DK153231B - CULTURE MEDIUM FOR PREPARING A BACTERIAL STARTER CULTURE - Google Patents

Description

DK 153231 B

The use of culture media added with citrate and phosphate recites in phage resistance and a larger and more uniform bacterial count in a starter culture. Cheese made using such a starter culture is stored faster and has a better aroma.

It is known to add citrates to various culture media, e.g. such containing decalcified milk products or increased concentrations of simple sugars to promote bacterial washing, cf. United States Patent 3,086,866 and 3,192,124. It is also known to add citric acid to a culture medium to produce a component of pleasant taste which is then added to a cheese product, cf. U.S. Patent No. 2,971,847.

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DK 153231 B

Furthermore, it is known to add phosphates to a cheese starter culture medium to inhibit the washing of bacteriophages, hereinafter referred to as phages, cf. U.S. Patent No. 3,354,049.

This known process requires high phosphate concentrations and low calcium concentrations and therefore requires the use of components such as demineralized whey.

In general, the known phage-resistant media are not as active as non-phage-resistant media, which is partly due to the elimination of. divalent calcium metals and other minerals in the media.

The reason that calcium-free components are used in starter culture media by the known methods is that calcium has been believed to be essential for phage infection by bacterial cells.

The present invention is based on culture media containing sweet whey, milk, a nitrogen source, citrate and phosphate and which does not require a decalcification source. The culture medium in question results in rapid bacterial growth, retention of highly skilled bacterial populations throughout the incubation period, and in bacteriophage resistance in the culture medium.

The culture medium of this invention contains per. 100 parts by weight on dry basis the following ingredients: (a) 20 to 95 parts of milk product containing a greater amount of sweet whey and a smaller amount of milk, (b) 0.1 to 30.0 parts of nitrogen source, (c) 1 to 30 parts of an added citrate, and (d) 1 to 20 parts of an added phosphate.

It is preferred that the milk product be present in an amount of from approx. 65 to 85 parts.

It is preferred that the nitrogen source be present in an amount of from 0.2 to approx. 10 parts.

It is preferred that the citrate be present in an amount of from ca. 5 to approx. 20 parts.

It is preferred that the phosphate be present in an amount of from ca. 1 to approx. 7 parts.

The above media causes higher bacterial counts than the known phage resistant starter culture media and also produces a more uniform bacterial count. The result is that the starter cultures prepared using the culture media of the present invention require a shorter incubation time than the known phage-resistant media.

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Another advantage of the present system is that calcium-containing sweet whey can be used as the milk product and that bacterial numbers greater than those normally obtained with the known phage-resistant media containing fat-free dry milk can be obtained. The sweet whey is not decalcified and contains at least 0.1 part calcium per day. 1000 parts sweet whey in the original liquid state.

It is preferred that the main component of the milk product is sweet whey and that a bee component of the product is fat-free (non-fat) milk. Sweet whey is whey with a pH of approx. 5.5 to approx. 6.5 in the original liquid state.

The milk in the milk product is preferably fat-free dry milk, but may include dry sweet milk. The corresponding liquid milk forms can also be used. Less preferred, but useful, are the corresponding dried buttermilk solids and liquid buttermilk.

The nitrogen source is selected from the group consisting of acid and enzyme degradation products or hydrolyzates of animal, vegetable and milk proteins such as yeast extract, yeast olysate, solubilized yeast, yeast, amino acids, meat extract, pancreatic extract, liver extract and other hydrolysates, casein extracts, casein peptides, peptides and mixtures thereof The nitrogen source is selected from those known as growth stimulants in bacterial culture media and will not be described in detail below. The above yeast products are the preferred nitrogen sources.

The preferred citrate is sodium citrate. Potassium and ammonium citrates also work well in starter cultures with the composition of this invention. Other non-toxic water-soluble citrate salts may also be used. Furthermore, citric acid can be used, which is not preferred, however, because of the decrease in the pH of the medium.

The preferred phosphates used in the practice of the present invention are the polyphosphates, especially sodium hexametaphosphate. Potassium and ammonium polyphosphates can also be very well used in starter cultures of the composition of the invention. Other useful phosphates include the phosphates disclosed in U.S. Patent Nos. 3,354,049 and No. 3,041,248. These include primary, secondary and tertiary phosphate salts such as monosodium, disodium, trisodium, monocalcium, dipotassium, tricalium, monoammonium, diammonium sodium hydrogen pyrophosphate, tetrasodium phosphate phosphate, tetrakalium pyrophosphate, sodium tripolyphosphate, sodium triphosphate, sodium triphosphate

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The required amounts of phosphate and citrate are interdependent in that the more phosphate added to achieve bacteriophage resistance, the less citrate is needed and vice versa. For example, when the citrate concentration is approx. 20 parts, only approx. 1 part phosphate. When the phosphate concentration is approx. 7 parts, only approx. 1 part citrate to increase phage resistance and promote bacterial growth. In practice, the total amount of phosphate and citrate does not exceed 30 parts. In this case, the minimum amount of milk product is 40 parts. Preferably, the total amount of phosphate and citrate does not exceed 20 parts. In this case, the minimum amount of milk product is 70 parts.

The production of large amounts of lactic acid in the starter culture and the maintenance of a good bacterial flora are related to the buffering ability of the citrate and phosphate present. The combination of sodium citrate and sodium hexametaphosphate has been found to be useful in this regard.

Other ingredients which may be added to the above material for use in a cheese starter culture medium include the following: 1. Water may, for example, add such amount that the final solution or suspension contains 30-40% solids.

2. Vitamins such as folic acid, ascorbic acid, thiamine, riboflavin and pantothenic acid.

3. Acids such as oleic acid and aminobenzoic acid.

4. Minerals such as manganese, magnesium, iron and potassium.

5. Purines and pyrimidines such as adenine, guanine, uracil and xanthine.

6. Saccharides such as lactose, sucrose, dextrose, hydrolyzed starch and corn syrup solid.

For the purpose of storage, transport and maintenance of stable conditions, it is preferred that the mixture be present in the dry state. The production procedure for culture media is well known and is therefore not further described.

The bacteria used are those commonly used in starter cultures in the production of cheese and include Streptococcus cremoris, Streptococcus lactis, Streptococcus citrovorus, Streptococcus paracitrocorus, Streptococcus thermophilus, Streptococcus faeca-lisacillus, Lactobacillus acidophilus, Lactobacillus acidophilus, Lactobacillus acidophilus lactis, Lactobacillus plantarum, Lactobacillus thermophilus, Leuconostoc mesenteric Λλο nrr Dr * An-5 irm enonτ ^ c? orr Kl n / r / ar / laraf

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The bacteria normally used in cheese making and preferred by the present invention are Streptococcus cremoris, Streptococcus thermophilus, Lactobacillus bulgaricus, Streptococcus lactis, Streptococcus citrovorus, Propionibacterium shermanii and mixtures thereof.

The starter culture in question is used in much the same way as conventional starter cultures have been used. A notable difference is that less of the starter culture in question is required than of the known starter cultures. Other notable differences are that the starter culture of the present invention can be used sooner or later than conventional starter cultures with a significantly better result than is usually achieved by using the known starter cultures.

The invention is explained in more detail in the following examples, where all parts are by weight unless otherwise stated. The acidity is titratable acidity, expressed as a percentage of lactic acid, unless otherwise stated.

Example 1

A culture medium is prepared by dry mixing the following ingredients: 69 ingredients sweet whey 11 parts fat-free dry milk 2 parts autolysed yeast 16 parts sodium citrate 2 parts sodium hexametaphosphate.

To 88.5 parts of water at 43 ° C, 11.5 parts of the dry culture medium is added with good stirring. After the dry mixture has dissolved, the solution is heated to 85 ° C and maintained at this temperature for 40 minutes to pasteurize the medium. Then the solution is quickly cooled to 21 ° C. The solution is divided into 3 parts and each part inoculated with a concentrated culture. The ratio of concentrated culture to solution is 1 part of concentrated culture per ml. 5000 parts solution. The three concentrated cultures are Hansen's No. 70, Hansen's No. 72, and Marschall's MD. All of these three cultures are commercial cheddar cheese type cultures containing a mixture of Streptococcus lactis and Streptococcus cremoris.

The inoculated culture solutions are incubated at 22 ° C and a standard plate count is made on each of the incubated starter culture media after 8, 10, 12, 14, 16 and 24 hours. The results are given in the table below.

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DK 153231 B

Table

Hours no. 70 No. 72 MD

8 18 24 62 10 58 95 138 12 132 420 450 14 31 115 83 16 470 310 360 24. 271 520 169

For comparison purposes, two starter cultures of the known type are prepared in exactly the same way. The dry mixture of the first culture medium contains 17.0 parts of demineralized whey, 67.5 parts of fat-free dry milk, 0.2 parts of pancreatic extract, 5.1 parts of diammonium phosphate and 5.1 parts of disodium phosphate. The dry mixture for the second culture medium contains 16.9 parts of demineralized whey, 51.0 parts of fat-free dry milk, 0.2 parts of pancreatic extract, 3.8 parts of monoammonium phosphate, 4.8 parts of diammonium phosphate, 6.5 parts of sodium phosphate and 16.8 parts of lactose.

The inoculated media is incubated at 22 ° C as above, and a standard plate count is made on each of the incubated starter culture media after 8, 10, 12, 14, 16 and 24 hours. The results are given in the table below.

Table

Culture medium I

Hours no. 70 No. 72 MD

8 0.1 0.3 2.7 10 6.3 4.0 16.4 12 14 17 33 14 22 39 4 16 123 118 13 24 72 94 2

Culture medium II

Hours no. 70 No. 72 MD

8 0.1 0.2 1.1 10 0.5 0.6 1.6 12 4 2 4 14 111 16 5 36 6 24 36 160 1 7

DK 155231B

The plate count method used is the standard plate method described in the Standard Method for the Examination of Dairy Products published by the American Public Health Association, 13th Edition

C

(1972) (results are given in viable cells x 10 per ml).

Examples 2-8

A number of starter cultures have been prepared by dry mixing the following ingredients:

Example 2 69.0 parts sweet whey powder 11.0 parts fat-free dry milk 2.0 parts autolysed yeast 10.0 parts sodium citrate 8.0 parts sodium hexametaphosphate

Example 3 69.0 parts sweet whey powder 11.0 parts fat-free dry milk 2.0 parts autolysed yeast 12.0 parts sodium citrate 6.0 parts sodium hexametaphosphate

Example 4 69.0 parts sweet whey powder 11.0 parts fat-free dry milk 2.0 parts autolysed yeast 14.0 parts sodium citrate 4.0 parts sodium hexametaphosphate

Example 5 69.0 parts sweet whey powder 11.0 parts fat-free dry milk 2.0 parts autolysed yeast 16.0 parts sodium citrate 2.0 parts sodium hexametaphosphate

Example 6 69.0 parts sweet whey powder 11.0 parts fat-free dry milk 2.0 parts autolysed yeast 17.0 parts sodium citrate 1.0 parts sodium hexametaphosphate

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Example 7 69.0 parts sweet whey powder 11.0 parts fat-free dry milk 2.0 parts autolysed yeast 17.5 parts sodium citrate 0.5 parts sodium hexametaphosphate

Example 8 69.0 parts sweet whey powder 11.0 parts fat-free dry milk 2.0 parts autolysed yeast 18.0 parts sodium citrate In each example, 11.5 parts of the dry culture medium is added to 88.5 parts of water at 43 ° C with good stirring. After the dry mixture has dissolved, the solution is heated to 85 ° C and maintained at this temperature for 40 minutes to pasteurize the medium. Then the solution is quickly cooled to 21 ° C. The individual solutions are inoculated with a concentrated culture of Streptococcus lactis and Streptococcus cremoris. The ratio of concentrated culture to solution is 1 part culture per 5000 parts solution. A control based on fat-free dry milk is also inoculated with the same culture. Each solution and control are also seeded with a phage capable of lysing the streptococcus bacteria at a ratio of ca. one subject per 1000 bacterial cells.

The subject used is isolated from a commercial culture. The samples are incubated for 16 hours at 22 ° C and tested for titratable acidity. The test covers three row transfers from each example.

It is evident from the results that the media used in Examples 2-6 exhibit phage inhibition, while the media used in Examples 7 and 8 do not exhibit phage inhibition. This is shown in the results given in the following table.

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Table y

Example Transfers 12 3

Free medium w / phage 0.17 0.16 0.16

Fat-free medium w / o phage 0.76 6.70 0.73 2 w / ph 1.13 1/14 1/14 2 w / o phage 1.14 1.13 1.14 3 w / phage 1.14 1 , 13 1.17 3 w / o phage 1.09 1.13 1.17 4 w / ph 1.12 1.14 1.15 4 w / o phage 1.08 1.13 1.15 5 w / phage 1.11 1.11 1.14 5 w / o phage 1.09 1.11 1.12 6 w / ph 1.06 1.11 1.10 6 w / o phage 1.07 1.11 1.08 7 w / ph 1.08 0.62 0.17 7 w / o ph 1.08 1.12 1.08 8 w / ph 1.05 0.73 0.16 8 w / o ph 1.02 1, 14 1.05 KTitrable acidity in these examples and in the description otherwise is percent lactic acid.

Example 9

A culture medium is prepared by dry mixing the following ingredients: 68.0 parts sweet whey powder 11.0 parts fat-free dry milk 2.0 parts autolysed yeast 11.0 parts sodium citrate 8.0 parts sodium hexametaphosphate 11 parts of the dry culture medium are added to 89 parts water at 43 ° C with good stirring. After dissolving the dry mixture, the solution is heated to 85 ° C and maintained at this temperature for 40 minutes to pasteurize the medium. Then the solution is quickly cooled to 21 ° C. The solution is inoculated with a concentrated culture of Streptococcus lactis and Streptococcus cremoris. The ratio of concentrated culture to solution is 1 part of concentrated culture per ml. 5000 parts solution. Each of the solutions is also inoculated with a phage capable of lysing the streptococcus bacteria at about one subject per 1000 bacterial cells.

DK 153231 B

10 Φϋ SaBiBiS Equation Purpose For Another Starter Culture Get the exact same way, though using 11 parts of fat-free dry milk added to 89 parts of water as a culture medium. The samples are incubated for 16 hours at -22 ° C.

The results show that there is complete phage resistance in the citrate-phosphate medium, whereas the control medium containing fat-free milk does not exhibit resistance to phage growth.

Example 10

Culture media is prepared by dry mixing the following ingredients:

Sample 1 69 parts sweet whey powder 11 parts fat-free dry milk 2 parts autolyzed yeast 16 parts sodium citrate 2 parts sodium hexametaphosphate

Sample 2 69 parts sweet whey powder 11 parts fat-free dry milk 2 parts autolyzed yeast 14 parts sodium citrate 4 parts sodium hexametaphosphate

Sample 3 69 parts sweet whey powder 11 parts fat-free dry milk 2 parts autolyzed yeast 12 parts sodium citrate 6 parts sodium hexametaphosphate

The individual media is prepared by adding 88.5 parts of water at 43 ° C with good stirring to 11.5 parts of the individual dry culture media. After dissolving the dry mixture, the solution is heated to 85 ° C and maintained at this temperature for 40 minutes to pasteurize the medium. Then the solution is quickly cooled to 21 ° C.

For comparison purposes, a starter culture is prepared in exactly the same way, with the exception that 11.5 parts of fat-free dry milk is added to 88.5 parts of water and used as a culture medium.

A set of the test samples and the control sample with fat-free dry milk are inoculated with a culture of Streptococcus lactis 7962, obtained from

DK 153231B

11

University of Minnesota, and also inoculated with a phage capable of lysing the bacteria in a ratio of ca. one subject per 1000 bacterial cells. The samples are incubated for 16 hours at 22 ° C and tested for titratable acidity, standard plate number, phage count and pH. The test covers three row transfers from each sample.

In the table below, (TA) 3 is titratable acidity at the end of the 16 hours minus the titration rate at 0 hours. TPC is the total bacterial plate number in living cells per cell. and PFU is the total plaque forming units per ml. ml. MSND is fat-free dry milk powder.

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Example 11

Culture media is prepared by dry mixing the following ingredients:

Sample 1 69 parts sweet whey powder 11 parts fat-free dry milk 2 parts autolyzed yeast 16 parts sodium citrate 2 parts sodium hexametaphosphate

Sample 2 62 parts sweet whey powder 11 parts fat-free dry milk 2 parts autolyzed yeast 14 parts sodium citrate 4 parts sodium hexametaphosphate

Sample 3 69 parts sweet whey powder 11 parts fat-free dry milk 2 parts autolyzed yeast 12 parts sodium citrate 6 parts sodium hexametaphosphate

The individual media is prepared by adding 88.5 parts of water at 43 ° C with good stirring to 11.5 parts of the dry culture medium. After dissolving the dry mixture, the solution is heated to 85 ° C and maintained at this temperature for 40 minutes to pasteurize the medium. The solution is then cooled rapidly to 70 ° C.

For comparison purposes, a starter medium is prepared in exactly the same way, however, 11.5 parts of fat-free dry milk is added to 88.5 parts of water and used as a culture medium.

A set of the test samples and the control sample with fat-free dry milk is inoculated with a culture of Streptococcus cremoris HP, obtained from the University of Minnesota, and also inoculated with a phage capable of lysing the bacteria in a ratio of approx. one subject per 1000 bacterial cells. The samples are incubated for 16 hours at 21 ° C and tested for titratable acidity, plate number, phage number and pH. The test covers three serial transfers from each sample.

In the table below, (TA) D means titratable acidity at the end of 16 hours minus the titratable acidity at 0 hours.

TPC is the total bacterial plate number in living cells per cell. and PFU is the total plaque forming units per ml. ml, MSNF is fat-free dry milk powder.

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Example 12

Culture media is prepared by dry mixing the following ingredients:

Sample 1 69 parts sweet whey powder 11 parts fat-free dry milk 2 parts autolyzed yeast 16 parts sodium citrate 2 parts sodium hexametaphosphate

Sample 2 69 parts sweet whey powder 11 parts fat-free dry milk 2 parts autolyzed yeast 14 parts sodium citrate 4 parts sodium hexametaphosphate

Sample 3 69 parts sweet whey powder 11 parts fat-free dry milk 2 parts autolyzed yeast 12 parts sodium citrate 6 parts sodium hexametaphosphate

The individual media is prepared by adding 88.5 parts of water at 43 ° C with good stirring to 11.5 parts of the above dry mixtures.

After dissolving the dry mixture, the solution is heated to 85 ° C to pasteurize the medium and kept at this temperature for 40 minutes. The solutions are then rapidly cooled to 21 ° C.

For comparison purposes, a starter culture is prepared in exactly the same way, however, 11.5 parts of fat-free cow's milk is added to 88.5 parts of water and used as a culture medium.

One set of the test specimens and the control of fat-free dry milk is inoculated with a culture of Streptococcus lactis ML 3, obtained from the University of Minnesota, and also inoculated with a phage capable of lysing the bacteria relative to ca. one subject per 1000 bacterial cells. The samples are incubated for 16 hours at 21 ° C and tested for titratable acidity, plate number and phage count as well as pH. The test covers three serial dilutions from each sample.

In the table below, (TA) D means titratable acidity after 16 hours minus the titratable acidity at 0 hours. TPC is the total bacterial plate number in living cells per cell. and PFU are total plaque forming units per ml. ml. MSNF is fat-free dry milk powder.

16 DK 153231B

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Example 13

Culture media is prepared by dry mixing the following ingredients:

Sample 1 69 parts sweet whey powder 11 parts fat-free dry milk 2 parts autolyzed yeast 16 parts sodium citrate 2 parts sodium hexametaphosphate

Sample 2 69 parts sweet whey powder 11 parts fat-free dry milk 2 parts autolyzed yeast 14 parts sodium citrate 4 parts sodium hexametaphosphate

Sample 3 69 parts sweet whey powder 11 parts fat-free dry milk 2 parts autolyzed yeast 12 parts sodium citrate 6 parts sodium hexametaphosphate

The individual media is prepared by adding 88.5 parts of water at 43 ° C with good stirring to 11.5 parts of the dry mixtures. After dissolving the dry mixture, the solution is heated to 185 ° C to pasteurize the medium and maintained at this temperature for 40 minutes. The solution is then cooled rapidly to 21 ° C.

For comparison purposes, another starter culture is prepared in exactly the same way, however, 11.5 parts of fat-free dry milk is added to 88.5 parts of water and used as a culture medium.

One set of test specimens and the control of fat-free dry milk are inoculated with a culture of Streptococcus lactis C2, obtained from the University of Minnesota, and inoculated with a phage capable of lysing the bacteria relative to ca. one subject per 1000 bacterial cells. The samples are incubated for 16 hours at 21 ° C and tested for titratable acidity, plate number, phage count and pH. The test covers three serial dilutions from each sample.

In the table below, (TA) D means titratable acidity after 16 hours minus the titratable acidity at 0 hours. TPC is the total bacterial plate number in living cells per cell. and PFU are total plaque forming units per ml. ml, MSNF is fat-free dry milk powder.

DK 153231B

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19 DK 153231B

Example 14

Culture media is prepared by dry mixing the following ingredients:

Sample 1 60 parts sweet whey powder 20 parts fat-free dry milk 3 parts autolyzed yeast 2 parts sodium citrate 15 parts sodium hexametaphosphate

Sample 2 61 parts sweet whey powder 20 parts fat-free dry milk 3 parts autolyzed yeast 8 parts sodium citrate 8 parts sodium hexametaphosphate

Sample 3 59 parts sweet whey powder 20 parts fat-free dry milk 3 parts autolyzed yeast 14 parts sodium citrate 4 parts sodium hexametaphosphate

Sample 4 57 parts sweet whey powder 20 parts fat-free dry milk 3 parts autolyzed yeast 18 parts sodium citrate 2 parts sodium hexametaphosphate

Sample 5 52 parts sweet whey powder 20 parts fat-free dry milk 3 parts autolyzed yeast 24 parts sodium citrate 1 part sodium hexametaphosphate

Sample 6 61.8 parts sweet whey powder 20.0 parts fat-free dry milk 0.2 parts autolysed yeast 16.0 parts sodium citrate 2.0 parts sodium hexametaphosphate

2 ° DK 153231 B

Sample 7 62 Dole Calipers Pullover 10 parts fat-free dry milk 10 parts autolysed yeast 16 parts sodium citrate 2 parts sodium hexametaphosphate

Sample 8 52 parts sweet whey powder 10 parts fat-free dry milk 20 parts autolyzed yeast 16 parts sodium citrate 2 parts sodium hexametaphosphate

Sample 9 47 parts sweet whey powder 10 parts fat-free dry milk 25 parts autolysed yeast 16 parts sodium citrate 2 parts sodium hexametaphosphate

Sample 10 69 parts sweet whey powder 11 parts fat-free dry milk 2 parts autolyzed yeast 16 parts sodium citrate 2 parts sodium hexametaphosphate

Sample 11 25 parts sweet whey powder 25 parts dextrin 20 parts fat-free dry milk 10 parts autolysed yeast 16 parts sodium citrate 4 parts sodium hexametaphosphate

Sample 12 40 parts sweet whey powder 29 parts lactose 11 parts fat-free dry milk 2 parts autolysed yeast 16 parts sodium citrate 2 parts sodium hexametaphosphate

Sample 13

2i DK 153231 B

40 parts sweet whey powder 29 parts dextrose 11 parts fat-free dry milk 2 parts autolysed yeast 16 parts sodium citrate 2 parts sodium hexametaphosphate

The individual solutions are prepared by adding 88.5 parts of water at 43 ° C with good stirring to 11.5 parts of the dry mixtures. After dissolving the dry mixture, the solution is heated to 85 ° C and maintained at this temperature for 40 minutes to pasteurize the medium. The solution is then cooled rapidly to 21 ° C.

One set of samples is inoculated with a commercial culture, Hansen's 72, and another set of samples is inoculated with another commercial culture, Marschall's MRD. The samples are incubated for 16 hours at 21 ° C and tested for titratable acidity.

In the table below, (TA) µg means the titratable acidity after 16 hours.

Table

Sample Culture (TA) 16 1 Hansens No. 72 1.15

Marshal MRD 1.00 2 Hansens No. 72 1.20

Marshal MRD 1.07 3 Hansens No. 72 1.20

Marshal MRD 1.09 4 Hansens no, 72 1.21

Marshal MRD 1.13 5 Hansens No. 72 1.28

Marshal MRD 1.23 6 Hansens No. 72 1.07

Marshal MRD 1.06 7 Hansens No. 72 1.25

Marshal MRD 1.16 8 Hansens No. 72 1.35

Marshal MRD 1.25 9 Hansens No. 72 1.38

Marshal MRD 1.26 10 Hansens No. 72 1.15

Marshal MRD 1.08 11 Hansens No. 72 1.26

Marshall MRD 1.16 12 Hansens No. 72 1.09

Marshal MRD 0.99 13 Hansens No. 72 1.09

Marshal MRD 1.06

Claims (6)

1. Culture medium for the preparation of a bacterial starting culture, characterized in that 100 parts by weight on a dry basis contain the following ingredients: (a) 20 to 95 parts of a milk product containing a major constituent of sweet whey and a minor constituent of milk, (b) 0.1 to 30.0 parts of a nitrogen source, (c) 1 to 30 parts of an added citrate, and (d) 1 to 20 parts of an added phosphate. Medium according to claim 1, characterized in that the milk product is present in an amount of 63 to 85 parts. Medium according to claim 1 or 2, characterized in that the nitrogen source is present in an amount of from 0.2 to 10.0 parts. Medium according to any one of claims 1-3, characterized in that the citrate is present in an amount of from 5 to 20 parts. The medium according to any one of claims 1-4, characterized in that the phosphate is present in an amount of from 1 to 7 parts. The medium according to any one of claims 1-5, characterized in that the citrate is sodium citrate.