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Title:
PROCESS FOR PRODUCING A HEAT-TREATED FERMENTED MILK PRODUCT
Document Type and Number:
WIPO Patent Application WO/2018/041869
Kind Code:
A1
Abstract:
The invention relates to a process of producing a heat-treated fermented milk product comprising the steps of a) fermentation of a milk substrate using a starter culture of lactic acid bacteria at a fermentation temperature until a target pH of between 3.80 and 4.39 is reached to obtain a starter culture fermented milk product, and b) subjecting the starter culture fermented milk product to a heat treatment so as to reduce the level of bacteria of the starter culture to obtain a heat-treated fermented milk product, -wherein step b) is carried out within a period of less than 24 hours from reaching the target pH in step a), -wherein the starter culture fermented milk product is not subjected to cooling between step a) and b), -wherein no sugar-containing composition is added after step a), and -wherein the starter culture in a fermentation of a milk substrate, which contains 3.0 % protein, after reaching a target pH of 4.3 and at a temperature of 43 ⁰C generates a post-acidification of below 0.30 pH units in 7hours.

Inventors:
GILLELADEN, Christian (Enghavevej 55, 1 sal, 1674 Copenhagen V, 1674, DK)
SUNDBERG, Maria Elina (Helgesvej 6A, 2tv, 2000 Frederiksberg, 2000, DK)
BIRLOUET, Benoit (Bygvaenget 237, 2980 Kokkedal, 2980, DK)
SVANE, Claus (Valdemarsvej 20, 2960 Rungsted Kyst, 2960, DK)
Application Number:
EP2017/071716
Publication Date:
March 08, 2018
Filing Date:
August 30, 2017
Export Citation:
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Assignee:
CHR. HANSEN A/S (Boege Alle 10-12, 2970 Hoersholm, 2970, DK)
International Classes:
A23C9/12
Domestic Patent References:
WO2010139765A22010-12-09
WO2015193459A12015-12-23
WO2010139765A22010-12-09
WO2015193459A12015-12-23
Foreign References:
JPS61132140A1986-06-19
US3539363A1970-11-10
US4235934A1980-11-25
CH634464A51983-02-15
EP1869983A12007-12-26
Other References:
"Fermented Milk Products", 2015, TETRAPAK® PROCESSING SYSTEMS AB, article "Heat treatment of yogurt"
ZHEN-MIN LIU ET AL.: "Efficacy of pasteurized yogurt in improving chronic constipation: A randomized, double-blind, placebo-controlled trial", INTERNATIONAL DAIRY JOURNAL, vol. 40, 2015, pages 1 - 5
J. S. ALAKALI ET AL.: "Effect of whey protein enrichment on selected engineering and sensory properties of Pasteurized yogurt", AFRICAN JOURNAL OF FOOD SCIENCE, vol. 5, no. 7, April 2011 (2011-04-01), pages 392 - 399
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Claims:
CLAIMS

1. Process of producing a heat-treated fermented milk product comprising the steps of a) fermentation of a milk substrate using a starter culture of lactic acid bacteria at a fermentation temperature until a target pH of between 3.80 and 4.39 is reached to obtain a starter culture fermented milk product, and b) subjecting the starter culture fermented milk product to a heat treatment so as to reduce the level of bacteria of the starter culture to obtain a heat-treated fermented milk product,

- wherein step b) is carried out within a period of less than 24 hours from reaching the target pH in step a),

- wherein the starter culture fermented milk product is not subjected to cooling between step a) and b),

- wherein no sugar-containing composition is added after step a), and

- wherein the starter culture in a fermentation of a milk substrate, which contains 3.0 % protein, after reaching a target pH of 4.3 and at a temperature of 43 °C generates a post-acidification of below 0.30 pH units in 7 hours. 2. Process according to claim 1, wherein step b) is carried out within a period of less than 20 hours, preferably 15 hours, more preferably 10 hours, more preferably 7 hours, more preferably 5 hours from reaching the target pH in step a). 3. Process according to claim 1 or 2, wherein the target pH is from 3.80 to 4.38, preferably from 3.80 to 4.37, more preferably from 3.80 to 4.36, more preferably from 3.80 to 4.35, more preferably from 3.80 to 4.34, more preferably from 3.80 to 4.33, more preferably from 3.80 to 4.32, more preferably from 3.80 to 4.31, more preferably from 3.80 to 4.30, more preferably from 3.90 to 4.30, and most preferably from 4.00 to 4.30.

4. Process according to any of claims 1-3, wherein the milk substrate used for the fermentation with the starter culture contains a sugar-containing

composition.

5. Process according to any of claims 1-4, wherein the sugar-containing composition is selected from the group consisting of an artificial sugar; a High Intensity Natural Sweetener; and a sugar syrup, a puree, a juice and a nectar obtained from a source selected from the group consisting of a fruit, a vegetable and a grain source.

6. Process according to any of claims 1-5, wherein the starter culture fermented milk product is subjected to a heat treatment so as to reduce the level of bacteria of the starter culture to no more than 1.0X10exp02 CFU per g fermented milk. Preferably, the level of bacteria of the starter culture is reduced to no more than l .OXlOexpOl CFU per g fermented milk, more preferably 0 CFU per g .

7. Process according to any of claims 1-6, wherein the starter culture fermented milk produced in step a) is transported directly from step a) to the heat treatment step b) .

8. Process according to any of claims 1-7, wherein the starter culture in a fermentation of a milk substrate, which contains 3.0 % protein, 2.8 % fat and 1.5 % modified starch, is capable of generating a starter culture fermented milk product with a shear stress measured at 300 1/s of above 50 Pa, preferably above 60 Pa, more preferably above 70 Pa, and most preferably above 80 Pa .

9. Process according to any of the claims 1-8, wherein the starter culture, the starter culture in a fermentation of a milk substrate, which contains 3.0 % protein, after reaching a target pH of 4.3 and at a temperature of 43 °C generates a post-acidification of below 0.25 pH units in 7 hours, preferably below 0.20 pH units in 7 hours, more preferably below 0.15 pH units in 7 hours, more preferably below 0.10 pH units in 7 hours, and most preferably below 0.05 pH units in 7 hours.

10. Process according to any of the claims 1-8, wherein the starter culture in a fermentation of a milk substrate, which contains 3.0 % protein, after reaching a target pH of 4.3 and at a temperature of 43 °C generates a post-acidification of below 0.30 pH units in 10 hours, more preferably below 0.25 pH units in 10 hours, more preferably below 0.20 pH units in 10 hours, more preferably below 0.15 pH units in 10 hours, more preferably below 0.10 pH units in 10 hours, and most preferably below 0.05 pH units in 10 hours. 11. Process according to any of claims 1-10, wherein the starter culture has an acidification capacity so that the fermented milk product reaches a pH of 4.3 in less than 12 hours, preferably less than 10 hours, more preferably less than 9 hours, more preferably less than 8 hours, and most preferably less than 7 hours. 12. Process according to any of claims 1-11, wherein the heat-treated fermented milk product produced by the process of the invention has a shear stress measured at 300 1/s of above 30 Pa, preferably above 35 Pa, more preferably above 40 Pa, more preferably above 45 Pa, more preferably above 50 Pa, more preferably above 55 Pa, and most preferably above 60 Pa.

13. Process according to any of claims 1-12, wherein the milk substrate contains texturizing agents in a total amount of from 0,5 % by weight (w/w) to 5.0 % by weight (w/w), more preferably from 1.0 % by weight (w/w) to 4.0 % by weight (w/w), more preferably from 1.2 % by weight (w/w) to 3.0 % by weight (w/w), more preferably from 1.4 % by weight (w/w) to 2.5 % by weight (w/w), and most preferably from 1.5 % by weight (w/w) to 2.2 % by weight (w/w).

14. Production plant for producing a fermented milk product comprising at least one fermentation tank for fermentation of a milk substrate using a starter culture of lactic acid bacteria at a fermentation temperature until a target pH is reached to obtain a starter culture fermented milk product and at least one heat treatment device for subjecting the starter culture fermented milk product to a heat treatment so as to reduce the level of bacteria of the starter culture to obtain a heat treated fermented milk product, wherein the plant does not comprise any device for subjecting the starter culture fermented milk product to cooling between the fermentation tank and the heating device, and wherein the plant does not comprise any means for adding a sugar-containing composition downstream of the fermentation tank. 15. Production plant according to claim 14, wherein the plant comprises between and 10 fermentation tanks.

Description:
PROCESS FOR PRODUCING A HEAT-TREATED FERMENTED MILK

PRODUCT

FIELD OF THE INVENTION

The present invention relates to a process for producing a heat-treated fermented milk product, e.g . suitable for storage at ambient temperature.

BACKGROUND OF THE INVENTION

In recent years fermented dairy products, such as yogurts, which can be stored, transported, handled and consumed in non-refrigerated conditions, i.e. at ambient temperature, for several months have become widely used . Such yogurts allow the consumer to carry the yogurt with him/her for a period of time without the need for refrigeration in the same manner as is possible for a number of beverages, and hence such yogurts provide a significant convenience advantage for the consumer. In order to obtain such a long-term shelf life at ambient temperature, the yogurt has been heat-treated after completion of the fermentation process to kill or at least inhibit further growth of the bulk of the lactic acid bacteria used in the fermentation process. The heat-treatment may e.g . be a pasteurization process or an Ultra High Temperature (UHT) process. Such yogurts are sometimes referred to as Post Pasteurized Yogurt or as Ambient Yogurt. Post Pasteurized Yogurt products contain no or only few viable lactic acid bacteria.

"Dairy Processing Handbook.com", 2015, Third Edition, published by TetraPak ® Processing Systems AB, Chapter 11, Fermented Milk Products, in the section entitled "Heat treatment of yogurt" discloses heat treatment of yogurt to prolong its shelf life. Fig . 11.22 discloses a flow chart for a process for producing heat- treated yogurt, wherein the process includes a cooling step after fermentation and before heat treatment.

"Efficacy of pasteurized yogurt in improving chronic constipation : A randomized, double-blind, placebo-controlled trial", Zhen-min Liu et al ., International Dairy Journal 40 (2015) 1-5, discloses a clinical trial testing a pasteurized yogurt sample produced in a process, wherein a milk base is homogenized, sterilized and then fermented using a starter culture containing two strains of Lb.

bulgaricus and two strains of St. thermophilus until the acidity reached 68-70 °T, and after fermentation the yogurt was immediately pasteurized.

"Effect of whey protein enrichment on selected engineering and sensory properties of Pasteurized yogurt", J. S. Alakali et al., African Journal of Food Science Vol. 5(7), pp. 392-399, April 2011, discloses a process of producing a thermized yogurt using a starter culture in the form of a mixture of

Streptococcus thermophilus, Lactobacillus bulgaricus and Lactobacillus

acidophilus. The milk base was incubated at 43-45 °C until the desired pH of 4.4 to 4.6 was reached within 4 to 5 hours, and then the yogurt coagulum was broken by manual stirring and thermized. WO2010/139765 discloses a process for producing yogurt with reduced post- acidification comprising the steps of fermentation of a milk substrate using a starter culture in the form of a weakly post-acidifying bacterial culture, maintaining the fermented milk product at the fermentation temperature for at least 30 hours and packaging the fermented milk product.

WO2015/193459 discloses a process for producing yogurt with reduced post- acidification comprising the steps of fermentation using a milk substrate with a measured amount of a carbohydrate source and a starter culture capable of metabolizing the said carbohydrate source, and terminating the fermentation by means of depletion of the carbohydrate source.

SUMMARY OF THE INVENTION

The object of the present invention is to provide an optimized process for producing a heat-treated fermented milk product.

This object is achieved by the present invention, which is directed to a process of producing a heat-treated fermented milk product comprising the steps of a) fermentation of a milk substrate using a starter culture of lactic acid bacteria at a fermentation temperature until a target pH of between 3.80 and 4.39 is reached to obtain a starter culture fermented milk product, and b) subjecting the starter culture fermented milk product to a heat treatment so as to reduce the level of bacteria of the starter culture to obtain a heat-treated fermented milk product,

- wherein step b) is carried out within a period of less than 24 hours from reaching the target pH in step a),

- wherein the starter culture fermented milk product is not subjected to cooling between step a) and b),

- wherein no sugar-containing composition is added after step a), and

- wherein the starter culture in a fermentation of a milk substrate, which contains 3.0 % protein, after reaching a target pH of 4.3 and at a temperature of 43 °C generates a post-acidification of below 0.30 pH units in 7 hours.

Up to now, industrial processes for producing heat-treated fermented milk products include as a standard a step of cooling the fermented milk product from the fermentation temperature of e.g . 43 °C to a temperature of e.g. 15 °C before the heat treatment step. The heat treatment step is conventionally carried out within a period of 1-5 hours from reaching the target pH. Such a cooling step is carried out with the object of reducing post-acidification. Also, it is believed that such a cooling step increases the texture of the fermented milk product. The present invention is based on the recognition that in a process for producing a heat-treated fermented milk product it is possible to dispense with the cooling step without risking an unacceptable level of post-acidification, because the heat-treatment will stop the fermentation process. Furthermore, the present invention is based on the surprising experimental finding that the cooling step does not increase the texture of the final heat-treated fermented milk product, but contrary to this the texture of the final heat-treated fermented milk product in fact is improved by the omission of the cooling step. Furthermore, the present invention is based on the recognition that it is possible to control the level of post-acidification during the period from reaching the target pH until heat treatment by using a starter culture, which has a low post- acidification at the target pH and at the fermentation temperature. Furthermore, the possibility of omitting the cooling step from a process for producing a heat-treated fermented milk product involves a number of significant advantages. Firstly, it is possible to save investments in equipment in the plant for production of heat-treated fermented milk. Thus, it is possible to save heat exchangers for cooling the fermented milk from e.g . 43 °C to a temperature of e.g . 15 °C and for subsequently heating the cooled fermented milk from 15 °C to a temperature of e.g . 43 °C. Also, it is possible to save one or more buffer tanks used for holding the cooled fermented milk until the heat treatment is carried out, because the fermentation tank may be used as a buffer tank for holding the fermented milk on the case where the fermented milk may be transported directly from the fermentation tank to the heat treatment step. Finally, by the said omission of equipment, space is saved in the production hall allowing a reduction in the investment of the factory building .

Secondly, the running costs for the process of producing heat-treated fermented milk may be reduced in respect to maintenance of and energy costs for running the saved equipment.

Thirdly, as mentioned above the texture of the final heat-treated fermented milk product is improved by the process of the invention, and the improvement of the texture allows a reduction in the use of additives, such as texturizing agents, e.g . protein, starch and stabilizers.

DETAILED DISCLOSURE OF THE INVENTION Overview of process steps

In a particular embodiment of the present invention, the process of the invention comprises the following sequence of treatment and holding steps : 1. Holding of ingredients of milk base in separate containers.

2. Mixing ingredients to form final milk substrate to be subjected to

fermentation .

3. Holding final milk substrate in buffer tanks, e.g . 1-3 tanks arranged in parallel and adapted for use independently of the other tanks.

4. Pasteurizing the milk substrate. 5. Inoculating the starter culture into one or more fermentation tanks.

6. Fermentation in fermentation tanks, e.g. 1-5 tanks arranged in parallel and adapted for use independently of the other tanks.

7. Optionally, holding of the starter culture fermented milk product in buffer tanks, e.g. 1-2 tanks arranged in parallel and adapted for use

independently of the other tank, before heat treatment.

8. Optionally, aseptic addition of a sugar-containing composition to the

starter culture fermented milk product before the heat treatment device.

9. Heat treatment of starter culture fermented milk substrate.

10. Holding the heat-treated fermented milk product in aseptic buffer tanks, e. g. 1-2 tanks arranged in parallel and adapted for use independently of the other tank, before aseptic filling.

11. Optionally, aseptic addition of a sugar-containing composition to the heat- treated fermented milk product before the aseptic filling device.

12. Aseptic filling of heat-treated fermented milk product.

The process of the above embodiments is particularly suitable for producing stirred fermented milk products, such as stirred yogurt. When producing set-type yogurt the fermentation and heat treatment steps are carried out in the retail container.

Fermented milk product The fermented milk product produced by the process of the invention may be any fermented milk product, which is suitable for subjecting to a heat treatment after fermentation in order to reduce level of bacteria so as to improve the shelf life of the product. Such products are often referred to as Post Pasteurized products, i.e. Post Pasteurized Yogurt (PPY), Ambient products or Extended Shelf Life (ESL) yogurt or other fermented milk products.

In a preferred embodiment of the invention, the heat-treated, fermented milk product is selected from the group consisting of set yogurt, stirred yogurt, buttermilk, sour milk, cultured milk, Smetana, sour cream, Kefir, fresh cheese and quark. In a preferred embodiment of the invention, the heat-treated fermented milk product produced by the process of the invention has a shear stress measured at 300 1/s of above 30 Pa, preferably above 35 Pa, more preferably above 40 Pa, more preferably above 45 Pa, more preferably above 50 Pa, more preferably above 55 Pa, and most preferably above 60 Pa. The shear stress of the heat- treated fermented milk product is a result i.e. of the composition of the milk substrate, the type of starter culture, the fermentation conditions, and the conditions of the heat treatment.

Starter culture

The starter culture used in the process of the invention may be any starter culture, which is capable of producing a fermented milk product, which is suitable for subjecting to a heat treatment after fermentation in order to reduce level of bacteria so as to improve the shelf life of the product

Most conventional starter cultures used for producing various types of fermented milk products are suitable for use in the process of the invention. Preferred starter cultures are those, which produce fermented milk products with high texture and/or texture, which is resistant to subsequent heat treatment.

In a preferred embodiment of the invention, the starter culture comprises one or more Lactic Acid Bacteria (LAB) strains selected from the group consisting of lactic acid bacteria strains from the order "Lactobacillales". Preferably, the starter culture comprises one or more Lactic Acid Bacteria (LAB) strains selected from the group consisting of Lactococcus spp., Streptococcus spp., Lactobacillus spp., Leuconostoc spp., Pseudoleuconostoc spp., Pediococcus spp.,

Brevibacterium spp., Enterococcus spp. and Propionibacterium spp.

In a preferred embodiment of the invention, the starter culture in a fermentation of a milk substrate, which contains 3.0 % protein, 2.8 % fat and 1.5 % modified starch, is capable of generating a starter culture fermented milk product with a shear stress measured at 300 1/s of above 50 Pa, preferably above 60 Pa, more preferably above 70 Pa, and most preferably above 80 Pa. In connection with the present invention, shear stress may be measured by the following method : The day after incubation, the fermented milk product was brought to 13°C and manually stirred gently by means of a stick fitted with a perforated disc until homogeneity of the sample. The rheological properties of the sample were assessed on a rheometer (Anton Paar Physica Rheometer with ASC, Automatic Sample Changer, Anton Paar® GmbH, Austria) by using a bob-cup. The rheometer was set to a constant temperature of 13 °C during the time of measurement. Settings were as follows :

Holding time (to rebuild to somewhat original structure)

5 minutes without any physical stress (oscillation or rotation) applied to the sample.

Oscillation step (to measure the elastic and viscous modulus, G' and G", respectively, therefore calculating the complex modulus G*)

Constant strain = 0.3 %, frequency (f) = [0.5...8] Hz

6 measuring points over 60 s (one every 10 s)

Rotation step (to measure shear stress at 300 1/s)

Two steps were designed :

1) Shear rate = [0.3-300] 1/s and 2) Shear rate = [275-0.3] 1/s.

Each step contained 21 measuring points over 210 s (on every 10 s) .

The shear stress at 300 1/s was chosen for further analysis, as this correlates to mouth thickness when swallowing a fermented milk product.

In the process of the invention, it is preferred that the starter culture has an acidification capacity so that the fermented milk product reaches a pH of 4.3 in less than 12 hours, preferably less than 10 hours, more preferably less than 9 hours, more preferably less than 8 hours, and most preferably less than 7 hours.

In the process of the invention, it is preferred that the starter culture has a low level of post-acidification at the target pH and at the fermentation temperature, since the fermented milk will be held at such conditions for a period of time until it is subjected to heat treatment. Typically, the fermented milk is held at such conditions for a period of e.g. 1-10 hours, most typically 1-5 hours.

In a preferred embodiment of the invention, the starter culture in a fermentation of a milk substrate, which contains 3.0 % protein, after reaching a target pH of 4.3 and at a temperature of 43 °C generates a post-acidification of below 0.30 pH units in 5 hours, preferably below 0.25 pH units in 5 hours, more preferably below 0.20 pH units in 5 hours, more preferably below 0.15 pH units in 5 hours, more preferably below 0.10 pH units in 5 hours, and most preferably below 0.05 pH units in 5 hours.

In a preferred embodiment of the invention, the starter culture in a fermentation of a milk substrate, which contains 3.0 % protein, after reaching a target pH of 4.3 and at a temperature of 43 °C generates a post-acidification of below 0.30 pH units in 6 hours, preferably below 0.25 pH units in 6 hours, more preferably below 0.20 pH units in 6 hours, more preferably below 0.15 pH units in 6 hours, more preferably below 0.10 pH units in 6 hours, and most preferably below 0.05 pH units in 6 hours.

In a preferred embodiment of the invention, the starter culture in a fermentation of a milk substrate, which contains 3.0 % protein, after reaching a target pH of 4.3 and at a temperature of 43 °C generates a post-acidification of below 0.30 pH units in 7 hours, preferably below 0.25 pH units in 7 hours, more preferably below 0.20 pH units in 7 hours, more preferably below 0.15 pH units in 7 hours, more preferably below 0.10 pH units in 5 hours, and most preferably below 0.05 pH units in 7 hours.

In a preferred embodiment of the invention, the starter culture in a fermentation of a milk substrate, which contains 3.0 % protein, after reaching a target pH of 4.3 and at a temperature of 43 °C generates a post-acidification of below 0.30 pH units in 8 hours, preferably below 0.25 pH units in 8 hours, more preferably below 0.20 pH units in 8 hours, more preferably below 0.15 pH units in 8 hours, more preferably below 0.10 pH units in 8 hours, and most preferably below 0.05 pH units in 8 hours. In a preferred embodiment of the invention, the starter culture in a fermentation of a milk substrate, which contains 3.0 % protein, after reaching a target pH of 4.3 and at a temperature of 43 °C generates a post-acidification of below 0.30 pH units in 9 hours, preferably below 0.25 pH units in 9 hours, more preferably below 0.20 pH units in 9 hours, more preferably below 0.15 pH units in 9 hours, more preferably below 0.10 pH units in 9 hours, and most preferably below 0.05 pH units in 9 hours.

In a preferred embodiment of the invention, the starter culture in a fermentation of a milk substrate, which contains 3.0 % protein, after reaching a target pH of 4.3 and at a temperature of 43 °C generates a post-acidification of below 0.30 pH units in 10 hours, preferably below 0.25 pH units in 10 hours, more preferably below 0.20 pH units in 10 hours, more preferably below 0.15 pH units in 10 hours, more preferably below 0.10 pH units in 10 hours, and most preferably below 0.05 pH units in 10 hours.

In a particular embodiment of the present invention, the starter culture comprises at least one lactose-deficient Streptococcus thermophilus strain and at least one Lactobacillus delbrueckii spp. bulgaricus strain.

In a particular embodiment of the invention, the starter culture contains both at least one Streptococcus thermophilus and at least one Lactobacillus delbrueckii subsp. bulgaricus, and wherein all Streptococcus thermophilus and all

Lactobacillus delbrueckii subsp. bulgaricus strains are lactose-deficient. In a particular embodiment of the present invention, the starter culture is composed of one lactose-deficient Streptococcus thermophilus strain and one Lactobacillus delbrueckii spp. bulgaricus strain.

Lactose-deficient lactic acid bacteria strains

The terms "deficiency in lactose metabolism" and "lactose deficient" are used in the context of the present invention to characterize LAB which either partially or completely lost the ability to use lactose as a source for cell growth or maintaining cell viability. Respective LAB are capable of metabolizing one or several carbohydrates selected from sucrose, galactose and/or glucose or another fermentable carbohydrate. Since these carbohydrates are not naturally present in milk in sufficient amounts to support fermentation by lactose deficient mutants, it is necessary to add these carbohydrates to the milk. Lactose deficient and partially deficient LAB can be characterized as white colonies on a medium containing lactose and X-Gal. In a particular embodiment of the invention, the lactose-deficient strain is capable of metabolizing a non-lactose carbohydrate selected from the group consisting of sucrose, galactose and glucose, preferably sucrose. In a particular embodiment of the invention, the lactose-deficient strain is capable of metabolizing galactose.

In a particular embodiment of the invention, the lactose-deficient strain is selected from the group consisting of lactose-deficient Streptococcus

thermophilus and lactose-deficient Lactobacillus delbrueckii subsp. bulgaricus. In a particular embodiment of the invention, the lactose-deficient strain is selected from the group consisting of:

(a) a Streptococcus thermophilus strain, which strain is:

(i) the strain deposited with DSMZ-Deutsche Sammlung von

Mikroorganismen und Zellkulturen GmbH, Inhoffenstr. 7B, D-38124

Braunschweig, on 2014-06-12 under the accession no. DSM 28952;

(ii) or a strain derived from DSM 28952, wherein the derived strain is further characterized as having the ability to generate white colonies on a medium containing lactose and X-Gal;

(b) a Streptococcus thermophilus strain, which strain is:

(i) the strain deposited with DSMZ-Deutsche Sammlung von

Mikroorganismen und Zellkulturen GmbH, Inhoffenstr. 7B, D-38124

Braunschweig, on 2014-06-12 under the accession no. DSM 28953;

(ii) or a strain derived from DSM 28953, wherein the derived strain is further characterized as having the ability to generate white colonies on a medium containing lactose and X-Gal;

(c) a Streptococcus thermophilus strain, which strain is:

(i) the strain deposited with DSMZ-Deutsche Sammlung von

Mikroorganismen und Zellkulturen GmbH, Inhoffenstr. 7B, D-38124

Braunschweig, on 2017-08-22 under the accession no. DSM 32599;

(ii) or a strain derived from DSM 32599, wherein the derived strain is further characterized as having the ability to generate white colonies on a medium containing lactose and X-Gal ;

(d) a Streptococcus thermophilus strain, which strain is :

(i) the strain deposited with DSMZ-Deutsche Sammlung von

Mikroorganismen und Zellkulturen GmbH, Inhoffenstr. 7B, D-38124

Braunschweig, on 2017-08-22 under the accession no . DSM 32600;

(ii) or a strain derived from DSM 32600, wherein the derived strain is further characterized as having the ability to generate white colonies on a med ium containing lactose and X-Gal ;

(e) a Lactobacillus delbrueckii ssp . bulgaricus strain, which strain is :

(i) the strain deposited with DSMZ-Deutsche Sammlung von

Mikroorganismen und Zellkulturen GmbH, Inhoffenstr. 7B, D-38124

Braunschweig, on 2014-06- 12 under the accession no. DSM 28910;

(ii) or a strain derived from DSM 28910, wherein the derived strain is further characterized as having the ability to generate white colonies on a medium containing lactose and X-Gal .

Milk substrate In a preferred embod iment of the invention, the milk substrate used in the process of the invention contains a texturizing agent, such as a thickener and a stabilizer. Preferably, the texturizing agent is selected from the group consisting of starch, modified starch, gellan gum, pectin, alginate, agar agar, guar gum, Locust Bean Gum (LBG, carob g um), carrageenan, gelatin and Whey Proteins, e.g . Whey Protein Concentrate (WPC) .

In a preferred embodiment of the invention, the milk substrate used in the process of the invention contains between 1 and 5 texturizing agents, preferably between 2 and 4 texturizing agents. Preferably, the milk substrate contains texturizing agents in a total amount of from 0,5 % by weig ht (w/w) to 5.0 % by weight (w/w), more preferably from 1.0 % by weig ht (w/w) to 4.0 % by weight (w/w), more preferably from 1.2 % by weight (w/w) to 3.0 % by weight (w/w), more preferably from 1.4 % by weight (w/w) to 2.5 % by weight (w/w), and most preferably from 1.5 % by weight (w/w) to 2.2 % by weig ht (w/w) . In a preferred embodiment of the invention, the milk substrate used in the process of the invention contains added sucrose in an amount of from 1 % by weight (w/w) to 13.0 % by weight (w/w), more preferably from 2.0 % by weight (w/w) to 12.0 % by weight (w/w), more preferably from 3.0 % by weight (w/w) to 11.0 % by weight (w/w) more preferably from 4.0 % by weight (w/w) to 10.0 % by weight (w/w), more preferably from 5.0 % by weight (w/w) to 9.0 % by weight (w/w), and most preferably from 6.0 % by weight (w/w) to 8.0 % by weight (w/w) . In a preferred embodiment of the invention, the milk substrate used for the fermentation with the starter culture contains a sugar-containing composition . Preferably, the sugar-containing composition is selected from the group consisting of an artificial sugar; a High Intensity Natural Sweetener; and a sugar syrup, a puree, a juice and a nectar obtained from a source selected from the group consisting of a fruit, a vegetable and a grain . Preferably, the sugar syrup is selected from the group consisting of maple syrup, a corn syrup, a glucose syrup, a high-fructose corn syrup and golden syrup.

In connection with the present invention the term "sugar" means a natural saccharide selected from the group consisting of fructose, glucose, sucrose and mixtures thereof, an artificial sugar or a High Intensity Natural Sweetener.

Preferably, the High Intensity Natural Sweetener is a steviol glycoside, incl . stevia. Preferably, the artificial sugar is a High Intensity Artificial Sweetener selected from the group consisting aspartame, sucralose, neotame, acesulfame potassium, saccharin, advantame and cyclamates.

Most commercial heat-treated fermented milk products contain an added sugar- containing composition, such as a sugar syrup or a fruit puree. Addition of the sugar-containing composition together with the other ingredients of the milk substrate has the advantage that an additional, separate step of addition of the sugar-containing composition may be avoided . Also, when the sugar-containing composition is added to the fermented milk product after the fermentation step or after the heat treatment step, the sugar-containing composition should itself be heat-treated or sterilized, and it should furthermore be added to the fermented milk product in an aseptic step, which is expensive and difficult to carry out. Therefore, addition of the sugar-containing composition the before fermentation step is preferred. In a preferred embodiment of the invention, the milk substrate used for the fermentation with the starter culture has a protein content of between 1 % by weight (w/w) and 8.0 % by weight (w/w), preferably between 1.2 % by weight (w/w) and 7.0 % by weight (w/w), more preferably between 1.4 % by weight (w/w) and 6.0 % by weight (w/w) preferably between 1.6 % by weight (w/w) and 5.0 % by weight (w/w), preferably between 1.8 % by weight (w/w) and 4.5 % by weight (w/w), and most preferably between 2.0 % by weight (w/w) and 4.0 % by weight (w/w).

In a preferred embodiment of the invention, the milk substrate used for the fermentation with the starter culture has a fat content of between 1 % by weight (w/w) and 8.0 % by weight (w/w), preferably between 1.2 % by weight (w/w) and 7.0 % by weight (w/w), more preferably between 1.4 % by weight (w/w) and 6.0 % by weight (w/w) preferably between 1.6 % by weight (w/w) and 5.0 % by weight (w/w), preferably between 1.8 % by weight (w/w) and 4.5 % by weight (w/w), and most preferably between 2.0 % by weight (w/w) and 4.0 % by weight (w/w).

In a preferred embodiment of the invention, the milk substrate used for the fermentation with the starter culture contains an additive selected from the group consisting of a grain; and a puree, a juice and a nectar obtained from a source selected from the group consisting of a fruit, a vegetable and a grain. The grain may e.g. be in the form of a grain flour.

Fermentation step

In a preferred embodiment of the process of the invention the target pH is from 3.80 to 4.39, preferably from 3.80 to 4.38, more preferably from 3.80 to 4.37, more preferably from 3.80 to 4.36, more preferably from 3.80 to 4.35, more preferably from 3.80 to 4.34, more preferably from 3.80 to 4.33, more preferably from 3.80 to 4.32, more preferably from 3.80 to 4.31, more preferably from 3.80 to 4.30, more preferably from 3.90 to 4.30, and most preferably from 4.00 to 4.30.

In general it is preferred that fermented milk products have a pH of below 3.90 for reasons of food safety, in particular to prevent growth of pathogenic microorganisms. On the other hand it is preferred that fermented milk products have a pH of above 4.00 for reasons of flavor and taste.

In a particular embodiment of the process of the invention, the starter culture fermented milk produced in step a) is transported directly from step a) to the heat treatment step b). Herein, the term "transported directly" means transport through a pipe without passing through any treatment device or tank.

In conventional processes for producing heat-treated fermented milk products including a cooling step after the fermentation step, the cooled fermented milk product is transported to a buffer tank, in which it is held for a period of time before transport to the heat treatment step in order to align the capacity of the cooling step to that of the heat treatment step. The present process has provided a possibility of transporting the starter culture fermented milk directly from the fermentation step to the heat treatment step b), and this in turn has provided a possibility of omitting the use of an intermediate buffer tank by using the fermentation tank itself as a buffer tank.

In an alternative particular embodiment of the process of the invention, the starter culture fermented milk produced in step a) is transported from step a) to a buffer tank, from which it is transported to the heat treatment step b).

In a preferred embodiment of the process of the invention, step b) is carried out within a period of less than 20 hours, preferably 15 hours, more preferably 10 hours, more preferably 7 hours, more preferably 5 hours from reaching the target pH in step a).

In a preferred embodiment of the invention, the curd of the starter culture fermented milk product formed in step a) is broken, e.g. by stirring, before subjecting it to heat treatment in step b). Heat treatment

In a preferred embodiment of the invention, the starter culture fermented milk product is subjected to a heat treatment so as to reduce the level of bacteria of the starter culture to no more than 1.0X10exp02 CFU per g fermented milk. Preferably, the level of bacteria of the starter culture is reduced to no more than l .OXlOexpOl CFU per g fermented milk, more preferably 0 CFU per g . The heat treatment is preferably carried out by subjecting the starter culture fermented milk product to a temperature of between 50 °C and 105 °C, preferably between 50 °C and 90 °C, more preferably between 60 °C and 85 °C, more preferably between 65 °C and 82 °C, and most preferably between 70 °C and 80 °C. The heat treatment is preferably carried out for a period of between 10 seconds and 180 seconds, preferably between 12 seconds and 120 seconds, more preferably between 14 seconds and 90 seconds, more preferably between 16 seconds and 60 seconds, more preferably between 18 seconds and 50 seconds and most preferably between 20 and 40 seconds. The heat-treatment may e.g. be a pasteurization process or an Ultra High Temperature (UHT) process.

Production plant for producing fermented milk product The present invention further relates to a production plant for producing a fermented milk product comprising at least one fermentation tank for fermentation of a milk substrate using a starter culture of lactic acid bacteria at a fermentation temperature until a target pH is reached to obtain a starter culture fermented milk product and at least one heat treatment device for subjecting the starter culture fermented milk product to a heat treatment so as to reduce the level of bacteria of the starter culture to obtain a heat treated fermented milk product, wherein the plant does not comprise any device for subjecting the starter culture fermented milk product to cooling between the fermentation tank and the heating device, and wherein the plant does not comprise any means for adding a sugar-containing composition downstream of the fermentation tank.

In a preferred embodiment of the plant of the invention, the plant comprises between 1 and 10, preferably between 2 and 8, more preferably between 3 and 7 fermentation tanks.

In a preferred embodiment of the plant of the invention, the heat treatment device is selected from the group consisting of a plate heat exchanger and a tubular heat exchanger. Preferably, the heat treatment device is a plate heat exchanger.

In a particular embodiment of the present invention, the production plant comprises the following sequence of treatment and holding equipment: 1. Containers for separate holding ingredients of milk base.

2. Equipment for mixing ingredients to form final milk substrate to be

subjected to fermentation.

3. Buffer tanks, e.g. 1-3 tanks arranged in parallel and adapted for use

independently of the other tanks, for holding final milk substrate.

4. Milk substrate pasteurizer, e.g . plate heat exchanger.

5. Means for inoculating the starter culture into individual fermentation tank separately.

6. Fermentation tanks, e.g. 1-5 tanks arranged in parallel and adapted for use independently of the other tanks.

7. Optionally, buffer tanks, e.g. 1-2 tanks arranged in parallel and adapted for use independently of the other tank, for holding the starter culture fermented milk product before heat treatment.

8. Optionally, equipment for aseptic addition of a sugar-containing

composition to the starter culture fermented milk product before the heat treatment device.

9. Heat treatment device (yogurt pasteurizer), e.g. a plate heat exchanger or a tubular heat exchanger.

10. Aseptic buffer tanks, e. g. 1-2 tanks arranged in parallel and adapted for use independently of the other tank, for holding the heat-treated fermented milk product before aseptic filling. 11. Optionally, equipment for aseptic addition of a sugar-containing composition to the heat-treated fermented milk product before the aseptic filling eq uipment.

12. Aseptic filling equipment for filling the heat-treated fermented milk

product into retail containers.

DEFINITIONS

In connection with the present invention the terms and expressions listed below have the following meaning :

The expression "heat treatment" means any treatment using any temperature, for any period of time and by any means or equipment, which inactivates at least a portion of the bacteria of the starter culture. In this connection the term "inactivate" means any stop, reduction or inhibition of growth of the bacteria, e.g . cell lysing .

The expression "ambient storage" means suitable for being stored at ambient temperature for a long time, at least 150 days. The expression "ambient temperature" means the temperature of the surround ings, e.g . room

temperature. For example, the ambient temperature may be between 5 °C and 40 °C, more particularly between 10 °C and 35 °C, more particularly between 15 °C and 30 °C, and most particularly between 18 °C and 27 °C. The expression "starter culture fermented milk product" means a fermented milk prod uct, which contains the starter culture used to ferment the milk.

The expression "heat treated fermented milk prod uct" means a fermented milk product, which has been subjected to heat treatment.

The expression "lactic acid bacteria" designates a gram-positive, microaerophilic or anaerobic bacterium, which ferments sugars with the production of acids including lactic acid as the predominantly produced acid, acetic acid and propionic acid . The industrially most useful lactic acid bacteria are found within the order "Lactobacillales" which includes Lactococcus spp., Streptococcus spp., Lactobacillus spp., Leuconostoc spp., Pseudoleuconostoc spp., Pediococcus spp., Brevibacterium spp., Enterococcus spp. and Propionibacterium spp. These are frequently used as food cultures alone or in combination with other lactic acid bacteria.

Lactic acid bacteria, including bacteria of the species Lactobacillus sp. and Lactococcus sp., are normally supplied to the dairy industry either as frozen or freeze-dried cultures for bulk starter propagation or as so-called "Direct Vat Set" (DVS) cultures, intended for direct inoculation into a fermentation vessel or vat for the production of a dairy product, such as a fermented milk product or a cheese. Such lactic acid bacterial cultures are in general referred to as "starter cultures" or "starters".

The term "milk" is to be understood as the lacteal secretion obtained by milking of any mammal, such as cows, sheep, goats, buffaloes or camels. In a preferred embodiment, the milk is cow's milk. The term milk also includes protein/fat solutions made of plant materials, e.g. soy milk and grain milk, including oat milk and wheat milk. The term "milk substrate" may be any raw and/or processed milk material that can be subjected to fermentation according to the method of the invention. Thus, useful milk substrates include, but are not limited to, solutions/- suspensions of any milk or milk like products comprising protein, such as whole or low fat milk, skim milk, buttermilk, reconstituted milk powder, condensed milk, dried milk, whey, whey permeate, lactose, mother liquid from

crystallization of lactose, whey protein concentrate, or cream. Obviously, the milk substrate may originate from any mammal, e.g. being substantially pure mammalian milk, or reconstituted milk powder. Prior to fermentation, the milk substrate may be homogenized and pasteurized according to methods known in the art.

"Homogenizing" as used herein means intensive mixing to obtain a soluble suspension or emulsion. If homogenization is performed prior to fermentation, it may be performed so as to break up the milk fat into smaller sizes so that it no longer separates from the milk. This may be accomplished by forcing the milk at high pressure through small orifices.

"Pasteurizing" and "thermization" as used herein means treatment of the milk substrate to reduce or eliminate the presence of live organisms, such as microorganisms. Preferably, pasteurization is attained by maintaining a specified temperature for a specified period of time. The specified temperature is usually attained by heating. The temperature and duration may be selected in order to kill or inactivate certain bacteria, such as harmful bacteria. A rapid cooling step may follow.

"Fermentation" in the methods of the present invention means the conversion of carbohydrates into alcohols or acids through the action of a microorganism. Preferably, fermentation in the methods of the invention comprises conversion of lactose to lactic acid.

Fermentation processes to be used in production of dairy products are well known and the person of skill in the art will know how to select suitable process conditions, such as temperature, oxygen, amount and characteristics of microorganism(s) and process time. Obviously, fermentation conditions are selected so as to support the achievement of the present invention, i.e. to obtain a dairy product in solid (such as a cheese) or liquid form (such as a fermented milk product). The use of the terms "a" and "an" and "the" and similar referents in the context of describing the invention (especially in the context of the following claims) are to be construed to cover both the singular and the plural, unless otherwise indicated herein or clearly contradicted by context. The terms "comprising", "having", "including" and "containing" are to be construed as open-ended terms (i.e., meaning "including, but not limited to,") unless otherwise noted. Recitation of ranges of values herein are merely intended to serve as a shorthand method of referring individually to each separate value falling within the range, unless otherwise indicated herein, and each separate value is incorporated into the specification as if it were individually recited herein. All methods described herein can be performed in any suitable order unless otherwise indicated herein or otherwise clearly contradicted by context. The use of any and all examples, or exemplary language (e.g ., "such as") provided herein, is intended merely to better illuminate the invention and does not pose a limitation on the scope of the invention unless otherwise claimed . No language in the specification should be construed as indicating any non-claimed element as essential to the practice of the invention .

The expression "fermented milk product" means a food or feed product wherein the preparation of the food or feed product involves fermentation of a milk substrate with a lactic acid bacteria. "Fermented milk product" as used herein includes but is not limited to products such as thermophilic fermented milk products, e.g . yogurt, mesophilic fermented milk products, e.g . sour cream and buttermilk, cheese as well as fermented whey. The term "thermophile" herein refers to microorganisms that thrive best at temperatures above 43°C. The industrially most useful thermophilic bacteria include Streptococcus spp. and Lactobacillus spp. The term "thermophilic fermentation" herein refers to fermentation at a temperature above about 35°C, such as between about 35°C to about 45°C. The term "thermophilic fermented milk product" refers to fermented milk products prepared by thermophilic fermentation of a thermophilic starter culture and include such fermented milk products as set-yogurt and stirred-yogurt.

The term "mesophile" herein refers to microorganisms that thrive best at moderate temperatures (15°C-40°C) . The industrially most useful mesophilic bacteria include Lactococcus spp. and Leuconostoc spp. The term "mesophilic fermentation" herein refers to fermentation at a temperature between about 22°C and about 35°C. The term "mesophilic fermented milk product" refers to fermented milk products prepared by mesophilic fermentation of a mesophilic starter culture and include such fermented milk products as buttermilk, sour milk, cultured milk, smetana, sour cream, Kefir and fresh cheese, such as quark.

In the present context the term "fruit juice" refers to the liquid naturally contained in fruit prepared by mechanically squeezing or macerating fresh fruits without the presence of heat and solvents. The "fruit juice" may consist of juice from one type of fruit or a mixture of more than one type of fruit. The "fruit juice" may be either one containing pulp, or one from which the pulp has been removed by such an operation as centrifugation . The term "nectar" in the present context refers to a beverage having a fruit juice content of between 30 to 99% fruit juice.

In the present context the term "puree" refers to fruits prepared by ground ing, pressing and/or straining into the consistency of a thick liq uid or a soft paste without the presence of heat and solvents. "Puree" is made of 100% fruit as opposed to being made from just the juice of the fruit.

The term "adding aseptically" means without introducing or introducing a minimum of any microorganism other than the ambient storage lactic acid bacteria .

The term "target pH" means the pH at which the fermentation is deemed to be finished, and from the point in time at which the target pH is reached the starter culture fermented milk product is ready for further processing, e.g . heat treatment.

The term "grain" means any product obtained from a cereal or g rain biological source material, including oat, corn, barley, rye, buckwheat, wheat and rice. The expression "X.XxlOexpYY" and "X.XEYY", both mean X.Xxl0 YY , and the two said expressions are used interchangeably.

The expression "CFU" means Colony Forming U nits. FIGURES

Fig . 1 shows acid ification profiles for four commercial Chr. Hansen YoFlex® cultures at 43 °C for 24 hours. Fig . 2 shows acid ification profiles for four commercial Chr. Hansen YoFlex' cultures at 43 °C after a pH of 4.3 has been reached.

DEPOSITS AND EXPERT SOLUTION The Applicant requests that a sample of the deposited microorganism should be made available only to an expert approved by the Applicant.

Streptococcus thermophilus strain deposited with DSMZ-Deutsche Sammlung von Mikroorganismen und Zellkulturen GmbH, Inhoffenstr. 7B, D-38124 Braunschweig, on 2014-06-12 under the accession no. DSM 28952.

Streptococcus thermophilus strain deposited with DSMZ-Deutsche Sammlung von Mikroorganismen und Zellkulturen GmbH, Inhoffenstr. 7B, D-38124 Braunschweig, on 2014-06-12 under the accession no. DSM 28953.

Streptococcus thermophilus strain deposited with DSMZ-Deutsche Sammlung von Mikroorganismen und Zellkulturen GmbH, Inhoffenstr. 7B, D-38124 Braunschweig, on 2017-08-22 under the accession no. DSM 32599. Streptococcus thermophilus strain deposited with DSMZ-Deutsche Sammlung von Mikroorganismen und Zellkulturen GmbH, Inhoffenstr. 7B, D-38124 Braunschweig, on 2017-08-22 under the accession no. DSM 32600.

Lactobacillus delbrueckii ssp. bulgaricus deposited with DSMZ-Deutsche Sammlung von Mikroorganismen und Zellkulturen GmbH, Inhoffenstr. 7B, D- 38124 Braunschweig, on 2014-06-12 under the accession no. DSM 28910.

The deposits were made according to the Budapest treaty on the international recognition of the deposit of microorganisms for the purposes of patent procedure.

EXAMPLES

Example 1: Comparison of process for producing heat-treated yogurt using a cooling step with a process using no cooling step The purpose of the experimental work carried out was to show that heat-treated yogurt produced by a process with no cooling step after fermentation and before heat treatment has improved texture.

Post pasteurized yogurt with a composition of 3.0% protein and 2.8% fat was produced . The milk substrate was fermented to pH of 4.30 with Starter culture 2 from Chr. Hansen YoFlex® product range. The batch produced was further divided into three batches of post pasteurized yogurt. One of the batches was heat treated at 74°C for 20s directly from the fermentation tank where the temperature was 43°C. The other two batches where cooled down to 15°C and 25°C respectively in a plate heat exchanger and kept in insulated buffer tanks at respective temperature for three hours before performing the final heat treatment (74°C, 20s.). The final heat treatment was done in a plate heat exchanger for all three batches, and the product was filled at 25°C into sterile beakers. The samples were stored ambient (25°C) for one week prior to evaluating the texture.

Milk substrate

Milkoscan analysis: Fat level 2.8% Protein level 3.0%

The following parameters were used for fermentation and processing :

Mixing temperature : 10°C

Hydration time: 3 hours with gentle stirring Starter culture

Starter culture 2 from Chr. Hansen YoFlex® product range containing the two species Streptococcus thermophilus and Lactobacillus delbrueckii spp. bulgaricus.

Measurement of shear stress (correlated to mouth thickness ' )

The samples were tempered to be 13°C for one hour prior to shear stress measurements. Stirring with spoon was applied to give a homogenous sample, i.e. stirring five times. Measurement was conducted at 13°C in an Anton Paar autosampler with a bob-cup method, where the cup was 32mm and bob 25mm. The shear rate went up to 300 1/s and the duration was 210s. The shear stress result has previously been correlated to mouth thickness when swallowing, scoring in a trained sensory panel.

Compression test (correlated to gel firmness on a spoon as evaluated by a trained sensory panel) A back extrusion test was conducted to evaluate gel firmness. The samples were tempered to be 13°C for one hour prior to shear stress measurements. Stirring with spoon was applied to give a homogenous sample, i.e. stirring five times. Measurement was done by TA-XT plus, software Texture Expert Exceed v6.1.9.0. A cylindrical acrylic probe (0 40mm) penetrated the yogurt to a depth of 15mm with a speed of 2mm/s and a trigger force of 5g . The positive area was used as firmness measurement.

Process for producing yogurt Homogenization pressure : 150 bar

Pasteurization condition : 95°C, 5 minutes

Fermentation temperature: 43°C

End pH : 4.30

Break the curd manually and stir until smooth structure is obtained .

For batches cooled down : Cooling to 15°C and 25°C in Plate heat exchanger Thermization in plate heat exchanger, flow 414L/h

Homogenization pressure : 0 bar

Thermization condition : 74°C, 20s

Filling into sterile 100 ml cups, filling temperature 25°C.

Results

In Table 1 results of shear stress measurements, correlated to mouth thickness of the three samples are shown . The results of compression test measurements, correlated to gel firmness is shown in Table 2 for the same three samples. The texture data of the three samples clearly show the benefit by bypassing the cooling step prior to the final heat treatment.

Table 1 : Shear stress measurements (correlated to mouth thickness) of th samples.

Acidification profiles of four commercial Chr. Hansen YoFlex ® cultures

Experimental work has been carried out to evaluate the acidification

performance of four Chr. Hansen YoFlex® range cultures : Starter culture 1, 2, 3 and 4. The four cultures was inoculated to milk with a composition of 3.0% protein, 2.8% fat and the fermentation at 43°C was recorded with Cinac system for 24 hours after inoculation, see Figure 1. Furthermore the acidification from pH 4.3 and below is shown in Figure 2. The acidification data, illustrating in- process post-acidification, show that the four cultures all had low levels of post- acidification at 43 °C. As will appear from Fig . 2, after reaching a pH of 4.3, the pH over a period of 5 hours decreases to pH 4.18, 4.15, 4.03, 3.96 for the starter cultures 1, 2, 3 and 4, respectively, acidification at 43 °C. As will appear from Fig. 2, after reaching a pH of 4.3, the pH over a period of 10 hours decreases to pH 4.13, 4.08, 3.94, 3.83 for the starter cultures 1, 2, 3 and 4, respectively. As will appear from Fig. 2, after reaching a pH of 4.3, the pH over a period of 7 hours decreases to pH 4.16, 4.11, 3.99, 3.89 for the starter cultures 1, 2, 3 and 4, respectively. The experiment shows that commercial cultures exist, which are suitable for use in a process of producing heat-treated yogurt with no cooling step between fermentation and heat treatment.

Example 2: Comparison of process for producing heat-treated yogurt using a cooling step with a process using no cooling step (30 L and 300 L scale)

The purpose of the experimental work carried out was to show that heat-treated yogurt produced by a process with no cooling step after fermentation and before heat treatment has improved texture as compared to a process with a cooling step.

Post pasteurized yogurt was produced. The milk substrate was fermented at 43°C to pH of 4.30 with Starter Culture 1 from Chr. Hansen YoFlex® product range in both 30 L scale and in 300 L scale.

For the 30 L scale one sample was heat treated at 74°C for 20s directly from the fermentation tank, and two samples were cooled down to 15°C and 25 °C in a plate heat exchanger and kept in insulated buffer tanks at respective

temperature for three hours before performing the final heat treatment (74°C, 20s.)- For the 300 L scale one sample was heat treated at 74°C for 20s directly from the fermentation tank, and two samples were cooled down to 15°C and 25 °C in a plate heat exchanger and kept in insulated buffer tanks at respective temperature for three hours, and one sample was maintained at 43°C for five hours before performing the final heat treatment (74°C, 20s.).

The final heat treatment was done in a plate heat exchanger for all samples, and the product was filled into sterile beakers. Milk substrate

Milkoscan of milk substrate:

Protein : 2.85 %

Fat: 2.88 %

Starter culture

Starter culture 1 from Chr. Hansen YoFlex® product range containing the two species Streptococcus thermophilus and Lactobacillus delbrueckii spp. bulgaricus.

Measurement of shear stress (correlated to mouth thickness)

Measurement was carried out as indicated in Example 1. Compression test (correlated to gel firmness on a spoon as evaluated by a trained sensory panel) Measurement was carried out as indicated in Example 1.

Process for producing yogurt

Homogenization pressure : 150 bar

Pasteurization condition : 95°C, 5 minutes

Fermentation temperature: 43°C

End pH : 4.30

Break the curd manually and stir until smooth structure is obtained .

For batches cooled down : Cooling to 13°C in Plate heat exchanger

Thermization condition : 74°C, 20s

Filling into sterile cups.

Results In Table 3 results of shear stress measurements, correlated to mouth thickness of the three samples are shown. The results of compression test measurements, correlated to gel firmness is shown in Table 4 for the same three samples. The texture data of the three samples clearly show the benefit by bypassing the cooling step prior to the final heat treatment.

Table 3 : Shear stress measurements (correlated to mouth thickness)

*Air in cup

As will appear from Tables 3 and 4, the texture results of the present

experiment clearly show the benefit of bypassing the cooling step prior to the final heat treatment in a process for producing post-pasteurized yogurt.

Example 3: Comparison of process for producing heat-treated yogurt using a cooling step with a process using no cooling step

Experiment design

The purpose of this experiment is to test the effect of cooling on product rheology. Trials were conducted for 2 different level of starch. For each level of starch, one half of the yogurt will be thermized immediately after achieving end pH. Another half of the yogurt will be cooled down to 20 °C in a Post Treatment Unit (PTU) (without any pressure), and the yogurt is then stored at 20 °C for 4 hours before thermization. A yogurt starter culture composed of a mixture of one lactose-deficient Streptococcus thermophilus strain and one Lactobacillus delbrueckii spp. bulgaricus strain was chosen in order to study exclusively the effect of cooling of the yogurt to 20 °C before thermization on the texture, hence avoiding the bias of any post acidification during the 4 hours of storage at 20 °C.

Table 5 : Composition of milk base

Process

Milk base and fermentation Mixing : Silverson Mixer

Mixing temperature: Cold mixing at 10 °C - 15 °C

Hydration time: 2 hours minimum

Process: GEA pilot plant

• Homogenization temperature: 65 °C

• Homogenization pressure: 200 bar + 50 bar (total 250 bar) • pasteurization condition : 95 °C /5 min

• cooling temperature: less than 15 °C

• heat up using the bucket pasteurizing unit (BPU) before fermentation the next day

Fermentation : Scandinox BPU

• Fermentation temperature: 43 °C

• End pH : 4.30 - 4.35

Post Treatment/Thermization of Yogurt

Break the curd manually when end pH achieve.

Thermize the yogurt through GEA pilot plant connected to a smoothing machine:

• Thermization condition : 75 °C /20s

• Smoothing : speed 1 (5 m/s) - Shear = 11 100 s-1

Filling into bottles (filling temperature: 24 °C - 28 °C)

Measurements

Instrument: Anton Paar Modular Compact Rheometer MCR 302

Measuring temperature: 20 °C

Program : Oscillation and Hysteresis Curve

5 extracts from rheometer hysteresis curve:

Viscosity pt. 1 : initial state

Viscosity pt. 5 : Viscosity at 60 s-1 (correlates well with texture in mouth) Viscosity pt. 10 : Viscosity at 135 s-1

Viscosity pt. 21 : cohesiveness (difficulty to swallow)

Area : resistance to shear, ropiness Results Rheology Table 6 : Rheology at day 7 after end of fermentation

As will appear from Table 6, both samples produced in a process with no cooling have a significantly improved rheology as compared to the corresponding samples produced in a process with a cooling step. Also, the samples produced from a milk base with a high content of starch have an improved rheology as compared to the corresponding samples produced from a milk base with a low content of starch . Finally, the results show that the pH of the samples with no cooling and the pH of the samples with 4 hours of cooling are precisely the same, which means that no post-acidification have occurred with the starter culture used (composed of lactose-deficient strains) .