Fermented food, method for producing same, and method for improving viability of bifidobacteria

Abstract

A fermented food obtained by fermenting a starting material composition comprising bifidobacteria, a bacterium belonging to the genus Lactococcus, and an iron-containing compound has excellent bifidobacteria viability.

Description

TECHNICAL FIELD

[0001] The present application relates to a fermented food, a method for producing a fermented food, and a method for improving the viability of Bifidobacterium.

[0002] This application claims priority based on Japanese Patent Application No. 2023-132859 filed in Japan on August 17, 2023, and the content thereof is incorporated herein. BACKGROUND

[0003] Bifidobacterium bacteria (hereinafter also referred to as "Bifidobacterium") are representative of useful intestinal bacteria (also referred to as "probiotics") known to have various physiological functions such as infection defense from pathogenic bacteria, and the demand for foods containing live Bifidobacterium is increasing.

[0004] However, Bifidobacterium has poor proliferative ability in milk medium, and in addition, has poor viability under acidic conditions, and thus, it is a problem in the production of fermented foods to make Bifidobacterium survive in fermented foods.

[0005] To address the problem, a method for improving the viability of Bifidobacterium in fermented milk by using bacteria belonging to Bifidobacterium and Lactococcus lactis as lactic acid bacteria for fermentation is proposed in Patent Literature 1.

[0006] PRIOR ART DOCUMENTS

[0007] PATENT LITERATURE

[0008] Patent Literature 1: Japanese Patent No. 4772131 SUMMARY

[0009] PROBLEMS TO BE SOLVED BY THE INVENTION

[0010] It is desirable to preferentially improve the viability of Bifidobacterium, and further improve the viability of Bifidobacterium than the method described in Patent Literature 1.

[0011] An object of the present application is to provide a fermented food in which the viability of Bifidobacterium is excellent.

[0012] SOLUTION TO PROBLEM

[0013] The present application has the following modes.

[0014] [1] A fermented food comprising Bifidobacterium, Lactococcus bacteria, and an iron-containing compound.

[0015] [2] The fermented food according to [1], wherein the iron content per 100 g of the aforementioned fermented food is 0.3 mg or more.

[0016] [3] The fermented food according to [1] or [2], wherein the aforementioned iron-containing compound comprises non-heme iron.

[0017] [4] The fermented food according to [3], wherein the aforementioned iron-containing compound contains one or more selected from the group consisting of ferric pyrophosphate, ferrous citrate, and ferric ammonium citrate.

[0018] [5] The fermented food according to any one of [1] to [4], wherein the content of the viable bacteria of the aforementioned bifidobacterium per 100 g of the aforementioned fermented food is 1 x 10 8 cfu or more.

[0019] [6] The fermented food according to any one of [1] to [5], wherein the aforementioned bifidobacterium contains one or more selected from the group consisting of Bifidobacterium longum and Bifidobacterium breve.

[0020] [7] The fermented food according to any one of [1] to [6], wherein the aforementioned lactococcus bacterium contains Lactococcus lactis.

[0021] [8] The fermented food according to any one of [1] to [7], wherein the aforementioned fermented food is fermented milk.

[0022] [9] A method for producing a fermented food, comprising a step of fermenting a raw material composition containing a bifidobacterium, a lactococcus bacterium, and an iron-containing compound.

[0023]

[10] A method for improving the viability of a bifidobacterium, which is a method for improving the viability of a bifidobacterium in a fermented product obtained by fermenting a raw material composition containing a bifidobacterium,

[0024] the method fermenting a raw material composition containing a bifidobacterium, a lactococcus bacterium, and an iron-containing compound.

[0025] Effects of the Invention

[0026] According to the present invention, a fermented food with excellent viability of bifidobacterium can be obtained. BRIEF DESCRIPTION OF DRAWINGS

[0027] Fig. 1 A graph showing the results of measurement of the bifidobacterium after storage in Examples 5 to 7.

[0028] Fig. 2 A graph showing the results of measurement of the bifidobacterium after storage in Examples 8 to 10.

[0029] Fig. 3 A graph showing the results of measurement of the bifidobacterium after storage in Examples 11 to 14.

[0030] Fig. 4 A graph showing the results of measurement of the bifidobacterium after storage in Examples 15 to 19.

[0031] Fig. 5 The graph shows the results of the determination of Bifidobacterium after preservation in Examples 15, 20-23.

[0032] Fig. 6 A graph showing the results of the determination of Bifidobacterium after preservation in Examples 24-27. Detailed Implementation

[0033] Fermented foods, as used in this specification, refer to foods containing fermented products obtained by fermenting a substrate with fermenting bacteria. Among fermented foods, fermented milk refers to a food made into a paste or liquid state by fermenting milk or milk containing an equal or greater amount of non-fat milk solids using fermenting bacteria. Here, "milk" can be milk from mammals, and examples include milk from cows, sheep, or goats. Milk from cows (i.e., cow's milk) is preferred.

[0034] The fermented food of the present invention contains Bifidobacterium, Lactococcus bacteria and iron-containing compounds.

[0035] Bifidobacteria are bacteria belonging to the genus *Bifidobacterium*. Known types of Bifidobacteria can be used in fermented foods. Examples include *Bifidobacterium longum* subsp. *longum*, *Bifidobacterium breve*, *Bifidobacterium longum* subsp. *infantis*, *Bifidobacterium bifidum*, *Bifidobacterium lactis* (*Bifidobacterium animalis* subsp. *lactis*), *Bifidobacterium animalis* (*Bifidobacterium animalis* subsp. *animalis*), and *Bifidobacterium adolescentis*. It should be noted that *Bifidobacterium longum* subsp. *longum* is sometimes simply referred to as *Bifidobacterium longum*. In addition, Bifidobacterium longum subsp. infantis is sometimes simply referred to as Bifidobacterium infantis.

[0036] In this invention, *Bifidobacterium longum* subsp. *longum* and *Bifidobacterium breve* are preferred.

[0037] In addition, among them, Bifidobacterium longum subsp. BB536 (NITE BP-02621, hereinafter also referred to as "NITEBP-02621") and Bifidobacterium breve MCC1274 (FERM BP-11175, hereinafter also referred to as "FERM BP-11175") are preferred.

[0038] One type of Bifidobacterium can be used, or two or more types can be used in combination.

[0039] The bacteria assigned the accession number NITE BP-02621 was internationally deposited on January 26, 2018, at the Patent Microbial Collection Center of the Technical Base for Product Evaluation (Room 122, 2-5-8 Kazusa-Kamazu, Kisarazu City, Chiba Prefecture, Japan 292-0818, Japan) under the accession number NITE BP-02621, based on the Budapest Treaty. This bacterium is identical to *Bifidobacterium longum* subsp. BB536.

[0040] The bacteria assigned the accession number FERM BP-11175 was internationally deposited on August 25, 2009, at the Patent Biology Collection Center of the National Institute of Advanced Industrial Science and Technology (now the Patent Biology Collection Center of the Technical Base for Product Evaluation, 2-5-8 Kazusa-Kamazu, Kisarazu City, Chiba Prefecture, Japan 292-0818, Japan) under the Budapest Treaty. This bacterium is the same as *Bifidobacterium breve* MCC1274.

[0041] Lactococcus bacteria can be those known to be found in fermented foods. Examples include Lactococcus lactis subsp. lactis, Lactococcus lactis subsp. cremoris, and Lactococcus plantarum.

[0042] It should be noted that *Lactococcus lactis* subsp. *lactis* is sometimes simply referred to as *Lactococcus lactis*. Additionally, *Lactococcus lactis* subsp. *cremoris* is sometimes simply referred to as *Lactococcus cremoris*.

[0043] In this invention, *Lactococcus lactis* subsp. *lactococcus* is preferred.

[0044] As subspecies of Lactococcus lactis, the following can be listed: Lactococcus lactis NITE BP-1204, Lactococcus lactis NITE BP-1205, Lactococcus lactis MCC852 (FERM BP-10742), Lactococcus lactis MCC857 (FERM BP-10757), Lactococcus lactis MCC859 (FERM BP-10744), Lactococcus lactis MCC865 (FERM BP-10745), and Lactococcus lactis MCC866 (FERM BP-10746).

[0045] In addition, the preferred strain is Lactococcus lactis subsp. NITE BP-1204 (hereinafter also referred to as "NITE BP-1204").

[0046] The bacteria assigned the accession number NITE BP-1204 and the bacteria assigned the accession number NITE BP-1205 were internationally deposited on January 17, 2012, at the Patent Microbial Collection Center of the Technical Base for Product Evaluation (Room 122, 2-5-8 Kazusa-Kamazu, Kisarazu City, Chiba Prefecture, Japan 292-0818, Japan) based on the Budapest Treaty.

[0047] Bacteria assigned the accession number FERM BP-10742, bacteria assigned the accession number FERM BP-10744, bacteria assigned the accession number FERM BP-10745, and bacteria assigned the accession number FERM BP-10746 were internationally deposited on December 1, 2006, at the Patent Biology Collection Center of the National Institute of Advanced Industrial Science and Technology (now the Patent Biology Collection Center of the Product Evaluation Technology Base Organization, Room 120, 2-5-8 Kazusa-Kamazu, Kisarazu City, Chiba Prefecture, Japan 292-0818, Japan) based on the Budapest Treaty.

[0048] The bacteria, which was assigned the accession number FERM BP-10757, was internationally deposited on January 10, 2007, at the Patent Biology Collection Center of the National Institute of Advanced Industrial Science and Technology (now the Patent Biology Collection Center of the Product Evaluation Technology Base Organization, Room 120, 2-5-8 Kazusa-Kamazu, Kisarazu City, Chiba Prefecture, Japan 292-0818, Japan) based on the Budapest Treaty.

[0049] One type of Lactococcus bacteria can be used, or two or more types can be used in combination.

[0050] In this invention, it is particularly preferred to use one or both of NITE BP-02621 and FERM BP-11175 as Bifidobacterium, and NITE BP-1204 as Lactococcus.

[0051] Iron compounds can be any known iron compounds that can be added to food. Iron compounds containing non-heme iron are preferred.

[0052] Iron compounds containing non-heme iron can be well-known iron compounds. Examples include ferric pyrophosphate, ferrous citrate, and ferric ammonium citrate.

[0053] Iron compounds containing non-heme iron can be in the form of suitable salts, such as sodium ferrous citrate, which can be ferrous citrate.

[0054] One type of iron-containing compound can be used, or two or more types can be used in combination.

[0055] The iron content per 100g of fermented food is preferably 0.3mg or more, more preferably 0.6mg or more, even more preferably 0.9mg or more, even more preferably 2.5mg or more, even more preferably 5.0mg or more, and even more preferably 10.0mg or more. When the iron content is above the lower limit mentioned above, the effect of improving the survival of Bifidobacteria is excellent. There is no particular limitation on the upper limit, but from the perspective of flavor, it is preferably below 25mg, more preferably below 20mg, and even more preferably below 15mg.

[0056] In this specification, the iron content is determined by ICP (inductively coupled plasma) spectroscopy. The iron content of fermented foods can be calculated based on the iron content and amount of the raw materials used in the manufacture of the fermented food.

[0057] The iron content per 100g of fermented food can be 0.3mg or more but less than 25mg, 0.3mg or more but less than 20mg, 0.3mg or more but less than 15mg, 0.6mg or more but less than 25mg, 0.6mg or more but less than 20mg, 0.6mg or more but less than 15mg, 0.9mg or more but less than 25mg, 0.9mg or more but less than 20mg, 0.9mg or more but less than 15mg, 2.5mg or more but less than 25mg, 2.5mg or more but less than 20mg, 2.5mg or more but less than 15mg, 5.0mg or more but less than 25mg, 5.0mg or more but less than 15mg, 10.0mg or more but less than 25mg, 10.0mg or more but less than 20mg, or 10.0mg or more but less than 15mg.

[0058] The optimal content of live Bifidobacteria per 100g of fermented food is 1×10⁻⁶.8 CFU or higher, preferably 1×10 9 CFU or higher, further preferably 1×10 10 cfu or above.

[0059] In this specification, the viable count of Bifidobacteria is a value obtained by the determination method described in the examples described later.

[0060] The live Bifidobacteria content per 100g of fermented food can be 1×10⁻⁶. 8 CFU or higher and 1×10 13 CFU or less, 1×10 8 CFU or higher and 1×10 12 CFU or less, 1×10 8 CFU or higher and 5×10 11 CFU or less, 1×10 9 CFU or higher and 1×10 13 CFU or less, 1×10 9 CFU or higher and 1×10 12 CFU or less, 1×10 9 CFU or higher and 5×10 11 CFU or less, 1×10 10 CFU or higher and 1×10 13 CFU or less, 1×10 10 CFU or higher and 1×10 12 CFU or less, or 1×10 10 CFU or higher and 5×10 11 Below CFU level.

[0061] Fermented foods contain moisture. The solid content of fermented foods is preferably 3% or more and 28% or less by mass, more preferably 5% or more and 26% or less by mass, and even more preferably 8% or more and 23% or less by mass.

[0062] When the fermented food is fermented milk, the non-fat milk solids content relative to the total mass of the fermented food is preferably 2.9% by mass or more and 20% by mass or less, more preferably 4.9% by mass or more and 18% by mass or less, and even more preferably 7.9% by mass or more and 15% by mass or less.

[0063] In this specification, the content of solid components is calculated using the formula: "Solid component (unit: mass%) = 100 - Moisture (unit: mass%)". The moisture content is determined by atmospheric pressure heating drying method.

[0064] Specifically, the moisture content is calculated by measuring the weight loss when the sample is dried in a thermostat at 99°C for 4 hours using the following formula.

[0065] Moisture content (in mass%) = (Mass of sample before drying (in g) - Mass of sample after drying (in g)) / Mass of sample before drying (in g) × 100

[0066] Nonfat milk solids content is the value obtained by subtracting the fat (also known as milk fat) content from the solids content derived from milk (also known as milk solids content).

[0067] Fat content was measured using the Rose-Gottlieb method. Specifically, 3g of sample was collected in a Mojonnier tube, and 7ml of water, 1 drop of phenolphthalein, and 2ml of ammonia were added, followed by gentle shaking. Then, 10ml of ethanol, 25ml of diethyl ether, and 25ml of petroleum ether were added, stoppering the tube after each addition and shaking 2-3 times. After centrifugation, the solvent layer was transferred to an evaporating dish to allow the solvent to evaporate. The residue was fat. The mass of this residue was weighed as the fat content. The ratio of the fat mass to the 3g sample was determined as the fat content (unit: mass%).

[0068] Fermented foods contain fermented substances.

[0069] In the case of fermented milk, the fermented food includes a fermented product obtained by fermenting a raw material composition containing milk raw materials using fermenting bacteria. The milk raw materials can be those known in the manufacture of fermented milk. Examples include raw milk, cream, skim milk concentrate, skim milk powder, and milk protein concentrate. One type of milk raw material can be used, or two or more can be used in combination.

[0070] In the case of fermented foods that are not fermented milk, fermented foods include fermented products obtained by fermenting a combination of raw materials containing a fermentation substrate other than milk raw materials using fermenting bacteria. Examples of fermentation substrates other than milk raw materials include plant-based milk. Plant-based milk refers to milky foods derived from plant materials. Examples of plant-based milk include soy milk, almond milk, rice milk, coconut milk, and oat milk. One type of plant-based milk may be used, or two or more may be used in combination.

[0071] The raw material composition may further include sugars, vegetable fats, stabilizers, flavorings, pH adjusters, fruit juices / pulp, sweeteners, and other ingredients known in fermented foods.

[0072] Examples of the aforementioned stabilizers include agar, gelatin, and pectin. Examples of the aforementioned sweeteners include sucralose.

[0073] Fermenting bacteria include Bifidobacteria and Lactococcus. Other fermenting bacteria may also be included. Examples of other fermenting bacteria include Streptococcus thermophilus and Lactobacillus bulgaricus. One or more other fermenting bacteria may be used. Well-known lactic acid bacteria starter cultures can be used as other fermenting bacteria.

[0074] The pH of fermented food at 10°C is preferably 3.7 or higher and 5.0 or lower, more preferably 4.0 or higher and 4.7 or lower.

[0075] During the preservation of fermented foods, the viable count of Bifidobacteria decreases. As shown in the examples described later, according to the present invention, fermented foods with excellent Bifidobacterium viability can be obtained.

[0076] For example, if the storage period from the date of manufacture to the day following the manufacturing date (i.e., day 0) is set to 1 day, the viable Bifidobacteria content per 100g of fermented food can be maintained at 1×10⁻⁶. 9 Fermented foods with a fermentation period of 7 days or more, preferably 11 days or more, more preferably 14 days or more, and even more preferably 21 days or more.

[0077] More preferably, the viable bifidobacteria content per 100g of fermented food is maintained at 3.5×10⁻⁶. 9 Fermented foods with a fermentation period of 7 days or more, preferably 11 days or more, more preferably 14 days or more, and even more preferably 21 days or more.

[0078] There is no particular limit to the viable Bifidobacteria content at the beginning of the storage of fermented foods. For example, the viable Bifidobacteria content per 100g of fermented food at the beginning of storage can be 1×10⁻⁶. 13 For levels below CFU, the value can be 1×10. 12 Below CFU, it can also be 5×10 11 Below CFU level.

[0079] In the fermented food of the present invention, any ingredients may be appropriately used without impairing the effects of the present invention. Examples of such ingredients include, for instance, animal or vegetable oils, dietary fiber, emulsifiers, stabilizers, thickeners, sugars, sugar alcohols, polysaccharides, pH adjusters, fatty acid esters, flavoring and odor-correcting agents, flavorings, sweeteners, colorings, and excipients.

[0080] The fermented food of the present invention can be manufactured by a fermentation process having a fermentation step of fermenting a raw material composition containing Bifidobacterium, Lactococcus bacteria and iron-containing compounds to obtain a fermented product.

[0081] The components of the feedstock composition are preferably designed according to the desired composition of the fermented product. The total mass of the feedstock composition is the same as the total mass of the fermented product at the end of the fermentation process.

[0082] In the raw material composition, the "iron / bifidobacteria" ratio, which represents the ratio of iron content (mg / 100g) to the viable bifidobacteria content (cfu / 100g), is preferably 1.0 × 10⁻⁶. -12 Above and 1.0×10 -6 Hereinafter, 1.0 × 10 is preferred. -11 Above and 1.0×10 -7 Hereinafter, 1.0 × 10 is further preferred. -10 Above and 1.0×10 -8 the following.

[0083] In the raw material composition, the "Lactococcus spp. / Bifidobacterium" ratio, which represents the ratio of the content of Lactococcus spp. (in CFU / 100g) to the content of viable Bifidobacterium spp. (in CFU / 100g), is preferably 1.0 × 10⁻⁶. -2 More than or equal to 10, preferably 5.0 × 10 -2 More than or equal to 5, and more preferably 3.0 × 10 -1 Above and below 1.

[0084] Preferably, the iron content per 100g of fermented food is the same as the iron content per 100g of the raw material composition. Without adding iron after the fermentation process, the iron content per 100g of fermented food is the same as the iron content per 100g of the raw material composition.

[0085] In the preparation process of the raw material composition, raw materials other than fermentation bacteria are mixed, preferably homogenized, and then sterilized by heating before adding fermentation bacteria (also known as inoculation) to produce the raw material composition.

[0086] Homogenization and heat sterilization can be carried out using conventional methods.

[0087] In the fermentation process, the raw material composition containing fermenting bacteria is fermented at a specified fermentation temperature. The fermentation temperature is preferably 35°C or higher and 43°C or lower, more preferably 37°C or higher and 41°C or lower.

[0088] As fermentation proceeds, the pH of the raw material composition decreases. After reaching the predetermined endpoint pH, the mixture is cooled to obtain the fermented product. The endpoint pH is preferably 4.0 or higher and 5.0 or lower, more preferably 4.2 or higher and 4.8 or lower. The cooling temperature is preferably 3°C or higher and 15°C or lower, more preferably 5°C or higher and 10°C or lower.

[0089] The fermentation process can be carried out using well-known methods.

[0090] The fermented product obtained after the fermentation process can be used directly as a fermented food, or it can be further processed to become a fermented food.

[0091] There are no particular restrictions on the form of fermented food products.

[0092] For example, in the manufacture of fermented milk, a static fermented milk is obtained by fermenting the raw material composition in a product container such as a cup.

[0093] Alternatively, the raw material composition can be fermented in a tank, and the resulting fermented product (also known as curd) can be stirred, crushed, and filled into a product container to obtain stirred fermented milk or beverage-type fermented milk.

[0094] Especially in the production of beverage-type fermented milk, it is preferable to smooth the fermented material (also known as curd). Smoothing refers to the process of breaking down the fermented material to make it smooth. Breaking methods known in the production of fermented milk can be used. Specific examples include homogenizers, back pressure valves, filters, and pumps.

[0095] According to the present invention, it is possible to improve the survival rate of Bifidobacteria in fermented products obtained by fermenting a raw material composition containing live Bifidobacteria.

[0096] As shown in the examples described later, when a raw material composition containing Bifidobacterium, Lactococcus, and an iron-containing compound is fermented, the viability of Bifidobacterium in the fermented product obtained by fermentation is improved compared to a case where the raw material composition contains Bifidobacterium but does not contain one or both of Lactococcus and an iron-containing compound.

[0097] The method for improving the viability of Bifidobacteria of the present invention is a method for improving the viability of Bifidobacteria in a ferment obtained by fermenting a raw material composition containing Bifidobacteria, comprising a step of fermenting a raw material composition containing Bifidobacteria, Lactococcus bacteria and an iron-containing compound.

[0098] In this invention, improved viability refers to a slower decline in the number of viable Bifidobacteria during the preservation of fermented foods. When fermented foods that have undergone the same preservation period are compared, those with improved viability have a higher number of viable Bifidobacteria.

[0099] For example, the viable Bifidobacteria content at the start of storage for every 100g of fermented food exceeds 1×10⁻⁶. 12 CFU and is 1×10 13 Below CFU, the live Bifidobacteria content in 100g of fermented food remains at 1×10⁻⁶. 9The duration of CFU or above can be 7 days or more, 11 days or more, 14 days or more, or 21 days or more.

[0100] The viable Bifidobacteria content at the beginning of storage for every 100g of fermented food exceeds 1×10⁻⁶. 12 CFU and is 1×10 13 Below CFU, the viable Bifidobacteria content in fermented food remains at 3.5 × 10⁻⁶ per 100g. 9 The duration of CFU or above can be 7 days or more, 11 days or more, 14 days or more, or 21 days or more.

[0101] The viable Bifidobacteria content at the beginning of storage for every 100g of fermented food exceeds 5×10⁻⁶. 11 CFU and is 1×10 12 Below CFU, the live Bifidobacteria content in 100g of fermented food remains at 1×10⁻⁶. 9 The duration of CFU or above can be 7 days or more, 11 days or more, 14 days or more, or 21 days or more.

[0102] The viable Bifidobacteria content at the beginning of storage for every 100g of fermented food exceeds 5×10⁻⁶. 11 CFU and is 1×10 12 Below CFU, the viable Bifidobacteria content in fermented food remains at 3.5 × 10⁻⁶ per 100g. 9 The duration of CFU or above can be 7 days or more, 11 days or more, 14 days or more, or 21 days or more.

[0103] The viable Bifidobacteria content at the beginning of storage for every 100g of fermented food is 1×10⁻⁶. 10 CFU or higher and 5×10 11 Below CFU, the live Bifidobacteria content in 100g of fermented food remains at 1×10⁻⁶. 9 The duration of CFU or above can be 7 days or more, 11 days or more, 14 days or more, or 21 days or more.

[0104] The viable Bifidobacteria content at the beginning of storage for every 100g of fermented food is 1×10⁻⁶. 10 CFU or higher and 5×10 11 Below CFU, the viable Bifidobacteria content in fermented food remains at 3.5 × 10⁻⁶ per 100g. 9 The duration of CFU or above can be 7 days or more, 11 days or more, 14 days or more, or 21 days or more.

[0105] The present invention has the following aspects.

[0106] <1> A method for manufacturing fermented milk includes the following steps: heating and sterilizing a mixture comprising one or more iron-containing compounds selected from the group consisting of ferric pyrophosphate, ferrous citrate and ferric ammonium citrate, milk raw materials and water; adding fermentation bacteria comprising Bifidobacterium and Lactococcus to obtain a raw material composition; fermenting the raw material composition until the pH reaches 4.2 or higher and 4.8 or lower; and then cooling to obtain fermented milk.

[0107] Relative to the total mass of the aforementioned raw material composition, the solid content is 8% by mass or more and 23% by mass, and the non-fat emulsion solid content is 7.9% by mass or more and 15% by mass or less.

[0108] The iron content per 100g of the aforementioned raw material composition is 0.3mg or more and 15mg or less.

[0109] In the aforementioned raw material composition, the "iron / bifidobacteria" ratio, which represents the ratio of iron content (unit: mg / 100g) to the viable bifidobacteria content (unit: CFU / 100g), is 1.0 × 10⁻⁶. -10 Above and 1.0×10 -8 The following, where "Lactococcus spp. / Bifidobacterium" represents the ratio of the aforementioned Lactococcus spp. content (in CFU / 100g) to the aforementioned Bifidobacterium viable content (in CFU / 100g), is 3.0 × 10⁻⁶. -1 Above and below 1,

[0110] The viable Bifidobacteria content in 100g of the aforementioned freshly cooled fermented milk was 1×10⁻⁶. 10 CFU or higher and 5×10 11 Below CFU level.

[0111] <2> According to the foregoing <1> The method for manufacturing fermented milk, wherein the aforementioned raw material composition contains no iron except for the aforementioned iron-containing compound, and no iron is added after obtaining fermented milk through the aforementioned cooling process.

[0112] <3> According to the foregoing <1> or <2> In the method for manufacturing fermented milk, the aforementioned Bifidobacterium is one or both of Bifidobacterium longum subsp. longum and Bifidobacterium breve, and the aforementioned Lactococcus bacteria is Lactococcus lactis subsp. lactis.

[0113] <4> According to the foregoing <1> or <2> In the method for manufacturing fermented milk, the aforementioned Bifidobacterium is one or both of NITE BP-02621 and FERM BP-11175, and the aforementioned Lactococcus bacteria is NITE BP-1204.

[0114] <5> According to the foregoing <1> ~ <3> The method for manufacturing fermented milk according to any one of the following methods, wherein the aforementioned fermenting bacteria further comprises lactic acid bacteria starter.

[0115] <6> According to the foregoing <5> In the method for manufacturing fermented milk, the aforementioned lactic acid bacteria starter is a mixed culture of Streptococcus thermophilus and Lactobacillus bulgaricus.

[0116] <7> A method through the aforementioned <1> ~ <6> Fermented milk obtained by any one of the manufacturing methods described above.

[0117] <8> A fermented milk, which is produced by the aforementioned <1> ~ <6> The fermented milk obtained by any one of the manufacturing methods, when the storage period from the date of manufacture to the day following the manufacturing date (day 0) is set to 1 day, has a pH of 4.0 or higher and 4.7 or lower at 10°C after 7 days of storage, and the viable count of the aforementioned Bifidobacterium per 100g of fermented milk is 3.5 × 10⁻⁶. 9 cfu or above.

[0118] <9> A fermented milk, which is produced by the aforementioned <1> ~ <6> The fermented milk obtained by any one of the manufacturing methods, when the storage period from the date of manufacture to the day following the manufacturing date (day 0) is set to 1 day, has a pH of 4.0 or higher and 4.7 or lower at 10°C after 11 days of storage, and the viable count of the aforementioned Bifidobacteria per 100g of fermented milk is 3.5 × 10⁻⁶. 9 cfu or above.

[0119] <10> A fermented milk, which is produced by the aforementioned <1> ~ <5> The fermented milk obtained by any one of the manufacturing methods, when the storage period from the date of manufacture to the day following the manufacturing date (day 0) is set to 1 day, has a pH of 4.0 or higher and 4.7 or lower at 10°C after being stored for 14 days, and the viable count of the aforementioned Bifidobacteria per 100g of fermented milk is 3.5 × 10⁻⁶. 9 cfu or above.

[0120] <11> A fermented milk, which is produced by the aforementioned <1> ~ <6> The fermented milk obtained by any one of the manufacturing methods, when the storage period from the date of manufacture to the day following the manufacturing date (day 0) is set to 1 day, has a pH of 4.0 or higher and 4.7 or lower at 10°C after 21 days of storage, and the viable count of the aforementioned Bifidobacterium per 100g of fermented milk is 3.5 × 10⁻⁶. 9 cfu or above.

[0121] <12> A fermented milk, which is produced by the aforementioned <1> ~ <6> The fermented milk obtained by any one of the manufacturing methods, when the storage period from the date of manufacture to the day following the manufacturing date (day 0) is set to 1 day, has a pH of 4.0 or higher and 4.7 or lower at 10°C after 22 days of storage, and the viable count of the aforementioned Bifidobacterium per 100g of fermented milk is 3.5 × 10⁻⁶. 9 cfu or above.

[0122] <13> A fermented milk, which is produced by the aforementioned <1> ~ <6> The fermented milk obtained by any one of the manufacturing methods, when the storage period from the date of manufacture to the day following the manufacturing date (day 0) is set to 1 day, has a pH of 4.0 or higher and 4.7 or lower at 10°C after 23 days of storage, and the viable count of the aforementioned Bifidobacterium per 100g of fermented milk is 3.5 × 10⁻⁶. 9 cfu or above.

[0123] Example

[0124] The present invention will be further described in detail below using examples, but the present invention is not limited to these examples.

[0125] <Determination Method>

[0126] The viable count of Bifidobacteria was determined using TOS propionic acid agar medium (manufactured by Yakult Pharmaceuticals). Specifically, the following steps were followed.

[0127] Dissolve / suspend 1g of sample (fermentation product) in 9mL of 0.85% sterile physiological saline. After the suspension is diluted in stages, it is anaerobically cultured on TOS medium (trans-oligosaccharide propionic acid agar medium, manufactured by Yakult Pharmaceutical Co., Ltd.) at 37°C for 72 hours, and the colony count is performed.

[0128] The iron content was determined by ICP (inductively coupled plasma) spectroscopy.

[0129] The viable counts of "Lactococcus spp. / Bifidobacterium" in the raw material composition were determined by the following method, and the ratio of the viable count of Lactococcus spp. to the viable count of Bifidobacterium was calculated.

[0130] <Lactococcus>

[0131] Dissolve / suspend 1g of the raw material composition in 9mL of 0.85% sterile physiological saline, and then dilute the suspension in stages. Incubate the diluted solution aerobically at 37°C for 72 hours using BCP plate counting agar (manufactured by Eiken Chemical Co., Ltd.), and count the colonies. Multiply the colony count by the dilution factor to determine the viable cell count.

[0132] Bifidobacteria

[0133] Dissolve / suspend 1g of the raw material composition in 9mL of 0.85% sterile physiological saline, and then dilute the suspension in stages. Incubate the diluted solution anaerobically at 37°C for 72 hours on TOS medium (trans-oligosaccharide propionic acid agar, Yakult Pharmaceutical Co., Ltd.), and count the colonies. Multiply the colony count by the dilution factor to determine the viable count.

[0134] <Ingredients Used>

[0135] • Skim milk powder: manufactured by Morinaga Milk Industry Co., Ltd., protein 34.0% by mass, lipid 1.0% by mass, non-fat milk solids 95.2%, calcium content 1.1%.

[0136] • Sugar: Mitsui Sugar's product name "Sugar".

[0137] • Iron preparation (1): SunActive Fe-12A, manufactured by Taiyo Chemical Co., Ltd., is a preparation containing iron pyrophosphate with an iron content of 12 mg / g.

[0138] • Iron preparation (2): San-eigen FFI Co., Ltd., product name "FEbase No.36833", a preparation containing iron pyrophosphate, iron content 25mg / g.

[0139] • Iron preparations (3): Sanferol, a preparation containing sodium ferrous citrate, manufactured by Mitsubishi Chemical Corporation, with an iron content of 105 mg / g.

[0140] • Iron preparations (4): "Ferric ammonium citrate" manufactured by Showa Chemical Co., Ltd., a preparation containing ferric ammonium citrate, with an iron content of 171 mg / g.

[0141] • Bifidobacterium (1): Culture of Bifidobacterium longum BB536 (NITE BP-02621 strain) produced by Morinaga Dairy Co., Ltd.

[0142] • Bifidobacterium (2): Culture of Bifidobacterium breve MCC1274 (FERM BP-11175 strain) produced by Morinaga Dairy Co., Ltd.

[0143] • Lactococcus bacteria (1): Culture of Lactococcus lactis (NITEBP-1204 strain) produced by Morinaga Dairy Co., Ltd.

[0144] • Lactic acid bacteria starter (1): A mixed culture of commercially available Streptococcus thermophilus and Lactobacillus bulgaricus.

[0145] <Example 1~27>

[0146] Examples 1, 6-7, 9-10, 12-14, 16-23, and 25-27 are examples, and examples 2-4, 5, 8, 11, 15, and 24 are comparative examples.

[0147] Prepare the raw material composition according to the formulations shown in Tables 1-5.

[0148] Specifically, using a mixer, skim milk powder, sugar, iron supplements, and room temperature water (i.e., dissolving water) are mixed and heated to 70°C to dissolve. Next, homogenization is performed using a homogenizer at 15 MPa pressure, followed by heat sterilization at 90°C for 10 minutes, and then cooled to 38°C. Then, Bifidobacterium, Lactococcus, and lactic acid bacteria starter are added to obtain the raw material composition. In the raw material composition, the ratio of viable Lactococcus bacteria (cfu / 100g) to viable Bifidobacterium bacteria (cfu / 100g), expressed as "Lactococcus bacteria / Bifidobacterium," is always 0.4.

[0149] The non-fat milk solids content of the raw material composition is calculated from the non-fat milk solids content indicated in the raw materials and the proportions of each raw material. Alternatively, it can be determined by subtracting the fat content obtained by the above-described fat determination method from the milk solids content. The milk solids content is determined from the amount of milk solids in the raw materials, or by subtracting the non-milk solids from the solids content.

[0150] Next, the raw material composition is filled into a cup and kept at 38°C to ferment until the pH reaches 4.7. Then, it is cooled to 10°C to obtain fermented milk.

[0151] After storing the obtained fermented milk in a refrigerator at 10°C for the specified period, the number of Bifidobacteria was determined using the method described above. The storage period is shown in the table. For example, the day of manufacture is day 0, and the day following the manufacture date is day 1. In each case, the viable Bifidobacteria count at the start of storage was confirmed to be 1 × 10⁻⁶. 10 CFU or higher and 5×10 11 Below CFU. The test results are shown in the respective tables and... Figs. 1-6 In the chart. Figs. 1-6 In the figure, the horizontal axis represents the storage period (unit: days), and the vertical axis represents the number of Bifidobacteria (unit: cfu / 100g).

[0152] In each case, it was confirmed that the pH (measurement temperature: 10°C) remained above 4.7 and below 4.0 during the storage period shown in the table.

[0153] [Table 1]

[0154]

[0155] [Table 2]

[0156]

[0157] [Table 3]

[0158]

[0159] [Table 4]

[0160]

[0161] [Table 5]

[0162]

[0163] As shown in Table 1, the fermented food of Example 1, which contains Bifidobacterium, Lactococcus, and iron compounds, had a higher number of Bifidobacterium and improved viability after preservation compared to Examples 2-4, which do not contain one or both of Lactococcus and iron compounds.

[0164] In particular, when comparing Examples 3 and 4, the number of Bifidobacteria was significantly reduced in both Examples 3 (containing iron compounds) and Examples 4 (not containing iron compounds) after 11 days of storage when there were no Lactococcus bacteria.

[0165] On the other hand, when comparing Examples 1 and 2, when containing Lactococcus bacteria, the number of Bifidobacteria in Example 1, which contained iron compounds, was significantly increased after 18 days of storage compared to Example 2, which did not contain iron compounds.

[0166] Therefore, it is believed that the survival rate of Bifidobacteria is further improved through the synergistic effect of Lactococcus bacteria and iron-containing compounds.

[0167] As shown in Table 2, in Examples 5-7 using Bifidobacterium (1) and Examples 8-10 using Bifidobacterium (2), compared with Examples 5 or 8 which contained Lactococcus bacteria but did not contain iron compounds, Examples 6, 7 or Examples 9, 10 which contained Lactococcus bacteria and iron compounds had a higher number of preserved Bifidobacterium bacteria and improved viability. It should be noted that in Examples 6 and 7 using Bifidobacterium (1) and Examples 9 and 10 using Bifidobacterium (2), the side with higher iron content had a higher number of preserved Bifidobacterium bacteria and improved viability.

[0168] As shown in Table 3, compared with Example 11, which contained Lactococcus bacteria but did not contain iron compounds, Example 12, which contained Lactococcus bacteria and iron compounds (2), Example 13, which contained iron compounds (3), and Example 14, which contained iron compounds (4), all had a higher number of Bifidobacteria after preservation and improved viability.

[0169] As shown in Table 4, compared with Example 15, which contained Lactococcus bacteria but did not contain iron compounds, Examples 16-19, which contained Lactococcus bacteria and had an iron content of 0.3-5 mg / 100g in iron preparation (2), and Examples 20-23, which had an iron content of 0.3-5 mg / 100g in iron preparation (3), all showed higher numbers of Bifidobacteria after preservation, and their viability was improved. It should be noted that in Examples 16-19 using iron preparation (2) and Examples 20-23 using iron preparation (3), the one with higher iron content consistently showed higher numbers of Bifidobacteria after preservation, and their viability was improved.

[0170] As shown in Table 5, compared with Example 24, which contained Lactococcus bacteria but did not contain iron compounds, Examples 25-27, which contained Lactococcus bacteria and iron compounds with an iron content of 0.9-10 mg / 100g, all showed higher numbers of Bifidobacteria after preservation, and their viability was improved. It should be noted that the higher iron content resulted in higher numbers of Bifidobacteria and improved viability after preservation.

Claims

1. A fermented food containing Bifidobacterium, Lactococcus bacteria and iron-containing compounds.

2. The fermented food according to claim 1, wherein, The iron content of the fermented food is 0.3 mg or more per 100g.

3. The fermented food according to claim 1, wherein, The iron-containing compound contains non-heme iron.

4. The fermented food according to claim 3, wherein, The iron-containing compound comprises one or more selected from the group consisting of ferric pyrophosphate, ferrous citrate, and ferric ammonium citrate.

5. The fermented food according to claim 1, wherein, The viable count of Bifidobacteria in each 100g of the fermented food is 1×10⁻⁶. 8 cfu or above.

6. The fermented food according to claim 1, wherein, The Bifidobacteria include one or more species selected from the group consisting of Bifidobacterium longum and Bifidobacterium breve.

7. The fermented food according to claim 1, wherein, The Lactococcus genus bacteria includes Lactococcus lactis.

8. The fermented food according to claim 1, wherein, The fermented food is fermented milk.

9. A method for manufacturing a fermented food, comprising a step of fermenting a raw material composition containing Bifidobacterium, Lactococcus bacteria and an iron-containing compound.

10. A method for improving the viability of Bifidobacteria, comprising a method for improving the viability of Bifidobacteria in a fermentation product obtained by fermenting a raw material composition containing Bifidobacteria. The method involves fermenting a raw material composition containing Bifidobacterium, Lactococcus bacteria, and iron-containing compounds.

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