Method for the enzymatic production of soluble fibres

Abstract

The invention relates to a method for preparing a mixture of poorly-digestible alpha-glucans from a substrate rich in oligosaccharides having a degree of polymerisation (DP) of 4.

Description

Title: Process for obtaining soluble fibers by enzymatic means Technical field

[0001] The present invention relates to a process for preparing a mixture of poorly digestible a-glucans from a substrate rich in oligosaccharides having a degree of polymerization (DP) of 4. In the present application, this substrate designates a syrup containing oligosaccharides with a content of oligosaccharides having a degree of polymerization (DP) of 4 of at least 40%, preferably at least 45%, even more preferably at least 50%.

[0002] The invention also relates to a mixture of poorly digestible α-glucans.

[0003] The present invention also relates to the use of an α-glucanotransferase capable of creating α(1-6) glucosidic bonds to reduce the digestibility of a mixture of α-glucans. State of the prior art

[0004] Dietary fiber plays an important role in the human diet. Dietary fibers are divided into soluble fibers, which are soluble in water and have a gelling capacity, and insoluble fibers. Soluble fibers, including branched maltodextrins, are particularly interesting because they are poorly digestible. Therefore, their incorporation into the diet helps reduce the glycemic index of a food and prolong the feeling of satiety. They also have prebiotic properties on the intestinal flora, meaning they are able to selectively promote the growth of certain probiotic bacteria or the activity of the microbiota, providing health benefits.

[0005] Until now, soluble fibers, including branched maltodextrins, were mainly obtained by physicochemical means.

[0006] This is particularly the case for maltodextrin marketed by the Applicant company under the brand name NUTRIOSE® FM10 as a water-soluble fiber.

[0007] There are other soluble fibers obtained by physicochemical means, such as PROMITOR® marketed by the company Tate and Lyle, FIBERSOL® or LITESSE® marketed by the company Dupont Nutrition and Biosciences.

[0008] Numerous studies have demonstrated that digestibility properties are directly related to the percentages of different types of sugar bonds within soluble fibers.

[0009] Indeed, standard maltodextrins are rapidly digestible and are defined as purified and concentrated mixtures of glucose and glucose polymers essentially linked in alpha 1 4 (hereinafter 1 — > 4 or a(1 -4)) with only 4 to 5% of alpha 1 6 glucosidic bonds (hereinafter 1 - 6 or a(1- 6)), of extremely varied molecular weights, completely soluble in water and with low reducing power.

[0010] By increasing the percentage of alpha 1 — > 6 or alpha 1 — > 3 bonds, the degree of branching of maltodextrins is increased, which makes them more resistant to digestion.

[0011] The enzymatic approach, which uses enzymes capable of promoting the creation of "branched" type bonds, has many advantages in terms of safety, environmental protection, and also offers better specificity.

[0012] Originally, most enzymatic processes for producing soluble fiber were carried out using sucrose as the enzyme substrate to create new bonds. For example, application WO2015183714 describes an enzymatic reaction from a mixture of sucrose and an α-glucan substrate.

[0013] Today, most enzymatic processes use amylomaltases to produce soluble fiber from starch.

[0014] It is desirable to obtain soluble fibers enzymatically from substrate, in the absence of sucrose. Detailed description of the invention

[0015] The Applicant company then found that it was possible, from a syrup rich in oligosaccharides having a degree of polymerization (DP) of 4, to obtain fibers of interest in human and animal nutrition, by enzymatic means. The Applicant company thus developed a process which uses a particular enzyme, capable of creating α(1-6) bonds from syrup rich in DP4 oligosaccharides.

[0016] In a first aspect, the present invention relates to a process for preparing a mixture of α-glucans, preferably a mixture of branched maltodextrins, comprising a step of bringing together a substrate and an enzyme, said substrate being a syrup rich in oligosaccharides having a degree of polymerization (DP) of 4 and said enzyme being an α-glucanotransferase capable of cleaving α(1-4) glucosidic bonds and creating α(1-6) glucosidic bonds.

[0017] According to the present invention, the terms "a-glucan", "soluble fiber", "soluble dietary fiber" are used interchangeably. They define oligosaccharides composed of at least 3 glucose units linked together by a-glycosidic (or a-glucosidic) bonds.

[0018] The classification of a-glucans is based primarily on the measurement of their reducing power, classically expressed by the notion of "dextrose equivalent" ("Dextrose Equivalent" or DE). On this particular point, the definition of maltodextrins included in the Monograph Specifications of the Food Chemical Codex specifies that the DE value for a maltodextrin must not exceed 20. Above 20, these are glucose syrups.

[0019] However, such a measurement of DE is insufficient to accurately represent the molecular distribution of α-glucans. Indeed, the completely random acid hydrolysis of starch, or its somewhat more ordered enzymatic hydrolysis, provide mixtures of glucose and glucose polymers that cannot be precisely defined by DE measurement alone, and which include short molecules with low DP, as well as very long molecules with high DP.

[0020] The DE measurement actually only gives an approximate idea of ​​the average DP of the mixture of glucose and glucose polymers constituting the α-glucans and therefore of their number-average molecular mass (Mn). To complete the characterization of the molecular mass distribution of α-glucans, the determination of another parameter is important, that of the weight-average molecular mass (Mp).

[0021] In practice, (Mn) and (Mp) are determined experimentally by different analytical techniques, such as a measurement method suitable for glucose polymers, which is based on gel permeation chromatography on chromatography columns calibrated with pullulans of known molecular masses.

[0022] The Mp / Mn ratio is called the polymolecularity index (PI) and allows the overall characterization of the molecular mass distribution of a polymer mixture. As a general rule, the molecular mass distribution of standard maltodextrins leads to PIs between 5 and 10.

[0023] These different parameters also reflect the α-glycosidic bond profile of α-glucans. Indeed, a standard α-glucan mixture has a very high percentage of "linear" α(1-4) bonds (greater than 90%) and a low percentage of so-called "branched" bonds (α(1-2), α(1-3) and α(1-6)).

[0024] The method according to the present invention makes it possible to reduce the percentage of a(1-4) bonds in favor of a(1-6) bonds, which has the advantage of reducing the digestibility of the mixture of a-glucans obtained by the method.

[0025] The mixture of α-glucans prepared according to the process of the invention is preferably a mixture of branched maltodextrins.

[0026] For the purposes of the invention, branched maltodextrins are understood to mean maltodextrins whose content of α(1-6) glucosidic bonds is higher than that of standard maltodextrins.

[0027] Standard maltodextrins are defined as purified and concentrated mixtures of glucose and glucose polymers primarily linked in a(1-4) with only 4-5% a(1-6) glucosidic linkages, with molecular weights extremely varied, completely soluble in water and with low reducing power.

[0028] According to one embodiment of the invention, the syrup rich in oligosaccharides having a DP of 4 comprises at least 40%, preferably at least 45%, even more preferably at least 50% of oligosaccharides having a DP of 4.

[0029] According to one embodiment of the invention, the syrup rich in oligosaccharides having a DP of 4 has a dextrose equivalent (DE) greater than 20.

[0030] According to a preferred embodiment of the invention, the syrup rich in DP4 is a syrup having the characteristics described in Table 1 below.

[0031] In a preferred embodiment of the invention, the substrate is present at a concentration of between 50 g / L and 500 g / L, preferably between 100 g / L and 200 g / L in the reaction medium.

[0032] In a preferred embodiment of the invention, the α-glucanotransferase capable of cleaving α(1-4) glucosidic bonds and creating α(1-6) glucosidic bonds is the protein having the sequence SEQ ID No: 1 or a protein having at least 90% identity with the protein having the sequence SEQ ID No: 1 (hereinafter referred to as GT#19). Preferably, it is a protein having at least 91%, even more preferably, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, at least 99.5%, at least 99.6%, at least 99.7%, at least 99.8%, at least 99.9% identity with the protein having the sequence SEQ ID No: 1. The sequence SEQ ID No: 1 corresponds to the Genbank accession number WP_053069107.1.

[0033] As shown in the examples, the inventors have shown that the GT#19 enzyme is capable of modifying a syrup rich in DP4 so as to make it poorly digestible, with a % hydrolysis according to the AQAC2002.02 method less than or equal to 45%).

[0034] According to one embodiment of the invention, the enzyme is added at a concentration of between 0.01 and 1 mg / mL of reaction medium, preferably between 0.05 and 0.5 mg / mL, even more preferably approximately 0.1 mg / mL of reaction medium.

[0035] According to one embodiment of the invention, the substrate and the enzyme are brought together for a period of between 12 and 48 hours, preferably approximately 24 hours.

[0036] According to one embodiment of the invention, the substrate and the enzyme are brought together at a temperature of between 20 and 40°C, preferably approximately 37°C.

[0037] According to one embodiment of the invention, the substrate and the enzyme are brought together at a pH of between 5 and 6.5, preferably between 5.5 and 6, even more preferably approximately 5.75.

[0038] In one embodiment of the invention, the method further comprises a step of enzymatic treatment with an α-glucanotransferase capable of cleaving the α(1-4) glucosidic bonds and creating α(1-3) glucosidic bonds. It may be, for example, a protein having the sequence SEQ ID No: 2 or a protein having at least 90% identity with the protein having the sequence SEQ ID No: 2 (hereinafter referred to as GT#11). Preferably, it is a protein having at least 91%, even more preferably, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, at least 99.5%, at least 99.6%, at least 99.7%, at least 99.8%, at least 99.9% identity with the protein having the sequence SEQ ID No: 2. The sequence SEQ ID No: 2 corresponds to the Genbank accession number AOR73699.1.

[0039] According to one aspect, the present invention also relates to a mixture of a-glucans, preferably a mixture of branched maltodextrins, obtainable by the method described above.

[0040] This mixture of a-glucans is characterized by its low digestibility according to the AOAC 2002.02 method. Advantageously, the method according to the invention makes it possible to reduce by a factor of at least 2, preferably at least 2.5, even more preferably at least 3, the hydrolyzable fraction, measured according to the AOAC 2002.02 method, compared to the starting substrate.

[0041] The AOAC 2002.02 method can in particular be implemented using the “HPAEC-PAD assay” part of the “resistant Starch, K-RSTAR 06 / 18” kit marketed by the company Megazyme® as described in Example 1, part 5 below.

[0042] The method according to the present invention makes it possible to increase the percentage of α(1-6) bonds by a factor of at least 3, preferably at least 3.5, even more preferably at least 4, compared to the starting substrate.

[0043] The percentage of α(1-6) linkages can be measured by the Hakomori method (1964 HAKOMORI A Rapid Permethylation of Glycolipid, and Polysaccharide Catalyzed by Methylsulfinyl Carbanion in Dimethyl Sulfoxide) as described in Example 1, Part 8 below or by proton NMR as described in Example 1, Part 7 below.

[0044] According to one aspect, the present invention relates to a mixture of α-glucans, preferably a mixture of branched maltodextrins, characterized in that it has: - a rate of hydrolyzable fibers, less than 55%, preferably less than 50%, even more preferably less than 45%, - and / or at least 20% a(1-6) bonds, wherein the fiber content corresponds to the hydrolyzable (i.e., non-resistant) fraction according to the AOAC 2002.02 method and the percentage of a(1-6) bonds represents the molar percentage of a(1-6) bonds relative to the total number of glycosidic bonds, measured by the Hakomori method.

[0045] Preferably, the rate of hydrolyzable fibers is less than 44%, preferably less than 43%, even more preferably less than 42%, 41%, 40%, 39%, 38%, 37%, 36%, 35%, 34%, 33%, 32%, 31%, 30%.

[0046] Preferably, the level of hydrolyzable fibers is greater than 5%, preferably greater than 10%, 11%, 12%, 13%, 14%, 15%, 18%, 19%, 20%, 21%, 22%, 23%, 24%, 25%.

[0047] Preferably, the level of hydrolyzable fibers is between 5% and 45%, preferably between 10% and 45%, preferably between 20% and 44%, more preferably between 30% and 45%.

[0048] Preferably, the percentage of α(1-6) bonds is at least 21%, preferably at least 22%, even more preferably at least 23%, at least 24%, at least 25%, at least 26%, at least 27%, at least 28%, at least 29%, at least 30%, at least 31%, at least 32%, at least 33%, at least 34%, at least 35%.

[0049] Preferably, the percentage of a(1-6) bonds is at most 40%, preferably at most 36%, at most 35%, at most 34%, at most 33%, at most 32%, at most 31%.

[0050] Preferably, the percentage of α(1-6) bonds is between 20% and 40%, preferably between 20% and 35%, preferably between 25% and 35%.

[0051] Preferably, the percentage of α(1-3) bonds is at least 2%, preferably at least 3%.

[0052] Preferably, the percentage of a(1-3) bonds is at most 6%, preferably at most 5%.

[0053] Preferably, the percentage of α(1-3) bonds is between 2% and 8%, preferably between 3% and 5%.

[0054] Preferably, the percentage of α(1-2) bonds is at least 1%, preferably at least 2%.

[0055] Preferably, the percentage of a(1-2) bonds is at most 8%, preferably at most 6%, at most 5%, at most 4% or at most 3%.

[0056] Preferably, the percentage of a(1-4) bonds is at most 80%, preferably at most 70%, at most 65%.

[0057] Preferably, the percentage of α(1-4) bonds is at least 50%, preferably at least 55%, at least 60%.

[0058] Preferably, the percentage of α(1-4) bonds is between 50% and 80%, preferably between 55% and 70%, preferably between 55% and 65%.

[0059] Preferably, the mixture of α-glucans, which is preferably a mixture of branched maltodextrins, is characterized in that it has: - a rate of hydrolyzable fibers, less than 55%, preferably less than 50%, even more preferably less than 45%, - and has one or more of the following characteristics: - between 20% and 40% of a(1-6) bonds, - between 20% and 40% of a(1-3) bonds, - between 2% and 8% of a(1-2) bonds, - between 50% and 80% of a(1-4) bonds, in which the fiber content corresponds to the hydrolyzable (i.e. non-resistant) fraction according to the AOAC 2002.02 method and the percentage of a(1-6), a(1-3), a(1-2), or a(1-4) bonds represents the molar percentage of said type of bonds relative to the total number of glycosidic bonds, measured by the Hakomori method.

[0060] Preferably, said bond levels a(1-6), a(1-3), a(1-2), or a(1-4) are such that the sum of their molar percentage is equal to 100%.

[0061] The present invention also relates to the use of a mixture of a-glucans obtained according to the process described above and of a mixture of a-glucans having the properties described above for the preparation of food for human or animal consumption.

[0062] Typically, the α-glucan blend of the invention can be used to promote gut health, blood sugar management, satiety and weight management, and sustained energy release.

[0063] Finally, in another aspect, the present invention relates to the use of a glucanotransferase capable of cleaving α(1-4) glucosidic bonds and creating α(1-6) glucosidic bonds to decrease the digestibility of a mixture of α-glucans, said glucanotransferase having the sequence SEQ ID No: 1 or a protein having at least 90% identity with the protein having the sequence SEQ ID No: 1.

[0064] In this aspect of the invention, the mixture of α-glucans is preferably an oligosaccharide-rich syrup, in particular an oligosaccharide-rich syrup having a DP of 4 as described in the first aspect of the invention.

[0065] Preferably, the decrease in digestibility is a decrease by a factor of at least 2, preferably at least 2.5, even more preferably at least 3 of the hydrolyzable fraction, measured according to the AOAC 2002.02 method, compared to the starting substrate.

[0066] The invention will be better understood with the aid of the following examples, which are intended to be illustrative and not limiting.

[0067] Example 1: Preparation of branched maltodextrins from syrup rich in DP4: materials and methods

[0068] 1. Preparation of a DP4 substrate solution

[0069] The starting substrate used was a syrup rich in DP4, presenting the characteristics described in Table 1:

[0070] [Table 1]

[0071] Different substrate solutions (DP4-rich syrup) in 50mM sodium acetate buffer, pH 5.75 were prepared, at concentrations of 100g / L, 200g / L or 400g / L.

[0072] 2. Production of recombinant enzymes.

[0073] The following enzymes have been produced recombinantly: - Enzyme GT#11: a-4,3 glucanotransferase from Lactobacillus fermentum NC2970 having the amino acid sequence listed in Genbank under the reference AOR73699.1 (SEQ ID No. 2) - Enzyme GT#19: glycosyl hydrolase GH70 from Lactobacillus mucosae having the amino acid sequence listed in Genbank under the reference WP_053069107.1. (SEQ ID No. 1)

[0074] E. coli BL21 star cells containing plasmid pET-21 a-enzyme No. X (to produce different enzymes, including GT#11 and GT#19) were cultured in ZYM-5052 medium containing 1% glycerol and 1% lactose. At the end of culture, cells were centrifuged at 6,500g for 10 min, cell pellets resuspended at a DQ600 nm of 80 in 20 mM phosphate buffer pH=7.4 containing 300 mM NaCl and 20 mM imidazole, and cells lysed by cold sonication using 4 cycles of 20 seconds at 30% amplitude followed by 4 minutes of rest. Cell debris was separated from solubilized proteins by centrifugation for 30 minutes at 10,000g.

[0075] 3. Purification of enzymes

[0076] Purification of the proteins of interest was carried out on Cobalt resin (Invitrogen) loaded with divalent cobalt ions (CO 2+), for which the polyhistidine tag has an affinity. Elution was achieved by creating a competition between the polyhistidine tag and increasing concentrations of imidazole. Briefly, 10 to 35 mL of E. coli cell extract were placed in contact for 1 hour with 1 mL of Cobalt resin previously equilibrated with 25 mL of 20 mM Phosphate buffer pH=7.4 containing 300 mM NaCl and 20 mM imidazole. Filtration of the resin on a frit allows the removal of all unbound proteins. The resin was then washed 5 times with 40 mL of 20 mM Phosphate buffer pH=7.4 containing 300 mM NaCl and 20 mM imidazole. Finally, elution was carried out with 3 mL of 20 mM Phosphate buffer pH=7.4 containing 300 mM NaCl and 250 mM imidazole for 5 minutes in order to remove the enzymes of interest.The enzyme solutions were then dialyzed (membrane cutoff threshold 10 kDa) against 5 L of 50 mM sodium acetate buffer, pH=5.75 (overnight, 4°C with stirring) in order to remove NaCl and imidazole. The dosage of the different protein solutions was carried out by measuring their absorbance at 280 nm using a nanodrop 2000 spectrophotometer (Thermofisher). The molecular extinction coefficients s were determined using the ProtParam tool application of the ExPASy bioinformatics resource portal.

[0077] 4. Enzymatic reactions

[0078] Reactions were performed with 0.1 mg / mL of purified and dialyzed enzyme in the presence of 10%, 20% or 40% substrate in 50 mM sodium acetate buffer, pH=5.75. Reactions were incubated with shaking for 24 h at 37°C. Reactions were stopped by heating (95°C for 5 minutes). Samples at initial and final times were taken to analyze the specificity of the enzymes using different analytical techniques (HPAEC-PAD, NMR).

[0079] 5. Digestibility test

[0080] The transfer reactions were lyophilized after freezing at -80°C for 24 hours. 25 mg of lyophilized products were taken up in 1 mL of 100 mM sodium maleate buffer containing 30 U of pancreatic α-amylase. and 3 U of amyloglucosidase (resistant Starch kit, Megazyme K-STAR 06 / 18, which implements the AOAC 2002.02 method). The reactions were incubated for 16 hours at 37°C. The products were diluted in water before HPAEC PAD analysis.

[0081] 6. Chromatoqraphical analyzes

[0082] The obtained products were analyzed by anion exchange chromatography coupled to a pulsed amperometric detector (HPAEC PAD - High Performance Anion Exchange Chromatography with Pulsed Amperometric Detection). The analyses were carried out on a Thermo ICS6000 system equipped with a CarboPac™ PA100 analytical column (2 mm x 250 mm) coupled with a CarboPac™ PA100 guard pre-column (2 mm x 50 mm). A gradient of sodium acetate in 150 mM sodium hydroxide was applied at a flow rate of 0.250 ml.min-1 according to the following profile: 0-5 min, 0 mM; 5-35 min, 0-300 mM; 35-40 min, 300-450 mM; 40-42 min, 450 mM. Detection was performed using a gold working electrode and an Ag / AgCl pH reference cell. Samples were diluted to a total dry mass of 1 gL-1 before injection.

[0083] 7. NMR.

[0084] The Specters 1 H, 13C and HSQC were recorded on a Bruker Avance 500MHz equipment at 298K with a BBI 5 mm z-gradient H-BB-D probe. Data were acquired and processed using TopSpin 3 software.

[0085] 8. Hakomori Method

[0086] The Hakomori method (1964 HAKOMORI A Rapid Permethylation of Glycolipid, and Polysaccharide Catalyzed by Methylsulfinyl Carbanion in Dimethyl Sulfoxide) allows the chemical characterization of osidic bonds by differentiating between free OH groups and bound groups. It is a destructive method comprising the steps of methylation, hydrolysis, reduction with NaBD4, acetylation and analysis by mass spectrometry

[0087] Example 2: preparation of branched maltodextrins from syrup rich in DP4: results

[0088] The results of the different enzymatic reactions are presented in Table 2 below, which shows the percentages of a-1,6; a-1,3 and a-1,4 measured by proton NMR or by the Hakomori method and % hydrolysis (AOAC 2002.02) in the reaction products obtained.

[0089] [Table 2]

[0090] MP: Raw Material, = DP4 Syrup

[0091] The inventors have demonstrated that the GT#19 enzyme is capable of modifying the syrup rich in DP4 so as to make it poorly digestible (% hydrolysis according to the AOAC2002.02 method less than or equal to 45%).

[0092] The product obtained by this enzymatic treatment with the enzyme GT#19 contains significantly fewer α-1,4 bonds and more α-1,6 bonds than the starting point. The number of α-1,2 and α-1,3 bonds is not modified. The enzyme GT#19 is therefore an α-4,6 glucanotransferase.

[0093] Conversely, treatment with another GT, the GT#11 enzyme, leads to a decrease in the percentage of a-1,4 bonds and to the appearance of a-1,3 bonds. The digestibility of the product obtained by treatment with the GT#11 enzyme is also reduced (53 and 55%, for respective initial concentrations of 100 and 200 mg / mL, compared to 84 and 88% for untreated substrates).

[0094] Advantageously, the mixture of a-glucans according to the present invention also has an interesting in vitro digestibility profile according to the Englyst method.

Claims

Claims

1. A process for preparing a mixture of α-glucans comprising a step of bringing together a substrate and an enzyme, said substrate being a syrup rich in oligosaccharides having a degree of polymerization (DP) of 4 and said enzyme being an α-glucanotransferase capable of cleaving α(1-4) glucosidic bonds and creating α(1-6) glucosidic bonds.

2. A method according to claim 1, wherein the syrup rich in oligosaccharides having a DP of 4 comprises at least 40%, preferably at least 45%, even more preferably at least 50% of oligosaccharides having a DP of 4.

3. A method according to claim 1 or 2, wherein the oligosaccharide-rich syrup having a DP of 4 has a dextrose equivalent (DE) greater than 20.

4. Method according to any one of the preceding claims, in which the substrate is at a concentration of between 50 g / L and 500 g / L, preferably between 100 g / L and 200 g / L of reaction medium.

5. A method according to any one of the preceding claims, wherein the α-glucanotransferase capable of cleaving α(1-4) glucosidic bonds and creating α(1-6) glucosidic bonds is the protein having the sequence SEQ ID No: 1 or a protein having at least 90% identity with the protein having the sequence SEQ ID No:

1.

6. A method according to any one of the preceding claims, wherein the enzyme is at a concentration of between 0.01 and 1 mg / mL of reaction medium, preferably between 0.05 and 0.5 mg / mL, even more preferably approximately 0.1 mg / mL of reaction medium.

7. Method according to any one of the preceding claims, characterized in that the substrate and the enzyme are brought together for a period of between 12 and 48 hours, preferably approximately 24 hours and / or at a temperature of between 20 and 40°C, preferably about 37°C and / or at a pH between 5 and 6.5, preferably about 5.

75.

8. Method according to any one of the preceding claims, characterized in that it further comprises a step of enzymatic treatment by an α-glucanotransferase capable of cleaving the α(1-4) glucosidic bonds and creating α(1-3) glucosidic bonds.

9. The method of the preceding claim, wherein the α-glucanotransferase capable of cleaving α(1-4) glucosidic bonds and creating α(1-3) glucosidic bonds is the protein having the sequence SEQ ID No: 2 or a protein having at least 90% identity with the protein having the sequence SEQ ID No:

2.

10. Mixture of a-glucans obtainable by the process according to any one of the preceding claims.

11. Mixture of a-glucans characterized in that it has: - a rate of hydrolyzable fibers less than 55%, preferably less than 50%, even more preferably less than 45%, - and / or at least 20% a(1-6) bonds, wherein the fiber content corresponds to the hydrolyzable fraction according to the AOAC 2002.02 method and the percentage of a(1-6) bonds represents the molar percentage of a(1-6) bonds relative to the total number of glycosidic bonds, measured by the Hakomori method.

12. Use of a mixture of a-glucans according to any one of claims 10 to 11 for the preparation of food for human or animal consumption.

13. Use of a glucanotransferase capable of cleaving α(1-4) glucosidic bonds and creating α(1-6) glucosidic bonds to reduce the digestibility of a mixture of α-glucans, said glucanotransferase having the sequence SEQ ID No: 1 or a sequence having at least 90% identity with the protein having the sequence SEQ ID No: 1.

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