阅读说明：本技术 在环境温度时稳定的新食品 (Novel food product stable at ambient temperature ) 是由 毛跃建 于 2019-07-16 设计创作，主要内容包括：本申请涉及基于用稳定的乳酸菌对食品进行接种而制造在环境温度时稳定的食品的方法,所述乳酸菌能够在环境温度时存储时保持成活力并稍微降低pH。本发明还涉及这些稳定的乳酸菌用于在食品中接种的用途。(The present application relates to a method for manufacturing a food product stable at ambient temperature based on the inoculation of the food product with a stable lactic acid bacterium capable of maintaining viability and slightly lowering the pH upon storage at ambient temperature. The invention also relates to the use of these stabilized lactic acid bacteria for inoculation in food products.)

1. A method for making a food product stable at ambient temperature, the method comprising:

1) providing a starting food product having a pH between 3.4 and 4.6, in particular a starting food product with a low bacterial content having a pH between 3.4 and 4.6, said starting food product with a low bacterial content comprising not more than 1x10²Bacterial levels of CFU/g;

2) at least 1x10 to the starting food, in particular to the starting food with low bacteria content⁵One or more stable lactic acid bacteria are added to the total amount of CFU/g to obtain a food product stable at ambient temperature,

the method is characterized in that:

(i) each of the one or more stabilized lactic acid bacteria is selected from the group consisting of: strains of the species Lactobacillus plantarum (Lactobacillus plantarum), Lactobacillus sourdough (Lactobacillus zymae), Lactobacillus rosenbergii (Lactobacillus rossiae), Lactobacillus delbrueckii (Lactobacillus collinoides), Lactobacillus similis (Lactobacillus similis), Lactobacillus fermordanii (Lactobacillus versmoldensis), Lactobacillus acidopilus (Lactobacillus acidophilus), Lactobacillus bulgaricus (Lactobacillus hammesii), Lactobacillus nomame (Lactobacillus fermentum), Lactobacillus delbrueckii (Lactobacillus nodenis) and Lactobacillus casei (Lactobacillus tuccei); and is

(ii) When the ratio is 1x10⁷Each of the one or more stabilized lactic acid bacteria when added to a test yogurt of pH 4.3 previously heat treated at 75 ℃ for 25 seconds:

a) storing the test yogurt at a temperature of 37 ℃ for 30 days at a rate of at least 5x10³The amount of CFU/g remains viable; and is

b) After 30 days of storage of the test yoghurt at a temperature of 37 ℃, the pH of the test yoghurt is lowered by at most 0.6 units.

2. The method of claim 1, wherein the molar ratio is 1x10⁷When CFU/g is added to a test yoghurt with a pH of 4.3, which has been heat treated at 75 ℃ for 25 seconds in advance, the stabilized lactic acid bacteria are stored at a temperature of 37 ℃ for 30 days and then at least 1x10⁴CFU/g, at least 5x10⁴CFU/g, at least 1x10⁵CFU/g, at least 5x10⁵CFU/g or at least 1x10⁶The amount of CFU/g remained viable.

3. The method of claim 1 or 2, wherein when expressed as 1x10⁷The amount of CFU/g when added to a test yoghurt having a pH of 4.3 which has been heat treated at 75 ℃ for 25 seconds in advance, the stabilized lactic acid bacteria reduce the pH of the test yoghurt by at most 0.5 units, at most 0.4 units, or at most 0.3 units after 30 days of storage of the test yoghurt at a temperature of 37 ℃.

4. The method according to any one of claims 1 to 3, wherein the initial food product having a pH between 3.4 and 4.6 is selected from the group consisting of: milk-based products, such as fermented milk products or chemically acidified milk products; fruit-based products, such as fruit juice or fermented fruit juice; vegetable-based products, such as vegetable juices or fermented vegetable juices; grain-based products, such as chemically acidified grain products or fermented grain products; rice-based products, such as chemically acidified or fermented rice products; nut-based products, such as chemically acidified nut products or fermented nut products; soy-based products, such as fermented soy milk products; and any mixtures thereof.

5. Process according to any one of claims 1 to 4, wherein the starting food product having a pH between 3.4 and 4.6 is a dairy food product, in particular a fermented dairy product, more particularly a yoghurt.

6. The method according to any one of claims 1 to 5, wherein the low bacteria content starting food product having a pH between 3.4 and 4.6 is a treated starting food product to obtain the following bacteria levels: not more than 1x 10²CFU/g of said low bacteria content starting food product, in particular heat-treated starting food product.

7. The method of any of claims 1 to 6, the method comprising:

1) providing a starting food product having a pH between 3.4 and 4.6;

1b) treating said starting food product so as to obtain a product not exceeding 1x10²CFU/g bacteria level of the low bacteria content starting food product, in particular by heat treatment of the starting food product; and is

2) Adding at least 1x10 of the bacteria to the low bacteria content initial food product⁵One or more stable lactic acid bacteria are added to the total amount of CFU/g to obtain a food product that is stable at ambient temperature.

8. Method according to any one of claims 1 to 7, wherein the low bacteria content starting food product is a treated or heat-treated dairy food product, in particular a treated or heat-treated fermented dairy product, more in particular a treated or heat-treated yoghurt.

9. The method according to any one of claims 1 to 8, the method comprising:

1a) producing an initial fermented milk, in particular an initial yoghurt, having a pH between 3.4 and 4.6 by fermentation of a milk base;

1b) treating, in particular heat treating, said initial fermented milk, in particular said initial yoghurt, so as to obtain an initial fermented milk with a low bacterial content, in particular an initial yoghurt with a low bacterial content, comprising a level of bacteria not exceeding 1x10²CFU/g; and is

2) At least 1x10 to the low bacteria content initial fermented milk, in particular to the low bacteria content initial yoghurt⁵One or more stable strains of lactic acid bacteria are added to the total amount of CFU/g to obtain a fermented milk, in particular a yoghurt, which is stable at ambient temperature.

10. The method according to any one of claims 1 to 9, wherein the pH of the initial food product, in particular the initial food product with a low bacterial content, is between 3.4 and 4.0, between 4.0 and 4.6 or between 3.6 and 4.2.

11. The method according to any one of claims 1 to 10, wherein the one or more stabilized lactic acid bacteria are administered at a dosage of at least 5x10⁵G, at least 1x10⁶G, at least 5x10⁶/g or at least 1x10⁷The total amount of CFU/g is added to the starting food product, in particular to the starting food product with a low bacterial content.

12. The method according to any one of claims 1 to 11, wherein the one or more stabilized lactic acid bacteria are added aseptically to the starting food product, in particular to the starting food product with a low bacterial content.

13. The method according to any one of claims 1 to 12, wherein the one or more stabilized lactic acid bacteria is a lactic acid bacterium belonging to the species Lactobacillus plantarum.

14. The method of claim 13, wherein the one or more stabilized lactic acid bacteria are selected from the group consisting of: the strain DSM32493, the variant of the strain DSM32493, deposited at DSMZ on day 26 in 2017, the strain DSM33120, the variant of the strain DSM33120, deposited at DSMZ on day 5 and 22 in 2019, the strain DSM33121, deposited at DSMZ on day 5 and 22 in 2019, and the variant of the strain DSM33121, deposited at DSMZ on day 1x10⁷The variant a) after 30 days of storage at a temperature of 37 ℃ in a test yoghurt with a pH of 4.3, previously heat-treated at 75 ℃ for 25 seconds, when CFU/g is added to the test yoghurt in an amount of at least 5x10³The amount of CFU/g remains viable; and b) after storing the test yogurt for 30 days at a temperature of 37 ℃, reducing the pH of the test yogurt by at most 0.6 units.

15. The method of claim 14, wherein the variant of DSM32493 is a DSM32493 strain in which the ATP synthase alpha subunit gene of the ATP synthase operon has a mutation from G to a at position 506 thereof.

16. The method according to any one of claims 1 to 15, wherein the food product is stable at ambient temperature after 180 days of storage at a temperature of 25 ℃:

-its pH does not decrease more than 0.7 units; and is

-it contains a stable lactic acid bacteria in an amount of at least 1x10³CFU/g, and/or no more than a 3log reduction.

17. A food product stable at ambient temperature obtained by the method of any one of claims 1 to 16.

18. Use of one or more stabilized lactic acid bacteria for inoculation in a food product having a pH of 3.4 to 4.6, in particular in a starting food product with a low bacterial content, wherein

(i) Each of the one or more stabilized lactic acid bacteria is selected from the group consisting of: strains of the species Lactobacillus plantarum, Lactobacillus sourdough, Lactobacillus rosenbergii, Lactobacillus thalamus, Lactobacillus similis, Lactobacillus fermordelbrum, Lactobacillus acidovorus, Lactobacillus bulgaricus, Lactobacillus namulus, Lactobacillus delbrueckii and Lactobacillus jejuni; and is

(ii) When the ratio is 1x10⁶Each of the one or more stabilized lactic acid bacteria when added to a test yogurt of pH 4.3 previously heat treated at 75 ℃ for 25 seconds:

a) storing the test yogurt at a temperature of 37 ℃ for 30 days at a rate of at least 5x10³The amount of CFU/g remains viable; and is

b) After 30 days of storage of the test yoghurt at a temperature of 37 ℃, the pH of the test yoghurt is lowered by at most 0.6 units.

19. A lactobacillus plantarum strain selected from the group consisting of: the strain DSM33120 deposited at DSMZ on day 5/22 in 2019, a variant of the strain DSM33120, the strain DSM33121 deposited at DSMZ on day 5/22 in 2019, and DSM33121 variants of the Strain at 1X10⁷The variant a) after 30 days of storage at a temperature of 37 ℃ in a test yoghurt with a pH of 4.3, previously heat-treated at 75 ℃ for 25 seconds, when CFU/g is added to the test yoghurt in an amount of at least 5x10³The amount of CFU/g remains viable; and b) after storing the test yogurt for 30 days at a temperature of 37 ℃, reducing the pH of the test yogurt by at most 0.6 units.

Technical Field

The present application relates to a method for manufacturing a food product stable at ambient temperature based on the inoculation of the food product with one or more stable lactic acid bacteria capable of remaining viable and slightly lowering the pH when stored at ambient temperature. The invention also relates to the use of these one or more stabilized lactic acid bacteria for inoculation in food products.

Background

In recent years, there has been a trend towards food products, in particular dairy products, containing high levels of viable bacteria (for health purposes) which can be stored at ambient temperature at the same time. Indeed, consumers are looking for healthy foods that are easy to consume, i.e. easy to transport and store. Such an environmental product would also be advantageous in countries where the cold chain is very complex during distribution and storage of food products containing high levels of viable bacteria, especially in countries where economic or technical impossibility is concerned.

Two major problems that result from storage of food products containing high levels of viable bacteria at ambient temperatures are: (1) the proliferation of live bacteria in food products leads to the production of undesirable metabolites that ultimately affect the quality of the food product (e.g., lactic acid bacteria are capable of producing lactic acid at ambient temperatures, resulting in an unacceptable pH drop of the final product (e.g., dairy product)), and then (2) the death of bacteria that cannot survive in the food matrix at ambient temperatures, resulting in the loss of benefits associated with the bacteria.

Application WO 2017/194650 describes Lactobacillus strains of Lactobacillus paracasei, Lactobacillus rhamnosus, Lactobacillus fermentum or Lactobacillus delbrueckii subspecies bulgaricus which are capable of being stored for 150 days (5 months) at 25 ℃ at a storage time of at least 10³cfu/g (starting at 2.5X 10)⁷The level of cfu/g) remained viable and did not decrease the pH of the test product by more than 0.8 units.

However, food producers are seeking ways to constantly improve the level of lactic acid bacteria (especially by reducing the level of viability compared to the level of inoculation) and ways to reduce the pH drop in food products to ensure their consumer acceptable bacterial health benefits and stable food quality, especially when the food products are stored at ambient temperature. Furthermore, in some countries, such as china, both producers and consumers require the ability to store food products at ambient temperature for at least 6 months without affecting the properties of the food product.

Thus, there remains a need to identify bacteria that when inoculated into a food product are capable of maintaining high viability and resulting in a smaller pH drop after storage of the food product under more stringent conditions at ambient temperature (at least 6 months).

Drawings

Figure 1 is a graph showing the viability (in log cfu) of 80 strains (representative of 33 lactobacillus species) in test yoghurts after 30 days of storage at 37 ℃ by assay a.

FIG. 2 is a graph showing the pH of test yoghurts inoculated with one of 80 strains (33 Lactobacillus species) by assay A after 30 days of storage at 37 ℃.

Fig. 3 is a graph showing the pH of test yoghurts inoculated with one of the 20 tested strains (grey bars) after 30 days storage at 37 ℃ by assay a, and showing the viability (in log cfu) of the 20 tested strains in the test yoghurt (black dots).

FIG. 4 is a graph showing (A) the evolution of viability of the DSM32493 strain in yoghurt (in log cfu) and (B) the evolution of the pH of yoghurt during 180 days of storage at 25 ℃.

FIG. 5 is a graph showing (A) the evolution of the viability of the DSM32493v strain in yoghurt (in log cfu) and (B) the evolution of the pH of yoghurt during 180 days of storage at 25 ℃.

FIG. 6 is a graph showing (A) the evolution of viability of the DSM33120 strain in yoghurt (in log cfu) and (B) the evolution of the pH of yoghurt during 180 days of storage at 25 ℃.

FIG. 7 is a graph showing (A) the evolution of the viability of the DSM33121 strain in yoghurt (in log cfu) and (B) the evolution of the pH of yoghurt during 180 days of storage at 25 ℃.

Detailed Description

The inventors have unexpectedly identified lactobacillus strains that can be added to food products such that the viability of these strains in the food product and the pH of the food product are both acceptably reduced when stored at ambient temperature. Thus, the food product contains high levels of bacteria and has an acceptable pH when stored at ambient temperature for at least 6 months.

The present invention relates to a method for manufacturing a food product stable at ambient temperature, the method comprising:

1) providing a starting food product having a pH between 3.4 and 4.6, in particular a starting food product with a low bacterial content having a pH between 3.4 and 4.6, said starting food product with a low bacterial content comprising not more than 1x10²CFU/g bacteria level of the low bacteria content starting food product;

2) at least 1.0x10 into the initial food product, especially into the initial food product with low bacteria content⁵One or more stable lactic acid bacteria are added to the total amount of CFU/g to obtain a food product stable at ambient temperature,

the method is characterized in that:

(i) each of the one or more stabilized lactic acid bacteria is selected from the group consisting of: strains of the species Lactobacillus plantarum (Lactobacillus plantarum), Lactobacillus sourdough (Lactobacillus zymae), Lactobacillus rosenbergii (Lactobacillus rossiae), Lactobacillus delbrueckii (Lactobacillus collinoides), Lactobacillus similis (Lactobacillus similis), Lactobacillus fermordanii (Lactobacillus versmoldensis), Lactobacillus acidopilus (Lactobacillus acidophilus), Lactobacillus bulgaricus (Lactobacillus hammesii), Lactobacillus nomame (Lactobacillus fermentum), Lactobacillus delbrueckii (Lactobacillus nodenis) and Lactobacillus casei (Lactobacillus tuccei); and is

(ii) When the speed is 1x10⁷Each of the one or more stabilized lactic acid bacteria when added to a test yogurt of pH 4.3 previously heat treated at 75 ℃ for 25 seconds:

a) storing the test yogurt at a temperature of 37 ℃ for 30 days at least 5.0x10³The amount of CFU/g remains viable; and is

b) After 30 days of storage of the test yoghurt at a temperature of 37 ℃, the pH of the test yoghurt is lowered by at most 0.6 units.

The invention also relates to the use of one or more stabilized lactic acid bacteria for inoculation in a starting food product having a pH between 3.4 and 4.6, in particular a starting food product with a low bacterial content, wherein

(i) The stable lactic acid bacteria are selected from the group consisting of: strains of the species Lactobacillus plantarum, Lactobacillus sourdough, Lactobacillus rosenbergii, Lactobacillus thalamus, Lactobacillus similis, Lactobacillus fermordelbrum, Lactobacillus acidovorus, Lactobacillus bulgaricus, Lactobacillus namulus, Lactobacillus delbrueckii and Lactobacillus jejuni; and is

(ii) When the speed is 1x10⁶The amount of CFU/g when added to a test yoghurt of pH 4.3 previously heat treated at 75 ℃ for 25 seconds, the stabilized lactic acid bacteria:

a) storing the test yogurt at a temperature of 37 ℃ for 30 days at least 5.0x10³The amount of CFU/g remains viable; and is

b) After 30 days of storage of the test yoghurt at a temperature of 37 ℃, the pH of the test yoghurt is lowered by at most 0.6 units.

Starting food product

The initial food product having a pH between 3.4 and 4.6 is provided in step 1) of the method of the invention or in the use of the invention.

By "food product" is meant any product intended for human consumption. According to the present invention (in particular step 2 of the process), the starting food product must be suitable for inoculation with one or more stable lactic acid bacteria. By "starting food product" is meant a food product prior to the addition of one or more stabilized lactic acid bacteria, and therefore which does not comprise stabilized lactic acid bacteria as defined herein. The starting food product must be distinguished from a "food product stable at ambient temperature" comprising a stabilized lactic acid bacterium as defined herein.

In an embodiment, the starting food product is a fermented food product. Fermentation is carried out by converting carbohydrates into acids by the action of bacterial fermenters. "bacterial starter" is defined as a composition comprising or consisting of: one or more bacteria capable of initiating and performing fermentation of the substrate. In a particular embodiment, the starting food product is an acetic acid fermented food product, meaning that fermentation is carried out by converting carbohydrates into acetic acid by the action of an acetobacter xylinum starter. In the examples, the starting food is a lactic acid fermented food, which means that fermentation is performed by converting carbohydrates into lactic acid by the action of a lactic acid bacteria starter. The expression "lactic acid bacteria" (LAB) relates to food grade bacteria that produce lactic acid as the main metabolic end product of carbohydrate fermentation. Lactic acid bacteria are well known in the art and include strains of Lactococcus (Lactococcus), Streptococcus (Streptococcus), Lactobacillus (Lactobacillus), Bifidobacterium (Bifidobacterium), Leuconostoc (Leuconostoc), Enterococcus (Enterococcus), Pediococcus (Pediococcus), Brevibacterium (Brevibacterium) and propionibacterium (propionibacterium).

In an embodiment, the initial food product of step 1) is selected from the group consisting of: a milk-based product, a fruit-based product (e.g., a fruit-based beverage), a vegetable-based product (e.g., a vegetable-based beverage), a grain-based product (e.g., a grain-based beverage), a rice-based product (e.g., a rice-based beverage), a nut-based product (e.g., a nut-based beverage), a soy-based product, and any mixtures thereof. By "milk-based product", "fruit-based product or beverage", "vegetable-based product or beverage", "cereal-based product or beverage", "rice-based product or beverage", "nut-based product or beverage", and "soy-based product", it is meant that the main ingredients of the initial food product are milk, fruit, vegetables, cereals, rice, nuts, and soy, respectively. In embodiments, milk, fruits, vegetables, grains, rice, nuts, and soybeans are the only ingredients used as a matrix for making milk-based products, fruit-based products or beverages, vegetable-based products or beverages, grain-based products or beverages, rice-based products or beverages, nut-based products or beverages, and soybean-based products, respectively (as a starting food). The term "beverage" is defined in this application as a liquid food.

In an embodiment, the milk-based product (as a starting food) is a fermented milk product or a chemically acidified milk product. In an embodiment, the fermented milk product is selected from the group consisting of: fermented milk, yogurt, cheese, sour cream, buttermilk, and fermented whey. Fermented milk products are well known in the art and are manufactured by the action of a lactic acid bacteria starter (as defined herein) on a milk substrate (the pH of the milk substrate is about 6.5 to 7). "milk base" is defined herein as milk of any mammalian origin, including but not limited to cow's milk, sheep's milk, and goat's milk. The milk may be in a natural state, reconstituted milk or skim milk. Milk bases, in particular milk, are usually treated beforehand, in particular by standardisation, addition of additives [ e.g. sugars, sweeteners and/or stabilisers ], homogenisation and/or heat treatment [ e.g. pasteurisation ]. In a particular embodiment, the fermented milk is obtained by fermenting milk with a lactic acid bacteria starter selected from the group consisting of: a starter culture comprising a strain of Streptococcus thermophilus, a starter culture comprising a strain from the genus lactobacillus and a starter culture comprising a strain of lactococcus lactis. In a particular embodiment, the fermented milk is obtained by fermenting milk with a lactic acid bacteria starter selected from the group consisting of: a leavening agent comprising or consisting of streptococcus thermophilus and Lactobacillus bulgaricus (Lactobacillus bulgaricus), a leavening agent comprising or consisting of streptococcus thermophilus and Lactobacillus johnsonii (Lactobacillus johnsonii) and a leavening agent comprising or consisting of streptococcus thermophilus and Lactobacillus fermentum (Lactobacillus fermentum). In a particular embodiment, the fermented milk is yogurt.

In an embodiment, the fruit-based product (as a starting food product) is a fruit-based beverage. In particular embodiments, the fruit-based product is a fruit juice or a fermented fruit juice.

In an embodiment, the vegetable-based product (as a starting food) is a vegetable-based beverage. In particular embodiments, the vegetable-based product is a vegetable juice or a fermented vegetable juice.

In an embodiment, the cereal-based product (as a starting food product) is a cereal-based beverage. In particular embodiments, the grain-based product is a chemically acidified grain product, a fermented grain product, a chemically acidified grain beverage, or a fermented grain beverage.

In the examples, the rice-based product (as a starting food) is a rice-based beverage. In particular embodiments, the rice-based product is a chemically acidified rice product, a fermented rice product, a chemically acidified rice beverage, or a fermented rice beverage.

In an embodiment, the nut-based product is a nut-based beverage. In particular embodiments, the nut-based product is a chemically acidified nut product, a fermented nut product, a chemically acidified nut drink, or a fermented nut drink. In certain embodiments of any of the nut-based products described herein, the food product is a walnut-based product.

In an embodiment, the soy-based product (as a starting food) is a soy-based beverage. In particular embodiments, the soy-based product is a fermented soy milk product.

In embodiments, the term "starting food product" also encompasses any mixture of a milk-based product, a fruit-based product or beverage, a vegetable-based product or beverage, a cereal-based product or beverage, a rice-based product or beverage, a nut-based product or beverage, and a soy-based product, as defined herein, for example, such as, but not limited to, a mixture of a milk-based product and a cereal-based beverage, or a mixture of a milk-based product and a fruit-based beverage.

In an embodiment, the starting food product is a "low bacteria content" starting food product having a pH between 3.4 and 4.6, i.e. a starting food product as defined herein, having a bacteria level of not more than 1x10²CFU/g of the low bacteria content starting food product. By "bacterial level" as used herein, it is meant the total amount of bacteria calculated as cfu/g product. cfu counts can be measured by inoculating one or more dilutions of the product to be tested on MRS/M17/PCA agar [ Atlas,2010Handbook of Microbiological Media [ Handbook of Microbiological Media 2010)]Fourth edition, pages 986,1231 and 1402]。

Any starting food product with a low bacterial content may be used in step 1) of the process of the invention or in the use of the invention. According to the invention (in particular step 2 of the process), a starting food product with a low bacterial content must be suitable for inoculation with stable bacteria.

In an embodiment, the starting food product naturally has no more than 1x10²Bacterial levels of CFU/g food.

In another embodimentIn the examples, the starting food product has more than 1x10 in addition to the stabilized lactic acid bacteria as defined herein²Bacterial levels of CFU/g food. The presence of bacteria, in particular lactic acid bacteria, may be due to the use of these microorganisms (in particular as leavening agents) during the manufacturing process of the starting food product, for example, when the starting food product is produced by fermentation of a substrate (as explained above).

Thus, in an optional embodiment of the invention, the starting food product is treated before inoculation of the stabilized LAB to obtain a starting food product with a low bacterial content. By "treatment" it is meant any treatment that inactivates the bacteria contained in the starting food product (e.g., it inhibits or reduces bacterial growth or kills bacteria) so as to reduce the level of bacteria to no more than 1x10²CFU/g food with low bacteria content. Processing means are well known in the art. In an embodiment, the starting food product is treated using a means selected from the group consisting of autoclaving, irradiation, ultrafiltration and heat treatment. In a particular embodiment, the initial food product is heat treated to reduce the level of bacteria to no more than 1x10²CFU/g food with low bacteria content.

By "heat treatment", it is meant any treatment based on temperature that inactivates the bacteria contained in the starting food product (e.g., it inhibits or reduces bacterial growth or kills bacteria) so as to reduce the bacteria level of the low bacteria content food product to no more than 1x10²CFU/g food with low bacteria content.

Thus, in an embodiment, the invention relates to a method for manufacturing a food product stable at ambient temperature, the method comprising:

1) providing a starting food product having a pH between 3.4 and 4.6;

1b) treating said starting food product so as to obtain a product of not more than 1x10²CFU/g [ resulting low bacteria content starting food product]In particular by heat treatment of the initial food product; and is

2) Adding at least 1.0x10 to the low bacteria content initial food product⁵One or more stable lactic acid bacteria are added to the total amount of CFU/g to obtain a food product stable at ambient temperature,

the method is characterized in that:

(i) each of the one or more stabilized lactic acid bacteria is selected from the group consisting of: strains of the species Lactobacillus plantarum, Lactobacillus sourdough, Lactobacillus rosenbergii, Lactobacillus thalamus, Lactobacillus similis, Lactobacillus fermordelbrum, Lactobacillus acidovorus, Lactobacillus bulgaricus, Lactobacillus namulus, Lactobacillus delbrueckii and Lactobacillus jejuni; and is

(ii) When the speed is 1x10⁷Each of the one or more stabilized lactic acid bacteria when added to a test yogurt of pH 4.3 previously heat treated at 75 ℃ for 25 seconds:

a) storing the test yogurt at a temperature of 37 ℃ for 30 days at least 5.0x10³The amount of CFU/g remains viable; and is

b) After 30 days of storage of the test yoghurt at a temperature of 37 ℃, the pH of the test yoghurt is lowered by at most 0.6 units.

In an embodiment, the method of the invention is carried out in fermented milk as defined herein, in particular yoghurt as defined herein. The present invention therefore relates to a process for the manufacture of fermented milk, in particular yoghurt, which is stable at ambient temperature, said process comprising

1a) Producing an initial fermented milk, in particular an initial yoghurt, having a pH between 3.4 and 4.6 by fermentation of a milk base;

1b) treating, in particular heat treating, said initial fermented milk, in particular said initial yoghurt, so as to obtain an initial fermented milk with a low bacterial content, in particular an initial yoghurt with a low bacterial content, comprising a level of bacteria not exceeding 1x10²CFU/g; and is

2) At least 1.0x10 into the low bacteria content initial fermented milk, in particular into the low bacteria content initial yoghurt⁵One or more stable strains of lactic acid bacteria are added to the total amount of CFU/g to obtain a fermented milk, in particular a yoghurt,

the method is characterized in that:

(i) each of the one or more stabilized lactic acid bacteria is selected from the group consisting of: strains of the species Lactobacillus plantarum, Lactobacillus sourdough, Lactobacillus rosenbergii, Lactobacillus thalamus, Lactobacillus similis, Lactobacillus fermordelbrum, Lactobacillus acidovorus, Lactobacillus bulgaricus, Lactobacillus namulus, Lactobacillus delbrueckii and Lactobacillus jejuni; and is

(ii) When the speed is 1x10⁷The amount of CFU/g, when added to a test yoghurt of pH 4.3 previously heat treated at 75 ℃ for 25 seconds, of one or more of each of said stabilized lactic acid bacteria:

a) storing the test yogurt at a temperature of 37 ℃ for 30 days at least 5.0x10³The amount of CFU/g remains viable; and is

b) After 30 days of storage of the test yoghurt at a temperature of 37 ℃, the pH of the test yoghurt is lowered by at most 0.6 units.

The initial, optionally low-bacteria-content food product [ in particular provided as such (step 1) or after treatment (step 1b) or after production by fermentation and treatment (step 1b) ], must be suitable for achieving the object of the invention, i.e. to make a food product stable at ambient temperature.

In an embodiment, the pH of the initial, optionally low bacteria content, food product is between 3.4 and 4.6. In an embodiment, the pH of the initial, optionally low bacteria content, food product is between 3.4 and 4.0. In an embodiment, the pH of the initial, optionally low bacteria content, food product is between 4.0 and 4.6. In an embodiment, the pH of the initial, optionally low bacteria content, food product is between 3.6 and 4.2. The pH can be determined by using any pH meter.

In an embodiment, optionally in combination with any of the embodiments of the above paragraph, the sugar content of the initial, optionally low bacteria content, food product is between 0% and 13%. By "sugar content" it is meant the total content of sugar (whether sugar initially contained in the initial food product, added to the initial food product or a combination of sugar initially contained in the initial food product and sugar added to the initial food product) in the initial, optionally low bacterial content, food product. In an embodiment, the sugar content of the initial optionally low bacterial content food product is between 4% and 10%. In an embodiment, the sugar content of the initial optionally low bacterial content food product is between 6% and 9%. In a particular content, the sucrose content of the initial optionally low bacterial content food product is between 0 and 8%. In an embodiment, the sucrose content of the initial optionally low bacterial content food product is between 5% and 8%.

Adding/inoculating one or more stabilized lactic acid bacteria to a starting food product

The starting food product as defined herein, in particular a starting food product with a low bacterial content as defined herein, is served at a level of at least 1.0x10⁵The total amount of CFU/g is inoculated with one or more stable lactic acid bacteria (step 2 of the process of the invention or the use of the invention).

In the context of the present invention, "adding" is used interchangeably with "inoculating" (and "added" and "inoculated") and refers to contacting one or more stabilized lactic acid bacteria (as defined herein) with the starting food product. By "one or more" is meant at least one Lactic Acid Bacterium (LAB). In an embodiment, the amount of LAB added to the food product is selected from the group consisting of: 1. 2, 3, 4, 5, 6, 7, 8, 9 and 10. In the examples, 1 kind of stabilized LAB was added to a food product. In the examples, 2 stabilized LAB were added to a food product. In the examples, 3 stabilized LAB were added to a food product. In the examples, 4 stabilized LAB were added to a food product. In the examples, 5 stabilized LAB were added to a food product.

Adding one or more stabilized LABs in a total amount of at least 1x10⁵cfu/g food product is added to the starting food product, in particular to the starting food product with a low bacterial content. When adding several (i.e. at least 2) stabilized LABs, "total amount" refers to the sum of each individual amount of seeded stabilized LAB (e.g. at 3x 10)⁵First stabilized LAB at cfu/g and 7x10⁵Addition of a second stabilized LAB of cfu/g resulted in 1x10⁶Total amount of cfu/g). In embodiments, at least one of the group consisting of 5x10⁵CFU/g, at least 1x10⁶CFU/g, at least 5x10⁶CFU/g or at least 1x10⁷Adding one or more stabilized LAB to a starting food product, in particular to a starting food product with a low bacterial contentIn the starting food. In embodiments, the compound is selected from the group consisting of 1x10⁵To 1x10⁸cfu/g、1x10⁶To 1x10⁸cfu/g and 5x10⁶To 1x10⁸The total amount of the group consisting of cfu/g range one or more stabilized LAB is added to the starting food product, in particular a starting food product with a low bacterial content.

The one or more stabilized LAB may be inoculated into the starting food product in any form, e.g. frozen, dried, lyophilized, in liquid or solid form, in pellet or frozen pellet form, or in powder or dry powder form. In an embodiment, one or more stabilized LAB are used in liquid form, e.g. as a bulk starter [ i.e. a LAB culture that has been propagated in advance in a growth medium to obtain the desired inoculation concentration]Added to the starting food. In an embodiment, the one or more stabilized LAB are added directly to the starting food product in the form of a concentrate, e.g., a frozen or dried concentrate. In an embodiment, the one or more stabilized LAB are used in liquid form as a dilution of a concentrate (e.g., a frozen or dried concentrate) [ e.g., in water or a salt solution]Can be added into food. The expression "direct inoculation" means that one or more stabilized LAB are added to the starting food product without prior propagation. Direct inoculation requires that the concentration of one or more stabilized LAB is sufficiently high. Thus, the concentration range of stabilized LAB in the frozen or dried concentrate is 10⁸To 10¹²cfu/g concentrate, and more preferably at least 10⁸At least 10⁹At least 10¹⁰At least 10¹¹Or at least 10¹²cfu/g concentrate.

In embodiments, the one or more strains are added aseptically to the starting food product. By "aseptically", it is meant that no other microorganisms than the one or more stable lactic acid bacteria are added to the food product, e.g. by using a Tetra flexdos (tm) sterile in-house inoculation system.

Stabilized lactic acid bacteria (stabilized LAB)

The one or more stabilized Lactic Acid Bacteria (LAB) added to the process as claimed in the present invention or to the starting food product in the use of the present invention (step 2) are characterized by the following 2 characteristics:

(i) the one or more stable strains of lactic acid bacteria are selected from the group consisting of: strains of the species Lactobacillus plantarum, Lactobacillus sourdough, Lactobacillus rosenbergii, Lactobacillus thalamus, Lactobacillus similis, Lactobacillus fermordelbrum, Lactobacillus acidovorus, Lactobacillus bulgaricus, Lactobacillus namulleri, Lactobacillus delbrueckii and Lactobacillus jejuni.

In embodiments, the one or more stable strains of lactic acid bacteria are selected from the group consisting of: strains of the species Lactobacillus plantarum, Lactobacillus sourdough, Lactobacillus rosenbergii, Lactobacillus thalamus, Lactobacillus fermordelbrum and Lactobacillus namulus. In embodiments, the one or more stable strains of lactic acid bacteria are selected from the group consisting of: strains of the species Lactobacillus plantarum and Lactobacillus sourdough.

In an embodiment, the one or more stable lactic acid bacterial strains are of the species lactobacillus plantarum. In an embodiment, the one or more stable lactic acid bacterial strains are of the species lactobacillus sourdough. In an embodiment, the one or more stable lactic acid bacterial strains are of the species lactobacillus rosei. In embodiments, the one or more stable lactic acid bacterial strains are of the species lactobacillus thalamus. In an embodiment, the one or more stable lactic acid bacterial strains are of the species lactobacillus sp. In an embodiment, the one or more stable lactic acid bacterial strains are of the species lactobacillus fermoreus. In an embodiment, the one or more stable lactic acid bacterial strains are lactobacillus acidophilus belonging to the species lactobacillus acidophilus. In an embodiment, the one or more stable lactic acid bacterial strains are of the species lactobacillus heisui. In an embodiment, the one or more stable lactic acid bacterial strains are of the species lactobacillus namuni. In an embodiment, the one or more stable lactic acid bacterial strains are of the species lactobacillus wildlife. In an embodiment, the one or more stable lactic acid bacterial strains are of the species lactobacillus casei.

For the avoidance of doubt, the lactobacillus species described herein are as defined in the literature, particularly in Salvetti et al 2012Probiotics & Antimicro.prot. [ Probiotics and antimicrobial proteins ]4(4): 217-.

(ii) Each of the one or more stable strains of lactic acid bacteria remained viable in heat-treated yogurt stored for 30 days at a temperature of 37 ℃ (i.e. under stringent conditions) and did not have its pH significantly reduced.

Thus, in the example, when 1x10⁷The stable lactic acid bacterial strain, when added in an amount of CFU/g to a test yoghurt with a pH of 4.3, previously heat treated at 75 ℃ for 25 seconds:

a) storing the test yogurt at a temperature of 37 ℃ for 30 days at least 5.0x10³The amount of CFU/g remains viable; and is

b) After 30 days of storage of the test yoghurt at a temperature of 37 ℃, the pH of the test yoghurt is lowered by at most 0.6 units.

In embodiments, the test yoghurt has a sugar content of 0% to 13%. In an embodiment, the test yoghurt has a sugar content of 4% to 10%. In an embodiment, the test yoghurt has a sugar content of 6% to 9%. At a specific level, the sucrose content of the test yoghurts is 0% to 8%. In an embodiment, the sucrose content of the test yoghurts is 5% to 8%. In embodiments, the test yoghurts have a sugar content of 12% to 13%, including a sucrose content of 7% to 9%.

In the examples, characteristic (ii) was tested with assay a as follows:

the inoculum of the LAB to be tested is prepared as follows: will 10⁶The LAB culture of cfu/mL was grown overnight at 37 ℃ in 10mL MRS/M17 liquid medium; after 2 hours at 4 ℃, the culture was centrifuged at 4000rpm for 10 minutes; resuspend the pellet in 10mL sterile saline; repeating the centrifugation/resuspension step again to obtain the inoculum

After inoculation at about 1X10⁹After CFU/mL normalization, 0.4mL of inoculum was added to 40mL of heat-treated yogurt (2.8% protein, 3% fat, 12.5% total sugars (including 8% sucrose); pH 4.3) and mixed well[ Final stabilized LAB concentration in Heat-treated yogurt about 1X10⁷CFU/g yoghourt](ii) a The tube is then sealed.

-incubating the inoculated yoghurt for 30 days at 37 ℃.

After 30 days, the pH was determined by means of a pH meter (Mettler Toledo, SevenEasy); the pH at day 30 was then compared to the pH of the heat-treated yogurt when LAB was added

After 30 days, CFU counts were determined by plating on MRS/M17 agar as follows: 1mL of yogurt sample was serially diluted to 10 with sterile saline^-7(ii) a MRS/M17 agar (1.5%) was melted and kept at 48 ℃ in a water bath; 1mL of 10^-1To 10^-7The dilution was added to a petri dish and 25mL of MRS/M17 agar was poured in; plates were incubated anaerobically at 37 ℃ for 2 days to count; the LAB amount at day 30 was then compared to the LAB amount added to the heat treated yogurt.

In the embodiment of feature a), when 1 × 10⁷When CFU/g is added to a test yoghurt of pH 4.3, which has been heat treated for 25 seconds at 75 ℃, the stabilized lactic acid bacteria strain (e.g. by application assay A) is stored at a temperature of 37 ℃ for 30 days and then at least 5x10³CFU/g, at least 1x10⁴CFU/g, at least 5x10⁴CFU/g, at least 1x10⁵CFU/g, at least 5x10⁵CFU/g or at least 1x10⁶The amount of CFU/g remained viable.

In the embodiment of feature b), considered alone or in combination with the preceding embodiment [ feature a ]]Combined, when considering as 1x10⁷When added to a test yogurt with a pH of 4.3 that has been heat treated at 75 ℃ for 25 seconds in advance, the stabilized lactic acid bacterial strain (e.g. by applying assay a) reduces the pH of the test yogurt by at most 0.6 units, at most 0.5 units, at most 0.4 units or at most 0.3 units after storage of the test yogurt for 30 days at a temperature of 37 ℃.

In the example, when 1x10⁷The stable lactic acid bacterial strain (e.g. by applying assay a) when added in an amount of CFU/g to a test yoghurt with a pH of 4.3 previously heat treated at 75 ℃ for 25 seconds:

a) to be provided withAn amount selected from the group consisting of: at least 5.0x10³CFU/g, at least 1.0x10⁴CFU/g, at least 5.0x10⁴CFU/g, at least 1.0x10⁵CFU/g, at least 5.0x10⁵CFU/g or at least 1.0x10⁶CFU/g; and is

b) Reducing the pH of the test yogurt by at most 0.6 units, at most 0.5 units, at most 0.4 units, or at most 0.3 units,

this is after 30 days of storage of the test yoghurt at a temperature of 37 ℃.

In a particular embodiment, when 1x10⁷The stable lactic acid bacterial strain (e.g. by applying assay a) when added in an amount of CFU/g to a test yoghurt with a pH of 4.3 previously heat treated at 75 ℃ for 25 seconds:

a) maintaining viability in an amount selected from the group consisting of: at least 1x10⁴CFU/g, at least 5x10⁴CFU/g, at least 1x10⁵CFU/g, at least 5x10⁵CFU/g or at least 1x10⁶CFU/g; and is

b) Reducing the pH of the test yogurt by at most 0.6 units, at most 0.5 units, at most 0.4 units, or at most 0.3 units,

this is after 30 days of storage of the test yoghurt at a temperature of 37 ℃.

In a particular embodiment, when 1x10⁷The stable lactic acid bacterial strain (e.g. by applying assay a) when added in an amount of CFU/g to a test yoghurt with a pH of 4.3 previously heat treated at 75 ℃ for 25 seconds:

a) maintaining viability in an amount selected from the group consisting of: at least 5x10³CFU/g, at least 1x10⁴CFU/g, at least 5x10⁴CFU/g, at least 1x10⁵CFU/g, at least 5x10⁵CFU/g or at least 1.0x10⁶CFU/g; and is

b) Reducing the pH of the test yogurt by at most 0.5 units, at most 0.4 units, or at most 0.3 units,

this is after 30 days of storage of the test yoghurt at a temperature of 37 ℃.

In a particular embodiment, whenAt 1x10⁷The stable lactic acid bacterial strain (e.g. by applying assay a) when added in an amount of CFU/g to a test yoghurt with a pH of 4.3 previously heat treated at 75 ℃ for 25 seconds:

a) maintaining viability in an amount selected from the group consisting of: at least 1x10⁴CFU/g, at least 5x10⁴CFU/g, at least 1x10⁵CFU/g, at least 5x10⁵CFU/g or at least 1x10⁶CFU/g; and is

b) Reducing the pH of the test yogurt by at most 0.5 units, at most 0.4 units, or at most 0.3 units,

this is after 30 days of storage of the test yoghurt at a temperature of 37 ℃.

In a particular embodiment, when 1x10⁷The stable lactic acid bacterial strain (e.g. by applying assay a) when added in an amount of CFU/g to a test yoghurt with a pH of 4.3 previously heat treated at 75 ℃ for 25 seconds:

a) maintaining viability in an amount selected from the group consisting of: at least 1x10⁵CFU/g, at least 5x10⁵CFU/g or at least 1x10⁶CFU/g; and is

b) The pH of the test yoghurt was lowered by at most 0.3 units,

this is after 30 days of storage of the test yoghurt at a temperature of 37 ℃.

Any strain of lactobacillus plantarum, lactobacillus sourdough, lactobacillus rosenbergii, lactobacillus thalamus, similar lactobacillus, lactobacillus fermordelbrueckii, lactobacillus sauvigus, lactobacillus heimeri, lactobacillus namullerii, lactobacillus wilderni and lactobacillus sausage that fulfils the characteristic (ii) as defined herein, in particular when assessed by test a, can be used in the method of the invention or in the use of the invention.

In embodiments, the stable lactic acid bacterial strain is selected from the group consisting of: the species Lactobacillus plantarum, Lactobacillus sourdough, Lactobacillus roseilkii, Lactobacillus thalamus, Lactobacillus similis, Lactobacillus fermordelbrum, Lactobacillus acidovorus, Lactobacillus bulgaricus, Lactobacillus nomurae, Lactobacillus delbrueckii and Lactobacillus jejuni, and, when expressed at 1X10, the strains⁷Amount of CFU/g added to pHThe stable lactic acid bacterial strain (e.g. by applying assay a) when in a test yoghurt of 4.3 previously heat treated at 75 ℃ for 25 seconds:

a) maintaining viability in an amount selected from the group consisting of: at least 5x10³CFU/g, at least 1x10⁴CFU/g, at least 5x10⁴CFU/g, at least 1x10⁵CFU/g, at least 5.0x10⁵CFU/g or at least 1x10⁶CFU/g; and is

b) Reducing the pH of the test yogurt by at most 0.6 units, at most 0.5 units, at most 0.4 units, or at most 0.3 units,

this is after 30 days of storage of the test yoghurt at a temperature of 37 ℃.

In embodiments, the stable lactic acid bacterial strain is selected from the group consisting of: the species Lactobacillus plantarum, Lactobacillus sourdough, Lactobacillus rosei, Lactobacillus thalamus, Lactobacillus fermoratus, Lactobacillus buehensis, similar strains of Lactobacillus, Lactobacillus delbrueckii, Lactobacillus jejuni and Lactobacillus namulus, and when expressed as 1X10⁷The stable lactic acid bacterial strain (e.g. by applying assay a) when added in an amount of CFU/g to a test yoghurt with a pH of 4.3 previously heat treated at 75 ℃ for 25 seconds:

a) maintaining viability in an amount selected from the group consisting of: at least 1x10⁴CFU/g, at least 5x10⁴CFU/g, at least 1x10⁵CFU/g, at least 5x10⁵CFU/g or at least 1x10⁶CFU/g; and is

b) Reducing the pH of the test yogurt by at most 0.6 units, at most 0.5 units, at most 0.4 units, or at most 0.3 units,

this is after 30 days of storage of the test yoghurt at a temperature of 37 ℃.

In embodiments, the stable lactic acid bacterial strain is selected from the group consisting of: strains of the species Lactobacillus plantarum, Lactobacillus sourdough, Lactobacillus rosenbergii, Lactobacillus thalamus, Lactobacillus fermordelbrum, Lactobacillus similis and Lactobacillus namulus, and when expressed at 1X10⁷The amount of CFU/g was added to a test yoghurt of pH 4.3, previously heat treated at 75 ℃ for 25 secondsIn (e), the stable lactic acid bacterial strain (e.g. by applying assay a):

a) maintaining viability in an amount selected from the group consisting of: at least 5x10³CFU/g, at least 1x10⁴CFU/g, at least 5x10⁴CFU/g, at least 1x10⁵CFU/g, at least 5x10⁵CFU/g or at least 1x10⁶CFU/g; and is

b) Reducing the pH of the test yogurt by at most 0.5 units, at most 0.4 units, or at most 0.3 units,

this is after 30 days of storage of the test yoghurt at a temperature of 37 ℃.

In embodiments, the stable lactic acid bacterial strain is selected from the group consisting of: strains of the species Lactobacillus plantarum, Lactobacillus sourdough, Lactobacillus rosenbergii, Lactobacillus thalamus, Lactobacillus fermordelbrum, Lactobacillus similis and Lactobacillus namulus, and when expressed at 1X10⁷The stable lactic acid bacterial strain (e.g. by applying assay a) when added in an amount of CFU/g to a test yoghurt with a pH of 4.3 previously heat treated at 75 ℃ for 25 seconds:

a) maintaining viability in an amount selected from the group consisting of: at least 1x10⁴CFU/g, at least 5x10⁴CFU/g, at least 1x10⁵CFU/g, at least 5x10⁵CFU/g or at least 1x10⁶CFU/g; and is

b) Reducing the pH of the test yogurt by at most 0.5 units, at most 0.4 units, or at most 0.3 units,

this is after 30 days of storage of the test yoghurt at a temperature of 37 ℃.

In embodiments, the stable lactic acid bacterial strain is selected from the group consisting of: strains of the species Lactobacillus plantarum and Lactobacillus sourdough, and, when expressed at 1X10⁷The stable lactic acid bacterial strain (e.g. by applying assay a) when added in an amount of CFU/g to a test yoghurt with a pH of 4.3 previously heat treated at 75 ℃ for 25 seconds:

a) maintaining viability in an amount selected from the group consisting of: at least 1x10⁵CFU/g, at least 5x10⁵CFU/g or at least 1x10⁶CFU(ii)/g; and is

b) The pH of the test yoghurt was lowered by at most 0.3 units,

this is after 30 days of storage of the test yoghurt at a temperature of 37 ℃.

In the examples, the stable lactic acid bacterial strain is a lactobacillus plantarum belonging to the species lactobacillus plantarum and, when expressed at 1x10⁷The stable lactic acid bacterial strain (e.g. by applying assay a) when added in an amount of CFU/g to a test yoghurt with a pH of 4.3 previously heat treated at 75 ℃ for 25 seconds:

a) maintaining viability in an amount selected from the group consisting of: at least 1x10⁵CFU/g, at least 5x10⁵CFU/g or at least 1x10⁶CFU/g; and is

b) The pH of the test yoghurt was lowered by at most 0.3 units,

this is after 30 days of storage of the test yoghurt at a temperature of 37 ℃.

In an embodiment, the one or more stabilized LAB to be added to step 2) of the inventive process or used in the inventive use is selected from the group consisting of: lactobacillus plantarum strain DSM32493, variants of strain DSM32493, deposited at DSMZ on day 26, 2017, strain DSM33120, deposited at DSMZ on day 5, 22, 2019, strain DSM33121, deposited at DSMZ on day 5, 22, 2019, and variants of strain DSM33121, deposited at DSMZ on day 22, DSM 33121.

In an embodiment, the one or more stabilized LAB to be added to step 2) of the method of the invention or used in the use of the invention is lactobacillus plantarum strain DSM32493, or a variant of DSM32493 strain, deposited at DSMZ on day 26, 4 months 2017.

In an embodiment, the one or more stable lactic acid bacteria to be added to step 2) of the method of the invention or used in the use of the invention is a variant of lactobacillus plantarum strain DSM32493 deposited at DSMZ on day 26/4 of 2017, wherein the variant has a mutation (e.g., a point mutation, deletion, insertion,..) in the ATP synthase alpha subunit gene (compared to the DSM32493 strain). The wild-type sequence of the ATP synthase operon is as shown in SEQ ID NO 1. Those skilled in the art know how to determine whether the operon is outburstVariation, and how to measure H of bacteria⁺-atpase activity [ see, e.g., Jaichumjai et al, 2010; food Microbiology]27(2010)741-748]. In embodiments, the one or more stable lactic acid bacteria is a variant of DSM32493, wherein the variant has at least one mutation in an ATP synthase alpha subunit gene of an ATP synthase operon (referred to herein as an "ATP synthase alpha subunit gene"). In particular embodiments, the one or more stable lactic acid bacteria is a variant of DSM32493, wherein the ATP synthase alpha subunit gene of the variant of DSM32493 as defined herein encodes an ATP synthase alpha subunit protein having an aspartate residue at position 169. In a particular embodiment, the one or more stable lactic acid bacteria is a variant of DSM32493, wherein the variant has at least one mutation in an ATP synthase alpha subunit gene of the ATP synthase operon defined in SEQ ID No. 2. In particular embodiments, in combination or not in combination with the previous embodiments for SEQ ID No. 2, the one or more stable lactic acid bacteria is a variant of DSM32493 as defined herein, wherein the variant has a mutation from G to a at position 506 of the ATP synthase alpha subunit gene (compared to the DSM32493 strain). In a specific embodiment, the one or more stable lactic acid bacteria is a variant of DSM32493 as defined herein, wherein the ATP synthase alpha subunit gene of said variant is as defined in SEQ ID NO:4 (wherein the codons GGT are changed to GAT at positions 505-. In a particular embodiment, the one or more stable lactic acid bacteria to be added in step 2) of the method of the invention is a variant of DSM32493, wherein the ATP synthase alpha subunit gene of said variant of DSM32493 as defined herein encodes an ATP synthase alpha subunit protein as defined in SEQ ID No. 5.

In an embodiment, the one or more stabilized LAB to be added to step 2) of the method of the invention or used in the use of the invention is lactobacillus plantarum strain DSM33120, deposited at DSMZ on day 5, 22 in 2019, or a variant of DSM33120 strain.

In an embodiment, the one or more stabilized LAB to be added to step 2) of the method of the invention or used in the use of the invention is lactobacillus plantarum strain DSM33121, or a variant of DSM33121 strain, deposited at the DSMZ on day 5, 22 of 2019.

Lactobacillus plantarum strains

The invention also relates to a lactobacillus plantarum strain selected from the group consisting of: strain DSM33120 as defined herein, deposited at DSMZ on day 5/22 of 2019, a variant of strain DSM33120 as defined herein, strain DSM33121 as deposited at DSMZ on day 5/22 of 2019, and a variant of strain DSM33121 as defined herein.

In an embodiment, the invention relates to a lactobacillus plantarum strain selected from the group consisting of: strain DSM33120 as deposited at DSMZ on day 5/22 in 2019, or a variant of strain DSM33120 as defined herein. In an embodiment, the invention relates to a lactobacillus plantarum strain selected from the group consisting of: strain DSM33121 as deposited at DSMZ on day 5/22 of 2019, or a variant of strain DSM33121 as defined herein.

Bacterial compositions

The invention also relates to a bacterial composition comprising or consisting of: a lactobacillus plantarum strain selected from the group consisting of: strain DSM33120 as defined herein, deposited at DSMZ on day 5/22 of 2019, a variant of strain DSM33120 as defined herein, strain DSM33121 as deposited at DSMZ on day 5/22 of 2019, and a variant of strain DSM33121 as defined herein.

In a particular embodiment, the bacterial composition is a pure culture, i.e. comprises or consists of: a single strain of lactobacillus plantarum of the invention. In another embodiment, the bacterial composition is a mixed culture, i.e. comprises or consists of: the lactobacillus plantarum strain of the invention and at least one other bacterial strain, in particular one other lactic acid bacterium.

In embodiments, the bacterial composition (whether as a pure culture or a mixed culture as defined above) further comprises a food-acceptable ingredient.

In particular embodiments, the bacterial composition in the form of a pure culture or a mixed culture as defined above is in frozen, dried, freeze-dried, liquid or solid form, in the form of pellets or frozen pellets, or in the form of a powder or dry powder. In particular embodiments, the bacterial composition of the invention is in frozen form or in the form of pellets or frozen pellets, in particular contained in one or more boxes or sachets. In another embodiment, the bacterial composition as defined herein is in powder form, such as a dried or freeze-dried powder, in particular contained in one or more boxes or sachets.

In a particular embodiment, the bacterial composition of the invention, whether as a pure culture or mixed culture as defined above, and whether in whatever form (frozen, dried, freeze-dried, liquid or solid form, in the form of pellets or frozen pellets, or in the form of a powder or dry powder), comprises the lactobacillus plantarum strain of the invention, at a concentration range comprised between 10⁵To 10¹²cfu (colony forming units)/gram of bacterial composition. In a particular embodiment, the concentration of the lactobacillus plantarum strain in the bacterial composition of the invention ranges from 10⁷To 10¹²cfu/gram of bacterial composition, and in particular at least 10⁷At least 10⁸At least 10⁹At least 10¹⁰Or at least 10¹¹CFU/g bacterial composition. In a particular embodiment, the concentration of the lactobacillus plantarum strain of the invention (as pure culture or as mixed culture) within the bacterial composition ranges from 10 when in the form of a frozen or dried concentrate⁸To 10¹²cfu/g frozen or dried concentrate, and more preferably at least 10⁸At least 10⁹At least 10¹⁰At least 10¹¹Or at least 10¹²cfu/g frozen concentrate or dried concentrate.

Variants of Lactobacillus plantarum strains

The features detailed herein for the variants of the deposited lactobacillus plantarum strain apply to the lactobacillus plantarum strain added within the method of the invention, to the lactobacillus plantarum strain as such and to the lactobacillus plantarum strain as part of the bacterial composition.

A variant of the strain DSM32493, DSM33120 or DSM33121 is defined herein as a strain of lactobacillus plantarum which exhibits at least one mutation, such as an addition, deletion, insertion and/or substitution of at least one nucleotide in its genome, compared to the strain DSM32493, DSM33120 or DSM33121, respectively. In particular embodiments, the variant has a genomic sequence that is at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, at least 99.1%, at least 99.2%, at least 99.3%, at least 99.4%, at least 99.5%, at least 99.6%, at least 99.7%, at least 99.8%, at least 99.9%, at least 99.92%, at least 99.94%, at least 99.96%, at least 99.98%, or at least 99.99% identical to the genomic sequence of strain DSM32493, DSM33120, or DSM33121, respectively. Such variants may be, for example:

-a native variant spontaneously obtained from strain DSM32493, DSM33120 or DSM33121 after incubation in a selection medium. Thus, the natural variants are obtained without any genetic manipulation, but only by spontaneous mutation of the strain and selection of the strain in an appropriate medium; examples of protocols for selecting specific mutants of strain DSM32493, DSM33120 or DSM33121 are disclosed in example 5; or

-variants comprising at least one mutation in their genome, said mutation being induced by genetic engineering, for example by site-directed mutagenesis or random mutagenesis. Random mutagenesis can be performed with UV radiation or mutagenic compounds such as nitrous acid, ethyl methanesulfonate, N-methyl-N' -nitro-N-nitrosoguanidine, N-ethyl-N-nitrosourea, acridine orange, proflavine.

In the example, when 1x10⁷The variant of strain DSM32493, DSM33120 or DSM33121 (as defined herein) when added to a test yoghurt having a pH of 4.3 previously heat treated at 75 ℃ for 25 seconds (e.g. by application assay a):

a) maintaining viability in an amount selected from the group consisting of: at least 5x10³CFU/g, at least 1x10⁴CFU/g, at least 5x10⁴CFU/g, at least 1x10⁵CFU/g, at least 5x10⁵CFU/g or at least 1x.10⁶CFU/g; and is

b) Reducing the pH of the test yogurt by at most 0.6 units, at most 0.5 units, at most 0.4 units, or at most 0.3 units,

this is after 30 days of storage of the test yoghurt at a temperature of 37 ℃.

In the example, when 1x10⁷The variant of strain DSM32493, DSM33120 or DSM33121 (as defined herein) when added to a test yoghurt having a pH of 4.3 previously heat treated at 75 ℃ for 25 seconds (e.g. by application assay a):

a) maintaining viability in an amount selected from the group consisting of: at least 5x10³CFU/g, at least 1x10⁴CFU/g, at least 5x10⁴CFU/g, at least 1x10⁵CFU/g, at least 5x10⁵CFU/g or at least 1x10⁶CFU/g; and is

b) Reducing the pH of the test yogurt by at most 0.5 units, at most 0.4 units, or at most 0.3 units,

this is after 30 days of storage of the test yoghurt at a temperature of 37 ℃.

In an embodiment, the variant of DSM32493, DSM33120 or DSM33121 strain (as defined herein) retains at least the same viability and at most the same pH reduction (when measured at 1x 10) as DSM32493, DSM33120 or DSM33121 strain, respectively⁷The amount of CFU/g when added to a test yoghurt with a pH of 4.3 which has been heat treated at 75 ℃ for 25 seconds, e.g. by application assay a), i.e. the described variant of DSM32493, DSM33120 or DSM33121 strain:

a) retains the same viability as that of the strain DSM32493, DSM33120 or DSM33121, respectively, or retains a higher viability (calculated as cfu/g) than that of the strain DSM32493, DSM33120 or DSM 33121; and is

b) The pH of the test yoghurts was reduced the same as the pH of the strain DSM32493, DSM33120 or DSM33121, respectively, or less than the pH of the strain DSM32493, DSM33120 or DSM33121, respectively (calculated in pH units).

Food product stable at ambient temperature

The purpose of the method is to produce a food product that is stable at ambient temperature. The expression "stable at ambient temperature" when referring to a food product refers to a food product containing one or more stabilized lactic acid bacteria as defined herein and which has not been significantly reduced in both the amount and the pH of the stabilized lactic acid bacteria when stored at ambient temperature.

Thus, the food product produced by the method of the invention is considered stable when stored at a temperature of 25 ℃ for 180 days:

-its pH does not decrease more than 0.7 units; and is

-it contains a stable lactic acid bacteria with a reduction of no more than 3log and/or said amount is at least 1x10³CFU/g。

Thus, from the day (day 0) when one or more stabilized lactic acid bacteria as defined herein are added to the starting food product, the food product is stored for 180 days at 25 ℃. In an embodiment, the food product is stored in a sealed form (i.e., in a closed, sterile container).

After 180 days, the pH was measured by a pH meter (mettler toledo, SevenEasy) and compared with the pH of the food on day 0. Thus, in embodiments, the pH of the food product decreases by no more than 0.6 units, no more than 0.5 units, or no more than 0.4 units at 180 days (as compared to the pH at day 0).

After 180 days, the CFU count is determined as described in assay a detailed herein and compared to the amount of one or more stable lactic acid bacteria as defined herein added on day 0. Thus, in embodiments, whatever the level of addition in step 2) (which is at least 1x 10)⁵CFU) comprising one or more stable lactic acid bacteria in an amount of at least 1x10³CFU/g (compared to the amount added on day 0). In embodiments, it comprises no more than a 3log reduction in the amount of one or more stabilized lactic acid bacteria (compared to the amount added on day 0). In embodiments, it comprises no more than a 2log reduction in the amount of one or more stabilized lactic acid bacteria (compared to the amount added on day 0). In embodiments, it comprises one or more stable lactic acid bacteria in an amount that is not reduced by more than 3log, and the amount is at least 1x10³CFU/g (compared to the amount added on day 0). In embodiments, it comprises one or more stable lactic acid bacteria in an amount that is not reduced by more than 2log, and the amount is at least 1x10³CFU/g (compared to the amount added on day 0).

The present invention also relates to a food product stable at ambient temperature, as defined herein or as obtained by the process of the present invention, and comprising one or more stabilized lactic acid bacteria as defined herein.

In embodiments, the food product stable at ambient temperature (which is as defined herein or as obtained by the method of the invention) comprises a lactobacillus plantarum strain selected from the group consisting of: strain DSM33120 as defined herein, deposited at DSMZ on day 5/22 of 2019, a variant of strain DSM33120 as defined herein, strain DSM33121 as deposited at DSMZ on day 5/22 of 2019, and a variant of strain DSM33121 as defined herein.

In embodiments, the food product stable at ambient temperature (which is as defined herein or as obtained by the method of the invention) comprises a lactobacillus plantarum strain selected from the group consisting of: strain DSM33120 as deposited at DSMZ on day 5/22 in 2019, or a variant of strain DSM33120 as defined herein. In embodiments, the food product stable at ambient temperature (which is as defined herein or as obtained by the method of the invention) comprises a lactobacillus plantarum strain selected from the group consisting of: strain DSM33121 as deposited at DSMZ on day 5/22 of 2019, or a variant of strain DSM33121 as defined herein.

In an embodiment, the food product stable at ambient temperature of the invention (as such or obtained by the method of the invention) has a reduced pH of no more than 0.7 units and has an amount of stabilized lactic acid bacteria it contains. Does not decrease by more than 3log and/or by at least 1x10 after 180 days of storage at a temperature of 25 ℃³CFU/g。

In an embodiment, the ambient temperature stable food product of the invention (as such or obtained by the process of the invention) is selected from the group consisting of: a milk-based food product, a fruit-based food product (e.g., a fruit-based food beverage), a vegetable-based food product (e.g., a vegetable-based food beverage), a grain-based food product (e.g., a grain-based food beverage), a rice-based food product (e.g., a rice-based food beverage), a nut-based food product (e.g., a nut-based food beverage), a soy-based food product, and any mixtures thereof. In embodiments, the milk-based food product that is stable at ambient temperature is a fermented dairy product or a chemically acidified dairy product. In an embodiment, the fermented milk product is selected from the group consisting of: fermented milk, yogurt, cheese, sour cream, buttermilk, and fermented whey. In an embodiment, the milk-based food product is fermented milk.

In embodiments, the ambient temperature stable food product of the invention (in particular a fermented milk food product as defined herein) comprises one or more of said stable lactic acid bacteria selected from the group consisting of: strains of the species Lactobacillus plantarum, Lactobacillus sourdough, Lactobacillus rosenbergii, Lactobacillus thalamus, Lactobacillus similis, Lactobacillus fermordelbrum, Lactobacillus acidovorus, Lactobacillus bulgaricus, Lactobacillus namulus, Lactobacillus delbrueckii and Lactobacillus jejuni, when written at 1X10⁷The amount of CFU/g, when added to a test yoghurt of pH 4.3 previously heat treated at 75 ℃ for 25 seconds, of one or more of each of said stabilized lactic acid bacteria: a) storing the test yogurt at a temperature of 37 ℃ for 30 days at least 5.0x10³The amount of CFU/g remains viable; and b) after storing the test yogurt for 30 days at a temperature of 37 ℃, reducing the pH of the test yogurt by at most 0.6 units. In particular embodiments, the one or more stable strains of lactic acid bacteria are selected from the group consisting of: strains of the species Lactobacillus plantarum, Lactobacillus sourdough, Lactobacillus rosenbergii, Lactobacillus thalamus, Lactobacillus fermordelbrum and Lactobacillus namulus. In particular embodiments, the one or more stable strains of lactic acid bacteria are selected from the group consisting of: strains of the species Lactobacillus plantarum and Lactobacillus sourdough. In a particular embodiment, the one or more stable lactic acid bacterial strains is the species lactobacillus plantarum. In a particular embodiment, the one or more stable lactic acid bacterial strains is the DSM32493 strain deposited at DSMZ on day 26/4 2017 or any variant thereof as defined herein.

The definitions and specific examples detailed for the manufacturing method of the invention apply analogously in the context of the food product of the invention stable at ambient temperature, in particular but not limited to the lactic acid bacteria species, the number of lactic acid bacteria, the pH lowering profile after 180 days of storage of LAB at a temperature of 25 ℃, the LAB viability retention profile after 180 days of storage of LAB at a temperature of 25 ℃, any combination of such pH lowering and LAB viability retention profiles, the food type (e.g. beverage) and the food property (e.g. milk based food product, fruit based food product, vegetable based food product, cereal based food product, rice based food product, nut based food product, soy based food product and any mixture thereof).

Preservation and professional solutions

The following deposits were made under the budapest treaty on the international recognition of the deposit of microorganisms for the purposes of patent procedure.

Lactobacillus plantarum strain DGCC12411, deposited at accession number DSM32493 on 26.4.2017 by DuPont Nutrition Biosciences ApS at DSMZ [ Deutsche Sammlung von Mikroorganismen und Zellkulturen GmbH, Deutsche, Delelix, Enghaofengda street No. 7B, zip code D-38124(Inhoffenstrasse 7B, D-38124Braunschweig-Germany) ];

lactobacillus plantarum strain DGCC12119 deposited at DSMZ under accession number DSM33120 by du pont nutrition biosciences, 5 months 22, 2019; and is

Lactobacillus plantarum strain DGCC12480 deposited at DSMZ under accession number DSM33121 by dupont nutrition biosciences, 5, 22, 2019.

The biological material is required to be provided only by samples issued to experts specified by the requester. For those designations seeking protection of european patents, a sample of the deposited microorganism is available before the publication granted to european patent or before the date the application is refused or withdrawn, or deemed withdrawn, and the issuance of this sample is limited to an expert designated by the applicant requesting the acquisition of the sample, and, optionally, solicits i) applicant and/or ii) approval from the european patent office (article 32 of the european patent convention).

Sequence of

SEQ ID NO 1 Lactobacillus plantarum ATP synthase operon

2 ATP synthase alpha subunit gene of strain DSM32493

3 ATP synthase alpha subunit protein of strain DSM32493

Variant ATP synthase alpha subunit gene of strain DSM32493 SEQ ID NO 4

5 ATP synthase alpha subunit protein of variants of strain DSM32493

Various preferred features and embodiments of the invention will now be described by way of non-limiting example.

Examples of the invention

Example 1: screening for Stable lactic acid bacteria (species)

Stable lactic acid bacteria were selected using assay a as follows:

inoculum preparation

Each LAB to be tested was prepared as follows: will 10⁶The LAB culture of cfu/mL was grown overnight at 37 ℃ in 10mL MRS/M17 liquid medium; after 2 hours at 4 ℃, the culture was centrifuged at 4000rpm for 10 minutes; resuspend the pellet in 10mL sterile saline; the centrifugation/resuspension step was repeated again. Inocula at about 1x10⁹The amount of CFU/ml was normalized. The lactobacillus species listed in table 1 were tested.

Testing yogurt

Yoghurt with the following characteristics-2.8% protein, 3% fat, 12.5% total sugar (including 8% sucrose); pH 4.3-Heat treatment to reduce bacterial levels to less than 1X10²CFU/g。

Addition/inoculation

0.4mL of the prepared inoculum was added to 40mL of heat-treated yogurt (in a tube) and mixed well. The tube is then sealed. The concentration of stabilized LAB added to heat treated yogurt (day 0) was about 1x10⁷CFU/g yoghurt.

Storing

The sealed tubes were then stored at 37 ℃ for 30 days. These conditions are considered to represent an accelerated storage model at ambient temperature.

On day 30, the pH and the amount of stabilized LAB (cell count) were determined and the difference from the pH and the amount of added stabilized LAB on day 0, respectively, was calculated.

pH and cell count measurements

The pH was measured by a pH meter (SevenEasy, Toledo, Mettler).

CFU counts were determined by plating on MRS/M17 agar as follows: 1mL yogurt samples (day 30) were serially diluted to 10 with sterile saline^-7(ii) a MRS/M17 agar (1.5%) was melted and kept at 48 ℃ in a water bath; 1mL of 10^-1To 10^-7The dilution was added to a petri dish and 25mL of MRS/M17 agar was poured in; plates were incubated anaerobically at 37 ℃ for 2 days for counting.

Selecting

Selecting a stable LAB takes into account the following two characteristics:

-at least 5x10³cfu(3.69log₁₀Amount of LAB of cfu); and is

-a decrease in pH of at most 0.6 units (i.e. a pH of at least 3.7).

Results

80 strains representing 33 species were tested and selected by assay A. The strain levels (cfu) in the yoghurt after 30 days storage at 37 ℃ and the pH of the yoghurt are summarized in Table 1 and shown in FIG. 1(log cfu) and FIG. 2 (pH).

TABLE 1: log cfu and pH obtained by measuring a after storage at 37 ℃ for 30 days by using a strain of 33 species of lactobacillus; STD: standard deviation; n.a.: not applicable to

As shown in table 1 and fig. 1 and 2, the strains of 11 lactobacillus species all met two parameters defined for selection, i.e. an activity of at least 5x10 after 30 days of storage at 37 ℃³cfu(3.69log₁₀cfu) and a pH decrease of at most 0.6 units (i.e. a pH of at least 3.7): lactobacillus plantarum, Lactobacillus sourdough, Lactobacillus rosenbergii, Lactobacillus thalamus, Lactobacillus similis, Lactobacillus fermordelbrum, Lactobacillus acidovorans, Lactobacillus bulgaricus, Lactobacillus namulus, Lactobacillus delbrueckii and Lactobacillus jejuni.

Example 2: screening for Stable lactic acid bacteria (Strain)

These 11 Lactobacillus species were studied more intensively by determining A. After 30 days of storage at 37 ℃, the strains were classified into 4 types according to their viability and pH of the yoghurt (table 2).

TABLE 2: classification of strains with respect to their viability and their ability to lower pH

Table 3 and fig. 3 summarize the results obtained by assay a on 20 strains.

TABLE 3: log CFU and pH obtained with stabilized lactic acid bacteria after 30 days of storage at 37 ℃ (DSM32493v is a variant of DSM32493, whose G at position 506 of the ATP synthase alpha subunit gene is mutated to a compared to DSM32493 and generates the ATP synthase alpha subunit protein as defined by SEQ ID No. 5)

Therefore, these 20 strains were classified as follows:

3 strains in Category 1 (particularly high viability and particularly low pH decrease after storage)

8 strains in Category 2 (very high viability and very low pH drop after storage)

8 strains in Category 3 (high viability and low pH decrease after storage, or high viability and low pH decrease)

1 strain in category 4 (high viability and low pH reduction after storage).

These results show that assay a described herein is capable of selecting not only strains that retain high viability in yoghurt after 30 days storage at 37 ℃, but also strains that slightly lower the pH of the yoghurt after storage. These 20 strains are stable lactic acid bacteria and are suitable for the manufacture of food products which are stable at ambient temperature.

Example 3: production of food products stable at ambient temperature using Lactobacillus plantarum DSM32493

Yogurt with the following characteristics-2.8% protein, 3% fat, 8% sucrose; pH 4.3-Heat treatment to reduce bacterial levels to less than 1X10²CFU/g. At 1x10⁷The level of cfu/ml yoghurt was inoculated with the DSM32493 strain (classified in category 3 according to example 2).

The inoculated yoghurts were mixed, sealed and stored at 25 ℃ for 180 days. These conditions represent average ambient storage conditions when food items are stored outside the refrigerator or outside the fresh food compartment.

The pH and the amount of stabilized LAB (cell count) were determined on days 90, 120, 150 and 180 as described for assay a above. Strain viability and pH as a function of time are shown in fig. 4A and 4B, respectively.

After 180 days at 25 ℃ the amount of strain DSM32493 was 4.8log10 CFU, i.e.higher than 1x10⁴cfu/g product. This represents less than a 3log reduction in the amount of bacteria, confirming that DSM32493 can retain high viability after 6 months of storage at ambient temperature. Interestingly, the maximum amount reduction was obtained at day 150 and increased slightly between day 150 and day 180.

After 180 days at 25 ℃, the pH of the product was 3.67, i.e. representing a pH decrease of less than 0.7 units. Interestingly, the maximum pH drop was reached at day 90 and stabilized between day 90 and day 180.

These data confirm that the DSM32493 strain is a suitable lactic acid bacterium for the manufacture of food products stable at ambient temperature. This also more generally demonstrates that the following lactic acid bacteria are suitably stableLactic acid bacteria were targeted to make a food product stable at ambient temperature: the lactic acid bacteria were able to maintain 5x10 when selected by assay A³Viability of cfu/g was reduced up to 0.5 or maintained at 1x10 in conjunction with pH⁴Viability of cfu/g together with pH decrease of at most 0.6 (i.e., Classification in Category 3)

Example 4: use of a variant of Lactobacillus plantarum DSM32493 (DSM32493v) for the manufacture of a food product stable at ambient temperature

Yogurt with the following characteristics-2.8% protein, 3% fat, 8% sucrose; pH 4.3-Heat treatment to reduce bacterial levels to less than 1X10²CFU/g. At 1x10⁷The level of cfu/ml yoghurt was inoculated with the variant DSM32493v of the DSM32493 strain (classified in category 1 according to example 2). The inoculated yoghurts were mixed, sealed and stored at 25 ℃ for 180 days.

The pH and the amount of stabilized LAB (cell count) were determined on days 90, 120, 150 and 180 as described for assay a above. Strain viability and pH as a function of time are shown in fig. 5A and 5B, respectively.

After 180 days at 25 ℃ the amount of DSM32493v strain was 5.3log10 CFU, i.e.above 1X10⁵cfu/g product. This represents a less than 2log reduction in the amount of bacteria, confirming that DSM32493v can remain very viable after 6 months of storage at ambient temperature.

After 180 days at 25 ℃, the pH of the product was 3.77, i.e. representing a pH decrease of less than 0.6 units. Interestingly, the maximum pH drop was reached at day 90 and stabilized between day 90 and day 180.

These data confirm that the strain DSM32493v is a suitable lactic acid bacterium for the manufacture of food products stable at ambient temperature. This also more generally demonstrates that the following lactic acid bacteria are suitable stabilizing lactic acid bacteria to make a food product stable at ambient temperature: the lactic acid bacteria were able to maintain 1x10 when selected by assay A⁵The viability of cfu/g was reduced by at most 0.3 (i.e. classified in category 1) together with the pH.

Taken together, these data indicate that the strains selected according to assay a described herein proved suitable for the manufacture of food products that were stable at ambient temperature.

Example 5: identification of additional stable Lactobacillus plantarum strains

Additional lactobacillus plantarum strains of the danielco bacterial species pool, Dupont Danisco collection, were tested by assay a and their viability and pH of the yoghurt were determined after storage at 37 ℃ for 30 days. The results for 2 lactobacillus plantarum strains are described in table 4.

Bacterial strains	log CFU	pH	Classification
				Lactobacillus plantarum DSM33120	5.4	4.11	1
Lactobacillus plantarum DSM33121	5.7	4.08	1

TABLE 4: log CFU and pH obtained after 30 days of storage at 37 ℃ Using a Stable Lactobacillus plantarum Strain

The two identified strains of lactobacillus plantarum (DSM33120 and DSM33121) showed particularly high viability and a particularly low pH reduction after storage (when tested by assay a) and were classified as category 1. These 2 new strains are stable lactic acid bacteria and are suitable for the manufacture of food products which are stable at ambient temperature.

These results demonstrate that assay a described herein is capable of selecting not only strains that retain high viability in yoghurt after 30 days storage at 37 ℃, but also strains that slightly lower the pH of the yoghurt after storage.

Example 6: use of Lactobacillus plantarum DSM33120 or DSM33121 strains for the manufacture of a food product stable at ambient temperature

Yogurt with the following characteristics-2.8% protein, 3% fat, 8% sucrose; pH 4.3-Heat treatment to reduce bacterial levels to less than 1X10²CFU/g. At 1x10⁷The level of cfu/ml yoghurt was inoculated with the strain DSM33120 or DSM33121 (classified in Category 1 according to example 5).

The inoculated yoghurts were mixed, sealed and stored at 25 ℃ for 180 days. These conditions represent average ambient storage conditions when food items are stored outside the refrigerator or outside the fresh food compartment. The pH and the amount of stabilized LAB (cell count) were determined on days 90, 120, 150 and 180 as described for assay a above.

Strain viability and pH over time for the DSM33120 strain are shown in fig. 6A and fig. 6B, respectively. After 180 days at 25 ℃ the amount of DSM33120 strain was 5.96log10CFU, i.e.higher than 9X10⁵cfu/g product. This represents an approximately 1log reduction in the amount of bacteria, confirming that DSM33120 may remain very viable after 6 months of storage at ambient temperature. After 180 days at 25 ℃, the pH of the product was 3.75, i.e. it means that the pH decreased by less than 0.5 units.

Strain viability and pH over time for the DSM33121 strain are shown in fig. 7A and fig. 7B, respectively. After 180 days at 25 ℃ the amount of DSM33121 strain was 6.35log10CFU, i.e.higher than 2X10⁶cfu/g product. This represents less than a 0.7log reduction in the amount of bacteria, confirming that DSM333121 can remain very viable after 6 months of storage at ambient temperature. After 180 days at 25 ℃, the pH of the product was 3.87, i.e. it means that the pH decreased by less than 0.4 units.

These data confirm that the strains DSM33120 and DSM33121 are suitable lactic acid bacteria to make a food product stable at ambient temperature. This also more generally demonstrates that the following lactic acid bacteria are suitable stable lactic acid bacteria for the preparation ofFood product stable at ambient temperature: the lactic acid bacteria were able to maintain 1x10 when selected by assay A⁵The viability of cfu/g was reduced by at most 0.3 (i.e. classified in category 1) together with the pH.

PCT/RO/134 Table