<i>Lactobacillus rhamnosus </i>for use in preparation of fermented products

Abstract

The present invention relates to a novel strain of Lactobacillus rhamnosus, compositions comprising said strain and to methods for the preparation of such compositions.

Claims

1. A dairy composition comprising milk and Lactobacillus rhamnosus strain deposited at CNCM under reference number 1-4993.

2. The dairy composition according to claim 1, comprising at least 10.sup.5 CFU/g of the Lactobacillus rhamnosus strain.

3. The dairy composition according to claim 2, wherein said dairy composition is an inoculum.

4. The dairy composition according to claim 3, wherein said dairy composition is fresh, frozen, dried or lyophilized.

5. The dairy composition according to claim 1, wherein said dairy composition is a yogurt.

6. The dairy composition according to claim 1, wherein said dairy composition is a fermented composition.

7. The dairy composition according to claim 1, further comprising at least one, two, three or more strains of Bifidobacterium or lactic acid bacteria.

8. The dairy composition according to claim 7, wherein said dairy composition is fresh, frozen, dried or lyophilized.

9. The dairy composition according to claim 7, wherein said dairy composition comprises at least two strains of lactic acid bacteria, wherein said strains of lactic acid bacteria comprise at least one strain of Lactobacillus bulgaricus and at least one strain of Streptococcus thermophilus.

10. The dairy composition according to claim 9, further comprising one or more strains selected from the group consisting of Lactococcus lactic and/or Bifidobacterium.

11. The dairy composition of claim 1, wherein the milk is vegetal milk.

12. The dairy composition of claim 11, wherein the vegetal milk is soya, almond, oat, hemp, spelt, coconut, or rice milk.

13. The dairy composition of claim 1, wherein the milk is animal milk.

14. The dairy composition of claim 13, wherein the animal milk is goat, ewe, camel, mare or cow milk.

15. A method for the preparation of a fermented dairy product comprising fermenting a mixture comprising: a) milk; and b)L. rhamnosus CNCM 1-4993 to provide a fermented dairy product.

16. The method according to claim 15, wherein the mixture comprises at least one, two, three or more strains of Bifidobacterium or lactic acid bacteria.

17. The method according to claim 16, wherein the mixture comprises at least two strains of lactic acid bacteria, wherein said strains of lactic acid bacteria comprise at least one strain of Lactobacillus bulgaricus and at least one strain of Streptococcus thermophilus.

18. A fermented food product comprising Lactobacillus rhamnosus strain deposited at CNCM under reference number 1-4993.

Description

DESCRIPTION OF THE FIGURES

(1) FIG. 1 shows the levels of acetoin and diacetyl in parts per million (PPM) produced by 20 bacterial strains tested according to Example 1.

(2) FIG. 2 shows the global sensory profile of test and control products evaluated by consumer according to Example 3. Each sensory characteristic is evaluated on a scale of 1-5 and the plot shows the average of the 11 testers: A=dairy notes, B=sweetness, C=acidity, D=thickness in mouth, E=thickness in spoon. The dark grey plot represents the control product, the light grey plot represents the test product.

(3) FIG. 3 shows the dairy notes flavour profile of test and control products evaluated by consumer according to Example 3. X-axis shows the frequency of identification of a specified dairy note characteristic in the 11 tasters. Dairy notes are provided in the Y-axis: A=milky, B=yogurt acidity, C=creamy, D=cheesy, E=buttery. Dark grey bars represent the control product, light grey bars represent the test product.

(4) FIG. 4 shows the milk acidification kinetics of control and test products prepared according to Example 3. Time in hours is provided on the x-axis, pH is represented on the y-axis. The dark grey plot represents the test product, the light grey plot represents the test product.

(5) FIG. 5 shows the milk acidification kinetics of Batch 1 carried out according to Example 2. Time in minutes is provided on the x-axis, pH is represented on the y-axis.

EXAMPLES

(6) Example 1: Strain Selection

(7) A total of 65 strains of Lactobacillus and Bifidobacterium were screened for production of acetoin & diacetyl. The strains included 37 Bifidobacterium, 3 Streptococcus salivarius subspecies thermophilus and 25 Lactobacillus (4 L. delbrueckii, 1 L. helveticus, 1 L. amylovorus, 3 L. jonhsonii, 6 L. paracasei, 8 L. rhamnosus and 2 L. plantarum).

(8) Reconstituted milk was prepared by mixing 110 g skimmed milk powder (Arla) per litre permuted water and pasteurized at 95° C. for 45 minutes. Each strain was grown in milk for 16 hours at 37° C. and acetoin & diacetyl production was analyzed by static head space gas chromatography using a Autosystem XL GC fitted with a flame ionization detector (Perkin Elmer, Waltham, US). Concentration of acetoin and diacetyl (ppm) in samples was determined using response factors coming from standards.

(9) Of the 65 tested strains only 20 strains were able to produce at least 6 ppm of acetoin. Results are provided for these 20 strains in FIG. 1. As can be seen the strain of the invention was the best producer of both acetoin & diacetyl. The combined amount of acetoin & diacetyl produced was more than twice the amount of the next best strain.

(10) Example 2: Milk Fermentation

(11) Reconstituted milk was prepared by mixing 112 g skimmed milk powder (Arla) per litre permuted water and pasteurized at 99° C. for 30 minutes. Bacteria strains were provided in the form of frozen pellets, L. rhamnosus CNCM I-4993 was supplied by Danone. Strains were inoculated in reconstituted milk after defrosting. Fermentation was carried out at 37° C. and monitored using a pH probe. L. rhamnosus CNCM I-4993 was tested in 2 batches, each batch consisting of 3 individual tests at various inoculation rates.

(12) Results

(13) TABLE-US-00001 pH at max. Lag phase acidification (minutes) velocity Time to pH 4.5 (minutes) Batch 1 Test 1 445 5.61 1948 Innoculation 0.01% volume Batch 1Test 2 353 5.59 1652 Innoculation 0.02% volume Batch 1Test 3 443 5.54 1852 Innoculation 0.01% volume Batch 2 Test 1 416 5.90 988 Innoculation 0.01% volume Batch 2Test 2 328 5.80 940 Innoculation 0.02% volume Batch 2Test 3 428 5.46 1632 Innoculation 0.01% volume

(14) Acidification curves of Batch 1 are provided in FIG. 5.

Example 3: Fermented Milk Product Preparation & Sensory Evaluation

(15) A fermented milk product was prepared by fermentation of a pasteurized milk base (6.64% skim milk powder; 93.06% milk; 0.3% whey protein concentrate) with a standard yogurt starter culture (L. delbrueckii, S. thermophilus & yeast extract) as control product. The control product ferment was supplemented with L. rhamnosus CNCM I-4993 to prepare a test product by fermentation of said milk base. Fermentation kinetics are provided in FIG. 4, as can be seen the test product had a higher initial rate of acidification.

(16) Sensory evaluation was carried out by 11 testers who evaluated the dairy notes of the flavour profile and a global sensory profile of the control and test products. The testers assessed the organoleptic characteristics dairy notes (A), sweetness (B), acidity (C), thickness in mouth (D), thickness in spoon (E) on a scale of 1 to 5. Average values for all characteristics were used to generate average value scores for each characteristics, these results are provided in FIG. 2. FIG. 3 shows the frequency of identification of the characteristics by the panel. These results demonstrate that the test product was thicker in the spoon and mouth. The addition of the strain of the invention also changed the flavour profile of the fermented dairy product, providing a product that was clearly more creamy, cheesy and buttery but that was also perceived as less milky while providing a good level of acidity that is considered standard in fermented milk products such as yogurt.