Double-layer double-color solidification type fermented milk and preparation method thereof

Abstract

The invention discloses double-layer double-color solidification type fermented milk and a preparation method thereof, and belongs to the technical field of dairy product processing. According to the preparation method of the double-layer double-color solidification type fermented milk, chlorella pyrenoidosa is added on the basis of traditional solidification type fermentation, and double-layer solidification type mixed fermentation is adopted. According to the double-layer double-color solidification type fermented milk disclosed by the invention, a coagulant and other additives do not need to be added, and a fermented product is good in texture, relatively good in solidification form and relatively small in whey precipitation by controlling a fermentation strain and the fermentation time of the fermentation strain.

Description

Technical Field

[0001] The invention relates to the technical field of dairy product processing, and more particularly to a double-layer and double-color coagulated fermented milk and a preparation method thereof. Background Art

[0002] Yogurt is divided into two types: stirred type and coagulated type, depending on whether it is fermented first and then canned or canned first and then fermented. Traditional coagulated fermented milk is a single form. With the development of the times, several types of layered coagulated yogurts have appeared, which can be divided into the following categories:

[0003] CN108112693A discloses a solidified layered multi-flavor yogurt and a preparation method thereof, wherein solidified yogurts of different flavors are separated by food films. During production, the yogurt needs to be filled first, and then the food film is placed on it, and then the solidified yogurt of another flavor is packaged on the food film to achieve yogurt layering.

[0004] CN101715823A discloses a skimmed layered yogurt and a preparation method thereof, wherein juice and / or jam are poured down along the side wall of a container by a four-head pouring method and spread on the fermented skimmed yogurt; or juice and / or jam are poured down along the side wall of a container by a four-head pouring method and poured under a fermentation tank to solidify the jam, and then yogurt is poured by a four-head pouring method, and finally a two-layered yogurt is obtained.

[0005] CN108576225A discloses a double-layer jam yogurt and a production process, comprising an upper base material layer and a lower jam layer, wherein the base material layer comprises yogurt and fruit particles; firstly, the raw materials of the jam layer are filled into the lower layer of a packaging container, cooled and solidified to form a jam layer, and then the raw materials of the base material layer in a can to be filled are filled into the packaging container to form an upper base material layer, thereby obtaining a double-layer jam yogurt, wherein a clear dividing line is maintained between the base material layer and the jam layer, so as to meet the flavor requirements of different consumers.

[0006] CN102812999A discloses a fruit-grain solidified yogurt and a preparation method thereof, wherein a suspended fruit-grain solidified yogurt is obtained by adjusting a yogurt formula.

[0007] However, the above existing methods all achieve the effect of layering by adding jam-like substances, and the form and taste are single. Currently, there is no coagulated yogurt with added pyrenoid chlorella on the market.

[0008] Therefore, providing a double-layer and double-color coagulated fermented milk and a preparation method thereof is an urgent problem to be solved by those skilled in the art. Summary of the invention

[0009] In view of this, the present invention provides a double-layered double-color coagulated fermented milk and a preparation method thereof, wherein the prepared double-layered double-color coagulated fermented milk is rich in marine and terrestrial proteins, has a special taste, and has a high protein content. The method of the present invention is different from the existing technology of achieving color difference stratification by adding juice or jam.

[0010] In order to achieve the above object, the present invention adopts the following technical solution:

[0011] A method for preparing double-layer and double-color coagulated fermented milk comprises the following steps

[0012] (1) removing the fishy smell from pyrenoid chlorella, washing it, mixing it with distilled water in a mass ratio of 1:5 to 15, stirring it evenly, and breaking the cell wall to obtain a crude extract of chlorella;

[0013] (2) separating the crude extract to obtain a precipitate and a supernatant a; adding distilled water in an amount equal to that of the supernatant a to the precipitate, stirring the mixture to obtain a supernatant b; mixing the supernatant a with the supernatant b to obtain a Chlorella extract;

[0014] (3) mixing skim milk and Chlorella extract in a mass ratio of 1:8 to 15 and sterilizing the mixture to obtain an algae green layer; sterilizing skim milk and obtaining a milky white layer;

[0015] (4) When the algae green layer is used as the lower layer, the milky white layer is used as the upper layer; when the milky white layer is used as the lower layer, the algae green layer is used as the upper layer;

[0016] (5) first canning the lower layer, adding the fermentation agent of the lower layer, and ending the fermentation after solidification, and refrigerating at 2 to 6 degrees Celsius to obtain the fermentation product of the lower layer;

[0017] (6) adding the fermentation agent of the upper layer to the upper layer and fermenting it separately, and pouring it onto the fermented product of the lower layer after the fermentation is completed;

[0018] (7) After a period of mixed fermentation, a double-layer, two-color coagulated fermented milk is obtained.

[0019] Furthermore, the method for removing the fishy smell of the protein-core Chlorella in step (1) is to use a 40% to 60% volume fraction ethanol aqueous solution for ultrasonic treatment for 20 to 40 minutes; the cell wall breaking method is a high-pressure homogenization method, and the homogenization pressure is 50 to 100 MPa.

[0020] Furthermore, the separation method in step (2) is centrifugal separation at 3500-4000 r / min and the centrifugation time is 10 minutes.

[0021] Furthermore, the lower fermentation agent in step (5) is a mixture of seed liquids of lactobacillus and thermophilic streptococci in the logarithmic growth phase, and the concentration of the seed liquid is 10 8CFU / mL, the ratio of the two is 1:(0.5-2), the inoculation amount is 1-3%; the fermentation conditions are 40-45 degrees Celsius, the fermentation time is 6-8 hours, and the pH is 4.5-5.0.

[0022] Further, the upper fermentation agent in step (6) is a mixture of seed liquid of lactobacillus and Lactobacillus bulgaricus in the logarithmic growth phase, and the concentration of the seed liquid is 10 8 CFU / mL, the ratio of the two is 1:(0.5-2), the inoculation amount is 1-3%; the fermentation conditions are 40-45 degrees Celsius, the fermentation time is 8-10 hours, and the pH is 4.8-5.3.

[0023] Furthermore, the fermentation condition in step (6) is 40 to 45 degrees Celsius, and the fermentation time is 2 to 4 hours.

[0024] Furthermore, the method described above can prepare double-layer and double-color coagulated fermented milk.

[0025] It can be known from the above technical scheme that compared with the prior art, the present invention discloses a double-layer two-color coagulation type fermented milk and a preparation method thereof. On the basis of the traditional coagulation type fermentation, protein nucleus chlorella is added to obtain a double-layer coagulation type mixed fermentation; the protein nucleus chlorella is pretreated and mixed with skim milk for sterilization to obtain an algae green layer, the skim milk is sterilized to obtain a milky white layer, one layer is canned and inoculated with a starter, and refrigerated after solidification, and the other layer is inoculated with a starter, and after fermentation for a period of time, it is poured into the lower layer, and the finished product can be obtained after fermentation for a period of time. The present invention adopts a double-layer coagulation type fermentation process to obtain a double-layer two-color feature that is different from most products on the market. After controlling the fermentation time, there is no obvious whey precipitation; it has the mellow fragrance of milk and the taste of the ocean, and has a high protein content.

[0026] The double-layer and double-color coagulated fermented milk of the present invention does not need to add additives such as coagulants. By controlling the fermentation bacteria and the fermentation time, the fermented product has good texture, better coagulation shape, and less whey precipitation. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying creative work.

[0028] Figure 1 The accompanying drawing is a schematic diagram of a finished product of a coagulated fermented milk having a milky white upper layer and an algae green lower layer according to the present invention;

[0029] Figure 2The accompanying drawing is a schematic diagram of a finished product of a coagulated fermented milk having an algae green upper layer and a milky white lower layer according to the present invention. DETAILED DESCRIPTION

[0030] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0031] Example 1

[0032] (1) mixing Chlorella pyrenoidosa and a 40% ethanol aqueous solution in a weight ratio of 1:10, and ultrasonically washing for 20 minutes;

[0033] (2) adding distilled water 20 times the mass of Chlorella vulgaris to the mixture after ultrasonication in step (1), centrifuging at 4000 r / min for 10 minutes, and discarding the supernatant;

[0034] (3) adding distilled water 20 times the mass of Chlorella vulgaris to the precipitate of step (2), stirring evenly, centrifuging at 4000 rpm for 10 minutes, and discarding the supernatant;

[0035] (4) adding distilled water 10 times the mass of Chlorella vulgaris to the precipitate of step (3), stirring evenly and then entering into a high-pressure homogenizer (homogenizing pressure 50 MPa) to obtain a crude extract of Chlorella vulgaris;

[0036] (5) Centrifuging the crude Chlorella extract obtained in step (4) at 4000 r / min for 10 minutes, retaining supernatant a; adding distilled water in an amount equal to that of supernatant a to the precipitate, stirring evenly, and centrifuging at 4000 r / min for 10 minutes to obtain supernatant b; combining supernatants a and b to obtain a Chlorella extract.

[0037] (6) The chlorella extract obtained in step (5) and skimmed milk are mixed in a mass ratio of 10:1 and then pasteurized to obtain a sterilized liquid.

[0038] (7) The thermophilic Streptococcus logarithmic growth period seed solution (10 8 CFU / mL and Lactobacillus logarithmic growth period seed solution (10 8 CFU / mL) in a ratio of 1:1, and inoculated into the sterilized liquid in step (6) at a rate of 2%, and fermented at 40°C for 8 hours, with a pH of 4.5.

[0039] The seed liquid of Lactobacillus bulgaricus in logarithmic growth period (10 8 CFU / mL and Lactobacillus logarithmic growth period seed solution (108 CFU / mL) in a ratio of 1:1, and inoculated into the sterilized liquid in step (6) at a rate of 2%, and fermented at 40°C for 8 hours, with a pH of 4.5.

[0040] The coagulation during the fermentation process, the texture properties after refrigeration for 8 hours after fermentation, and the number of live bacteria after refrigeration for 48 hours were measured. The results are shown in Tables 1-3.

[0041] Table 1 Coagulation changes with fermentation time

[0042]

[0043] Table 2 Texture characteristics

[0044]

[0045] Table 3 Number of viable bacteria

[0046]

[0047] Example 2

[0048] A method for preparing double-layer and double-color coagulable fermented milk comprises the following steps:

[0049] (1) mixing Chlorella pyrenoidosa and a 50% by volume ethanol aqueous solution in a weight ratio of 1:10, and ultrasonically washing for 30 minutes;

[0050] (2) adding distilled water 20 times the mass of Chlorella vulgaris to the mixture after ultrasonication in step (1), centrifuging at 3700 r / min for 10 minutes, and discarding the supernatant;

[0051] (3) adding distilled water 20 times the mass of Chlorella vulgaris to the precipitate of step (2), stirring evenly, centrifuging at 3700 r / min for 10 minutes, and discarding the supernatant;

[0052] (4) adding distilled water 10 times the mass of Chlorella vulgaris to the precipitate of step (3), stirring evenly and then entering into a high-pressure homogenizer (homogenization pressure of 75 MPa) to obtain a crude extract of Chlorella vulgaris;

[0053] (5) Centrifuging the crude Chlorella extract obtained in step (4) at 3700 r / min for 10 minutes, retaining supernatant a; adding distilled water in an amount equal to that of supernatant a to the precipitate, stirring evenly, and centrifuging at 3700 r / min for 10 minutes to obtain supernatant b; combining supernatants a and b to obtain a Chlorella extract.

[0054] (6) mixing the chlorella extract obtained in step (5) and skimmed milk in a mass ratio of 8:1 and pasteurizing the mixture to obtain an algae green layer; and sterilizing the skimmed milk to obtain a milky white layer;

[0055] (7) The algae green layer obtained in step (6) was filled, and then a mixture of thermophilic streptococci and lactobacillus logarithmic growth phase seed solution was added at a mass ratio of 2% (the concentration of both seed solutions was 10 8 CFU / mL, the ratio of the two was 1:1), and fermented at 42°C, pH 5.0 until coagulation (about 6h of fermentation).

[0056] (8) Refrigerate the green layer fermentation product obtained in step (7).

[0057] (9) The milky white layer after sterilization in step (6) was added with a mixture of Lactobacillus bulgaricus and Lactobacillus logarithmic growth phase seed solution at a mass ratio of 2% (the concentrations of the two seed solutions were both 10 8 CFU / mL, the ratio of the two was 1:1), and the fermentation was performed for 8 hours;

[0058] (10) pouring the fermented product of step (9) onto the solidified product of step (8);

[0059] (11) The double-layer product obtained in step (10) is fermented at 42° C. and the fermentation is stopped after 3 hours to obtain a final product, a double-layer and two-color coagulable fermented milk.

[0060] The product obtained in Example 2 is characterized by a lower layer of green and an upper layer of milky white, wherein the ratio of the two layers of color is 3:1 ( Figure 1 ).

[0061] Example 3

[0062] A method for preparing double-layer and double-color coagulable fermented milk comprises the following steps:

[0063] (1) Chlorella pyrenoidosa and a 60% ethanol aqueous solution were mixed in a weight ratio of 1:10, and ultrasonically washed for 40 minutes.

[0064] (2) adding distilled water 20 times the mass of Chlorella vulgaris to the mixture after ultrasonication in step (1), centrifuging at 3500 r / min for 10 minutes, and discarding the supernatant;

[0065] (3) adding distilled water 20 times the mass of Chlorella vulgaris to the precipitate of step (2), stirring evenly, centrifuging at 3500 r / min for 10 minutes, and discarding the supernatant;

[0066] (4) adding distilled water 10 times the mass of Chlorella vulgaris to the precipitate of step (3), stirring evenly and then entering into a high-pressure homogenizer (homogenization pressure of 100 MPa) to obtain a crude extract of Chlorella vulgaris;

[0067] (5) Centrifuging the crude Chlorella extract obtained in step (4) at 3500 r / min for 10 minutes, retaining supernatant a; adding distilled water in an amount equal to that of supernatant a to the precipitate, stirring evenly, and centrifuging at 3500 r / min for 10 minutes to obtain supernatant b; combining supernatants a and b to obtain a Chlorella extract.

[0068] (6) mixing the chlorella extract obtained in step (5) and skimmed milk in a mass ratio of 15:1 and pasteurizing the mixture to obtain an algae green layer; and sterilizing the skimmed milk to obtain a milky white layer;

[0069] (7) The milky white layer obtained in step (6) is filled, and then a mixture of thermophilic streptococci and lactobacillus logarithmic growth phase seed liquid is added at a mass ratio of 2% (the concentration of both seed liquids is 10 8 CFU / mL, the ratio of the two was 1:1), and fermented at 45°C, pH 5.0 until coagulation (fermentation for about 7h).

[0070] (8) refrigerating the milky white layer fermentation product obtained in step (7).

[0071] (9) The green algae layer sterilized in step (6) was added with a mixture of Lactobacillus bulgaricus and Lactobacillus logarithmic growth phase seed solution at a mass ratio of 2% (the concentrations of the two seed solutions were both 10 8 CFU / mL, the ratio of the two was 1:1), and the fermentation was performed for 8 hours;

[0072] (10) pouring the fermented product of step (9) onto the solidified product of step (8);

[0073] (11) The double-layer product obtained in step (10) is fermented at 42° C. and the fermentation is stopped after 3 hours to obtain a final product, a double-layer and two-color coagulable fermented milk.

[0074] The product obtained in Example 3 is characterized by a lower layer of white and an upper layer of green, wherein the ratio of the two layers of color is 3:2 ( Figure 2 ).

[0075] The above description of the disclosed embodiments enables one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for preparing double-layer and double-color coagulated fermented milk, characterized in that: The following steps are included (1) removing the fishy smell from the pyrenoid chlorella, washing it, mixing it with distilled water in a mass ratio of 1:5 to 15, stirring it evenly, and breaking the cell wall to obtain a crude extract of chlorella; (2) separating the crude extract to obtain a precipitate and a supernatant a; adding distilled water in an amount equal to that of the supernatant a to the precipitate, stirring the mixture to obtain a supernatant b; mixing the supernatant a with the supernatant b to obtain a Chlorella extract; (3) mixing skim milk and Chlorella extract in a mass ratio of 1:8 to 15 and sterilizing the mixture to obtain an algae green layer; sterilizing skim milk and obtaining a milky white layer; (4) When the algae green layer is used as the lower layer, the milky white layer is used as the upper layer; when the milky white layer is used as the lower layer, the algae green layer is used as the upper layer; (5) first canning the lower layer, adding the fermentation agent of the lower layer, and ending the fermentation after solidification, and refrigerating at 2 to 6 degrees Celsius to obtain the fermentation product of the lower layer; (6) adding the fermentation agent of the upper layer to the upper layer and fermenting it separately, and pouring it onto the fermented product of the lower layer after the fermentation is completed; (7) After a period of mixed fermentation, a double-layer, two-color coagulated fermented milk is obtained.

2. The method for preparing a double-layer and double-color coagulated fermented milk according to claim 1, characterized in that: The method for removing the fishy smell of the pyrenoid chlorella in step (1) is to use a 40% to 60% volume fraction ethanol aqueous solution for ultrasonic treatment for 20 to 40 minutes; the cell wall breaking method is a high-pressure homogenization method, and the homogenization pressure is 50 to 100 MPa.

3. The method for preparing a double-layer and double-color coagulated fermented milk according to claim 1, characterized in that: The separation method in step (2) is centrifugal separation at 3500-4000 r / min and the centrifugation time is 10 minutes.

4. The method for preparing a double-layer and double-color coagulated fermented milk according to claim 1, characterized in that: The lower fermentation agent in step (5) is a mixture of seed liquid of lactobacillus and thermophilic streptococcus in the logarithmic growth phase, and the concentration of the seed liquid is 10 8 CFU / mL, the ratio of the two is 1:(0.5-2), the inoculation amount is 1-3%; the fermentation conditions are 40-45 degrees Celsius, the fermentation time is 6-8 hours, and the pH is 4.5-5.

0.

5. The method for preparing double-layer and double-color coagulated fermented milk according to claim 1, characterized in that: The upper fermentation agent in step (6) is a mixture of seed liquid of lactobacillus and Lactobacillus bulgaricus in the logarithmic growth phase, and the concentration of the seed liquid is 10 8 CFU / mL, the ratio of the two is 1:(0.5-2), the inoculation amount is 1-3%; the fermentation conditions are 40-45 degrees Celsius, the fermentation time is 8-10 hours, and the pH is 4.8-5.

3.

6. The method for preparing double-layer and double-color coagulated fermented milk according to claim 1, characterized in that: The fermentation condition of step (6) is 40-45 degrees Celsius and the fermentation time is 2-4 hours.

7. Double-layer and double-color coagulated fermented milk prepared by the method according to any one of claims 1 to 6.

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