Method for producing fermented milk containing oligosaccharides

Abstract

This method is for producing fermented milk containing oligosaccharides and a lactic acid bacterium as a living bacterium, and is characterized by culturing the lactic acid bacterium in a medium containing oligosaccharides. By the production method and the fermented milk produced by the production method, the number of living bacteria can be maintained even during long-term preservation in the fermented milk containing oligosaccharides and the lactic acid bacterium as a living bacterium.

Description

[Technical field]

[0001] The present invention relates to a method for producing fermented milk containing oligosaccharides and lactic acid bacteria as live bacteria. [Background technology]

[0002] Fermented milk containing lactic acid bacteria has been known for a long time, and it is also known to add sugars as syrup to impart various effects or sweetness.

[0003] For example, fermented milk containing live lactic acid bacteria and oligosaccharides as sugars is known, and this is known to have excellent intestinal reachability (Patent Document 1).

[0004] However, although fermented milk containing live lactic acid bacteria and oligosaccharides has excellent intestinal accessibility as described above, it was found that when oligosaccharides are added as a syrup, it is more difficult to maintain a high number of live bacteria during long-term storage than when sugars other than oligosaccharides are added as a syrup. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent No. 2571734 Summary of the Invention [Problem to be solved by the invention]

[0006] Therefore, an object of the present invention is to provide a technology that can maintain a high viable cell count in fermented milk containing oligosaccharides and lactic acid bacteria as viable bacteria even during long-term storage. [Means for solving the problem]

[0007] As a result of intensive research into solving the above problems, the inventors discovered that when producing fermented milk containing oligosaccharides and live lactic acid bacteria, the above problems can be solved by adding oligosaccharides to the culture medium when culturing the lactic acid bacteria, rather than adding them as a syrup as in the conventional method, and thus completed the present invention.

[0008] That is, the present invention is a method for producing fermented milk containing oligosaccharides and lactic acid bacteria as live bacteria, characterized in that the lactic acid bacteria are cultured in a medium containing oligosaccharides.

[0009] The present invention also relates to fermented milk produced by the above-mentioned method for producing fermented milk.

[0010] Furthermore, the present invention relates to a method for improving the survival rate of lactic acid bacteria in fermented milk containing oligosaccharides and viable lactic acid bacteria, which comprises culturing the lactic acid bacteria in a medium containing oligosaccharides. Effect of the Invention

[0011] The method for producing fermented milk of the present invention is a simple method in which oligosaccharides are added to the medium for culturing lactic acid bacteria, so that no new equipment is required and existing equipment can be used as is.

[0012] The fermented milk produced by the method of the present invention not only maintains a high viable cell count during long-term storage, but also has a better flavor and an enhanced sense of health.

[0013] In particular, the fermented milk obtained by the method for producing fermented milk of the present invention is a so-called synbiotic, in that it allows the intake of probiotics made from lactic acid bacteria together with prebiotics made from oligosaccharides (which increase the number of lactic acid bacteria in the intestines), further enhancing the probiotics' ability to protect intestinal health. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] The method for producing fermented milk of the present invention (hereinafter referred to as "the method of the present invention") is a method for producing fermented milk containing oligosaccharides and lactic acid bacteria as live bacteria, in which the lactic acid bacteria are cultured in a medium containing oligosaccharides.

[0015] The oligosaccharides used in the present invention are not particularly limited, and examples thereof include maltooligosaccharides, fructooligosaccharides, and galactooligosaccharides. The oligosaccharides used in the present invention refer to transfer disaccharides or trisaccharides or more. Among these oligosaccharides, those containing galactose in the sugar chain are preferred, galactooligosaccharides are more preferred, and galactooligosaccharides mainly composed of 4'-GL are particularly preferred. Examples of such galactooligosaccharides include Oligomate 55N (manufactured by Yakult Pharmaceutical Co., Ltd.: Brix sugar content 75.0 to 76.0), which is a mixture of 56.4% galactooligosaccharides mainly composed of 4'-GL and 43% other sugars.

[0016] The oligosaccharide is contained in the medium described below at a concentration of 1.0% by mass (hereinafter simply referred to as "%) or more, preferably 5.0% or more, more preferably 5 to 20%, and particularly preferably 5 to 15%.

[0017] The medium used in the method of the present invention is not particularly limited as long as it is a medium in which lactic acid bacteria can grow, and examples thereof include animal milk mediums made from raw milk such as cow's milk, goat's milk, horse's milk, and sheep's milk, and dairy products such as skim milk powder, whole milk powder, and fresh cream, and various synthetic media. Among these media, skim milk powder is preferred.

[0018] The medium may contain carbohydrates that can be assimilated by lactic acid bacteria, if necessary. Examples of such carbohydrates include glucose, sucrose, fructose, etc. The content of carbohydrates that can be assimilated by lactic acid bacteria in the medium is not particularly limited and may be appropriately set according to the lactic acid bacteria used for the culture, and is, for example, 0.1 to 20%, preferably 1 to 10%.

[0019] If necessary, the above medium may further contain culture aids such as sweet tea extract, oolong tea extract, green tea extract, black tea extract, jasmine tea extract, oleic acid, etc. These culture aids can be used alone or in combination of two or more kinds.

[0020] Among the culture aids, sweet tea extract, oolong tea extract, green tea extract, black tea extract, and jasmine tea extract may be commercially available or may be obtained by the methods described in JP 2001-178413 A, JP 2016-174589 A, etc. The content of these extracts in the medium is not particularly limited, but for example, sweet tea extract and oolong tea extract are 0.1 to 2%, preferably 0.22 to 0.33%.

[0021] Among the culture aids, the oleic acids are not particularly limited, and examples thereof include free oleic acid, inorganic salts of oleic acid, and sugar esters, glycerides, sorbitan esters, propylene glycol esters, and the like, which are commonly used as emulsifiers, in which the fatty acid portion is oleic acid. It is also possible to use food materials that contain a large amount of oleic acids.

[0022] Specific examples of oleic acids include salts of oleic acid such as sodium oleate and potassium oleate, and oleic acid esters such as glycerin oleate, polyglycerin oleate, and sucrose oleate. One or more of these oleic acids can be used.

[0023] The content of oleic acids in the medium is not particularly limited, but is, for example, 5 to 200 ppm, and preferably 10 to 100 ppm.

[0024] Furthermore, the above medium may contain components that can be added to media typically used for culturing lactic acid bacteria, such as vitamins such as vitamin A, B vitamins, vitamin C, and vitamin E, peptides such as milk peptides, amino acids, salts such as calcium and magnesium, and sugars.

[0025] The medium may contain oligosaccharides and culture lactic acid bacteria as is, but it is preferable to adjust the osmotic pressure, since this improves fermentability and increases both the number of bacteria after culture and the number of bacteria after storage. The osmotic pressure of the medium is 500 to 1400 mOsm, preferably 800 to 1200 mOsm. There are no particular limitations on the method for adjusting the osmotic pressure, and examples include a method of adjusting the amount of oligosaccharides or sugars contained in the medium. Note that good fermentability means that the acidity after culture is 24 or more and the number of bacteria is 5.0 x 10 9 This refers to cfu / ml or higher.

[0026] A preferred embodiment of the medium containing oligosaccharides used in the method of the present invention is as follows: Skim milk powder 10~20% Oolong tea extract 0.1~2% Oligosaccharides 1-20% Glucose 0.1~20%

[0027] The lactic acid bacteria used in the present invention are not particularly limited, and may be, for example, any of those found in nature, those deposited in a depository institution, those commercially available, or those mutated from these. Specifically, Lactobacillus casei, Lactobacillus gasseri, Lactobacillus acidophilus, Lactobacillus cremoris, Lactobacillus helveticus, Lactobacillus salivarius, Lactobacillus fermentum, Lactobacillus eugleni, Lactobacillus delbrueckii subsp. bulgaricus, Lactobacillus delbrueckii subsp. delbrueckii, Lactobacillus johnsonii, and other lactic acid bacteria of the genus Lactobacillus, such as Streptococcus thermophilus, Lactococcus lactis subsp. lactis, Lactococcus ... Examples of such lactic acid bacteria include lactobacilli of the genus Lactococcus, such as Lactococcus subsp. cremoris, Lactococcus plantarum, and Lactococcus raffinolactis, and lactobacilli of the genus Enterococcus, such as Enterococcus faecalis and Enterococcus faecium. Among these lactic acid bacteria, preferred are lactic acid bacteria that do not substantially assimilate oligosaccharides, such as Lactobacillus casei, Lactobacillus gasseri, Lactobacillus acidophilus, and Streptococcus thermophilus. Here, "not substantially assimilating oligosaccharides" means that the bacteria do not have the ability to assimilate trisaccharides or more. The assimilation ability can be confirmed by a known method, such as a method of confirming the presence or absence of colonies or the turbidity of the medium after culturing in a medium containing only oligosaccharides as a sugar source. Furthermore, among lactic acid bacteria that do not substantially assimilate oligosaccharides, Lactobacillus lactic acid bacteria are preferred, such as Lactobacillus casei. In particular, Lactobacillus casei YIT9029 (FERM BP-1366, date of receipt: January 12, 1981) is preferred among lactic acid bacteria of the Lactobacillus lactic acid bacteria. These lactic acid bacteria can be used alone or in combination of two or more kinds.

[0028] The lactic acid bacteria with the above-mentioned date of deposit listed have been deposited at the National Institute of Technology and Evaluation, Patent Organism Depositary (Room 120, 2-5-8 Kazusa Kamatari, Kisarazu City, Chiba Prefecture, 292-0818, Japan).

[0029] In the method of the present invention, the conditions for culturing lactic acid bacteria in a medium containing oligosaccharides are not particularly limited and may be appropriately determined depending on the type of lactic acid bacteria used.

[0030] Specifically, when lactic acid bacteria are cultured in a medium containing oligosaccharides, the number of bacteria in the medium is 0.5 × 10 6 The culture conditions include inoculating the mixture to a concentration of about cfu / ml and culturing the mixture at the optimal culture temperature for the lactic acid bacteria, etc., described above, until the pH reaches about 3.5 to 3.6 or the acidity reaches about 24.0. The culture conditions may be selected appropriately from among static culture, stirring, shaking, aeration, etc., and are suitable for the culture of the lactic acid bacteria used.

[0031] The fermented milk containing the oligosaccharides and the live lactic acid bacteria obtained after the culture may be used as the final product as it is, or oligosaccharides may be further added to the milk. In this case, the amount of oligosaccharides added is not particularly limited, but is 1 to 20%, preferably 3 to 10%, of the final product.

[0032] Furthermore, if necessary, food ingredients such as carbohydrates, sugar alcohols, high-intensity sweeteners, thickeners, emulsifiers, vitamins, flavors, etc. can be blended into the fermented milk by conventional methods.

[0033] Examples of the food ingredients include carbohydrates such as sucrose, glucose, fructose, palatinose, trehalose, lactose, xylose, and maltose; sugar alcohols such as sorbitol, xylitol, erythritol, lactitol, palatinit, reduced starch syrup, and reduced maltose starch syrup; high-intensity sweeteners such as aspartame, thaumatin, sucralose, acesulfame K, and stevia; various thickening (stabilizing) agents such as agar, gelatin, carrageenan, guar gum, xanthan gum, pectin, locust bean gum, gellan gum, carboxymethylcellulose, soybean polysaccharides, and propylene glycol alginate; sucrose fatty acid esters, glycerin fatty acid esters, and the like. Examples of suitable flavors include emulsifiers such as ester, polyglycerol fatty acid esters, sorbitan fatty acid esters, and lecithin; milk fats such as cream, butter, and sour cream; acidulants such as citric acid, lactic acid, acetic acid, malic acid, tartaric acid, and gluconic acid; various vitamins such as vitamin A, vitamin B, vitamin C, and vitamin E; minerals such as calcium, magnesium, zinc, iron, and manganese; and flavors such as yogurt, berry, orange, quince, shiso, citrus, apple, mint, grape, apricot, pear, custard cream, peach, melon, banana, tropical, herb, black tea, and coffee.

[0034] The fermented milk containing the oligosaccharides and lactic acid bacteria as live bacteria described above includes not only fermented milk as specified by the Ministerial Ordinance on Milk, etc., but also live bacteria-containing beverages such as dairy lactic acid bacteria beverages and lactic acid bacteria beverages, kefir, yogurt, etc. Also, the form of the fermented milk may be, for example, a hard type, a soft type, a plain type, a sweet type, a fruit type, a drink type, a frozen type, etc.

[0035] The fermented milk has improved survival rate of lactic acid bacteria, and can maintain a high viable cell count during long-term storage. Specifically, the fermented milk has a survival rate of 95% or more when stored at 10° C. or lower for 25 days. The survival rate is a value measured by the method described in the Examples.

[0036] The fermented milk has an enhanced sense of healthiness. The healthy flavor of fermented milk is a flavor that is not excessively sweet and has a moderate sourness that occurs with the fermentation of lactic acid bacteria, and that can give the impression of being low in calories, low in sugar, and typical of fermented milk. EXAMPLES

[0037] The present invention will be described in detail below with reference to examples, but the present invention is not limited to these examples in any way.

[0038] Reference example 1 Traditional fermented milk production: A medium containing 14.7% skim milk powder, 9.2% glucose fructose liquid sugar, and 0.14% oolong tea extract (YOE-N: Yakult Materials Co., Ltd.) dissolved in water was sterilized at 100°C for 60 minutes. A 0.5% starter of Lactobacillus casei YIT9029 (FERM BP-1366) was inoculated into the medium (initial bacterial count: 5.0 × 10 6 cfu / ml), and the temperature was adjusted while culturing until the acidity reached 24.3. The obtained fermented milk was mixed with a stabilizer solution containing 2.9% skim milk powder and 2.7% soybean polysaccharide stabilizer (SM-YT, Fuji Oil Co., Ltd.) and homogenized, then mixed with sucrose syrup or galactooligosaccharide liquid sugar (a mixture of 56.4% galactooligosaccharide and 43% other sugars per solid content: Oligomate 55N: Yakult Pharmaceutical Co., Ltd.) shown in Table 1, and the viable cell count was increased to 1.4 × 10 9 The lactobacillus beverages obtained had cfu / ml, an acidity of 5.8, and a pH of 3.7 (Products 1 and 2). The lactobacillus beverages were placed in containers and stored at 10°C, after which the survival rates were measured using the following method. The results are shown in Table 1.

[0039] <Acidity measurement method> 40 g of ion-exchanged water was added to 9 g of the culture, and the mixture was neutralized with 0.1 N sodium hydroxide to adjust the pH to 8.5. The titration value (unit: ml / 9 g) was taken as the acidity.

[0040] <Osmotic pressure measurement method> Measurements were taken using an osmotic pressure analyzer, "OsmoStation OM-6060," manufactured by Arkray, Inc.

[0041] <Viable bacteria count measurement method> Measurements were performed using BCP medium (Eiken Chemical Co., Ltd.).

[0042] <Survival rate calculation method> Survival rate (%) on Xth day of storage = (number of viable bacteria on Xth day of storage / number of viable bacteria on 0th day of storage) x 100

[0043] [Table 1]

[0044] When galactooligosaccharide was added as a syrup to the fermented milk after fermentation, the survival rate was lower than when sucrose was added as a syrup to the fermented milk after fermentation.

[0045] Example 1 Production of fermented milk: A medium containing 14.6% skim milk powder, 0.14% oolong tea extract (YOE-N: Yakult Materials Co., Ltd.), and 19.5% galactooligosaccharide liquid sugar (a mixture of 56.4% galactooligosaccharide and 43% other sugars per solid content: Oligomate 55N: Yakult Pharmaceutical Co., Ltd.) dissolved in water was sterilized at 100°C for 60 minutes. A starter of Lactobacillus casei YIT9029 (FERM BP-1366) was inoculated into the medium at 0.5% (initial cell count: 5.0 × 10 6 The culture was continued at 100°C for 1 h at 20°C (100°F / ml) while adjusting the temperature until the acidity reached 24.3. The obtained fermented milk was mixed with a stabilizer solution containing 2.9% skim milk powder and 2.7% soybean polysaccharide (SM-YT, Fuji Oil Co., Ltd.) as a stabilizer and homogenized, and then mixed with a syrup containing 16.1% galactooligosaccharide liquid sugar shown in Table 2. The viable cell count was increased to 6.3 × 10 8A lactobacillus beverage with cfu / ml, titratable acidity of 4.9ml / 9g, and pH of 3.8 was obtained (Product 1). This lactobacillus beverage was placed in a container and stored at 10°C, after which the survival rate was measured using the method described above. The results are shown in Table 2. Product 2 produced in Reference Example 1 was used for comparison.

[0046] [Table 2]

[0047] The survival rate was significantly higher when galactooligosaccharides were added to the medium than when they were added as syrup to the fermented milk after fermentation.

[0048] Example 2 Production of fermented milk: A medium containing 14.6% skim milk powder, 0.14% oolong tea extract (YOE-N: Yakult Materials Co., Ltd.), and 12.8% galactooligosaccharide liquid sugar (a mixture of 56.4% galactooligosaccharide and 43% other sugars per solid content: Oligomate 55N: Yakult Pharmaceutical Co., Ltd.) dissolved in water was sterilized at 100°C for 60 minutes. A 0.5% starter of Lactobacillus casei YIT9029 (FERM BP-1366) was inoculated into the medium (initial cell count: 5.0×10cfu / ml), and the medium was cultured while adjusting the temperature until the acidity reached 24.3. The obtained fermented milk was mixed with a stabilizer solution containing 2.9% skim milk powder and 2.7% soybean polysaccharide (SM-YT, Fuji Oil Co., Ltd.) as a stabilizer, and homogenized. The mixture was then mixed with a syrup containing 18.3% galactooligosaccharide liquid sugar shown in Table 3, and the viable cell count was increased to 1.2 × 10 9A lactic acid bacteria drink with cfu / ml, titratable acidity of 5.6, and pH of 3.7 was obtained (Product 2). This lactic acid bacteria drink was placed in a container and stored at 10°C, after which the viable bacteria count (and survival rate) was measured using the method described above. The results are shown in Table 3. For comparison, Product 3, in which the galactooligosaccharides added to the medium were replaced with 2.3% glucose and 0.014% sucralose, and Product 4, in which the galactooligosaccharides were replaced with 2.3% glucose and 10.8% maltitol, were used. The fermentability of these products was also evaluated using the following evaluation criteria. The results are also shown in Table 3.

[0049] <Fermentation evaluation criteria> (Evaluation)(Content) ○: Acidity after incubation is 24 or higher and viable cell count is 5.0×10 9 cfu / ml or more △: Acidity after incubation is 24 or higher and viable cell count is 5.0×10 9 Less than cfu / ml ×: Acidity after incubation is less than 24

[0050] [Table 3]

[0051] It was found that by adjusting the osmotic pressure of the medium between 800 and 1200 mOsm, the fermentability was improved and both the number of bacteria after cultivation and the number of bacteria after storage increased (Product 2). In addition, when sucralose or maltitol other than galactooligosaccharide was added to the medium, the acidity after cultivation did not reach the target, which is thought to have had a negative effect on the fermentability, and the acidity of the product did not reach the target either (Products 3 and 4).

[0052] Example 3 Production of fermented milk: A medium containing 14.6% skim milk powder, 0.14% oolong tea extract (YOE-N: Yakult Materials Co., Ltd.), and 12.8% galactooligosaccharide liquid sugar (a mixture of 56.4% galactooligosaccharide and 43% other sugars per solid content: Oligomate 55N: Yakult Pharmaceutical Co., Ltd.) dissolved in water was sterilized at 100°C for 60 minutes. A starter of Lactobacillus casei YIT9029 (FERM BP-1366) was inoculated into the medium at 0.5% (initial cell count: 5.0 × 10 6 The culture was continued at 100°C for 1 h at 20°C (cfu / ml) while adjusting the temperature until the acidity reached 24.3. The obtained fermented milk was mixed with a stabilizer solution containing 2.9% skim milk powder and 2.7% soybean polysaccharide (SM-YT, Fuji Oil Co., Ltd.) as a stabilizer and homogenized, and then mixed with a syrup containing 0.02% stevia and 18.3% galactooligosaccharide liquid sugar shown in Table 4, and the viable cell count was increased to 1.2 × 10 9 A lactobacillus beverage with cfu / ml, titratable acidity of 5.2, and pH of 3.8 was obtained (Product 3). This lactobacillus beverage was placed in a container and stored at 10°C, after which the viable cell count (and survival rate) was measured using the method described above. The results are shown in Table 4. The comparison subject was Product 5, in which the galactooligosaccharide added to the medium was replaced with 9.2% glucose fructose liquid sugar. The product acidity of Products 3 and 5 was unified to 5.2 and the relative sweetness to 110. Here, the relative sweetness is a relative value when the sweetness level of a 10 w / v% sucrose aqueous solution is taken as 100. Furthermore, the sweetness, sourness, and healthiness of these products were evaluated using the following evaluation criteria, and the flavor was also evaluated by free description. The results are also shown in Table 4.

[0053] <Sweetness and sourness evaluation criteria> (Score)(Content) 1: Weak 2: Slightly weak 3: Just right 4: Somewhat strong 5: Strong

[0054] <Criteria for assessing health> (Score)(Content) 1: No 2: Not very often 3: Neither 4: Somewhat 5: Yes

[0055] [Table 4]

[0056] Usually, when fermented milk has a relatively stronger sourness than sweetness, it leads to a decrease in palatability, but if the sweetness is too strong, it will lose the clean, refreshing taste and healthy flavor image that are desired for fermented milk and lactic acid bacteria drinks. Product 5 has a strong sweetness from glucose fructose liquid sugar, which leads to an impression of high calories and reduces the sense of health, but by using only galactooligosaccharide liquid sugar as the sugar ingredient, product 3 does not have excessive sweetness, has a clean taste that is balanced with the sourness, and leads to a sense of health. [Industrial Applicability]

[0057] INDUSTRIAL APPLICABILITY The present invention can be utilized for producing fermented milk containing oligosaccharides and lactic acid bacteria as viable bacteria, which can maintain a high viable cell count even during long-term storage.

Claims

1. A method for producing fermented milk containing oligosaccharides and live lactic acid bacteria, comprising culturing lactic acid bacteria in a medium containing oligosaccharides, The osmotic pressure of the medium containing the oligosaccharides during culture is 800 to 1200 mOsm; the oligosaccharide is a galactooligosaccharide, The lactic acid bacteria is Lactobacillus casei, which does not substantially assimilate oligosaccharides.

1. A method for producing fermented milk containing oligosaccharides and lactic acid bacteria as live bacteria, comprising:

2. 2. The method according to claim 1, wherein the oligosaccharide is further added after culturing the lactic acid bacteria in the medium containing the oligosaccharide.

3. 3. The method for producing fermented milk according to claim 1 or 2, wherein the oligosaccharide content in the medium is 5.0% by mass or more.

4. A method for improving the viability of lactic acid bacteria in fermented milk containing oligosaccharides and lactic acid bacteria as viable bacteria by culturing the lactic acid bacteria in a medium containing oligosaccharides, comprising: The osmotic pressure of the medium containing the oligosaccharides during culture is 800 to 1200 mOsm; the oligosaccharide is a galactooligosaccharide, The lactic acid bacteria is Lactobacillus casei, which does not substantially assimilate oligosaccharides. A method for improving the survival rate of lactic acid bacteria in fermented milk containing oligosaccharides and lactic acid bacteria as live bacteria, comprising:

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