Kefir fermented product and preparation method thereof

Abstract

The invention provides a Kefir fermentation product and a preparation method thereof, the raw materials of the Kefir fermentation product comprise a Kefir fermentation base material and fruit juice, the mass ratio of the Kefir fermentation base material to the fruit juice is (90-99): (1-10), and the total acid of the fruit juice is required to be greater than or equal to 1.0%; the Kefir fermentation product is prepared by a method at least comprising the following steps: mixing the Kefir fermentation base material and the fruit juice, and placing at 20-30 DEG C for 4-10 hours to obtain the Kefir fermentation product. The kefir fermentation product has a strong taste like a carbonated beverage.

Description

Technical Field

[0001] The present invention relates to a kefir fermented product, and particularly to a kefir fermented product and a preparation method thereof, belonging to the food field. Background Art

[0002] Kefir is a traditional fermented product, generally using cow milk or goat milk as raw materials, and using kefir grains as a fermenting agent to produce a fermented product containing gas CO 2 and an alcoholic flavor. Kefir fermented products are easy to digest, have certain health care effects, and have a unique kefir flavor and a carbonated drink-like tingling sensation, bringing consumers a "healthier and more interesting" consumption experience and being loved by the majority of consumers.

[0003] However, during the production process of existing kefir fermented products, the filling process will cause different degrees of loss of gas in the kefir fermented products, resulting in a significant weakening of the bubble texture of the products. Therefore, a kefir fermented product with a strong carbonated drink-like tingling sensation is expected to fill the relevant market gap. Summary of the Invention

[0004] The present invention provides a kefir fermented product with a strong carbonated drink-like tingling sensation.

[0005] The present invention also provides a preparation method of a kefir fermented product. The preparation method has a simple process and is convenient to operate. Through this preparation method, a kefir fermented product with a strong carbonated drink-like tingling sensation can be obtained.

[0006] The present invention provides a kefir fermented product, and the raw materials of the kefir fermented product include a kefir fermentation base material and fruit juice. The mass ratio of the kefir fermentation base material to the fruit juice is (90 - 99) : (1 - 10), wherein the total acid of the fruit juice ≥ 1.0%;

[0007] The kefir fermented product is prepared by at least the following method: after mixing the kefir fermentation base material and the fruit juice, it is placed at 20 - 30 °C for 4 - 10 h to obtain the kefir fermented product.

[0008] For the kefir fermented product as described above, the mass ratio of the kefir fermentation base material to the fruit juice is (92 - 98) : (2 - 8).

[0009] For the kefir fermented product as described above, after mixing the kefir fermentation base material and the fruit juice, it is placed at 25 - 30 °C for 6 h to obtain the kefir fermented product.

[0010] The kefir fermentation product as described above, wherein the fruit juice includes at least one of berry juice, stone fruit juice, melon juice, pome fruit juice, and hesperidium juice.

[0011] The kefir fermentation product as described above, wherein the fruit juice is prepared by a method that at least includes the following process: taking the edible part of the fruit for juice extraction to obtain the fruit juice.

[0012] The kefir fermentation product as described above, wherein the raw materials of the kefir fermentation base material include, by mass percentage: 30 - 90% of raw milk, 0 - 1% of stabilizer, 4 - 13% of sweetening substance, 0.001 - 0.1% of kefir starter, and the balance is water.

[0013] The kefir fermentation product as described above, wherein the kefir fermentation base material is kefir fermented milk or kefir lactic acid bacteria beverage.

[0014] The kefir fermentation product as described above, wherein the kefir fermented milk is prepared by a method that at least includes the following process:

[0015] 1) Adding the stabilizer, sweetening substance, and water to the first raw material system including the raw milk, and mixing to obtain the first material;

[0016] 2) Subjecting the first material to homogenization, sterilization, and cooling treatments in sequence to obtain the second material;

[0017] 3) Adding the kefir starter to the second material for fermentation, and terminating the fermentation when the acidity of the fermentation system reaches 70 - 80 °T or pH < 4.5 to obtain the kefir fermented milk;

[0018] The kefir lactic acid bacteria beverage is prepared by a method that at least includes the following process:

[0019] 1) Subjecting the kefir fermented milk to homogenization treatment to obtain the third material;

[0020] 2) Diluting the second raw material system including the stabilizer and sweetening substance with the water to obtain the fourth material;

[0021] 3) Mixing and homogenizing the third material and the fourth material to obtain the kefir lactic acid bacteria beverage.

[0022] The present invention also provides a preparation method of the kefir fermentation product according to any one of the above, including the following steps:

[0023] 1) Mixing the kefir fermentation base material and the fruit juice to obtain a mixed material;

[0024] 2) Place the mixed material at 20 - 30°C for 4 - 10 h to obtain the kefir fermentation product.

[0025] The preparation method as described above, wherein, before step 2), filling the mixed material is further included.

[0026] The present invention provides a kefir fermentation product. The raw materials of the kefir fermentation product include a kefir fermentation base material and fruit juice, and it is defined that the mass ratio of the kefir fermentation base material to the fruit juice is (90 - 99) : (1 - 10), wherein the total acid of the fruit juice ≥ 1.0%; the above-mentioned kefir fermentation product is prepared by at least a method including the following process: after mixing the above-mentioned kefir fermentation base material and fruit juice, place it at 20 - 30°C for 4 - 10 h to obtain the above-mentioned kefir fermentation product. By defining that the total acid of the fruit juice ≥ 1.0% and placing the above-mentioned mixed system at 20 - 30°C for 4 - 10 h, the tingling sensation of the kefir fermentation product is synergistically enhanced, making the kefir fermentation product of the present invention have a strong tingling sensation like that of a carbonated beverage. Detailed implementation manners

[0027] To make the purpose, technical solutions and advantages of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative efforts belong to the scope of protection of the present invention.

[0028] The first aspect of the present invention provides a kefir fermentation product. The raw materials of the kefir fermentation product include a kefir fermentation base material and fruit juice, and the mass ratio of the kefir fermentation base material to the fruit juice is (90 - 99) : (1 - 10), wherein the total acid of the fruit juice ≥ 1.0%;

[0029] The above-mentioned kefir fermentation product is prepared by at least a method including the following process: after mixing the above-mentioned kefir fermentation base material and fruit juice, place it at 20 - 30°C for 4 - 10 h to obtain the above-mentioned kefir fermentation product.

[0030] The above-mentioned kefir fermentation base material refers to an alcoholic fermentation product containing acid, alcohol and a small amount of carbon dioxide gas, which is prepared by fermenting raw materials such as cow's milk or goat's milk with a kefir fermentation agent, such as kefir grains.

[0031] The total acid of the above-mentioned fruit juice ≥ 1.0% means that the acid in the fruit juice is titrated with sodium hydroxide, using phenolphthalein as an indicator, and the amount of sodium hydroxide used is converted into the molar amount of citric acid. The ratio of the molar amount of this citric acid to the volume of the fruit juice is the above-mentioned total acid content.

[0032] Since the above-mentioned kefir fermented product is a low-temperature stored food, during low-temperature storage, the activity of the kefir starter in the kefir fermentation base material is relatively low and cannot continuously ferment. However, when the above-mentioned kefir fermentation base material and fruit juice with a total acid ≥ 1.0% are mixed at a mass ratio of (90 - 99) : (1 - 10) and placed at 20 - 30 °C for 4 - 10 h, during this process, the acidic fruit juice and room-temperature placement act synergistically, significantly enhancing the activity of the kefir starter, enabling it to continuously ferment to produce fermentation metabolites, including acids, alcohols, and carbon dioxide gas, thereby significantly enhancing the kefir flavor of the product and the fizzy feeling similar to that of carbonated drinks, and finally obtaining a kefir fermented product with a strong fizzy feeling.

[0033] The mass ratio of the above-mentioned kefir fermentation base material to the above-mentioned fruit juice is (90 - 99) : (1 - 10), which can be understood as the ratio of the mass of the fruit juice to the mass of the kefir fermented product obtained after mixing the kefir fermentation base material and the fruit juice is 1% - 10%, that is, the mass percentage content of the fruit juice in the kefir fermented product is 1% - 10%.

[0034] To avoid the loss of gases such as carbon dioxide, which would lead to a weakened fizzy feeling of the product, the above mixing and placement processes should be carried out in a closed space or a sealed device. That is to say, after mixing the above-mentioned kefir fermentation base material and the above-mentioned fruit juice and placing it at 20 - 30 °C for 4 - 10 h, the entire process of obtaining the above-mentioned kefir fermented product should be carried out in a closed space or a sealed device.

[0035] On the premise of ensuring that the gas in the product will not be lost, the mixing of the above-mentioned kefir fermentation base material and the fruit juice can occur before filling, or can be carried out in the filling pipeline, or can also be carried out when filling into the packaging container, as long as it is ensured that the above operations are carried out in a closed environment and will not cause gas loss, which would lead to a reduction in the fizzy feeling of the product.

[0036] The above-mentioned kefir fermented product combines the nutrition of fruit juice and kefir fermented dairy products, is rich in nutrition, has a high health value, and at the same time combines the milk flavor, kefir flavor, and fruit flavor of fermented dairy products. More importantly, the above-mentioned kefir fermented product has a strong fizzy feeling similar to that of carbonated drinks.

[0037] Furthermore, when the mass ratio of the above-mentioned kefir fermentation base material to the above-mentioned fruit juice is (92 - 98) : (2 - 8), the obtained kefir fermented product has a stronger fizzy feeling, and the fermented milk flavor, kefir flavor, and fruit flavor are properly matched, further improving the flavor and taste of the product.

[0038] The mass ratio of the above-mentioned kefir fermentation base material to the above-mentioned fruit juice is (92 - 98):(2 - 8), which can be understood as the ratio of the mass of the fruit juice to the mass of the kefir fermentation product obtained by mixing the kefir fermentation base material and the fruit juice is 2% - 8%, that is, the mass percentage content of the fruit juice in the kefir fermentation product is 2% - 8%.

[0039] Furthermore, when the above-mentioned kefir fermentation base material and the above-mentioned fruit juice are mixed and placed at 25 - 30 °C for 6 h, at this time, the activity of the kefir ferment is higher, which helps to further improve the fizz of the product and maintain the fizz of the product at a more appropriate level.

[0040] Generally, the above-mentioned fruit juice includes at least one of berry fruit juice, stone fruit juice, melon fruit juice, pome fruit juice, and hesperidium fruit juice. The above-mentioned fruit juice is rich in citric acid, and some also contain malic acid. Citric acid and malic acid, especially citric acid, can activate and accelerate the citric acid metabolic pathway of the kefir ferment, making it continuously produce metabolites, promoting gas production, and thus significantly increasing the fizz of the product.

[0041] When the above-mentioned fruit juice uses hesperidium fruit juice, such as lemon juice and orange juice, because it contains more citric acid and its acidity is more suitable, the fizz of the product is increased more significantly.

[0042] The above-mentioned fruit juice is prepared by at least a method including the following process: taking the edible part of the fruit and performing juice extraction treatment to obtain the above-mentioned fruit juice.

[0043] Generally, the total acid of the above-mentioned fruit juice obtained by juicing fresh fruit is ≥1.0%. In particular, when the total acid of the juice of some fruits is <1.0%, citric acid can be added alone to make its total acid ≥1.0%, thereby ensuring that it can significantly increase the fizz of the kefir fermentation product.

[0044] It can be understood that when the total acid of the fruit juice is too much, an alkali or a buffer substance can be added to neutralize the acidity and reduce the total acid content.

[0045] In some embodiments, the raw materials of the above-mentioned kefir fermentation base material include, by mass percentage: 30 - 90% of raw milk, 0 - 1% of stabilizer, 4 - 13% of sweetening substance, 0.001 - 0.1% of kefir ferment, and the balance is water.

[0046] The raw milk used in the present invention refers to fresh milk or reconstituted milk that meets the national fresh raw milk purchase standard, and can also be at least one of whole milk, partially skimmed milk, fully skimmed milk, and low-fat milk.

[0047] The above stabilizers include at least one of pectin, carboxymethyl cellulose, gellan gum, propylene glycol alginate, and soluble soybean polysaccharide. Among them, in the raw materials of the above kefir fermentation base material, the mass percentage content of soluble soybean polysaccharide is 0.8% or less, and the mass percentage content of pectin is 0.3% or less; it should be noted that whether the above stabilizers contain both soluble soybean polysaccharide and pectin, or only contain one of them, the mass percentage contents of soluble soybean polysaccharide and pectin need to be controlled within the above ranges, which is beneficial to further improving the stability of the product.

[0048] The above stabilizers also include at least one of thickeners and emulsifiers.

[0049] The above thickeners include at least one of locust bean gum, gelatin, agar, gum arabic, guar gum, xanthan gum, carrageenan, oxidized hydroxypropyl starch, etc., which can better achieve the stability of the product.

[0050] The above emulsifiers include at least one of glycerol monostearate, glycerol distearate, polyglycerol esters, sucrose esters, sodium stearoyl lactate, monoglyceryl citrate, monoglyceryl tartrate, monoglyceryl succinate, monoglyceryl acetate, sodium caseinate, etc.

[0051] The above sweet substances include at least one of granulated sugar, glucose, fructose, galactose, and fructose syrup.

[0052] The kefir starter used in the present invention is a mixed strain containing Lactococcus lactis subsp. lactis, Lactococcus cremoris, Leuconostoc mesenteroides subsp. mesenteroides, or a mixed strain containing Leuconostoc mesenteroides subsp. mesenteroides and Lactococcus lactis subsp. lactis (diacetyl type). It can rapidly increase its activity under the action of acidic juice during the process of being placed at 20 - 30 °C for 4 - 10 h, stimulate the citric acid metabolic pathway, produce more metabolites, and thus more significantly improve the fizzy taste of the kefir fermentation product of the present invention, and help improve the stability of the fizzy taste of this product.

[0053] The above kefir starter also includes at least one of Bifidobacterium animalis subsp. lactis, Bifidobacterium longum subsp. longum, Bifidobacterium longum subsp. infantis, Lactobacillus delbrueckii subsp. bulgaricus, Streptococcus salivarius subsp. thermophilus, Lactococcus lactis subsp. lactis, Lactococcus cremoris, Lactobacillus casei, Lactobacillus paracasei, Lactobacillus rhamnosus, Lactobacillus mucosae, Lactobacillus reuteri, Lactiplantibacillus plantarum, Limosilactobacillus fermentum, Limosilactobacillus reuteri, Lactobacillus buchneri, Lactobacillus hilgardii, Propionibacterium acidipropionici, Weissella cibaria, and Carnobacterium maltaromaticum, which helps to further enhance the fizzy taste of the kefir fermentation product of the present invention, and further enhance the probiotic characteristics and health value of the above product by increasing the types of probiotics.

[0054] The kefir base material can be prepared from the above raw material formula. After mixing the kefir base material with fruit juice having a total acid content of ≥1.0% and leaving it at 20 - 30 °C for 4 - 10 h, the gas production capacity of the kefir starter can be significantly improved, and finally a kefir fermented product with a self-carbonating effect and a strong astringent taste can be obtained.

[0055] In addition, the raw materials of the above kefir fermentation base material also include at least one of dietary fiber, compound nutrients, fruit and vegetable juice, table salt, edible essence, acidity regulator, and conventional excipients, so as to endow the product with more abundant nutrition or further improve the product flavor and increase the variety of products.

[0056] The present invention does not make special limitations on the types and amounts of the above substances added, and those skilled in the art can select and determine according to actual needs.

[0057] Among them, the above acidity regulator includes at least one of lactic acid, citric acid, malic acid, tartaric acid, and phosphoric acid, and its mass percentage content in the raw materials of the kefir fermentation base material is 0.001% - 0.1%. The above conventional excipients include at least one of light cream, cream, anhydrous cream, evaporated milk, sweetened condensed milk, concentrated whey protein, and concentrated milk protein, which can be used to adjust the taste of the formulated milk or the solid content index of the material. The additives of the above conventional excipients need to be determined according to the requirements of the nutritional component content of the product; when the above conventional excipient is a sweetened excipient, the content of the sweet substance in the raw materials of the kefir fermentation base material should be correspondingly reduced to facilitate controlling the sweetness of the whole product within a reasonable range.

[0058] According to the content of milk protein in the kefir fermentation base material, the above kefir fermentation base material can be divided into kefir fermented milk or kefir lactic acid bacteria beverage.

[0059] Specifically, when the content of raw milk in the raw materials of the kefir fermentation base material is 80 - 90 wt%, the milk protein content in the kefir fermentation base material is ≥2.3 wt%, the fat content is ≥2.5 wt%, and the total number of lactic acid bacteria is ≥1×10 6 CFU / mL, the kefir fermentation base material is usually called kefir fermented milk; when the content of raw milk in the raw materials of the kefir fermentation base material is 30 - 80 wt%, the milk protein content in the kefir fermentation base material is ≤2.3 wt%, and the total number of lactic acid bacteria is ≥1×10 6 CFU / mL, the kefir fermentation base material is usually called kefir lactic acid bacteria beverage.

[0060] The kefir lactic acid bacteria beverage can be further subdivided into live bacteria-containing milk beverages and active lactic acid bacteria beverages according to the milk protein content in the product. When 1.0 wt% ≤ milk protein content ≤ 2.3 wt%, it is usually called a live bacteria-containing milk beverage, and when 0.7 wt% ≤ milk protein content ≤ 1.0 wt%, it is usually called an active lactic acid bacteria beverage.

[0061] The above-mentioned kefir fermented milk is prepared by a method including at least the following processes:

[0062] 1) Add a stabilizer, a sweetening substance, and water to a first raw material system including raw milk, and obtain a first material after mixing.

[0063] 2) Homogenize, sterilize, and cool the first material in sequence to obtain a second material.

[0064] 3) Add a kefir starter to the second material for fermentation, and terminate the fermentation when the acidity of the fermentation system reaches 70-80°T or pH < 4.5 to obtain kefir fermented milk.

[0065] The above-mentioned kefir lactic acid bacteria beverage is prepared by a method including at least the following processes:

[0066] 1) Homogenize the above-mentioned kefir fermented milk to obtain a third material.

[0067] 2) Dilute a second raw material system including a stabilizer and a sweetening substance with water to obtain a fourth material.

[0068] 3) Mix and homogenize the third material and the fourth material to obtain the above-mentioned kefir lactic acid bacteria beverage.

[0069] During the preparation process of the above-mentioned kefir fermented milk:

[0070] In step 1), the present invention does not limit the addition order of the above-mentioned stabilizer, sweetening substance, and water. For example, the first raw material system including raw milk can be heated to 65°C first, and after starting stirring, the stabilizer, sweetening substance, and water can be directly added to promote the full mixing of the above components to obtain the first material; or the water can be heated to 65°C first, mixed with the first raw material system including raw milk, and then the stabilizer and sweetening substance are added, and after stirring and mixing evenly, the first material is obtained.

[0071] The present invention does not make a special limitation on the stirring time above. Generally, stirring for 30-40 min is beneficial to uniform mixing.

[0072] In step 2), the processes of homogenizing, sterilizing, and cooling the first material in sequence are all conventional technical means in the art. The present invention does not limit the specific operating conditions of the above technical means. Generally, the homogenization pressure can be 15-30 Mpa, the homogenization temperature is 60-70°C; the sterilization conditions are 93-97°C, 5-10 min; the cooling temperature is 28-37°C.

[0073] In step 3), the temperature of the second material is maintained at 28-37°C. At this time, the kefir starter is added to the second material. The kefir starter can quickly recover its activity within the above temperature range, which is convenient for efficient and high-quality fermentation. That is to say, the temperature of the second material should be set to an inoculation temperature suitable for the growth and reproduction of the kefir starter of the present invention.

[0074] When the acidity of the fermentation system reaches 70-80°T or pH <4.5, the fermentation is terminated to obtain kefir fermented milk.

[0075] The above acidity reaches 70-80°T or pH<4.5, choose one as the indicator to judge the end point of fermentation.

[0076] The temperature of the fermentation process, i.e., the fermentation temperature, can be set according to the type of kefir starter. The fermentation time can be determined by controlling the amount of kefir starter added, the fermentation temperature, the fermentation end point, etc.

[0077] Generally, the above fermentation temperature and fermentation time are suitable for most freeze-dried direct-injection starter cultures.

[0078] During the preparation of the above kefir lactic acid bacteria beverage:

[0079] In step 1, if the kefir fermented milk is freshly fermented, the kefir fermented milk can be cooled to room temperature and then homogenized; homogenization is conducive to obtaining a third material with uniform texture and delicate taste, which is conducive to preparing a kefir lactic acid bacteria beverage with a stable system and uniform texture.

[0080] The present invention does not specifically limit the homogenization conditions. Generally, the homogenization pressure is 15-30Mpa.

[0081] In step 2), the sweetener includes at least one of sugar alcohol raw materials, sweetening additives, and white sugar. Generally, the second raw material system is prepared by first adding sugar alcohol raw materials, and then adding at least one of white sugar, stabilizers, and sweetening additives.

[0082] After dilution with water, the diluted material can be stirred for 30-40 minutes, which is conducive to promoting the full mixing of various raw materials.

[0083] In step 3), the role of homogenization is to promote more uniform mixing of the third material and the fourth material, and the homogenization pressure can be 15-30MPa.

[0084] Generally, the third material accounts for 20%-75% of the total weight of the kefir lactic acid bacteria beverage raw materials.

[0085] The above-mentioned kefir fermentation base material includes kefir fermented milk or kefir lactic acid bacteria beverage. Its preparation process has a mature process and convenient operation. Through the above preparation process, kefir fermented milk or kefir lactic acid bacteria beverage with good taste and high stability can be prepared.

[0086] To avoid contamination by miscellaneous bacteria, the fourth material is also sterilized in step 2) of the above-mentioned preparation process of kefir lactic acid bacteria beverage. The sterilization conditions can be sterilization at 95 °C for 300 s. In addition, the sterilized fourth material should be cooled to below 30 °C before being mixed with the third material to avoid killing the live bacteria in the third material at high temperature.

[0087] To enrich the taste of kefir fermented milk or kefir lactic acid bacteria beverage, in step 1) of the above-mentioned preparation process of kefir fermented milk, the raw milk can be subjected to browning treatment first to obtain brown raw milk, and the above-mentioned brown raw milk is used instead of raw milk to prepare brown kefir fermented milk or brown kefir lactic acid bacteria beverage.

[0088] The essence of the above-mentioned browning treatment process is the Maillard reaction, which at least includes the following process: adding a reducing sugar raw material to the raw milk, treating it at 115 °C for 5 - 10 min or in a water bath at 90 °C or above for 3 - 4 h to obtain browned raw milk.

[0089] The above-mentioned reducing sugar raw material includes at least one of glucose, fructose, galactose, and fructose syrup. Calculated as monosaccharides, the mass percentage content of the above-mentioned reducing sugar raw material in the raw materials of the final kefir fermentation product is 0.2 - 8%.

[0090] In addition, in the above-mentioned browning treatment process, lactase can be used to hydrolyze the lactose in the raw milk first, and then the hydrolyzed raw milk is treated at 115 °C for 5 - 10 min or in a water bath at 90 °C or above for 3 - 4 h to obtain browned raw milk. Since lactase hydrolyzes lactose into glucose and galactose, providing a reducing sugar raw material for the browning treatment, there is no need to add additional reducing sugar raw materials.

[0091] It can be understood that the above-mentioned browning treatment can be carried out after mixing water and raw milk first.

[0092] In addition, the obtained brown raw milk should be cooled to 65 °C, and then it is used instead of raw milk to be mixed with other raw materials to obtain the first material, which is beneficial to promoting the uniform mixing of various raw materials.

[0093] The second aspect of the present invention provides a preparation method of the kefir fermentation product of the first aspect, including the following steps:

[0094] 1) Mix the kefir fermentation base material and fruit juice to obtain a mixed material;

[0095] 2) Place the mixed material at 20 - 30°C for 4 - 10 h to obtain the above-mentioned kefir fermentation product.

[0096] To avoid the loss of gases such as carbon dioxide, which may lead to a weakened fizzy feeling in the product, the above mixing and placing processes should be carried out in a closed space or a sealed device. That is to say, the entire process of mixing the kefir fermentation base material and the fruit juice to obtain the mixed material, and then placing the mixed material at 20 - 30°C for 4 - 10 h to obtain the above-mentioned kefir fermentation product should be carried out in a closed space or a sealed device.

[0097] The present invention does not particularly limit the timing of mixing the kefir fermentation base material and the fruit juice in step 1) above, as long as it is ensured that the carbon dioxide gas in the product will not be lost. For example, the kefir fermentation base material and the fruit juice can be mixed in a closed space or a sealed device before filling to obtain the mixed material; they can also be mixed in the filling pipeline to obtain the mixed material; or they can be mixed when the kefir fermentation base material and the fruit juice are simultaneously filled into the finished product packaging at the end of the filling process to obtain the mixed material. The above mixing process only needs to ensure that it is carried out in a closed space or environment without causing gas loss, which may lead to a reduced fizzy feeling in the product.

[0098] The filling process in the existing production process line of fermentation products includes an automatic jam addition and on-line premixing system, which can directly mix some raw materials with the fermentation product in a closed filling pipeline. Therefore, without changing the existing production process line of fermentation products, in the filling process, by adding the above-mentioned fruit juice through the automatic jam addition and on-line premixing system, the kefir fermentation base material and the fruit juice can be mixed in a closed filling pipeline to obtain the mixed material.

[0099] Since the kefir starter in the above-mentioned kefir fermentation base material has a low activity during low-temperature storage and cannot continuously ferment to produce gas. However, after mixing the above-mentioned kefir fermentation base material and the fruit juice with a total acid ≥ 1.0% and placing it at 20 - 30°C for 4 - 10 h, the acidic fruit juice and the room-temperature placement synergistically improve the activity of the kefir starter, enabling it to continuously ferment to produce fermentation metabolites, including acids, alcohols, and carbon dioxide gas, which can significantly enhance the kefir flavor of the product and the fizzy feeling like that of a carbonated drink, and finally obtain a kefir fermentation product with a strong fizzy feeling.

[0100] The above preparation method has a simple process and convenient operation, and is suitable for industrial production; through the above preparation method, a kefir fermentation product with a strong astringent taste can be obtained. During the shelf life of this kefir fermentation product, there is no precipitation or stratification, the texture is uniform, the color is stable, the acidity is constant or has a small increase, and there is no obvious peculiar smell. It has good flavor, taste and tissue state; this kefir fermentation product organically combines fruit juice and kefir fermented dairy products, is rich in nutrition, suitable for long-term consumption by the general population of all ages, and is beneficial to human health.

[0101] When the above kefir fermentation product is stirred kefir yogurt, in step 2) above, after obtaining the kefir fermentation product, it needs to be refrigerated and ripened at 2 - 6 °C for 12 - 24 hours to obtain stirred kefir yogurt.

[0102] When the above kefir fermentation product is drinking kefir yogurt, before step 1) above, the kefir fermentation base material needs to be homogenized to obtain a homogenized kefir fermentation base material, and in step 1), the above homogenized kefir fermentation base material and fruit juice are mixed.

[0103] The above homogenization pressure can be 0 - 10 MPa.

[0104] Generally, since the above kefir fermentation product is a low-temperature storage fermentation product, and in order to further improve its astringent taste and make its taste more refreshing, after the mixed material is placed at 20 - 30 °C for 4 - 10 h in step 2) above, the mixed material needs to be transferred to cold storage for storage, and the above cold storage temperature is generally 4 - 10 °C.

[0105] The equipment used in the preparation method of the present invention can all adopt the well-known equipment in the field, such as a homogenizer for homogenization, a batching tank for mixing raw materials, a fermentation tank for fermentation, and a sterilization device, etc. In addition, the filling of the above kefir lactic acid bacteria beverage can be carried out according to the existing filling technology of liquid products in the field.

[0106] Before step 2) above, filling the mixed material is also included.

[0107] Adding the fruit juice through the above automatic jam adding and online premixing system, the mixed material of the kefir fermentation base material and the fruit juice can be obtained in a closed filling pipeline. Filling the mixed material before step 2), and placing the filled mixed material at 20 °C - 30 °C for 4 - 10 h, a kefir fermentation product with a strong astringent taste like a carbonated beverage can be obtained.

[0108] It is understandable that the above-mentioned mixed material after filling can be directly placed at 20°C - 30°C for 4 - 10 h, then refrigerated at 4°C and consumed after refrigeration; it can also be first refrigerated at 4°C for a period of time, then transferred to 20°C - 30°C for 4 - 10 h, and then refrigerated before consumption. All of the above operations can obtain a kefir fermentation product with a strong carbonated beverage-like tingling sensation.

[0109] Hereinafter, the kefir fermentation product of the present invention and its preparation method will be introduced in more detail through specific examples.

[0110] The specific sources of some raw materials in the following preparation process are as follows:

[0111] Various fruit juices / fruit pulps are purchased from Greer Juice Industry (Tianjin) Co., Ltd., or single-strength juices obtained by diluting the purchased raw materials, or fruit juices / fruit pulps with a specific total acid content prepared according to the above-mentioned fruit juice preparation method;

[0112] The kefir starter is purchased from Chr. Hansen (Beijing) Trading Co., Ltd., including: CHN22:BMY-03 = 1:2, where CHN22 includes Lactococcus lactis subsp. lactis, Lactococcus lactis subsp. cremoris, Lactococcus lactis subsp. diacetylactis, and BMY-03 includes Streptococcus thermophilus, Lactobacillus bulgaricus, Bifidobacterium animalis, Lactobacillus acidophilus, Bifidobacterium lactis, Lactococcus lactis subsp. lactis, Lactococcus lactis subsp. cremoris;

[0113] Milk: Purchased by Yili Co., Ltd. itself;

[0114] White granulated sugar: Purchased by Yili Co., Ltd. itself.

[0115] Example 1

[0116] A kefir fermentation product of this example includes the following raw materials by mass (the total amount of raw materials is calculated as 1000 kg):

[0117] 840 kg of milk, 60 kg of white granulated sugar, 100 g of kefir starter, 50 kg of apple juice, and the balance is water; among them, the total acid of the apple juice is ≥1.0%.

[0118] The preparation method of the above-mentioned kefir fermentation product includes the following steps:

[0119] 1) After heating the milk to 55°C, add white granulated sugar and water, and at the same time turn on the stirring for 30 - 40 min for material melting to obtain the first material;

[0120] 2) After preheating the above-mentioned first material to 65°C, perform homogenization, sterilization, and cooling treatments in sequence, where the homogenization pressure is 15 MPa, the sterilization temperature is 95°C, the sterilization time is 300 s, and the cooling temperature is 37°C to obtain the second material;

[0121] 3) Add kefir starter to the above-mentioned second material for fermentation, and terminate the fermentation when the acidity of the fermentation system reaches 70°T. At this time, the fermentation time is 5 h to obtain a kefir fermentation base material;

[0122] 4) After cooling the above-mentioned kefir fermentation base material to room temperature, mix it evenly with the above-mentioned apple juice to obtain a mixed material;

[0123] 5) Place the above-mentioned mixed material at 25 °C for 4 h, and then transfer it to a refrigerator at 4 - 10 °C to obtain the above-mentioned kefir fermentation product.

[0124] Example 2

[0125] This example is basically the same as Example 1, except that:

[0126] Replace 20 kg of apple juice with a total acid of 1.0% with lemon juice with a total acid ≥ 1.5%.

[0127] Example 3

[0128] This example is basically the same as Example 1, except that

[0129] The addition amount of apple juice is 10 kg.

[0130] Example 4

[0131] This example is basically the same as Example 1, except that

[0132] The addition amount of apple juice is 20 kg.

[0133] Example 5

[0134] This example is basically the same as Example 1, except that

[0135] The addition amount of apple juice is 30 kg.

[0136] Example 6

[0137] This example is basically the same as Example 1, except that

[0138] The addition amount of apple juice is 40 kg.

[0139] Example 7

[0140] This example is basically the same as Example 1, except that

[0141] The addition amount of apple juice is 60 kg.

[0142] Example 8

[0143] This example is basically the same as Example 1, except that

[0144] The addition amount of apple juice is 70 kg.

[0145] Example 9

[0146] This example is basically the same as Example 1, with the difference that

[0147] The addition amount of apple juice is 80 kg.

[0148] Example 10

[0149] This example is basically the same as Example 1, with the difference that

[0150] The addition amount of apple juice is 90 kg.

[0151] Example 11

[0152] This example is basically the same as Example 1, with the difference that

[0153] The addition amount of apple juice is 100 kg.

[0154] Example 12

[0155] This example is basically the same as Example 1, with the difference that

[0156] In step 5) of the preparation method, it is modified that the above-mentioned mixed material is refrigerated at 4°C for 7 days, then transferred to 25°C and placed for 6 h, and then transferred to 4°C for refrigeration to obtain the above-mentioned kefir fermentation product.

[0157] Example 13

[0158] A kefir fermentation product of this example comprises raw materials with the following masses (the total amount of raw materials is calculated as 1000 kg):

[0159] 400 kg of milk, 90 kg of granulated sugar, 100 g of kefir starter, 50 kg of lemon juice, 0.2 kg of high-ester pectin, 100 g of strain, and the balance is water; wherein, the total acid of the lemon juice is ≥1.5%, and the strain is CHOOZIT Kefir mid 01LYO 2000.

[0160] The preparation method of the above-mentioned kefir fermentation product comprises the following steps:

[0161] 1) After heating the milk to 55°C, add granulated sugar and water, and at the same time turn on the stirring for 30 - 40 min for material melting to obtain the first material;

[0162] 2) After preheating the above-mentioned first material to 65°C, successively carry out homogenization, sterilization, and cooling treatments, wherein the homogenization pressure is 15 MPa, the sterilization temperature is 95°C, the sterilization time is 300 s, and the cooling temperature is 30°C to obtain the second material;

[0163] 3) Add kefir starter to the above-mentioned second material for fermentation, and terminate the fermentation when the acidity of the fermentation system reaches 70°T. At this time, the fermentation time is 8 h to obtain the first base material;

[0164] 4) After cooling the above-mentioned first base material to room temperature, carry out homogenization treatment under sterile conditions. Among them, the homogenization pressure is 15 MPa to obtain the third material;

[0165] 5) Dilute granulated sugar and high-ester pectin with water and carry out sterilization treatment. Among them, the sterilization temperature is 95 °C and the sterilization time is 300 s. After cooling to 30 °C, obtain the fourth material;

[0166] 6) Mix the above-mentioned third material and fourth material and homogenize at 18 MPa. Among them, the mass percentage of the third material in the raw materials of the product in this example is 45% to obtain the kefir fermentation base material;

[0167] 7) Mix the above-mentioned kefir fermentation base material and the above-mentioned lemon juice evenly to obtain a mixed material;

[0168] 8) Place the above-mentioned mixed material at 25 °C for 5 h, then transfer it to refrigerate at 4-10 °C to obtain the above-mentioned kefir fermentation product.

[0169] Example 14

[0170] This example is basically the same as Example 1, the difference is:

[0171] 1) Replace 50 kg of apple juice with 10 kg of apple juice, and make up the balance with water;

[0172] 2) In step 5), replace placing at 25 °C for 4 h with placing at 20 °C for 10 h.

[0173] Example 15

[0174] This example is basically the same as Example 1, the difference is:

[0175] 1) Replace 50 kg of apple juice with 100 kg of apple juice, and make up the balance with water;

[0176] 2) In step 5), replace placing at 25 °C for 4 h with placing at 30 °C for 7 h.

[0177] Example 16

[0178] This example is basically the same as Example 1, the difference is:

[0179] 1) Replace 50 kg of apple juice with 20 kg of apple juice, and make up the balance with water;

[0180] 2) In step 5), replace the placement for 4 h with a placement for 6 h.

[0181] Example 17

[0182] This example is basically the same as Example 1, except that:

[0183] 1) Replace the apple juice with a mass of 50 kg with apple juice with a mass of 80 kg, and make up the balance with water;

[0184] 2) In step 5), replace the placement for 4 h with a placement for 6 h.

[0185] Comparative Example 1

[0186] This comparative example is basically the same as Example 1, except that: no apple juice is added.

[0187] Comparative Example 2

[0188] This comparative example is basically the same as Example 1, except that:

[0189] In the preparation method, step 5) is modified to directly refrigerate the above-mentioned mixed material at 4 - 10 °C to obtain the above-mentioned kefir fermentation product.

[0190] Comparative Example 3

[0191] This comparative example is basically the same as Example 1, except that:

[0192] Replace the apple juice with freshly squeezed watermelon juice with 0.5% ≤ total acid < 1.0%.

[0193] Comparative Example 4

[0194] This comparative example is basically the same as Example 1, except that:

[0195] Replace the apple juice with decolorized and deacidified apple juice with a total acid of ≤ 0.05%.

[0196] Comparative Example 5

[0197] This comparative example is basically the same as Example 1, except that:

[0198] In the preparation method, add the apple juice in step 1); at the same time, modify step 4) to obtain the mixed material after cooling the above-mentioned kefir fermentation base to room temperature.

[0199] Comparative Example 6

[0200] This comparative example is basically the same as Example 1, except that:

[0201] Replace the apple juice with strawberry pulp with 0.5% ≤ total acid < 1.0%.

[0202] Comparative Example 7

[0203] This comparative example is basically the same as Example 1, with the difference that:

[0204] The apple juice is replaced with peach pulp with 0.5% ≤ total acid < 1.0%.

[0205] Comparative Example 8

[0206] This comparative example is a sample with a carbon dioxide volume fraction (percentage of carbon dioxide volume to sample mass) of 1.5%, and is prepared through the following steps:

[0207] 1) Prepare an aqueous solution of granulated sugar with a mass percentage of granulated sugar of 6%;

[0208] 2) Charge carbon dioxide into the above-mentioned aqueous solution of granulated sugar using a carbon dioxide quantitative gas-filling device to obtain a sample with a carbon dioxide volume fraction (percentage of carbon dioxide volume to sample mass) of 1.5%.

[0209] Comparative Example 9

[0210] This comparative example is the kefir fermentation base material prepared in Example 1.

[0211] Comparative Example 10

[0212] This comparative example is basically the same as Example 13, with the difference that:

[0213] The lemon juice is replaced with an equal amount of water.

[0214] Comparative Example 11

[0215] This comparative example is basically the same as Example 1, with the difference that:

[0216] 5 kg of apple juice is replaced with 50 kg of apple juice, and the balance is made up with water.

[0217] Comparative Example 12

[0218] This comparative example is basically the same as Example 1, with the difference that:

[0219] 120 kg of apple juice is replaced with 50 kg of apple juice, and the balance is made up with water.

[0220] Comparative Example 13

[0221] This comparative example is basically the same as Example 1, with the difference that:

[0222] The apple juice with a total acid of 1.0% is replaced with apple juice with a total acid of 0.7%.

[0223] Comparative Example 14

[0224] This comparative example is basically the same as Example 1, with the difference that:

[0225] Replace the apple juice with an acidity of 1.0% with apple juice with an acidity of 0.8%.

[0226] Comparative Example 15

[0227] This comparative example is basically the same as Example 1, except that:

[0228] In step 5), replace 25°C with 42°C.

[0229] Comparative Example 16

[0230] This comparative example is basically the same as Example 1, except that:

[0231] In step 5), replace 25°C with 15°C.

[0232] Comparative Example 17

[0233] This comparative example is basically the same as Example 1, except that:

[0234] In step 5), replace 4 h with 3 h.

[0235] Comparative Example 18

[0236] This comparative example is basically the same as Example 1, except that:

[0237] In step 5), replace 4 h with 24 h.

[0238] Test Example

[0239] 1. Detect the following parameters for the above examples and comparative examples:

[0240] 1) Sensory evaluation of the tingling sensation of the product: Score the tingling sensation of the product according to the following scoring criteria. If the tingling sensation cannot be perceived, it is scored 0 - 1 point; if the tingling sensation can be perceived, it is scored 2 - 10 points; if the tingling sensation is significantly stimulating, it is scored 10 - 20 points; if the tingling sensation is strong, it is scored 20 - 30 points. The specific results are shown in Table 1;

[0241] 2) Total number of lactic acid bacteria in the product: Determine the total number of lactic acid bacteria in the product within the shelf life at 20°C by the method specified in the National Food Safety Standard Food Microbiology Examination - Examination of Lactic Acid Bacteria (GB 4789.35 - 2010). The specific results are shown in Table 2.

[0242] 2. Test results

[0243] Table 1 Tingling sensation of the product

[0244]

[0245]

[0246] The results in Table 1 show that:

[0247] 1) After fermentation is completed, storing at room temperature or warming up after refrigeration and then refrigerating again will significantly enhance the fizzy feeling. If refrigeration is carried out directly after fermentation is completed, the enhancement degree of the fizzy feeling is not significant.

[0248] 2) Within the addition range of the fruit juice raw materials of the present invention, adding fruit juice has a promoting effect on the fizzy feeling of kefir fermented dairy products. When the addition amount of apple juice reaches 2%, the fizzy feeling of kefir fermented milk begins to become stronger, and with the increase of the addition amount, the intensity of the fizzy feeling also increases. However, in the experiment, it was also found that when the addition amount of apple juice exceeds 8%, the promoting effect on the fizzy feeling of the corresponding product does not increase significantly. Therefore, the preferred addition amount of apple juice is 2%-8%.

[0249] 3) According to the experimental results, the decolorized and deacidified fruit juice has no obvious promoting effect on the gas production of kefir fermented milk. Therefore, the fruit juice raw material is preferably non-decolorized and deacidified apple juice.

[0250] 4) According to the experimental results, adding the fruit juice in advance during the batching process will not significantly promote the increase in the gas production of kefir fermented milk.

[0251] Table 2 Total number of lactic acid bacteria in the product (CFU / mL)

[0252]

[0253]

[0254]

[0255] The results in Table 2 show that:

[0256] When the addition amount of apple juice is from 10 - 60 g / kg, the number of viable bacteria will increase with the increase of the addition amount of apple juice. However, when it exceeds 60 g / kg, the increase of apple juice will not have a significant impact on the number of viable bacteria in the lactic acid bacteria beverage. However, a 5% addition amount of lemon juice will affect the number of viable bacteria during the product shelf life. In addition, when using fruit juice with a total acid less than 1%, the number of viable bacteria in its product is less than that when using fruit juice with a total acid greater than 1%. In short, the length of time for the product to be stored at room temperature, too high or too low temperature will all have a certain impact on the number of viable bacteria and gas production of the product.

[0257] Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements on some or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A kefir fermented product, characterized in that: The raw materials of the kefir fermented product include kefir fermentation base material and fruit juice, the mass ratio of the kefir fermentation base material to the fruit juice is (90-99): (1-10), wherein the total acid of the fruit juice is ≥1.0%; The kefir fermented product is prepared by a method comprising at least the following process: mixing the kefir fermented base material and the fruit juice, and placing the mixture at 20-30° C. for 4-10 hours to obtain the kefir fermented product.

2. The kefir fermented product according to claim 1, characterized in that The mass ratio of the kefir fermentation base material to the fruit juice is (92-98): (2-8).

3. The kefir fermented product according to claim 1 or 2, characterized in that The kefir fermentation base material and the fruit juice are mixed and placed at 25-30° C. for 6 hours to obtain the kefir fermentation product.

4. The kefir fermented product according to any one of claims 1 to 3, characterized in that The fruit juice comprises at least one of berry juice, stone fruit juice, melon fruit juice, pome fruit juice and citrus fruit juice.

5. The kefir fermented product according to claim 4, characterized in that The juice is prepared by a method comprising at least the following process: taking the edible part of the fruit and performing a juice extraction process to obtain the juice.

6. The kefir fermented product according to any one of claims 1 to 5, characterized in that The raw materials of the kefir fermentation base material include, by mass percentage, 30-90% of raw milk, 0-1% of a stabilizer, 4-13% of a sweetening substance, 0.001-0.1% of a kefir fermentation agent, and the balance being water.

7. The kefir fermented product according to claim 6, characterized in that The kefir fermentation base material is kefir fermented milk or kefir lactic acid bacteria beverage.

8. The kefir fermented product according to claim 7, characterized in that The kefir fermented milk is prepared by a method comprising at least the following steps: 1) adding the stabilizer, the sweetener and water to a first raw material system including the raw milk, and mixing them to obtain a first material; 2) homogenizing, sterilizing and cooling the first material in sequence to obtain a second material; 3) adding the kefir starter to the second material for fermentation, and terminating the fermentation when the acidity of the fermentation system reaches 70-80°T or the pH is less than 4.5 to obtain the kefir fermented milk; The kefir lactic acid bacteria beverage is prepared by a method comprising at least the following processes: 1) homogenizing the kefir fermented milk to obtain a third material; 2) diluting the second raw material system including the stabilizer and the sweetener with the water to obtain a fourth material; 3) The third material and the fourth material are mixed and homogenized to obtain the kefir lactic acid bacteria beverage.

9. A method for preparing a kefir fermented product according to any one of claims 1 to 8, characterized in that: The following steps are involved: 1) mixing the kefir fermentation base material and the fruit juice to obtain a mixed material; 2) placing the mixed material at 20-30° C. for 4-10 hours to obtain the kefir fermentation product.

10. The preparation method according to claim 9, characterized in that: Before step 2), the mixed material is also filled.

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