A kind of yogurt and its preparation method

Abstract

The present invention relates to the field of food, and particularly to a yogurt and a preparation method thereof. The yogurt comprises the following raw materials in parts by mass: 1000 parts of raw milk and 15 - 20 parts of a stabilizer. The stabilizer comprises a first stabilizer and a second stabilizer. The first stabilizer comprises citrus fiber, inulin and starch. The second stabilizer comprises sodium hyaluronate and prickly pear cactus powder. The present invention utilizes special types and ratios of stabilizers, thereby achieving high product stability on the basis of overall reducing the amount of stabilizers, without whey separation during the shelf life, having a stable tissue state and good taste. In addition, sodium hyaluronate also has a certain effect of beautifying and nourishing the skin. The yogurt obtained by the present invention is more popular among consumers.

Description

Technical Field

[0001] The present invention relates to the field of food, and particularly to a yogurt and a preparation method thereof. Background Art

[0002] Yogurt is a dairy product fermented from milk and is rich in protein, calcium, and vitamins. Yogurt has a delicate texture, a sour and sweet taste, and a variety of varieties, so it is loved by the majority of consumers. However, in the current market, many yogurts have been made into "desserts" full of sugar and various processed fruits.

[0003] Nowadays, consumers pay more and more attention to food quality, including basic food safety and more functional requirements, such as improving body immunity and achieving beauty effects. Therefore, when choosing dairy products, there is an increasing demand for low sugar content and functional effects. As a result, 0-sucrose yogurt has emerged. However, due to the lack of sucrose addition in the 0-sucrose yogurt product, the solid content is low, and problems such as product water separation and astringent taste are likely to occur. Summary of the Invention

[0004] In view of the deficiencies of the prior art, the present invention provides a yogurt and a preparation method thereof.

[0005] The present invention provides a yogurt, which comprises the following raw materials in parts by mass: 1000 parts of raw milk and 15 - 20 parts of a stabilizer. The stabilizer comprises a first stabilizer and a second stabilizer. The first stabilizer comprises citrus fiber, inulin, and starch, and the second stabilizer comprises sodium hyaluronate and prickly pear cactus powder.

[0006] In the prior art, the stabilizers used in yogurt products are generally monomer colloids such as starch, pectin, agar, gellan gum, or a combination thereof. However, on the one hand, it is difficult to balance the stability effect and the texture of the taste when using these stabilizers. On the other hand, because consumers always fear "colloids", the products are not popular. The present invention uses a special type and ratio of stabilizers. Among them, a small amount of starch plays a role in building a stable network system. Citrus fiber and inulin replace part of the starch to improve the stability of the network system. Sodium hyaluronate and prickly pear cactus powder can play a synergistic water retention role with starch-based stabilizers, so as to achieve high product stability on the basis of generally reducing the dosage of "colloids", without whey separation during the shelf life, having a stable tissue state and a good taste. In addition, sodium hyaluronate also has a certain beauty and skin care effect, and the yogurt obtained by the present invention is more popular among consumers.

[0007] It should be noted that the raw milk described in the present invention is an emulsion that can be used as a raw material for yogurt fermentation, including one or more of raw milk (fresh cow and sheep milk), pasteurized milk (processed by pasteurization), ambient temperature milk (processed by ultra-high temperature instantaneous treatment), reconstituted milk (blended with milk powder), and recombined milk (processed from skim milk powder, water, and anhydrous butter).

[0008] For the yogurt provided by the present invention, the mass ratio of the first stabilizer to the second stabilizer is (16 - 20):(1 - 2).

[0009] For the yogurt provided by the present invention, in the first stabilizer, the mass ratio of citrus fiber, inulin, and starch is 3 - 4∶1 - 2∶4 - 8, more preferably 3∶2∶8.

[0010] For the yogurt provided by the present invention, in the second stabilizer, the mass ratio of sodium hyaluronate to prickly pear cactus powder is 0.15 - 0.2∶1 - 2, more preferably 0.2∶1.3.

[0011] For the yogurt provided by the present invention, the raw materials further include strains and lactase, and the lactase is aseptically added online after adding the strains.

[0012] Furthermore, the addition amount of the lactase is 1 ± 0.2 g / L. The lactase is preferably lactase NolaFit.

[0013] In the prior art, white granulated sugar and sugar substitutes are usually used to increase the sweetness of yogurt. The present invention uses lactase to decompose lactose to increase the sweetness of yogurt. Principle analysis: The strains consume part of the lactose and decompose it into lactic acid; lactase hydrolyzes lactose through β-galactosidase to become two monosaccharides. After yogurt fermentation, acid is directly produced. Without adding sugar, it will be more sour; after lactase enzymatic hydrolysis, lactose becomes galactose and glucose, and the combined sweetness of the two is higher than that of lactose, so it tastes sweeter. It is selected to add lactase immediately after the strains. Lactase still has activity at a suitable temperature of 36 - 44°C and acidic conditions, and continues to efficiently enzymatically hydrolyze lactose in an environment where the fermentation pH value continuously decreases, making the lactose content less than 0.5%, increasing the sweetness equivalent to about 0.7% of sucrose to replace 1% - 1.5% of sugar alcohols, that is, saving the addition amount of 1.0% - 1.5% of sugar alcohols (maltitol, erythritol), and the cost can be saved by 100 - 150 yuan / T.

[0014] The strains of the present invention are one or more of Lactobacillus bulgaricus, Streptococcus thermophilus, Lactococcus lactis subsp. lactis, Lactococcus lactis subsp. cremoris, and Lactobacillus paracasei.

[0015] For the yogurt provided by the present invention, the raw materials further include whey protein powder, and its mass fraction is 1 - 5 parts.

[0016] The present invention also provides a preparation method for the above yogurt.

[0017] The preparation method provided by the present invention includes the following steps:

[0018] Mix the raw milk with the raw materials except the strains, and perform degassing, homogenization, sterilization, and cooling to obtain a fermentation substrate;

[0019] Inoculate the fermentation substrate with strains, add lactase, ferment until the acidity reaches the fermentation end point, demulsify, perform secondary sterilization, cool, and fill.

[0020] As described above, the appropriate feeding time of lactase is crucial. After inoculating the strains and lactase, it can quickly decompose lactose to produce a sweet taste, achieving the effect of enhancing the sweetness of yogurt, and can achieve zero sucrose and moderate sweetness.

[0021] According to the preparation method provided by the present invention, during the mixing process of raw milk and the remaining raw materials, high-speed dynamic mixing is adopted, and raw materials with relatively low moisture content such as whey protein powder and starch are added last to improve the dispersion effect of the raw materials and reduce the generation of bubbles.

[0022] The process of mixing raw milk and the remaining raw materials is called material preparation. This process adopts high-speed dynamic mixing, but does not perform milk circulation heating. The liquid only passes through a shear pump once, reducing the shear on the product stabilizer and improving the product stability. During this process, it is preferably to add starch last, so that the damage to it is extremely small, and the starch raw material can quickly absorb water and swell. When the raw materials include substances such as whey protein powder, these substances are also added later. In addition, sodium hyaluronate and Opuntia ficus-indica powder are also preferably added later during the feeding process to avoid irreversible effects on the raw materials caused by the shear head of the high-speed mixer. Use appropriate shear rate and shear temperature to make the raw materials fully absorb the water in the milk during the dispersion process, achieving the water retention effect, forming a synergistic water retention effect with starch, and improving the stability of yogurt indicators without attenuation during the shelf life.

[0023] According to the preparation method provided by the present invention, the temperature of the degassing is controlled at 60±5°C.

[0024] Generally, a degassing system is not used in the production process of yogurt. However, the present invention has found through research that a large amount of air bubbles are mixed in during the high-speed dispersion process of the raw materials in the raw milk, which has a great relationship with the stability and sensory effect of the product during the shelf life. After adding the degassing step in the present invention, the product quality has been greatly improved, and the present invention controls the degassing temperature at about 60°C, which can protect the starch-based stabilizer and improve the stability.

[0025] In addition, it should be noted that since the viscosity of the liquid in the present invention is relatively high, a degassing tank that increases the heat exchange area and efficiency can be used to remove the gas contained in the high-viscosity liquid, making the product more stable and extending the shelf life of the product.

[0026] According to the preparation method provided by the present invention, the sterilization adopts ultra-high temperature sterilization, and the temperature is 121-128°C; the secondary sterilization adopts pasteurization, and the temperature is 70-80°C.

[0027] In the prior art, refrigerated yogurt is generally sterilized at 95°C for 300 s, and room-temperature yogurt is sterilized at 133 - 139°C for 4 - 8 s. The degree of thermal damage to the product is large and the stability is poor. The present invention uses a sterilization combination between high temperature and low temperature to reduce the degree of thermal damage to the product and improve the product stability. Moreover, it is necessary to first use ultra-high temperature sterilization and then use pasteurization for the secondary sterilization, and the order of the two cannot be reversed, otherwise the protein in the product is unstable and the granular and sandy tastes are obvious.

[0028] According to the preparation method provided by the present invention, the total pressure of the homogenization is controlled at 100 - 150 bar, wherein the primary pressure is 75 - 115 bar and the secondary pressure is 25 - 35 bar.

[0029] It should be noted that in the above preparation method, the steps not specifically described in the present invention are carried out according to the conventional steps for preparing yogurt known to those skilled in the art. For example, the fermentation temperature is usually 42 - 45°C; the fermentation end point is a pH of about 4.3. The instruments and equipment used in each step are conventional equipment if not specifically described. For example, homogenization is carried out using a homogenizer, fermentation is carried out in a fermentation tank, and sterilization is carried out in a sterilizer.

[0030] The present invention has the following beneficial effects:

[0031] The present invention provides a yogurt and its preparation method, which uses special types and ratios of stabilizers. Among them, a small amount of starch plays a role in building a stable network system, citrus fiber and inulin replace part of the starch to improve the stability of the network system, and sodium hyaluronate and prickly pear powder can play a synergistic water retention role with starch-based stabilizers, so as to achieve high product stability on the basis of overall reducing the amount of stabilizers, without whey separation during the shelf life, having a stable tissue state and good taste. In addition, sodium hyaluronate also has certain beauty and skin care effects, and the yogurt obtained by the present invention is more popular among consumers. Specific Embodiments

[0032] The following examples are used to illustrate the present invention, but are not used to limit the scope of the present invention.

[0033] The reagents and equipment involved in the following examples can be obtained commercially if not specifically mentioned.

[0034] The methods involved in the following examples can be implemented by conventional methods in the art if not specifically described.

[0035] Example 1

[0036] This example provides a yogurt, and its preparation method is as follows:

[0037] The milk is heated cyclically to 45°C and directly fed into the batching tank after the heating is completed. The remaining raw materials are added (based on 1000 parts by weight of milk): 17.5 parts by weight of starch and its substitutes (where the ratio of citrus fiber, inulin, and starch is 3:2:8), 3 parts by weight of whey protein powder, 0.2 parts by weight of sodium hyaluronate, and 1.3 parts by weight of prickly pear cactus powder. During the addition process, high-speed dynamic mixing is used, and the milk is not heated cyclically to reduce the shear of the product stabilizer.

[0038] After the feeding is completed, the product is degassed at a temperature of 60°C, then homogenized with a primary pressure of 110 bar and a secondary pressure of 30 bar. After homogenization, sterilization is carried out at a temperature of 121°C for 6 s.

[0039] The liquid material is cooled to 40°C and the strains are added. The strains are Lactobacillus bulgaricus, Streptococcus thermophilus (the addition amount of the mixed strains is 100 U / ton), and Lactobacillus paracasei (the addition amount is 100 U / ton). The lactase Nola Fit (the addition amount is 1 g / L) is continuously mixed with the base material at 40°C using the aseptic online addition system of the strains, and lactose is decomposed during the fermentation for 4 - 6 hours.

[0040] Fermentation continues in the fermentation tank. When the pH value reaches 4.3, demulsification is carried out with a stirring speed of 35 revolutions per minute for 5 minutes. After the stirring is completed, it is quickly cooled to 20°C to obtain the cooled fermented milk. The cooled fermented milk is pasteurized at a temperature of 75°C for 25 s, cooled to 25°C, and then stored in an aseptic tank and filled.

[0041] Example 2

[0042] This example provides a kind of yogurt, and its preparation method is as follows:

[0043] The milk is heated cyclically to 45°C and directly fed into the batching tank after the heating is completed. The remaining raw materials are added (based on 1000 parts by weight of milk): 18.5 parts by weight of starch and its substitutes (where the ratio of citrus fiber, inulin, and starch is 3:2:8), 4 parts by weight of whey protein powder, 0.2 parts by weight of sodium hyaluronate, and 1.3 parts by weight of prickly pear cactus powder. During the addition process of the raw materials, high-speed dynamic mixing is used, and the milk is not heated cyclically to reduce the shear of the product stabilizer.

[0044] After the feeding is completed, the product is degassed at a temperature of 65°C, then homogenized with a primary pressure of 110 bar and a secondary pressure of 30 bar. After homogenization, sterilization is carried out at a temperature of 125°C for 6 s.

[0045] The liquid material is cooled to 43°C and the strains are added. The strains are Lactobacillus bulgaricus, Streptococcus thermophilus (the addition amount of the mixed strains is 100 U / ton), and Lactobacillus paracasei (the addition amount is 100 U / ton). Using the aseptic online strain addition system, lactase Nola Fit (the addition amount is 1 g / L) is continuously mixed with the base material at 40°C, and lactose is decomposed during the 4 - 6 hours of fermentation.

[0046] Continue to ferment in the fermenter. When the pH value reaches 4.3, break the emulsion and stir. The stirring speed is 35 revolutions per minute, and stir for 2 minutes. After stirring is completed, quickly cool in the fermenter to 20°C to obtain the cooled fermented milk. The cooled fermented milk is pasteurized. The pasteurization temperature is 75°C and the time is 25 s. After cooling to 25°C, it enters the aseptic tank for storage and filling.

[0047] Example 3

[0048] This example provides a kind of yogurt, and its preparation method is as follows:

[0049] The milk is heated in a cycle to 45°C. After the heating is completed, it is directly pumped into the batching tank, and the remaining raw materials are added (based on 1000 parts by weight of milk as the measurement benchmark): 17.5 parts by weight of starch and its substitutes (where the ratio of citrus fiber, inulin, and starch is 3:2:8), 3 parts by weight of whey protein powder, 0.2 parts by weight of sodium hyaluronate, and 1.3 parts by weight of Opuntia ficus-indica powder. During the addition process, high-speed dynamic mixing is adopted, and the milk is not heated in a cycle to reduce the shear of the product stabilizer, thereby improving the product stability.

[0050] After the feeding is completed, the product is degassed at a temperature of 60°C, and then homogenized. The homogenization pressure is 110 bar for the first stage and 30 bar for the second stage. After homogenization is completed, it is sterilized. The sterilization temperature is 128°C and the sterilization time is 4 s.

[0051] The liquid material is cooled to 40°C and the strains are added. The strains are Lactobacillus bulgaricus, Streptococcus thermophilus (the addition amount of the mixed strains is 100 U / ton), and Lactobacillus paracasei (the addition amount is 100 U / ton). Using the aseptic online strain addition system, lactase Nola Fit (the addition amount is 1 g / L) is continuously mixed with the base material at 40°C, and lactose is decomposed during the 4 - 6 hours of fermentation.

[0052] Continue to ferment in the fermenter. When the pH value reaches 4.3, break the emulsion and stir. The stirring speed is 35 revolutions per minute, and stir for 5 minutes. After stirring is completed, quickly cool in the fermenter. The cooled fermented milk is pasteurized. The pasteurization temperature is 75°C and the time is 25 s. After cooling to 25°C, it enters the aseptic tank for storage and filling.

[0053] Comparative Example 1

[0054] This comparative example provides a yogurt, which is different from that of Example 1 in that the remaining raw materials (based on 1000 parts by weight of milk): 17.5 parts by weight of starch and its substitutes (where the ratio of citrus fiber, inulin, and starch is 3:1:9), 3 parts by weight of whey protein powder, 0.2 parts by weight of sodium hyaluronate, and 1.3 parts by weight of prickly pear cactus powder.

[0055] Comparative Example 2

[0056] This comparative example provides a yogurt, which is different from that of Example 1 in that the remaining raw materials (based on 1000 parts by weight of milk): 20.5 parts by weight of starch and its substitutes (where the ratio of citrus fiber, inulin, and starch is 3:2:10), 4 parts by weight of whey protein powder, 0.2 parts by weight of sodium hyaluronate, and 1.3 parts by weight of prickly pear cactus powder.

[0057] Comparative Example 3

[0058] This comparative example provides a yogurt, which is different from that of Example 1 in that the remaining raw materials (based on 1000 parts by weight of milk): 17.5 parts by weight of starch and its substitutes (where the ratio of citrus fiber, inulin, and starch is 3:2:8), 10 parts by weight of whey protein powder, 0.2 parts by weight of sodium hyaluronate, and 1.3 parts by weight of prickly pear cactus powder.

[0059] Comparative Example 4

[0060] This comparative example provides a yogurt, which is different from that of Example 1 in that the remaining raw materials (based on 1000 parts by weight of milk): 19 parts by weight of starch and its substitutes (where the ratio of citrus fiber, inulin, and starch is 3:2:8), 3 parts by weight of whey protein powder.

[0061] Comparative Example 5

[0062] This comparative example provides a yogurt, which is different from that of Example 1 in that the remaining raw materials (based on 1000 parts by weight of milk): 17.5 parts by weight of starch and its substitutes (where the ratio of citrus fiber, inulin, and starch is 3:2:8), 3 parts by weight of whey protein powder, 0.8 parts by weight of pectin, and 1.2 parts by weight of agar.

[0063] Comparative Example 6

[0064] This comparative example provides a yogurt, which is different from that of Example 1 in that lactase Nola Fit is replaced with ordinary lactase (enzymatically hydrolyzing lactose under neutral conditions of pH = 5.5 - 7.5).

[0065] Comparative Example 7

[0066] This comparative example provides a yogurt, which is different from that of Example 1 in that the inlet temperature of the degassing tank is 45°C.

[0067] Comparative Example 8

[0068] This comparative example provides a kind of yogurt, the difference from Example 1 is that the primary pressure of the homogenizer is 80 bar and the secondary pressure is 20 bar.

[0069] Comparative Example 9

[0070] This comparative example provides a kind of yogurt, the difference from Example 1 is that the ultra-pasteurization temperature for the first sterilization is 133 °C.

[0071] Comparative Example 10

[0072] This comparative example provides a kind of yogurt, the difference from Example 1 is that the aseptic on-line addition system for strains is not adopted, lactase Nola Fit is added at the tank mouth of the fermentation tank, and after 900 s of stirring and dispersion, the stirring is turned off to decompose lactose.

[0073] Performance Detection:

[0074] 1. Viscosity test

[0075] Using a rheometer, at 25 °C, the viscosity of the product (unit: mPa·s) was measured with the cc27 probe rising and falling at a speed of 75 times per second. The results are shown in Table 1.

[0076] Table 1

[0077] Just Prepared One Month Two Months Three Months Four Months Five Months Example 1 463.2 446.8 436.2 426.9 425.3 413.2 Example 2 455.8 416.3 414.2 413.6 435.4 422.6 Example 3 449.5 423.9 433.2 409.5 403.3 403.2 Comparative Example 1 444.2 415.2 372.6 361.2 288.4 255.2 Comparative Example 2 430.6 433.7 361.1 318.8 286.8 261.9 Comparative Example 3 448.3 426.5 409.6 335.2 233.6 227.3 Comparative Example 4 444.3 433.6 428.9 326.6 313.4 308.9 Comparative Example 5 426.3 385.2 366.4 305.6 288.4 255.3 Comparative Example 6 486 455 412 374.6 336.5 312.9 Comparative Example 7 408.6 386.5 363.6 335.2 333.6 327.3 Comparative Example 8 344.8 333.6 308.9 286.6 273.4 288.9 Comparative Example 9 486.3 365.2 346.4 345.6 338.4 335.3 Comparative Example 10 359.0 355.2 306.4 305.6 288.4 275.3

[0078] 2. Liking degree test

[0079] Twenty tasting personnel were randomly selected for the product liking degree test (also known as sensory evaluation). Among them, the liking degree test adopted the scoring method. The scoring method is a method of using numbers to score to evaluate products or product characteristics. Finally, the quality is determined according to the average score. The scoring rules are in the range of 0 - 10 points. 0 - 2 points are regarded as poor, 3 - 5 points are regarded as average, 6 - 8 points are regarded as good, and 9 - 10 points are regarded as excellent. The evaluation items include: color and luster, flavor, and taste. The test results are shown in Table 2.

[0080] Table 2

[0081] Just Prepared One Month Two Months Three Months Four Months Five Months Example 1 8 8 7 6 6 6 Example 2 8 8 7 7 6 6 Example 3 9 8 8 7 7 7 Comparative Example 1 8 7 7 5 5 5 Comparative Example 2 7 8 7 4 4 5 Comparative Example 3 7 7 6 5 5 5 Comparative Example 4 8 7 6 5 5 4 Comparative Example 5 8 8 6 4 5 5 Comparative Example 6 7 8 6 4 5 5 Comparative Example 7 8 7 6 4 4 5 Comparative Example 8 7 7 7 5 4 5 Comparative Example 9 7 6 6 5 4 4 Comparative Example 10 8 8 6 5 4 4

[0082] 3. Stability test

[0083] The product was placed in an environment of 38 °C for heat preservation observation. The results are shown in Table 3.

[0084] Table 3

[0085]

[0086]

[0087] 4. Microbiological examination

[0088] Table 4

[0089]

[0090] Although the present invention has been described in detail above with general descriptions and specific embodiments, modifications or improvements can be made thereto based on the present invention, which are obvious to those skilled in the art. Therefore, these modifications or improvements made without departing from the spirit of the present invention fall within the scope of protection of the present invention.

Claims

1. A kind of yogurt, characterized in that, It comprises raw materials in the following parts by mass: 1000 parts of raw milk and 15 - 20 parts of stabilizer. The stabilizer comprises a first stabilizer and a second stabilizer. The first stabilizer comprises citrus fiber, inulin and starch. The second stabilizer comprises sodium hyaluronate and prickly pear cactus powder; Among them, the mass ratio of the first stabilizer to the second stabilizer is (16 - 20):(1 - 2); Among them, in the first stabilizer, the mass ratio of citrus fiber, inulin and starch is 3 - 4:1 - 2:4 - 8; in the second stabilizer, the mass ratio of sodium hyaluronate and prickly pear cactus powder is 0.15 - 0.2:1 - 2.

2. The yogurt according to claim 1, characterized in that, In the first stabilizer, the mass ratio of citrus fiber, inulin and starch is 3:2:

8.

3. The yogurt according to claim 2, wherein In the second stabilizer, the mass ratio of sodium hyaluronate and prickly pear cactus powder is 0.2:1.

3.

4. The yogurt according to claim 1, characterized in that, The raw materials further comprise strains and lactase, and the lactase is added after adding the strains.

5. The yogurt according to any one of claims 1-4, characterized in that, The raw materials further comprise 1 - 5 parts of whey protein powder.

6. The method for preparing the yogurt according to any one of claims 1-5, characterized in that, It comprises the following steps: Mix the raw milk with the raw materials except the strains, and conduct degassing, homogenization, sterilization and cooling to obtain a fermentation substrate; Inoculate the strains into the fermentation substrate, add lactase, ferment until the acidity reaches the fermentation end point, break the emulsion, conduct secondary sterilization, cooling and filling.

7. The method for preparing yogurt according to claim 6, characterized in that, During the mixing of the raw milk and the other raw materials, high - speed dynamic mixing is adopted, and the starch is added last.

8. The preparation method of the yogurt according to claim 6, characterized in that, The temperature of the degassing is controlled at 60±5℃.

9. The method for preparing yogurt according to claim 6, characterized in that, The sterilization adopts ultra - high temperature sterilization, and the temperature is 121 - 128℃; The secondary sterilization adopts pasteurization, and the temperature is 70 - 80℃.

10. The preparation method of the yogurt according to claim 6, characterized in that, The total pressure of the homogenization is controlled at 100 - 150 bar, wherein the primary pressure is 75 - 115 bar and the secondary pressure is 25 - 35 bar.

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