Process for the industrial preparation of a hydrolysate of vegetable fiber of deproteinated (deglutinated) wheat having an hypoglycemic action and its uses in human and animal food

Abstract

A process is described for the industrial preparation of a hydrolysate from deproteinized (deglutinated) cereals, in particular from micronized cereal fractions, as well as its uses in foods for humans and feed for animals. This process allows to obtain a water-soluble hydrolysate containing a high percentage of pentosans with a low molecular weight which therefore offers a high bioavailability of soluble fibre and, at the same time, low protein content, in particular gluten content. This allows to overcome the disadvantages connected with high intake of wholemeal products while still benefiting from the nutritional components thereof.

Description

[0001] “PROCESS FOR THE INDUSTRIAL PREPARATION OF A HYDROLYSATE OF VEGETABLE FIBER OF DEPROTEINATED (DEGLUTINATED) WHEAT HAVING AN HYPOGLYCEMIC ACTION AND ITS USES IN HUMAN AND ANIMAL FOOD”

[0002] DESCRIPTION FIELD OF THE INVENTION

[0003] The present invention relates to a process for the industrial preparation of a hydrolysate from deproteinized (deglutinated) cereals, in particular from micronized cereal fractions, as well as its uses in human and animal food.

[0004] BACKGROUND ART

[0005] The fibre for food use (or “dietary fibre”, DF) have been identified as fundamental components of a healthy diet and for this reason, the current trend is to increase the content of fibre in food products. According to its solubility in water, DF is classified into soluble dietary fibre (SDF) or insoluble dietary fibre (IDF). The sum of the amounts of IDF and SDF is the total dietary fibre (TDF) content. The physical-chemical characteristics of fibre include fermentability, solubility and viscosity and these properties not only influence fermentation, but also the therapeutic effects of consumption thereof. Insoluble fibre, such as cellulose, is poorly fermented by the gut microbiome but the presence thereof in the diet increases intestinal transit speed, thereby reducing the amount of time available for the bacterial fermentation of undigested food in the colon. Soluble fibre, such as arabinoxylans, feature high solubility and viscosity which translates into unique therapeutic effects, such as glycaemic control, body weight control, increased satiety and lower levels of cholesterol in the blood.

[0006] It is known that cereals contain high amounts of soluble fibre (Arabinoxylans), but also significant amounts of proteins, in particular gluten. Gluten-free products generally have a high glycaemic index because they are formulated with ingredients with a high starch or sugar content: the enrichment thereof with hypoglycaemic soluble fibre would be optimal to enhance the impact of these products on consumers' health.

[0007] With a total annual harvest of approximately 770 million tonnes, corn is one of the most widely grown crops in the world. The majority of corn crops are intended for the production of white flour, which is produced by means of a method wherein the starchy endosperm is separated from the other parts of the com, thereby obtaining a refined product containing solely tiny amounts of minerals and dietary fibre.Wheat bran, defined as the external layers of the grain of corn which are separated from the other parts of the grain by milling, constitutes approximately the 15% of the grain and has an estimated annual production volume of 150 million tonnes. Wheat bran contains different important components such as fibre, minerals, and bioactive compounds which can be added to drinks and foods to enhance the nutritional aspects thereof.

[0008] Arabinoxylan (AX) is a non-starch polysaccharide dietary fibre which is present in cereals such wheat, maize, rice, rye, oats and barley, and is utilized as a functional component in bakery products due to the properties thereof, such as the ability to influence bonding with water, the rheology of dough, and the retrogradation of starch.

[0009] The molar mass of AX influences the chemical-physical properties thereof and is a strong indicator of the thickening capacity of arabinoxylan. The molar mass is influenced by the AX extraction method, indeed soluble AXs tend to have a lower molar mass than insoluble AXs. AX from wheat endosperm has a higher molar mass than AX from wheat bran and it is known that molar mass can also vary between the different layers of bran. AX with a high molar mass can be reduced enzymatically to produce arabinoxylans with a low molar mass with specific functions.

[0010] Different studies confirm the positive effects of AX from wheat on humans, such as the strong capacity to reduce postprandial glucose and insulin responses, the influence of the cholesterol on the metabolism, the protective action against oxidative stress and the reduction in the risk of developing cardiovascular diseases. The effects of the AX on health are linked to the structure thereof, in particular to the molar mass and at the degree of substitution. The effect on the reduction of cholesterol of the non-starch polysaccharides appears to be correlated with viscosity and molar mass, indeed a structure which is more integral due to a higher molar mass and a lower degree of substitution makes polysaccharides less accessible to human enzymes, influencing the effect thereof on metabolism. However, it has been demonstrated that AXs with low molar mass have the potential to enhance tolerance to glucose and have a prebiotic effect. Wheat bran features a cell wall characterized by a complex matrix and this makes the extraction of AX challenging and, for this reason, different processes have been developed to increase extraction efficiency.

[0011] During AX extraction, it is possible to utilise different methods for separating the AX from the cell wall matrix. As AX is bonded to the cell wall matrix of wheat bran covalently and non-covalently, in the past, more aggressive chemical methods were generally utilized forextraction, such as extraction with alkalis. During extraction with alkalis, the alkaline conditions release the AX from the complex cell wall matrix of bran, making the alkaline extraction method one of the most common isolation methods utilized for the extraction of AX from wheat bran. Various different alkaline solutions are utilized for extraction, including sodium, potassium, calcium hydroxide, hydrogen peroxide and barium ions. This method, when implemented for long periods of time at temperatures of around 80°C, deactivates the antioxidant capacity of the ferulic acid bonded to the Arabinoxylan molecules, reducing the bioactive effect thereof.

[0012] Over the course of the last few years, various alternative methods of extraction have also been developed, which utilise water, enzymes and physical treatments. The choice of the extraction method influences the extraction efficiency, but also the properties of the AX and the majority of these methods have a complexity which is difficult to transfer to an industrial level.

[0013] Indeed, the methods proposed so far usually combine different pre-treatments, extraction methods, and AX purification steps in an attempt to increase yield and final purity, however, they are, overall, scarcely cost-effective and scarcely sustainable during the industrial scale-up. Although AX is, for the main part, bonded to the hydro-repellent matrix of the cell wall, water subcritical extraction remains one of the most common methods used for wheat bran, thanks to the plasticity and the low cost thereof. Subcritical water extraction (SWE) is a hydrothermal treatment which utilises pressure to keep water in the liquid phase at high temperatures (100-374 °C). Extraction yields are somewhat low (<20% of the extraction yields from bran and from arabinoxylans) and the method is long and consists of different steps at temperatures ranging from 100 °C to 180 °C and pHs ranging from 5 to 9. Often, to increase the extraction yield, prior to the subcritical water extraction method, destarching or deproteinization treatments are carried out, thereby further extending the extraction times and costs.

[0014] With ultrasonication, sound energy within the human hearing range (> 20 kHz) is applied to the wheat samples. The mechanical energy which is generated with this method facilitates the release of both more available extracts and less extractable components of the cell wall with shorter treatment times and lower temperatures. There is no evidence for the hypoglycaemic effect of arabinoxylans extracted with this method.

[0015] At present, microwave treatment of wheat bran has not yet been studied, but it has been observed that microwave-assisted extraction improves the AX extraction yield from other cereal sources. Unlike with the mechanical sound waves utilized in ultrasound treatment,microwave treatment utilises electromagnetic waves with a frequency of between 300 MHz and 300 GHz. As microwaves mainly cause heating, the increase in the performance of AX originating from microwave-assisted extraction is very probably due to an increase in the temperature during treatment. Microwave treatment has proved to be a useful method for more efficient and controlled heating, reducing the extraction times when utilized for the extraction of AX from barley skins.

[0016] It has been known for some time that the reduction of the dimensions of the particles of wheat bran by milling influences both the composition of the bran and AX extraction, above all if subjected to enzymatic attack.

[0017] Enzymatic extraction is a natural, sustainable alternative method for isolating AX in which the solubility of AX from wheat bran is increased through the enzymatic degradation of the main structure of xylan. Nevertheless, with respect to alkaline extraction, enzymatic extraction results in lower extraction yields, probably due to the endogenous enzymatic inhibitors in the bran and in the partially crystalline structure of lignocellulose. Furthermore, enzymatic treatment also influences the molecular structure by decreasing the molar mass by 10-fold with respect to alkaline treatment, but at the time preserves ferulic acid, the high capacity to reduce postprandial glucose and insulin responses and antioxidant functions.

[0018] The object of the present invention is therefore to find an arabinoxylan extraction process which overcomes the prior art drawbacks as above discussed and, in particular, which is adequately industrially scalable, both economical and sustainable, and allows of satisfactory final yield and purity to be obtained without compromising the biochemical functions of the extract itself. SUMMARY OF THE INVENTION

[0019] Said object is achieved by a process for the industrial preparation of a deproteinized hydrolysate from cereals, as stated in Claim 1.

[0020] In a further aspect, the present invention concerns a deproteinized hydrolysate obtainable by said process.

[0021] In a still further aspect, the present invention concerns dietary compositions, food supplements and dietary products comprising said deproteinized hydrolysate.

[0022] In a still further aspect, the present invention concerns a process for the preparation of a phytocomplex which envisages the use of said deproteinized hydrolysate.

[0023] In a still further aspect, the present invention concerns the use of the hydrolysate and of the products containing said hydrolysate, including gluten-free products, to reduce the glycaemicindex, in particular in the treatment of subjects, including those with coeliac disease, suffering from diseases such as diabetes, metabolic syndrome, obesity, and cardiovascular diseases, in which the glycaemic index is above the normal range.

[0024] DETAILED DESCRIPTION OF THE INVENTION

[0025] The invention therefore relates to a process for the industrial preparation of a hydrolysate from cereals, which has a low protein content and a high arabinoxylan content, said process comprising the following steps:

[0026] i) providing a micronized cereal fraction (< 300 microns) and transferring the same to a reactor equipped with a stirrer,

[0027] ii) adding water having a temperature of 40-60°C, and mixing until a first homogeneous mixture is obtained,

[0028] iii) adjusting the pH to 9-11 and maintaining with stirring for about one hour, iv) separating the water in which proteins are dissolved, by means of a horizontal axis centrifuge with an adjustable impeller, from the cereal fraction thus deproteinized, v) transferring the deproteinized cereal fraction back to the reactor equipped with a stirrer,

[0029] vi) adding water up to a weight ratio of 1: 1 to 1:5 (deproteinized cereal fraction: water) thus obtaining a second homogeneous mixture,

[0030] vii) adding to the mixture thus obtained up to 2 wt%, based on the weight of the second mixture, of an enzymatic complex consisting of:

[0031] a) xylanase, or

[0032] b) xylanase, amylase, and glucanase,

[0033] and leaving to react for at least 6 hours at a temperature of 45 -65 °C and a pH of 3-6, viii) deactivating the enzymatic complex of step vii), by increasing the temperature to 80-90°C for at least 5 minutes,

[0034] ix) separating the liquid component from the solid component obtained at the end of step viii), by means of a horizontal axis centrifuge with an adjustable impeller, while retaining the liquid component, i.e. the hydrolysate from the cereal fraction thus further deproteinized,

[0035] x) concentrating the hydrolysate by means of:

[0036] a) a stirred film evaporator, adding up to 0.05wt% of proline-specific endopeptidase, thereby obtaining a concentrated hydrolysate having a dry matterresidue of 15-25 °Brix, containing < 20 ppm gluten,

[0037] or

[0038] b) a falling film evaporator, thereby obtaining a concentrated hydrolysate having a dry matter residue of 25-35 °Brix, containing 1000-2500 ppm gluten, and

[0039] xi) drying the concentrated hydrolysate, thus obtaining a powdered hydrolysate comprising 15-40wt% of arabinoxylans and 5-9wt% of proteins.

[0040] As will be seen herein below, the industrial process of the invention not only allows to obtain a hydrolysate which is advantageously enriched with pentosans having medium and low molecular weight, and in particular arabinoxylans, thus a hydrolysate enriched with the soluble fraction of the cereal, but also has a low protein content (for the sake of brevity, referred to as “deproteinized”), as the over 80% and preferably over 90% of the proteins initially present in the cereal have been removed, and especially with a low of gluten content or even devoid of gluten.

[0041] The determination of the pentosans, and therefore of the arabinoxylans, is based on a phloroglucinol-based colorimetric method which is rapid and reproducible (S. G. Douglas, “A rapidmethod for the determination of pentosans in wheat flour”, Food Chemistry, 7, 1981, 139-145) using D-xylose at 510-552 nm as reference standard. As the method envisages high-temperature acidic hydrolysis, all the pentosans are counted regardless of their degree of polymerization.

[0042] The determination of the proteins is based, instead, on the Dumas Method, also known as the combustion method, which guarantees rapid results, ease of use, and safety. The process is based on the combustion of the organic material, which is cleaved into water, carbon dioxide, oxygen, and nitrogen. The water, carbon dioxide, and oxygen are trapped so as to obtain free nitrogen. The total nitrogen content is measured with a thermal conductivity detector.

[0043] The determination of the gluten is performed with the “R5 Mendez ELISA” method, which contains RS sandwich antibody, classified as Type I according to the Codex Alimentarius, which is therefor a reference method

[0044] In step i) of the industrial process of the invention, a micronized cereal fraction (< 300 micron) is provided and then transferred to a reactor equipped with a stirrer.

[0045] With “Cereal”, it is meant wheat, barley, rice, rye, buckwheat, maize, oat, sorghum, millet, or a mixture thereof. In preferred embodiments, said cereal comprises wheat. More preferably,said cereal is wheat.

[0046] With “Micronized fraction”, it is meant a fraction with a particle size of < 300 micron obtained by milling or husking and subsequently sieving cereals.

[0047] Said reactor equipped with a stirrer is preferably a metal vat with a net capacity of between 40 and 80 hl, insulation designed to raise the thermal exchange coefficient with low levels of thermal loss and a stirrer consisting of a central shaft with a multi-blade stirrer. The uniform stirring provided by the stirrer optimises enzymatic action during step vii), which follows, by facilitating contact between the enzyme and the molecular complexes to hydrolyse which are present in the micronized cereal fraction.

[0048] In step ii) of the industrial process of the invention, water is added having a temperature of 40-60°C, and is mixed until a first homogeneous mixture is obtained.

[0049] Preferably, the temperature of the water is about 50°C.

[0050] Preferably, water is added to a weight ratio of between 1:1 and 1:5 (cereal fraction: water). In step iii) of the industrial process of the invention, the pH is adjusted to 9-11 and said first mixture is kept stirred for approximately one hour. The increased pH promotes the solubilization of the proteins in water.

[0051] In the step iv) of the industrial process of the invention, the water in which the proteins are dissolved is separated from the thus deproteinized cereal fraction by means of a horizontal axis centrifuge with adjustable impeller.

[0052] The horizontal axis centrifuge, also known as a centrifuge decanter, consists of a cylindro-conical drum for continuous separation, which rotates around a horizontal axis at a high number of revolutions per minute so as to apply the centrifugal force needed to produce the solid / liquid separation, a screw feeder which rotates with the drum at a certain differential velocity, a drive unit which transmits the necessary force to those rotating parts, and the frame (body) which transports all those parts mentioned above.

[0053] In operating terms, the rotation of the drum is managed by a main motor connected to the horizontal shaft and the extremely high centrifugal force which is generated in the interior thereof is proportional to the rotation velocity and the diameter of said drum. The product to separate enters via the feeder pipe and moves into the specific diffuser, which conveys said product to the centre of the drum, where it is rotated. The centrifugal force generated is responsible for the solid / liquid separation. As mentioned, the screw conveyor rotates with a differential velocity with respect to the drum, and conveys the deposited solid substancestowards the tapered conical end of the drum.

[0054] The impeller, or rotor, is a rotary part which is present in fluid-powered rotary machines. The “impeller eye” is the fluid intake point. The diameter of the impeller eye determines the intake area available for the supply of said fluid.

[0055] For the purposes of the present invention, the horizontal axis centrifuge separates the liquid component containing the proteins and the natural surfactants, while the solid component sediments. Said first homogeneous mixture is then fed into the centrifuge at a constant flow rate, while the adjustment of the diameter of the impeller eye permits rapid, accurate adjustment of the level inside the drum. In this step, the adjustment of the system is fundamental to ensure as many proteins and antioxidants as possible are extracted from the micronized fraction, but at the same time as little soluble fibre (Arabinoxylans) as possible.

[0056] The optimal combination of the adjustment of the velocity of the ingoing mixture and of the impeller eye allows to eliminate a consistent fraction of natural proteins and surfactants, without reducing the extractable Arabinoxylas content. Therefore, preferably, the horizontal axis centrifuge operates at a flow rate of 2.5-3.5 m3 / hour, the drum rotation velocity is 20-30% lower than the screw feeder rotation velocity, and the impeller eye is set at a diameter of 150-200 mm. More preferably, the drum rotation velocity is 3,500-4,500 revolutions per minute, and still more preferably 4,000-4,500 revolutions per minute.

[0057] This first part of the process, in particular owing to the combination of the pH increase in step iii), which promotes the solubilization of the proteins, and the use of the horizontal axis centrifuge in step iv), the protein content is drastically reduced, without significantly impacting the content of Arabinoxylans. In the protein solubilization water, there also remains a portion of natural surfactants amounting to 7-9 mg / l. The natural surfactants generate foam during the concentration phase and therefore the elimination thereof from the hydrolysate is functional to the successful outcome of the process and enhances the overall extraction yield.

[0058] Downstream of step iv), i.e. the separation step, the solid component preferably has a moisture content of 20-30%.

[0059] In step v) of the industrial process of the invention, the deproteinized cereal fraction is transferred back to the reactor equipped with a stirrer.

[0060] In step vi) of the industrial process of the invention, water is to the reactor added up to a weight ratio of 1:1 to 1:5 (deproteinized cereal fraction: water) thus obtaining a second homogeneous mixture.Preferably, the pH of said second homogeneous mixture is lowered to 3-6.

[0061] More preferably, citric acid is added to lower the pH.

[0062] In step vii) of the industrial process of the invention, up to 2 wt%, based on the weight of the second mixture, an enzymatic complex consisting of the following components is added to said second mixture:

[0063] a) xylanase, or

[0064] b) xylanase, amylase, and glucanase,

[0065] and left to react for at least 6 hours at a temperature of 45-65°C and a pH of 3-6.

[0066] Preferably, said xylanase is endo-l,4-beta-xylanase.

[0067] Preferably, said amylase is alpha-amylase.

[0068] Preferably, said glucanase is endo-l,3(4)-beta-glucanase.

[0069] In some preferred embodiments, in step vi), the cereal fraction and water are in weight ratio ranging from 1:1.5 to 1:3.

[0070] In further preferred embodiments, in step vii), the enzymatic complex is added in an amount up to 1 wt%, based on the weight of the second mixture. In the most preferable embodiments, in step vii), the enzymatic complex is added in an amount up to 0.1-0.7 wt%, based on the weight of the mixture.

[0071] In still further preferred embodiments, in step vii) the mixture is left to react for 10-20 hours at 45-60°C.

[0072] In particularly preferred embodiments, in step vii) the enzymatic complex b) consisting of xylanase, amylase, and glucanase is added.

[0073] In step viii) of the industrial process of the invention, the enzymatic complex of step vii) is deactivated by means of thermal treatment, i.e. by increasing the temperature to 80-90°C for at least 5 minutes.

[0074] Preferably, deactivation occurs at approximately 85°C for approximately 15 minutes.

[0075] In step ix) of the industrial process of the invention, the liquid component is separated from the solid component obtained at the end of step viii) by means of a horizontal axis centrifuge with an adjustable impeller, while retaining the liquid component, i.e. the hydrolysate from the cereal fraction thus further deproteinized.

[0076] Preferably, the horizontal axis centrifuge operates at a flow rate of 2.5-3.5 m3 / hour, the drum rotation velocity is 20-30% lower than the screw feeder rotation velocity, and the impeller eye is set with a diameter of 150-200 mm. These settings make it possible to reach an optimalextraction of soluble fibre (arabinoxylans) from the cereal fraction, succeeding in reaching an arabinoxylan yield of more than 20%.

[0077] More preferably, the drum rotation velocity is 3,500-4,500 revolutions per minute, and still more preferably 4,000-4,500 revolutions per minute.

[0078] In step x) of the industrial process of the invention, the hydrolysate is concentrated by means of:

[0079] a) a stirred film evaporator, adding up to 0.05 wt% of proline-specific endopeptidase, thereby obtaining a concentrated hydrolysate having a dry matter residue of 15-25° Brix, containing < 20 ppm gluten,

[0080] or

[0081] b) a falling film evaporator, thereby obtaining a concentrated hydrolysate having a dry matter residue of 25-35° Brix, containing 1000-2500 ppm gluten.

[0082] The concentration by means of a stirred film evaporator is well suited to the concentration of a highly viscose thermosensitive hydrolysate, and working in batches allows to meter the enzyme with respect to the entire volume of the centrifugate, the temperature reached by the liquid, preferably comprised with a range of 30 and 50 °C, permits the activation of the enzyme and the proteolytic and deglutinating function thereof. Therefore, the variant a) in step x) must be implemented when one wishes to obtain a gluten-free concentrated hydrolysate, since European and USA standards define products which contain < 20 ppm of gluten as “gluten-free”.

[0083] Alternatively, if it is not necessary to obtain a deglutinated product, it is possible to implement variant b) of step x). The concentration by means of a falling film evaporator takes place inside a long-tube vertical evaporator, which is suitable for viscose liquids which do not generate scale. The centrifugate is supplied continuously and permits fast transit of the liquid through the inside of the evaporator. This enables rapid concentration of the hydrolysate to a 25-35°Brix concentration of dry residue, thereby reducing the formation of acetic acid that typically occurs during concentration of these hydrolysates and limiting the presence thereof to levels < 2000 ppm.

[0084] Finally, the industrial process of the invention comprises a desiccation step xi), in which the concentrated hydrolysate is desiccated, thereby obtaining a powder comprising 15-40 wt% of arabinoxylans and 5-9 wt% of proteins.

[0085] Preferably, the desiccated hydrolysate obtained from step xi) comprises 20-30 wt% of arabinoxylans and 5-7 wt% of proteins.Preferably, this desiccation is achieved by spraying (referred to as spray drying) or by lyophilization, or by vacuum desiccation with non-ionising electromagnetic waves.

[0086] Preferably, the concentrated hydrolysate in step x) is moved through a heat exchanger, which lowers the temperature thereof from 30-50°C to 10-20°C. The concentrated hydrolysate is then preferably stored in chilled steel vats at a temperature ranging between 5 and 10°C.

[0087] The desiccation step is facilitated by the reduced natural protein and surfactant content, thereby advantageously allowing the complete elimination of the use of processing aids and making it possible to obtain a cereal hydrolysate which is 100% pure, i.e. not contaminated with desiccation aids.

[0088] Furthermore, the industrial process of the invention advantageously allows to re-use those components which are typically discarded.

[0089] The solid component which is separated in step ix), i.e. the spent plant matrix which contains, mostly cellulose and lignin, can be advantageously utilized as a source of insoluble fibre for food for humans or utilized as a base for the extraction of polyphenolic complexes with a high antioxidant capacity, or put to use as feed for animals either as is or, possibly, in granular or pellet form. Alternatively, the spent plant matrix can find appropriate use as a substrate for the growth of microorganisms, for example, those of the Trichoderma species, which are useful in agriculture, for example in the protection of what are known as pruning wounds or as anti-phytopathogenic agents. The liquid separated in step iv) can be utilized as a source of hydration and protein supplementation for pigs, given the protein content thereof and the microbiological profile thereof.

[0090] The process of the invention is therefore particularly advantageous since it uses an easily available plant matrix as raw material and all the resulting waste materials have a designated use, thus eliminating overall waste.

[0091] In a further aspect, the present invention furthermore concerns a deproteinized hydrolysate obtainable by the process described above. The elimination of the proteins from the hydrolysate allows to increase the soluble fibre titre and increase the efficiency thereof with the same amount; the further elimination of the gluten furthermore allows to exploit cereals which are naturally rich in soluble fibre but have been used little due to the presence of gluten, which is an allergen. This way an advantageously water-soluble hydrolysate is obtained.

[0092] In certain embodiments, said deproteinized hydrolysate comprises 15-40 wt% of arabinoxylans,the step x) of the process. More preferably, the hydrolysate comprises 20-30 wt% of arabinoxylans, 5-7 wt% of proteins and < 20 ppm of gluten.

[0093] In other embodiments, said deproteinized hydrolysate comprises 15-40 wt% of arabinoxylans, 5-9 wt% of proteins, and 1000-2500 ppm of gluten, as the hydrolysate is obtained with variant b) of the step x) of the process. More preferably, the hydrolysate comprises 20-30 wt% of arabinoxylans, 5-7 wt% of proteins and 1000-2500 ppm of gluten.

[0094] In both variants, the hydrolysate of the invention is therefore advantageously a source of soluble fibre which is essentially devoid of lignin and cellulose, which therefore does not determine irritable bowel phenomena and consequent meteorism and abdominal pains. Indeed, the reduced protein content make it more tolerable for people with a wheat intolerance.

[0095] Furthermore, in the variant with a gluten content of < 20 ppm, the hydrolysate allows the use thereof in food products intended for people with coeliac disease or who are intolerant to cereal proteins, who therefore have little access to the fibrous fraction thereof and are potentially at risk of hyperglycaemia and diabetes due to high intake of starchy and sugary products.

[0096] From the above, it is clear that the object of providing a product with a high bioavailability of soluble fibre, i.e. the deproteinized hydrolysate, which makes its possible, at the same time, to reduce the disadvantages connected with a high intake of commonly known wholemeal products.

[0097] Therefore, in a still further aspect, the present invention concerns dietary compositions, food supplements and dietary products, which may also be gluten free, comprising said deproteinized hydrolysate.

[0098] In particular, said dietary product can be an edible product, chosen from the following products: bakery products, feeds, alcoholic beverages, non-alcoholic beverages, energy drinks, diet bars, edible oils, breakfast cereals, fresh pasta, dried pasta, yogurt, ice cream, fruit juices and desserts, including sugar and chocolate.

[0099] Preferably, these dietary compositions, food supplements, and dietary products contain 1-5 wt% of the deproteinized hydrolysate of the present invention.

[0100] In a still further aspect, the present invention concerns a process for the preparation of a phytocomplex which envisages the use of said deproteinized hydrolysate, in addition to phytocomplexes thus obtained.

[0101] In particular, the process for the preparation of a phytocomplex comprises the following steps:

[0102] A) preparing a fermentation broth based on the deproteinized hydrolysate describedabove,

[0103] B) stabilising the fermentation broth at a pH of 3-6.5,

[0104] C) inoculating the fermentation broth with a first mother culture of at least one microorganism selected from Komagataeibacter xylinus, Komagataeibacter swingsii, Komagataeibacter rhaelicus. and mixtures thereof, or with a second mother culture of at least one microorganism selected from Streptococcus thermophilus, Lactobacillus debruecki bulgaricus, Lactobacillus helveticus, Lactobacillus plantarum, Lactobacillus casei, and mixtures thereof,

[0105] D) leaving the broth to ferment,

[0106] E) inactivating the fermented broth, and

[0107] F) purifying the inactivated fermented broth to obtain a phytocomplex.

[0108] Preferably, the preparation of the culture broth in step B) comprises keeping certain parameters within pre-determined value ranges, in particular:

[0109] - a pH of 3.0-6.5, preferably 3.0-4.3, and more preferably at approximately 3.5;

[0110] - the concentration of the dissolved solids measured in degrees Brix is 8-25, preferably 13-20, and still more preferably approximately 15;

[0111] - the temperature is 20-45 °C, preferably 24-28 °C, and still more preferably approximately 27 °C;

[0112] - the concentration of the dissolved oxygen is 8-40 mg / L, preferably 12-20 mg / L, and still more preferably approximately 16 mg / L.

[0113] In step d) the fermentation broth is inoculated with at least one microorganism, which constitutes what is known as the "fermentation starter". Preferably, said microorganism in the first mother culture is Komagataeibacter xylinus; preferably, said microorganism in the second mother culture is Streptococcus thermophilus, or Lactobacillus debruecki bulgaricus.

[0114] The amount of the microorganism inoculated is 102-109CFU / ml, preferably 104-107CFU / ml, and still more preferably in the range of 104CFU / ml, with an inoculant dose of 0.1-20 wt%, preferably of 0.2%-5 wt%, and still more preferably of 0.3-1 wt%.

[0115] Fermentation step D) is preferably performed in the following conditions:

[0116] - at a pH of 2.5-6.0, more preferably of 2.5-3.8, and still more preferably of approximately 3.0; - at a temperature of 10-32 °C, more preferably of 18-30 °C, and still more preferably of approximately 28 °C;

[0117] - the concentration of dissolved oxygen is 8-40 mg / L, more preferably 12-20 mg / L, and stillmore preferably approximately 16 mg / L;

[0118] In preferred embodiments, fermentation step D) is performed:

[0119] - for a time of 5-240 hours, more preferably 5-160 hours, and still more preferably 7-20 hours; and

[0120] - until a bacterial load of 103- 107CFU / ml is reached, more preferably of 104- 106CFU / ml, and still more preferably in the range of 105CFU / ml.

[0121] It is appreciable and advantageous that the fermented culture broth obtainable at the end of step D) can be utilized as a fermentation starter in bread-based products.

[0122] It is furthermore appreciable and advantageous that the inactive fermented culture broth obtainable at the end of step E) can be utilized in prebiotic products to provide reinforced prebiotic products.

[0123] In a further aspect, the present invention concerns a phytocomplex obtainable by the process described above, for use as a bowel regulator.

[0124] In a further aspect, the present invention concerns a phytocomplex obtainable by the process described above, for topical use as a healing agent.

[0125] In a still further aspect, the present invention concerns the use of the hydrolysate and of the products containing said hydrolysate, including gluten-free products, to reduce the glycaemic index, in particular in the treatment of subjects, including those with coeliac disease, suffering from diseases such as diabetes, metabolic syndrome, obesity, and cardiovascular diseases, in which the glycaemic index is above the normal range.

[0126] It should be understood that all the possible combinations of the preferred aspects of the procedure for the preparation of the hydrolysate stated above, and the uses and products thereof, and likewise the products containing said hydrolysate have been described and are likewise preferred.

[0127] It should furthermore be understood that all the aspects identified as preferred and advantageous for the hydrolysate and the components thereof are to be considered similarly preferred and advantageous also for the preparation and uses of said hydrolysate.

[0128] Below are working examples of the present invention provided for illustrative purposes.

[0129] EXAMPLES

[0130] Methods used:

[0131] - Determination of the arabinoxylans: phloroglucinol method (S. G. Douglas, ‘M rapid method for the determination of pentosans in wheat flour”, Food Chemistry, 7, 1981, 139-145) usingD-xylose at 510-552 nm as reference standard.

[0132] - Determination of the proteins: Dumas method, Nitrogen, Proteins from calculation o (> 0.05g / 100g) MI 2272 rev 04 2018 (accredited with a fixed scope of accreditation for at least 2 years)

[0133] - Determination of the gluten: “R5 Mendez ELISA” method, containing anti-RS antibody sandwich

[0134] Example 1. Process for the production of deproteinized hydrolysate from wheat bran 100.00 kg of micronized wheat bran were provided, comprising 16.20 kg of arabinoxylans and 17.58 kg of proteins.

[0135] The micronized bran was placed in a hydrolysis vat, to which water was added up to a weight ratio of 1:3, at a temperature of 50 °C.

[0136] KOH was added up to pH 11 and the resulting mixture was kept stirred for an hour.

[0137] Subsequently, the mixture was subjected to centrifugation in a horizontal axis centrifuge operating with a flow rate of 3 m3 / hour, with the drum rotation velocity set at approximately 4,200 revolutions per minute, i.e. 25% lower than the screw feeder rotation velocity, while the impeller eye diameter was set at 180 mm.

[0138] The liquid was disposed of, while the deproteinized bran was collected.

[0139] At the end of this first part of the process [steps i)-iv)], the removal of the majority of the proteins present in the micronized bran had been achieved without significantly impacting the arabinoxylan content, as can be seen from the following table:

[0140] micronized bran bran fraction

[0141] - step i) - after step iv)

[0142] Arabinoxylans 16.20 kg 14.90 kg (92 wt%)

[0143] Proteins 17.58 kg 3.16 kg (18 wt%)

[0144]

[0145] The thus deproteinized bran fraction was transferred back to the hydrolysis vat, to which water was added up to a weight ratio of 1:3 at a temperature of 50 °C.

[0146] An enzymatic complex consisting of endo-l,4-beta-xylanase + alpha-amylase + endo-l,3(4)-beta-glucanase at a concentration of 0.1 wt% and a pH of 5 was added to the mixture thus obtained and the temperature was brought to 60 °C for 4 hours.

[0147] The enzymatic complex was then deactivated, by heating to 85 °C for 15 minutes, while theresulting hydrolysate was separated by centrifugation in a horizontal axis centrifuge operating with a flow rate of 3 m3 / hour, with the drum rotation velocity set at approximately 4,200 revolutions per minute, i.e. 25% lower than the screw feeder rotation velocity, while the impeller eye diameter was set at 180 mm.

[0148] The hydrolysate was successfully concentrated by means of a falling film evaporator and subsequently desiccated by spray drying, obtaining 21 kg of powdered hydrolysate.

[0149] At the end of this second part of the process [steps v)-xi)], the final hydrolysate demonstrated further protein removal while also preserving a significant amount of arabinoxylans, as can be seen from the following table:

[0150] micronized bran bran fraction desiccated hydrolysate - step i) - after step iv) - after step xi) Arabinoxylans 16.20 kg 14.92 kg 4.75 kg

[0151] (92.01 wt%) (29.32 wt%)

[0152] Proteins 17.58 kg 3.16 kg 1.25 kg

[0153] (17.97 wt%) (7.11 wt%)

[0154] Gluten 1800 ppm

[0155]

[0156] Example 2. Process for the production of deproteinized / deglutinated hydrolysate from wheat bran

[0157] With reference to Example 1, the same procedure was performed as regards steps i)-ix) and xi), while step x) was performed by concentrating the hydrolysate by means of a stirred film evaporator, adding 0.03 wt% of proline-specific endopeptidase.

[0158] Downstream of the desiccation by means of spray drying, 20 kg of powered hydrolysate was obtained.

[0159] The final hydrolysate demonstrated further protein removal, in addition to gluten removal, while also preserving a significant amount of arabinoxylans, as can be seen from the following table:

[0160] micronized bran bran fraction desiccated - step i) - after step iv) hydrolysate

[0161] - after step xi) Arabinoxylans 16.20 kg 14.92 kg 4.65 kg

[0162] (92.01 wt%) (28.70 wt%)

[0163]

[0164] Proteins 17.58 kg 3.16 kg 0.95 kg

[0165] (17.97 wt% ) (5.40 wt%)

[0166] Gluten < 20 ppm

[0167]

[0168] Example 3.

[0169] Preparation of a phytocomplex

[0170] - Preparation of the starter

[0171] Prepare 350 ml of the hydrolysate aqueous solution from Example 1, 15 °Brix at pH 4, achieving microbiological and enzymatic stabilization with gentle stirring for 2 hours.

[0172] Inoculate with Komagataeibacter xylinus cells.

[0173] Incubate at a temperature of 28 °C in controlled aerobic conditions for 150 hours until reaching 7 °Brix, pH 3.9, with continuous observation of optical density. Evaluation of the kinetics and the organic acid concentrations.

[0174] - Preparation of the fermentation broth

[0175] Prepare 70 L of apple preparation, at 15 °Brix, pH 3.5, achieving microbiological and enzymatic stabilization with gentle stirring for 2 hours.

[0176] - Inoculation with the starter

[0177] Inoculate with the starter at a temperature of 28 °C in controlled aerobic conditions for 140 hours until reaching 7 °Brix, pH 3, with continuous observation of optical density. Evaluation of the kinetics and the organic acid concentrations; expected cell concentration >104Lowering of temperature to T=12-14 °C with gentle stirring and controlled decrease.

[0178] Unloading and packing.

Claims

CLAIMS1. Process for the industrial preparation of a hydrolysate from cereals, having a reduced protein content and enriched in arabinoxylans, said process comprising the steps of:i) providing a micronized cereal fraction (< 300 microns) and transferring the same to a reactor equipped with a stirrer,ii) adding water having a temperature of 40-60°C, and mixing until a first homogeneous mixture is obtained,iii) adjusting the pH to 9-11 and maintaining under stirring for about one hour, iv) separating the water in which proteins are dissolved, by means of a horizontal axis centrifuge with an adjustable impeller, from the cereal fraction thus deproteinized, v) transferring the deproteinized cereal fraction back to the reactor equipped with a stirrer,vi) adding water up to a weight ratio of 1:1 to 1:5 (deproteinized cereal fraction: water) thus obtaining a second homogeneous mixture,vii) adding to the mixture thus obtained up to 2wt%, based on the weight of the second mixture, of an enzymatic complex consisting of:a) xylanase, orb) xylanase, amylase and glucanase,and leaving to react for at least 6 hours at a temperature of 45 -65 °C and a pH of 3-6, viii) deactivating the enzymatic complex of step vii), by increasing the temperature to 80-90°C for at least 5 minutes,ix) separating the liquid component from the solid component obtained at the end of step viii ), by means of a horizontal-axis centrifuge with an adjustable impeller, while retaining the liquid component, i.e. the hydrolysate from the cereal fraction thus further deproteinized,x) concentrating the hydrolysate by means of:a) a stirred film evaporator, adding up to 0.05wt% of proline-specific endopeptidase, thereby obtaining a concentrated hydrolysate having a dry matter residue of 15-25 brix, containing < 20 ppm gluten,orb) a falling film evaporator, thereby obtaining a concentrated hydrolysate havinga dry matter residue of 25-35° brix, containing 1000-2500 ppm gluten, andxi) drying the concentrated hydrolysate thus obtaining a powdered hydrolysate comprising 15-40wt% of arabinoxylans and 5-9wt% of proteins.

2. The process of claim 1, wherein, in step iv), the horizontal -axis centrifuge operates at a flow rate of 2.5-3.5 m’ / hour, the rotation speed of the drum is 20-30% lower than the rotation speed of the screw conveyor, and the impeller eye is set at 150-200 mm in diameter.

3. The process of claim 1 or 2, wherein, in step ix), the horizontal-axis centrifuge operates at a flow rate of 2.5-3.5 m3 / hour, the rotation speed of the drum is 20-30% lower than the rotation speed of the screw conveyor, and the impeller eye is set at 150-200 mm in diameter.

4. The process of any one of claims 1-3, wherein the dried hydrolysate obtained from step xi) comprises 20-30wt% of arabinoxylans and 5-7wt% of proteins.

5. A cereal hydrolysate obtainable by the process of claim 1, said hydrolysate being soluble in water and comprising 15-40wt% of arabinoxylans, 5-9wt% of proteins and < 20 ppm of gluten, the hydrolysate being obtained by carrying out variant a) of step x) of the process.

6. A cereal hydrolysate obtainable by the process of claim 1, said hydrolysate being soluble in water and comprising 15-40wt% of arabinoxylans, 5-9wt% of proteins and 1000-2500 ppm of gluten, the hydrolysate being obtained by cartying out variant b) of step x) of the process.

7. The hydrolysate of claim 5 or 6, comprising 20-30wt% of arabinoxylans, and 5-7wt% of proteins.

8. Food composition, food supplement or food product, comprising the hydrolysate of any one of claims 5-7.

9. The food product of claim 8, said food product being an edible product selected from baked goods, feed, alcoholic beverages, soft drinks, energy drinks, diet bars, edible oils, so-called"breakfast cereals", fresh pasta, dry pasta, yogurt, ice cream, fruit juices and sweets, such as sugar and chocolate.

10. Use of the hydrolysate of any one of claims 5-7, or of food products containing the same, also gluten-free, for the reduction of the glycaemic index, in particular in the treatment of subjects, including celiacs, affected by pathologies, such as diabetes, metabolic syndrome, obesity, cardiovascular diseases, in which the glycaemic index is higher than normal values.RIASSUNTOÈ descritto un procedimento per produrre industrialmente un idrolizzato di cereale deproteinato (deglutinato), in particolare da frazioni micronizzate di cereali, nonche i suoi usi nell’alimentazione umana ed animale. Tale procedimento consente di ottenere un idrolizzato solubile in acqua e contenente una percentuale elevata di pentosani a basso peso molecolare che offre pertanto un elevata biodisponibilita di fibre solubili, al tempo stesso avendo un ridotto apporto proteico, in particolare di glutine. Ciò consente di superare gli svantaggi associati ad un elevate consumo di prodotti integrali, al tempo stesso beneficiando dei componenti nutritivi in essi contenuti.

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