Fermented milk

Abstract

To provide fermented milk which is high in protein but has low hardness and does not harden during storage, and a manufacturing method of the same.SOLUTION: The above-mentioned problems can be solved by making a protein content of fermented milk 8.0 wt.% or more based on the total weight, and making the weight ratio of the protein derived from a microparticulated whey protein material to the total protein 0.50 or more. The fermented milk of the present invention has a hardness of less than 50 gf. The microparticulated whey protein material used in the fermented milk of the present invention has (a) a weight ratio of the protein to the total solid of less than 0.60, (b) a 50% particle size (D50) of 0.5 to 10 μm, and (c) a modification degree of the whey protein of 60% or more.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to fermented milk. More specifically, the present invention relates to fermented milk containing a high concentration of protein and a method for producing the same. [Background technology]

[0002] Whey, a by-product of cheese and casein production from animal milk such as cow's milk, contains lactose, minerals, and whey protein. Whey protein is recognized as a high-quality protein source, and whey protein ingredients such as WPC (Whey Protein Concentrate) and WPI (Whey Protein Isolate) are manufactured and sold by concentrating whey using an UF membrane to increase the whey protein concentration and reduce the lactose and mineral concentrations. In recent years, microparticulated whey ingredients and manufacturing equipment have been marketed, utilizing the heat-induced denaturation and aggregation properties of whey protein. Microparticulated whey is generally whey protein aggregates with a volume-based median diameter (50% particle size) of 0.5–10 μm, and refers to the fraction that precipitates upon centrifugation at 5,000 g–15,000 g.

[0003] Since protein is an important nutrient, there is a demand for fermented milk products that are high in protein.

[0004] Patent Document 1 aims to provide a method for producing fermented milk containing a high concentration of protein with excellent flavor and texture, and as a means for achieving this, it discloses a method for producing fermented milk, characterized in that the protein content is 5 to 10 mass %, and when the total protein is taken as 100%, the skim milk powder contains 20 to 60 mass % of protein, the whey protein concentrate contains 20 to 30 mass % of protein, and the milk protein concentrate contains 20 to 60 mass % of protein.

[0005] Patent Document 2 aims to provide fermented milk that has appropriate hardness and viscosity, little syneresis, a stable texture, and an excellent flavor, and is inexpensive, as well as a method for producing the same; and further aims to provide fermented milk that has excellent quality as described above, in which fermentation is accelerated to shorten the fermentation time, and a method for producing the same.As a means for achieving these goals, it discloses fermented milk with a stable texture, which is obtained by blending 1 to 15% by weight of milk protein concentrate and delactose permeate in a raw material mix, and a method for producing the fermented milk.

[0006] Patent Document 3 aims to provide a solid yogurt that maintains its shape and water retention properties and has a pleasant texture even when deterioration occurs due to storage conditions such as temperature rise and physical stimulation during product delivery or storage, and a method for producing the same. The patent document 3 discloses a solid yogurt that contains substantially non-aggregating denatured protein spherical particles or aggregates thereof and gelatin, and a method for producing solid yogurt that comprises inoculating and culturing lactic acid bacteria into a milk raw material, the method comprising adding a step of adding substantially non-aggregating denatured protein spherical particles or aggregates thereof and gelatin before or after the culturing step.

[0007] Patent Document 4 discloses a high-protein, acidic dairy product that is a fermented milk product that has a good flavor despite its high protein content, and that contains a total amount of at least 7.0% by weight of protein, at least 2.0% by weight of a denatured whey protein composition solid, and a total amount of fat of at most 0.3% by weight, and has a pH of at most 5.5, wherein the denatured whey protein composition contains a total amount of at least 60% by weight of protein on a dry weight basis, a total amount of fat of at most 2.0% by weight on a dry weight basis, and insoluble whey protein particles having a particle size in the range of 1 to 20 microns, and the amount of the insoluble whey protein particles is in the range of 50 to 100% by weight of the total amount of protein in the acidic dairy product.

[0008] Patent Document 5 aims to provide a novel high-protein static fermented milk that is high in protein but has low hardness and few curd particles, and a method for producing the same, and discloses fermented milk that contains 3.4% to less than 7.0% by weight of protein, of which 10 to 80% by weight is MP whey. [Prior art documents] [Patent documents]

[0009] [Patent Document 1] International Publication No. 2017 / 029802 [Patent Document 2] Japanese Patent Application Publication No. 11-28056 [Patent Document 3] Japanese Patent Application Laid-Open No. 2002-238452 [Patent Document 4] Special Publication No. 2016-533726 [Patent Document 5] Japanese Patent Publication No. 2020-184925 Summary of the Invention [Problem to be solved by the invention]

[0010] In addition to the fermented milk and production methods thereof disclosed in Patent Documents 1 to 5, there is a need for fermented milk that is high in protein but has low hardness, does not harden during storage, and can be used as both static fermented milk and stirred fermented milk, and a production method thereof. Therefore, an object of the present invention is to provide a novel, unprecedented high-protein fermented milk and a method for producing the same. [Means for solving the problem]

[0011] The present invention provides an invention including the following configuration as a means for solving the above problems. [1] Fermented milk containing 8.0% or more by weight of protein based on the total weight, and having a weight ratio of protein derived from microparticulated whey protein material to total protein of 0.50 or more. [2] Fermented milk according to [1], having a hardness of less than 50 gf. [3] The fermented milk according to [1] or [2], wherein the microparticulated whey protein material has the following properties (a) to (c): (a) A weight ratio of protein to total solids of less than 0.60 (b) 50% particle size (D50) is 0.5 to 10 μm (c) The degree of denaturation of whey protein is 60% or more. [4] A method for producing fermented milk comprising the following steps (1) and (2): (1) preparing a fermentation mix containing 8.0% by weight or more of protein based on the total weight, and having a weight ratio of protein derived from a microparticulated whey protein material having the following properties (a) to (c) relative to the total protein of 0.50 or more: (a) A weight ratio of protein to total solids of less than 0.60 (b) 50% particle size (D50) is 0.5 to 10 μm (c) The degree of denaturation of whey protein is 60% or more. (2) A process in which a lactic acid bacteria starter is added to the fermentation mix and fermented. [Effects of the Invention]

[0012] According to the present invention, a new fermented milk product, which is high in protein but has low hardness and does not increase in hardness during storage, and which is not available in conventional products, and a method for producing the same are provided. [Brief explanation of the drawings]

[0013] [Figure 1] The hardness (gf) of fermented milk after storage at 10°C for 4, 7, 14 and 21 days after production is shown. DETAILED DESCRIPTION OF THE INVENTION

[0014] (fermented milk) In the present invention, "fermented milk" refers to milk obtained by fermenting animal milk such as cow's milk or milk containing an equivalent or higher content of nonfat milk solids with lactic acid bacteria, bifidobacteria, or yeast, or a combination thereof. Fermented milk can be classified according to its properties and production method into 1) settling type fermented milk, 2) stirred type fermented milk, and 3) liquid fermented milk. Settling type fermented milk (1) is called a hard type, and has a pudding-like texture that is filled into retail containers and fermented. It is produced, for example, as follows: First, a fermentation mix prepared by mixing and dissolving raw materials such as milk, dairy products, and sucrose is homogenized, sterilized, and cooled. After that, a lactic acid bacteria starter is inoculated, the mixture is filled into containers that are sealed, and fermented in a culture room or fermentation tunnel. When the appropriate acidity is reached, the mixture is immediately cooled to below 10°C to terminate the fermentation, and the final product is obtained. 2) Stirred fermented milk, also known as soft fermented milk, is made by adding a lactic acid bacteria starter to a fermentation mix, fermenting in a tank, crushing the curds, and filling into containers to produce the final product. 3) Liquid fermented milk is made by fermenting a fermentation mix in the same manner as stirred fermented milk, crushing the curds, and homogenizing the liquid fermented milk to produce the final product. Specific embodiments of the fermented milk of the present invention include 1) settling fermented milk and 2) stirred fermented milk.

[0015] Milk and dairy products that are the raw materials for fermented milk fall under the category of "milk" and "dairy products" in the Ministerial Ordinance on the Compositional Standards of Milk and Dairy Products (Ministry of Health and Welfare Ordinance No. 52 of December 27, 1951). In other words, "milk" refers to raw milk, cow's milk, special cow's milk, raw goat's milk, pasteurized goat's milk, raw sheep's milk, adjusted milk, low-fat milk, non-fat milk, and processed milk, while "dairy products" refers to cream, butter, butter oil, cheese, concentrated whey, ice cream, concentrated milk, concentrated skim milk, unsweetened evaporated milk, unsweetened evaporated skim milk, sweetened condensed milk, sweetened condensed skim milk, whole milk powder, skim milk powder, cream powder, whey powder, protein-enriched whey powder, buttermilk powder, sweetened milk powder, modified milk powder, fermented milk, lactic acid bacteria drinks (limited to those containing 3.0% or more non-fat milk solids), and dairy drinks.

[0016] (High-protein fermented milk) As used herein, "high-protein fermented milk" refers to fermented milk that can be described as high-protein and contains 8.1 g or more of protein per 100 kcal. There are no restrictions on the protein content of the fermented milk of the present invention, but it is preferably 8.0 wt. % or more, more preferably 9.0 wt. % or more, and even more preferably 10 wt. % or more, based on the total weight of the fermented milk. The fermented milk of the present invention is high in protein but has low hardness.

[0017] The fermented milk of the present invention contains a protein derived from a particulate whey protein material. The weight ratio of the protein derived from the particulate whey protein material to the total protein in the fermented milk of the present invention is preferably 0.50 or more, more preferably 0.60 or more, and even more preferably 0.70 or more. Furthermore, the content of the protein derived from the particulate whey protein material in the fermented milk of the present invention is preferably 4.0% by weight or more, more preferably 5.0% by weight or more, and even more preferably 6.0% by weight or more, based on the total weight of the fermented milk.

[0018] Next, preferred embodiments of the total protein content of the fermented milk of the present invention and the protein content derived from the microparticulated whey protein material will be further described. Note that the following contents are all based on the total amount of fermented milk. The fermented milk of the present invention preferably has (a) a protein content of 8.0% by weight or more and (b) a protein content derived from the microparticulated whey protein material of 4.0% by weight or more. The fermented milk of the present invention also preferably has (a2) a protein content of 9.0% by weight or more and (b2) a protein content derived from the microparticulated whey protein material of 5.0% by weight or more.

[0019] (Protein measurement method) The protein content of the fermented milk of the present invention can be measured by a common method for measuring the amount of protein, such as the BCA method, Bradford method, Lowry method, Biured method, Kjeldahl method, or combustion (modified Dumas) method.

[0020] (Hardness of fermented milk) Whey protein isolate (WPI) and / or whey protein concentrate (MPC) can be added to the fermented milk of the present invention in order to prevent a decrease in the hardness of the fermented milk. WPI and / or WPC can be blended in an amount of less than 1% by weight of protein relative to the fermented milk. To maximize the benefits of the present invention, it is preferable not to add components that adjust the hardness of the fermented milk, such as WPI or WPC. The hardness of the fermented milk of the present invention is preferably less than 50 gf, more preferably 40 gf, and even more preferably less than 30 gf, from the viewpoints of flavor, smoothness of texture, and ease of eating during storage.

[0021] (Hardness measurement method) The hardness of the fermented milk of the present invention can be measured using a texture analyzer (Eiko Seiki Co., Ltd.) and can be defined as the maximum load obtained in a two-time penetration test on the fermented milk. Specifically, the maximum load of the fermented milk can be measured by subjecting a sample adjusted to 10°C to the texture analyzer under the following conditions: test speed: 1 mm / s, penetration distance: 10 mm, jig: resin cylindrical probe with a diameter of 16 mm and a height of 25 mm, and mode: compression. The size of the sample should be such that it has a height of at least 10 mm of the penetration distance and a diameter of at least 16 mm.

[0022] (fat amount) The fat content of the fermented milk of the present invention is not particularly limited, but since the present invention relates to high-protein fermented milk, it is preferably 2% by weight or less in relation to the total solid content of the fermented milk. In other words, the fermented milk of the present invention is suitable for low-fat (2% by weight or less) and fat-free (substantially 0% by weight) fermented milk.

[0023] (microparticulated whey protein material) The microparticulated whey protein material used to produce the fermented milk of the present invention contains microparticulated whey, and further has (a) a weight ratio of protein to total solids (hereinafter also referred to as protein / total solids) of less than 0.60, (b) a 50% particle size (D50) of 0.5 to 10 μm, and (c) a degree of denaturation of whey protein of 60% or more. Here, in this specification, "microparticulated whey" refers to an aggregate of whey protein, which is a precipitate fraction obtained by subjecting a solution containing whey protein to heating and shearing treatment, followed by centrifugation.

[0024] The microparticulated whey protein material used in producing the fermented milk of the present invention can be obtained by heating and shearing a solution containing whey protein. The heating temperature may be any temperature at which the whey protein in the solution denatures and aggregates, and is preferably 70°C or higher, more preferably 80°C or higher, and even more preferably 90°C or higher. Shearing can be carried out using a commercially available high-pressure homogenizer or the like. A device capable of simultaneous heating and shearing is preferred, and for example, a scraping-type sterilizer or the like can be used, but the device is not limited to the above as long as it can heat and shear the whey solution. The microparticulated whey protein material used in producing the fermented milk of the present invention may be prepared by known methods, for example, the method described in International Journal of Food Science & Technology, 34(5-6), pp. 523-525. The microparticulated whey protein material used to produce the fermented milk of the present invention may be a commercially available microparticulated whey protein material, such as Simpless 100 (manufactured by C.P. Kelko) or WPC 550 (manufactured by Fonterra). The particulate whey protein material used in the fermented milk of the present invention may be used in its liquid form or may be further concentrated using an MF membrane or the like. It may also be used in the form of a powder obtained by spray drying or freeze drying. Furthermore, a precipitate fraction obtained by centrifuging a whey solution that has been heated and sheared, or an insoluble whey protein fraction obtained by removing soluble substances such as lactose and ash, may be used as the particulate whey protein material in the fermented milk.

[0025] The weight ratio of protein to total solids of the particulate whey protein material used to produce the fermented milk of the present invention is preferably less than 0.60, more preferably less than 0.55%, and even more preferably less than 0.50%. The total solid content of the particulate whey protein material can be determined by a heat drying method or near-infrared spectroscopy. The protein content of microparticulated whey protein materials can be measured using common protein content measurement methods such as the BCA method, Bradford method, Lowry method, Biured method, Kjeldahl method, and combustion (modified Dumas) method.

[0026] (Degree of whey protein denaturation) The degree of denaturation of the whey protein contained in the microparticulate whey protein material used in the fermented milk of the present invention is preferably 60% or more, more preferably 70% or more, even more preferably 80% or more, and even more preferably 90% or more.

[0027] (Method for measuring the degree of denaturation of whey protein) The degree of denaturation of the whey protein contained in the microparticulated whey protein material can be measured, for example, by the following method. 0.4 g of sample, 0.8 g of 40°C distilled water, and 40 μL of 10% acetic acid (volume) were dispensed into a microtube, stirred thoroughly, and then allowed to stand for 10 minutes. Then, 40 μL of 1M sodium acetate and 0.72 g of distilled water were dispensed into the microtube and stirred thoroughly again. After leaving the mixture for 1 hour, the mixture was centrifuged at 3000 g for 5 minutes. The protein content of the precipitate and the protein content of the supernatant obtained from this process were quantified. The amount of protein in the precipitate was taken as the amount of insoluble denatured whey protein, and the amount of protein in the supernatant was taken as the amount of soluble, undenatured whey protein. Furthermore, the same process was performed using distilled water instead of 10% acetic acid and 1M sodium acetate. The amount of protein in the supernatant was taken as the total whey protein content, and the degree of denaturation (%) of whey protein in the microparticulated whey protein material was calculated using the following formula. Protein quantification can be performed using the ThermoFisher BCA Protein Assay Kit. Denaturation rate (%) = Denatured whey protein amount / Total whey protein amount x 100 = (1 - undenatured whey protein / total whey protein) x 100

[0028] (50% particle size) The 50% particle size (D50) of the microparticulated whey protein material used to produce the fermented milk of the present invention is preferably 0.5 μm or more and 10 μm or less, more preferably 0.5 μm or more and 5 μm or less, even more preferably 1 μm or more and 5 μm or less, and even more preferably 1 μm or more and 3 μm or less. The 50% particle size (μm) of the microparticulated whey protein material used to produce the fermented milk of the present invention can be measured using a particle size distribution measurement device such as a laser diffraction particle size distribution analyzer, a laser diffraction / scattering particle size distribution analyzer, an image analysis particle size distribution analyzer, a precision particle size distribution analyzer, a real-time zeta potential / nanoparticle size analyzer, a dynamic light scattering (DLS) particle size distribution analyzer, an analytical ultracentrifuge system, etc. The particle size corresponding to 50% of the obtained cumulative distribution curve on a volume basis is taken as the 50% particle size (μm) of the microparticulated whey protein material used to produce the fermented milk of the present invention.

[0029] When producing the fermented milk of the present invention, the heating and shearing conditions of the whey solution may be adjusted, and the microparticulate whey protein material may be homogenized, as necessary, so that the degree of denaturation of the whey protein and the 50% particle size (μm) of the microparticulate whey protein material fall within the preferred ranges described above.

[0030] (Fermented milk manufacturing process) The fermented milk of the present invention can be obtained by a production method including the step of preparing a fermentation mix containing 8.0 wt. % or more of protein based on the total weight, and in which the weight ratio of protein derived from a particulate whey protein material having predetermined properties to the total protein is 0.50 or more. As a typical example of fermented milk, a method for producing a settling type fermented milk is shown below. Milk ingredients such as skim milk powder, MPC (Milk Protein Concentrate: MPC), WPC, WPI, microparticulated whey protein material, and other ingredients commonly used in the production of fermented milk are weighed and dissolved to obtain a mixed mix. The resulting mixed mix is ​​then homogenized, sterilized, and then cooled. There is no specific order for the homogenization and sterilization treatments. The homogenization conditions are a temperature of 50 to 70°C and a pressure of 50 to 500 kg / cm. 2 The sterilization conditions include, but are not limited to, a temperature of 80 to 95°C and a time of 2 seconds to 10 minutes. Lactic acid bacteria are added to the cooled raw material mix and filled into containers. When lactic acid bacteria are added, fermentation conditions include a fermentation temperature of 30-40°C, a fermentation time of 3-20 hours, and an end point when the lactic acid acidity of the mix reaches 0.7-1.3%. Examples of lactic acid bacteria used for fermentation include Lactobacillus bulgaricus (L. bulgaricus) and Streptococcus thermophilus (S. thermophilus), but there are no particular limitations as long as they are lactic acid bacteria starters commonly used in fermented milk production. After fermentation is complete, the container is cooled to 10°C or below to obtain static fermented milk.

[0031] The amount of particulate whey protein material added in the method for producing fermented milk of the present invention is preferably such that the weight ratio of protein derived from the particulate whey protein material to the total protein in the fermented milk is 0.50 or more, and the amount of particulate whey protein material added is such that the protein content derived therefrom is preferably 4.0 wt% or more, more preferably 5.0 wt% or more, and even more preferably 6.0 wt% or more, based on the total weight of the fermented milk. [Example]

[0032] Next, the present invention will be specifically explained by showing examples. However, the present invention should not be construed as being limited to the examples. Furthermore, unless otherwise specified, "%" represents % by weight based on the total weight of fermented milk.

[0033] (Preparation of microparticulated whey protein material) A UF concentrate of cheddar cheese whey was heated and sheared according to the method described in International Journal of Food Science & Technology, 34(5-6), pp. 523-525. The resulting suspension of microparticulated whey protein material was spray-dried to obtain a powder of microparticulated whey protein material (hereinafter also referred to as MPW in the tables). This powder had a whey protein to total solids weight ratio of 0.462, a degree of whey protein denaturation of 72%, a 50% particle size of 3.3 μm, and a lactose content of 45.8%. The resulting powder of microparticulated whey protein material was used to prepare the fermented milk products of the Examples and Comparative Examples described below.

[0034] (Protein measurement) The protein content in the powdered microparticulated whey protein material and the protein content in the skim milk powder were determined using SUMIGRAPH (registered trademark) NC-TRINITY (Sumika Chemical Analysis Center, Ltd.). The weight ratio of protein derived from the microparticulated whey protein material to the total protein in the fermented milk (hereinafter also referred to as MPW protein / total protein in the tables) was calculated by dividing the protein content derived from the microparticulated whey protein material by the total protein content.

[0035] (Measurement of Degree of Denaturation) The degree of denaturation of the whey protein contained in the microparticulated whey protein material was measured by the following method. 0.4 g of sample, 0.8 g of 40°C distilled water, and 40 μL of 10% acetic acid (volume) were dispensed into a microtube, vigorously stirred, and then allowed to stand for 10 minutes. Subsequently, 40 μL of 1M sodium acetate and 0.72 g of distilled water were dispensed into the microtube and vigorously stirred again. After standing for 1 hour, the mixture was centrifuged at 3000 g for 5 minutes. The protein content of the supernatant obtained from this process was quantified. The amount of protein in the precipitate was taken as the amount of insoluble denatured whey protein, and the amount of protein in the supernatant was taken as the amount of soluble, native whey protein. Furthermore, the same process was performed using distilled water instead of 10% acetic acid and 1M sodium acetate. The amount of protein in the supernatant was taken as the total whey protein content, and the degree of denaturation (%) of whey protein in the microparticulated whey protein material was calculated using the following formula. Protein quantification was performed using a ThermoFisher BCA Protein Assay Kit. Denaturation rate (%) = (1 - undenatured whey protein amount / total whey protein amount) x 100

[0036] (50% particle size) The 50% particle size of the microparticulated whey protein material was measured using a Microtrac (MT3300EXII, Nikkiso Co., Ltd.). A flow cell was used, and the refractive index of the sample was set to 1.65. The particle size corresponding to 50% of the obtained cumulative volume distribution curve was taken as the 50% particle size (μm) of the microparticulated whey protein material.

[0037] (Preparation of fermented milk) (Examples 1 to 2, Comparative Examples 1 to 3) According to the formulations shown in Table 1, static fermented milks of Examples 1 and 2 and Comparative Examples 1 to 3 were produced by the following preparation methods. Each raw material was mixed and dissolved with blending water at 65°C in a homomixer to prepare a mix. The mix was reheated to 65°C and heated to 140 kg / cm 2 The mixture was homogenized at a homogenizing pressure of 1000 kJ / min, and then heat-sterilized at 95°C for 30 seconds. It was then cooled to 40°C, and 1.5% by weight of Lactobacillus bulgaricus and 0.15% by weight of Streptococcus thermophilus were added, followed by filling into containers. The containers filled with the mix were fermented in a fermentation chamber set at 40°C, and when the acidity reached 1.00%, the mixture was cooled to 5°C to produce the static fermented milk products of Examples 1 and 2 and Comparative Examples 1 to 3. The resulting static fermented milk was stored at 10°C until subjected to the hardness test described below. All fermented milk products except for Comparative Example Product 1 contain 8.1 g or more of protein per 100 kcal, and can be labeled as high-protein fermented milk.

[0038] [Table 1]

[0039] (Hardness measurement) The hardness (gf) of the fermented milk products of the Examples and Comparative Examples stored at 10°C for 4, 7, 14, and 21 days after production was measured by a two-time penetration test using a texture analyzer. Samples adjusted to 10°C were placed in the texture analyzer under the following conditions: Test Speed: 1 mm / s, Penetration Distance: 10 mm, Jig: Resin Cylindrical Probe 16 mm in Diameter and 25 mm in Height, and Mode: Compression. The maximum load measured was taken as the hardness (gf) of the fermented milk. The measurement results of the hardness (gf) of the fermented milk are shown in Table 2 and FIG.

[0040] [Table 2]

[0041] The hardness of fermented milk containing 5.0% by weight of protein based on the total weight was less than 30 gf, and when stored at 10°C for 21 days after production, the hardness did not increase (Comparative Example 1). When the total protein content in the fermented milk was increased to 8.1% or 10.0% by weight based on the total weight, the hardness of the fermented milk became 60 gf or more and 100 gf or more, respectively, and after storage at 10°C for 21 days, the hardness increased to 80 gf and 130 gf, respectively (Examples 2 and 3). On the other hand, when the weight ratio of protein derived from the microparticulated whey protein material to the total protein of the fermented milk was 0.50 or more, even if the total protein content was 8.1 wt% or 10.0 wt% based on the total weight, the hardness of the fermented milk was less than 25 gf, and the hardness did not increase during storage at 10°C for 21 days after production (Examples 1 and 2). From the above, it was found that fermented milk containing 8% or more by weight of protein and having a weight ratio of protein derived from microparticulated whey protein material to the total protein of the fermented milk of 0.50 or more has the property of having a low hardness and not increasing in hardness even during storage.

Claims

1. Fermented milk containing 8.0% by weight or more of protein based on the total weight, and having a weight ratio of protein derived from a microparticulated whey protein material to total protein of 0.50 or more.

2. The fermented milk according to claim 1, having a hardness of less than 50 gf.

3. The fermented milk according to claim 1 or 2, wherein the microparticulated whey protein material has the following properties (a) to (c): (a) a protein to total solids weight ratio of less than 0.60; (b) 50% particle size (D50) is 0.5 to 10 μm (c) The degree of denaturation of whey protein is 60% or more.

4. A method for producing fermented milk comprising the following steps (1) and (2): (1) preparing a fermentation mix containing 8.0% by weight or more of protein based on the total weight, and having a weight ratio of protein derived from a microparticulated whey protein material having the following properties (a) to (c) relative to the total protein of 0.50 or more: (a) a protein to total solids weight ratio of less than 0.60; (b) 50% particle size (D50) is 0.5 to 10 μm (c) The degree of denaturation of whey protein is 60% or more. (2) A step of adding a lactic acid bacteria starter to the fermentation mix and fermenting it.

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