JP7701135B2 - Fermented milk - Google Patents

Description

The present invention relates to fermented milk. More specifically, the present invention relates to static fermented milk containing a high concentration of protein and a method for producing the same.

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

Patent Document 1 aims to provide a method for producing fermented milk that contains a high concentration of protein with excellent flavor and texture, and as a means for solving this problem, it discloses a method for producing fermented milk that is characterized by blending skim milk powder, whey protein concentrate, and milk protein concentrate so that the protein ratio is 5 to 10% by mass, and when the total protein is taken as 100%, the protein contained in the skim milk powder is 20 to 60% by mass, the protein contained in the whey protein concentrate is 20 to 30% by mass, and the protein contained in the milk protein concentrate is 20 to 60% by mass.

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

Patent Document 3 aims to provide a solid yogurt that maintains its shape and water retention and has a good mouthfeel even when deterioration occurs due to storage conditions such as temperature rise and physical irritation during product delivery or storage, and a method for producing the same. It discloses a solid yogurt that contains substantially non-aggregating denatured protein spherical particles or aggregates thereof and gelatin, and a method for producing yogurt by inoculating and culturing lactic acid bacteria into a dairy raw material, the method comprising the step of adding substantially non-aggregating denatured protein spherical particles or aggregates thereof and gelatin before or after the culturing step.

International Publication No. 2017-029802 Japanese Patent Application Publication No. 11-28056 JP 2002-238452 A

However, in addition to the fermented milk and the methods for producing the same disclosed in Patent Documents 1 to 3, there has been a demand for a new still-set fermented milk that is high in protein but has low hardness and few curd particles, and a method for producing the same.
In view of the above, an object of the present invention is to provide an unprecedented novel static fermented milk with high protein content and a method for producing the same.

The present invention provides an invention including the following configuration as a means for solving the above problems.
[1] Fermented milk containing more than 3.4% by weight and less than 7% by weight of protein, having a hardness of 20 gf to 60 gf, and having 0 to 500 curd grains per 100 g.
[2] A method for producing fermented milk, comprising the steps of: adjusting the amount of protein in the fermented milk so that the protein content is greater than 3.4% by weight and less than 7% by weight; and adjusting the amount of microparticulated whey protein so that the microparticulated whey protein content is 10% by weight or more and 80% by weight or less relative to the protein.
[3] To satisfy at least one of the following conditions (a), (b), and (c):
(a) the total protein content is 3.4% by weight or more but less than 7.0% by weight;
(b) the amount of protein derived from microparticulated whey protein is 0.01% by weight or more;
(c) the amount of protein derived from the microparticulated whey protein relative to the total protein amount is 0.10 to 0.80;
The method for producing fermented milk according to [2], further comprising a step of adjusting the total protein amount in the fermented milk and/or the protein amount derived from the microparticulated whey protein.

The present invention provides a static fermented milk that is high in protein but has low hardness and few curd particles, and a method for producing the same.

(Fermented milk)
In the present invention, "fermented milk" refers to milk or other animal milk such as cow's milk or milk or the like containing the same or higher non-fat milk solids as cow's milk, fermented with any one or a combination of lactic acid bacteria, bifidobacteria, and yeast. Fermented milk can be classified according to its properties and production method into 1) static fermented milk, 2) stirred fermented milk, and 3) liquid fermented milk. The static fermented milk 1) is called hard type fermented milk, and has a pudding-like texture that is filled into a retail container and fermented, and is produced, for example, as follows. First, a fermentation mix prepared by mixing and dissolving raw materials such as milk, dairy products, and sucrose is homogenized, sterilized, and cooled, and then inoculated with a lactic acid bacteria starter, filled into a container and sealed, and fermented in a culture room or fermentation tunnel. When the appropriate acidity is reached, the mixture is immediately cooled to 10°C or less to terminate the fermentation and produce the final product. 2) Stirred fermented milk is also called soft fermented milk, and is prepared by adding a lactic acid bacteria starter to a fermentation mix, fermenting in a tank, crushing the curds, and filling a container to produce the final product. 3) Liquid fermented milk is prepared by fermenting a fermentation mix in the same manner as stirred fermented milk, crushing the curds, and homogenizing the liquid fermented milk to produce the final product. Of the above, the present invention includes 1) static fermented milk.

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

(Protein content)
In the present invention, "high-protein fermented milk" refers to a milk containing more than 3.4% by weight of protein, which is contained in normal cow's milk. There is no limit to the amount of protein in the static fermented milk of the present invention, but a protein content of more than 3.4% by weight and less than 7% by weight is preferable in terms of reducing the number of curd particles, while a protein content of 4% to less than 7% by weight, or 5% to less than 7% by weight, can provide static fermented milk that is high in protein but has low hardness and few curd particles.

Next, the total protein amount in the fermented milk and the protein amount derived from the microparticulated whey protein will be described.
(a) The total protein amount is preferably 3.4% by weight or more and less than 7.0% by weight, (b) The protein amount derived from the microparticulated whey protein is preferably 0.01% by weight or more, and (c) The protein amount derived from the microparticulated whey protein relative to the total protein amount is preferably 0.10 to 0.80. It is preferable to satisfy at least one of the above conditions (a), (b), and (c), more preferably satisfy two, and particularly preferably satisfy three. Furthermore, (a2) The total protein amount is preferably 4.0% by weight or more and less than 7.0% by weight, (b2) The protein amount derived from the microparticulated whey protein is preferably 0.5% by weight or more, and (c2) The protein amount derived from the microparticulated whey protein relative to the total protein amount is preferably 0.20 to 0.80. It is preferable to satisfy at least one of the above conditions (a2), (b2), and (c2), more preferably satisfy two, and particularly preferably satisfy three.

(hardness)
The fermented milk of the present invention can have any desired hardness, but from the standpoints of flavor, such as feel on the tongue, smoothness of texture, and product transportation resistance, the hardness is preferably 20 to 60 gf, more preferably 20 to 55 gf, and even more preferably 20 to 50 gf.

(Number of cards)
The number of curd grains in the fermented milk of the present invention is preferably 0 to 500 grains, more preferably 0 to 450 grains, and even more preferably 0 to 400 grains, per 100 g of fermented milk, in that the curd grains are less noticeable when mixed with fruit sauce, jam, or the like.

(fat amount)
There is no particular limitation on the fat content of the fermented milk of the present invention, but since the present invention relates to high-protein fermented milk, in terms of the total solid content of the fermented milk, low-fat (about 2% by weight or less) or fat-free (substantially 0% by weight) fermented milk is preferred.

(Method of measuring hardness)
The hardness of the fermented milk of the present invention is defined by the maximum load of the fermented milk. The maximum load can be measured by a two-time penetration test using a texture analyzer on the fermented milk. Specifically, the maximum load of the fermented milk can be measured by subjecting a sample adjusted to 10°C to the texture analyzer under the conditions of Test Speed: 1 mm/s, Penetration Distance: 10 mm, Jig: Resin cylindrical probe with a diameter of 16 mm and a height of 25 mm, and Mode: Compression. The size of the sample may be such that the height of the penetration distance is 10 mm or more and the diameter is 16 mm or more.

(Method of measuring number of curd particles)
The number of curd particles in the fermented milk of the present invention can be measured by the following procedure. 100 g of fermented milk is collected in a cup and stirred for 1 minute at 200 rpm with a stirrer equipped with a motor and four blades. The fermented milk after stirring is adjusted to 1/4, or 25 g, and tap water is added to make the total amount 200 g. This is stirred with a stirrer at 400 rpm for 30 seconds, filtered through a sieve with 1 mm openings, and the number of particles captured on the sieve is counted. The number of particles obtained by the measurement is multiplied by 4 to obtain the number of curd particles.

(Manufacturing method)
(raw materials)
(Microparticulated whey protein)
The fermented milk of the present invention contains particulate whey protein. The particulate whey protein refers to a precipitate fraction obtained by subjecting a solution containing whey protein to a physicochemical treatment in which the whey protein aggregates, followed by centrifugation.
The particulate whey protein may be a commercially available milk protein material, such as Simplex 100 (manufactured by CPKelko) or WPC 550 (manufactured by Fonterra).
Alternatively, it may be prepared from a solution containing whey protein by using a known method, for example, the method described in International Journal of Food Science & Technology, 34(5-6), pp. 523-525.
The degree of denaturation of the whey protein contained in the particulate whey protein material is 70% or more, more preferably 80% or more, and even more preferably 90% or more. The median diameter of the particulate whey protein is preferably 5 μm or less, more preferably 4 μm or less, and most preferably 3 μm or less. Heating and homogenization treatment are performed as necessary to achieve such a degree of denaturation and median diameter.
The particulate whey protein material may be blended in such a way that the amount of protein derived from the particulate whey protein material in the static fermented milk is 0.01% by weight or more, preferably 0.5% by weight or more, more preferably 1% by weight or more, even more preferably 2% by weight or more, and even more preferably 3% by weight or more.
In addition, the ratio of the amount of microparticulated whey protein to the total protein contained in the static fermented milk of the present invention is preferably 0.10 to 0.80, more preferably 0.20 to 0.70, and most preferably 0.30 to 0.60, in view of the reduction in the number of curd particles.
When adjusting the hardness, WPI (Whey Protein Isolate: WPI) and/or WPC (Whey Protein Concentrate: MPC) can be added. When the amount of WPI is less than 1% by weight of protein based on the fermented milk, it is possible to suppress a decrease in hardness without causing an excessive increase in the number of curd particles.

(manufacturing process)
A specific embodiment of the method for producing fermented milk of the present invention will be described below.
Raw milk, skim milk powder, MPC (Milk Protein Concentrate: MPC), WPC, WPI, microparticulated whey protein, and other raw materials generally used in the production of fermented milk are weighed and dissolved in a predetermined amount, and then homogenized and sterilized. The order of homogenization and sterilization is not specified. Examples of homogenization conditions include a temperature of 50 to 70°C and a homogenization pressure of 50 to 500 kg/ ^cm2 , and examples of sterilization conditions include a temperature of 80 to 95°C and a holding time of 2 seconds to 10 minutes, but are not limited thereto.
Lactic acid bacteria are added to the cooled raw material liquid (mix) and filled into a container. When lactic acid bacteria are added, fermentation conditions can be 30 to 40°C for 3 to 20 hours, and the end point of fermentation can be when the lactic acid acidity of the mix reaches 0.7 to 1.3%. Lactic acid bacteria used for fermentation can be Lactobacillus bulgaricus (L. bulgaricus), Streptococcus thermophilus (S. thermophilus), etc., but there is no particular limitation as long as it is a lactic acid bacteria starter commonly used in fermented milk production. After fermentation is completed, the container is cooled to 10°C or less to obtain stationary fermented milk.

(Degree of Modification)
The degree of denaturation of whey protein can be measured by the following method. 0.4 g of sample, 0.8 g of distilled water at 40° C., and 40 μL of 10% by volume acetic acid are dispensed into a microtube, stirred well, and then held for 10 minutes. Then, 40 μL of 1M sodium acetate and 0.72 g of distilled water are dispensed into the microtube, and stirred well again. After leaving it for 1 hour, centrifuge at 3000 g for 5 minutes. The amount of insoluble whey protein precipitated by this treatment is considered to be denatured whey protein, and the amount of soluble whey protein contained in the supernatant is considered to be undenatured whey protein. In addition, after performing the above treatment by replacing 10% by volume hydrochloric acid and 1M sodium acetate with distilled water, the amount of soluble protein contained in the supernatant is considered to be the total amount of whey protein. At this time, the degree of denaturation of whey protein contained in the whey protein base is expressed by the following formula. In addition, ThermoFisher's BCAProtein Assay Kit was used for protein quantification.
Denaturation degree = denatured whey protein / total whey protein = (1 - whey protein in supernatant) / total whey protein)

(Median diameter)
The median diameter of the microparticulated whey protein can be measured by a particle size distribution measuring device such as a laser diffraction particle size distribution measuring device, a laser diffraction/scattering particle size distribution measuring device, an image analysis particle size distribution measuring device, a precision particle size distribution measuring device, a real-time zeta potential/nanoparticle size measuring device, a dynamic light scattering (DLS) particle size distribution measuring device, an analytical ultracentrifuge system, etc. The particle diameter corresponding to 50% of the obtained cumulative distribution curve on a volume basis is called the median diameter, and is also called the so-called 50% particle diameter, 50% diameter, d50, etc.

Next, the present invention will be specifically explained by showing examples. However, the present invention should not be interpreted as being limited to the examples.

(Preparation of particulate whey protein)
The UF concentrate of cheddar cheese whey was heated and sheared by the method described in International journal of food science & technology, 34 (5-6), p. 523-525. The resulting whey suspension was then spray-dried to obtain a powder of microparticulated whey protein (hereinafter, also referred to as MPW in the table). The microparticulated whey protein powder had a whey protein concentration of 79%, a degree of whey protein denaturation of 90%, and a median diameter of whey protein of 1.5 μm. The resulting microparticulated whey protein powder was used in the test described in the next section.

(Examples 1 to 8, Comparative Examples 1 and 2)
According to the formulation shown in Table 1, the static fermented milk of Examples 1 to 8 and Comparative Examples 1 to 2 was produced by the following preparation method. The raw materials were mixed and dissolved with 65°C blended water in a homogenizer to prepare a mix. The mix was reheated to 65°C, homogenized at a homogenizing pressure of 140 kg/ ^cm2 , and then heat-sterilized at 95°C for 30 seconds. It was then cooled to 40°C, and 1.5% by weight of Lactobacillus bulgaricus and 0.15% by weight of Streptococcus thermophilus were added and filled into a container. The container filled with the mix was fermented in a fermentation chamber set at 40°C, and when the acidity reached 1.00%, it was cooled to 5°C to obtain static fermented milk. In addition, the lipid content was 0.5% by weight or less in all of Examples 1 to 8 and Comparative Examples 1 to 2.

Table 2 shows the properties of Examples 1 to 8 and Comparative Examples 1 and 2. Note that the hardness and number of curd particles of the static fermented milk at a product temperature of 10°C one week after preparation were used as the property values of static fermented milk.

In Examples 1 to 8, the hardness was 20 to 60 gf, the number of curd particles was 500 or less per 100 g, and the structure had a moderate hardness and the increase in the number of curd particles was suppressed. In Comparative Example 1, the hardness was 60 gf or more, and the structure was hardened. In Comparative Example 2, the mix did not gel, and did not become a static fermented milk.
In other words, the static fermented milk, which is characterized by a total protein content of 3.4% or more and less than 7.0%, a protein content derived from microparticulated whey protein of 0.01% or more, and an amount of protein derived from microparticulated whey protein relative to the total protein content of 0.10 to 0.80, had an appropriate hardness and had a reduced number of curd particles.

Claims (3)

Contains 4% or more and less than 7% by weight of protein;
The hardness is 20 gf or more and 60 gf or less, and the number of curd particles is 0 to 500 per 100 g.
The protein comprises a particulate whey protein having a median diameter of 5 μm or less ;
A static fermented milk characterized by the above. adjusting the protein content in the fermented milk to 5% by weight or more and less than 7% by weight;
A step of adjusting the amount of particulate whey protein so that the particulate whey protein is 10% by weight or more and 80% by weight or less relative to the protein;
A method for producing stationary fermented milk, comprising:
The above-mentioned production method, wherein the median diameter of the microparticulated whey protein is 5 μm or less . Further, a step of adjusting the amount of protein derived from the particulate whey protein in the fermented milk so that the amount of the protein derived from the particulate whey protein in the fermented milk satisfies 0.01% by weight or more;
The method for producing static fermented milk according to claim 2, further comprising the steps of: