Technical Field

The present invention relates to oat bran fractions and processes for producing oat bran fractions.

Background

β-glucans are polysaccharides of D-glucose monomers linked by β-glycosidic bonds, which occur naturally in some yeast, fungi, plants and bacteria, β-glucans occur in various forms, such as (l,3)-P-glucan, (l,4)-P-glucan, (l,6)-P-glucan, (1,3;1,6)-β- glucan and (l,3;l,4)-P-glucan. The designations (1,3), (1,4) and (1,6) refer to the type of bond found in the β-glucan, and designate the carbon atoms in the D-glucose monomers between which the β-glycosidic bond is formed. Some, but not all, β-glucans are water-soluble. (1 ,3; 1 ,4)-P-glucans are generally water soluble, at least at sizes below 2,000,000 Daltons. β-glucans are notably found in cereal grains, for example, wheat, barley, rye, and oat. Oats are a particularly good source of β-glucans, particularly (l,3;l,4)-P-glucan.

Within oat, β-glucans are found predominantly in the aleurone layer and sub- aleurone layers of the grain. In conventional methods for processing grain, the aleurone layer is generally removed with the bran, whilst the sub-aleurone layers are retained as part of the endosperm. Consequently, conventional methods of processing grain are not suitable for maximising the recovery of β-glucans from oats.

Compositions, particularly dried compositions comprising β-glucans, are increasingly used as a consumable ingredient, to impart the beneficial health properties of β-glucans to a variety of foods and beverages. In addition, liquid compositions comprising β-glucans have been shown to be useful in a variety of ways, including as a food additive, a nutritional supplement, in pharmaceutical compositions, in healthcare, for hair care, skin care and for use in cosmetics. Particularly with regard to skin care, compositions comprising β-glucan have been shown to reduce erythema, as well as acting as an anti-irritant, and can be used to provide relief from insect bites, β- glucan compositions can also be applied to sooth the skin, providing relief from sunburn, β-glucan compositions are also used as an emollient. The production of such compositions are known, and generally comprise an initial dry milling stage. This may be followed by a wet milling process and subsequent separation of components to produce a composition comprising β-glucans, for example as disclosed in EP 1 363 504 and EP 1 706 001. Alternatively, a dry milling process may be followed by process which makes use of alkaline extraction and alcohol precipitation; however, these processes suffer from being expensive. Further, consumers increasingly wish to purchase naturally produced products. In many countries, in order for a product to be labelled as natural, certain legal and/or regulatory requirements must be met. These often prescribe processes which may not be used in relation to the production of "natural" products. Alkaline extraction and alcohol precipitation are often cited as proscribed forms of processing for natural products, meaning that where alkaline extraction or alcohol precipitation is used to extract β- glucans from cereal grains, in many countries the resultant β-glucan may not be labelled as "natural". This means the resultant product is less commercially attractive.

A further problem with extraction methods based on alkaline or alcohol extraction is that there are often residual impurities which result in a β-glucan composition which is prone to hazing. Compositions prone to hazing are undesirable, and potentially unsuitable for a variety of uses, particularly for consumer products such as cosmetics and food. US2014/0066510 discloses a method of producing oat extracts which addresses this, but results in a composition with almost no β-glucan.

Different uses of β-glucan compositions may require or benefit from the provision of β-glucans having an average size in a particular range. A further drawback of the alkaline extraction and alcohol precipitation processes referred to above is that these processes do not provide the ability to control the size of the β-glucans in the resultant composition.

Consequently, there is an ongoing need for the effective and efficient production from oats of compositions comprising β-glucan.

Summary

According to a first aspect of the present invention, there is provided a process for producing an oat bran fraction, wherein: oat grains are dehulled; the resultant dehulled grain is subjected to a first milling; the milled grain is passed through a sifter; the small fraction from the sifter is passed to one or more first sieves, wherein the one or more first sieves have a mesh comprising one or more artificial fibres and a mesh size of between 300 and 700 μιη; and the retained fraction from the first sieve being passed through a final sieve comprising a mesh size of between about 150 and 200 microns, with the retained fraction of the final sieve comprising the oat bran fraction.

In an embodiment, the oats are not heat-treated prior to dehulling.

In an embodiment, the first milling comprises the use of a roller mill.

In an embodiment, the sifter is a horizontal sifter.

In an embodiment, the sifter comprises a mesh with size of between about 1.6mm and 1.8mm.

In an embodiment, the one or more first sieves is a rotary sieve.

In an embodiment, the one or more first sieves has a mesh size of between 330 and 420 μιη.

In an embodiment, the one or more first sieves has a mesh size of between 350 and 400 μm.

In an embodiment, the large fraction from the sifter is subjected to a second milling by a second mill; the fraction output by the second milling is passed through one or more second sieves; and the retained fraction from the one or more second sieves is passed to the final sieve. Optionally, the fraction retained by the one or more first sieves prior to being passed to the final sieve is subjected to the second milling with the large fraction from the sifter. Optionally, the second mill is a roller mill, and optionally the roller mill performing the second milling is configured to press the large fraction from the sifter but not the fraction retained by the first one or more sieves. Optionally, the one or more second sieves comprises a mesh comprising one or more artificial fibres and a mesh size of between 300 and 420 μιη. Optionally, the small fraction from the one or more second sieves is returned to the second mill; in another option the small fraction from the one or more second sieves is passed to a third sieve. Optionally, the retained fraction from the one or more second sieves prior to being passed to the final sieve is subjected to a third milling by a third mill; the fraction output by the third milling is passed through one or more third sieves; and the retained fraction from the one or more third sieves is passed to the final sieve; in a further option, the third mill is a roller mill. Optionally, the one or more third sieves comprises a mesh comprising one or more artificial fibres and a mesh size of between 300 and 420 um. Optionally, the small fraction from the one or more second sieves is returned to one of the second and the third mills.

In an embodiment, the oat bran fraction comprises between 15-30% of the endosperm of the original dehulled grains.

In an embodiment, the oat bran fraction constitutes between 30-55% of the original grain prior to dehulling. Optionally, the oat bran fraction constitutes between 35-45% of the original grain prior to dehulling; in another option, the oat bran fraction constitutes between 35-40% of the original grain prior to dehulling.

In an embodiment, the oat bran fraction comprises less than 45% starch.

Optionally, the oat bran fraction comprises less than 44% starch.

According to another aspect of the present invention, there is provided an oat bran fraction produced according to any of the above methods. Optionally, the oat bran fraction comprises a lower proportion of starch on a dry matter basis than an oat bran fraction produced by a process analogous to the first aspect of the invention listed above, or any of the embodiments of the first aspect in which: the oats are not heat- treated prior to dehulling; the first milling comprises the use of a roller mill; the sifter is a horizontal sifter; the sifter comprises a mesh with size of between about 1.6mm and 1.8mm; the one or more first sieves is a rotary sieve; the one or more first sieves has a mesh size of between 330 and 420 μιη; and/or the one or more first sieves has a mesh size of between 350 and 400 μιη; with the exception that in the analogous process the one or more first sieves has a mesh which does not comprise an artificial fibre. In a further option, the first milling in the analogous process comprises the use of a disk mill, and in a further or alternative option the first milling in the analogous process comprises the use of a vertical sifter.

Further features and advantages of the invention will become apparent from the following description of preferred embodiments of the invention, given by way of example only, which is made with reference to the accompanying drawings. Brief Description of the Drawings

Figure 1 shows an embodiment of a dry milling process according to the invention. Figure 2 shows another embodiment of a dry milling process according to the invention.

Figure 3 shows an embodiment of a downstream process for producing a β- glucan powder.

Detailed Description

The oats to be milled may be derived from one or more types of varieties of grain. In preferred embodiments the grains are not heat-treated.

The grain is dehulled via conventional means, for example via the use of peelers. Unhulled grain is then separated from the dehulled grain. This can be achieved by the grain being passed to a shaking table. Air classification may be applied to suck the hulls up and away from the dehulled grain. In one embodiment, the dehulled grain is permitted to comprise up to 16 unhulled grains per lOOg of dehulled grain. Preferably, the dehulled grain may be permitted to comprise up to 1% of unhulled grains per dehulled grain; a percentage of unhulled grains may be used, but this will decrease potential yields. Preferably, the number of unhulled grains per lOOg of dehulled grain is equal to or greater than 10, so as to avoid excessive loss of dehulled grains.

Preferably, at least 85% of the grain is dehulled in a single cycle through the peelers. The unhulled grains which are recovered from the process may be passed back to the peelers.

The unhulled grain is then milled. In one embodiment milling is performed via use of a disk mill. Preferably, the grains are milled to an extent sufficient to ensure that between about 20% and 25% of the endosperm is retained with the bran, as this provides a good balance between ensuring a high recovery of β-glucan whilst limiting the amount of starch retained in the bran. The space between the disks may be optimised depending upon the crop being milled. In one embodiment, the space between the disks in the disk mill is set to provide milling of the grain sufficient to ensure that between about 20% and 25% of the endosperm is retained.

In another embodiment the milling is performed by means of a roller mill. A roller mill will produce less variability than the disk mill. This allows for greater optimisation of subsequent sifting and milling, which enables greater precision in the subsequent enzymatic processes, due to greater consistency of the characteristics of the bran. In particular, the use of a roller mill decreases the likelihood of smaller oat grains passing through the mill and into the bran without being milled, which would otherwise increase the amount of starch in the bran.

In some embodiments the distance between the rollers in the roller mill may be determined on an ongoing basis. This has the advantage of being able to adjust for natural variances within the grain. In one embodiment, the distance can be determined by sporadically taking a sample of the fraction output by the roller mill and running it through a series of stacked sieves.

The milled grains are then optionally passed through a sifter. In one embodiment, the sifter is a vertical sifter. In one embodiment, the size of the mesh in the vertical sifter may be between about 1.6mm and 1.8mm, and preferably about 1.75mm. Alternatively a horizontal sifter may be used. It has been discovered that a larger gap between the mesh and the outer wall may be advantageous when milling oats as this reduces the clogging which may otherwise occur, due to the stickiness of the oats. A sifter with a larger gap may therefore require less cleaning when milling oats. Horizontal sifters tend to have a larger gap between the mesh and outer wall than comparable vertical sifters.

By passing the milled grain through a sifter, two fractions are produced, a small fraction and a large fraction. The large fraction is passed to a roller mill (which will be a second, distinct roller miller in embodiments in which the initial milling was conducted by a roller mill), wherein the roller mill presses the large fraction. Where a sifter is not used, the milled grain is passed to a roller mill.

The small fraction from the sifter is passed through one or more first sieves in order to remove the flour whilst retaining the small grain fractions. In some embodiments, one or more first sieves are rotary sieves. The first sieves have a mesh comprising nylon and/or other artificial fibres. An artificial fibre is one which does not predominantly comprise a naturally occurring fibre. Artificial fibres may be polymers produced from petrochemicals. The use of nylon or other artificial fibres can be advantageous due to the increased vibrations of the mesh, which prevents sticking. This is particularly advantageous when milling oats, as oats have a higher proportion of lipids in comparison to most other grains, and so are more prone to sticking. This means the mesh sizes for meshes comprising nylon and/or other artificial fibres can be smaller. Embodiments in which the first sieves comprise nylon and/or other artificial fibres may have a mesh with a size between about 300 and 700μιη, more preferably between about 310 and 600μιη, more preferably between about 320 and 500μιη, more preferably between about 330-400μιη, and more preferably about 350-370μιη. The ability conferred by the use of meshes comprising artificial fibres means that the ability to remove starch-containing flour is not impaired by clogging of the mesh, whilst ensuring that more of the β-glucan comprising material is retained. Consequently, an oat bran fraction with proportionally less starch, i.e. a lower percentage of starch on a dry matter basis, can be produced.

In some embodiments multiple first sieves may be used to ensure sufficient throughput of the small fraction. In some embodiments, two first sieves may be used.

In some embodiments the fraction retained by the one or more first sieves may then be passed to a final sieve. In other embodiments, the fraction retained by the one or more first sieves may then be passed to a further (third) sieve. In other embodiments, the fraction retained by the one or more first sieves then joins the large fraction stream from the sifter, before being passed to the roller mill. Preferably, the roller mill will be configured so as to press the large fraction, but not the fraction retained by the first sieves as pressing of the fraction retained by the one or more first sieves can reduce the β-glucan yield.

In some embodiments the distance between the rollers in the roller mill may be determined on an ongoing basis. This has the advantage of being able to adjust for natural variances within the grain. In one embodiment, the distance can be determined by sporadically taking a sample of the fraction output by the roller mill and running it through a series of stacked sieves. The desired profile may be determined based on the equipment used for downstream processing, for example wet milling, as the size profile of the contents of the fraction output roller mill can have an impact on the wet milling process.

The fraction output by the roller mill is then passed through one or more second sieves. Optionally, multiple second sieves may be used to improve throughput. Optionally two or more second sieves are used. In some embodiments a first second sieve may have a mesh size of about 1.6mm, and a second second sieve may have a mesh size of between about 350 and 400 microns. The use of a first second sieve with a larger mesh size than the second second sieve prevents blockage of the second second sieve. The first second sieve may also agitate or smash the bran so as to remove flour stuck to the bran. In an embodiment, the first second sieve is a roller mill.

In some embodiments, the small fraction from the one or more second sieves is then passed to the third sieve. In other embodiments, the small fraction from the one or more second sieves is then returned to the fraction retained from one or more first sieves and passes through the rotary mill again.

In embodiments in which at least one of the large fraction from the first sieve and the small fraction from the second sieve are passed to the third sieve, the third sieve will remove flour from the fraction, producing a coarse fraction which may then pass to the final sieve.

Optionally, the large fraction from one or more second sieves may pass through one or more repetitions of roller millers and one or more sieves. With each repetition, the small fraction from the one or more sieves is passed back to an earlier roller mill in the process; preferably the small fraction from the one or more sieves is returned to the fraction retained from one or more first sieves.

After the final repetition of milling and sieving, the large fraction retained by the sieve is passed through a final sieve, to remove any remaining flour. Preferably, the final sieve may comprise one or more artificial fibres. In some embodiments, the final sieve may have a have a mesh size of between about 150 and 200 microns; in some embodiments the mesh size of the final sieve may be between about 170 and 185 microns. The fraction retained by the final sieve is conveniently referred to as the oat bran fraction, but will comprise bran and parts of the aleurone layer and sub-aleurone layer.

In some embodiments, the bran fraction will constitute between 30 and 55%, and preferably between 35-45% of the original grain other than as flour. More preferably the bran fraction will constitute between 35-40% of the original grain other than as flour and the remainder may be between 28-35% husk and between 25-32% flour.

The oat bran fraction may then be processed in a number of ways.

Advantageously, the use of the above described dry milling process results in an oat- bran fraction with a lower proportion of starch. This enables increased efficiency in downstream processing, such as enzyme degradation, alkali extraction and alcohol precipitation. For example, in processes in which the starch is subjected to enzymatic degradation, a lower proportion of starch in the oat bran fraction enables a shorter period of enzymatic degradation to be utilised, which provides a more efficient overall process, both in terms of speed of production and cost of production, particularly where the process of enzymatic degradation occurs at an elevated temperature, as reducing the length of time for which an elevated temperature is maintained reduces the cost of processing. Reduced starch in the oat bran fraction also provides advantages following enzymatic degradation, as there will be less sugar in the slurry post-degradation. This enables more efficient separation of components within the slurry, and also more efficient drying of the components, as an excess of starch and starch derivatives, such as dextrins, maltodextrins and sugars, can cause clogging within the machinery used for separation; this is particularly evident where continuous processes, such as continuous centrifugal separators are utilised. The reduction in starch also means that less enzyme can be used in the process, thereby providing a cost saving. Less water may also be used in the process, which again results in efficiencies in heating, as a lower volume requires heating, and also provides an improvement in efficiency as less drying is required. With a reduction in starch smaller equipment can be used.

The ability of the above-described dry-milling process to reduce the proportion of starch in the oat bran fraction is shown in Table 1, below. Fractions 1-7 were produced using a process as described above, in which the initial milling was performed by a roller mill, a horizontal sifter was used, and first and second rounds of sieves with a further intermediate roller milling were utilised, with the meshes of the first sieves and second sieves comprising nylon with a mesh size of between about 300 and 420μιη. Fractions 8-17 were produced by a process similar to that described above, but a disk mill was used for the initial milling, a vertical sifter was utilised, and only a single round of sieving was used, in which a metal mesh with a mesh size of approximately 450μιη was utilised.

Fraction Number Mesh type used % starch in oat bran fraction on a dry matter basis 1 Nylon with a mesh size of 42.9 between about 300 and 420μιη

2 Nylon with a mesh size of 42.4 between about 300 and 420μιη

3 Nylon with a mesh size of 43.2 between about 300 and 420μιη

4 Nylon with a mesh size of 43 between about 300 and 420μιη

5 Nylon with a mesh size of 42 between about 300 and 420μιη

6 Nylon with a mesh size of 43 between about 300 and 420μιη

7 Nylon with a mesh size of 38 between about 300 and 420μιη

8 Metal with a mesh size of about 47

450μιη

9 Metal with a mesh size of about 48

450μιη

10 Metal with a mesh size of about 50

450μιη

11 Metal with a mesh size of about 50

450μιη

12 Metal with a mesh size of about 48

450μιη

13 Metal with a mesh size of about 46

450μιη

14 Metal with a mesh size of about 46

450μιη

15 Metal with a mesh size of about 50

450μιη 16 Metal with a mesh size of about 47

450μιη

17 Metal with a mesh size of about 48

450μιη

Given that the starting material, oat grains, are a naturally occurring product, there will be some inevitable natural variation in the levels of starch produced. Nevertheless, the figures in Table 1 demonstrate that the use of the herein described improved process produces an average proportion of starch in the oat bran fraction of 42% on a dry matter basis, as opposed to an average percentage of 48%, a reduction of 12.5%.

The oat bran fraction may comprise one or more forms of water-soluble β- glucans. In some embodiments, the β-glucan in the oat bran fraction may comprise one or more of (l,3)-P-glucan, (l,4)-P-glucan and (l,3;l,4)-P-glucan. In particular, the oat bran fraction may comprise ( 1 ,3 ; 1 ,4)-P-glucan.

Oat bran fractions with reduced starch according to the present invention may be used in a number of downstream processes.

In one embodiment, the oat bran fraction is subjected to a process of enzymatic degradation. The bran fraction is dispersed in water and treated with a starch degrading alpha-amylase enzyme.

In some embodiments, the bran fraction is mixed with water prior to the addition of any enzymes (although some enzymes native to the oat grain may already be present in the bran fraction). In some embodiments, this may be done in a separate vessel, such as a pre -reactor tank, to that in which enzymatic degradation will occur. The use of a separate vessel can provide greater control over the amount of bran fraction being subjected to enzymatic degradation, as in embodiments in which the bran fraction is added directly to the reaction vessel, a blockage or inconsistency in the rate in which bran is added can lead to greater variation in the end-product, particularly if the blockage or inconsistency is not noticed by the operator, for example if the blockage clears without operator intervention, and/or the inconsistency is only present for a short period of time. Alternatively, the alpha-amylase enzyme may be added at the same time as the water and bran; this may cause an increase in fat content in the downstream processes, and so may be done where an increase in fat in the beta-glucan stream is desired. Without wishing to be bound by any theory, it is possible that the mixing of the bran with water and alpha-amylase causes some beta-glucan molecules to come out of solution, which then bind to the fat molecules, whereas when the enzyme is not added until after the bran- fraction is mixed with water, the fat may bind to the protein and so is removed along with the protein. Where there is excess fat present in the beta-glucan stream, this can cause problems in drying the beta-glucan; for example where a drum drier is used, excess fat may cause the beta-glucan to fall off the drum.

When adding the water to the bran fraction, the water may be pre-heated, for example to a temperature of between about 85°C and about 95°C, e.g. to above about 90°C or to between about 92.5°C and about 95°C. This can increase the amount of beta- glucan revered, and may also reduce the binding of fat to beta-glucan and so reduce the level of fat in the downstream beta-glucan stream in embodiments in which that is desirable.

In embodiments in which the water and bran fraction are mixed prior to the addition of the alpha-amylase, and/or the water and bran fraction are mixed in a separate vessel, the mixing may be for a pre-determined period of time prior to the addition of the alpha-amylase and/or the movement of the resultant slurry to the reactor vessel. The pre-determined period of time may be for at least about 5 minutes, or at least about 10 minutes.

The alpha-amylase may be a thermostable alpha-amylase, and the enzymatic hydrolysis may be performed at temperatures of about 95°C or more. In some embodiments this may be followed by or combined with a second hydrolysis step using an enzyme, or combination of enzymes, from the group of amyloglucosidases and pullulanases. The second hydrolysis step may be performed at for up to 40 minutes and at a temperature of 55°C or greater. Where amyloglucosidase is used, the amyloglucosidase enzyme may be substantially cleaned of β-glucanase side activities prior to use, for example via a two-step procedure using anion exchange followed by hydrophobic interaction chromatography, the major protein band eluting from the hydrophobic interaction chromatography column being utilised as the cleaned enzyme.

One or more of the enzyme treatments are optionally performed in combination with aqueous wet-milling. For example, in some embodiments enzymatic hydrolysis may be performed in a series of reactor vessels, with a wet mill interspersed between the reactor vessels. Wet milling the slurry opens up new surfaces on which the enzymes can operate.

Following enzymatic degradation, the resultant slurry is separated. In some embodiments, this may be done by means of centrifugation in order to produce between 2 and 4 distinct layers, including an aqueous top-layer rich in β-glucans, and a lower layer containing proteins, oils and the insoluble fibrous portion of the grain. The aqueous top-layer rich in β-glucans may then be removed, for example via use of a decanter.

In some embodiments, the hydrolysate spontaneously separates, or is optionally separated centrifugally, into 3 distinct layers, a top-layer which is rich in soluble dietary fibres, particularly β-glucans, but containing little oil (<5.0%) or protein (<7%), a middle aqueous layer, and a lower phase containing most of the protein, oil and insoluble fibrous material from the milled grain.

The aqueous top layer can be removed via use of a decanter, for example a 2- phase or 3-phase decanter or other suitable device, yielding a soluble fraction which in some embodiments may contain at least 10 % (on a dry matter basis) β-glucans, along with maltodextrins, arabinoxylans, sugars and relatively low amounts of protein (<7%) and oils (< 5.0 %).

As an alternative to centrifugation into distinct layers, the solid part of the slurry may be removed from the liquid part. Any suitable means of separation may be used. In some embodiments this may be achieved via the use of continuous centrifugal separators, in which the slurry is passed into a rotating chamber such that the solid part of the slurry accumulates on the walls of the chamber, with the liquid part of the slurry passing out of the separator.

The protein is then removed from the liquid part of the slurry. In some embodiments, this may be achieved by passing the liquid part of the slurry to a decanter in order to remove the protein as a paste from the remaining aqueous solution of β- glucans.

A heat-treatment may be used to deactivate the enzymes used in the process. This may occur immediately after the completion of enzymatic degradation, or may occur at any point following the enzymatic degradation, including following centrifugation, separation or decantation. Applying a heat treatment immediately following enzymatic degradation may be preferred in some embodiments, as this will enable greater control of the degree of degradation.

The aqueous solution of β-glucan may comprise more than 20% β-glucan on a dry matter basis. In some embodiments, the β-glucan may have a molecular weight of at least 400,000 Daltons, at least 800,000 Daltons, or at least 1 ,300,000 Daltons.

The aqueous solution of β-glucan can optionally be further treated via enzymatic hydrolysis, for example using one or more enzymes from the groups of lichenase, cellulase, and xylanase, in order to reduce the size of the β-glucan and/or fine tune its properties, in a controlled manner.

In some embodiments, the aqueous solution of β-glucan may contain at least

10%) and up to 40%> β-glucan, and not more than 10%>, 7% or 5% protein, and less than 5.0%, 4.0%, 2.5%, 2.0%, 1. 5%, or 1.0% oil, on a dry matter basis.

Dextrins within the aqueous solution of β-glucan may then be removed. In some embodiments, this may be done via means of centrifugation, for example via stacked disc centrifuges, in which a layer comprising the β-glucan and a separate layer comprising the dextrins is formed. Alternatively, the dextrins may be separated by decantation, including centrifugal decantation, which in some embodiments may be a continuous process.

In some embodiments, the dextrins may be removed by the use of two separation means, for example two decanters or two centrifuges. The first separation means can be configured so as to separate the slurry into a first heavy phase comprising dextrins, and a first light phase with some heavy phase contamination, so that the first light phase comprises the beta-glucan and some dextrin. The first light phase may then be passed to the second separation means, which is configured so as to separate the first light phase into a second light phase comprising beta-glucan, and a second heavy phase with some light phase contamination, so that the second heavy phase comprises dextrin with some beta-glucan. The second heavy phase may then be passed back to the first separation means. This can improve the efficiency of beta-glucan recovery by reducing the amount of beta-glucan lost in the dextrin stream from between about 2-3% to about 0-1% or about 0.1-1%. Following the separation of the dextrins, the β-glucan solution may then be dried, for example via spray drying or roller drying. This produces a solid composition comprising β-glucan..

In some embodiments, the aqueous solution comprising β-glucan following removal of the protein, for example the aqueous solution of β-glucan containing at least 10% and up to 40% β-glucan, and not more than 10%>, 7% or 5% protein, and less than 5.0%), 4.0%), 2.5%o, 2.0%), 1.5%, or 1.0%> oil, on a dry matter basis, may then be subjected to further processing to produce a liquid composition with a lower percentage of β- glucan. The method comprises as a first step subjecting the mixture to at least one enzymatic treatment. The enzymatic treatment degrades at least a portion of at least one polysaccharides present in the mixture that is not β-glucan. This is followed by a second step of filtering the enzymatically treated mixture via means of membrane filtration. This results in a liquid β-glucan composition. This composition may be a solution, colloidal dispersion or a suspension. In some embodiments the composition will be a solution. In some embodiments the composition medium will be aqueous.

The aqueous solution comprising β-glucan following removal of the protein may be diluted in order to reduce the concentration of β-glucan, for example by the addition of water. In one embodiment, the dilution provides a concentration of β-glucan of approximately 1.5% or approximately 1.3%.

The optionally diluted aqueous solution comprising β-glucan following removal of the protein may be subjected to at least one further enzymatic treatment. Optionally, one or more enzymatic treatments may occur in a stirred reaction tank.

The enzymatic treatment is conducted in order to at least partially degrade one or more polysaccharides other than the β-glucan. Any enzyme capable of catalysing the cleavage of polysaccharide bonds may be used; for example one or more enzymes selected from the amylase and amyloglucosidase enzyme groups may be used, for example, a-amylase and β-amylase. Generally, enzymes which do not degrade the β- glucans are preferred, for example alpha-amylase; however, one or more enzymes which degrade β-glucans may be used either instead of or in addition to other enzymes which degrade at least one polysaccharide but do not degrade β-glucan. Enzymes which degrade β-glucan may be used when it is desired to reduce the average size of the β- glucan molecules. In order to control the resultant size of the β-glucan molecules, the enzyme which degrades β-glucan must be added for a pre-determined period of time prior to quenching the reaction. Where other enzymatic treatments which do not degrade β-glucan are being used, the treatment with an enzyme which degrades β- glucan may overlap with a portion of at least one other enzymatic treatment. Alternatively, the treatment with an enzyme which degrades β-glucan may occur separately from the other enzymatic treatments.

The composition may be heated so as to improve enzyme activity, preferably before addition of the enzyme. The temperature to which the solution is heated will be determined by the specific enzymes used. In some embodiments one or more thermostable enzymes may be used. Whilst many enzymes derived from mesophiles will undergo significant denaturation at temperatures of 55°C or more, with the rate of denaturation increasing with increased temperature, thermostable enzymes are enzymes which are more resistant to denaturation and so may retain effective, and in some cases optimal, activity at temperatures equal to or greater than 60°C, 70°C, 80°C, 90°C, 95°C or more. For example, thermostable alpha-amylases are commercially available which are functional at temperatures of 95°C and above. By using thermostable enzymes, the composition being subjected to enzymatic treatment can be heated to elevated temperatures such as 60°C, 70°C, 80°C, 90°C, 95°C or more. In addition to optimising enzyme activity, such elevated temperatures can reduce microbial contamination, and can also prevent enzymatic activity from other, undesired enzymes. Such undesired enzymes may be present as contaminants in the enzyme used for enzymatic treatment, or may be present as a residual element from the oat grain. The process also proceeds more quickly at elevated temperatures.

The pH of the composition may also be modified to improve enzyme activity. The desirability of any change to pH will be dependent on the enzymes used, but for example the pH may be modified from between 6 and 7 to between 3.5 and 5 or to between 4.5 and 5. A variety of means known in the art may be used to achieve this.

The enzymatic reaction should be allowed to proceed for a time long enough to sufficiently degrade at least one polysaccharide so as to reduce flocking in the final product, for example for at least 30 minutes, 45 minutes, 1 hour, 2 hours, or more. In general, a period of between 1 and 2 hours is used, dependent upon the degree of degradation required. Dextrins will cause flocking at a DP (degree of polymerisation, i.e. the number of monomeric units in the polymer), of between 7 and 12, or more. Consequently, where at least one polysaccharide in the composition other than β-glucan is a dextrin, the dextrin may be degraded to about 6DP, 5DP, 4DP or 1DP, and the enzymatic treatment proceeds for at least long enough to obtain this degree of degradation. In many circumstances, no flocking will occur when a dextrin is degraded to below 4-5DP, and so in some embodiments, the dextrins will be degraded to less than 5DP or less than 4DP. Likewise, where polysaccharides other than dextrins (or β- glucan) are present in the composition, the enzymatic treatment may be allowed to proceed for a time sufficient to degrade the polysaccharides to 6DP, 5DP, less than 5DP, 4DP, less than 4DP, or 1DP.

Once the enzymatic treatment has been allowed to proceed for a sufficient time, the enzymatic treatment should be stopped. This may be done by heating the composition to a temperature sufficient to denature the enzymes, for example, 80°C, 100°C, 120°C, 140°C or greater. The temperature to which the composition must be heated to denature the enzyme will be dependent upon the specific enzyme. For example a thermostable alpha-amylase may need to be heated to 140°C, whereas if amyloglucosidase is being used without a thermostable alpha-amylase, the composition may need to be heated to 80°C. In some embodiments, the heating of the composition may be via means of a heat exchanger. For example, the composition may be heated for approximately 15 seconds at the desired temperature using a heat exchanger. Known methods for quenching enzymatic reactions other than heating may also be used.

In some embodiments, prior to the enzymatic treatment, the composition may be heated to at least 135°C or more. This may be achieved, for example, via means of a heat exchanger. This enables the enzymatic degradation of resistant maltodextrins, which may otherwise not be degraded. The degradation of resistant maltodextrins prevents the small amount of flocking in the final product which may otherwise occur. In some embodiments, the composition is heated to at least 140°C, at least 150°C, or between 150°C and 160°C. In some embodiments, this heating is combined with a reduction in the pH of the composition to between about 1.4 and 2.0, and preferably to between about 1.6 and 1.8. This facilitates the opening out of the resistant maltodextrin chains, to aid with their degradation. However, the low pH is not suitable for all end uses of the product, and so is not used in all circumstances. In some embodiments, resistant maltodextrins are degraded by applying a high sheer force to the composition during the enzymatic treatment. In some embodiments, the treatment comprises alpha-amylase and a temperature of between 95°C and 109°C, preferably between 100°C and 109°C, and more preferably between 107°C and 109°C. In some embodiments the high sheer force is applied for a period of at least five minutes. In some embodiments the use of a high sheer force during enzymatic treatment may be in addition to an earlier heating step to degrade resistant maltodextrins. The application of a high sheer force may be achieved by any means known in the art.

Where the composition has been heated, whether to denature enzymes or enable degradation of heat resistant maltodextrins, the composition may be allowed to cool naturally prior to filtration. This allows the composition to settle, reducing its turbidity. This means a more efficient, less expensive, filtration process may be used. Alternatively, the composition may be filtered immediately after heating, but the greater turbidity of the composition makes the filtration process more expensive. The composition may be allowed to stand for at least two, at least four or at least five weeks.

The composition is then filtered. A filter of between 0.45-1.5μιη, optionally 0.8-1.Ομιη, may be used. Preferably, membrane filtration is used, although other means of filtration, for example sand filtration, may be used.

Before or after filtration, preservatives may be added to the composition; however, it is preferable for the preservatives to be added prior to filtration, as the warm, sugar rich composition is otherwise prone to microbial growth. Suitable preservatives comprise any of: phenoxyethanol (for example at a concentration of 0.2% to 1 %), which is sold under the brand name Euxyl 701; benezoate (for example sodium benzoate, for example at a concentration of about 0.2% to 0.8%); 1,2 hexanediol (for example at a concentration of about 0.4%), caprylyl glycol (for example at a concentration of 0.4%), glycerine (a combination of benzoate, 1,2 hexanediol, carpylyl glycol, and glycerine is sold under the brand SymDiol); sorbates (for example potassium sorbate); and rosemary extract. It may be preferable to use only preservatives which are certified as being "natural", in order that the final product can be labelled as natural, in accordance with the labelling laws of many countries. Natural preservatives which may be used comprise SymDiol; 3% glycerine; and rosemary extract. After filtration, and before or after any preservatives are added, the concentration of β-glucan in the composition may be adjusted by dilution. Products in which the final concentration of dry matter is between 1 and 8% may be produced. Generally, about one-third of the dry matter will be β-glucan and two thirds will be products resulting from the degradation of the other polysaccharides, e.g. sugars. Products with β-glucan concentrations of between about 0.35 and about 2.5% may be produced. However, gelling can occur in the product when β-glucan is present at a concentration of about 2% or more, and so compositions with a β-glucan concentration in the range of about 0.8 to about 1.8, and preferably about 1.0 to about 1.5% are preferred. The resultant product may have a viscosity of between 20-500 cps at 20°C, dependent upon the β-glucan content and the preservatives used. In some embodiments, the viscosity will be about 80-240 cps at 20°C, and in some embodiments of between 100-200 cps at 20°C. If a reduction in gelling is desired, this can be achieved through the use of anti-gelling additives, such as zwitterionic additives, and/or by using β- glucans with a lower molecular weight.

The resultant product is low in protein and oil and has good stability due to the reduction in flocking. In some embodiments, the resultant product will have a shelf life of at least 12, 18, 24, 30 or 36 months. Shelf life may be defined as a period during which there is no noticeable microbial growth, no hazing and no variation in viscosity.

In embodiments of the method, the process only comprises procedures and reagents which are deemed to be natural for labelling purposes, so that the resultant product can be labelled and marketed as a "natural product"; for example the resultant product may not contain parabens. The resultant product may be hypoallergenic.

The resultant product may be of use in foods, pharmaceuticals, cosmetics, hair care and skin care products.

The resultant product may be used to soothe skin. The resultant product may be used to reduce the appearance of skin redness, either alone or in combination with other skin care products such as retinol. The resultant product may be used to reduce the appearance of wrinkles and lines on the skin. The resultant product may be used to treat and/or provide relief from the symptoms of insect bites. The resultant product may be used to treat and/or provide relief from the symptoms of sun exposure, for example sunburn. The resultant product may be used as an ingredient in any of skin-care products, cosmetic products, and beauty products, for example: moisturisers, lotions, and creams, whether for application to any of the hands, face or body; sun-screens; after-sun formulations; eye serums; and soaps.

The resultant product may be used as an ingredient in mouth wash or toothpaste. The resultant product may be used as an anti-irritant. The resultant product may be used as an ingredient in any of: shaving products, for example shaving creams, shaving gels, and lotions; underarm products, for example deodorants and anti- perspirants; and wipes, such as baby-wipes.

The resultant product may be used to facilitate wound healing.

The resultant product may be used in hair care to: improve tensile hair strength; increase the glossiness of the appearance of hair; and/or to moisturise the scalp. The resultant product may be used as an ingredient in any of shampoos, serums and conditioners, for example leave-in conditioners and leave-in serums.

Reference will now be made to the specific embodiments depicted in the figures. Figure 1 displays an embodiment of a dry milling system, and consists of a bin

21 for storing oat prior to use. The grain is transported to peelers 22 which dehull the grain. An air classifier (not shown) separates the hulls from the dehulled grain. The dehulled grain move to a shaking table 23 to separate out remaining unhulled grains . The grain then passes to a first roller mill, 24, where it is milled. The milled grain then passes to sifter 25, to produce a large fraction and a small fraction. The large fraction is passed to second roller mill 27, whilst the small fraction is passed to first rotary sieve 26. First rotary sieve 26 enables flour to be removed from the small grain fraction, whilst the large fraction from this first rotary sieve passes to third rotary sieve 34.

The milled product of second roller mill 27 passes to a second rotary sieve 28. The small fraction from this second rotary sieve 28 is then passed to third rotary sieve 34. This third rotary sieve removes flour from the fraction passing through it, with the large fraction produced by the third rotary sieve passing to fourth rotary sieve, 31

The large fraction retained by second rotary sieve 28 passes to the fourth rotary sieve, 31. This removes flour from the fraction passing through it, with the large fraction produced by this fourth rotary sieve is the oat bran fraction, and is suitable for downstram processing, for example treatment by enzymatic hydrolysis. Figure 2 displays another embodiment of a dry milling system, and consists of a bin 21 for storing oat prior to use. The grain is transported to peelers 22 which dehull the grain. The hulls and dehulled grain move to a shaking table 23 to separate the hulls from the grain.

The grain then passes to a first roller mill, 24, where it is milled. The milled grain then passes to horizontal sifter 25, to produce a large fraction and a small fraction. The large fraction is passed to second roller mill 27, whilst the small fraction is passed to first rotary sieve 26. First rotary sieve 26 enables flour to be removed from the small grain fraction. Having passed through first rotary sieve 26, the small grain fraction is then also passed to second roller mill 27. The milled product of second roller mill 27 is then passed to a second rotary sieve 28. The small fraction from this second rotary sieve 28 is then returned to the small grain fraction retained by first rotary sieve 26 before being passed into second roller mill 27.

The large fraction retained by second rotary sieve 28 is then passed to third roller mill 29. The milled product of third roller mill 29 then moves to third rotary sieve 30. The small fraction produced by third rotary sieve 30 is then passed back to the stream comprising the retained small grain fraction from first rotary sieve 26, before being passed to second roller mill 27.

The large fraction retained by third rotary sieve 30 is then passed to a fourth rotary sieve, 31. This removes flour from the large fraction. The retained large fraction, is the oat bran fraction, and is suitable for downstream processing, for example treatment by enzymatic hydrolysis.

The oat bran fraction produced by the means depicted in Figure 1 or Figure 2 may then be transferred to a wet system as depicted in Figure 3, where it is introduced in a reaction vessel 11 , together with the enzymes used and water to provide a slurry. A pH control sensor (not shown) is applied to the reaction vessel as well as a heating jacket or other temperature controlling means (not shown). The reacted mixture is transferred via a wet-mill 18 and a heat exchanger 12 to a separator 13 in the form of a decanter, where the top fraction/layer is transferred to a further reaction vessel 14, where the top layer is mixed with water to wash the product by separating of any entrapped protein being removed in a decanter 15. The β-glucan comprising solution then passes to decanter 16 at which point dextrins are removed, before being passed to drier 17, to dry the solution to produce a β-glucan powder.

The above embodiments are to be understood as illustrative examples of the invention. Further embodiments of the invention are envisaged. It is to be understood that any feature described in relation to any one embodiment may be used alone, or in combination with other features described, and may also be used in combination with one or more features of any other of the embodiments, or any combination of any other of the embodiments. Furthermore, equivalents and modifications not described above may also be employed without departing from the scope of the invention, which is defined in the accompanying claims.