JP2023014396A - Bifidobacteria survival-improving composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the survival of bifidobacteria, particularly the survival during cold storage, without the need for externally adding non-milk components, and without affecting the flavor or physical properties of food.

SOLUTION: The problem is solved by a composition for improving the survival of bifidobacteria containing decomposed milk protein.

SELECTED DRAWING: None

COPYRIGHT: (C)2023,JPO&INPIT

Description

TECHNICAL FIELD The present invention relates to a composition for improving viability of bifidobacteria.

Beneficial microorganisms that can have beneficial effects on the host, such as improving the flora in the gastrointestinal tract, include:
It is called probiotic bacteria and attracts attention. Bifidobacteria are such useful microorganisms. However, bifidobacteria with such functionality have been considered to have poor viability and survival in milk. So far, various solutions have been disclosed for culturing probiotic bacteria in milk to improve their viability.
Patent Document 1 discloses an agent for improving the survival of lactic acid bacteria and/or bifidobacteria that can improve the survival of probiotic lactic acid bacteria and bifidobacteria in an acidic (low pH) environment, and an agent using the same The object is to provide a food composition and a method for producing the same, and as a means for solving the problem, an agent for improving the survival of lactic acid bacteria and/or bifidobacteria containing an amino acid as an active ingredient is disclosed.
Patent document 2 aims to provide a novel substance that promotes the growth of bifidobacteria and lactic acid bacteria. there is

However, the technique described in Patent Document 1 requires the addition of various amino acids to the yogurt mix, and these amino acids are highly likely to affect the flavor of the final product. Also in Patent Document 2, it is necessary to add an egg white hydrolyzate to the culture medium. Even in this case, the flavor may be affected, and it cannot be denied that there is a possibility that allergy problems will occur and those who eat it will be restricted.

Patent No. 6088821 Japanese Patent Application Laid-Open No. 2000-93166

An object of the present invention is to provide a novel composition for improving viability of bifidobacteria and a method for improving viability of bifidobacteria.

In order to solve the above problems, the present invention includes the following configurations.
(1) A composition for improving the viability of bifidobacteria containing a milk protein hydrolyzate,
(2) The composition for improving the viability of bifidobacteria according to (1), which is a medium for culturing bifidobacteria,
(3) the peptide concentration in the composition is 1.8 mg/L or more, (1) or (2)
) for improving the viability of bifidobacteria,
(4) the total concentration of L-amino acids in the composition is 4.6 mM or more, (1)-
The composition for improving the viability of bifidobacteria according to any one of (3),
(5) The composition for improving the viability of bifidobacteria according to any one of (1) to (4), wherein the improvement in viability is suppression of the decrease in the number of bifidobacteria at 10°C or lower.
(6) A method for improving the viability of bifidobacteria, which comprises culturing or fermenting bifidobacteria in a culture medium containing 1.8 mg/L or more of milk protein-derived peptides in terms of medium,
(7) The method for improving viability of Bifidobacterium according to (6), wherein the L-amino acid concentration in the culture medium is 4.6 mM or more.
(8) the Bifidobacterium is Bifidobacterium longum, (6) or (7)
The method for improving the viability of bifidobacteria according to
(9) The method for improving the viability of Bifidobacterium according to any one of (6) to (8), further comprising producing a total of 0.2 mM or more of phenylalanine and serine in the culture medium, and ( 10) The method for improving viability of bifidobacteria according to any one of (6) to (9), wherein the improvement of viability is suppression of decrease in the number of bifidobacteria at 10°C or lower.

The present invention provides a novel composition for improving viability of bifidobacteria and a method for improving viability of bifidobacteria. According to the present invention, there is no need to add anything other than milk components from the outside, and the survival of bifidobacteria, especially during refrigerated storage, is improved without affecting the flavor and physical properties of the food. can be made

1 is a graph showing the relative ratio of the number of Bifidobacterium longum reaching bacteria in each of 10 protease-treated media and a control medium (no protease treatment). 4 is a graph showing peptide concentrations in each of four types of protease-treated media and a control medium (no protease treatment). 4 is a graph showing L-amino acid concentrations in each of four protease-treated media and a control medium (no protease treatment). Five types of bulk starters were prepared using four types of protease-treated media and a control medium (no protease treatment), and the fermented milk prepared using the five types of bulk starters was refrigerated. It is the graph which showed the Bifidobacterium longum survival rate.

The present invention is described in detail below. In this specification, percentages are by weight even when not specified.

[1] Composition for improving viability of bifidobacteria (improving viability)
In the present invention, "survival improvement" means suppressing the death of bifidobacteria and maintaining the number of surviving bacteria (decrease suppression), as well as promoting the growth of bacteria (proliferation promotion). Contain meaning.
In addition, in the present invention, "improving survival" includes suppressing a decrease in the number of bacterial cells when stored for a certain period of time under specific conditions, for example, under storage conditions of 10°C or less.

(Composition for Improving Viability of Bifidobacterium)
The composition for improving the viability of Bifidobacterium of the present invention contains a milk protein hydrolyzate obtained by treating milk protein with a proteolytic enzyme. This milk protein hydrolyzate preferably contains peptides with a molecular weight of 10,000 or less and L-amino acids.
This peptide may be any milk protein-derived peptide, but may be one or more selected from casein-derived peptides, β-lactoglobulin-derived peptides, and α-lactalbumin-derived peptides. Preferably, peptides derived from casein,
It is more preferable to adjust the ratio of peptides other than casein to about 75:25 to 85:15.
The L-amino acid concentration in the composition for improving the viability of Bifidobacterium of the present invention is preferably 4.6 mM or higher, more preferably 4.65 mM or higher, and 4.7 mM or higher. is more preferable.

(milk protein)
Any protein contained in animal milk of cows, buffaloes, sheep, goats, horses, etc. can be used as the milk protein used in the production of the composition for improving the viability of bifidobacteria of the present invention. . Therefore, in the production of the composition for improving the viability of Bifidobacterium of the present invention, any milk material containing the above protein can be used, and milk protein concentrate (Milk Protein Isolate, Milk Protein Conce
ntrate) and whey protein concentrate (Whey Protein Isolate,
Whey Protein Concentrate), as well as raw milk containing milk protein, milk, partially skimmed milk, skim milk, whole skim milk, skim milk powder, whole milk powder, concentrated milk, skimmed concentrated milk, adjustment Milk powder, milk protein, etc. can be used,
These materials can be used alone or in combination of two or more.

(Decomposition of milk protein)
The composition for improving the viability of bifidobacteria of the present invention is obtained by preparing an aqueous solution containing about 1 to 10% of the above-described milk protein, adding a proteolytic enzyme described later, and decomposing the milk protein. can be done. Proteolysis is preferably carried out so that the molecular weight of the peptide is 10,000 or less and the total amount of phenylalanine and serine produced by proteolysis is 0.2 mM or more. Further, proteolysis is more preferably carried out so that the total amount of phenylalanine and serine produced by proteolysis is 0.2 to 0.5 mM.
Conditions such as concentration of milk protein at this time, enzyme to be used, reaction temperature, reaction time, deactivation, etc.
The molecular weight of the peptide can be adjusted to 10,000 or less and the total amount of phenylalanine and serine generated by proteolysis to 0.2 mM or more, depending on the milk protein, enzymes, equipment, etc. used.
The resulting peptide-containing solution can be used as it is as a composition for improving the viability of bifidobacteria, but it can also be dried and used as a powder. Alternatively, peptides purified by separation, fractionation, or the like can also be used.

As the proteolytic enzyme, any proteolytic enzyme derived from microorganisms or the like that can be used in foods can be used without restriction, and there are no particular restrictions on the endo-type protease or exo-type protease, but as described above, the molecular weight is 10,000 or less. and the total amount of phenylalanine and serine generated by proteolysis is preferably 0.2 mM or more. or exo-type protease derived from Aspergillus.oryzae (rice koji mold) is more preferable, and a mixture of endo-type protease and exo-type protease derived from Aspergillus.oryzae (rice koji mold), or Aspergillus.oryz
Among the exo-type proteases derived from ae (rice koji mold), the optimum pH is around 7 and the optimum temperature is 50~
A temperature of about 70° C. is more preferable. More preferable enzymes include Denazym AP (Nagase ChemteX Corporation) and Proteax (Amano Enzyme Corporation).
Other enzymes that can be used include Sumiteam LP50D (Shinnihon Chemical Industry Co., Ltd.), Sumiteam FL-G (Shinnihon Chemical Industry Co., Ltd.), Sumiteam LPL-G (Shinnihon Chemical Industry Co., Ltd.),
Sumiteam DPP-G (Shinnihon Chemical Industry Co., Ltd.), Sumiteam P (Shinnihon Chemical Industry Co., Ltd.)
, Protease A "Amano" SD (Amano Enzyme Inc.), Protease M "Amano" SD
(Amano Enzyme Co., Ltd.), pandase NP-2 (Yakult Pharmaceutical Industry Co., Ltd.), and the like.

(Method of using composition for improving viability of Bifidobacterium)
The composition for improving the viability of bifidobacteria contains 1.8 mg/m of peptide in a desired medium, food, or the like.
L or more, preferably 1.85 mg/mL or more, more preferably 1.90 mg/mL or more. The following can be exemplified as usage modes.
1) A composition for improving viability of bifidobacteria is added to a medium using bifidobacteria so that the peptide content is 1.8 mg/mL or more, and the medium is sterilized. Bifidobacterium is inoculated into the sterilized medium and cultured at desired temperature and time. The bifidobacterium culture obtained here can be used as a raw material for foods such as fermented milk.
2) A proteolytic enzyme is added to a milk-containing medium so that the peptide content is 1.8 mg/mL or more, and the mixture is incubated to prepare a composition (medium) for improving the viability of bifidobacteria. This composition (medium) for improving survival of bifidobacteria is sterilized. Bifidobacteria are inoculated into the sterilized composition (medium) for improving viability of bifidobacteria, and the bifidobacteria are cultured at a desired temperature and time. The bifidobacterium culture obtained here can be used as a raw material for foods such as fermented milk. For example, fermented milk can be obtained by adding to skim milk powder etc. as a bulk starter.
3) A proteolytic enzyme is added to a medium containing milk so that the amount of the peptide is 1.8 mg/mL or more, and the mixture is incubated to prepare a composition (medium) for improving the viability of bifidobacteria. This composition (medium) for improving survival of bifidobacteria is sterilized. A bulk starter comprising bifidobacteria is added to a sterilized composition (medium) for improving the viability of bifidobacteria, and the mixture is fermented at a desired temperature and time to obtain fermented milk.

In the present invention, if bifidobacteria are cultured in the presence of the composition for improving the viability of bifidobacteria, as in the use mode 2), then the composition for improving the viability of bifidobacteria of the present invention is used. Even if cultured in a medium that does not contain Bifidobacterium, the effect of high viability of bifidobacteria can be obtained. The reason for this is not clear at present, but can be presumed as follows. However, the present invention is not limited to the following presumptions.

It is thought that placing Bifidobacteria in eutrophic conditions at the initial stage of culturing contributes to their subsequent favorable growth. Therefore, it is considered that even under severe conditions such as low temperature, the decrease in the number of bacterial cells can be suppressed.

(target bifidobacteria)
The Bifidobacterium targeted by the composition for improving the viability of Bifidobacterium is not particularly limited as long as it is a bacterium belonging to the genus Bifidobacterium. Fidobacterium bifidum, Bifidobacterium infantis, Bifidobacterium breve, Bifidobacterium animalis, Bifidobacterium addresscentis, Bifidobacterium lactis, Bifidobacterium catenulatum , Bifidobacterium dentium and the like. Examples of strains include Bifidobacterium longum SBT2928 strain and Bifidobacterium pseudolongum SBT2908 strain.

The composition for improving viability of bifidobacteria of the present invention can contain external additives for growing bifidobacteria, such as peptone, yeast extract, and amino acids. These substances can also be added as external additives in order to adjust the peptide concentration, L-amino acid concentration, serine and phenylalanine concentrations. However, in consideration of flavor, it is preferred that these externally added substances are preferably not substantially contained, more preferably not contained at all. The phrase "substantially does not contain" means that the amount does not affect the flavor of the final product.

(Peptide measurement method)
Peptide concentration can be determined by any known method (lowry method, Bradford method, colorimetric method such as BCA method). Commercially available protein concentration measurement reagent (trade name:
DC protein assay kit, manufactured by BIO-RAD) or the like may be used for measurement.

(Method for measuring L-amino acid)
The L-amino acid concentration can be determined by any known method (measurement method using an amino acid quantification enzyme, measurement method using high-performance liquid chromatography or an automatic amino acid analyzer). Commercially available reagent for measuring L-amino acid concentration (trade name: L-Amino Acid Quantitation
Kit, manufactured by Bio Vision) or the like may be used for measurement.

[2] Method for Improving Viability of Bifidobacterium In the method for improving viability of bifidobacteria of the present invention, bifidobacteria are cultured or ferment. Milk protein-derived peptides may be added externally, but in consideration of flavor, it is preferable that they are generated in the medium by adding protease and do not contain externally added peptides.

Preferably, the method for improving the viability of Bifidobacterium of the present invention further comprises producing a total of 0.2 mM or more of phenylalanine and serine in the culture medium. "Producing" includes adding phenylalanine and serine from the outside, but in consideration of flavor, it is produced in the medium by adding a proteolytic enzyme, and does not include anything added from the outside. is preferred.

Bifidobacteria obtained by the method for improving viability of bifidobacteria of the present invention may be used as a starter, or may be used for the preparation of final products such as fermented milk. As described above, when used as a starter, the effect of the present invention can be obtained even if the medium to be added does not contain the composition for improving viability of Bifidobacterium of the present invention.

Examples of the present invention will be described in detail below, but the present invention is not limited to these.

Example 1
(1) Preparation of proteolytic enzyme-treated milk medium and Bifidobacterium longum
culture
Prepare a 15% reduced skim milk medium, add 0.001% of 10 types of proteolytic enzymes that can be used in food, and stir well. The reaction temperature was set by referring to the temperature), and the enzymatic reaction was allowed to stand for 1 hour. Table 1 shows each protease and its enzymatic reaction temperature.

After completion of the enzymatic reaction, the enzyme was deactivated and the medium was sterilized by heat treatment at 95°C for 30 minutes. There, Bifidobacterium longum SBT2928 (Accession number: FERM P-10657, Deposit date: 198
April 13, 1999, National Institute of Advanced Industrial Science and Technology Patent Organism Depository) was added to the final concentration of 1%, and cultured at 36°C for 16 hours.

(2) After confirming the number of bacteria reached in the milk medium , modified A dilution water (0.6% NaHPO4, 0.45% KH2PO4, 0.05% L-cysteinHCl-H2O, 0.05%
Agar, sterilized at 121°C for 15 minutes after dissolution) was used to serially dilute the bacterial solution, which was then mixed with TOS mupirocin medium and cultured using an anaerobic culture system (trade name: Anaeropack, manufactured by Mitsubishi Gas Chemical Company, Inc.). Anaerobically cultured at 37 degrees for 72 hours. After culturing, the number of viable Bifidobacterium longum was measured by the plate count method. Assuming that the number of bacteria reached after 16 hours of culture in the control (medium without treatment with protease) is 1, the relative ratio of the number of bacteria reached in the milk medium containing the survival-improving substance obtained by treatment with protease is shown in Fig. 1. shown in

As a result, compared with the number of bacteria reached by Bifidobacterium longum in the control, the number of bacteria reached was increased by 1.4 to 3.6 times in the milk medium containing the survival-improving substance obtained by the proteolytic enzyme treatment of the present invention. The result was that All of the enzymatic treatments improved the viability of Bifidobacterium longum, but the growth promoting effects of the enzymes varied. Proteax-treated milk medium showed the most growth-promoting effect.

From the above, it was confirmed that Bifidobacterium longum, a species of Bifidobacterium used in food, is improved as a probiotic that exhibits beneficial effects on humans.

Table 1. Protease and Enzyme Reaction Temperature

Example 2
(1) Preparation of proteolytic enzyme-treated milk medium and preparation of bulk starter
Prepare 15% reduced skim milk medium, add 0.001% of 4 types of food-available proteases (Sumizyme LP50D, Proteax, Sumizyme FL-G, Denatzyme AP) to the medium, and mix well. , the enzymatic reaction was carried out by standing for 1 hour near the optimum temperature of the enzyme (the reaction temperature was set with reference to the temperature described in the data sheet issued by each manufacturer) (same temperature conditions as Table 1). After completion of the enzymatic reaction, the enzyme was deactivated and the medium was sterilized by heat treatment at 95°C for 30 minutes.

The peptide concentration in the protease-treated milk medium was 1.9-2.0 mg/mL (Fig. 2
), and the L-amino acid concentration was 4.7-5.0 mM (FIG. 3). Since the amino acid concentration in the control without protease treatment was 4.5 mM, it was considered that 0.2 to 0.5 mM amino acids were produced in the milk medium treated with protease.
In addition, the produced amino acids were phenylalanine and serine. No increase in other amino acids after enzymatic treatment was observed.

Measurement of peptide concentration and L-amino acid concentration and free amino acid composition analysis were carried out by the following methods.
First, the enzyme-inactivated and sterilized milk medium was centrifuged at 15000 rpm for 10 minutes. The obtained supernatant was subjected to a centrifugal filtration device (trade name: Amicon Ultra-0.5 Centrifugal Filter Unit with Ultr
Acel-3 membrane, 10 kD MWCO, manufactured by Millipore) was used for ultrafiltration, and the molecular weight was 10.
Proteins over kDa were removed. After diluting the permeated fraction with ion-exchanged water to an appropriate concentration, the peptide concentration and L-amino acid concentration were measured.

Peptide concentrations were determined according to the Lowry method using a commercially available kit (trade name: DC protein assay kit, manufactured by BIO-RAD). After reagents were added according to the protocol of the kit, color development reaction was performed at room temperature for 15 minutes, and absorbance at 750 nm was measured. Peptide concentrations were calculated based on the obtained absorbance and a previously prepared calibration curve (using bovine serum albumin).

L-amino acid concentration was measured using a commercially available kit (L-Amino Acid Quantitation Kit, Bio-Vision). After adding reagents according to the protocol of the kit, color development reaction was carried out at 37° C. for 30 minutes, and absorbance at 570 nm was measured. The L-amino acid concentration was calculated based on the obtained absorbance and a previously prepared calibration curve (using the standard attached to the kit).
Free amino acid composition analysis was carried out by the following methods. Tryptophan was measured by high-performance liquid chromatography, and free amino acids other than tryptophan were measured by automatic analysis.

Bifidobacterium longum SBT2928 (acceptance number: FERM P-10657, date of deposit: April 13, 1989, National Institute of Advanced Industrial Science and Technology, Patent Organism Depository) ) was added at 1% and cultured at 36°C for 16 hours. After culturing for 16 hours, the bulk starter was quickly cooled to 4°C to obtain a bulk starter. A significant positive correlation was observed between the number of bacteria reaching the bulk starter and the peptide concentration and L-amino acid concentration (p<0.01, Spearman's rank correlation coefficient).

(2) Preparation and storage of fermented milk Mix 12% skimmed milk powder and 2% unsalted butter and mix and dissolve.
The mixture was heat sterilized by holding at 50°C for 5 minutes and cooled to 40°C to prepare a fermented milk base mix. After sterilizing the fermented milk base mix, it was inoculated with 4% Bifidobacterium longum bulk starter prepared in a medium containing the proteolytic enzyme-treated product of the present invention. Furthermore, 0.1% mixed concentrated cells of Lactobacillus delbrueckii subspecies bulgaricus and Streptococcus thermophilus were inoculated. After inoculation, it was fermented at 39 degrees until the acidity reached 0.8. After completion of fermentation, the fermented milk of each sample was dispensed into storage containers and sealed with aluminum lids. It was stored in a refrigerator (10 degrees) for 24 days.

(3) After confirmation of survival in fermented milk , modified A dilution water (0.6% NaHPO4, 0.45% KH2PO4, 0.05% L-cysteinHCl-H2O, 0.05%
Agar, sterilized at 121°C for 15 minutes after dissolution) was used to serially dilute the bacterial solution, which was then mixed with TOS mupirocin medium and cultured using an anaerobic culture system (trade name: Anaeropack, Mitsubishi Gas Chemical Company, Inc.). It was cultured anaerobically for 72 hours. After culturing, the viable count of Bifidobacterium longum was measured by the plate count method, the viable count on the 24th day after storage was divided by the viable count on the first day, and the quotient was converted to %. Survival rate was determined. The results are shown in FIG.

Fermented milk prepared using a bulk starter of Bifidobacterium longum prepared in a medium containing a proteolytic enzyme-treated product resulted in an increased survival rate compared to the control fermented milk.
In addition, assuming that the survival rate of the control was 1, the relative ratio of the survival rate in the fermented milk prepared using the Bifidobacterium longum bulk starter prepared in the medium containing the proteolytic enzyme-treated product was determined. As a result, the survival rate in the refrigerated fermented milk was compared with the control, and the fermented milk prepared using the Bifidobacterium longum bulk starter prepared in the medium containing the proteolytic enzyme-treated product of the present invention However, it improved by 1.8 to 2.1 times.
In addition, the prepared fermented milk had a good flavor, and there was no difference in flavor from the control example.

Example 3
1) 12% powdered skim milk and 2% unsalted butter were mixed and dissolved, heated to 60°C and homogenized.
2) Adjust the homogenized fermented milk base to 65°C, add 0.001% Proteax,
Let it stand for a while.
3) After standing, the mixture was held at 95°C for 15 minutes to heat sterilize and deactivate the enzyme.
4) The enzyme-inactivated fermented milk base was adjusted to 40°C and inoculated with 4% Bifidobacterium longum bulk starter. Furthermore, 0.1% mixed concentrated cells of Lactobacillus delbrueckii subspecies bulgaricus and Streptococcus thermophilus were inoculated.
5) After inoculation, it was fermented at 39°C until the acidity reached 0.8. After completion of fermentation, the fermented milk of each sample was dispensed into storage containers and sealed with aluminum lids. It was stored in a refrigerator (10 degrees) for 24 days.
In addition to the above example products, fermented milk prepared under the same conditions except 2) was prepared as a control.

(1) Confirmation of Viability in Fermented Milk As in Example 2, the viable cell count of Bifidobacterium longum was measured by the plate count method. The number of viable bacteria on the 24th day after storage was divided by the number of viable bacteria on the first day, and the quotient was converted to % to obtain the survival rate. When the survival rate of the control was set to 1, the product of Example improved the survival rate of bifidobacteria by 2.1 times. In addition, the prepared fermented milk had a good flavor, and there was no difference in flavor from the control example.

As described above, the present invention provides a novel composition for improving the viability of bifidobacteria that can be used in foods, without the need to separately add components such as peptides. The viability-improving composition can significantly improve the viability of bifidobacteria during culture and the viability of bifidobacteria during refrigerated storage. As a result, the activity of the bifidobacteria can be maintained at a high level for a long period of time, so that the amount of the bifidobacteria used (the amount added to the food composition) can be reduced, and cost reduction can be expected. In addition, it becomes possible to stably supply and maintain the quality of food compositions containing bifidobacteria.
In addition, since the composition for improving viability in the present invention is obtained by treating a dairy material with a very small amount of an enzyme that can be used in foods, It is possible to ensure the original flavor of milk without affecting it. It is extremely effective against all foods containing bifidobacteria.

Claims (9)

A composition for improving viability of bifidobacteria containing a milk protein hydrolyzate, wherein the improvement in viability is an increase in the number of bacteria reached during culturing of bifidobacteria. A composition for improving the viability of Bifidobacterium containing a milk protein hydrolyzate, wherein the total concentration of L-amino acids in the composition is 4.6 mM or more, and the improvement in viability is achieved by bifidobacterium cells. The above composition, which suppresses the reduction of the number under conditions of 10°C or less. 3. The composition for improving viability of bifidobacteria according to claim 1 or 2, which is a medium for culturing bifidobacteria. 3. The composition for improving survival of Bifidobacterium according to claim 1, wherein the peptide concentration in the composition is 1.8 mg/L or more. The composition for improving viability of Bifidobacterium according to any one of claims 1 to 4, wherein the Bifidobacterium is Bifidobacterium longum. A method for improving the viability of bifidobacteria, characterized by culturing or fermenting bifidobacteria in a culture medium containing 1.8 mg / L or more of milk protein-derived peptides in terms of medium, wherein the viability improvement is an increase in the number of reaching bacteria during culture of bifidobacteria. A method for improving the survival of bifidobacteria, characterized by culturing or fermenting bifidobacteria in a culture medium containing 1.8 mg / L or more of milk protein-derived peptides in terms of medium, wherein L in the culture medium - The method, wherein the amino acid concentration is 4.6 mM or more, and the improvement in viability is suppression of the decrease in the number of Bifidobacterium bacteria under conditions of 10°C or less. The method for improving viability of Bifidobacterium according to claim 6 or 7, wherein the Bifidobacterium is Bifidobacterium longum. The method for improving viability of Bifidobacterium according to any one of claims 6 to 8, further comprising producing a total of 0.2 mM or more of phenylalanine and serine in the culture medium.

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