JP7746033B2 - Fermented milk and its manufacturing method - Google Patents

Description

Following the notification of the functional food claim application under Article 30, Paragraph 2 of the Patent Act, Notification Number F279 (notification date: July 16, 2020), the information was posted on the website (URL: https://www.fld.caa.go.jp/caaks/cssc07/hyoji_mihon?hyojimihonFile＝F279%255CF279_hyoji_mihon.pdf).

Following the notification of the functional food claim application under Article 30, Paragraph 2 of the Patent Act, Notification Number F458 (notification date: September 15, 2020), the information was posted on the website (URL: https://www.fld.caa.go.jp/caaks/cssc07/hyoji_mihon?hyojimihonFile＝F458%255CF458_hyoji_mihon.pdf).

The present invention relates to a method for producing fermented milk containing a gelling agent, and to fermented milk containing a gelling agent. The present invention also relates to a method for imparting hardness to fermented milk.

When microorganisms such as lactic acid bacteria and yeast are added to the raw milk and kept at a certain temperature, the microorganisms multiply. This results in fermented milk, such as yogurt.
If fermented milk does not have sufficient hardness, its structure may collapse during transportation. Therefore, in order to impart hardness to fermented milk, additives such as stabilizers containing polymeric compounds such as agar, starch, and gelatin have generally been used. In addition, a manufacturing method for obtaining fermented milk that has a hardness that can withstand vibration during distribution and that suppresses whey separation and increases in acidity has also been reported (Patent Document 1).

Milk protein hydrolysates (milk peptides) are produced by treating proteins contained in milk with enzymes to reduce their molecular weight. Milk protein hydrolysates are widely used to prevent food allergies caused by milk or dairy products, and as a peptide raw material.

Japanese Patent Application Publication No. 10-99019

The inventors attempted to produce fermented milk containing a milk protein hydrolysate and a gelling agent. They found that the hardness of the fermented milk containing a milk protein hydrolysate and a gelling agent did not increase even after the fermentation process, despite the addition of the gelling agent. If the hardness after the fermentation process is low, the structure may break down during transportation, significantly reducing the value of the fermented milk as a product.

The inventors conducted extensive research to solve the above-mentioned problems. They discovered that by adjusting the pH of a raw material mixture solution containing a milk protein hydrolysate to 6.7 to 7.4 during sterilization, it is possible to impart hardness to gelling agent-containing fermented milk, leading to the completion of the present invention.

That is, the present invention has the following configuration.
<1>
A method for producing gelling agent-containing fermented milk, comprising a sterilization step of a raw material mixture solution containing a milk protein hydrolysate, wherein the pH of the raw material mixture solution in the sterilization step is 6.7 to 7.4.
<2>
The method for producing gelling agent-containing fermented milk according to <1>, wherein the gelling agent is agar.
<3>
The method for producing gelling agent-containing fermented milk according to <1> or <2>, wherein the milk protein hydrolysate is a whey protein hydrolysate.
＜4＞
<1> - <3> The method for producing gelling agent-containing fermented milk according to any one of <1> to <3>, wherein the content of the milk protein hydrolysate is 0.1% by weight to 3.0% by weight based on the fermented milk, and the content of the gelling agent is 0.01% by weight to 0.3% by weight based on the fermented milk.
<5>
<4> The method for producing gelling agent-containing fermented milk according to any one of <1> to <4>, wherein the fermented milk has a hardness of 18 g f to 70 g f at 10°C after refrigerated storage for one day after production.
＜6＞
A fermented milk containing a milk protein hydrolysate and a gelling agent, the fermented milk having a hardness of 18 g f to 70 g f at 10°C after refrigerated storage for one day after production.
＜７＞
A fermented milk containing a milk protein hydrolysate and a gelling agent, the fermented milk having a hardness of 18 g f to 70 g f at 10°C at any time up to 18 days after production and refrigerated storage.
＜8＞
A method for imparting hardness to fermented milk in the production of fermented milk containing a milk protein hydrolysate and a gelling agent, comprising:
A method for imparting hardness to fermented milk, comprising a step of adjusting the pH of a raw material mixture solution containing a milk protein hydrolysate to 6.7 to 7.4 before sterilization.

According to the present invention, it is possible to impart an appropriate hardness to fermented milk containing a milk protein hydrolysate and a gelling agent after the fermentation process.

The present invention is described in detail below. While the present specification explains the invention in terms of its various aspects, the details, definitions, and embodiments described for each aspect are also applicable to the other aspects.

1. Fermented milk production method (fermented milk)
Fermented milk is defined in the "Ministerial Ordinance on Milk, etc." as a product made by fermenting milk or milk containing an equivalent or greater amount of non-fat milk solids with lactic acid bacteria or yeast into a paste or liquid, or a frozen version of these. In this specification, the definition of "fermented milk" as defined in the Ministerial Ordinance on Milk, etc. applies.
The fermented milk produced by the production method of the present invention may be either static fermented milk or stirred fermented milk, but static fermented milk is preferred.
In this specification, static fermented milk (also called post-fermented fermented milk, plain yogurt, hard yogurt, or set yogurt) refers to fermented milk that is filled into a drinking container with fermentation ingredients and then post-fermented. That is, it is fermented milk that is filled into a drinking container with fermentation ingredients, fermented, and then sold commercially without stirring. Static fermented milk prepared from fermentation ingredients that have been dissolved to achieve a high protein content or that have been previously concentrated using a membrane device or the like is also called concentrated fermented milk (Greek yogurt).
Stirred fermented milk (pre-fermented fermented milk) is produced by fermenting milk in advance in a manufacturing facility, crushing the resulting curd, mixing it with auxiliary ingredients such as sugar, flavoring, fruit juice, and fruit pulp, and then filling it into containers.

(Mixing process)
The method for producing fermented milk of the present invention can include a mixing step as an optional step. In this specification, the "mixing step" refers to a step of mixing and dissolving a milk protein hydrolysate, a gelling agent, and/or optional components to obtain a raw material mixture solution. Optional components include dairy products such as raw milk, concentrated skim milk, cream, butter, whole milk powder, skim milk powder, and whey powder, milk proteins, sweeteners, stabilizers, flavorings, etc. The dissolving liquid used for dissolution is not limited as long as the effects of the present invention are obtained, but water is preferred, and warm water is more preferred. The temperature of the warm water can be adjusted as appropriate. The raw material mixture solution preferably contains 8% to 20% by weight of non-fat milk solids.
In the mixing step, in consideration of the effects of the present invention described below, it is preferable to dissolve a milk raw material whose proteins are not decomposed in addition to the milk protein hydrolysate. "Milk raw material whose proteins are not decomposed" means a material that contains milk protein and the milk protein has not been decomposed by enzymes, etc., such as raw milk, skim milk, whey, and processed products thereof (whole milk powder, whole fat concentrated milk, skim milk powder, desalted skim milk powder, skim milk concentrated milk, condensed milk, whey powder, whey concentrated powder, cream, butter, cheese, etc.).

As long as the effects of the present invention can be obtained, the raw materials may be dissolved in a dissolving solution and then mixed, or the raw materials may be mixed and then dissolved in a dissolving solution. If necessary, it is preferable to use an appropriate dissolving machine, such as a power blender, a mixer, or a high-speed stirrer.
The milk raw material solution, such as the milk protein hydrolysate and skim milk powder, and the gelling agent solution may be sterilized separately and then mixed together, or both may be contained in the raw material mixed solution and sterilized together, but it is preferred that both be contained in the raw material mixed solution and sterilized together.

(Milk protein hydrolysate (milk peptide))
As used herein, "milk protein hydrolysate" refers to milk protein whose molecular weight has been reduced by the action of an enzyme. The milk protein hydrolysate used in the present invention is not particularly limited as long as the effects of the present invention can be obtained, and any of casein protein hydrolysate, whey protein hydrolysate, and mixtures thereof can be used, with whey protein hydrolysate being preferred. Methods for producing milk protein hydrolysates from milk proteins contained in milk or dairy products include, for example, acid hydrolysis, alkali hydrolysis, and enzymatic hydrolysis. The milk protein hydrolysate may be commercially available or may be prepared by the user.
For example, a whey protein hydrolysate having the following composition and properties can be used.
The total amount of BCAA, i.e., valine, leucine, and isoleucine, is 15% by weight or more, preferably 20% by weight or more, more preferably 21% by weight or more, based on the whey protein hydrolysate. The average molecular weight (MNV) is 200 Da to 500 Da, preferably 300 Da to 500 Da.
In the present invention, the amount of the milk protein hydrolysate blended with the raw material mixture solution or fermented milk is, for example, 0.1% by weight to 3.0% by weight, 0.2% by weight to 2.5% by weight, 0.3% by weight to 2.4% by weight, 0.5% by weight to 2.2% by weight, 0.8% by weight to 2.2% by weight, 1.0% by weight to 2.2% by weight, or 1.5% by weight to 2.2% by weight, based on the fermented milk, but is not limited to the following.

(Gelling Agent)
In this specification, the term "gelling agent" refers to a substance added to make a liquid solid or semi-solid, and is also called a thickener. The gelling agent used in the present invention is not particularly limited as long as the effects of the present invention can be obtained, and for example, at least one selected from agar, pectin, carrageenan, gellan gum, gelatin, xanthan gum, locust bean gum, guar gum, guar gum hydrolyzate, tara gum, alginic acid, and sodium alginate can be used. The use of agar or gelatin is preferred.
In the present invention, the amount of gelling agent added to the raw material mixture solution or fermented milk is, for example, 0.01% by weight to 0.3% by weight, 0.01% by weight to 0.25% by weight, 0.01% by weight to 0.2% by weight, 0.01% by weight to 0.18% by weight, 0.02% by weight to 0.18% by weight, 0.03% by weight to 0.18% by weight, 0.05% by weight to 0.18% by weight, 0.07% by weight to 0.18% by weight, 0.1% by weight to 0.18% by weight, 0.12% by weight to 0.18% by weight, or 0.12% by weight to 0.16% by weight, based on the fermented milk, but is not limited to the following.
The type and concentration of the gelling agent can be appropriately selected depending on the type and concentration of the milk protein hydrolysate, the type of fermented milk, etc.
When the gelling agent is agar, the jelly strength of the agar is, but is not limited to, for example, 100 g/cm ² to 2000 g/cm ² , 200 g/cm 2 to 1500 g/cm ² , 300 g/cm ² to 1200 g/cm ² , 400 g/cm ² to 1000 g/cm ² , or 500 g/cm ² to 900 g/cm ² as measured by ^the Nikkansui method.

(Step of heating and homogenizing the raw material mixture solution)
The method for producing fermented milk of the present invention can include, as an optional step, a step of heating and homogenizing the raw material mixture solution. The step of heating and homogenizing the raw material mixture solution is a step in which the raw material mixture solution is preheated to increase the homogenization efficiency, and then homogenized using a homogenizer or the like. Homogenization means finely breaking down fat globules in the milk fat and other raw materials to make them stable.
Prior to homogenization, the raw material mixture solution is preferably heated to 50°C to 85°C. The raw material mixture solution preferably contains a milk protein hydrolysate and a gelling agent, and these are homogenized together. The homogenization pressure may be the same as that used for ordinary fermented milk, and is, for example, 10 MPa to 20 MPa, preferably 12 MPa to 18 MPa.

(sterilization process)
The method for producing fermented milk of the present invention includes a sterilization step of a raw material mixture solution containing a milk protein hydrolysate. As used herein, the term "sterilization step" refers to treating the raw material mixture solution at a high temperature to reduce the number of microorganisms in the raw material mixture solution.
In the method for producing fermented milk of the present invention, the pH of the raw material mixture solution in the sterilization step is 6.7 to 7.4. If the pH is below 6.7, hardness will not be imparted to the fermented milk even after the fermentation step. On the other hand, if the pH exceeds 7.4, aggregation or separation may occur in the raw material mixture solution after sterilization.
When a milk protein hydrolysate is added to a raw material mixture solution, the pH of the raw material mixture solution tends to decrease. When producing fermented milk containing a milk protein hydrolysate, the pH of the raw material in the sterilization step is, for example, pH 6.6. On the other hand, in the present invention, the pH of the raw material mixture solution in the sterilization step is 6.7 to 7.4, more preferably 6.7 to 7.2, and even more preferably 6.8 to 7.1.

(pH adjustment)
If the pH of the raw material mixture solution before sterilization is outside the range of 6.7 to 7.4, the pH is adjusted. In this case, the timing of adjusting the pH is not limited as long as the effects of the present invention are obtained, and the adjustment may be performed during mixing and dissolution of the raw materials, or after preparation of the raw material mixture solution and before the sterilization step. It is preferable to adjust the pH after preparation of the raw material mixture solution and before the sterilization step. Specifically, it is preferable to continuously mix the pH adjuster with the raw material mixture in the piping before sterilization using a static mixer, or to add the pH adjuster to a tank containing the raw material mixture before sterilization and stir and dissolve it. Alternatively, a combination of these may be used.
The pH may be adjusted using a pH adjuster, food additive, food, or combination thereof that is generally used to adjust the pH of foods, such as potassium carbonate, sodium carbonate, sodium bicarbonate, trisodium citrate, sodium hydroxide, lactic acid, hydrochloric acid, glucono-delta-lactone, or lemon juice, or by adding a fermented product that has been previously fermented with one or more types of lactic acid bacteria and/or yeast.

(sterilization conditions)
The sterilization temperature and time are not limited as long as they correspond to the conditions used in ordinary fermented milk production, such as the LTLT method in which heating is performed at 60°C to 65°C for approximately 30 minutes, the HTLT method in which heating is performed at 75°C to 90°C for 15 to 60 minutes, the HTST method in which heating is performed at 70°C to 90°C for 15 to 60 seconds, or the UHT method in which heating is performed at 120°C to 150°C for 1 to 3 seconds. The sterilization apparatus used may be, for example, a plate heat exchanger, a tube sterilizer, direct steam injection, direct steam infusion, a thermocylinder, a rotatherm, a kettle emulsifying apparatus, a Stephan emulsifying apparatus, a Joule heating apparatus, a batch sterilization apparatus using a tank, or a combination thereof, and are not limited as long as they can be used in fermented milk production.
In the present invention, after sterilization, the raw material mixture solution may be cooled to a predetermined temperature. Specifically, for example, it may be cooled to a temperature close to the fermentation temperature in the fermentation step described below.

(Filling process)
When producing static fermented milk (post-fermented fermented milk), after the sterilization step, the milk can be filled into an appropriate container. The container can be a cup-shaped container made of paper or plastic with a paper, aluminum, or plastic lid.

(Fermentation process)
In this specification, the "fermentation step" refers to a step of fermenting a raw material mixture solution using a starter. Examples of starters to be added to and mixed (inoculated) with the raw material mixture solution include one or more starters selected from lactobacilli such as Lactobacillus bulgaricus, Lactobacillus lactis, Lactobacillus casei, and Lactobacillus paracasei, lactococci such as Streptococcus thermophilus, and other lactic acid bacteria and yeasts commonly used in the production of fermented milk.
The amount of starter added can be appropriately set according to the amount used in known methods for producing fermented milk. The method for inoculating the starter is also not particularly limited, and any method commonly used in the production of fermented milk can be used as appropriate. When multiple types of microorganisms are used for fermentation, the order in which these microorganisms are inoculated into the raw material mixture solution is not particularly important, and all of them may be added simultaneously. Any of these microorganisms may be inoculated multiple times.
Fermentation conditions can be set appropriately taking into consideration the type of fermented milk, the desired flavor, the type of starter used, etc. For example, a method can be used in which the temperature in a fermentation chamber (fermentation temperature) is maintained in the range of 30°C to 50°C, and the fermentation is carried out while the milk is left standing in the fermentation chamber. Such temperature conditions generally facilitate the activity of lactic acid bacteria, allowing fermentation to proceed effectively. The fermentation temperature is usually about 30°C to 50°C, preferably in the range of 35°C to 45°C, and more preferably in the range of 37°C to 43°C.
The fermentation time can be adjusted appropriately, with the aim of the lactic acid acidity of the fermented milk reaching a predetermined ratio, but is usually about 3 to 24 hours, or usually about 4 to 18 hours. The fermentation time can also be determined based on the final acidity or final pH. Specifically, fermentation can be stopped after the pH of the fermented milk reaches 4.0 to 5.0. After fermentation, it is preferable to cool the fermented milk to a temperature of 10°C or lower. Rapid cooling from the culture temperature to 10°C is preferably carried out within 10 hours, more preferably within 5 hours, even more preferably within 3 hours, and particularly preferably within 1 hour.

When the fermented milk produced by the production method of the present invention is stirred fermented milk, the production method of the present invention may include steps necessary for producing these types of fermented milk after the fermentation step. Examples of necessary steps include a crushing step in which curds are crushed by stirring after the fermentation step, a step in which solids or other ingredients such as fruit pulp or fruit preserves are added, and a step in which the solids or other ingredients are stirred with the fermented milk to homogenize it.

The production method of the present invention can include a concentration step before or after the fermentation step. Concentration methods include membrane concentration and centrifugation.

(effect)
The reason why the manufacturing method of the present invention is effective is not completely understood, but can be inferred as follows: However, the present invention is not limited to the following explanation.
In fermented milk, proteins bond together during fermentation, imparting hardness. However, if heat-denatured milk protein hydrolysates are present during fermentation, it is believed that the bond between proteins is inhibited. Furthermore, if the pH of the solution during sterilization is made closer to acidic, it is believed that the heat-denatured milk protein hydrolysates contained in the solution are more likely to be denatured. Therefore, by making the pH of the solution during sterilization closer to neutral, it is possible to prevent the heat-denatured milk protein hydrolysates from inhibiting the bond between proteins during fermentation.
Furthermore, if the pH is too high, aggregation and/or separation may occur in the raw material mixture solution containing the milk protein hydrolysate.

2. Fermented milk (raw material)
The fermented milk of the present invention can contain raw milk, skim milk, whey, etc., as well as processed products thereof (e.g., whole milk powder, whole fat concentrated milk, skim milk powder, desalted skim milk powder, skim milk concentrated milk, condensed milk, whey powder, whey concentrated powder, cream, butter, cheese, etc.). In addition to milk components, the fermented milk of the present invention can also contain foods or food ingredients and food additives such as sugar, sugars, sweeteners, flavorings, fruit juice, fruit pulp, vitamins, minerals, vegetable oils and fats, and emulsifiers. Furthermore, the raw materials for the fermented milk can contain stabilizers, starch, modified starch, dextrin, etc., as necessary.

(hardness)
Taking into consideration flavor, such as texture, smoothness of texture, and durability during product transportation, the hardness of the fermented milk of the present invention can be 18 g f to 70 g f , 20 g f to 60 g f , 20 g f to 50 g f , 20 g f to 45 g f , 22 g f to 40 g f , 25 g f to 40 g f, or 25 g f to 35 g f after refrigerated storage for one day after production.
Taking into consideration flavor and smoothness of texture, such as feel on the tongue, the hardness of the fermented milk of the present invention can be 20 g f to 70 g f , 20 g f to 60 g f, 20 g f to 50 g f, 20 g f to 45 g f, 22 g f to 40 g f , 25 g f to 40 g f , or 25 g f to 35 g f at any time point up to 18 days after production (i.e., 1, 2, 3 , 4 , 5, 6, 7 , 8, 9, 10, 11, 12, 13 , 14, 15 , 16, 17, or 18 days after production), and preferably 20 g f to 70 g f, 20 g f to 60 g f , 20 g f to 50 g f , or 20 g f to 45 g f at 7 days after production. , 22g f to 40g f , 25g f to 40g f , or 25g f to 35g f .

(Method of measuring hardness)
The method for measuring hardness in the present invention is as follows.
The hardness is measured using a creep meter (manufactured by Yamaden Co., Ltd.) Specifically, a plunger with a diameter of 15 mm is inserted into each sample (10°C) filled in a 100 ml container at a rate of 1 mm/sec, and the stress (g f ) at the point 1 cm into the plunger is measured and used as the hardness.

In this specification, "one day after refrigerated storage after production" means the day after the raw material mixed solution is filled into a container. "One day after refrigerated storage after production" may be referred to as D+1. That is,
The raw material mixture solution is filled into the container, and the day on which fermentation is started is set as day 0 in the calculation.

The non-fat milk solids content of the fermented milk of the present invention is, for example, 8.0% to 20% by weight, 8.0% to 15% by weight, 8.0% to 12% by weight, 8.0% to 10% by weight, or 8.0% to 9.5% by weight.
The milk fat content of the fermented milk of the present invention is, for example, 0.5% to 3.0% by weight, 0.5% to 2.5% by weight, 1.0% to 2.2% by weight, or 1.5% to 2.0% by weight.
The total solids content of the fermented milk of the present invention is, for example, 10% to 30% by weight, 12% to 27% by weight, 15% to 25% by weight, or 18% to 22% by weight.
The pH of the fermented milk of the present invention is, for example, 4.0 to 5.0, 4.1 to 4.9, 4.2 to 4.8, or 4.3 to 4.7.

3. Method for imparting hardness to fermented milk The method for imparting hardness to fermented milk of the present invention includes a step of adjusting the pH of a raw material mixture solution containing a milk protein hydrolysate and a gelling agent to 6.7 to 7.4 before sterilization.
As used herein, "imparting hardness" or "imparting hardness" means imparting sufficient hardness to fermented milk after fermentation so that the structure does not collapse even after transportation. Specifically, "imparting hardness" or "imparting hardness" means imparting a hardness of 18 g f or more to fermented milk one day after refrigerated storage after production.

The present invention will be explained in more detail below using examples, but the present invention is not limited thereto. Unless otherwise specified, % indicates % by weight. Jelly strength is measured using the Nikkansui method.

Example 1
9% skim milk powder, 0.15% agar with a jelly strength of 700 g / cm ² , 8% sugar, 3.5% cream with a 50% milk fat content, 1.7% milk protein enzymatic hydrolyzate HW-3 (manufactured by Megmilk Snow Brand Co., Ltd.: BCAA total 22.3%, number average molecular weight (MNV) approximately 400 Da) was dissolved in water to obtain an aqueous solution, adjusted to pH 6.9 using a pH adjuster, and then heated to 80 ° C. in a plate-type sterilizer, homogenized at a homogenizing pressure of 15 MPa in a homogenizer, sterilized at 120 ° C. for 3 seconds in a plate-type sterilizer, and then cooled to 45 ° C. Then, DVS lactic acid bacteria starter for yogurt production (mixed starter of Lactobacillus bulgaricus and Streptococcus thermophilus) was added and mixed to 200 U / 1000 kg. The mixture was filled into paper cup-shaped containers (90 g each) and aluminum lids were sealed with irons. Fermentation was then carried out in an incubator at 41°C, and when the pH reached 4.6, the mixture was transferred to an incubator at 5°C to stop the fermentation. The next day, the mixture was transferred to an incubator at 10°C to obtain Example Product 1. Example Product 1 had a non-fat milk solids content of 8.7%, a milk fat content of 1.8%, and a total solids content of 20.0%.
The milk protein enzymatic hydrolysate HW-3 used is a whey protein hydrolysate and has the following properties:
- The total amount of BCAA, i.e., valine, leucine, and isoleucine, is 15% by weight or more, preferably 20% by weight or more, and more preferably 21% by weight or more, based on the whey protein hydrolysate.
- Average molecular weight (MNV) of 200 Da to 500 Da, preferably 300 Da to 500 Da.

Example 2
Example Product 2 was obtained in the same manner as in Example 1, except that an aqueous solution was prepared by dissolving 9% skim milk powder, 0.15% agar with a jelly strength of 700 g/ ^cm² , 8% sugar, 3.5% cream with a 50% milk fat content, and 1.7% enzymatically hydrolyzed milk protein HW-3 (manufactured by Megmilk Snow Brand Co., Ltd.) in water, and the pH was adjusted to 6.7 using a pH adjuster.

Example 3
Example Product 3 was obtained in the same manner as in Example 1, except that an aqueous solution was prepared by dissolving 9% skim milk powder, 0.15% agar with a jelly strength of 700 g/ ^cm2 , 8% sugar, 3.5% cream with a 50% milk fat content, and 1.7% enzymatically hydrolyzed milk protein HW-3 (manufactured by Megmilk Snow Brand Co., Ltd.) in water, and the pH was adjusted to 7.2 using a pH adjuster.

Example 4
Example Product 4 was obtained in the same manner as Example 1, except that 9% skim milk powder, 0.15% agar with a jelly strength of 700 g/ ^cm2 , 8% sugar, 3.5% cream with a 50% milk fat content, and 0.5% milk protein enzymatic hydrolysate HW-3 (manufactured by Megmilk Snow Brand Co., Ltd.) were dissolved in water.

Example 5
Example Product 5 was obtained in the same manner as in Example 1, except that 9% skim milk powder, 0.15% agar with a jelly strength of 700 g/ ^cm2 , 8% sugar, 3.5% cream with a 50% milk fat content, and 2.2% milk protein enzymatic hydrolysate HW-3 (manufactured by Megmilk Snow Brand Co., Ltd.) were dissolved in water.

Example 6
Example Product 6 was obtained in the same manner as Example 1, except that 9% skim milk powder, 0.05% agar with a jelly strength of 700 g/ ^cm2 , 8% sugar, 3.5% cream with a 50% milk fat content, and 1.7% milk protein enzymatic hydrolysate HW-3 (manufactured by Megmilk Snow Brand Co., Ltd.) were dissolved in water.

Example 7
Example Product 7 was obtained in the same manner as in Example 1, except that 9% skim milk powder, 0.18% agar with a jelly strength of 700 g/ ^cm2 , 8% sugar, 3.5% cream with a 50% milk fat content, and 1.7% milk protein enzymatic hydrolysate HW-3 (manufactured by Megmilk Snow Brand Co., Ltd.) were dissolved in water.

(Example 8)
Example Product 8 was obtained in the same manner as Example 1, except that skim milk powder was dissolved in water to a concentration of 16%, agar with a jelly strength of 700 g/ ^cm² to a concentration of 0.05%, sugar to a concentration of 8%, cream with a milk fat content of 50% to a concentration of 3.5%, and milk protein enzymatic hydrolysate HW-3 (manufactured by Megmilk Snow Brand Co., Ltd.) to a concentration of 1.7%.
Example Product 8 had a non-fat milk solids content of 15.4%, a milk fat content of 1.8%, and a total solids content of 27.0%.

(Comparative Example 1)
Comparative Example 1 was obtained in the same manner as in Example 1, except that an aqueous solution of 9% skim milk powder, 0.15% agar with a jelly strength of 700 g/ ^cm2 , 8% sugar, 3.5% cream with a 50% milk fat content, and 0% milk protein enzymatic hydrolysate HW-3 (manufactured by Megmilk Snow Brand Co., Ltd.) was dissolved in water and the pH was adjusted to 6.6 without using a pH adjuster.

(Comparative Example 2)
Comparative Example 2 was obtained in the same manner as in Example 1, except that an aqueous solution of 9% skim milk powder, 0.15% agar with a jelly strength of 700 g/ ^cm2 , 8% sugar, 3.5% cream with a 50% milk fat content, and 1.7% milk protein enzymatic hydrolysate HW-3 (manufactured by Megmilk Snow Brand Co., Ltd.) was dissolved in water to a pH of 6.6 without adjusting the pH using a pH adjuster.

(Comparative Example 3)
Comparative Example 3 was obtained in the same manner as in Example 1, except that an aqueous solution was prepared by dissolving 9% skim milk powder, 0.15% agar with a jelly strength of 700 g/ ^cm2 , 8% sugar, 3.5% cream with a 50% milk fat content, and 1.7% milk protein enzymatic hydrolysate HW-3 (manufactured by Megmilk Snow Brand Co., Ltd.) in water, and the pH was adjusted to 7.5 using a pH adjuster.

(Comparative Example 4)
Comparative Example 4 was obtained in the same manner as in Example 1, except that 9% skim milk powder, 0% agar with a jelly strength of 700 g/ ^cm2 , 8% sugar, 3.5% cream with a 50% milk fat content, and 1.7% milk protein enzymatic hydrolysate HW-3 (manufactured by Megmilk Snow Brand Co., Ltd.) were dissolved in water.

(Evaluation of mix properties after sterilization process)
The properties of the mix after the sterilization step were visually inspected and evaluated as either "○: the mix after sterilization is uniform" or "×: the mix after sterilization is in an aggregated or separated state."

(Transportation test evaluation method)
The evaluation method for the transportation test was as follows: 20 samples filled in 100 ml containers were packed in plastic containers, loaded into a refrigerated truck at 5°C, and transported 1000 km. After transportation, samples whose structure was not broken down were evaluated as ◯, and samples whose structure was broken down or water separation occurred were evaluated as ×.

The evaluation results of Example Products 1 to 8 and Comparative Examples 1 to 4 are shown in Tables 1, 2, and 3. For Example Products 1 to 8, the hardness was within the range of 18 g f to 70 g f at the time points D+1 to D+18. The transportation test results were ◯.

Comparative Example 1, which does not contain a milk protein hydrolysate, had a hardness of 32 g f at D+1 and was evaluated as good in the transportation test. Comparative Example 2, which contains a milk protein hydrolysate and has a raw material mixture solution pH of 6.6 at sterilization, had a hardness of 6 g f at D+1 and was evaluated as bad in the transportation test. Comparative Example 3, which contains a milk protein hydrolysate and has a raw material mixture solution pH of 7.5 at sterilization, had uneven mix properties after sterilization. Comparative Example 4, which does not contain agar, had a hardness of 16 g f at D+1, resulting in insufficient hardness.

Therefore, by adjusting the pH of the raw material containing the milk protein hydrolysate to 6.7-7.4 and then sterilizing it, hardness is imparted to the fermented milk after fermentation, resulting in a static fermented milk that is highly resistant to transportation.

The present invention makes it possible to provide fermented milk containing a milk protein hydrolysate that has a hardness that can withstand vibrations during distribution.

Claims (3)

A method for producing agar-containing fermented milk, comprising a sterilization step of a raw material mixture solution containing a whey protein hydrolysate,
The pH of the raw material mixture solution in the sterilization step is 6.7 to 7.4;
The whey protein hydrolysate content is 1.0% by weight to 2.2% by weight based on the fermented milk, and the agar content is 0.05% by weight to 0.3% by weight based on the fermented milk,
The method for producing agar-containing fermented milk, wherein the fermented milk has a hardness of 18 gf to 70 gf at 10°C after refrigerated storage for one day after production. A fermented milk containing a whey protein hydrolysate and agar, wherein the whey protein hydrolysate content is 1.0 % by weight to 2.2 % by weight based on the fermented milk, and the agar content is 0.05 % by weight to 0.3% by weight based on the fermented milk, and the fermented milk has a hardness of 18 gf to 70 gf at 10°C after refrigerated storage for one day after production. A fermented milk containing a whey protein hydrolysate and agar, wherein the whey protein hydrolysate content is 1.0 % by weight to 2.2 % by weight based on the fermented milk, and the agar content is 0.05 % by weight to 0.3% by weight based on the fermented milk, and the fermented milk has a hardness of 18 gf to 70 gf at 10°C at any time up to 18 days after refrigerated storage after production.