Example 5

[0061] The milk content is 150 mL, the tea dosage is 2%, the sugar addition amount is 7%, the fermentation time is 7.5 h, and the fermentation strain addition amount is 1.6 wt%;

[0062] The preparation method of Example 5 is the same as that of Example 1.

[0063] Example 6

[0064] The amount of milk is 150mL, the amount of tea added is 2%, the amount of white sugar added is 7.5%, the fermentation time is 7h, and the amount of fermentation bacteria added is 1.6wt%;

[0065] The preparation method of Example 6 is the same as that of Example 1.

[0066] Example 7

[0067] The milk content is 150 mL, the tea dosage is 2.5%, the sugar dosage is 6.5%, the fermentation time is 7.5 h, and the fermentation bacteria dosage is 1.6 wt%;

[0068] The preparation method of Example 7 is the same as that of Example 1.

[0069] Example 8

[0070] The milk content is 150 mL, the tea dosage is 2.5%, the sugar addition amount is 7%, the fermentation time is 7 h, and the fermentation bacteria addition amount is 1.6 wt%;

[0071] The preparation method of Example 8 is the same as that of Example 1.

[0072] Example 9

[0073] The milk content is 150 mL, the tea content is 2.5%, the sugar content is 7.5%, the fermentation time is 8 h, and the fermentation bacteria content is 1.6 wt%;

[0074] The preparation method of Example 9 is the same as that of Example 1.

[0075] A scoring table was developed based on the sensory standards for fermented milk (GB 19302-2010) to conduct a sensory evaluation of the Liubao Tea yogurt prepared in this application. To ensure objectivity and accuracy, eight evaluators with sensory experience were invited to evaluate the yogurt. The evaluation criteria and their weightings were yogurt color (20%), aroma (20%), flavor (30%), and texture (30%). The sensory evaluation and scoring were based on these four aspects of the yogurt. The specific sensory standards are shown in Table 1.

[0076] Table 1 Sensory evaluation standards for Liubao tea yogurt

[0077]

[0078] The results of the sensory evaluation of the finished Liubao tea yogurts prepared in Examples 1-9 are shown in Table 2.

[0079] Table 2 Sensory evaluation results of Liubao tea yogurt products prepared in Examples 1-9

[0080]

[0081]

[0082] The Liubao tea yogurt prepared in Example 5 had the best sensory evaluation results. Its color was light milk tea color and uniform. The Liubao tea aroma and yogurt flavor were moderately blended, no other odors appeared, the taste was sweet and sour, the curd was uniform and firm, the texture was smooth and delicate, and there was no whey precipitation. The overall evaluation showed that it had both the unique flavor of yogurt and the charm of Liubao tea.

[0083] The Liubao tea yogurt prepared in Example 5 was subjected to an optimal drinking period test. The method is as follows: the optimal drinking period of the Liubao tea yogurt is determined by changes in acidity and sensory quality during storage at 0-4°C. The evaluation results are shown in Table 3.

[0084] Table 3 Test results of the best drinking period of Liubao tea yogurt

[0085]

[0086] As shown in Table 3, the sensory score of the yogurt on the first day of storage was significantly higher than that of other samples, with the highest score being 92.10±1.41a points, while the titratable acidity was significantly lower than that of other samples, at 81.00±0.66h°T. Within 7 days, the sensory quality of the yogurt was good, with the sensory score being above 81.60 points and the acidity being within 90.13°T. During this storage period, the yogurt product showed a uniform color, obvious tea and milk aroma, moderate sweet and sour taste, and a smooth texture. The quality is delicate and smooth; when it is 9-11 days, the sensory score is significantly lower than 80.00 points, the acidity is significantly higher than 90.00°T, the yogurt begins to become obviously sour, and whey begins to precipitate with storage time; and when it is 13-15 days, the sensory score is significantly lower than 70.00 points, the acidity gradually increases, significantly higher than 95.00°T, the taste is sour, the yogurt curd begins to become uneven, and some whey gradually precipitates, resulting in a gradual decrease in sensory quality and a gradual increase in acidity.

[0087] During the 15-day storage period, storage time and acidity showed a positive correlation, while sensory scores showed the opposite. As storage time increased, the sensory scores gradually decreased, while acidity gradually increased. This was primarily due to continued growth and metabolism of lactic acid bacteria, which increased the production of acidic substances, causing the product to become sour, leading to a lower sensory score. Based on the above conclusions regarding the sensory quality and acidity of Liubao Tea yogurt within 7 days, its optimal drinking period is determined to be within 7 days.

[0088] The Liubao tea yogurt prepared in Example 5 was subjected to physical and chemical index tests, including protein test, sugar content test, pH test and acidity test. The test results are shown in Table 4.

[0089] Among them, protein determination is carried out in accordance with GB 5009.5-2016 "National Food Safety Standard - Determination of Protein in Foods"; sugar content determination is carried out in accordance with GB 5009.8-2023 "National Food Safety Standard - Determination of Fructose, Glucose, Sucrose, Maltose and Lactose in Foods"; pH determination is carried out in accordance with GB 5009.237-2016 "National Food Safety Standard - Determination of pH Value of Foods"; acidity determination is carried out in accordance with GB 5009.239-2016 "National Food Safety Standard - Determination of Acidity in Foods".

[0090] Table 4 Results of physical and chemical index determination of Liubao tea yogurt (Table 3-13)

[0091] Physical and chemical composition Protein g / 100g Reducing sugar g / 100g pH Acidity °T average value 3.94±0.11 6.76±0.08 4.05±0.00 81.00±0.66

[0092] The test results show that the physical and chemical index test results of the Liubao tea yogurt prepared in Example 5 are 3.94g / 100g protein, 6.76g / 100g reducing sugar, pH value 4.05, and acidity 81.00°T, all of which meet the standards of T / WSJD 12-2020 "Plant Protein Beverage Plant Yogurt".

[0093] Although this specification has been used to fully describe the present application using general descriptions and specific embodiments, it is obvious to those skilled in the art that modifications or improvements may be made based on the present application. Therefore, such modifications or improvements made without departing from the spirit of the present application are within the scope of protection claimed in this application.

Claims

1. A method for preparing Liubao tea yogurt, characterized in that: include: Liubao tea is added to milk for extraction, and after the extraction is completed, tea residue is removed, and white sugar is added and stirred to dissolve to obtain an emulsion; adding fermentation bacteria to the emulsion, stirring evenly, and then placing the emulsion in a biochemical incubator for constant temperature fermentation to obtain crude tea yogurt; The crude tea yogurt is refrigerated and then ripened to obtain a finished Liubao tea yogurt product.

2. The preparation method according to claim 1, characterized in that The fermentation bacteria are a mixed bacteria of thermophilic streptococcus and bulgaricus lactobacillus in a ratio of 1:

1.

3. The preparation method according to claim 1, characterized in that The extraction temperature is 90° C. and the extraction time is 15 minutes.

4. The preparation method according to claim 1, characterized in that The temperature of the refrigerated post-ripening is 0-4°C and the time is 24 hours.

5. The preparation method according to claim 1, characterized in that The added amount of Liubao tea is 1.5-2.5wt% of the amount of milk.

6. The preparation method according to claim 1, characterized in that The amount of white sugar added is 6.5-7.5wt% of the milk amount.

7. The preparation method according to claim 1, characterized in that The added amount of the fermentation bacteria is 1.4-1.8 wt% of the amount of milk used.

8. The preparation method according to claim 1, characterized in that The constant temperature fermentation time is 7 to 8 hours, and the fermentation temperature is 42°C.

9. The preparation method according to claim 1, characterized in that The amount of Liubao tea added is 2wt% of the amount of milk; The amount of white sugar added is 7wt% of the amount of milk; The amount of the fermentation bacteria added is 1.6 wt% of the amount of milk used; The constant temperature fermentation time is 7.5 hours, and the fermentation temperature is 42°C.

10. Liubao tea yogurt prepared by the preparation method according to any one of claims 1 to 9.

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