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Title:
BAKING COMPOSITION COMPRISING LACTOBACILLUS CRUSTORUM STRAIN
Document Type and Number:
WIPO Patent Application WO/2019/091547
Kind Code:
A1
Abstract:
The present invention belongs to the technical field of food processing. More specifically, the present invention relates to baking compositions comprising a deposited Lactobacillus crustorum strain for preparing bakery products. Sourdough products including steamed bun products are disclosed.

Inventors:
HUANG, Weining (No 1800 Lihu Avenue, Wuxi, Jiangsu 2, 214122, CN)
TANG, Xiaojuan (No 1800 Lihu Avenue, Wuxi, Jiangsu 2, 214122, CN)
JIA, Chunli (No 1800 Lihu Avenue, Wuxi, Jiangsu 2, 214122, CN)
LI, Ning (1901, Building 12 Dong Hai Hua Yuan, 18 Yingbin Road Panyu Distric, Guangzhou Guangdong, CN)
ARNAUT, Filip (Weverstraat 58, 1761 Roosdaal, 1761, BE)
Application Number:
EP2017/078475
Publication Date:
May 16, 2019
Filing Date:
November 07, 2017
Export Citation:
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Assignee:
JIANGNAN UNIVERSITY (No 1800 Lihu Avenue, Wuxi, Jiangsu 2, 214122, CN)
PURATOS NV (Industrialaan 25, 1702 Groot-Bijgaarden, 1702, BE)
International Classes:
A21D8/04; A21D10/00; A21D13/40; C12R1/225
Foreign References:
EP3202893A12017-08-09
Other References:
FRDRIC RAVYTS ET AL: "Prevalence and impact of single-strain starter cultures of lactic acid bacteria on metabolite formation in sourdough", FOOD MICROBIOLOGY, ACADEMIC PRESS LTD, LONDON, GB, vol. 28, no. 6, 5 March 2011 (2011-03-05), pages 1129 - 1139, XP028377747, ISSN: 0740-0020, [retrieved on 20110311], DOI: 10.1016/J.FM.2011.03.004
DATABASE FSTA [online] INTERNATIONAL FOOD INFORMATION SERVICE (IFIS), FRANkFURT-MAIN, DE; August 2017 (2017-08-01), XUE-TING WANG ET AL: "Screening and identification of the dominant bacteria from Chinese traditional sour doughs and application in tartary buckwheat bran steamed bread.", XP002776581, Database accession no. FS-2017-08-Mn3973
OMEDI JACOB OJOBI ET AL: "Effect of five lactic acid bacteria starter type on angiotensin-I converting enzyme inhibitory activity and emulsifying properties of soy flour sourdoughs with and without wheat bran supplementation", JOURNAL OF CEREAL SCIENCE, ACADEMIC PRESS LTD, GB, vol. 69, 20 February 2016 (2016-02-20), pages 57 - 63, XP029559061, ISSN: 0733-5210, DOI: 10.1016/J.JCS.2016.02.008
I. SCHEIRLINCK ET AL: "Lactobacillus crustorum sp. nov., isolated from two traditional Belgian wheat sourdoughs", INTERNATIONAL JOURNAL OF SYSTEMATIC AND EVOLUTIONARY MICROBIOLOGY, vol. 57, no. 7, 1 July 2007 (2007-07-01), GB, pages 1461 - 1467, XP055434024, ISSN: 1466-5026, DOI: 10.1099/ijs.0.64836-0
None
Attorney, Agent or Firm:
DE CLERCQ & PARTNERS (Edgard Gevaertdreef 10a, 9830 Sint-Martens-Latem, 9830, BE)
Download PDF:
Claims:
CLAIMS

1 . A Lactobacillus crustorum strain as deposited under the accession number LMG P- 29154 at the BCCM/LMG culture collection, or variants thereof.

2. A baking composition for use in the preparation of bakery products comprising a strain according to claim 1 .

3. Baking composition according to claim 2, wherein said baking composition is chosen form a starter culture for bakery products, a sourdough or a sourdough product.

4. Baking composition according to claim 2 or 3, further comprising one or more strains of lactic acid bacteria and/or one or more strains of yeast.

5. Baking composition according to claim 4, wherein said one or more strains of lactic acid bacteria are chosen from acid forming bacteria such as Leuconostoc or Lactobacillus, and/or wherein said one or more strains of yeast are chosen from Saccharomyces, Candida, Pichia, Kluyveromyces or Hansenula strains.

6. Baking composition according to claim 4 or 5, wherein said one or more strains of lactic acid bacteria are chosen from Lactobacillus plantarum, Lactobacillus brevis,

Lactobacillus sanfrancisciensis and/or Lactobacillus reuterii, and/or wherein said one or more strains of yeast are chosen from Saccharomyces cerevisiae and Saccharomyces exiguus.

7. Baking composition according to any of claims 2 to 6, wherein said baking composition is a sourdough or a sourdough product.

8. Baking composition according to claim 7, wherein said baking composition further comprises cereal or cereal fractions, and optionally sugar and/or minerals.

9. Baking composition according to claim 7 or 8, wherein said baking composition is fermented by at least a strain of Lactobacillus crustorum according to claim 1 .

10. Baking composition according to any of claims 7 to 9, wherein said baking composition is an active or inactive sourdough or sourdough product.

1 1 . Baking composition according to any of claims 2 to 6, wherein said baking composition is a starter culture.

12. A method for preparing a sourdough or a sourdough product according to any of claims 7 to 10 comprising the steps of: fermenting a (liquid) mixture comprising cereal and/or cereal fractions, and a liquid, preferably water, with at least one strain of Lactobacillus crustorum LMG p-29154, thereby obtaining the (liquid) sourdough; and

optionally drying said (liquid) sourdough thereby obtaining a dried composition.

13. Use of a baking composition according to any of claims 2 to 1 1 in the preparation of a food product.

14. Bakery product comprising a baking composition according to any of claims 2 to 1 1.

15. Bakery product according to claim 14 which is a steamed bun.

Description:
BAKING COMPOSITION COMPRISING

LACTOBACILLUS CRUSTORUM STRAIN

FIELD OF THE INVENTION

The present invention belongs to the technical field of food processing. More specifically, the present invention relates to baking compositions comprising a Lactobacillus crustorum strain for preparing bakery products.

BACKGROUND OF THE INVENTION

Bread (including Asian-type steamed bread) is a traditional staple food, with distinctive ethnic characteristics. Today, there are two main types of bread fermentation. The first is the fermentation of flour by commercial yeast. It is a simple way of making bread and not very time-consuming, but the flavour is generally poor or neutral. A more traditional type is the bread obtained using pre-doughs (such as sourdough or sponge) as leavening agent. Sourdoughs are restarted using a part of the previous fermented dough which is therefore constantly renewed in a cyclical way, using specific recipes and ripening conditions. The mother dough is then mixed with the rest of the flour, the water and the other dough ingredients to a suitable consistency, and then given a short period for bulk fermentation before final proofing and baking. The breads or steamed breads obtained using this method are richer in flavour and have a higher nutritional value. However this method is time consuming and the quality of the sourdough may be inconsistent, varying in time.

Alternative methods exist that provide sourdoughs with desired characteristics and constant quality. Two types of products may be considered:

"Ready to use active sourdoughs" are improved types of sourdoughs using adapted strains or liquid sourdough starters to start the fermentation. These sourdoughs can be pasty or liquid and are generally stable and easy to process for example in an automated bakery. There are enough living lactic acid bacteria and/or yeast to ferment the bread dough successfully or to initiate a multiple stage sourdough process.

"Ready to use inactive powder or liquid sourdoughs" are used by traditional or industrial bakeries for their convenience since the quality is constant and they are easy to use. They deliver the acidity and the conventional sourdough flavour directly avoiding a long fermentation step. Furthermore one or several specific microbial strains may be produced, conditioned (for example as a dried starter) and provided to the baker so that he can prepare his own controlled sourdough.

The lactic acid bacteria play a major role in the process of sourdough fermentation. They can quickly acidify the dough through production of organic acids such as acetic acid. They also produce other components such as ethanol, flavours, bacteriocins, exopolysaccharides and enzymes. The advantages of using sourdough fermentation are among others the following: (1 ) bread flavour improvement; (2) bread nutritional value improvement; (3) bread volume and texture improvement; (4) bread prolonged shelf-life. At the same time, the sourdough approach improves the processing of the dough itself, for example by reducing the stickiness and improving its viscoelastic properties. Lactic acid bacteria isolated from sourdoughs are mainly Lactobacillus, Leuconostoc, Pediococcus and/or Weissela, but the majority belongs to the Lactobacillus group. Lactic acid bacteria fermentation generates lactic acid and/or acetic acid that give the acidity to the sourdough. Saccharomyces cerevisiae is the most frequent yeast species in conventional sourdough. Other species of Saccharomyces, Candida, Pichia, Kluyveromyces and/or Hansenula have occasionally been isolated from sourdoughs.

The traditional sourdough production is time and cost consuming. The qualities of sourdough are also inconsistent. Modern industries use dominant strains to inoculate a starter dough, which can be used for sourdough productions by conditional controlled fermentation and followed by downstream processing e.g. drying or pasteurizing. These processes can produce powders, paste or liquid sourdoughs.

Most of the sourdoughs produced today are made according to European styles and preferences are not very in line with oriental taste preference. There is therefore a need for new sourdoughs that will improve the quality and the flavour of bakery and patisserie products such as bread, in particular (Asian-type) steamed breads.

SUMMARY OF THE INVENTION

The present invention relates to a Lactobacillus crustorum strain as deposited under the accession number LMG P-29154 at the BCCM/LMG culture collection, or variants thereof.

In a further aspect, the present invention relates to a baking composition for use in the preparation of bakery products comprising a Lactobacillus crustorum strain as defined herein. In a particular embodiment, the present invention relates to a baking composition as defined herein, wherein said baking composition is chosen form a starter culture for bakery products, a sourdough or a sourdough product.

In a particular embodiment, the present invention relates to a baking composition as defined herein, further comprising one or more strains of lactic acid bacteria and/or one or more strains of yeast. In particular said one or more strains of lactic acid bacteria are chosen from acid forming bacteria such as Leuconostoc or Lactobacillus, and/or wherein said one or more strains of yeast are chosen from Saccharomyces, Candida, Pichia, Kluyveromyces or Hansenula strains. More in particular, said one or more strains of lactic acid bacteria are chosen from Lactobacillus plantarum, Lactobacillus brevis, Lactobacillus sanfrancisciensis and/or Lactobacillus reuterii, and/or wherein said one or more strains of yeast are chosen from Saccharomyces cerevisiae and Saccharomyces exiguus.

In a particular embodiment, the present invention relates to a baking composition as defined herein, wherein said baking composition is a sourdough or a sourdough product, preferably fermented by at least a strain of Lactobacillus crustorum as defined herein.

In a particular embodiment, the present invention relates to a baking composition as defined herein, wherein said baking composition further comprises cereal or cereal fractions, and optionally sugar and/or minerals, preferably fermented by at least a strain of Lactobacillus crustorum as defined herein.

In a particular embodiment, the present invention relates to a baking composition as defined herein, wherein said baking composition is an active or inactive sourdough or sourdough product.

In a particular embodiment, the present invention relates to a baking composition as defined herein, wherein said baking composition is a starter culture.

In a further aspect, the present invention relates to a method for preparing a sourdough or a sourdough product as defined herein comprising the steps of:

fermenting a (liquid) mixture comprising cereal and/or cereal fractions, and a liquid, preferably water, with at least one strain of Lactobacillus crustorum LMG p-29154, thereby obtaining the (liquid) sourdough; and

- optionally drying said (liquid) sourdough thereby obtaining a dried composition.

In a further aspect, the present invention relates to the use of a baking composition as defined herein in the preparation of a food product. In a further aspect, the present invention relates to a bakery product comprising a baking composition as defined herein. In particular, said bakery product is a steamed bun.

FIGURE LEGENDS

Figure 1 shows the morphological differences on petri dish between the strain of Lactobacillus crustorum LMG P-29154 (figure 1A) and reference L. crustorum LMG 23699 (figure 1 B).

Figure 2 shows the result of comparison of aromas by SPME-GC-MS.

DETAILED DESCRIPTION

Before the present products, compositions, uses and methods of the invention are described, it is to be understood that this invention is not limited to particular products, compositions, uses and methods or combinations described, since such products, compositions, uses and methods and combinations may, of course, vary. It is also to be understood that the terminology used herein is not intended to be limiting, since the scope of the present invention will be limited only by the appended claims.

As used herein, the singular forms "a", "an", and "the" include both singular and plural referents unless the context clearly dictates otherwise.

The terms "comprising", "comprises" and "comprised of" as used herein are synonymous with "including", "includes" or "containing", "contains", and are inclusive or open-ended and do not exclude additional, non-recited members, elements or method steps. It will be appreciated that the terms "comprising", "comprises" and "comprised of" as used herein comprise the terms "consisting of, "consists" and "consists of".

The recitation of numerical ranges by endpoints includes all numbers and fractions subsumed within the respective ranges, as well as the recited endpoints.

The term "about" or "approximately" as used herein when referring to a measurable value such as a parameter, an amount, a temporal duration, and the like, is meant to encompass variations of +/-10% or less, preferably +/-5% or less, more preferably or less, and still more preferably +/-0.1 % or less of and from the specified value, insofar such variations are appropriate to perform in the disclosed invention. It is to be understood that the value to which the modifier "about" or "approximately" refers is itself also specifically, and preferably, disclosed. Whereas the terms "one or more" or "at least one", such as one or more or at least one member(s) of a group of members, is clear per se, by means of further exemplification, the term encompasses inter alia a reference to any one of said members, or to any two or more of said members, such as, e.g., any 5s3, ^4, 5s5, 5s6 or 5s7 etc. of said members, and up to all said members.

Unless otherwise defined, all terms used in disclosing the invention, including technical and scientific terms, have the meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. By means of further guidance, term definitions are included to better appreciate the teaching of the present invention.

In the following passages, different aspects of the invention are defined in more detail. Each aspect so defined may be combined with any other aspect or aspects unless clearly indicated to the contrary. In particular, any feature indicated as being preferred or advantageous may be combined with any other feature or features indicated as being preferred or advantageous.

Reference throughout this specification to "one embodiment" or "an embodiment" means that a particular feature, structure or characteristic described in connection with the embodiment is included in at least one embodiment of the present invention. Thus, appearances of the phrases "in one embodiment" or "in an embodiment" in various places throughout this specification are not necessarily all referring to the same embodiment, but may. Furthermore, the particular features, structures or characteristics may be combined in any suitable manner, as would be apparent to a person skilled in the art from this disclosure, in one or more embodiments. Furthermore, while some embodiments described herein include some but not other features included in other embodiments, combinations of features of different embodiments are meant to be within the scope of the invention, and form different embodiments, as would be understood by those in the art. For example, in the appended claims, any of the claimed embodiments can be used in any combination.

The present invention provides in a particular strain of lactic acid bacteria, wherein said strain is a strain of Lactobacillus crustorum that can be advantageously used to prepare starters, sourdoughs and baked products with improved properties. Preferably the strain of Lactobacillus crustorum is Lactobacillus crustorum LMG P-29154 as deposited on October 2, 2015 in the BCCM/LMG (Laboratorium voor Microbiologie - Bacterienverzameling; Universiteit Gent; K.L. Ledeganckstraat 35;B-9000 Gent, Belgium) under the accession numbers LMG P-29154 (see table A) or variants thereof. Table A. Indications relating to deposited microorganism LMG P-29154

Accordingly, the present invention relates to a Lactobacillus crustorum strain as deposited under the accession number LMG P-29154 at the BCCM/LMG culture collection, or variants thereof.

As referred to herein, the term "variants" refers to microbial variants such as mutational, insertional, and deletional variants of Lactobacillus crustorum LMG P-29154 as well as microbial variants having a whole genome sequence identity of at least 90%, more preferably at least 95% and for instance at least 96%, 97%, 98%, 99% or 99.9%.

In a further aspect, the present invention relates to a baking composition for use in the preparation of bakery products comprising a Lactobacillus crustorum strain as deposited under the accession number LMG P-29154 at the BCCM/LMG culture collection, or variants thereof.

According to a particular embodiment, the baking composition as defined herein, is chosen form a starter culture for bakery products, a sourdough or a sourdough product.

According to a particular embodiment, the baking composition as defined herein, further comprises one or more strains of lactic acid bacteria and/or one or more strains of yeast. More particular, said one or more strains of lactic acid bacteria are chosen from acid forming bacteria such as Leuconostoc or Lactobacillus, and/or wherein said one or more strains of yeast are chosen from Saccharomyces, Candida, Pichia, Kluyveromyces or Hansenula strains. More particular, said one or more strains of lactic acid bacteria are chosen from Lactobacillus plantarum, Lactobacillus brevis, Lactobacillus sanfrancisciensis and/or Lactobacillus reuterii, and/or wherein said one or more strains of yeast are chosen from Saccharomyces cerevisiae and Saccharomyces exiguus.

The particular strains as defined herein provide the bakery products prepared using the baking composition according to the present invention with particular aromatic profiles which provide particular characteristics to the bakery products.

According to a particular embodiment, the baking composition as defined herein composition is a sourdough or a sourdough product. It is a further object of the present invention to provide sourdoughs or sourdough products made with Lactobacillus crustorum LMG P- 29154. In the context of the present invention the term "sourdough" or "sourdough product" refers to a dough fermented by lactic acid bacteria and optionally yeast. A sourdough typically has a characteristic acidic flavour due to the production of lactic acid and/or acetic acid by the lactic acid bacteria, and some minor components, as well as the typical flavour top-notes produced by the yeast, if present. A sourdough or sourdough product may be further stabilized in one or another way (e.g. through drying, pasteurization, cooling, and/or freezing) so that it can be added to a regular dough or batter, thereby replacing the in-bakery produced pre-fermentation.

In a particular embodiment the sourdough or sourdough product as defined herein comprises cereal or cereal fractions, and optionally sugar and/or minerals. Preferably, the sourdoughs or sourdough products comprise cereal or cereal fractions, eventually mixed with sugar and/or minerals, wherein said sourdoughs are fermented by at least a strain of Lactobacillus crustorum LMG P-29154. More specifically, such sourdoughs provide a very good taste and very good physical properties to baked products such as bakery and patisserie products.

As used in the present application, the term "cereal", in the context of the present invention, refers to the edible components of plants of the botanical family of the Poaceae, including but not limited to species such as wheat, barley, oat, spelt, rye, sorghum, maize, triticale, millet, teff and/or rice. Preferably, the cereals are chosen among the group of wheat, maize (corn), rice or rye. More preferred cereals are rye, rice and wheat. An even more preferred cereal is wheat. The term "cereal fraction", in the context of the present invention, refers to all or part of the fractions resulting from mechanical reduction of the size of grains, through, as examples but not limited to, cutting, rolling, crushing, breakage or milling, with or without fractionation, through, as examples but not limited to, sieving, screening, sifting, blowing, aspirating, centrifugal sifting, wind sifting, electrostatic separation, or electric field separation. Preferred cereal fractions are flours, whole flours, brans and/or any combination thereof.

The term "sugar" as used herein refers to sucrose, glucose and compounds/products containing sucrose or glucose, such as molasses, sugar beet sugar, cane sugar and hydrolysed starches but not limited to these. As used herein, the amounts of sugar(s) refer to the sum of glucose and sucrose as measured by methods known in the art such as high- performance liquid chromatography (HPLC).

The term "minerals" refers to minerals used for the cultivation of lactic acid bacteria and comprises K + , Na + , Mg 2+ , Mn 2+ , Fe 2+ , P0 4 3" , S0 4 2" and CI " ions. More preferably it refers to K + and Mn 2+ .

According to a particular embodiment, the present invention provides sourdoughs or sourdough products, wherein said sourdoughs are fermented by additional microorganisms. In this embodiment, the strain of Lactobacillus crustorum, preferably Lactobacillus crustorum LMG P-29154 used to obtain the sourdoughs or sourdough products as taught herein are combined with conventional microorganisms, i.e. microorganisms that are used for preparing regular (traditional) sourdoughs. Such additional microorganisms may be preferentially chosen among lactic acid bacteria and/or yeasts. The lactic acid bacteria may be chosen among lactic acid forming bacteria such as Leuconostoc and Lactobacillus, preferably selected from the group consisting of Lactobacillus plantarum, Lactobacillus brevis, Lactobacillus sanfrancisciensis, and Lactobacillus reuterii. Yeasts are advantageously chosen among Saccharomyces, Candida, Pichia, Kluyveromyces or Hansenula, preferably Saccharomyces cerevisiae or Saccharomyces exiguus. In a preferred embodiment, the amount of yeasts comprised in the compositions as taught herein, in particular in the sourdoughs or sourdough products, is the amount needed for the leavening of dough such as bread dough.

In a particular embodiment the strain of Lactobacillus crustorum, preferably Lactobacillus crustorum LMG P-29154 is the only strain of lactic acid bacteria present in the sourdough.

In a particular embodiment the sourdough or sourdough product as defined herein is fermented by at least a strain of Lactobacillus crustorum, preferably Lactobacillus crustorum LMG P-29154. In a particular embodiment the sourdough or sourdough product as defined herein is in a liquid, a paste or a dry/powder form.

Sourdough products may come in many forms. A liquid sourdough product is probably the most commonly used type. However, also other types of sourdough products are available, including dried or dry sourdough products. Sourdough products under a dry form are typically obtained by drying a liquid sourdough product. Preferably, the dry matter of the solid/powdered composition is more than 85% (w/w), preferably more than 90%, and more preferably 92% or more. Said range thus also provides 86, 87, 88, 89, 91 , 93, 94, 95, 96, 97, 98, 99 or 100% dry matter.

According to a particular embodiment, the present invention provides in liquid sourdough products wherein said liquid sourdough product is characterized by having a dry matter between 10% (w/w) and 45%, preferably between 15% and 40%, more preferably between 20% and 35%. Said range thus also provides any of 16, 17, 18, 19, 21 , 22, 23, 24, 25, 26, 27, 28, 29, 30, 31 , 32, 33, 34, 35, 36, 37, 38, 39, 41 , 42, 43 or 44% dry matter.

In a particular embodiment the sourdough or sourdough product as defined herein is an active or inactive sourdough or sourdough product.

Preferably, the sourdough is an active sourdough. By the term "active sourdough" is meant that the sourdough contains active and/or viable microorganisms. An active sourdough can be used as a starter to produce pasty or other liquid compositions having the same specifications and properties as described above. Like conventional active sourdoughs, the active sourdoughs of the present invention guarantee homogeneity in quality and in processing. Advantageously the range of living cells in an active sourdough is between 10 7 and 10 11 , preferably between 10 7 and 10 10 , more preferably between 10 8 and 10 9 lactic acid bacteria cells/ml; and between 10 5 and 10 8 , preferably between 10 6 and 10 7 yeast cells/ml. In a particular embodiment the active sourdough is an active liquid sourdough.

In other preferred embodiments, the sourdough is inactive. By the term "inactive sourdough" is meant that the composition no longer contains active and/or viable microorganisms. In order to inactivate a sourdough as taught herein, the sourdough may be inactivated through (continuous) pasteurization, for example at a temperature of about 55 to about 90°C for about 10 sec to about 60 minutes. In a particular embodiment the inactive sourdough is an inactive liquid sourdough. In certain embodiments the pH of the sourdough is comprised between 4.0 and 5.0, preferably between 4.0 and 4.5.

In certain embodiments the sourdoughs of the present invention have a total titratable acidity (TTA) higher that 12, preferably between 12 and 300, more preferably between 12 and 100, even more preferably between 12 and 50, for example between 12 and 18. The Total Titratable Acidity is a product property commonly known to the person skilled in the art. The TTA refers to the amount (expressed in ml) of 0.1 N NaOH needed to bring the pH of 10 g of product to 8.4. The inventors have found that such TTA allows obtaining sourdoughs with improved properties, such as an improved flavour.

In certain embodiments the present invention relates to paste sourdough with a dry matter comprised between 30 and 70%, preferably between 40 and 60%.

In certain embodiments, the present invention relates to dried sourdoughs product obtained by drying liquid or paste sourdoughs product as taught herein. The drying of the liquid or of the paste sourdough can be performed using the typical drying techniques available to the skilled person. Preferably dried sourdoughs are obtained through fluidization, spray-drying or by drum-drying of the liquid or paste composition. Preferred dry matter of the solid/powdered composition is more than 90%, preferably 92%.

According to a particular embodiment, the baking composition as defined herein, is a starter culture for bakery products. In a particular embodiment, the baking composition as defined herein is a starter culture for a bakery product that comprises a strain of Lactobacillus crustorum LMG P-29154. In the context of the present invention a starter culture refers to living cells of Lactobacillus crustorum LMG P-29154 and optionally other microorganisms such as yeast that are used for example to produce a sourdough or a sourdough product. A starter culture may further comprise other strains of lactic acid bacteria and/or other strains of yeasts. Preferably lactic acid bacteria are chosen among acid forming bacteria such as Leuconostoc or Lactobacillus, preferably selected from the group of Lactobacillus plantarum, Lactobacillus brevis, Lactobacillus sanfrancisciensis and Lactobacillus reuterii. Yeast strains are advantageously chosen among Saccharomyces, Candida, Pichia, Kluyveromyces or Hansenula, preferably Saccharomyces cerevisiae and Saccharomyces exiguus. Starter cultures may be under dry or liquid form before being used. Dry starters may be rehydrated before use, for example by suspending the starter in water containing sugar and salt. In a particular embodiment the strain of Lactobacillus crustorum, preferably Lactobacillus crustorum LMG P-29154 is the only strain of lactic acid bacteria present in the starter. In a further aspect , the present invention provides in a method for preparing a sourdough or a sourdough product as defined herein, said method comprising the steps of:

fermenting a (liquid) mixture comprising cereal and/or cereal fractions, and a liquid, preferably water, with at least one strain of Lactobacillus crustorum LMG p-29154, thereby obtaining the (liquid) sourdough; and

optionally drying said (liquid) sourdough thereby obtaining a dried composition.

In particular embodiments the mixture may further comprise additional microorganisms. Such additional microorganisms may be preferentially chosen among lactic acid bacteria and/or yeasts. The lactic acid bacteria may be chosen among lactic acid forming bacteria such as Leuconostoc and Lactobacillus, preferably selected from the group consisting of Lactobacillus plantarum, Lactobacillus brevis, Lactobacillus sanfrancisciensis, and Lactobacillus reuterii. Yeasts are advantageously chosen among Saccharomyces, Candida, Pichia, Kluyveromyces or Hansenula, preferably Saccharomyces cerevisiae or Saccharomyces exiguus.

In a particular embodiment a strain of Lactobacillus crustorum, preferably Lactobacillus crustorum LMG P-29154 is the only strain of lactic acid bacteria present in the mixture.

In certain embodiments the method of the present invention provides a sourdough with a total titratable acidity (TTA) higher that 12, preferably between 12 and 300, more preferably between 12 and 100, even more preferably between 12 and 50, for example between 12 and 18. In certain embodiments such TTA is obtained after 24 hours of fermentation.

The present method allows the preparation of an industrially very useful composition which improves the taste of baked products (obtained with the sourdoughs), and which at the same time provides baked products with satisfying physical properties such as satisfying volume. In preferred embodiments the mixture of wheat flour and water is in a ratio of about 1 to 2.5 and is fermented at about 30 to 40°C, preferably 35 to 38°C for about 12 to 48 hours, preferably for about 12 to 24h.

In a further aspect, the present invention relates to the use of a baking composition according to the present invention in the preparation of a food product, preferably a baked product, more preferably a bakery or patisserie product. More particularly, the present invention provides in the use of a baking composition according to the present invention as part of an improver, a premix or a complete mix in the preparation of baked products.

An "improver" as used herein refers to a composition of the invention further comprising ingredients and/or technological aids used for their beneficial properties during the preparation of baked products and/or after baking. These properties comprise but are not limited to aspect, volume, freshness, conservation, colour, structure or short bite of the baked products.

The term "premix" as used herein refers typically to an improver composition wherein the concentration in "active" component is lower than in a bakery improver. Typically a premix is used at a higher dose than an improver (weight/weight of flour).

The term "complete mix" as used herein refers typically to a composition comprising all the ingredients needed to prepare a dough that can be baked to obtain a baked product, generally with the exception of water. In particular when the leavening agent is a biological agent, more particularly baking yeast, it can also be excluded from the complete mix. A complete mix according to the present invention comprises the sourdough composition according to the invention and all the ingredients needed to prepare a dough that can be baked to obtain a baked product.

More particularly, the present invention provides in the use of a sourdough product according to the present invention for stabilizing a liquid baker's yeast suspension.

In a further aspect, the present invention relates to a bakery product comprising a baking composition according to the present invention.

It is still an object of the present invention to provide bakery products containing or obtained with sourdough made with one or more strains of Lactobacillus crustorum, preferably Lactobacillus crustorum LMG P-29154. In certain embodiments, the baked product may be an unleavened, a yeast-leavened, or a chemically leavened baked product, the major ingredient of which is flour derived from cereal grains. The baked product may also contain fat or fat replacer, sugar, eggs, gluten, starch, hydrocolloids, enzymes, emulsifiers, oxidizing or reducing compounds, prebiotic compounds and/or an improver. Examples of baked products are bakery products and patisserie products. Examples of bakery products are breads, steamed breads, baguettes, rolls, soft rolls, donuts, buns, microwavable buns, Danish pastry, hamburger rolls, pizza and pita bread. Examples of patisserie products are cakes, loaf cream and pound cakes, cup cream and pound cakes, sponge cakes, muffins, cake donuts, brownies, and waffles. Preferably, the sourdoughs of the present invention are used to prepare steam buns.

The invention will be described in the following non-limiting examples.

EXAMPLES

Example 1 : Isolation and characterization of a new strain of Lactobacillus crustorum

Lactobacillus crustorum LMG P-29154 was isolated from a source in China. The strain of Lactobacillus crustorum LMG P-29154 (figure 1A) shows morphological differences with reference L. crustorum LMG 23699 (figure 1 B) on petri dish (see figure 1 A and 1 B).

Example 2: liquid sourdough

Strains : Lactobacillus crustorum LMG P-29154 (deposited on November 12, 2015 at the BCCM/LMG (Laboratorium voor Microbiologie - Bacterienverzameling; Universiteit Gent; K.L. Ledeganckstraat 35;B-9000 Gent, Belgium), Lactobacillus crustorum LMG 23699 obtained from the BCCM/LMG bacterial collection.

Pure strains were grown in MRS medium (10 g/l peptone, 8 g/l meat extract, 4 g/l yeast extract, 20 g/l glucose, 1 g/l Tween 80, 2 g/l K 2 HP0 4 , 5 g/l Na-acetate.3H 2 0, 2 g/l triammonium citrate, 0.2 g/l MgS0 4 .7H 2 0, 0.05 g/l MnS0 4 .4H 2 0, pH 6.5) and used to inoculate a mixture of 175 g wheat flour (Pur8, Ceres, Belgium) and 325 g water. The mixture was incubated for 48h at 37°C in shake flasks rotating at 100 rpm.

pH and total titratable acidity (TTA) of the sourdoughs were measured during fermentation. The TTA refers to the amount (expressed in ml) of 0.1 N NaOH needed to bring the pH of 10 g of the product to 8.4.

Table 1 :

Example 3: Dried sourdough

The Lactobacillus crustorum LMG P-29154 strain was grown for 2-3 days at 35°C in 50 ml in MRS medium ((10 g/l peptone, 8 g/l meat extract, 4 g/l yeast extract, 20 g/l glucose, 1 g/l Tween 80, 2 g/l K 2 HP0 4 , 5 g/l Na-acetate.3H20, 2 g/l triammonium citrate, 0.2 g/l MgS0 4 .7H 2 0, 0.05 g/l Μη50 4 .4Η 2 0, pH 6.5). 150 μΙ of culture from preceding step were inoculated in 1 .5 L of fresh MRS medium and incubated at 35°C for 2-3 days.

The cultures were then centrifuged (10 min at 4000 rpm) and rinsed before inoculation of a fermentolevain. A blend of 10.5 kg wheat flour with 19.5 kg water was made in the fermentolevain (FL80 - Bertrand-Puma, France). The blend was inoculated with the rinsed biomass of 2 flasks of 1.5 I. Fermentation was performed for 24 h at 35°C.

After the first fermentation, the mixture was further inoculated with an amount of yeast (baker's yeast strain of Saccharomyces cerevisiae) corresponding to about 10 7 cfu/g (colony forming units / g) and incubated at 30°C and 100 rpm for 24 hours.

After fermentation, the pH of the sourdough was adjusted with sodium carbonate (Na 2 C0 3 ) till a pH of about 4 to 4.2. The sourdough were transferred to a mixing tank which feeds a Niro P6.3 spraytower. Airflow inlet temperature was set to 185°C and airflow was around 630 kg/h. Airflow outlet temperature varied from 120°C at the beginning up to 90-100°C at the end. Product (inlet flow about 151/h) was sprayed into the tower by a centrifugal pump turning at 1 .5Hz. The dried product was collected in the cyclone situated after the bottom of the spray chamber.

Example 4: Comparison of aromas by SPME-GC-MS

The content in volatile molecules of the sourdoughs in example 2 has been compared by SPME-GC-MS (solid phase microextraction (SPME) and gas chromatography-mass spectrometry (GC-MS).

HS-SPME-GC-MS configuration consisted of a gas chromatograph-mass spectrometer HP 7890A 5975C (Agilent Technologies®) equipped with an MPS-2W autosampler (Gerstel®). ChemSensor® software (G1701 BA, Version B.01.00, Agilent Technologies®) and The Unscrambler® multivariate analysis software (9.8, Camo®, Oslo, Norway) were loaded into the GC-MS system.

A sample weight of 1 g of each sourdough was weighed in a 20ml glass vial, which was closed with a magnetic cap with a silicone/PTFE septum. The samples were preheated for 10 min at 40°C and the volatile molecules were extracted by SPME (Fibre type DVB/CAR/PDMS Supelco Gray ® 57329-U) for 30 min at equal temperature. After HS- SPME isolation, the splitless thermal desorption of the sourdoughs from the fibre was performed for 5 min at 250°C in the GC injector (SPME liner of 0.75 mm i.d.). The GC column (RESTEK Stabilwax columns (fused silica)) was maintained at 40°C for 7min, and then programmed at a rate of 16°C/min to a temperature of 230°C, which was held for 8 min. Helium was used as carrier gas (1 ml/min). Injector and detector (MS-source) were kept at 240°C and 230°C, respectively. The mass spectra were measured by electron impact of 70 eV. The TIC (total ion current) chromatograms were recorded by monitoring in a mass-to- charge ratio (m/z) range of 40-180 amu. The identification of volatiles was made by comparing the mass spectra of the different components to those in a Mass Spectral Library Wiley275® (J. Wiley & Sons LTD®).

The result of the analysis is depicted on figure 2. It shows that the aromatic profiles of the sourdoughs are different. Among other molecules, the sourdough obtained with Lactobacillus crustorum P-29154 shows a higher level of acetic acid, isovaleric acid and benzylalcohol.

Example 5: Steamed buns

Steamed buns were prepared using sourdoughs of example 1. Before being added to the recipe, the sourdoughs of example 1 were neutralized with sodium carbonate (Na 2 C0 3 ) to a pH of about 4.0-4.2. The compositions of the buns dough are shown in table 2.

Table 2

* contains emulsifiers, ascorbic acid and enzymes The ingredients were mixed in a Diosna mixer at low speed (1 10 rpm) for 5 minutes and at high speed (220rpm) for 1 minute. The dough was then fermented for 120 minutes at 37°C with a humidity of 85%. The dough was then mixed with 25 % fresh flour and 3 % water, at low speed for 3 minutes and high speed for 1 minute. The dough was then pressed with a sheeter to a thickness of 5 to 7 mm. The sheet was rolled and cut it into 50 g pieces. Each piece was then manually rounded. The dough pieces were then placed on a tray and fermented for 25 minutes at 37°C, 85 % humidity. Thereafter, the doughs were placed in a steamer and steamed for 15 minutes at 100°C.

Triangle test

The two types of steam buns were presented to a panel of 19 people in a triangle test. In this test three samples are proposed. Two of them are identical, the third one is different. People are asked to find the sample that is different from the 2 other. A response is mandatory.

The number of correct answers is counted. Then the statistics (p-value) are calculated and compared to the level of risk taken for the test. A p-value lower than the risk shows a significant difference.

1 1 judges out of 19 found the correct answer.

The p-value (2,41 %) was inferior to the alpha risk level of the test (10%) showing that there was a significant perceptible sensory difference between the steam buns made with sourdough obtained with L. crustorum LMG P-29154 and buns obtained with a sourdough obtained with L. crustorum LMG 23699.

Example 6: Northern China-type steamed breads

Northern China-type steamed breads were prepared using the sourdough of example 3. A reference steamed bread without sourdough was prepared using the same recipe. Ingredients are listed in the table 3.

Table 3

Breads

Ingredient (baker's %) Ref5 Crust5 Wheat flour 100 100

Water 50 51

Dried sourdough with L. crustorum LMG P-29154 3-5

Instant Active Dry yeast 0.8 0.8

All ingredients were mixed in a Diosna mixer at low speed (1 10 rpm) for 5 minutes. The dough was then pressed to a thickness of about 5 to 7 mm. This pressing was repeated 5 times. The dough sheet was then rolled up and cut into small piece of 50 g. Then the small pieces of dough were rounded and placed on a tray. The doughs were then proofed for 35 minutes at 35 - 37°C, 85% humidity. After proofing, the doughs were steamed at 100°C for 12 minutes. The steamed breads were cooled down to room temperature and optionally stored frozen for one week.

Consumer preference test

The steamed breads were evaluated by a panel of consumers. The participants were asked to give their preference for one sample compared to the other in terms of overall qualities and flavour qualities. 97 participants attended the evaluation. The results were analysed using XLSTAT with Wilcoxon Model. The results are shown in Table 4.

Table 4

The results show that there was a significant difference of the participant's preferences for one of the bread type (p<a), both in terms of overall qualities and flavour qualities. The steamed bread made with the sourdough obtained with Lactobacillus crustorum LMG P29154) was preferred by the participants Example 7: Southern China-type steamed breads

Southern China-type steamed breads were prepared using the sourdough of example 2. A reference steamed bread without sourdough was prepared using the same recipe. Ingredients are listed in the table 5.

Table 5

All ingredients were mixed at low speed (1 10 rpm) for 5 minutes. The dough was then pressed to a thickness of about 5 to 7 mm. This pressing was repeated 10 times. The dough sheet was then rolled up and cut into small dough pieces of 20 g with a pillow shape. The dough pieces were then proofed for 35 minutes at 35 - 37°C, 85% humidity. After proofing, the dough was steamed at 100°C for 12 minutes. The steamed breads were cooled down to room temperature and optionally stored frozen for one week.

Consumer preference test

The steamed breads were evaluated by a panel of consumers. The participants were asked to give their preference for one sample compared to the other in terms of overall qualities and flavour qualities. 1 18 participants attended the evaluation. The results were analysed using XLSTAT with Wilcoxon Model. The results are shown in Table 6. Table 6

The results show that there was a significant difference of the participant's preferences for one of the bread type (p<a), both in terms of overall qualities and flavour qualities. The steamed bread made with the sourdough obtained with Lactobacillus crustorum LMG P29154) was preferred by the participants.