Method for producing fermented milk and fermented milk-like acidic gel

Abstract

To provide a novel method for producing acidic gel of milk that is highly versatile and has little effect on flavor, that is, to provide a fermented milk and a novel method for producing fermented milk-like acidic gel without going through a fermentation step.SOLUTION: Provided are a fermented milk and a method for producing a fermented milk-like acidic gel, and the method includes the following steps (1) to (4): (1) a step of providing a formulation milk; (2) a step of controlling the temperature of the formulation milk at 0 to 10°C; (3) a step of adjusting the pH of the formulation milk to 4.0 to 5.2; (4) a step of leaving pH-adjusted formulation milk at a temperature of 10 to 35°C.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a method for producing fermented milk and fermented milk-like acidic gels.

Background Art

[0002] Fermented milk is a food obtained by coagulating milk protein with an acid. Therefore, when producing fermented milk, lactic acid bacteria must be inoculated into raw milk, and a fermentation process for acid-coagulating the raw milk must be passed through. In particular, for set-type fermented milk, there are problems such as the need for a dedicated fermentation storage or cooler, and the need to secure a large space for temperature control. The following prior arts exist as methods for producing fermented milk-like acidic gels without using lactic acid bacteria or fermentation storage.

[0003] Patent Documents 1 and 2 disclose a method for producing an acid-coagulable milk food excellent in heat stability and physical properties by adjusting the pH of raw milk to 5.5 to 6.2 with citric acid or phosphoric acid and performing ultrafiltration treatment. Patent Document 3 discloses a method for acidifying and gelling milk by adding 0.3 to 0.6% glucono-delta-lactone to milk or soy milk and reacting it in a temperature range of 10 to 40°C. Patent Document 4 discloses a step of blending a citrate and a thickener in a raw material liquid containing milk components and adjusting the pH of the raw material liquid to a weakly acidic range of 5.1 to 6.5, and suppressing the aggregation of proteins in a weakly acidic gel-like milk processed product by setting the weight ratio of fat / protein in the raw milk to 1.8 or less. However, in Patent Documents 1, 2, and 3, the means of acidification are limited methods such as phosphoric acid, citric acid, glucono-lactone, etc. Further, in addition to the means of acidification being citric acid in Patent Document 4, it gels milk by the raw material composition and the blending of a thickener, so it is also a limited method. Furthermore, since these methods add specific components for acidification, there is a possibility that the composition and flavor will be different from those of fermented milk obtained by fermenting lactic acid bacteria.

Prior Art Documents

Patent Documents

[0004] [Patent Document 1] Japanese Patent Publication No. 2018-64482 [Patent Document 2] Japanese Patent Publication No. 2018-64481 [Patent Document 3] Patent No. 4827100 [Patent Document 4] Japanese Patent Publication No. 2017-55751 [Overview of the Initiative] [Problems that the invention aims to solve]

[0005] The present invention aims to provide a novel method for producing a milk acidic gel that is highly versatile and has minimal impact on flavor. Specifically, it aims to provide a novel method for producing fermented milk and a fermented milk-like acidic gel without going through a fermentation process. [Means for solving the problem]

[0006] The inventors of the present invention have diligently studied to solve the above problems and have found that the hardness of gel-like foods can be controlled by adjusting the milk protein to near its isoelectric point and by controlling the temperature within a predetermined range after the adjustment, thereby completing the present invention. In other words, the present invention includes the following steps. <1> A method for producing fermented milk and a fermented milk-like acidic gel, comprising the following steps: (1) Process of providing compounded milk (2) A process to control the temperature of the above-mentioned prepared milk to 0-10°C. (3) The process of adjusting the pH of the above-mentioned formula milk to 4.0-5.2 (4) The process of allowing the pH-adjusted formula milk to stand at a temperature of 10-35°C. The manufacturing method comprising the above. <2> The step of providing the prepared milk in step (1) above is a step of providing raw milk, skim milk, reconstituted milk, reconstituted skim milk, or milk to which auxiliary ingredients have been added. <1> The manufacturing method described above. <3> Furthermore, the following steps (5) are included. <1> or <2> The manufacturing method described above. (5) The process of adding one of lactic acid bacteria, bifidobacteria, and yeast, or a combination thereof, to the prepared milk as described in (1) to (4) above. <4> The step of adjusting the pH of the prepared milk in step (3) above to 4.0 to 5.2 is, This is a process that involves adjusting the solution using organic acids. <1> ~ <3> A manufacturing method described in any of the following. <5> It does not include the fermentation process. <1> ~ <4> A manufacturing method described in any of the following. <6> <1> ~ <5> Fermented milk and fermented milk-like acidic gel produced by the manufacturing method described in any of the above. <7> A method for gelling milk, comprising the step of adjusting the pH of the prepared milk at 0-10°C to 4.0-5.2, and then controlling the temperature of the prepared milk. <8> The process of controlling the temperature is a process of controlling it within the range of 10 to 35°C. <7> The method for gelling milk as described above. [Effects of the Invention]

[0007] According to this method, by adjusting the milk to near its isoelectric point and then controlling the temperature within a predetermined range, it is possible to provide fermented milk with a desired hardness and a fermented milk-like acidic gel. Furthermore, using lactic acid to adjust the isoelectric point has the advantage of not impairing the original flavor of the fermented milk. [Modes for carrying out the invention]

[0008] The manufacturing method of the present invention includes the following steps (1) to (4), and may also include step (5) as needed. Each step will be described below. Process (1): Process of providing prepared milk In the present invention, step (1) is the step of providing prepared milk. The compounded milk used in this invention can be any milk containing a protein that gels at its isoelectric point, such as raw milk, skim milk, reconstituted milk obtained by dissolving whole milk powder, reconstituted skim milk obtained by dissolving skim milk powder, or soy milk. Furthermore, any auxiliary ingredients may be added to these compounded milks. The auxiliary ingredients are not limited and can be selected as appropriate. Auxiliary ingredients can be added within the range that allows the compounded milk, which is the main ingredient, to gel. Examples of auxiliary ingredients include flavorings, fruits and vegetables, fruit and vegetable juices, fruit and vegetable extracts, ingredients containing nutrients, milk ingredients, functional ingredients, thickeners, emulsifiers, colorings, preservatives, and other food additives. Furthermore, raw milk and skim milk may be concentrated using a membrane or evaporator. It is also desirable to sterilize the compounded milk using a known sterilization method. Among these, it is preferable to heat sterilize by holding at 63°C for 30 minutes, or by a method having an equivalent or greater sterilization effect. In addition to the above, dairy ingredients include whole milk concentrate, skimmed milk concentrate, sweetened condensed milk, sweetened skimmed condensed milk, unsweetened condensed milk, unsweetened skimmed condensed milk, whey, whey powder, defatted whey, defatted whey powder, whey protein concentrate (WPC), whey protein isolate (WPI), α-lactalbumin, β-lactoglobulin, milk protein concentrate (MPC), casein, sodium caseinate, calcium caseinate, cream, fermented cream, compound cream, cream powder, butter, fermented butter, buttermilk, buttermilk powder, and butter oil. The protein content in the fermented milk and fermented milk-like acidic gel of the present invention is not particularly limited as long as it is sufficient to gel near the isoelectric point, but 1 to 20% by weight is preferred. More preferably 1 to 15% by weight, and most preferably 3 to 10% by weight.

[0009] Step (2): A step to control the temperature of the above-mentioned prepared milk to 0-10°C. In the present invention, step (2) is a step of adjusting the temperature of the formulated milk in step (1) to 0 to 10°C. Among these, it is preferable to adjust the temperature of the formulated milk to 0 to 5°C, and more preferably to 0 to 3°C. In the present invention, a step of preparing formulated milk that has been previously adjusted to 0 to 10°C is also regarded as a step including steps (1) and (2) of the present invention.

[0010] Step (3): A step of adjusting the pH of the above-mentioned formulated milk to 4.0 to 5.2 In the present invention, step (3) is a step of adjusting the pH of the formulated milk to 4.0 to 5.2. This is because hydrophobic interactions become stronger and proteins gel when the pH is near the isoelectric point. The isoelectric point varies depending on the type of protein, but in the present invention, it is 4.0 to 5.2, preferably 4.2 to 5.0, and more preferably 4.4 to 4.8. By adjusting the temperature of the formulated milk to 0 to 10°C in step (2), the aggregation rate of milk proteins is reduced, and it does not coagulate immediately even at the pH near the isoelectric point in step (3), maintaining a liquid state, enabling the transportation and filling of the formulated milk with adjusted pH. The pH adjustment can be to 4.0 to 5.2, and any acidic material that does not affect the desired flavor of the final product may be used, and it is preferable to adjust with an organic acid. Examples of organic acids include lactic acid, acetic acid, tartaric acid, etc. Among these, lactic acid is preferable because it does not affect the flavor of fermented milk or fermented milk-like acidic gels. The concentration, addition amount, and type of the acidic material are not limited and are appropriately determined so that the pH of the formulated milk can be adjusted to 4.0 to 5.2. As the acidic material, in addition to the above-mentioned organic acids, flavor components, fruit juices, vegetable juices, flavors, etc. may also be used.

[0011] Step (4): A step of controlling the temperature of the formulated milk with adjusted pH to 10 to 35°C and allowing it to stand In the present invention, step (4) is a step of adjusting the temperature of the formulated milk whose pH has been adjusted in step (3) to 10 to 35°C. If the temperature is less than 10°C, it is difficult to gel even after standing for a long time. If the temperature is higher than 35°C, although it gels, it lacks smoothness. Since the higher the temperature, the harder the gel obtained, and the lower the temperature, the softer the gel tends to be obtained, by changing the controlled temperature, it is possible to adjust the gel to the desired hardness. By allowing the formulated milk to stand after adjusting its temperature, a fermented milk-like acidic gel can be produced. By controlling the aggregation rate of milk proteins according to the temperature during standing of the formulated milk, the physical properties of the acidic gel are adjusted. Also, by adjusting the temperature during standing of the formulated milk to as low a temperature as possible, storage after the product is manufactured can be carried out simultaneously, and a large space required for temperature control such as a fermentation store can be reduced. Here, when commercializing fermented milk and fermented milk-like acidic gel in a state of being filled in a container, it is desirable to perform the filling into the container before standing. As an example of before the standing step, the following three patterns of sequences can be mentioned. Pattern 1. Step of providing the formulated milk (step (1) above) → Filling step → Temperature control step (step (2) above) → pH adjustment step (step (3) above) → Standing (step (4) above) Pattern 2. Step of providing the formulated milk (step (1) above) → Temperature control step (step (2) above) → Filling step → pH adjustment step (step (3) above) → Standing (step (4) above) Pattern 3. Step of providing the formulated milk (step (1) above) → Temperature control step (step (2) above) → pH adjustment step (step (3) above) → Filling step → Standing (step (4) above)

[0012] Step (5): In the above (1) to (4), a step of adding any one or a combination of lactic acid bacteria, bifidobacteria, and yeast to the formulated milk In the present invention, step (5) is a step of adding one or a combination of lactic acid bacteria, bifidobacteria, and yeast to the prepared milk in any of steps (1) to (4), as needed. The types of lactic acid bacteria, bifidobacteria, and yeast are not limited and can be selected as appropriate. Furthermore, the concentration and amount of lactic acid bacteria, bifidobacteria, and yeast added are not limited and can be determined as appropriate to produce the desired fermented milk or fermented milk-like acidic gel. In this invention, fermented milk refers to a product containing a certain number of viable bacteria and a certain amount of non-fat milk solids. In addition to the definition set forth in the Ministerial Ordinance on Standards for Ingredients of Milk and Dairy Products (Milk and Dairy Products Ordinance), any product containing 8.0% or more of non-fat milk solids and 10 million or more lactic acid bacteria (or yeast) per milliliter is included in the fermented milk of this invention. Furthermore, if the product is not manufactured as fermented milk, it is not necessary to add lactic acid bacteria, bifidobacteria, or yeast. In this invention, a fermented milk-like acidic gel refers to a fermented milk as defined above that does not contain the specified number of viable lactic acid bacteria (or yeast) or does not contain any of them. Thus, the manufacturing method of the present invention makes it possible to produce fermented milk or a fermented milk-like acidic gel without going through a fermentation process, in the same way as when it has gone through a fermentation process using lactic acid bacteria (or yeast).

[0013] The manufacturing method of the present invention is based on the above-described steps, but it goes without saying that other steps used in food manufacturing can be interposed between the above steps, or added before or after the above steps. Such processes include sterilization, filling into containers, and homogenization, and can be carried out either at the raw material stage or at the stage of the manufactured acidic gel.

[0014] The fermented milk and fermented milk-like acidic gel obtained by the manufacturing method of the present invention can be used as food as is. In particular, since the hardness of the gel can be controlled by controlling the pH and temperature, gel-like foods of desired hardness can be freely produced. Furthermore, like known fermented milk, it can be further processed to become other foods. Examples of such foods include desserts and dairy beverages.

[0015] The following describes some embodiments of the present invention in detail, but the present invention is not limited to these embodiments. [Examples]

[0016] [Evaluation Method for Acidic Gels] The evaluation method for the acidic gels produced in the following examples and comparative examples will be described below. (Method for measuring hardness) A texture analyzer (Stable Micro Systems, TA-XT plus) was used to measure the hardness of the acidic gel. A 16mm diameter cylinder was used as a jig, and the jig was inserted 10mm into the acidic gel at a speed of 1mm / sec. The load on the acidic gel was measured using a load cell.

[0017] (Sensory evaluation) The sensory evaluation of the acidic gel was conducted by a panel of sensory evaluation specialists. The panel consisted of four specialists who evaluated the smoothness of the acidic gel at a temperature of 10°C when eaten, using a two-point scale: "○: Smooth" and "×: Not smooth." The results are shown in Table 1 below, with "○" indicating that three or more people gave "○" and "×" indicating that two or fewer people gave "○."

[0018] [Example 1] Acidic gels were prepared under each condition, and their hardness was measured and sensory evaluation was performed. 1. Method for producing acidic gel The acidic gel was prepared using the following procedure. (i) Homogenized milk at a homogenization pressure of 15 MPa was immersed in hot water and pasteurized at 90°C for 10 minutes to prepare the prepared milk. Next, the pasteurized prepared milk was immersed in ice water and cooled to 10°C for adjustment. The solids content and casein:whey ratio of the prepared milk are shown in Table 1. (ii) 50g of the prepared milk was measured into a 100g capacity cup-type container and cooled to 3°C. (iii) The pH of the formula milk was adjusted to 4.7 using lactic acid (20 wt%). (iv) The pH-adjusted formula milk was left standing at 10°C for 20 hours. 2. Evaluation Results The hardness of the obtained acidic gel after 10 mm penetration was 11.7 gf. The sensory evaluation of the smoothness of the obtained acidic gel was "〇".

[0019] [Example 2] 1. Method for producing acidic gel (i)~(iii) Same as Example 1. (iv) pH-adjusted formula milk was left standing at 30°C for 20 hours. 2. Evaluation Results The hardness of the obtained acidic gel at a penetration depth of 10 mm was 37.5 gf, which was harder than the acidic gel obtained in Example 1. Therefore, it was found that the hardness of the acidic gel can be controlled by temperature control after pH adjustment. The sensory evaluation of the smoothness of the obtained acidic gel was "○".

[0020] [Example 3] 1. Method for producing acidic gel (i)~(ii) Same as Example 1. (iii) The pH of the formula milk was adjusted to 4.7 using acetic acid (50 wt%) to prepare the pH. (iv) Same as Example 1. 2. Test Results The hardness of the obtained acidic gel after 10 mm penetration was 11.0 gf. Furthermore, an acidic gel with almost the same hardness as in Example 1 was obtained, indicating that the difference in organic acids had little effect on the hardness of the acidic gel. The sensory evaluation of the smoothness of the obtained acidic gel was "○".

[0021] [Comparative Example 1] 1. Method for producing acidic gel (i)~(iii) Same as Example 1. (iv) pH-adjusted formula milk was left standing at 5°C for 20 hours. 2. Evaluation Results Even after standing, the prepared milk remained liquid and did not gel.

[0022] [Comparative Example 2] 1. Method for producing acidic gel (i)~(iii) Same as Example 1. (iv) pH-adjusted formula milk was left standing at 40°C for 20 hours. 2. Evaluation Results The hardness of the obtained acidic gel after 10 mm penetration was 78.7 gf. The sensory evaluation of the smoothness of the obtained acidic gel was "×".

[0023] [Comparative Example 3] 1. Method for producing acidic gel (i) and (ii) are the same as in Example 1. (iii) The pH was adjusted to 5.5 using lactic acid (20 wt%). (iv) pH-adjusted formula milk was left standing at 30°C for 20 hours. 2. Evaluation Results Even after standing, the prepared milk remained liquid and did not gel.

[0024] [Table 1]

[0025] [Consideration] Table 1 summarizes the manufacturing conditions and evaluation results for each of the above acidic gels. A comparison of Example 1 and Example 2 revealed that hardness can be controlled by temperature control after pH adjustment, and that higher control temperatures tend to yield acidic gels with higher hardness. Furthermore, from Comparative Examples 1 and 2, it was found that gelation did not occur at 5°C, and smoothness was lacking at 40°C. Therefore, the temperature range for step (4) of the present invention is greater than 5°C and less than 40°C, and 10°C to 35°C is preferred. Furthermore, Example 3 showed that the same effect can be obtained by changing the type of organic acid used to adjust the pH in step (3). Furthermore, since gelation was not possible when the pH of the prepared milk was set to 5.5, as shown in Comparative Example 3, it was found that the pH range adjusted in step (3) of the present invention must be near the isoelectric point, and 4.0 to 5.2 is desirable. Furthermore, it was found that a temperature of 10°C or lower is desirable for step (2) in order to reduce the aggregation rate of milk proteins and prevent immediate coagulation even at pH levels near the isoelectric point. [Industrial applicability]

[0026] According to the manufacturing method of the present invention, by adjusting the milk to near its isoelectric point and controlling the temperature within a predetermined range after the adjustment, it is possible to provide fermented milk and a fermented milk-like acidic gel with a desired hardness. Furthermore, by using lactic acid to adjust the isoelectric point, it is possible to provide fermented milk and a fermented milk-like acidic gel without impairing the original flavor of the fermented milk.

Claims

1. A method for producing fermented milk and a fermented milk-like acidic gel, comprising the following steps: (1) Process of providing compounded milk (2) A process to control the temperature of the above-mentioned prepared milk to 0-10°C. (3) A step to adjust the pH of the above-mentioned formula milk to 4.0 to 5.

2. (4) The process of letting the pH-adjusted formula milk stand at a temperature of 10 to 35°C. The manufacturing method comprising the above.

2. The manufacturing method according to claim 1, wherein the step of providing the prepared milk in step (1) is a step of providing raw milk, skim milk, reconstituted milk, reconstituted skim milk, or milks to which auxiliary ingredients have been added.

3. The manufacturing method according to claim 1 or 2, further comprising the following step (5). (5) The step in (1) to (4) above, of adding one of lactic acid bacteria, bifidobacteria, and yeast, or a combination thereof, to the prepared milk.

4. The step of adjusting the pH of the prepared milk in step (3) above to 4.0 to 5.2 is, The manufacturing method according to any one of claims 1 to 3, wherein the step is to adjust using an organic acid.

5. A manufacturing method according to any one of claims 1 to 4, which does not include a fermentation step.

6. A method for gelling milk, wherein the pH of the prepared milk at 0-10°C is adjusted to 4.0-5.2, A method for gelling milk, including a step of controlling the temperature of the prepared milk.

7. The method for gelling milk according to claim 6, wherein the step of controlling the temperature is a step of controlling it within the range of 10 to 35°C.

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