EA048587B1 - COMPOSITION AND METHOD FOR PRODUCING A FERMENTED MILK PRODUCT INCLUDING THE USE OF A LACTOSE-DEFICIENT STRAIN OF S. THERMOPHILUS, A LACTOSE-DEFICIENT STRAIN OF L. BULGARICUS AND A PROBIOTIC STRAIN - Google Patents

Description

Field of invention

The present invention relates to a composition and a method for producing a fermented milk product.

Prior art

EP-A1-2957180 discloses a method for producing a fermented milk product using lactose-deficient lactic acid bacteria, in particular lactose-deficient strains of Streptococcus thermophilus and strains of Lactobacillus delbrueckii subsp. bulgaricus, which are capable of metabolizing non-lactose carbohydrates.

In the fermentation of milk using a starter culture containing lactose-deficient lactic acid bacteria, a non-lactose carbohydrate such as sucrose, glucose or galactose is added to the milk base at the beginning of the fermentation in an amount measured so that it is exhausted at the target pH and therefore leads to the cessation of the growth of lactic acid bacteria and the cessation of fermentation. In this way, subsequent acidification during subsequent storage is significantly reduced or even completely prevented.

However, when it is desired to produce fermented milk products containing added sucrose to sweeten the product, there is a risk that this will result in an unacceptable degree of subsequent acidification during storage, particularly at elevated temperatures.

Probiotic strains such as the Lactobacillus rhamnosus strain LGG® deposited as ATCC53103 are widely used in fermented milk products. However, in many fermented milk products, probiotic strains grow during storage, particularly at elevated temperatures, which can lead to undesirable subsequent acidification.

Brief summary of the invention

The objective of the present invention is to propose a composition for producing a fermented milk product with improved subsequent oxidation properties.

The objective of the present invention is to obtain a composition for the production of a fermented milk product containing

1) a starter culture of lactic acid bacteria containing at least one lactose-deficient strain of Streptococcus thermophilus that is capable of metabolizing a non-lactose carbohydrate, and at least one lactose-deficient strain of Lactobacillus delbrueckii subsp. bulgaricus that is capable of metabolizing a non-lactose carbohydrate, and

2) a probiotic strain selected from the group consisting of a Lactobacillus strain and a Bifidobacterium strain.

The present invention is based on the unexpected experimental discovery that, when using a starter culture consisting of lactose-deficient strains in combination with a probiotic strain, problems associated with subsequent acidification associated with both said starter culture and said probiotic strain are significantly reduced. In particular, when a sweetening carbohydrate such as sucrose is added to a fermented milk product, the level of subsequent acidification caused by the starter during storage of the fermented milk product is greatly reduced. The level of subsequent acidification caused by the probiotic strain is also greatly reduced during storage of the fermented milk product.

In addition, when fermenting a milk base to obtain a fermented milk product, the composition according to the invention requires a shorter fermentation time compared to the corresponding composition that does not contain a probiotic strain.

The present invention also relates to a method for producing a fermented milk product, comprising the following stages:

1) adding to the milk base a starter culture of lactic acid bacteria containing at least one lactose-deficient strain of Streptococcus thermophilus that is capable of metabolizing a non-lactose carbohydrate and at least one lactose-deficient strain of Lactobacillus delbrueckii subsp. bulgaricus that is capable of metabolizing a non-lactose carbohydrate,

2) fermentation of the milk base for a certain period of time until the target pH is reached, producing a fermented milk product, and

3) adding a probiotic strain selected from the group consisting of a Lactobacillus strain and a Bifidobacterium strain to the process.

Detailed description of the invention

Lactose-deficient lactic acid bacteria.

The terms lactose metabolism deficiency and lactose-deficient are used in the context of the present invention to characterize LAB (lactic acid bacteria) that have either partially or completely lost the ability to utilize lactose as a source of cell growth or to maintain cell viability. The corresponding LAB are capable of metabolizing one or more carbohydrates selected from sucrose, galactose and/or glucose or another fermentable carbohydrate. Since these carbohydrates are not naturally present in milk in an amount sufficient to support fermentation by lactose-deficient mutants, it is necessary to add such carbohydrates to the milk. Lactose-deficient and partially deficient LAB can be characterized as

- 1 048587 white colonies on medium containing lactose and X-Gal (5-bromo-4-chloro-3-indolyl-beta-D-galactopyranoside).

In a specific embodiment of the invention, the lactose-deficient strain is capable of metabolizing a non-lactose carbohydrate selected from the group consisting of sucrose, galactose and glucose, preferably sucrose. In a specific embodiment of the invention, the lactose-deficient strain is capable of metabolizing galactose.

In a specific embodiment of the invention, the lactose-deficient strain of Streptococcus thermophilus is selected from the group consisting of (a) (1) the strain deposited in the DSMZ - Deutsche Sammlung von Mikroorganismen und Zellkulturen GmbH, Inhoffenstr. 7B, D-38124 Braunschweig, 2014-06-12, with the registration number DSM 28952;

(2) a strain derived from DSM 28952, which is further characterized by the ability to form white colonies on a medium containing lactose and X-Gal;

(b) (1) the strain deposited in DSMZ - Deutsche Sammlung von Mikroorganismen und Zellkulturen GmbH, Inhoffenstr. 7B, D-38124 Braunschweig, 2014-06-12 with the registration number DSM 28953;

(2) a strain derived from DSM 28953, which is further characterized by the ability to form white colonies on a medium containing lactose and X-Gal;

(c) (1) the strain deposited in DSMZ - Deutsche Sammlung von Mikroorganismen und Zellkulturen GmbH, Inhoffenstr. 7B, D-38124 Braunschweig, 2017-08-22 with the registration number DSM 32599;

(2) a strain derived from DSM 32599, which is further characterized by the ability to form white colonies on a medium containing lactose and X-Gal; and (d) (1) a strain deposited at DSMZ - Deutsche Sammlung von Mikroorganismen und Zellkulturen GmbH, Inhoffenstr. 7B, D-38124 Braunschweig, 2017-08-22 with the accession number DSM 32600; and (2) a strain derived from DSM 32600, which is further characterized by the ability to form white colonies on a medium containing lactose and X-Gal.

In a specific embodiment of the invention, the lactose-deficient strain of Streptococcus thermophilus is selected from the group consisting of (a) (1) the strain deposited in the DSMZ - Deutsche Sammlung von Mikroorganismen und Zellkulturen GmbH, Inhoffenstr. 7B, D-38124 Braunschweig, 2014-06-12 with the registration number DSM 28952;

(2) a strain derived from DSM 28952, which is further characterized by the ability to form white colonies on a medium containing lactose and X-Gal; and (b) (1) a strain deposited at DSMZ - Deutsche Sammlung von Mikroorganismen und Zellkulturen GmbH, Inhoffenstr. 7B, D-38124 Braunschweig, 2014-06-12 with the accession number DSM 28953; and (2) a strain derived from DSM 28953, which is further characterized by the ability to form white colonies on a medium containing lactose and X-Gal.

In a specific embodiment of the invention, the lactose-deficient strain of Streptococcus thermophilus is selected from the group consisting of (c) (1) the strain deposited in the DSMZ - Deutsche Sammlung von Mikroorganismen und Zellkulturen GmbH, Inhoffenstr. 7B, D-38124 Braunschweig, 2017-08-22 with the registration number DSM 32599;

(2) a strain derived from DSM 32599, which is further characterized by the ability to form white colonies on a medium containing lactose and X-Gal; and (d) (1) a strain deposited at DSMZ - Deutsche Sammlung von Mikroorganismen und Zellkulturen GmbH, Inhoffenstr. 7B, D-38124 Braunschweig, 2017-08-22 with the accession number DSM 32600; and (2) a strain derived from DSM 32600, which is further characterized by the ability to form white colonies on a medium containing lactose and X-Gal.

In a specific embodiment of the invention, the lactose-deficient strain of Lactobacillus delbrueckii subsp. bulgaricus is selected from the group consisting of (1) a strain deposited in the DSMZ - Deutsche Sammlung von Mikroorganismen und Zellkulturen GmbH, Inhoffenstr. 7B, D-38124 Braunschweig, 2014-06-12 with the registration number DSM 28910; and (2) a strain derived from DSM 28910, which is further characterized by the ability to form white colonies on a medium containing lactose and X-Gal.

Probiotic strain.

The term probiotic bacteria refers to viable bacteria that are administered to a consumer in sufficient quantities to achieve a health benefit in the consumer. The probiotic bacteria are capable of surviving in the gastrointestinal tract after ingestion and colonizing the intestine of the consumer. In a particular embodiment of the invention, the probiotic strain of the present invention is selected from the group consisting of bacteria of the genus Lactobacillus such as Lactobacillus acidophilus, Lactobacillus paracasei, Lactobacillus rhamnosus, Lactobacillus casei, Lactobacillus delbrueckii, Lactobacillus lactis, Lactobacillus plantarum, Lactobacillus reuteri and Lactobacillus johnsonii, the genus Bifidobacterium such as Bifidobacterium longum, Bifidobacterium adolescentis, Bifidobacterium bifidum, Bifidobacterium breve, Bifidobacterium animalis subsp. lactis, Bifidobacterium dentium, Bifidobacterium catenulatum, Bifidobacterium angulatum, Bifidobacterium magnum, Bifidobacterium pseudocatenulatum and Bifidobacterium infantis, and the like.

- 2 048587

In a specific embodiment of the invention, the probiotic strain of Lactobacillus is selected from the group consisting of Lactobacillus acidophilus, Lactobacillus paracasei, Lactobacillus rhamnosus, Lactobacillus casei, Lactobacillus delbrueckii, Lactobacillus lactis, Lactobacillus plantarum, Lactobacillus reuteri and Lactobacillus johnsonii.

In a specific embodiment of the invention, the probiotic strain of Lactobacillus is selected from the group consisting of the strain of Lactobacillus rhamnosus and the strain of Lactobacillus paracasei.

In a specific embodiment of the invention, the probiotic strain is the Lactobacillus rhamnosus LGG® strain deposited as ATCC53103.

In a specific embodiment of the invention, the probiotic strain is Lactobacillus paracasei strain CRL 431, deposited as ATCC 55544.

In a specific embodiment of the invention, the probiotic strain of Bifidobacterium is selected from the group consisting of Bifidobacterium longum, Bifidobacterium adolescentis, Bifidobacterium bifidum, Bifidobacterium breve, Bifidobacterium animalis subsp. lactis, Bifidobacterium dentium, Bifidobacterium catenulatum, Bifidobacterium angulatum, Bifidobacterium magnum, Bifidobacterium pseudocatenulatum and Bifidobacterium infantis.

In a specific embodiment of the invention, the probiotic strain of Bifidobacterium is the strain Bifidobacterium animalis subsp. lactis BB-12, deposited as DSM15954.

Composition according to the invention

In a specific embodiment, the composition comprises two or more lactose-deficient strains of Streptococcus thermophilus and one lactose-deficient strain of Lactobacillus delbrueckii subsp. bulgaricus.

In a specific embodiment of the composition, the non-lactose carbohydrate is selected from the group consisting of sucrose, galactose and glucose.

In a particular embodiment of the present invention, the composition comprises from 10 to 10 ¹² CFU (colony forming units)/g of the Streptococcus thermophilus strain, such as from 105 to 10 ¹¹ CFU/g, such as from 10 ⁶ to 10 ¹⁰ CFU/g or such as from 10 ⁷ to 109 CFU/g of the Streptococcus thermophilus strain.

In a particular embodiment, the composition further comprises from 10 ⁴ to 10 ¹² CFU/g of the Lactobacillus delbrueckii subsp. bulgaricus strain, such as from 10 5 to 10 ¹¹ CFU/g, such as from 10 ⁶ to 10 ¹⁰ CFU/g or such as from 10 ⁷ to 109 CFU/g of the Lactobacillus delbrueckii subsp. bulgaricus strain.

Lactobacillus delbrueckii subsp. bulgaricus, Streptococcus thermophilus and other lactic acid bacteria are commonly used as starters for technological purposes in the production of various food products, such as in the dairy industry, such as for fermented milk products. Thus, in another preferred embodiment, the composition is suitable for use as a starter.

The starters can be created as frozen or dried starters in addition to liquid starters. Thus, in another preferred embodiment, the composition is in frozen, freeze-dried or liquid form.

As disclosed in WO 2005/003327, it is useful to add certain cryoprotective agents to the starter. Thus, the starter composition of the present invention may comprise one or more cryoprotective agents selected from the group consisting of inosine 5'-monophosphate (IMP), adenosine 5'-monophosphate (AMP), guanosine 5'-monophosphate (GMP), uranosine 5'-monophosphate (UMP), cytidine 5'-monophosphate (CMP), adenine, guanine, uracil, cytosine, adenosine, guanosine, uridine, cytidine, hypoxanthine, xanthine, hypoxanthine, orotidine, thymidine, inosine and a derivative of any of these compounds.

The method according to the invention

The present invention also relates to a method for producing a fermented milk product, comprising the following stages:

1) adding to the milk base a starter culture of lactic acid bacteria containing at least one lactose-deficient strain of Streptococcus thermophilus that is capable of metabolizing a non-lactose carbohydrate and at least one lactose-deficient strain of Lactobacillus delbrueckii subsp. bulgaricus that is capable of metabolizing a non-lactose carbohydrate,

2) fermentation of the milk base for a certain period of time until the target pH is reached, producing a fermented milk product, and

3) adding a probiotic strain selected from the group consisting of a Lactobacillus strain and a Bifidobacterium strain to the process.

In a specific embodiment of the invention, the lactose-deficient strains are capable of metabolizing a non-lactose carbohydrate selected from the group consisting of sucrose, galactose and glucose, preferably sucrose.

In a specific embodiment of the invention, a non-lactose carbohydrate is added to the milk base at the beginning of the fermentation stage.

In a specific embodiment of the invention, the fermentation step is completed by a method selected from the group consisting of 1) acidification of the fermented milk product, rendering at least one strain of the starter unable to grow, 2) cooling, and 3) depletion of the non-lactose carbohydrate.

Preferably, the non-lactose carbohydrate is added to the milk base in an amount measured

- 3 048587 in such a way that it is exhausted and therefore leads to a cessation of the growth of lactic acid bacteria and a cessation of fermentation. Preferably, the non-lactose carbohydrate is added to the milk base in an amount measured in such a way that it is exhausted at the target pH and therefore leads to a cessation of the growth of lactic acid bacteria and a cessation of fermentation.

The amount of non-lactose carbohydrate to be added to the milk base depends on a number of parameters including the lactic acid bacteria strains used in the starter, the composition of the milk base, the fermentation temperature and the desired target pH. The amount of non-lactose carbohydrate to be added to the milk base can be determined experimentally and it is within the skill of a qualified person to conduct such an experiment.

In a specific embodiment of the invention, the target pH is from 3.2 to 4.8, more preferably from 3.6 to 4.6, more preferably from 3.8 to 4.5 and most preferably from 4.0 to 4.4.

In a particular embodiment of the invention, the fermentation temperature is from 35°C to 45°C, preferably from 37°C to 43°C and most preferably from 40°C to 43°C.

In a specific embodiment of the invention, the fermented milk product is not subjected to a cooling stage after the end of the fermentation stage and before packaging.

In a specific embodiment of the invention, the fermented milk product is packaged at a temperature of 15 to 45°C.

In a specific embodiment of the invention, the amount of added non-lactose carbohydrate is from 1 mg/g to 30 mg/g, preferably from 2 mg/g to 20 mg/g and more preferably from 3 mg/g to 10 mg/g of milk base.

In a particular embodiment of the invention, the amount of added non-lactose carbohydrate is from 0.1% to 10%, preferably from 0.2% to 8%, preferably from 0.3% to 2%, preferably from 0.4% to 1.5% and most preferably from 0.5% to 1.2%, where % is (w/w) based on milk basis.

In a preferred embodiment of the invention, the milk base at the beginning of the fermentation stage has a lactose content of from 30.0 mg/ml to 70 mg/ml, preferably from 35 mg/ml to 65 mg/ml, more preferably from 40 mg/ml to 60 mg/ml and most preferably from 50 mg/ml to 60 mg/ml.

In a specific embodiment of the invention, the pH value of the fermented milk product is maintained within 0.5 pH units during storage for at least 7 days after the end of fermentation at a temperature above 10°C.

In a specific embodiment of the invention, the pH value of the fermented milk product is maintained within 0.5 pH units, preferably within 0.4 pH units, preferably within 0.3 pH units, preferably within 0.2 pH units and most preferably within 0.1 pH units when stored for at least 7 days after fermentation has ceased at a temperature above 10°C.

In a specific embodiment of the invention, the pH value of the fermented milk product is maintained within 0.5 pH units when stored for at least 7 days after the end of fermentation at a temperature above 4°C, preferably above 6°C, preferably above 8°C, preferably above 10°C, preferably above 12°C, preferably above 14°C, preferably above 16°C, preferably above 18°C, preferably above 20°C, preferably above 22°C, preferably above 24°C, preferably above 26°C, preferably above 28°C and most preferably above 30°C.

In a specific embodiment of the invention, the pH value of the fermented milk product is maintained within 0.5 pH units, preferably within 0.4 pH units, preferably within 0.3 pH units, preferably within 0.2 pH units and most preferably within 0.1 pH units when stored for at least 7 days after termination of fermentation at a temperature above 4°C, preferably above 6°C, preferably above 8°C, preferably above 10°C, preferably above 12°C, preferably above 14°C, preferably above 16°C, preferably above 18°C, preferably above 20°C, preferably above 22°C, preferably above 24°C, preferably above 26°C, preferably above 28°C and most preferably above 30°C.

The probiotic strain can be added to this process at any point during the fermentation stage, including (1) at the beginning of fermentation, (2) during fermentation, and (3) at the end of fermentation.

In a specific embodiment, the probiotic strain is added to the milk base at the beginning of fermentation. In an alternative specific embodiment, the probiotic strain is added to the milk base during fermentation. In another alternative specific embodiment, the probiotic strain is added to the fermented milk product at the end of fermentation.

In a particular embodiment of the invention, the probiotic strain is added in an inoculation dose of at least 1.0 exp06 CFU/g, preferably at least 1.0 exp07 CFU/g, more preferably at least 1.0 exp08 CFU/g.

In a particular embodiment of the invention, the probiotic strain is the Lactobacillus rhamnosus LGG® strain deposited as ATCC53103, and the probiotic strain is added at an inoculation dose of at least 1.0 exp06 CFU/g, preferably at least 1.0 exp07 CFU/g, more preferably at least 1.0 exp08 CFU/g.

Surprisingly, it was found that the higher the inoculation dose of the probiotic strain,

- 4 048587 for example LGG®, the less subsequent acidification is observed during the storage period, for example for 56 days at an ambient temperature, for example at 25°C. In particular, when using an inoculation dose of LGG® of 1.0 exp08 CFU/g, subsequent acidification can be completely avoided.

In a specific embodiment of the invention, the amount of added non-lactose carbohydrate is from 1 mg/g to 30 mg/g, preferably from 2 mg/g to 20 mg/g and more preferably from 3 mg/g to 10 mg/g of milk base.

In a particular embodiment of the invention, the amount of added non-lactose carbohydrate is from 0.1% to 10%, preferably from 0.2% to 8%, preferably from 0.3% to 2%, preferably from 0.4% to 1.5% and more preferably from 0.5% to 1.2%, where % is (w/w) based on milk basis.

In a specific embodiment, a sweetener is added to the process to produce a sweetened product. The sweetener may be added to the process at any point in the fermentation stage, including (1) at the beginning of fermentation, (2) during fermentation, and (3) at the end of fermentation.

In a preferred embodiment of the invention, the dairy substrate used for fermentation using a starter contains a sweetener. Preferably, the sweetener is selected from the group consisting of artificial sugar; high intensity sweetener; and sugar syrup, puree, juice and nectar obtained from a source selected from the group consisting of fruits, vegetables and grains. Preferably, the sugar syrup is selected from the group consisting of maple syrup, corn syrup, glucose syrup, high fructose corn syrup and golden syrup.

In the context of the present invention, the term sweetener means a natural saccharide selected from the group consisting of fructose, glucose, sucrose and mixtures thereof, artificial sugar or a high intensity sweetener.

Preferably, the high intensity sweetener is a steviol glycoside, including stevia. Preferably, the artificial sugar is a high intensity artificial sweetener selected from the group consisting of aspartame, sucralose, neotame, acesulfame potassium, saccharin, advantame and cyclamates.

Most fermented milk products available on the market contain added sweetener, such as sugar syrup or fruit puree. The advantage of adding sweetener together with the other ingredients of the milk base is that an additional, separate step of adding sweetener can be avoided. In addition, when sweetener is added to the fermented milk product after the fermentation stage, the sweetener must be heat treated or sterilized, and in addition, it must be added to the fermented milk product at an aseptic stage, which is expensive and difficult to perform. Therefore, adding sweetener before the fermentation stage is preferred.

In a particular embodiment of the invention, the sweetener is sucrose. In a particular embodiment of the invention, sucrose is added in an amount of 2% (w/w) to 12% (w/w), preferably 4% (w/w) to 11% (w/w), more preferably 5% (w/w) to 10% (w/w), more preferably 6% (w/w) to 9% (w/w), and most preferably 7% (w/w) to 8% (w/w).

In a preferred embodiment of the invention, the milk base at the beginning of the fermentation stage contains from 30.0 mg/ml to 70 mg/ml, preferably from 35 mg/ml to 65 mg/ml, more preferably from 40 mg/ml to 60 mg/ml and most preferably from 50 mg/ml to 60 mg/ml lactose.

Fermented milk product.

The present invention also relates to a fermented milk product obtained by the method according to the invention.

In a specific embodiment of the invention, the fermented milk product is a product that can be obtained using a starter culture of a strain of lactic acid bacteria containing at least one lactose-deficient strain of Streptococcus thermophilus and at least one lactose-deficient strain of Lactobacillus delbrueckii subsp. bulgaricus.

In a specific embodiment of the invention, the fermented milk product is selected from the group consisting of yogurt, cream cheese, sour milk, fermented cream, buttermilk, fermented whey, fermented milk, sour cream, kefir, drinking yogurt and yakult. Preferably, the yogurt is selected from the group consisting of thermostatically produced yogurt, broken-curd yogurt and drinking yogurt.

In a preferred embodiment of the invention, the fermented milk product contains an additional food product selected from the group consisting of a fruit drink, cereal products, fermented cereal products, chemically acidified cereal products, soy milk products, fermented soy milk products and any mixture thereof.

Fermented milk product usually contains protein in the amount of 2.0% by weight to 3.5% by weight. Fermented milk product can also be a low-protein product with a protein level of 1.0% by weight

- 5 048587 up to 2.0% by weight. Alternatively, the fermented milk product may be a high-protein product with a protein content above 3.5% by weight.

Application of the invention

The present invention also relates to use in a method for producing a fermented milk product, comprising the following stages:

1) adding to the milk base a starter culture of lactic acid bacteria containing at least one lactose-deficient strain of Streptococcus thermophilus that is capable of metabolizing a non-lactose carbohydrate and at least one lactose-deficient strain of Lactobacillus delbrueckii subsp. bulgaricus that is capable of metabolizing a non-lactose carbohydrate,

2) fermentation of the milk base for a certain period of time until the target pH is reached, producing a fermented milk product, and

3) adding a probiotic strain selected from the group consisting of a Lactobacillus strain and a Bifidobacterium strain to the process of a composition containing

1) a starter culture of lactic acid bacteria containing at least one lactose-deficient strain of Streptococcus thermophilus that is capable of metabolizing a non-lactose carbohydrate, and at least one lactose-deficient strain of Lactobacillus delbrueckii subsp. bulgaricus that is capable of metabolizing a non-lactose carbohydrate, and

2) a probiotic strain selected from the group consisting of a Lactobacillus strain and a Bifidobacterium strain.

A specific embodiment of the invention relates to the use for reducing subsequent acidification of a fermented milk product during storage after fermentation has ceased, compared to using a corresponding starter culture without a probiotic strain.

A specific embodiment of the invention relates to the use for maintaining the pH value of a fermented milk product within 0.5 pH units, during storage after fermentation has ceased for a period of at least 7 days at a temperature above 10°C.

Definitions

In the context of the present invention, the following definitions apply.

The term lactic acid bacteria (LAB) refers to Gram-positive, microaerophilic or anaerobic bacteria that ferment sugars to produce acids, including lactic acid as the predominant acid produced, acetic acid, and propionic acid. The most industrially useful lactic acid bacteria are members of the order Lactobacillales, which includes Lactococcus spp., Streptococcus spp., Lactobacillus spp., Leuconostoc spp., Pseudoleuconostoc spp., Pediococcus spp., Brevibacterium spp., Enterococcus spp., and Propionibacterium spp. They are often used as food cultures alone or in combination with other lactic acid bacteria.

Lactic acid bacteria, including bacteria of the species Lactobacillus sp. and Lactococcus sp., are commonly supplied to the dairy industry either as frozen or freeze-dried cultures for mass propagation of the starter, or as so-called direct seed cultures (DVS) intended for direct inoculation into a fermentation vessel or tank for the production of a dairy product such as a cultured milk product or cheese. Such lactic acid bacterial cultures are commonly referred to as starter cultures or cultures. Typically, the starter culture for yoghurt contains Streptococcus thermophilus and Lactobacillus delbrueckii subsp. bulgaricus, and in most countries yoghurt is legally defined as a fermented milk product produced using a starter culture containing these two strains.

The expression starter culture includes both a starter culture in the form of a mixture of all three strains of the composition, i.e. the lactose-deficient strain of Streptococcus thermophilus, the lactose-deficient strain of Lactobacillus delbrueckii subsp. bulgaricus and the probiotic strain, as well as a starter culture containing a mixture of two strains of Streptococcus thermophilus and Lactobacillus delbrueckii subsp. bulgaricus, where the probiotic strain is in a separate form allowing this probiotic strain to be added to the process independently of the addition of the other two strains.

The term milk shall be understood to mean the lactiferous secretion obtained by milking any mammal, such as cows, sheep, goats, buffalo or camels. In a preferred embodiment, the milk is cow's milk. The term milk also includes protein-fat solutions made from plant materials, such as soy milk.

The term dairy base may be any raw and/or processed dairy material that can be fermented according to the method of the invention. Thus, useful dairy bases include, but are not limited to, solutions/suspensions of any milk or milk-like products containing protein, such as whole or reduced fat milk, skim milk, buttermilk, reconstituted dry milk, condensed milk, dry milk, whey, whey permeate, lactose, mother liquor from lactose crystallization, whey protein concentrate or cream. It is obvious that the dairy base may be derived from any mammal, for example being essentially pure

- 6 048587 mammalian milk or reconstituted milk powder.

Prior to fermentation, the milk base may be homogenized and pasteurized according to methods known in the art.

The term homogenization as used here means vigorous mixing to produce a soluble suspension or emulsion. If homogenization is carried out before fermentation, it can be done in such a way as to break the milk fat into smaller fragments so that it no longer separates from the milk. This can be achieved by forcing the milk under high pressure through small holes.

Pasteurization as used here means the treatment of the milk base to reduce or eliminate the presence of living organisms such as microorganisms. Preferably, pasteurization is accomplished by maintaining a specified temperature for a specified period of time. The specified temperature is usually achieved by heating. The temperature and duration may be selected to kill or inactivate specific bacteria, such as dangerous bacteria. This may be followed by rapid cooling.

Fermentation in the methods of the present invention means the conversion of carbohydrates into alcohols or acids by microorganisms. Preferably, fermentation in the methods of the invention includes the conversion of lactose into lactic acid.

Fermentation processes used in the production of dairy products are well known, and it is clear to a person skilled in the art how to select suitable conditions, such as temperature, oxygen, the amount and characteristics of the microorganism(s), and the process time. It is obvious that the fermentation conditions are selected in such a way as to ensure the implementation of the present invention, i.e. to obtain a dairy product in solid (such as cheese) or liquid form (such as a fermented milk product).

The expression fermented milk product means a food or feed product where the preparation of the food or feed product involves the fermentation of a milk base by lactic acid bacteria. Fermented milk product as used herein includes, but is not limited to, products such as thermophilic fermented milk products such as yoghurt, mesophilic fermented milk products such as sour cream and buttermilk, and fermented whey.

The term thermophilic herein refers to microorganisms that grow best at temperatures above 35°C. The most commercially useful thermophilic bacteria include Streptococcus spp. and Lactobacillus spp. The term thermophilic fermentation herein refers to fermentation at temperatures above about 35°C, such as from about 35°C to about 45°C. The term thermophilic fermented milk product refers to fermented milk products obtained by thermophilic fermentation of a thermophilic starter culture and includes fermented milk products such as thermostatic yoghurt, broken-curd yoghurt and drinking yoghurt such as Yakult.

The term mesophilic here refers to microorganisms that grow best at moderate temperatures (15°C-35°C). The most industrially useful mesophilic bacteria include Lactococcus spp. and Leuconostoc spp. The term mesophilic fermentation here refers to fermentation at temperatures between about 22°C and about 35°C. The term mesophilic fermented milk product refers to fermented milk products obtained by mesophilic fermentation of a mesophilic starter and includes fermented milk products such as buttermilk, sour milk, cultured milk, sour cream, sour heavy cream, heavy cream, cultured cream, ymer, fermented whey, kefir, yakult and young cheese such as quark, cottage cheese and cream cheese.

The term non-lactose carbohydrate means any carbohydrate that is not lactose and that is capable of being metabolized by the lactic acid bacteria used in the method of the invention.

The term non-lactose carbohydrate depletion means that the concentration of non-lactose carbohydrate is zero or so low that the starter culture is no longer able to grow.

The expression early in the fermentation stage means shortly before, at the same time or shortly after the addition of the starter culture to the milk base. Here the term soon means less than 30 min.

The expression during the fermentation stage means at any time during fermentation after the start and until the end of fermentation.

The expression at the end of the fermentation stage means shortly before, at the same time or shortly after the target pH is reached. Here the term shortly means less than 30 min.

The term target pH means the pH at which the fermentation stage ends. Depending on various process parameters, the fermentation stage is terminated by a method selected from the group consisting of 1) acidification of the fermented milk product, which makes at least one starter strain incapable of growth, 2) cooling, and 3) depletion of non-lactose carbohydrate.

In the present context, the term mutant strain is to be understood as strains derived from, or strains obtainable from, the strain (or their parent strain) according to the invention by means of, for example, genetic engineering, radiation and/or chemical treatment. Strains derived from them may also be spontaneously occurring mutants. Preferably

- 7 048587 It is important that the strains derived therefrom are functionally equivalent to the mutants, for example mutants that have substantially the same or improved properties as their parent strain. In particular, the term mutant strains refers to strains obtained by subjecting a strain of the invention to any conventionally used mutagenizing treatment, including treatment with a chemical mutagen such as ethane methanesulfonate (EMS) or N-methyl-N'-nitro-Knitroguanidine (NTG), ultraviolet light, or to a spontaneously occurring mutant. A mutant may be subjected to several mutagenizing treatments (by one treatment it should be understood one mutagenization step followed by a screening/selection step), but it is currently preferred that not more than 20, or not more than 10, or not more than 5 treatments (or screening/selection steps) are carried out. In a currently preferred mutant, less than 1%, less than 0.1%, less than 0.01%, less than 0.001%, or even less than 0.0001% of the nucleotides in the bacterial genome have been replaced by a different nucleotide or have been deleted compared to the parent strain.

Deposits and expert decisions

The applicant requests that a sample of the deposited microorganism be provided only to an expert approved by the applicant.

The strain Streptococcus thermophilus was deposited in DSMZ - Deutsche Sammlung von Mikroorganismen und Zellkulturen GmbH, Inhoffenstr. 7B, D-38124 Braunschweig, 2014-06-12 with the registration number DSM 28952.

The strain Streptococcus thermophilus was deposited in DSMZ - Deutsche Sammlung von Mikroorganismen und Zellkulturen GmbH, Inhoffenstr. 7B, D-38124 Braunschweig, 2014-06-12 with the registration number DSM 28953.

The strain Streptococcus thermophilus was deposited in DSMZ - Deutsche Sammlung von Mikroorganismen und Zellkulturen GmbH, Inhoffenstr. 7B, D-38124 Braunschweig, 2017-08-22 with the registration number DSM 32599.

The strain Streptococcus thermophilus was deposited in DSMZ - Deutsche Sammlung von Mikroorganismen und Zellkulturen GmbH, Inhoffenstr. 7B, D-38124 Braunschweig, 2017-08-22 with the registration number DSM 32600.

The strain Lactobacillus delbrueckii subsp. bulgaricus was deposited in the DSMZ - Deutsche Sammlung von Mikroorganismen und Zellkulturen GmbH, Inhoffenstr. 7B, D-38124 Braunschweig, 2014-06-12 with the registration number DSM 28910.

The strain Bifidobacterium animalis subsp. lactis strain BB-12 was deposited with DSMZ - Deutsche Sammlung von Mikroorganismen und Zellkulturen GmbH, Mascheroder Weg. 1b, D-38124 Braunschweig, 2003-09-30 with the registration number DSM 15954.

The deposit was made in accordance with the Budapest Treaty on the International Recognition of the Deposit of Microorganisms for the Purposes of Patent Procedure.

Examples

Example 1.

Subsequent acidification of yoghurt at elevated temperatures using lactose-deficient and lactose-positive cultures in combination with probiotics.

The aim of the present experiment is to compare the effect of adding probiotic cultures LGG and BB-12 on subsequent acidification during long-term storage at room temperature for lactose-deficient cultures according to the invention and a comparative lactose-positive culture.

Starter cultures

Acidifix: Lactose-deficient culture containing lactose-deficient strains of Streptococcus thermophilus and lactose-deficient strains of Lactobacillus delbrueckii subsp. bulgaricus. The marketed strain is YoFlex Acidifix 1.0 from Chr. Hansen A/S.

Premium: A commercially available lactose-positive culture containing lactose-deficient strains of Streptococcus thermophilus and lactose-positive strains of Lactobacillus delbrueckii subsp. bulgaricus. The commercially available strain is YoFlex Premium 1.0 from Chr. Hansen A/S.

Probiotic cultures

LGG: Lactobacillus rhamnosus strain LGG®, deposited as ATCC53103

BB-12: Bifidobacterium animalis subsp. lactis strain BB-12, deposited as DSM 15954.

- 8 048587

Compositions of cultures

Table 1

Sucrose (%) Acidifix Ref. 0.75% Acidifix Ref. with sucrose up to 7.00% Acidifix Ref. with sucrose after 7.00% Acidifix LGG 0.75% Acidifix LGG with sucrose up to 7.00% Acidifix LGG with sucrose after 7.00% Acidifx BB-12 0.75% Acidifix BB-12 sucrose to 7.00% Acidifix BB-12 sucrose after 7.00% Premium Ref. 0% Premium Ref. with sucrose up to 7.00% Premium Ref. with sucrose after 7.00% Premium LGG 0% Premium LGG with sucrose up to 7.00% Premium LGG with sucrose after 7.00%

Dairy bases

Table 2

Composition of milk bases

Quantity Protein Carbohydrate Fat 3.5% milk 2550.0 g 3.8% 4.7% 3.5% Water 450 g 0,0% 0,0% 0,0% Sucrose 225 g 0,0% 100.0% 0,0% Milk base 7% sucrose up to 3225 g 3.00% 10.70% 2.75% 3.5% milk 2650 g 3.8% 4.7% 3.5% Water 380 g 0,0% 0,0% 0,0% Sucrose * 22.9 g 0,0% 100.0% 0,0% Milk base 7% sucrose after (0.75% sucrose added before 3053 g 3.30% 4.84% 3.02% 3.5% milk 2650 g 3.8% 4.7% 3.5% Water 400 g 0,0% 0,0% 0,0% Sucrose * 0 g 0,0% 100.0% 0,0% Milk base for Premium (sucrose free) 3050 g 3.30% 4.09% 3.02%

* add 100 g of sucrose solution (66%) per 1 liter of fermented milk product Method

The milk was fermented in 3 L fermenter vessels at 43°C until a final pH of 4.55 was reached, yielding yoghurt. The yoghurt was then cooled in a post-treatment unit (PTU) at 25°C and 2 bar (2-105 Pa) and transferred to 100 ml dishes, which were stored

- 9 048587 at 25°C. For each yoghurt with 0.75% sucrose added before fermentation, both samples without sugar added after fermentation and samples with sugar added after fermentation were stored (until a total of 7% sucrose was reached).

Measurements

The time to reach final pH, subsequent acidification and cell counts for the probiotic strains were measured.

Results

Table 3

Time to reach final Ph

Sucrose in milk base (%) pH at the end of fermentation Time to reach final pH Time abbreviation (hours (h) and minutes (m)) Acidifix Ref. 0.75% 4.55 6 h 30 min Acidifix Ref. with sucrose up to 7.00% 4.55 4 h 50 min 1 hour 40 minutes vs. low sucrose Acidifix LGG 0.75% 4.55 5 h 30 min 1 hour vs. no LGG Acidifix LGG with sucrose up to 7.00% 4.55 4 h 30 min 20 min vs. no LGG. 1 h vs. low sucrose. Acidifx BB-12 0.75% 4.54 6 h 00 min 30 min compared to no VV-12 Acidifix BB12 sucrose to 7.00% 4.55 4 h 30 min 20 min compared to no BB-12. 1 h 30 min compared to low sucrose. Premium Ref. 0% 4.54 5 h 30 min Premium Ref. with sucrose up to 7.00% 4.53 5 h 00 min 30 min compared to no sucrose Premium LGG 0% 4.55 5 h 15 min 15 min vs no LGG Premium LGG with sucrose up to 7.00% 4.55 4 h 45 min 15 min vs. no LGG. 30 min vs. no sucrose.

From Table 3 it follows

For Acidifix (low sucrose), LGG and BB-12 reduced the fermentation time by 1 h and 30 min, respectively.

For Acidifix (7% sucrose), both LGG and BB-12 reduced the fermentation time by 20 min.

For Premium (no sucrose) LGG reduced the fermentation time by 15 min.

For Premium (7% sucrose), LGG reduced the fermentation time by 15 min.

In conclusion, it should be noted that for the Acidifix culture, LGG reduces the fermentation time significantly more than LGG reduces the fermentation time for the Premium culture.

- 10 048587

Subsequent acidification

Table 4

Sucrose (%) pH, 7 days, 25°C Acidifix Ref. 0.75% 4.37 Acidifix Ref. with sucrose up to 7.00% 4.34 Acidifix Ref. with sucrose after 7.00% 4.34 Acidifix LGG 0.75% 4.27 Acidifix LGG with sucrose up to 7.00% 4.16 Acidifix LGG with sucrose after 7.00% 4.20 Acidifx BB-12 0.75% 4.38 Acidifix BB-12 sucrose to 7.00% 4.35 Acidifix BB-12 sucrose after 7.00% 4.36 Premium Ref. 0% 4.29 Premium Ref. with sucrose up to 7.00% 4.19 Premium Ref. with sucrose after 7.00% 4.26 Premium LGG 0% 4.00 Premium LGG with sucrose up to 7.00% 3.96 Premium LGG with sucrose after 7.00% 3.99

Table 5

The pH difference on the 7th day, 25°C between Acidfix Premium Reference culture and culture with sucrose BEFORE 0,03 0,10 Reference culture and culture with sucrose after 0,03 0,03 Reference culture and LGG culture 0,10 0.29 Reference culture and culture BB-12 +0.01 ND Reference culture sucrose before and culture LGG sucrose before 0.18 0.23 Reference culture sucrose after and culture LGG sucrose after 0.14 0.27 Reference culture sucrose before and culture BB-12 sucrose before +0.01 ND Reference culture sucrose after and culture BB-12 sucrose after +0.02 ND

As can be seen from Table 5, the effect of adding LGG on subsequent acidification is significantly less for the Acidifx culture than for the Premium culture on the 7th day at 25°C. In addition, for the combination of the Acidifx culture and BB-12, adding BB-12 has no effect on subsequent acidification at all.

Also, for the combination of Acidifix and LGG, the effect of adding sucrose before fermentation is only slightly higher than when adding sucrose after fermentation, and this effect is lower than for the combination of Premium and LGG. This shows that with the combination of Acidifix and LGG, it is actually possible to add sucrose in very excessive amounts before fermentation and still maintain an acceptably low level of subsequent acidification during storage. This is also true for the combination of Acidifix and BB-12.

- 11 048587

Number of probiotic cells

Table 6

LGG (CFU/ml) BB-12 (CFU/ml) Acidifix LGG 2,5E08 Acidifix LGG with sucrose up to 2,7E08 Acidifix LGG with sucrose after 1,8E08 Acidifx BB-12 1,6E07 Acidifix BB-12 sucrose to 1,8E07 Acidifix BB-12 sucrose after 1,ZE07 Premium LGG 3,6E08 Premium LGG with sucrose up to 3,ZE08 Premium LGG with sucrose after 1,9E08

Example 2.

Subsequent acidification of yoghurt using lactose-deficient and lactose-positive cultures in combination with probiotics.

The aim of the present experiment is to compare the effect of adding the probiotic culture LGG on subsequent acidification during long-term storage at refrigeration temperature and room temperature for a lactose-deficient culture according to the invention and a comparative lactose-positive culture.

Milk base

Table 7 ___________________Composition of the milk base___________________

Quantity Protein Carbohydrate Fat Sucrose 3.5% milk 3500 g 3.4% 4.7% 3.5% Water 200 g 0,0% 0,0% 0,0% Sucrose 278 g 0,0% 100.0% 0,0% Milk base 7% sucrose 3978 g 2.99% 11.12% 3.08% 6.99%

Starter cultures

Acidifix: Lactose-deficient culture containing lactose-deficient strains of Streptococcus thermophilus and lactose-deficient strains of Lactobacillus delbrueckii subsp. bulgaricus. The marketed strain is YoFlex Acidifix 1.0 from Chr. Hansen A/S.

Premium: A commercially available lactose-positive culture containing lactose-deficient strains of Streptococcus thermophilus and lactose-positive strains of Lactobacillus delbrueckii subsp. bulgaricus. The commercially available strain is YoFlex Premium 1.0 from Chr. Hansen A/S.

Probiotic cultures

LGG: Lactobacillus rhamnosus strain LGG®, deposited as ATCC53103.

Compositions of Culture

The milk was fermented in 3-litre fermenter vessels at 43°C until a final pH of 4.55 was reached, producing yoghurt. The yoghurt was then cooled in a post-treatment unit (PTU) at 4°C and 2 bar and transferred to 120 ml cups, which were stored at 4°C and 25°C.

- 12 048587

Measurements

Subsequent acidification and cell counts for probiotic strains were measured.

Results

Subsequent acidification

Table 9

pH on day 14, at 4°C pH on day 14, at 21 °C Acidfix 4.52 4.15 Premium 4.36 4.02 Acidifix + LGG 4.49 4.15 Premium + LGG 4.08 3.97

Table 10

The pH difference between pH on day 14, at 4°C pH on day 14, at 21 °C Acidifix and Acidifix +LGG 0,03 0,00 Premium and Premium + LGG 0.28 0,05

As can be seen from Table 10, the effect of adding LGG on subsequent acidification is significantly less for the Acidifix culture than for the Premium culture at both 4°C and 21°C.

Number of probiotic cells

Table 11

LGG (KOE/r) 14 days, 4°C LGG (KOE/r) 14 days, 21°C Acidifix + LGG 2,3E07 2,6E08 Premium + LGG 2,7E07 2,7E08

Example 3.

Subsequent acidification of yoghurt at elevated temperature using lactose-deficient cultures in combination with probiotics in different inoculation doses.

The aim of this experiment is to compare the effect of adding different inoculation doses of the probiotic culture LGG on subsequent acidification during long-term storage at room temperature for lactose-deficient cultures according to the invention.

Table 12

Milk base composition

Quantity (g) Proteins (%) Carbohydrates (%) Fats (%) Sucrose 3.4% milk 11910 z,o 4.6 3.4% Water 0,0 0,0 oh,oh oh,oh Sucrose 90 0,0 100 oh,oh Milk base 0.75% sucrose 12000 2.98 4.56 3.37 0.75%

Starter cultures

Acidifix: Lactose-deficient culture containing lactose-deficient strains of Streptococcus thermophilus and lactose-deficient strains of Lactobacillus delbrueckii subsp. bulgaricus. The marketed strain is YoFlex Acidifix 1.0 from Chr. Hansen A/S.

Probiotic cultures

LGG: Lactobacillus rhamnosus strain LGG®, deposited as ATCC53103

- 13 048587

Compositions of Culture

Table 13

Acidfix

Aci difix + LGG (1000 CFU/g)

Acidifix + LGG (10exp07 KOE/r)

Acidifix + LGG (10exp08 KOE/r)

Method

The milk fermentation was carried out in 1 l SCHOTT blue cap bottles at 43°C. When the sucrose in the sample with Acidifix and without LGG was consumed (pH 4.39), the fermentation of all samples was stopped. The bottles were shaken to break up the curd and then stored at 4°C for cooling. The following day, the yoghurt samples were aseptically transferred to 120 ml dishes, which were stored at 25°C for 56 days.

Measurements

Subsequent acidification and cell counts of probiotic strains were measured.

Results

Subsequent acidification

Table 14

pH Acidifix Acidifix + LGG (UehrOb CFU/g) Acidifix + LGG(10exp07 CFU/g) Acidifix + LGG(10exp08 KOE/r) 1 Day 4.39 4.39 4.38 4.34 7 Days 4.41 4.16 4.19 4.32 14 Days 4.41 4.17 4.20 4.43 21 Days 4.42 4.19 4.22 4.43 28 Days 4.43 4.20 4.26 4.44 35 Days 4.44 4.23 4.27 4.47 42 Days 4.41 4.21 4.25 4.42 49 Days 4.41 4.19 4.26 4.39 56 Days 4.43 4.20 4.27 4.35

Number of probiotic cells

Table 15

LGG cell count (CFU/g) Acidfix Acidifix + LGG (UehrOb CFU/g) Acidifix + LGG (Yeхр07 CFU/g) Acidifix + LGG (Yeхр08 CFU/g) 0 Days Oh, ... I,OΟΟΕΟό 8,30E06 9,70E07 1 Day 0,00E00 1,60E06 1,35E07 1,39E08 7 Days Oh, ... 4.29E08 3,44E08 4,30E08 14 Days Oh, ... 5,70E08 5,05E08 8.75E08 21 Days Oh, ... 5,70E08 6,15E08 5,55E08 28 Days Oh, ... 4,45E08 4.35E08 3,80E08 35 Days Oh, ... 6,20E07 1,29E08 1.78E08 42 Days Oh, ... 5,85E07 1,04E08 1,68E08 49 Days Oh, ... 6.05E07 1,72E08 2,11E08 56 Days Oh, ... 7,75E07 1,69E08 1,70E08

- 14048587

As can be seen from Table 15, the LGG culture level is maintained at a high level during the entire storage period of 56 days at 25°C. In addition, as can be seen from Table 14, the higher the inoculation dose of LGG, the less subsequent acidification is observed during the storage period of 56 days. In particular, when using the inoculation dose of LGG 1.0exp08 CFU/g, subsequent acidification is completely avoided.

Claims (3)

1. A composition for producing a fermented milk product containing 1) a starter culture of lactic acid bacteria comprising at least one strain of Streptococcus thermophilus with a deficiency in lactose metabolism that is capable of metabolizing a non-lactose carbohydrate, and at least one strain of Lactobacillus delbrueckii subsp. bulgaricus with a deficiency in lactose metabolism that is capable of metabolizing a non-lactose carbohydrate, and 2) a probiotic strain selected from the group consisting of a Lactobacillus rhamnosus strain and a Bifidobacterium strain, wherein the pH value of the fermented milk product is maintained within 0.5 pH units during storage for at least 7 days after the cessation of fermentation at a temperature above 10°C. 2. The composition according to claim 1, wherein the non-lactose carbohydrate is selected from the group consisting of sucrose, galactose and glucose. 3. The composition according to claim 1 or 2, wherein the strain of Streptococcus thermophilus with a deficiency in lactose metabolism is selected from the group consisting of (a) (1) strain DSM 28952; (2) a strain derived from DSM 28952, which is further characterized by the ability to form white colonies on a medium containing lactose and X-Gal (5-bromo-4-chloro-3-indolyl-beta-D-galactopyranoside); (b) (1) strain DSM 28953; (2) a strain derived from DSM 28953, which is further characterized by the ability to form white colonies on a medium containing lactose and X-Gal; (c) (1) strain DSM 32599; (2) a strain derived from DSM 32599, which is further characterized by the ability to form white colonies on a medium containing lactose and X-Gal; and (d) (1) a strain from DSM 32600; and (2) a strain derived from DSM 32600, which is further characterized by the ability to form white colonies on a medium containing lactose and X-Gal. 4. The composition according to any one of claims 1 to 3, wherein the strain of Lactobacillus delbrueckii subsp. bulgaricus with a deficiency in lactose metabolism is selected from the group consisting of (1) strain DSM 28910; and (2) a strain derived from DSM 28910, which is further characterized by the ability to form white colonies on a medium containing lactose and X-Gal. 5. The composition according to any one of claims 1 to 4, wherein the probiotic strain is the strain Lactobacillus rhamnosus LGG, deposited as ATCC53103. 6. The composition according to any one of claims 1 to 5, wherein the probiotic strain of Bifidobacterium is selected from the group consisting of Bifidobacterium longum, Bifidobacterium adolescentis, Bifidobacterium bifidum, Bifidobacterium breve, Bifidobacterium animalis subsp. lactis, Bifidobacterium dentium, Bifidobacterium catenulatum, Bifidobacterium angulatum, Bifidobacterium magnum, Bifidobacterium pseudocatenulatum and Bifidobacterium infantis. 7. The composition of claim 6, wherein the probiotic strain of Bifidobacterium is Bifidobacterium animalis subsp. lactis BB-12, deposited as DSM15954. 8. A method for producing a fermented milk product, including the following stages: 1) adding to the milk base a starter culture of lactic acid bacteria containing at least one strain of Streptococcus thermophilus with a deficiency in lactose metabolism that is capable of metabolizing a non-lactose carbohydrate, and at least one strain of Lactobacillus delbrueckii subsp. bulgaricus with a deficiency in lactose metabolism that is capable of metabolizing a non-lactose carbohydrate, 2) fermentation of the milk base for a certain period of time until the target pH is reached, producing a fermented milk product, and 3) adding a probiotic strain selected from the group consisting of a Lactobacillus rhamnosus strain and a Bifidobacterium strain to this process, wherein the pH value of the fermented milk product is maintained within 0.5 pH units during storage for at least 7 days after the cessation of fermentation at a temperature above 10°C. 9. The method according to claim 8, wherein the probiotic strain is added to the milk base at the beginning of fermentation. 10. The method according to claim 8 or 9, wherein the non-lactose carbohydrate is selected from the group consisting of sucrose, galac- - 15 048587 toses and glucose. 11. The method according to any one of claims 8 to 10, wherein the non-lactose carbohydrate is added to the milk base at the beginning of the fermentation stage. 12. The method of claim 11, wherein the non-lactose carbohydrate is added to the milk base in an amount measured such that it is depleted at the target pH, which results in the cessation of the growth of lactic acid bacteria and the cessation of fermentation. 13. The method according to any one of claims 8 to 12, wherein the strain of Streptococcus thermophilus with a deficiency in lactose metabolism is selected from the group consisting of (a) (1) strain DSM 28952; (2) a strain derived from DSM 28952, which additionally has the ability to form white colonies on a medium containing lactose and X-Gal; (b) (1) strain DSM 28953; (2) a strain derived from DSM 28953, which additionally has the ability to form white colonies on a medium containing lactose and X-Gal; (c) (1) strain DSM 32599; (2) a strain derived from DSM 32599, which additionally has the ability to form white colonies on a medium containing lactose and X-Gal; and (d) (1) a strain from DSM 32600; and (2) a strain derived from DSM 32600, which additionally has the ability to form white colonies on a medium containing lactose and X-Gal. characterized characterized characterized characterized 14. The method according to any one of claims 8 to 13, wherein the strain of Lactobacillus delbrueckii subsp. bulgaricus with a deficiency in lactose metabolism is selected from the group consisting of (1) strain DSM 28910; and (2) a strain derived from DSM 28910, which is further characterized by the ability to form white colonies on a medium containing lactose and X-Gal. 15. The method according to any one of claims 8 to 14, wherein the probiotic strain is added in an inoculation dose of at least 1.0 exp06 CFU/g, preferably at least 1.0 exp07 CFU/g, more preferably at least 1.0 exp08 CFU/g. 16. A fermented milk product obtained by the method according to any of paragraphs 8-15, wherein the pH value of the fermented milk product is maintained within 0.5 pH units during storage for at least 7 days after the end of fermentation at a temperature above 10°C. 17. Use of the composition according to item 1 for producing a fermented milk product. 18. The use according to item 17, wherein subsequent acidification of the fermented milk product during storage after the cessation of fermentation is reduced compared to the use of the corresponding starter culture without a probiotic strain during fermentation.