Method for producing high-protein milk raw material

Abstract

Provided is a method for producing a milk raw material (high-protein milk raw material) having a high protein content, in particular a method for producing a high-protein milk raw material having an improved flavor. The production method comprises the steps of: (1) preparing a milk fluid from a milk raw material, the milk fluid having a total solid content of 5-15 mass% and a milk-derived protein content of 50 parts by mass or more per 100 parts by mass of the total solid content; and (2) adding lactic acid bacteria to the milk fluid and maintaining the milk fluid containing the lactic acid bacteria until a pH in the range of 5.2 to 6.5 is reached, obtaining a lactic acid bacteria treated milk fluid having a pH in the range.

Description

[0001] Cross - reference to related patent applications

[0002] This application claims priority based on Japanese Patent Application No. 2022 - 146502 filed on September 14, 2022, the entire disclosure of which is incorporated herein by reference. Technical field

[0003] The present invention relates to a method for producing a milk raw material having a high protein content (referred to as "high - protein milk raw material" in the present invention). The present invention also relates to a high - protein milk raw material having an improved flavor. The present invention further relates to food and drink containing the high - protein milk raw material and a method for producing the same. The present invention further relates to a method for improving the flavor of the high - protein milk raw material. Background art

[0004] For example, a high - protein milk raw material containing 50% by mass or more of milk - derived proteins such as milk protein concentrate (MPC) and whey protein concentrate (WPC) (hereinafter referred to as "milk - derived proteins") has protein odors peculiar to milk - derived proteins. For this reason, food and drink containing a predetermined amount of such a raw material may have an impaired flavor.

[0005] To improve this situation, a method of adding amino acids and / or sweeteners such as glycine and / or aspartame to a protein - containing beverage to mask the casein odor derived from milk protein has been proposed (Patent Document 1). However, both glycine and aspartame are sweet substances; therefore, they may affect or impair the flavor of the protein - containing beverage depending on the amount of these substances added.

[0006] Other methods have also been proposed, such as a method of bringing a high - protein milk fluid having a protein content of 60% by mass or more in the total solid component content into contact with activated carbon, or a method of concentrating the fluid using a nanofiltration membrane (Patent Documents 2 and 3). These methods are useful for obtaining a high - protein milk raw material having a reduced milk - derived protein odor and an improved refreshing taste, but require equipment such as activated carbon columns and filters, and membrane module units.

[0007] A method using fermentation technology is known as a method for masking odors.

[0008] For example, Patent Document 4 discloses a method for masking the aloe-derived odor of fermented milk containing aloe, in which a fermented milk base is prepared by fermenting a fermented milk raw material containing bacteria of the genus Bifidobacterium and a lactic acid bacteria starter until the pH reaches 4.4 to 4.8, and the fermented milk base is mixed with a predetermined amount of aloe leaf pulp dispersion to reduce the grassy odor peculiar to aloe leaf pulp.

[0009] Patent Document 5 discloses a method for reducing the grassy odor, bitterness, and astringency peculiar to soybeans in a lactic acid-fermented soy milk food, in which soy milk is fermented using one or more lactic acid bacteria strains selected from Lactobacillus paracasei N-5 strain (deposit number: NITE P-02630), Lactococcus lactis hordniae Lhana strain (deposit number: NITE P-02631), and Lactobacillus pentosus Lpome-3 strain (deposit number: NITE P-02632) as the lactic acid bacteria starter used in the production of the lactic acid-fermented soy milk food. Patent Document 5 describes that this process reduces the unpleasant odor (grassy odor) and unpleasant taste (bitterness and astringency) peculiar to soybeans.

[0010] Prior art documents

[0011] Patent documents

[0012] Patent Document 1: JP2020-141559A

[0013] Patent Document 2: WO2020 / 085517A

[0014] Patent Document 3: WO2020 / 085518A

[0015] Patent Document 4: JP2017-176030A

[0016] Patent Document 5: JP2019-165667A Summary of the invention

[0017] Problems to be solved by the invention

[0018] The first object of the present invention is to provide a method for manufacturing a milk raw material containing a large amount of protein (high-protein milk raw material). Preferably, the object is to provide a method for manufacturing a high-protein milk raw material having a reduced protein odor (hereinafter referred to as "milk-source protein odor") caused by milk-source protein.

[0019] The second object of the present invention is to provide a high-protein milk raw material treated with lactic acid bacteria (hereinafter referred to as "high-protein milk raw material treated with lactic acid bacteria"). Preferably, it is intended to provide a high-protein milk raw material treated with lactic acid bacteria having a reduced milk-derived protein odor.

[0020] The third object of the present invention is to provide a novel food or drink containing a high-protein milk raw material treated with lactic acid bacteria and a method for producing the same.

[0021] The fourth object of the present invention is to provide a method for improving the flavor of a high-protein milk raw material by reducing the milk-derived protein odor in the high-protein milk raw material.

[0022] Means for Solving the Problems

[0023] The present inventors conducted extensive research to achieve the above objects and found that by preparing a milk fluid from a milk raw material having a total solid content of 5 to 15% by mass and a milk-derived protein content of 50 parts by mass or more per 100 parts by mass of the total solid content, and then using lactic acid bacteria to maintain the milk fluid until the milk fluid reaches a pH in the range of 5.2 to 6.5 (excluding the pH range in which curd is formed) (lactic acid bacteria treatment), a high-protein milk raw material having a reduced protein odor (milk-derived protein odor) caused by milk-derived proteins and an improved flavor can be obtained as compared with a high-protein milk raw material prepared without lactic acid bacteria treatment.

[0024] The present invention has been completed based on this finding and through further research, and includes the following embodiments.

[0025] (I) Method for manufacturing high-protein milk raw material

[0026] (I-1) A method for producing a high-protein milk raw material, comprising the following steps:

[0027] (1) Preparing a milk fluid from a milk raw material, the milk fluid having a total solid content of 5 to 15% by mass and a milk-derived protein content of 50 parts by mass or more per 100 parts by mass of the total solid content, and

[0028] (2) Adding lactic acid bacteria to the milk fluid and maintaining the milk fluid containing lactic acid bacteria until it reaches a pH in the range of 5.2 to 6.5 (lactic acid bacteria treatment), thereby obtaining a lactic acid bacteria-treated milk fluid having a pH in this range.

[0029] (I-2) The method for producing a high-protein milk raw material according to (I-1), further comprising the step of (3-1) concentrating the lactic acid bacteria-treated milk fluid or concentrating and drying the lactic acid bacteria-treated milk fluid.

[0030] (I-3) The method for manufacturing a high-protein milk raw material according to (I-1) further includes the step of drying the milk fluid treated with lactic acid bacteria.

[0031] (I-4) The method for manufacturing a high-protein milk raw material according to any one of (I-1) to (I-3), wherein the milk fluid contains whey protein as the milk source protein but does not contain casein.

[0032] (I-5) The method for manufacturing a high-protein milk raw material according to any one of (I-1) to (I-3), wherein

[0033] the milk fluid contains casein or casein and whey protein as the milk source protein,

[0034] Step (2) includes holding the milk fluid containing lactic acid bacteria until reaching a pH within the range of 6.0 to 6.5 (lactic acid bacteria treatment), and obtaining a milk fluid treated with lactic acid bacteria having a pH within this range.

[0035] (I-6) The manufacturing method according to (I-4), wherein the high-protein milk raw material is at least one member selected from the group consisting of whey protein concentrate (WPC) and whey protein isolate (WPI). WPC and WPI have been treated with lactic acid bacteria.

[0036] (I-7) The manufacturing method according to (I-5), wherein the high-protein milk raw material is at least one member selected from the group consisting of milk protein concentrate (MPC), milk protein isolate (MPI), and micellar casein concentrate (MCC). MPC, MPI, and MCC have been treated with lactic acid bacteria.

[0037] (I-8) The method for manufacturing a high-protein milk raw material according to any one of (I-1) to (I-7) does not include the step of treating the milk fluid obtained in step (1) or the milk fluid treated with lactic acid bacteria obtained in step (2) with activated carbon.

[0038] The manufacturing method of the present invention improves the flavor of the high-protein milk raw material by treating the milk fluid obtained in step (1) with lactic acid bacteria. Therefore, the method of the present invention is different from the techniques that attempt to improve the flavor by removing impurities through the use of activated carbon treatment or the like.

[0039] (II) High-protein milk raw material treated with lactic acid bacteria

[0040] (II-1) A liquid lactic acid bacteria-treated high-protein milk raw material, which includes a milk source protein in an amount of 50 parts by mass or more in every 100 parts by mass of the total solid content,

[0041] The lactic acid bacteria-treated high-protein milk raw material includes at least dead cells of lactic acid bacteria, diacetyl, and 3-hydroxy-2-butanone, and

[0042] The high-protein milk raw material treated with lactic acid bacteria has a pH in the range of 5.2 to 6.5.

[0043] (II-2) The high-protein milk raw material treated with lactic acid bacteria according to (II-1), wherein the high-protein milk raw material treated with lactic acid bacteria contains whey protein as the milk source protein but does not contain casein.

[0044] (II-3) The high-protein milk raw material treated with lactic acid bacteria according to (II-1),

[0045] wherein

[0046] the high-protein milk raw material treated with lactic acid bacteria contains casein or casein and whey protein as the milk source protein, and

[0047] the high-protein milk raw material treated with lactic acid bacteria has a pH in the range of 6.0 to 6.5.

[0048] (II-4) A semi-solid or solid high-protein milk raw material treated with lactic acid bacteria, which is obtained by concentrating and / or drying the liquid high-protein milk raw material treated with lactic acid bacteria according to any one of (II-1) to (II-3).

[0049] (III) Food and beverage and method for manufacturing the same

[0050] (III-1) A method for manufacturing a food or drink, which includes the step of adding the high-protein milk raw material obtained by the manufacturing method according to any one of (I-1) to (I-8) to the food or drink.

[0051] (III-2) A food or drink, which includes the high-protein milk raw material treated with lactic acid bacteria according to any one of (II-1) to (II-4).

[0052] (IV) Method for improving flavor of high-protein milk raw material

[0053] (IV-1) A method for improving the flavor of a high-protein milk raw material, which includes the following steps:

[0054] (1) Preparing a milk fluid from the milk raw material, the milk fluid having a total solid content of 5 to 15% by mass and a content of milk source protein of 50 parts by mass or more per 100 parts by mass of the total solid content, and

[0055] (2) Adding lactic acid bacteria to the milk fluid and maintaining the milk fluid containing lactic acid bacteria until a pH in the range of 5.2 to 6.5 is reached (lactic acid bacteria treatment), thereby obtaining a lactic acid bacteria-treated milk fluid having a pH in this range.

[0056] Effects of the Invention

[0057] Compared with the high-protein milk raw material not treated with lactic acid bacteria, the high-protein milk raw material produced by the manufacturing method according to the present invention has a significantly reduced milk-derived protein odor. Therefore, the present invention can provide a high-protein milk raw material with a reduced milk-derived protein odor and an improved flavor. In addition, although the content of milk-derived protein in the total solid component content per 100 parts by mass is as high as 50 parts by mass or more, the high-protein milk raw material of the present invention has a reduced milk-derived protein odor, and thus can be added to food and beverages without impairing the flavor. In addition, compared with the high-protein milk raw material not treated with lactic acid bacteria, the flavor improvement method according to the present invention can significantly reduce the milk-derived protein odor in the high-protein milk raw material. Detailed Description

[0058] (I) Method for manufacturing high-protein milk raw material

[0059] The manufacturing method of the present invention at least includes the following steps:

[0060] (1) Preparing a milk fluid from a milk raw material, the milk fluid having a total solid component content of 5 to 15% by mass and a content of milk-derived protein in the total solid component content per 100 parts by mass of 50 parts by mass or more (hereinafter this step is referred to as the "milk fluid preparation step"), and

[0061] (2) Adding lactic acid bacteria to the milk fluid and maintaining the milk fluid containing lactic acid bacteria until a pH in the range of 5.2 to 6.5 is reached (lactic acid bacteria treatment), thereby obtaining a lactic acid bacteria-treated milk fluid having a pH in this range (this step is also referred to as the "lactic acid bacteria treatment step").

[0062] The manufacturing method of the present invention can be described as a method for manufacturing a high-protein milk raw material having a significantly reduced milk-derived protein odor compared with a high-protein milk raw material not treated with lactic acid bacteria. Preferably, the manufacturing method of the present invention can be described as a method for manufacturing a high-protein milk raw material having a significantly reduced milk-derived protein odor and a refreshing aftertaste (improved refreshing feeling) compared with a high-protein milk raw material not treated with lactic acid bacteria. In particular, the manufacturing method of the present invention, wherein the pH used in the lactic acid bacteria treatment step is 6.0 to 6.5, can be described as a method for manufacturing a high-protein milk raw material having a significantly reduced milk-derived protein odor and a refreshing aftertaste (improved refreshing feeling) but no sour taste (no acidic flavor) compared with a high-protein milk raw material not treated with lactic acid bacteria.

[0063] (1) Step for preparing milk liquid

[0064] The "milk raw material" used as the starting material in the milk fluid preparation step is a raw material for preparing a milk fluid having a total solid content of 5 to 15% by mass and a milk source protein content of 50 parts by mass or more per 100 parts by mass of the total solid content; as long as this requirement is met, it is sufficient if the milk raw material contains at least milk source protein as a milk component. As long as the effects of the present invention are not adversely affected, the milk raw material may also contain other milk components such as milk fat, lactose, and / or ash. The milk raw material can be in any form, but can be, for example, a fluid such as a liquid or semi-solid (such as gel-like), or can be a solid containing milk components (such as powder-like, particulate, granular, or flake-like (tablet-like)).

[0065] Examples of the milk raw material include raw milk squeezed from dairy cows, cow's milk (whole milk), skim milk, whole milk powder, skim milk powder, whole milk concentrate, concentrated skim milk, whey, whey powder, desalted whey, desalted whey powder, whey protein concentrate (WPC), whey protein isolate (WPI), milk protein concentrate (MPC), milk protein isolate (MPI), and micellar casein concentrate (MCC).

[0066] There is no particular limitation on the milk raw material, and it is preferably a milk raw material having a high content of milk source protein relative to the total solid content. Specific examples include whey protein concentrate (WPC), whey protein isolate (WPI), milk protein concentrate (MPC), milk protein isolate (MPI), and micellar casein concentrate (MCC).

[0067] The total solid content of the milk fluid prepared in the milk fluid preparation step is 5 to 15% by mass, and the milk source protein content is 50 parts by mass or more per 100 parts by mass of the total solid content. The milk fluid includes liquid and semi-solid fluids containing a high concentration of milk source protein.

[0068] The total solid content of the milk fluid, as described above, can be in the range of 5 to 15% by mass, preferably 6 to 14% by mass, more preferably 7 to 13% by mass, and even more preferably 8 to 12% by mass. As used herein, the "total solid content" refers to the percentage of the total amount of solid components contained in 100% by mass of the milk fluid. The total solid content includes milk components contained in the milk fluid (such as milk source protein, milk fat, carbohydrates, and ash).

[0069] As described above, the milk source protein content per 100 parts by mass of the total solid content in the milk fluid can be 50 parts by mass or more, preferably 60 parts by mass or more, more preferably 70 parts by mass or more, even more preferably 75 parts by mass or more, and particularly preferably 80 parts by mass or more. There is no limitation on the upper limit value, but it can be, for example, 95 parts by mass.

[0070] "The content of milk-derived protein in 100 parts by mass of the total solid content" means the percentage (parts by mass) of milk-derived protein when the total amount of solid components contained in the milk fluid is regarded as 100 parts by mass. The total amount of solid components contained in the milk fluid can be measured according to ISO6731 (IDF 21 Milk - Determination of total solid content). The protein content in the milk fluid can be calculated by multiplying the nitrogen content measured by the combustion method or the Kjeldahl method by the nitrogen-to-protein conversion coefficient.

[0071] There is no particular limitation on the milk fluid. Preferred examples include the retentate obtained by treating whey and / or acid whey with an ultrafiltration (UF) membrane, the permeate or retentate obtained by treating the retentate obtained by treating whey and / or acid whey with an ultrafiltration (UF) membrane with a microfiltration (MF) membrane, the retentate obtained by treating whole milk and / or skim milk with an ultrafiltration (UF) membrane, the permeate or retentate obtained by treating the retentate obtained by treating whole milk and / or skim milk with an ultrafiltration (UF) membrane with a microfiltration (MF) membrane, the permeate or retentate obtained by treating whole milk and / or skim milk with a microfiltration (MF) membrane, whey protein concentrate (WPC: protein accounting for about 80% by mass of the total solid content), whey protein isolate (WPI: protein accounting for about 90% by mass of the total solid content), milk protein concentrate (MPC: protein accounting for about 80% by mass of the total solid content), milk protein isolate (MPI: protein accounting for about 90% by mass of the total solid content), and micellar casein concentrate (protein accounting for about 80% by mass of the total solid content).

[0072] In the above, the term "retentate" refers to the liquid ("concentrate") that does not permeate the membrane in membrane treatment and remains on the membrane and is concentrated. The term "permeate" refers to the liquid that has permeated the membrane in membrane treatment. For example, when the retentate obtained by subjecting whey and / or acid whey to UF treatment is subjected to MF membrane treatment, components other than whey protein are allowed to remain on the MF membrane, thereby providing a permeate with an increased whey protein concentration. When the retentate obtained by concentrating protein from whole milk and / or skim milk by UF membrane treatment is subjected to MF membrane treatment, a retentate with selectively enriched micellar casein and a permeate containing whey protein are produced.

[0073] There is no particular limitation on the method for preparing a milk fluid from milk raw materials, as long as it is a method for preparing a milk fluid having a total solid content of 5 to 15% by mass and a milk source protein content of 50 parts by mass or more per 100 parts by mass of the total solid content by using one type of milk raw material or a combination of two or more types of milk raw materials. Examples of such methods include a method of using the milk raw material as it is or using a combination of two or more types of milk raw materials, a method of dissolving (reconstituting) the milk raw material in water or hot water (warm water, hot water), a method of subjecting the milk raw material or its reconstituted product to defatting treatment and then to membrane treatment, and a method of subjecting the milk raw material or its reconstituted product to acid treatment or enzyme treatment and then to membrane treatment.

[0074] The milk fluid thus prepared is preferably subjected to a sterilization treatment before being subjected to the lactic acid bacterium treatment step described below. The sterilization treatment can be carried out as long as it does not interfere with the lactic acid bacterium treatment described below, and is preferably carried out until the general bacterial count in the milk fluid is reduced to 1000 cfu / ml or less. The sterilization treatment can be carried out under any conditions and by any method that can achieve this purpose, and there is no particular limitation. Examples of the sterilization treatment include heat treatment methods for sterilizing cow's milk, such as the ultra-high temperature instantaneous sterilization (UHT sterilization) method of carrying out heat treatment at 120 to 150°C for 2 to 3 seconds, the high temperature short time sterilization (HTST sterilization) method of continuously carrying out heat treatment at 72°C or higher, for example, 72 to 75°C for 15 seconds or more, the high temperature holding sterilization (HTLT sterilization) method of carrying out heat treatment in a holding mode at 75°C or higher for 15 minutes or more, the low temperature holding sterilization (LTLT sterilization) method of carrying out heat treatment in a holding mode at 63 to 65°C for 30 minutes, the continuous low temperature sterilization (LTLT sterilization) method of carrying out heat treatment in a continuous mode at 65 to 68°C for 30 minutes or more, and the ultra-high temperature sterilization (LL sterilization) method of carrying out heat treatment at 135 to 150°C for 1 to 4 seconds. In addition, the sterilization treatment is not limited to the above methods, and it is sufficient if the heat history represented by the heating temperature (product temperature) × heating time × pressure is equal to or greater than the above sterilization methods. For example, as will be described in the experimental examples below, a method of heating the milk fluid until the product temperature reaches 95°C (reach temperature: 95°C) under normal pressure conditions can be used. As used herein, "normal pressure" means that the pressure inside the container is in a normal pressure state and does not include a pressure state in which the pressure is artificially increased or decreased.

[0075] (2) Step for treating with lactic acid bacteria

[0076] There is no particular limitation on the lactic acid bacteria used in the lactic acid bacteria treatment step, and they can be those lactic acid bacteria commonly used in the production of fermented milk, such as Lactobacillus bulgaricus (L. bulgaricus), Streptococcus thermophilus (S. thermophilus), Lactobacillus casei (L. casei), Lactobacillus lactis (L. lactis), Lactobacillus gasseri (L. gasseri), Lactobacillus plantarum (L. plantarum), Lactobacillus acidophilus (L. acidophilus), and Bifidobacteria. The lactic acid bacteria used can be a single type or a combination of two or more types.

[0077] In an embodiment where a single type of lactic acid bacteria is used, the lactic acid bacteria used are preferably Lactobacillus bulgaricus, Streptococcus thermophilus, or Lactobacillus casei. More preferably, the lactic acid bacteria used are Lactobacillus bulgaricus 1589 (NITE BP - 03716), Lactobacillus bulgaricus OLL 1073R - 1 (FERM P - 17227), Streptococcus thermophilus 3078 (NITE BP - 01697), or Lactobacillus casei P2203401. In an embodiment where two or more types of lactic acid bacteria are used in combination, the lactic acid bacteria used are preferably a combination of Lactobacillus bulgaricus and Streptococcus thermophilus, more preferably a combination of Lactobacillus bulgaricus 1589 and Streptococcus thermophilus 3078 or a combination of Lactobacillus bulgaricus OLL 1073R - 1 and Streptococcus thermophilus 3078, and even more preferably a combination of Lactobacillus bulgaricus 1589 and Streptococcus thermophilus 3078. In addition, as a combination of Lactobacillus bulgaricus and Streptococcus thermophilus, lactic acid bacteria isolated from fermented dairy products (e.g., Meiji Bulgarian - style yogurt, Meiji Bereliyo yogurt LG 21, Meiji Bereliyo yogurt R - 1, Meiji Bulgarian - style yogurt dessert type, etc.) can also be used.

[0078] There is no particular limitation on the amount of lactic acid bacteria added to the milk fluid, and it can be, for example, 10 6 to 10 8 cfu / ml, preferably 5×10 6 to 10 8 cfu / ml, and more preferably 10 7 to 10 8 cfu / ml.

[0079] The lactic acid bacteria treatment can be carried out on the milk fluid by adding lactic acid bacteria to the milk fluid and then keeping the milk fluid static or stirred at a predetermined temperature.

[0080] There is no particular limitation on the temperature for the lactic acid bacteria treatment, as long as it is a temperature at which the milk fluid (initial pH of about 7.0) can be adjusted to a final pH in the range of 5.2 to 6.5 without forming curd. The lower limit of the temperature for the lactic acid bacteria treatment is, for example, 30 °C, preferably 32 °C, more preferably 34 °C, and even more preferably 36 °C. The upper limit of the temperature for the lactic acid bacteria treatment is, for example, 45 °C, preferably 44 °C, and more preferably 43 °C. The temperature range for the lactic acid bacteria treatment can be set by combining these lower and upper limits as needed. Examples of selectable temperature ranges include, but are not limited to, 30 to 45 °C, 32 to 44 °C, 34 to 43 °C, and 36 to 43 °C.

[0081] An example of the method for keeping the milk fluid static is to keep the milk fluid static in a jacketed tank or a constant temperature room. The method for stirring and keeping the milk fluid can be any method under any conditions where the milk fluid can be uniformly stirred and mixed at least. An example is the method of stirring and mixing the milk fluid with stirring blades, where the milk fluid is kept in a jacketed tank or a constant temperature room.

[0082] There is no particular limitation on the time for the lactic acid bacteria treatment, as long as it is a time that allows the milk fluid (initial pH of about 7.0) to be adjusted to a final pH in the range of 5.2 to 6.5 without forming curd. In other words, the lactic acid bacteria treatment can end at a time point when the pH falls within the range of 5.2 to 6.5 without causing the lactic acid bacteria-treated milk fluid to form curd. The lower limit of the time for the lactic acid bacteria treatment is, but not limited to, for example, 0.5 hour, preferably 1 hour, more preferably 1.5 hours, and even more preferably 2 hours. The upper limit of the time for the lactic acid bacteria treatment is, for example, 12 hours, preferably 10 hours, more preferably 9 hours, and even more preferably 8 hours. The time range for the lactic acid bacteria treatment can be set by combining these lower and upper limits as needed. Although not limited thereto, examples of selectable time ranges include 0.5 to 12 hours, 1 to 10 hours, 1.5 to 9 hours, and 2 to 8 hours.

[0083] The lactic acid bacteria treatment can be ended by heating the lactic acid bacteria-treated milk fluid to kill all or part of the lactic acid bacteria contained in the milk fluid or reduce the activity of all or part of the lactic acid bacteria. There is no particular limitation on the method and conditions for this heat treatment, as long as they can achieve the above object and do not interfere with the effects of the present invention. For example, a method of heating the milk fluid until its temperature reaches 60 °C (temperature reached: 60 °C) can be used.

[0084] The pH at the end of the lactic acid bacteria treatment can be set as follows according to the components of the milk fluid actually used.

[0085] (a) In the case of a milk fluid that does not contain casein but contains whey protein as the milk source protein:

[0086] The pH at the end of the lactic acid bacteria treatment is 5.2 to 6.5, preferably 5.6 to 6.5, more preferably 5.8 to 6.5, even more preferably 6.0 to 6.5, and particularly preferably 6.0 to 6.4.

[0087] When the pH at the end of the lactic acid bacteria treatment is 5.8 or higher, preferably 6.0 or higher, the resulting lactic acid bacteria-treated milk fluid does not taste sour and has a good flavor.

[0088] Here, the milk fluid includes, for example, WPC and WPI.

[0089] (b) In the case of a milk fluid that contains casein or contains casein and whey protein as the milk source protein:

[0090] The pH at the end of the lactic acid bacteria treatment is 6.0 to 6.5, preferably 6.0 to 6.4 or 6.1 to 6.5, and more preferably 6.1 to 6.4.

[0091] If the pH at the end of the lactic acid bacteria treatment is 6.0 or higher, the resulting lactic acid bacteria-treated milk fluid does not taste sour and has a good flavor.

[0092] Here, the milk fluid includes, for example, MPC, MPI, and MCC.

[0093] Adjusting the pH range at the end of the lactic acid bacteria treatment according to the components of the milk fluid as described above reduces the milk source protein odor, which is one of the effects of the present invention, and thus provides a high-protein milk raw material with a good flavor.

[0094] Another characteristic of those high-protein milk raw materials with a pH of 6.0 or higher among these high-protein milk raw materials is that they have less sour taste (acidity). Therefore, in order to obtain a high-protein milk raw material with a reduced milk source protein odor and a reduced sour taste, it is preferable to set the pH at the end of the lactic acid bacteria treatment to 6.0 or higher.

[0095] The method and equipment for treating the milk fluid with lactic acid bacteria can be known methods and equipment used in the fermentation treatment of raw milk. For example, the lactic acid bacteria treatment can be carried out by using known methods and equipment used in the manufacture of fermented dairy products such as yogurt.

[0096] The lactic acid bacteria-treated milk fluid thus prepared can optionally be subjected to a concentration step and / or a drying step to convert the milk fluid into a semi-solid or solid form.

[0097] There are no particular limitations on the concentration step, and it includes, for example, subjecting the milk fluid treated with lactic acid bacteria to a vacuum evaporation concentration treatment (evaporation) or a dehydration (+ desalting) treatment such as a reverse osmosis (RO) membrane treatment or a nanofiltration (NF) membrane treatment, to obtain a semi-solid milk fluid treated with lactic acid bacteria having a total solid content of 20 to 50% by mass. The milk fluid treated with lactic acid bacteria obtained in the concentration step can be in a liquid state or a gel state. The total solid content in 100% by mass of the milk fluid treated with lactic acid bacteria is, for example, 20 to 50% by mass, preferably 20 to 40% by mass, more preferably 20 to 35% by mass, and even more preferably 20 to 30% by mass.

[0098] There are no particular limitations on the drying step, and examples include subjecting the milk fluid treated with lactic acid bacteria or the semi-solid milk fluid treated with lactic acid bacteria after the concentration step to a dehydration treatment such as a spray drying treatment, a freeze drying treatment, or a drum drying treatment, to obtain a dried product (solid state) of the milk fluid treated with lactic acid bacteria having a moisture content of 2 to 5% by mass. The dried product of the milk fluid treated with lactic acid bacteria obtained in the drying step can be in a powder form or a particulate form, or can be in a granular form obtained by adjusting or granulating the powder or particulate, or can be in a flake form (tablet form) obtained by tableting (compression molding) the powder or particulate.

[0099] (II) High-protein milk raw material treated with lactic acid bacteria

[0100] The high-protein milk raw material treated with lactic acid bacteria of the present invention is a liquid high-protein milk raw material having a milk-derived protein content of 50 parts by mass or more in the total solid content per 100 parts by mass, and contains at least dead cells of lactic acid bacteria, diacetyl, and 3-hydroxy-2-butanone, and has a pH in the range of 5.2 to 6.5. Preferably, the high-protein milk raw material treated with lactic acid bacteria of the present invention is a raw material prepared (manufactured) according to the above manufacturing method.

[0101] As described above, the milk-derived protein content in the total solid content per 100 parts by mass of the high-protein milk raw material treated with lactic acid bacteria can be 50 parts by mass or more, and is preferably 60 parts by mass or more, more preferably 70 parts by mass or more, even more preferably 75 parts by mass or more, and particularly preferably 80 parts by mass or more. The upper limit is, but not limited to, for example, 95 parts by mass.

[0102] The pH of the high-protein milk raw material treated with lactic acid bacteria can be set as follows according to the components of the high-protein milk raw material treated with lactic acid bacteria.

[0103] (a) In the case of a high-protein milk raw material treated with lactic acid bacteria that does not contain casein but contains whey protein as the milk-derived protein:

[0104] The pH is from 5.2 to 6.5, preferably from 5.6 to 6.5, more preferably from 5.8 to 6.5, even more preferably from 6.0 to 6.5, and particularly preferably from 6.0 to 6.4.

[0105] When the pH is 5.8 or higher, preferably 6.0 or higher, the lactic acid bacteria-treated milk fluid has no sour taste and has a good flavor.

[0106] Here, the lactic acid bacteria-treated high-protein milk raw material includes, for example, WPC and WPI.

[0107] (b) In the case of a lactic acid bacteria-treated high-protein milk raw material containing casein or containing casein and whey protein as milk source proteins:

[0108] The pH is from 6.0 to 6.5, preferably from 6.0 to 6.4, or from 6.1 to 6.5, more preferably from 6.1 to 6.4.

[0109] When the pH is 6.0 or higher, the lactic acid bacteria-treated milk fluid has no sour taste and has a good flavor.

[0110] Here, the lactic acid bacteria-treated high-protein milk raw material includes, for example, MPC, MPI, and MCC.

[0111] In other words, as described above, those lactic acid bacteria-treated high-protein milk raw materials having a pH of 6.0 or higher among these lactic acid bacteria-treated high-protein milk raw materials have a reduced milk source protein odor and a reduced sour taste.

[0112] Diacetyl and 3-hydroxy-2-butanone (hereinafter referred to as "acetoin") are aroma components (index substances of fermentation aroma) produced, for example, when milk components are fermented with lactic acid bacteria. As shown in the experimental examples described below, it has been confirmed that the milk fluid treated with lactic acid bacteria has an increased amount of these aroma components. It is considered that due to the increase in these aroma components, the lactic acid bacteria-treated high-protein milk raw material of the present invention has a reduced milk source protein odor and a good flavor compared to the high-protein milk raw material not treated with lactic acid bacteria.

[0113] There is no particular limitation on the proportion of diacetyl contained in the high-protein milk raw material treated with lactic acid bacteria, and it can be 0.00001 to 0.001% by mass (0.1 to 10 ppm), preferably 0.00002 to 0.001% by mass (0.2 to 10 ppm) in the total solid content per 100% by mass of the high-protein milk raw material treated with lactic acid bacteria. There is no particular limitation on the proportion of acetoin contained in the high-protein milk raw material treated with lactic acid bacteria, and it can be 0.00001 to 0.01% by mass (0.1 to 100 ppm), preferably 0.00002 to 0.01% by mass (0.2 to 100 ppm) in the total solid content per 100% by mass of the high-protein milk raw material treated with lactic acid bacteria.

[0114] The aroma components can be analyzed based on the methods and operations described in the experimental examples below.

[0115] There is no particular limitation on the proportion of diacetyl contained in the liquid high-protein milk raw material treated with lactic acid bacteria, and compared with the proportion of diacetyl contained in the high-protein milk raw material produced according to the same formula and manufacturing method as the liquid high-protein milk raw material treated with lactic acid bacteria except without lactic acid bacteria treatment (defined as "1"), it is, for example, 1 or more, preferably more than 1, more preferably 1.5 or more, even more preferably 1.5 to 10, even more preferably 1.5 to 9, and even more preferably 1.5 to 8. There is no particular limitation on the proportion of diacetyl contained in the solid high-protein milk raw material treated with lactic acid bacteria, and compared with the proportion of diacetyl contained in the high-protein milk raw material produced according to the same formula and manufacturing method as the solid high-protein milk raw material treated with lactic acid bacteria except without lactic acid bacteria treatment (defined as "1"), it is, for example, 1 or more, preferably more than 1, more preferably 1.5 or more, even more preferably 1.5 to 10, even more preferably 1.5 to 9, and even more preferably 1.5 to 8.

[0116] The "proportion of diacetyl contained in the high-protein milk raw material" can be determined from the chart (peak) area value corresponding to diacetyl in the headspace solid-phase microextraction of gas chromatography-mass spectrometry as described in the experimental examples below (the same applies to acetoin, dimethyl disulfide, dimethyltrisulfide, nonanal, and δ-decalactone in the following text).

[0117] There is no particular limitation on the proportion of acetoin contained in the liquid lactic acid bacterium-treated high-protein milk raw material, and compared with the proportion of acetoin contained in a high-protein milk raw material that is not treated with lactic acid bacteria and is produced according to the same formulation and production method as the liquid lactic acid bacterium-treated high-protein milk raw material (defined as "1"), it is, for example, 1 or more, preferably more than 1, more preferably 1.5 or more, even more preferably 1.5 to 1000, even more preferably 1.5 to 900, and even more preferably 1.5 to 850. There is no particular limitation on the proportion of acetoin contained in the solid lactic acid bacterium-treated high-protein milk raw material, and compared with the proportion of acetoin contained in a high-protein milk raw material that is not treated with lactic acid bacteria and is produced according to the same formulation and production method as the solid lactic acid bacterium-treated high-protein milk raw material (defined as "1"), it is, for example, 1 or more, preferably more than 1, more preferably 1.5 or more, even more preferably 1.5 to 1000, even more preferably 1.5 to 900, and even more preferably 1.5 to 850.

[0118] Dimethyldisulfide (DMDS) and dimethyltrisulfide (DMTS) are, for example, aroma components (indicator substances for protein deterioration) generated when heating milk components containing proteins, and nonanal is, for example, an aroma component (indicator substance for lipid deterioration) generated when heating milk components containing lipids. As shown in the experimental examples described below, these aroma components are reduced by treating milk fluid with lactic acid bacteria. Due to the reduction of these aroma components, or the reduction of these components in combination with the increase in diacetyl and acetoin, the lactic acid bacterium-treated high-protein milk raw material of the present invention has a reduced milk source protein odor compared with the high-protein milk raw material not treated with lactic acid bacteria. In addition, as the unpleasant flavor is also reduced, the lactic acid bacterium-treated high-protein milk raw material has a good flavor and a refreshing aftertaste.

[0119] There is no particular limitation on the proportion of DMDS contained in the lactic acid bacterium-treated high-protein milk raw material, and it may be 0.00000001 to 0.0000005% by mass (0.1 to 5 ppb), preferably 0.00000001 to 0.0000004% by mass (0.1 to 4 ppb) in the total solid content of every 100% by mass of the lactic acid bacterium-treated high-protein milk raw material. There is no particular limitation on the proportion of DMTS contained in the lactic acid bacterium-treated high-protein milk raw material, and it may be 0.000000004 to 0.0000005% by mass (0.04 to 5 ppb), preferably 0.000000004 to 0.0000004% by mass (0.04 to 4 ppb) in the total solid content of every 100% by mass of the lactic acid bacterium-treated high-protein milk raw material. In addition, there is no particular limitation on the proportion of nonanal contained in the lactic acid bacterium-treated high-protein milk raw material, and it may be 0.00000001 to 0.000001% by mass (0.1 to 10 ppb), preferably 0.00000001 to 0.0000009% by mass (0.1 to 9 ppb) in the total solid content of every 100% by mass of the lactic acid bacterium-treated high-protein milk raw material.

[0120] The aroma components can be analyzed according to the methods and operations described in the experimental examples below.

[0121] There is no particular limitation on the proportion of DMDS contained in the liquid lactic acid bacterium-treated high-protein milk raw material, and compared with the proportion of DMDS (defined as "1") contained in the high-protein milk raw material manufactured according to the same formulation and manufacturing method as the liquid lactic acid bacterium-treated high-protein milk raw material except without lactic acid bacterium treatment, it is, for example, 1 or less, preferably less than 1, more preferably 0.9 or less, even more preferably 0.2 to 0.9, even more preferably 0.3 to 0.9, and even more preferably 0.3 to 0.8. There is no particular limitation on the proportion of DMDS contained in the solid lactic acid bacterium-treated high-protein milk raw material, and compared with the proportion of DMDS (defined as "1") contained in the high-protein milk raw material manufactured according to the same formulation and manufacturing method as the solid lactic acid bacterium-treated high-protein milk raw material except without lactic acid bacterium treatment, it is, for example, 1 or less, preferably less than 1, more preferably 0.9 or less, even more preferably 0.2 to 0.9, even more preferably 0.3 to 0.9, and even more preferably 0.3 to 0.8.

[0122] There is no particular limitation on the proportion of DMTS contained in the liquid lactic acid bacteria-treated high-protein milk raw material, and compared with the proportion of DMTS contained in a high-protein milk raw material (defined as "1") that is manufactured according to the same formula and manufacturing method as the liquid lactic acid bacteria-treated high-protein milk raw material except without lactic acid bacteria treatment, it is, for example, 1 or less, preferably less than 1, more preferably 0.9 or less, even more preferably 0.2 to 0.9, even more preferably 0.3 to 0.9, and even more preferably 0.3 to 0.8. There is no particular limitation on the proportion of DMTS contained in the solid lactic acid bacteria-treated high-protein milk raw material, and compared with the proportion of DMTS contained in a high-protein milk raw material (defined as "1") that is manufactured according to the same formula and manufacturing method as the solid lactic acid bacteria-treated high-protein milk raw material except without lactic acid bacteria treatment, it is, for example, 1 or less, preferably less than 1, more preferably 0.9 or less, even more preferably 0.2 to 0.9, even more preferably 0.3 to 0.9, and even more preferably 0.3 to 0.8.

[0123] There is no particular limitation on the proportion of nonanal contained in the liquid lactic acid bacteria-treated high-protein milk raw material, and compared with the proportion of nonanal contained in a high-protein milk raw material (defined as "1") that is manufactured according to the same formula and manufacturing method as the liquid lactic acid bacteria-treated high-protein milk raw material except without lactic acid bacteria treatment, it is, for example, 1 or less, preferably less than 1, more preferably 0.9 or less, even more preferably 0.1 to 0.9, even more preferably 0.2 to 0.9, and even more preferably 0.3 to 0.9. There is no particular limitation on the proportion of nonanal contained in the solid lactic acid bacteria-treated high-protein milk raw material, and compared with the proportion of nonanal contained in a high-protein milk raw material (defined as "1") that is manufactured according to the same formula and manufacturing method as the solid lactic acid bacteria-treated high-protein milk raw material except without lactic acid bacteria treatment, it is, for example, 1 or less, preferably less than 1, more preferably 0.9 or less, even more preferably 0.1 to 0.9, even more preferably 0.2 to 0.9, and even more preferably 0.3 to 0.9.

[0124] δ-Decalactone is an index substance of milk flavor. As will be shown in the experimental examples below, even when milk fluid is treated with lactic acid bacteria, δ-decalactone is hardly changed. In other words, the δ-decalactone content in the high-protein milk raw material treated with lactic acid bacteria is equivalent to that in the high-protein milk raw material not treated with lactic acid bacteria. This indicates that the high-protein milk raw material treated with lactic acid bacteria has the same milk flavor as the high-protein milk raw material not treated with lactic acid bacteria. In other words, the milk flavor is not significantly impaired by the treatment with lactic acid bacteria. There is no particular limitation on the proportion of δ-decalactone contained in the high-protein milk raw material treated with lactic acid bacteria, but it may be 0.00000001 to 0.0000005% (0.1 to 5 ppb), preferably 0.00000002 to 0.0000005% (0.2 to 5 ppb) in the total solid content per 100 mass% of the high-protein milk raw material treated with lactic acid bacteria.

[0125] The aroma components can be analyzed based on the methods and operations described in the experimental examples below.

[0126] There is no particular limitation on the proportion of δ-decalactone contained in the liquid high-protein milk raw material treated with lactic acid bacteria, and compared with the proportion of δ-decalactone (defined as "1") contained in the high-protein milk raw material manufactured according to the same formula and manufacturing method as the liquid high-protein milk raw material treated with lactic acid bacteria except that it is not treated with lactic acid bacteria, it is, for example, 0.7 to 1.3, preferably 0.7 to 1.2, more preferably 0.8 to 1.2, even more preferably 0.8 to 1.1, even more preferably 0.9 to 1.1, and even more preferably 0.9 to 1. There is no particular limitation on the proportion of δ-decalactone contained in the solid high-protein milk raw material treated with lactic acid bacteria, and compared with the proportion of δ-decalactone (defined as "1") contained in the high-protein milk raw material manufactured according to the same formula and manufacturing method as the solid high-protein milk raw material treated with lactic acid bacteria except that it is not treated with lactic acid bacteria, it is, for example, 0.7 to 1.3, preferably 0.7 to 1.2, more preferably 0.8 to 1.2, even more preferably 0.8 to 1.1, even more preferably 0.9 to 1.1, and even more preferably 0.9 to 1.

[0127] The high-protein milk raw material treated with lactic acid bacteria of the present invention includes, but is not particularly limited to, those having the following concentrations of free amino acids in the total solid content per kilogram of the high-protein milk raw material treated with lactic acid bacteria.

[0128] (a) In the case of a high-protein milk raw material treated with lactic acid bacteria that does not contain casein but contains whey protein as the milk source protein (specifically, WPC or WPI):

[0129] - Histidine (His): for example, 30 μmol / kg or more, preferably 30 to 1000 μmol / kg, more preferably 40 to 900 μmol / kg, and even more preferably 50 to 800 μmol / kg.

[0130] - Asparagine (Asn): for example, 10 μmol / kg or more, preferably 10 to 300 μmol / kg, more preferably 10 to 250 μmol / kg, and even more preferably 15 to 200 μmol / kg.

[0131] - Serine (Ser): for example, 30 μmol / kg or more, preferably 30 to 2500 μmol / kg, more preferably 40 to 2000 μmol / kg, and even more preferably 50 to 1500 μmol / kg.

[0132] - Glutamine (Gln): for example, 10 μmol / kg or more, preferably 10 to 300 μmol / kg, more preferably 10 to 250 μmol / kg, and even more preferably 15 to 200 μmol / kg.

[0133] - Glycine (Gly): for example, 100 μmol / kg or more, preferably 100 to 2500 μmol / kg, more preferably 100 to 2000 μmol / kg, and even more preferably 100 to 1500 μmol / kg.

[0134] - Aspartic acid (Asp): for example, 30 μmol / kg or more, preferably 30 to 1000 μmol / kg, more preferably 40 to 900 μmol / kg, and even more preferably 50 to 800 μmol / kg.

[0135] - Threonine (Thr): for example, 20 μmol / kg or more, preferably 20 to 1000 μmol / kg, more preferably 30 to 900 μmol / kg, and even more preferably 30 to 800 μmol / kg.

[0136] - Alanine (Ala): for example, 80 μmol / kg or more, preferably 80 to 2000 μmol / kg, more preferably 100 to 1500 μmol / kg, and even more preferably 100 to 1000 μmol / kg.

[0137] - Proline (Pro): for example, 100 μmol / kg or more, preferably 100 to 2500 μmol / kg, more preferably 200 to 2500 μmol / kg, and even more preferably 200 to 2000 μmol / kg.

[0138] - Lysine (Lys): for example, 200 μmol / kg or more, preferably 200 to 2500 μmol / kg, more preferably 300 to 2000 μmol / kg, and even more preferably 300 to 1500 μmol / kg.

[0139] - Methionine (Met): for example, 10 μmol / kg or more, preferably 10 to 1000 μmol / kg, more preferably 10 to 800 μmol / kg, and even more preferably 15 to 600 μmol / kg.

[0140] - Isoleucine (Ile): for example, 10 μmol / kg or more, preferably 10 to 1000 μmol / kg, more preferably 10 to 800 μmol / kg, and even more preferably 15 to 600 μmol / kg.

[0141] - Valine (Val): for example, 30 μmol / kg or more, preferably 30 to 3000 μmol / kg, more preferably 40 to 2500 μmol / kg, and even more preferably 50 to 2000 μmol / kg.

[0142] - Leucine (Leu): for example, 30 μmol / kg or more, preferably 30 to 1500 μmol / kg, more preferably 50 to 1200 μmol / kg, and even more preferably 80 to 1000 μmol / kg.

[0143] (b) In the case of a high-protein milk raw material treated with lactic acid bacteria containing casein or containing casein and whey protein as milk source proteins (specifically, MPC, MPI, and MCC):

[0144] - Histidine (His): for example, 30 μmol / kg or more, preferably 30 to 1000 μmol / kg, more preferably 40 to 900 μmol / kg, and even more preferably 50 to 800 μmol / kg.

[0145] - Asparagine (Asn): for example, 10 μmol / kg or more, preferably 10 to 300 μmol / kg, more preferably 10 to 250 μmol / kg, and even more preferably 15 to 200 μmol / kg.

[0146] - Glutamine (Gln): for example, 10 μmol / kg or more, preferably 10 to 2000 μmol / kg, more preferably 30 to 1500 μmol / kg, and even more preferably 50 to 1000 μmol / kg.

[0147] - Glycine (Gly): for example, 100 μmol / kg or more, preferably 100 to 2000 μmol / kg, more preferably 150 to 1500 μmol / kg, and even more preferably 150 to 1000 μmol / kg.

[0148] - Arginine (Arg): for example, 50 μmol / kg or more, preferably 50 to 2000 μmol / kg, more preferably 60 to 1700 μmol / kg, and even more preferably 80 to 1500 μmol / kg.

[0149] - Aspartic acid (Asp): for example, 40 μmol / kg or more, preferably 40 to 1000 μmol / kg, more preferably 50 to 900 μmol / kg, and even more preferably 60 to 800 μmol / kg.

[0150] - Threonine (Thr): for example, 20 μmol / kg or more, preferably 20 to 600 μmol / kg, more preferably 30 to 500 μmol / kg, and even more preferably 30 to 400 μmol / kg.

[0151] - Alanine (Ala): for example, 50 μmol / kg or more, preferably 50 to 2000 μmol / kg, more preferably 70 to 1700 μmol / kg, and even more preferably 100 to 1500 μmol / kg.

[0152] - Proline (Pro): for example, 60 μmol / kg or more, preferably 60 to 2500 μmol / kg, more preferably 100 to 2000 μmol / kg, and even more preferably 150 to 2000 μmol / kg.

[0153] - Lysine (Lys): for example, 50 μmol / kg or more, preferably 50 to 2000 μmol / kg, more preferably 70 to 1700 μmol / kg, and even more preferably 100 to 1500 μmol / kg.

[0154] - Tyrosine (Tyr): for example, 20 μmol / kg or more, preferably 20 to 2000 μmol / kg, more preferably 25 to 1500 μmol / kg, and even more preferably 30 to 1000 μmol / kg.

[0155] - Methionine (Met): for example, 5 μmol / kg or more, preferably 5 to 600 μmol / kg, more preferably 10 to 500 μmol / kg, and even more preferably 15 to 400 μmol / kg.

[0156] -Isoleucine (Ile): for example, 20 μmol / kg or more, preferably 20 to 1000 μmol / kg, more preferably 25 to 800 μmol / kg, and even more preferably 30 to 600 μmol / kg.

[0157] -Valine (Val): for example, 20 μmol / kg or more, preferably 20 to 2500 μmol / kg, more preferably 50 to 2000 μmol / kg, and even more preferably 80 to 1500 μmol / kg.

[0158] -Leucine (Leu): for example, 20 μmol / kg or more, preferably 20 to 1500 μmol / kg, more preferably 50 to 1200 μmol / kg, and even more preferably 80 to 1000 μmol / kg.

[0159] -Phenylalanine (Phe): for example, 20 μmol / kg or more, preferably 20 to 1000 μmol / kg, more preferably 25 to 800 μmol / kg, and even more preferably 30 to 600 μmol / kg.

[0160] These free amino acids can be analyzed according to the methods and operations described in the experimental examples below.

[0161] The high-protein milk raw material treated with lactic acid bacteria covered by the present invention includes a high-protein milk raw material treated with lactic acid bacteria prepared in a semi-solid or solid form by subjecting a liquid high-protein milk raw material treated with lactic acid bacteria to a concentration treatment and / or a drying treatment.

[0162] There is no particular limitation on the concentration treatment, and it includes, for example, a method of subjecting a milk fluid treated with lactic acid bacteria to a vacuum evaporation concentration treatment (evaporation) or a dehydration (+ desalting) treatment, such as a reverse osmosis (RO) membrane treatment or a nanofiltration (NF) membrane treatment, to obtain a semi-solid milk fluid treated with lactic acid bacteria having a total solid content of 20 to 50% by mass. The milk fluid treated with lactic acid bacteria obtained in the concentration step may be in a liquid or semi-solid (gel-like) state. The total solid content is preferably 20 to 40% by mass, more preferably 20 to 35% by mass, and even more preferably 20 to 30% by mass.

[0163] There is no particular limitation on the drying treatment, and examples include a method of subjecting a milk fluid treated with lactic acid bacteria or a semi-solid milk fluid treated with lactic acid bacteria obtained in a concentration step to a dehydration treatment such as spray drying treatment, freeze drying treatment, or drum drying treatment, to obtain a dried product of a solid milk fluid treated with lactic acid bacteria having a moisture content of 2 to 5% by mass. The dried product of the milk fluid treated with lactic acid bacteria obtained in the drying step may be in the form of powder or fine particles, or may be in the form of granules obtained by adjusting or granulating the powder or fine particles, or may be in the form of tablets (lozenge-like) obtained by tableting (compression molding) the powder or fine particles.

[0164] (III) Food and beverage and method for manufacturing the same

[0165] In an embodiment of the present invention, there is provided a method for manufacturing a food or drink, which includes a step of adding a high-protein milk raw material treated with lactic acid bacteria manufactured by the manufacturing method of the present invention to the food or drink.

[0166] In addition to the high-protein milk raw material treated with lactic acid bacteria manufactured by the manufacturing method of the present invention, any components may be optionally blended (mixed) into the food or drink. There is no particular limitation on such optional components, but they include components that are usually blended into food or drink, such as aqueous raw materials, oil-based raw materials, sugars, dietary fibers, polysaccharides, proteins, peptides, amino acids, lipids, organic acids, various physiologically active substances, vitamins, minerals, acidulants, flavors, sweeteners, emulsifiers, thickeners, gelling agents, functional materials, oils and fats, excipients, colorants, preservatives, and water (hot water, warm water, normal temperature water, and cold water).

[0167] In a preferred embodiment of the present invention, there is provided a method for manufacturing a food or drink, which includes mixing one or more members selected from the group consisting of aqueous raw materials, oil-based raw materials, flavors, sweeteners, emulsifiers, thickeners, gelling agents, functional materials, oils and fats, excipients, and water with a high-protein milk raw material treated with lactic acid bacteria manufactured by the manufacturing method of the present invention, and adding the mixture to the food or drink.

[0168] Examples of the aqueous raw materials that can be contained in the food or drink of the present invention include milk raw materials (cow's milk, skim milk, low-fat milk, milk with adjusted composition, etc.), milk beverages, fermented milk, soy milk, fruit juices, vegetable juices, fruit / vegetable purees, fruit / vegetable extracts, alcoholic beverages, and liquid sugars, etc., other than the high-protein milk raw material treated with lactic acid bacteria of the present invention. Examples of the oil-based raw materials that can be contained in the food or drink of the present invention include butter, margarine, shortening, cream, chocolate, cocoa mass, cocoa butter, and almond paste.

[0169] The food or drink product produced by the production method according to the present invention may be in any form, such as a solution, suspension, emulsion, powder, paste, semi-solid formed product or solid formed product, as long as it is in a form that can be ingested orally. There are no particular limitations, and examples include instant foods such as instant noodles, steamed foods, canned foods, microwave foods, instant soups (including miso soup) and freeze-dried foods; beverages such as soft drinks, fruit juice drinks, vegetable drinks, soy milk drinks, coffee drinks, tea drinks, powder drinks, concentrated drinks and alcoholic beverages; wheat flour products such as bread, pasta, noodles, cake powder and bread flour; confectioneries such as maltose, toffee, gummy candies, chewing gum, chocolate, cookies, crackers, bars, cakes, pies, snacks, saltine crackers, Japanese confectioneries, puddings, jellies, mousses, desserts and cold desserts; seasonings such as sauces, tomato processed seasonings, flavor seasonings, cooking dressings, sauce dressings, dipping sauces, and curry / stew sauce; oils and fats such as processed oils, butter, margarine and mayonnaise; dairy products such as milk drinks, fermented milk, lactic acid bacteria drinks, ice cream products (ice cream, ice milk, milk ice cream) and creams; agricultural processed products such as canned agricultural products, jams / marmalades and grains; frozen foods; and liquid foods. The food or drink product also includes health foods, functional foods (including, for example, foods for specified health use, foods with a nutrition function claim or foods with a functional claim), nutritional supplements, foods for special dietary uses (including, for example, foods for patients, infant formula, milk powder for pregnant and lactating women, or foods for persons with dysphagia) and infant liquid formula (also known as infant liquid milk). Among them, beverages, confectioneries, dairy products and liquid foods are preferred, and fermented milk, milk drinks, coffee drinks, tea drinks, soft drinks, powder drinks, liquid foods, ice cream products (ice cream, ice milk, milk ice cream), cold desserts and puddings are more preferred.

[0170] The production method of the food or drink product of the present invention may be any production method as long as it includes the step of adding the high-protein milk raw material treated with the lactic acid bacteria of the present invention. For example, the food or drink product may be produced according to a conventional method according to the product.

[0171] Because the high-protein milk raw material treated with the lactic acid bacteria incorporated into the food or drink product of the present invention has a reduced milk-derived protein odor, the high-protein milk raw material treated with the lactic acid bacteria does not impair the original flavor of the food or drink product, and can enhance the protein content of the food or drink product while maintaining a pleasant flavor. Therefore, the present invention can provide a production method of a food or drink product that has a reduced milk-derived protein odor despite containing milk-derived protein.

[0172] As used herein, the phrase "reduced milk-derived protein odor" means a reduction in the protein odor derived from a high-protein milk raw material. Specifically, this means that, compared with using a high-protein milk raw material not treated with lactic acid bacteria, using the high-protein milk raw material treated with the lactic acid bacteria of the present invention as the high-protein milk raw material results in a reduced milk-derived protein odor. As used herein, the phrase "protein odor" refers to the protein odor (retronasally) felt in the area from the oral cavity to the nasal cavity. More objectively, the reduction in milk-derived protein odor can also be evaluated based on the fact that, compared with using a high-protein milk raw material not treated with lactic acid bacteria, using the high-protein milk raw material treated with the lactic acid bacteria of the present invention as the high-protein milk raw material results in a decrease in DMDS and / or DMTS (which are index substances for protein deterioration). More objectively, the reduction in milk-derived protein odor can also be evaluated by using the following as an index: compared with using a high-protein milk raw material not treated with lactic acid bacteria, using the high-protein milk raw material treated with the lactic acid bacteria of the present invention as the high-protein milk raw material results in a decrease in DMDS and / or DMTS and an increase in diacetyl and / or acetoin (which are index substances for fermented flavor).

[0173] Therefore, the food or drink obtained by the production method according to the present invention has a reduced protein odor derived from the high-protein milk raw material used as the milk raw material. In other words, in an embodiment, compared with using a high-protein milk raw material not treated with lactic acid bacteria, the present invention provides a food or drink having a reduced protein odor derived from the high-protein milk raw material by using the high-protein milk raw material treated with lactic acid bacteria as the high-protein milk raw material. In a further preferred embodiment, compared with using a high-protein milk raw material not treated with lactic acid bacteria, the present invention provides a food or drink having a reduced unpleasant flavor and an improved refreshing feeling by using the high-protein milk raw material treated with lactic acid bacteria as the high-protein milk raw material. Such a flavor improvement effect is considered to be achieved, for example, by a reduction in the protein odor derived from the high-protein milk raw material used as the milk raw material.

[0174] (IV) Method for improving flavor of high-protein milk raw material

[0175] The present invention relates to a method for improving the flavor of a high-protein milk raw material, which comprises the following steps:

[0176] (1) preparing a milk fluid from a milk raw material having a total solid content of 5 to 15% by mass and a milk-derived protein content of 50 parts by mass or more per 100 parts by mass of the total solid content; and

[0177] (2) adding lactic acid bacteria to the milk fluid and maintaining the milk fluid containing the lactic acid bacteria until a pH in the range of 5.2 to 6.5 is reached, thereby obtaining a lactic acid bacteria-treated milk fluid having a pH in this range.

[0178] These steps (1) and (2) are as explained in (I) above, and the description in (I) is incorporated herein by reference. Further, as described in (I), the lactic acid bacteria-treated milk fluid may be subjected to a sterilization treatment after step (1), and similarly, the lactic acid bacteria-treated milk fluid may be subjected to a concentration treatment and / or a drying treatment after step (2).

[0179] The phrase "flavor improvement" at least includes the meaning of "reduction of milk source protein odor". The phrase "reduction of milk source protein odor" means a reduction in the protein odor derived from the high-protein milk raw material. Specifically, this means that, compared with using a high-protein milk raw material not treated with lactic acid bacteria, using the lactic acid bacteria-treated high-protein milk raw material obtained by performing the above steps (1) and (2) as the high-protein milk raw material results in a reduced protein odor. The phrase "protein odor" as used herein refers to the protein odor felt in the area from the oral cavity to the nasal cavity (retronasally). More objectively, the reduction of the milk source protein odor can also be evaluated based on the fact that, compared with using a high-protein milk raw material not treated with lactic acid bacteria, using the lactic acid bacteria-treated high-protein milk raw material of the present invention as the high-protein milk raw material results in a decrease in DMDS and / or DMTS (which are index substances for the deterioration of proteins). More objectively, the reduction of the milk source protein odor can also be evaluated based on the following: compared with using a high-protein milk raw material not treated with lactic acid bacteria, using the lactic acid bacteria-treated high-protein milk raw material of the present invention as the high-protein milk raw material results in a decrease in DMDS and / or DMTS and an increase in diacetyl and / or acetoin (which are index substances for the fermented aroma).

[0180] The phrase "flavor improvement" preferably further includes the meaning of "refreshing aftertaste". The phrase "refreshing aftertaste" also means a reduction in the unpleasant taste derived from the high-protein milk raw material. Specifically, this means that, compared with using a high-protein milk raw material not treated with lactic acid bacteria, using the lactic acid bacteria-treated high-protein milk raw material obtained by performing the above steps (1) and (2) as the high-protein milk raw material leaves a refreshing aftertaste. More objectively, the refreshing aftertaste can also be evaluated based on the following: compared with using a high-protein milk raw material not treated with lactic acid bacteria, using the lactic acid bacteria-treated high-protein milk raw material of the present invention as the high-protein milk raw material results in a decrease in DMDS and / or DMTS and an increase in diacetyl and / or acetoin.

[0181] In this specification, the terms "comprise / include" and "contain" include the meanings of "consist of" and "consist essentially of".

[0182] Examples

[0183] The present invention will be described with reference to experimental examples to facilitate understanding of the configuration and effects of the present invention. However, the present invention is not limited by these experimental examples in any way. Unless otherwise specified, the following experiments were conducted at room temperature (25 ± 5 °C) and atmospheric pressure (normal pressure). Unless otherwise specified, the following unit “%” means mass %, and the following unit “parts” means parts by mass.

[0184] The raw materials and lactic acid bacteria used in the experimental examples (Examples and Comparative Examples) described below are as follows.

[0185] Raw materials

[0186] · Milk protein concentrate (MPC): MPC4850 (casein: 64%, whey: 16%), powdery, Fonterra

[0187] · Whey protein concentrate (WPC): WPC392 (whey: 80%), powdery, Fonterra

[0188] Lactic acid bacteria

[0189] (a) Lactobacillus delbrueckii subsp. bulgaricus 1589 (NITE BP-03716) (hereinafter referred to as “bulgaricus 1589”).

[0190] Bulgaricus 1589 was internationally deposited on August 9, 2022, at the Patent Microorganisms Depositary, National Institute of Technology and Evaluation, 2-5-8122 Kamigou, Kisarazu-shi, Chiba-ken, Japan, under the classification name “Lactobacillus delbrueckii subsp. bulgaricus 1589” (deposit number: NITE BP-03716).

[0191] (b) Lactobacillus delbrueckii subsp. bulgaricus OLL 1073R-1 (FERM BP-10741) (hereinafter referred to as “bulgaricus OLL1073R-1”) (high EPS (exopolysaccharide)-producing strain)

[0192] Bulgaricus OLL 1073R-1 was internationally deposited on February 22, 1999 (domestic deposit date) at the International Patent Organism Depositary, National Institute of Advanced Industrial Science and Technology, 1-1-1 Higashi 1-chome, Tsukuba-shi, Ibaraki-ken, Japan, under the classification name “Lactobacillus delbrueckii subsp. bulgaricus OLL 1073R-1” (deposit number: FERM BP-10741).

[0193] In April 2012, the Patent Biological Depositary Center of the National Institute of Advanced Industrial Science and Technology merged with the Patent Microbial Depositary Center of the National Institute of Technology and Evaluation (NITE), and the microbial depositary business is currently conducted by the Patent Microbial Depositary Center of the National Institute of Technology and Evaluation (NITE-IPOD) (Room 120, 2-5-8 Kamigeneral Kamenosuke, Kisarazu City, Chiba Prefecture 292-0818, Japan).

[0194] (c) Streptococcus thermophilus (3078) (NITE BP-01697) (hereinafter referred to as "thermophilus 3078")

[0195] Thermophilus 3078 was internationally deposited at the said Patent Microbial Depositary Center on August 23, 2013, under the taxonomic name "Streptococcus thermophilus OLS3078" (deposit number: NITE BP-01697).

[0196] (d) Lactobacillus casei P2203401 (hereinafter referred to as "casei P2203401")

[0197] In the experimental examples described below, the aroma components and free amino acids were analyzed according to the following methods.

[0198] Analysis of aroma components

[0199] (a) Analysis method

[0200] Headspace solid-phase microextraction (HS-SPME) method of gas chromatography-mass spectrometry (GC / MS)

[0201] (b) Preparation of analysis sample

[0202] Liquid sample: The liquid sample (3 mL) and saturated brine (5 mL) were placed in a vial (20 mL) and mixed.

[0203] Powdery sample: The powdery sample (0.3 g) and saturated brine (8 mL) were placed in a vial (20 mL) and mixed.

[0204] (c) Analysis operating conditions

[0205] · SPME fiber: DVB / CAR / PDMS (Merck)

[0206] Film thickness 50 / 30 μm

[0207] Extraction temperature and time: 60 °C and 40 minutes

[0208] · GC / MS equipment: 7890GC / 5977AMS (Agilent Technologies, Inc.)

[0209] Inlet temperature and mode: 250 °C, split injection 1:5

[0210] Carrier gas: helium, 1 mL / min

[0211] Column: DB-WAX-UI

[0212] 0.25 mm × 30 m, film thickness; 0.25 μm

[0213] Oven: 40 °C and 5 minutes → 15 °C / minute → 250 °C and 10 minutes

[0214] Ion source temperature: 230 °C

[0215] Scan range: m / z 33 - 200

[0216] Analysis of free amino acids

[0217] (a) Analysis method: Ultra Performance Liquid Chromatography - Mass Spectrometry (UPLC / MS / MS)

[0218] (b) Preparation of analysis sample

[0219] Powdery sample: Prepare an aqueous solution (10% by mass) of the powdery sample

[0220] (c) Analysis operation conditions

[0221] · UPLC / MS / MS instrument: ACUITY UPLC-MSMS (TQD) (Waters)

[0222] Column: ACCQ-TAGTM ULTRA C18, 1.7 mm, 2.1 × 100 mm

[0223] Oven: 55 °C

[0224] Injection volume of sample: 10 μL

[0225] Solvent A: Dilute ACCQ TagUltraA 20-fold with ultrapure water and use

[0226] Solvent B: Use ACCQ TagUltraB as it is

[0227] Strong: 100% CAN

[0228] Weak, sealed: 10% CAN in MilliQ

[0229] · UPLC operation conditions: Inlet Method

[0230] Flow rate: 0.7 mL / min

[0231] 0 - 2 min: 90% diluent A, 2 - 10 min: 85% diluent A, 10 - 12.5 min: 0% diluent A, 12.5 - 16 min: 90% diluent A

[0232] · Analysis conditions for MS: MS Tune

[0233] MS mode: MSMS (ESI+ mode)

[0234] Capillary voltage: 3.5 kV

[0235] Desolvation temperature: 350 °C

[0236] Desolvation gas (N2): 800 L / h

[0237] Cone gas (N2): 250 L / h

[0238] Collision gas (Ar): 0.15 mL / min (9 mL / h)

[0239] · MS monitor: Monitoring time 0 - 10 min

[0240] HMB (mz / mz); 117.1 > 59.0, cone voltage 20 V

[0241] Collision energy 10 eV, dwell 0.2 s

[0242] HICA (mz / mz); 131.1 > 85.0, cone voltage 20 V

[0243] Collision energy 10 eV, dwell 0.4 s

[0244] 2H2MB (mz / mz); 117.1 > 71.0, cone voltage 20 V

[0245] Collision energy 10 eV, dwell 0.2 s

[0246] In the experimental examples described below, sensory evaluation was conducted according to the following method.

[0247] Sensory evaluation

[0248] (a) Panel: Experts (sensory evaluation experts) who have received in - house sensory evaluation training and regularly conduct sensory evaluation in their work

[0249] (b) Sensory evaluation test

[0250] Each expert placed the test samples (the samples treated with lactic acid bacteria (inventive samples) and the samples not treated with lactic acid bacteria (control samples)), adjusted to room temperature (25 ± 5 °C), into their mouths and swallowed them, and evaluated the protein odor (retronasally) felt in the area from the oral cavity to the nasal cavity and the refreshing aftertaste (reduction of unpleasant flavors) felt after swallowing the samples. According to the paired comparison method, the inventive samples were compared with the control samples to evaluate the differences (intensities). Details of the inventive samples and the control samples are described below.

[0251] For the evaluation of protein odor and refreshing aftertaste, the experts individually examined the flavor (protein odor and aftertaste) of the control samples in advance and discussed to unify the internal standards held by the group.

[0252] Each expert scored the protein odor and refreshing aftertaste according to the following criteria, and calculated the average value to produce a comprehensive evaluation.

[0253] Protein odor

[0254] 3: The protein odor is reduced compared to the control sample.

[0255] 2: The protein odor is present to the same extent as the control sample.

[0256] 1: The protein odor is increased compared to the control sample.

[0257] Refreshing aftertaste

[0258] 3: Compared to the control sample, there is no unpleasant aftertaste, and it feels very refreshing.

[0259] 2: The unpleasant aftertaste is present to the same extent as the control sample.

[0260] 1: Compared to the control sample, an unpleasant aftertaste is present, with less refreshing feeling.

[0261] Experimental Example 1: Manufacture and evaluation of liquid high-protein milk raw material treated with lactic acid bacteria using MPC as milk raw material

[0262] (1) Manufacture of liquid lactic acid bacteria-treated high-protein milk raw material

[0263] MPC was dissolved in warm water (60 °C) to prepare an MPC solution with a total solid content of 10% by mass (content of milk source protein in every 100 mass parts of total solid content: 80 mass parts). The MPC solution was subjected to heat sterilization treatment (to 95 °C) and then cooled (40 °C) to prepare a heat-sterilized MPC solution. A predetermined amount (10 6 to 10 8The lactic acid bacteria shown in Table 1 (cfu / ml) were mixed with the solution, and stirred and maintained at the temperature and for the time shown in Table 1 to prepare a lactic acid bacteria-treated MPC solution having the pH shown in Table 1. None of these lactic acid bacteria-treated MPC solutions formed curd, and they were in a liquid state. Subsequently, these lactic acid bacteria-treated MPC solutions were heated (to 60 °C) and then cooled (below 10 °C) to produce a liquid lactic acid bacteria-treated MPC (lactic acid bacteria-treated high-protein milk raw material). These products are hereinafter referred to as "lactic acid bacteria-treated milk raw materials" (invention samples 1-a to 1-f).

[0264] Table 1

[0265]

[0266] (2) Analysis of aroma components of the liquid lactic acid bacteria-treated high-protein milk raw material

[0267] Analysis of the aroma components of the lactic acid bacteria-treated milk raw materials (invention samples 1-a to 1-f) produced in Experimental Example 1(1) and the heat-sterilized MPC solution before lactic acid bacteria treatment (milk raw material not treated with lactic acid bacteria) (control sample) was performed according to headspace solid-phase microextraction by gas chromatography-mass spectrometry described above. The selected aroma components were dimethyldisulfide (DMDS) and dimethyltrisulfide (DMTS) as sulfur compounds (both are index substances for protein deterioration), nonanal (index substance for lipid deterioration), diacetyl (index substance for fermentation aroma), acetoin (3-hydroxy-2-butanone) (index substance for fermentation aroma), and δ-decalactone (index substance for milkiness).

[0268] The analysis values (area values in the chart) of each aroma component of the control sample were set to 1.0, and the analysis values of the aroma components of the lactic acid bacteria-treated milk raw materials (invention samples 1-a to 1-f) were calculated as relative values. Table 2 shows the results.

[0269] Table 2

[0270]

[0271] As shown in Table 2, compared with the liquid milk raw material not treated with lactic acid bacteria (control sample), the liquid lactic acid bacteria-treated milk raw materials (invention samples 1-a to 1-f) tended to have reduced levels of DMDS and DMTS as index substances for protein deterioration, and reduced levels of nonanal as an index substance for lipid deterioration. Compared with the control sample, invention samples 1-a to 1-f tended to have increased levels of diacetyl and acetoin as index substances for fermentation aroma. In addition, compared with the control sample, invention samples 1-a to 1-f tended to show almost no change in the level of δ-decalactone.

[0272] (3) Sensory evaluation of the high-protein milk raw material treated with liquid lactic acid bacteria

[0273] A panel of five experts evaluated the protein odor and refreshing aftertaste of the lactic acid bacteria-treated milk raw materials (invention samples 1-a to 1-f) produced in Experimental Example 1(1) according to the method described above. Table 3 shows the average scores of the five experts in the panel.

[0274] Table 3 Average scores of the five experts in the panel

[0275] Liquid milk raw material treated with lactic acid bacteria Protein odor Refreshing aftertaste Inventive sample 1-a 3 3 Inventive sample 1-b 3 3 Inventive sample 1-c 3 3 Inventive sample 1-d 3 3 Inventive sample 1-e 3 3 Inventive sample 1-f 2.6 2.6

[0276] As shown in Table 3, compared with the liquid milk raw material not treated with lactic acid bacteria (control sample), the liquid lactic acid bacteria-treated milk raw materials (invention samples 1-a to 1-f) were confirmed to have a reduced level of protein odor and a refreshing aftertaste. In addition, none of the invention samples 1-a to 1-f had an acidic taste.

[0277] From the results shown in Table 2, it can be inferred that the reduction of DMDS and DMTS, which are one of the causes of protein odor, and the increase of diacetyl and acetoin result in a masking effect, reducing the protein odor and providing a refreshing aftertaste.

[0278] Experimental Example 2: Manufacture and evaluation of powdered high-protein milk raw material treated with lactic acid bacteria using MPC as milk raw material

[0279] (1) Production of the powdered lactic acid bacteria-treated high-protein milk raw material

[0280] The invention samples 1-a and 1-b in the liquid lactic acid bacteria-treated MPC (lactic acid bacteria-treated high-protein milk raw material) produced in Experimental Example 1(1) and the MPC solution (milk raw material not treated with lactic acid bacteria, control sample) subjected to heat sterilization treatment before lactic acid bacteria treatment were spray-dried (inlet temperature: 180 to 185 °C, outlet temperature: 80 to 85 °C) using a spray dryer to produce powdered (solid) lactic acid bacteria-treated MPC (lactic acid bacteria-treated high-protein milk raw material, invention samples 2-a and 2-b) and powdered MPC not treated with lactic acid bacteria (control sample). Hereinafter, these products will be referred to as "powdered lactic acid bacteria-treated milk raw materials" (invention samples 2-a and 2-b) and "powdered milk raw materials not treated with lactic acid bacteria" (control sample).

[0281] (2) Analysis of the aroma components of the powdered lactic acid bacteria-treated milk raw material

[0282] In the same manner as in Experimental Example 1(2), the aroma components of the powdered lactic acid bacterium-treated milk raw materials (invention samples 2-a and 2-b) and the powdered non-lactic acid bacterium-treated milk raw materials (control samples) produced in Experimental Example 2(1) were analyzed by headspace solid-phase microextraction of the gas chromatography-mass spectrometry method described above. The analytical values (area values in the chart) of each aroma component of the control samples were set to 1.0, and the analytical values of the aroma components of invention samples 2-a and 2-b were calculated as relative values. Table 4 shows the results.

[0283] Table 4

[0284]

[0285] As shown in Table 4, compared with the powdered non-lactic acid bacterium-treated milk raw materials (control samples), the powdered lactic acid bacterium-treated milk raw materials (invention samples 2-a and 2-b) tended to have reduced levels of DMDS and DMTS, which are indicator substances for protein deterioration. Compared with the control samples, invention samples 2-a and 2-b tended to have increased levels of diacetyl and acetoin. In addition, compared with the control samples, invention samples 2-a and 2-b tended to show little change in the levels of nonanal and δ-decalactone.

[0286] The results of Experimental Example 1(2) and Experimental Example 2(2) show that treating high-protein milk raw materials with lactic acid bacteria tended to reduce the levels of DMDS and DMTS, which are indicator substances for protein deterioration, and tended to increase the levels of diacetyl and acetoin, which are indicator substances for fermentation odor. In addition, it was also confirmed that drying these liquid samples to prepare powdered (solid) samples did not affect the tendency for DMDS and DMTS to decrease and diacetyl and acetoin to increase.

[0287] (3) Analysis of Free Amino Acids in Powdered Lactic Acid Bacterium-Treated Milk Raw Materials

[0288] According to the ultra-high performance liquid chromatography-mass spectrometry method described above, the free amino acids (histidine (His), asparagine (Asn), serine (Ser), glutamine (Gln), glycine (Gly), arginine (Arg), aspartic acid (Asp), glutamic acid (Glu), threonine (Thr), alanine (Ala), proline (Pro), lysine (Lys), cysteine (Cys), tyrosine (Tyr), methionine (Met), isoleucine (Ile), valine (Val), leucine (Leu), phenylalanine (Phe), tryptophan (Trp), citrulline (Cit), γ-aminobutyric acid (GABA) and ornithine (Orn)) of the powdered lactic acid bacteria-treated milk raw materials (invention samples 2-a and 2-b) and the powdered non-lactic acid bacteria-treated milk raw materials (control samples) produced in Experimental Example 2(1) were analyzed. Tables 5-1 to 5-4 show the results.

[0289] Table 5-1

[0290]

[0291] Table 5-2

[0292]

[0293] Table 5-3

[0294]

[0295] Table 5-4

[0296]

[0297] As shown in Tables 5-1 to 5-4, it was confirmed that the powdered lactic acid bacteria-treated milk raw materials (invention samples 2-a and 2-b) generally had an increased amount of free amino acids compared to the powdered non-lactic acid bacteria-treated milk raw materials (control samples).

[0298] (4) Sensory evaluation of the powdered lactic acid bacteria-treated milk raw materials

[0299] The powdered lactic acid bacteria-treated milk raw materials (invention samples 2-a and 2-b) and the control samples produced in (1) above were prepared into aqueous solutions such that the total solid content in each solution was 10% by mass. A panel of five experts evaluated the protein odor and refreshing aftertaste of the invention samples 2-a and 2-b of these aqueous solutions by the paired comparison method with the control sample according to the method described above. Table 6 shows the average scores of the five experts in the panel.

[0300] Table 6 Average scores of the five experts in the panel

[0301] Powdered milk raw material treated with lactic acid bacteria Protein odor Refreshing aftertaste Inventive sample 2-a 3 3 Inventive sample 2-b 3 3

[0302] As shown in Table 6, compared with the powdery milk raw material not treated with lactic acid bacteria (control sample), the powdery milk raw material treated with lactic acid bacteria (invention samples 2-a and 2-b) was confirmed to have a reduced level of protein odor and a refreshing aftertaste. In addition, neither invention sample 2-a nor 2-b had a sour taste.

[0303] From the results shown in Table 4, it can be inferred that the reduction of DMDS and DMTS, which are one of the causes of protein odor, and the increase of diacetyl and acetoin result in a masking effect, reducing protein odor and providing a refreshing aftertaste.

[0304] Experimental Example 3: Manufacture and evaluation of liquid high-protein milk raw material treated with lactic acid bacteria using WPC as milk raw material evaluation

[0305] (1) Manufacture of a liquid lactic acid bacteria-treated high-protein milk raw material

[0306] WPC was dissolved in warm water (60 °C) to prepare a WPC solution with a total solid content of 10% by mass (content of milk source protein in every 100 parts by mass of the total solid content: 80 parts by mass). This WPC solution was subjected to heat sterilization treatment (to 70 °C) and then cooled (40 °C) to prepare a heat-sterilized WPC solution.

[0307] A predetermined amount (10 6 to 10 8 cfu / ml) of the lactic acid bacteria shown in Table 7 was mixed with this solution, and stirred and held at the temperature and for the time shown in Table 7 to prepare a lactic acid bacteria-treated WPC solution with the pH shown in Table 7. None of these lactic acid bacteria-treated WPC solutions formed curds, and they were in a liquid state. Subsequently, these lactic acid bacteria-treated WPC solutions were heated (to 60 °C) and then cooled (below 10 °C) to manufacture a liquid lactic acid bacteria-treated WPC (lactic acid bacteria-treated high-protein milk raw material). These products are hereinafter referred to as "lactic acid bacteria-treated milk raw materials" (invention samples 3-a to 3-f).

[0308] Table 7

[0309]

[0310] (2) Analysis of the aroma components of the liquid lactic acid bacteria-treated milk raw material

[0311] Based on the headspace solid-phase microextraction of the gas chromatography-mass spectrometry method described above, the aroma components of the lactic acid bacteria-treated milk raw materials (invention samples 3-a to 3-f) produced in Experimental Example 3(1) and the heat-sterilized WPC solution (milk raw material not treated with lactic acid bacteria) (control sample) before lactic acid bacteria treatment were analyzed in the same manner as in Experimental Example 1(2). Similar to Experimental Example 1(2), the following aroma components were selected: DMDS and DMTS (both are indicator substances for protein deterioration), nonanal (indicator substance for lipid deterioration), diacetyl (indicator substance for fermentation aroma), acetoin (indicator for fermentation aroma), and δ-decalactone (indicator substance for milkiness).

[0312] The analytical values (area values in the chart) of each aroma component of the control sample were set to 1.0, and the analytical values of the aroma components of invention samples 3-a to 3-f were calculated as relative values. Table 8 shows the results.

[0313] Table 8

[0314]

[0315] As shown in Table 8, compared with the liquid milk raw material not treated with lactic acid bacteria (control sample), the liquid lactic acid bacteria-treated milk raw materials (invention samples 3-a to 3-f) tended to have reduced levels of DMDS and DMTS as indicator substances for protein deterioration, and reduced levels of nonanal as an indicator substance for lipid deterioration. Compared with the control sample, invention samples 3-a to 3-f tended to have increased levels of diacetyl and acetoin as indicator substances for fermentation aroma. In addition, compared with the control sample, invention samples 3-a to 3-f tended to show little change in the level of δ-decalactone.

[0316] (3) Sensory evaluation of the liquid lactic acid bacteria-treated milk raw materials

[0317] In the same manner as in Experimental Example 1(3), a panel of five experts evaluated the protein odor and refreshing aftertaste of invention samples 3a to 3f according to the paired comparison method with the control sample. Table 9 shows the average scores of the five experts in the panel.

[0318] Table 9 Average scores of the five experts in the panel

[0319] Milk raw material treated with lactic acid bacteria Protein odor Refreshing aftertaste Inventive sample 3-a 3 3 Inventive sample 3-b 3 3 Inventive sample 3-c 3 3 Inventive sample 3-d 3 3 Inventive sample 3-e 3 3 Inventive sample 3-f 3 3

[0320] As shown in Table 9, compared with the liquid milk raw material not treated with lactic acid bacteria (control sample), the liquid lactic acid bacteria-treated milk raw materials (invention samples 3-a to 3-f) were confirmed to have reduced levels of protein odor and a refreshing aftertaste. In addition, invention samples 3-a, 3-c, 3-e, and 3-f did not have a sour taste, while invention samples 3-b and 3-d had a slight sour taste.

[0321] It can be inferred from the results shown in Table 8 that the reduction of DMDS and DMTS, which are one of the causes of protein odor, and the increase of diacetyl and acetoin result in a masking effect, reducing the protein odor and providing a refreshing aftertaste. It was also confirmed that when the pH after lactic acid bacteria treatment was 6 or higher, no sour taste was perceived, while when the pH was lower than 6, the sour taste became obvious.

[0322] Experimental Example 4: Manufacture and evaluation of powdered high-protein milk raw material treated with lactic acid bacteria using WPC as milk raw material

[0323] (1) Production of powdered lactic acid bacteria-treated high-protein milk raw material

[0324] Using a spray dryer, the invention sample 3-a in the liquid lactic acid bacteria-treated milk raw material (invention samples 3-a and 3-f) produced in Experimental Example 3(1) and the heat-sterilized WPC solution before lactic acid bacteria treatment (milk raw material not treated with lactic acid bacteria, control sample) were spray-dried (inlet temperature: 180 to 185 °C, outlet temperature: 80 to 85 °C) to produce powdered (solid) lactic acid bacteria-treated WPC (lactic acid bacteria-treated high-protein milk raw material, invention sample 4-a) and powdered milk raw material not treated with lactic acid bacteria (control sample). Hereinafter, these products will be referred to as "powdered lactic acid bacteria-treated milk raw material" (invention sample 4-a) and "powdered milk raw material not treated with lactic acid bacteria" (control sample), respectively.

[0325] (2) Analysis of aroma components of powdered lactic acid bacteria-treated milk raw material

[0326] The powdered lactic acid bacteria-treated milk raw material (invention sample 4-a) and the powdered milk raw material not treated with lactic acid bacteria (control sample) produced in Experimental Example 4(1) were prepared into aqueous solutions such that the total solid content in each solution was 10% by mass. In the same manner as in Experimental Example 1(2), the aroma components of these aqueous solutions were analyzed by headspace solid-phase microextraction according to the gas chromatography-mass spectrometry described above.

[0327] The analysis values (area values in the chart) of each aroma component of the control sample were set to 1.0, and the analysis values of the aroma components of invention sample 4-a were calculated as relative values. Table 10 shows the results.

[0328] Table 10

[0329]

[0330] As shown in Table 10, compared with the milk raw material not treated with lactic acid bacteria (control sample), the powdered milk raw material treated with lactic acid bacteria (invention sample 4-a) tended to have reduced levels of DMDS and DMTS as index substances for protein degradation. Compared with the control sample, invention sample 4-a tended to have increased levels of diacetyl and acetoin. In addition, compared with the control sample, invention sample 4-a showed little change in the level of δ-decalactone.

[0331] The results of Experimental Example 3(2) and Experimental Example 4(2) showed that treating high-protein milk raw material with lactic acid bacteria tended to reduce the levels of DMDS and DMTS as index substances for protein degradation, and tended to increase the levels of diacetyl and acetoin as index substances for fermentation odor. In addition, it was confirmed that drying these liquid samples to prepare powdered (solid) samples did not significantly affect the tendency of DMDS and DMTS to decrease and diacetyl and acetoin to increase.

[0332] (3) Analysis of free amino acids in powdered milk raw material treated with lactic acid bacteria

[0333] According to ultra-high performance liquid chromatography-mass spectrometry, the free amino acids (histidine (His), asparagine (Asn), serine (Ser), glutamine (Gln), glycine (Gly), arginine (Arg), aspartic acid (Asp), glutamic acid (Glu), threonine (Thr), alanine (Ala), proline (Pro), lysine (Lys), cysteine (Cys), tyrosine (Tyr), methionine (Met), isoleucine (Ile), valine (Val), leucine (Leu), phenylalanine (Phe), tryptophan (Trp), citrulline (Cit), and γ-aminobutyric acid (GABA)) in invention sample 4-a and the control sample prepared in Experimental Example 4(1) were analyzed. Tables 11-1 to 11-4 show the results.

[0334] Table 11-1

[0335]

[0336] Table 11-2

[0337]

[0338] Table 11-3

[0339]

[0340] Table 11-4

[0341]

[0342] As shown in Tables 11-1 to 11-4, it was confirmed that the powdered milk raw material treated with lactic acid bacteria (invention sample 4-a) generally had an increased amount of free amino acids compared to the powdered milk raw material not treated with lactic acid bacteria (control sample).

[0343] (4) Sensory evaluation of the powdered milk raw material treated with lactic acid bacteria

[0344] The powdered milk raw material treated with lactic acid bacteria (invention sample 4a) and the control sample prepared in (1) above were made into aqueous solutions such that the total solid content in each solution was 10% by mass. A panel of five experts used these aqueous solutions to evaluate the protein odor and refreshing aftertaste of invention sample 4-a using the paired comparison method with the control sample according to the method described above. Table 12 shows the average scores of the five experts in the panel.

[0345] Table 12 Average scores of the five experts in the panel

[0346] Powdered milk raw material treated with lactic acid bacteria Protein odor Refreshing aftertaste Inventive sample 4-a 3 3

[0347] As shown in Table 12, compared to the powdered milk raw material not treated with lactic acid bacteria (control sample), the powdered milk raw material treated with lactic acid bacteria (invention sample 4-a) had a reduced level of protein odor and had a refreshing aftertaste. In addition, invention sample 4-a had almost no sour taste.

[0348] From the results shown in Table 10, it can be inferred that the reduction of DMDS and DMTS, which are one of the causes of protein odor, and the increase of diacetyl and acetoin led to a masking effect, reducing the protein odor and providing a refreshing aftertaste.

[0349] Experimental Example 5: Manufacture and evaluation of high-protein milk beverage containing powdered milk raw material treated with lactic acid bacteria

[0350] (1) Manufacture of high-protein milk beverages

[0351] High-protein milk beverages (invention beverage and control beverage) were manufactured by adding the powdered milk raw material treated with lactic acid bacteria (invention sample 2-a) or the powdered milk raw material not treated with lactic acid bacteria (control sample) prepared in Experimental Example 2. Specifically, the invention beverage and the control beverage were manufactured as described below.

[0352] (1-1) Manufacture of the invention beverage

[0353] Mix the inventive sample 2-a and concentrated skim milk (total solid content: about 30% by mass) so that the protein content is about 8% by mass to prepare a preparation liquid. Subsequently, add baking soda (sodium bicarbonate) to the preparation liquid and adjust the pH (pH = 6.7) so that the preparation liquid has the same pH as the control beverage described below. Then heat the preparation liquid (65 °C) and homogenize it (first-stage pressure: 10 MPa, second-stage pressure: 5 MPa), then heat-sterilize it (to 90 °C), and subsequently cool it (below 10 °C) to produce the inventive beverage (protein content: 8% by mass).

[0354] (1-2) Preparation of the control beverage

[0355] Mix the control sample and concentrated skim milk (total solid content: about 30% by mass) so that the total protein content is about 8% by mass to prepare a preparation liquid. Then heat the preparation liquid (65 °C) and homogenize it (first-stage pressure: 10 MPa, second-stage pressure: 5 MPa), then heat-sterilize it (to 90 °C), and subsequently cool it (below 10 °C) to produce the control beverage (protein content: 8% by mass).

[0356] (2) Sensory evaluation of the inventive beverage

[0357] A panel of 15 experts evaluated the protein odor, refreshingness (refreshing aftertaste), fresh milk aroma, and heated milk aroma of the inventive beverage according to the paired comparison method with the control beverage.

[0358] The phrase "fresh milk aroma" refers to the original flavor of milk that can be felt from unheated (unsterilized) cow's milk (raw milk). In addition, the phrase "heated milk aroma" refers to the burnt flavor detected in heated (sterilized) cow's milk. The experts in the panel confirmed these flavors in advance and discussed them to unify their internal standards. According to the following criteria, each expert scored the protein odor, refreshingness (refreshing aftertaste), fresh milk aroma, and heated milk aroma; then, the average score was calculated to determine the comprehensive evaluation.

[0359] Protein odor

[0360] 3: Compared with the control sample, the protein odor is reduced.

[0361] 2: Compared with the control sample, the protein odor is present to the same extent.

[0362] 1: Compared with the control sample, the protein odor is increased.

[0363] Refreshing aftertaste

[0364] 3: Compared with the control sample, there is no unpleasant aftertaste and it feels very refreshing.

[0365] 2: Compared with the control sample, the unpleasant aftertaste exists to the same extent.

[0366] 1: Compared with the control sample, the unpleasant aftertaste exists and has less refreshing feeling.

[0367] Fresh milk aroma

[0368] 3: Compared with the control sample, the fresh milk aroma is strong.

[0369] 2: Compared with the control sample, the fresh milk aroma exists to the same extent.

[0370] 1: Compared with the control sample, the fresh milk aroma is weak.

[0371] Heated milk aroma

[0372] 3: Compared with the control sample, the heated milk aroma is weak.

[0373] 2: Compared with the control sample, the heated milk aroma exists to the same extent.

[0374] 1: Compared with the control sample, the heated milk aroma is strong.

[0375] Average score of 15 experts in Group 13 of Table 1

[0376] Milk beverage treated with lactic acid bacteria Protein odor Refreshing aftertaste Fresh milk aroma Heated milk aroma Inventive beverage 2.5 2.1 2.3 2.4

[0377] As shown in Table 13, compared with the control sample, the inventive beverage has a reduced level of protein odor, a refreshing aftertaste, a strong fresh milk aroma and a reduced heated milk aroma.

Claims

1. A method for manufacturing a high-protein milk raw material, comprising the following steps: (1) preparing a milk fluid from a milk raw material, the milk fluid having a total solid content of 5 to 15% by mass and the content of milk-derived protein being 50 parts by mass or more per 100 parts by mass of the total solid content, and (2) adding lactic acid bacteria to the milk fluid and maintaining the milk fluid containing the lactic acid bacteria until a pH in the range of 5.2 to 6.5 is reached, thereby obtaining a lactic acid bacteria-treated milk fluid having a pH in the said range.

2. The method for manufacturing a high-protein milk raw material according to claim 1, further comprising the step of (3-1) concentrating the lactic acid bacteria-treated milk fluid or concentrating and drying the lactic acid bacteria-treated milk fluid.

3. The method for manufacturing a high-protein milk raw material according to claim 1, further comprising the step of (3-2) drying the lactic acid bacteria-treated milk fluid.

4. The method for manufacturing a high-protein milk raw material according to any one of claims 1 to 3, wherein the milk fluid contains whey protein as the milk-derived protein but does not contain casein.

5. The method for manufacturing a high-protein milk raw material according to any one of claims 1 to 3, wherein the milk fluid contains casein or casein and whey protein as the milk-derived protein, the step (2) includes maintaining the milk fluid containing the lactic acid bacteria until a pH in the range of 6.0 to 6.5 is reached, thereby obtaining a lactic acid bacteria-treated milk fluid having a pH in the said range.

6. The manufacturing method according to claim 4, wherein the high-protein milk raw material is at least one member selected from the group consisting of whey protein concentrate (WPC) and whey protein isolate (WPI).

7. The manufacturing method according to claim 5, wherein the high-protein milk raw material is at least one member selected from the group consisting of milk protein concentrate (MPC), milk protein isolate (MPI), and micellar casein concentrate (MCC).

8. A liquid lactic acid bacteria-treated high-protein milk raw material, comprising 50 parts by mass or more of milk-derived protein per 100 parts by mass of the total solid content, the lactic acid bacteria-treated high-protein milk raw material contains at least dead cells of lactic acid bacteria, diacetyl, and 3-hydroxy-2-butanone, the lactic acid bacteria-treated high-protein milk raw material has a pH in the range of 5.2 to 6.

5.

9. The lactic acid bacteria-treated high-protein milk raw material according to claim 8, wherein the lactic acid bacteria-treated high-protein milk raw material contains whey protein as the milk-derived protein but does not contain casein.

10. The lactic acid bacteria-treated high-protein milk raw material according to claim 8, wherein the lactic acid bacteria-treated high-protein milk raw material contains casein or casein and whey protein as the milk-derived protein, and the lactic acid bacteria-treated high-protein milk raw material has a pH in the range of 6.0 to 6.

5.

11. A semi-solid or solid lactic acid bacteria-treated high-protein milk raw material, which is obtained by concentrating and / or drying the liquid lactic acid bacteria-treated high-protein milk raw material according to any one of claims 8 to 10.

12. A method for manufacturing a food or drink, which comprises a step of adding the high-protein milk raw material obtained by the manufacturing method according to any one of claims 1 to 7 to the food or drink.

13. A food or drink, which comprises the lactic acid bacteria-treated high-protein milk raw material according to any one of claims 8 to 11.

14. A method for improving the flavor of a high-protein milk raw material, which comprises the following steps: (1) preparing a milk fluid from the milk raw material, the total solid content of the milk fluid being 5 to 15% by mass and the content of milk-derived protein being 50 parts by mass or more per 100 parts by mass of the total solid content, and (2) adding lactic acid bacteria to the milk fluid and maintaining the milk fluid containing the lactic acid bacteria until a pH within the range of 5.2 to 6.5 is reached, thereby obtaining a lactic acid bacteria-treated milk fluid having a pH within the said range.

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