WO2019022821A1

WO2019022821A1 - Water-soluble polysaccharides of improved palatability

Info

Publication number: WO2019022821A1
Application number: PCT/US2018/033817
Authority: WO
Inventors: Oliver Petermann
Original assignee: Dow Global Technologies LLC
Current assignee: Dow Global Technologies LLC
Priority date: 2017-07-26
Filing date: 2018-05-22
Publication date: 2019-01-31
Anticipated expiration: 2020-01-26

Abstract

A stable hydrogel is formed from a methylcellulose (A) and water by heat treatment and syneresis. The hydrogel, at a temperature of 21 C, has a water content of from 15 to 95.0 weight percent, based on the total weight of the hydrogel. It additionally comprises a non-starch water-soluble polysaccharide (B) which is different from the methylcellulose (A). The methylcellulose (A) has a high viscosity and anhydroglucose units joined by 1-4 linkages wherein hydroxy groups of anhydroglucose units are substituted with methyl groups such that s23/s26 is 0.36 or less, wherein s23 is the molar fraction of anhydroglucose units wherein only the two hydroxy groups in the 2- and 3-positions of the anhydroglucose unit are substituted with methyl groups and s26 is the molar fraction of anhydroglucose units wherein only the two hydroxy groups in the 2- and 6-positions of the anhydroglucose unit are substituted with methyl groups.

Description

WATER-SOLUBLE POLYSACCHARIDES OF IMPROVED PALAT ABILITY

FIELD

This invention concerns water-soluble polysaccharides of improved palatability and a method of preparing them.

INTRODUCTION

Water-soluble polysaccharides have found a wide range of uses in food, food ingredients or food supplements.

One end-use is known as "dietary fiber". This term is often used to describe non- starch water-soluble polysaccharides which are not digested by enzymes of the upper intestinal tract. Dietary fibers can be used as slimming aid for obese and non-obese individuals and/or as a bulk laxative. Some dietary fibers, such as guar gum,

methylcellulose or hydroxypropyl methylcellulose, form viscous solutions in water and have been shown to be efficient at inducing satiety and/or at reducing caloric intake or causing weight loss in individuals.

International Patent Application WO 2005/020718 discloses the use of a large number of biopolymers for inducing satiety in a human or animal, such as non-starch

polysaccharides selected from alginates, pectins, carrageenans, amidated pectins, xanthans, gellans, furcellarans, karaya gum, rhamsan, welan, gum ghatti, and gum arabic. Of these, alginates are said to be especially preferred. Alternatively, neutral non-starch

polysaccharides selected from galactamannan, guar gum, locust bean gum, tara gum, ispaghula, P-glucans, konjacglucomannan, methylcellulose, gum tragacanth, detarium, or tamarind may be used.

International Patent Application WO 92/09212 discusses that one major disadvantage in the use of these types of polysaccharides is the difficulty in controlling their swelling behavior. The dry dietary fiber is usually dispersed in an aqueous medium, thus giving rise to a very rapid swelling through the binding of water molecules to the polysaccharide, i.e., the dissolution of the fiber takes place more or less instantaneously. The highly viscous dispersion which is then formed becomes difficult to ingest if not taken immediately and provides a slimy or tacky sensation in the mouth. To overcome this problem WO 92/09212 suggests a dietary fiber composition comprising a water-soluble, nonionic cellulose ether having a cloud point not higher than 35 °C, such as ethyl hydroxyethyl cellulose and a charged surfactant, such as alkyl ammonium compounds or alkyl ether sulphates, such as sodium dodecyl sulphate (SDS). SDS is used in large quantities in detergent compositions, but animal studies have suggested that SDS causes skin and eye irritation.

Grades of methylcellulose that gel in water and form quite strong gels at body temperature are disclosed in International Patent Applications WO2011/139763 and

WO2014/168915. These grades of methylcellulose are consumed as cold solutions in water, i.e., having room temperature or lower. Upon ingestion the aqueous solutions of methylcellulose warm up to body temperature and form a gel mass in the individual's body, which induces satiety. Unfortunately, the cold solutions in water of these grades of methylcellulose also tend to provide a slimy or tacky sensation and a bad taste in the mouth when they are ingested.

WO2014/168914 seeks to improve the palatability of non- starch water-soluble polysaccharides by coating them with a methylcellulose which is different from the polysaccharide and which has anhydroglucose units joined by 1-4 linkages wherein hydroxy groups of anhydroglucose units are substituted with methyl groups such that s23/s26 is 0.36 or less, wherein s23 is the molar fraction of anhydroglucose units wherein only the two hydroxy groups in the 2- and 3-positions of the anhydroglucose unit are substituted with methyl groups and wherein s26 is the molar fraction of anhydroglucose units wherein only the two hydroxy groups in the 2- and 6-positions of the anhydroglucose unit are substituted with methyl groups. When the coated polysaccharides, such as coated hydroxypropyl methylcellulose (HPMC) is dispersed in water, the viscosity increase of the aqueous HPMC solution is delayed, as compared to the viscosity increase when a corresponding non-coated HPMC is dispersed in water. However, these coated water-soluble polysaccharides require rapid consumption after they have been added to water. Moreover, the coating process adds high costs to the water-soluble polysaccharides.

U.S. Patent No. 5,281,584 discloses that high viscosity cellulose ethers are effective for reducing serum cholesterol levels in humans. They are incorporated in bakable food compositions, such as cookies at an amount of 2 - 25 wt.%. The remaining part of the composition is composed of food ingredients, mainly butter, sugar, and flour, such as wheat flour. Unfortunately, the high viscosity cellulose ethers contribute to a grainy or gritty mouth feel. U.S. Patent No. 5,281,584 teaches that the palatability of the bakable food compositions can be improved by selecting a high viscosity cellulose ether of a certain particle size distribution. However, the consumption of the high viscosity cellulose ether in the form of cookies goes hand in hand with the consumption of calories inherent to the above-mentioned food ingredients. This is undesirable for managing the weight, reducing caloric intake or causing weight loss in individuals.

Accordingly, it would be desirable to find another way to improve the palatability of non-starch water-soluble polysaccharides. It would be particularly desirable to improve the palatability of non-starch water-soluble polysaccharides without making use of a charged monomeric surfactant.

SUMMARY

Surprisingly, it has been found that such non-starch water-soluble polysaccharides, such as cellulose ethers, can be administered as chewable gels, also designated as gummies or pastilles, even when these water-soluble polysaccharides do not form thermostable gels. The new form of administering non-starch water-soluble polysaccharides does not lead to the gritty or sandy mouthfeel and/or to the additional caloric intake which is experienced when consuming cookies comprising such non-starch water-soluble polysaccharides.

Moreover, the new form of administering non-starch water-soluble polysaccharides does not provide the bad taste in the mouth which is experienced when consuming a liquid aqueous solution comprising such non-starch water-soluble polysaccharides.

Surprisingly, a process has been found that allows the production of gelatin-free hydrogels or gummies or pastilles that do not melt back to aqueous solutions at room temperature (21 °C) or refrigerator temperature (4 °C) and that comprise non-starch water- soluble polysaccharides, such as cellulose ethers.

In preferred embodiments the process even allows the production of gelatin- free hydrogels or gummies or pastilles that comprise non-starch water-soluble polysaccharides, such as cellulose ethers, which even maintain a substantially stable shape at room temperature or even at refrigerator temperature (4 °C).

Accordingly, one aspect of the present invention is hydrogel which is formed from a methylcellulose (A) and water by heat treatment and syneresis and which additionally comprises a non-starch water-soluble polysaccharide (B) which is different from the methylcellulose (A), wherein the hydrogel, at a temperature of 21 °C, has a water content of from 15 to 95.0 weight percent, based on the total weight of the hydrogel, and

the methylcellulose (A) has a viscosity of at least 1,000 mPa»s, when measured as a 2 wt. % solution in water at 5 °C at a shear rate of 10 s ¹, and anhydroglucose units joined by 1-4 linkages wherein hydroxy groups of anhydroglucose units are substituted with methyl groups such that s23/s26 is 0.36 or less, wherein s23 is the molar fraction of anhydroglucose units wherein only the two hydroxy groups in the 2- and 3-positions of the anhydroglucose unit are substituted with methyl groups and s26 is the molar fraction of anhydroglucose units wherein only the two hydroxy groups in the 2- and 6-positions of the anhydroglucose unit are substituted with methyl groups.

Another aspect of the present invention is a process for producing a hydrogel from a methylcellulose (A) and water and additionally incorporating a non-starch water-soluble polysaccharide (B) being different from the methylcellulose (A) in the hydrogel, wherein the process comprises the steps of

a) preparing an aqueous solution comprising at least 1.9 wt.-% of an above-mentioned methylcellulose (A), based on the total weight of the aqueous solution, and comprising a non-starch water-soluble polysaccharide (B),

b) heating the aqueous solution of step a) to form a hydrogel from the aqueous solution,

c) maintaining the formed hydrogel at least at a temperature at which the hydrogel has been formed in step b) for a sufficient time period to liberate at least 15 weight percent of water from the hydrogel, based on the water weight in the aqueous solution in step a), provided that the remaining water content in the formed hydrogel is from 15 to 95.0 weight percent, based on the total weight of the hydrogel, and

d) separating liberated water from the hydrogel and cooling the hydrogel to a temperature of 25 °C or less simultaneously or in any sequence.

DESCRIPTION OF EMBODIMENTS

According to the general understanding in the art "gel" refers to a soft, solid, or solidlike material which comprises at least two components, one of which is a liquid present in abundance (Almdal, Dyre, J., Hvidt, S., Kramer, O.; Towards a phenomological definition of the term 'gel'. Polymer and Gel Networks 1993, I, 5-17). A hydrogel is a gel wherein water is the main liquid component.

The methylcellulose (A) used for preparing the hydrogel of the present invention has anhydroglucose units joined by 1-4 linkages. Each anhydroglucose unit contains hydroxyl groups at the 2, 3, and 6 positions. Partial or complete reaction of these hydroxyls creates cellulose derivatives. For example, treatment of cellulosic fibers with caustic solution, followed by a methylating agent, yields cellulose ethers substituted with one or more methyl groups. If the hydroxyl groups are not substituted with other groups than methyl groups, this cellulose derivative is known as methylcellulose.

An essential feature of the present invention is the use of a specific methylcellulose (A) wherein hydroxy groups of anhydroglucose units are substituted with methyl groups such that s23/s26 is 0.36 or less, preferably 0.33 or less, more preferably 0.30 or less, most preferably 0.27 or less, or 0.26 or less, and particularly 0.24 or less or 0.22 or less. Typically s23/s26 is 0.08 or more, 0.10 or more, 0.12 or more, 0.14 or more, or 0.16 or more.

In the ratio s23/s26, s23 is the molar fraction of anhydroglucose units wherein only the two hydroxy groups in the 2- and 3-positions of the anhydroglucose unit are substituted with methyl groups and s26 is the molar fraction of anhydroglucose units wherein only the two hydroxy groups in the 2- and 6-positions of the anhydroglucose unit are substituted with methyl groups. For determining the s23, the term "the molar fraction of

anhydroglucose units wherein only the two hydroxy groups in the 2- and 3-positions of the anhydroglucose unit are substituted with methyl groups" means that the two hydroxy groups in the 2- and 3-positions are substituted with methyl groups and the 6-positions are unsubstituted hydroxy groups. For determining the s26, the term "the molar fraction of anhydroglucose units wherein only the two hydroxy groups in the 2- and 6-positions of the anhydroglucose unit are substituted with methyl groups" means that the two hydroxy groups in the 2- and 6-positions are substituted with methyl groups and the 3-positions are unsubstituted hydroxy groups. The term "OH groups substituted with methyl groups" as used herein means that OH groups have been reacted to OCH3 groups.

Formula I below illustrates the numbering of the hydroxy groups in anhydroglucose units.

Formula I Methylcellulose can be characterized by the weight percent of methoxyl groups. By convention, the weight percent is an average weight percentage based on the total weight of the cellulose repeat unit, including all substituents. The content of the methoxyl group is reported based on the mass of the methoxyl group (i.e.,— OCH3). The determination of the % methoxyl in methylcellulose (MC) polymer is carried out according to the United States Pharmacopeia (USP 37, "Methylcellulose", pages 3776-3778). The % methoxyl can be converted into degree of substitution (DS) for methyl substituents, DS(methyl). DS(methyl), also designated as DS(methoxyl), of a methylcellulose is the average number of OH groups substituted with methyl groups per anhydroglucose unit. Preferably, the methylcellulose (A) has % methoxyl of 18% or more; more preferably 25% or more. Preferably, the

methylcellulose (A) has % methoxyl of 40% or less; more preferably 35% or less. Even more preferably, the methylcellulose (A) has a DS(methyl) of 1.55 or higher; more preferably 1.65 or higher; and most preferably 1.70 or higher. DS(methyl) is preferably 2.25 or lower; more preferably 2.20 or lower; and most preferably 2.10 or lower.

The viscosity of the methylcellulose (A) that is used in the process and the hydrogel of the present invention is important. The viscosities of standard grades of methylcellulose that gel at around 50 to 60 °C is typically measured as a 2 wt.-% solution in water at 20 °C. However, the methylcellulose (A) that is utilized in the present invention gels at lower temperature. Therefore, the viscosity of the methylcellulose (A) that is used in the process and the hydrogel of the present invention is measured as a 2 wt.-% solution in water at 5 °C at a shear rate of 10 s ¹ to obtain accurate results. The methylcellulose (A) utilized in the present invention has a viscosity of at least 1000 mPa»s, preferably at least 2000 mPa»s, more preferably at least 5000 mPa»s, and most preferably at least 10,000 mPa»s. Generally, the methylcellulose (A) has a viscosity of up to 100,000 mPa»s. Preferably, the

methylcellulose has a viscosity of up to 80,000 mPa»s, more preferably up to 60,000 mPa»s, and most preferably up to 40,000 mPa»s. All these viscosities are measured as a 2 wt.-% solution in water at 5 °C at a shear rate of 10 s ¹.

Processes for producing the methylcellulose (A) utilized in the process and in the hydrogel of the present invention are described in International Patent Application WO 2014/168915 Al, pages 13 - 16, the teaching of which is incorporated herein by reference.

In step a) of the process of the present invention an aqueous solution comprising at least 1.9 wt.-% of the above-described methylcellulose (A) is prepared, based on the total weight of the aqueous solution. Preferably an aqueous solution comprising at least 2.0 wt.-%, more preferably at least 2.5 wt.-%, even more preferably at least 2.8 wt.-%, and most preferably at least 3.0 wt.-% methylcellulose (A) is prepared. Typically an aqueous solution comprising up to 20 wt.-%, more typically up to 15 wt.-%, even more typically up to 10 or 8 wt.-%, and most typically up to 6 wt.-% of the above-described methylcellulose (A) is prepared, based on the total weight of the aqueous solution.

The preferred concentration of methylcellulose (A) in the aqueous solution that is produced in step a) of the process of the present invention is dependent on the viscosity and the s23/s26 ratio of the methylcellulose. When the methylcellulose (A) has a viscosity of at least 10,000 mPa»s, measured as a 2 wt.-% solution in water, an aqueous solution is prepared that generally comprises from 1.9 to 7 wt.-%, typically from 2.5 to 6.5 wt.-%, more typically from 3.0 to 6 wt.-% methylcellulose (A). When the methylcellulose (A) has a viscosity of less than 10,000 mPa»s, measured as a 2 wt.-% solution in water, it may be useful to prepare an aqueous solution that comprises from 5 to 20 wt.-%, typically from 6 to 15 wt.-% methylcellulose (A).

When a methylcellulose (A) is used wherein hydroxy groups of anhydro glucose units are substituted with methyl groups such that s23/s26 is 0.27 or less, or 0.26 or less, and particularly 0.24 or less or 0.22 or less, generally an aqueous solution is prepared that comprises from 1.9 to 10 wt.-%, preferably from 2.5 to 6.0 wt.-% methylcellulose (A). When such methylcellulose (A) also has a viscosity of at least 10,000 mPa»s, measured as a 2 wt.-% solution in water, typically a solution is prepared that comprises from 1.9 to 6.0 wt.-%, preferably 2.5 to 4.5 wt.-% methylcellulose (A).

When a methylcellulose (A) is used wherein hydroxy groups of anhydroglucose units are substituted with methyl groups such that s23/s26 is more than 0.27 and up to 0.36, generally an aqueous solution is prepared that comprises from 2.5 to 20 wt.-%, preferably from 3.0 to 15 wt.-% methylcellulose (A). When such methylcellulose (A) also has a viscosity of at least 10,000 mPa»s, measured as a 2 wt.-% solution in water, typically a solution is prepared that comprises from 2.5 to 7.0, preferably from 3.0 to 5.0 wt.-% methylcellulose (A).

In step a) of the process, wherein an aqueous solution of methylcellulose (A) is prepared, the above described methylcellulose (A) is typically utilized in ground and dried form. When a methylcellulose (A) is used wherein hydroxy groups of anhydroglucose units are substituted with methyl groups such that s23/s26 is 0.27 or less, the methylcellulose (A) is generally mixed with water while cooling the aqueous mixture to a temperature of not higher than 10 °C, preferably not higher than 8 °C, more preferably not higher than 6.5 °C, even more preferably not higher than 5 °C, and particularly from 0.5 to 2 °C. When a methylcellulose (A) is used wherein hydroxy groups of anhydroglucose units are substituted with methyl groups such that s23/s26 is more than 0.27 and up to 0.36, the methylcellulose (A) is generally mixed with water at a temperature of from 5 to 25 °C, preferably from 11 to 23 °C, and more preferably from 13 to 21 °C.

The non-starch water-soluble polysaccharides (B) which are useful in the process and the hydrogel of the present invention are different from the methylcellulose (A) have a solubility of at least 1 gram, more preferably at least 2 grams in distilled water at 25 °C and 1 atmosphere.

Examples of non-starch polysaccharides include natural gums comprising a polysaccharide hydrocolloid containing mannose repeating units, carrageenans, pectins, amidated pectins, xanthan gum, gum karaya, gum tragacanth, alginates, gellan gum, guar derivatives, xanthan derivatives, furcellarans, rhamsan, cellulose derivatives, or mixture of two or more of such polysaccharides.

Hydrocolloids are well known to the person skilled in the art and polysaccharide hydrocolloids are polysaccharide-based compositions that form colloidal dispersions (also referred to as "colloidal solutions") in water. In preferred embodiments the polysaccharide hydrocolloid is selected from glucomannan, galactomannan, and mixtures thereof.

Typically, the natural gum is a vegetable gum such as konjac gum, fenugreek gum, guar gum, tara gum, locust bean gum (carob gum), or a mixture of at least two of them.

Carrageenans are polysaccharides made of repeating units of galactose and 3,6- anhydrogalactose (3, 6- AG), both sulfated and nonsulfated. The units are joined by alternating la→3 and 1β→4 glycosidic linkages.

Guar derivatives and xanthan derivatives are described in more detail in European patent EP 0 504 870 B, page 3, lines 25-56 and page 4, lines 1-30. Useful guar derivatives are, for example, carboxymethyl guar, hydroxypropyl guar, carboxymethyl hydroxypropyl guar or cationized guar. Preferred hydroxypropyl guars and the production thereof are described in U.S patent No. 4,645,812, columns 4-6.

Preferred non-starch water-soluble polysaccharides (B) are water-soluble cellulose ethers, more preferably alkyl celluloses, hydroxyalkyl celluloses or hydroxyalkyl alkylcelluloses, such as C2-C3-alkyl celluloses, Ci-C3-alkyl hydroxy-Ci-3-alkyl celluloses, hydroxy-Ci-3-alkyl celluloses, mixed hydroxy-Ci-C3-alkyl celluloses, or mixed Ci-C3-alkyl celluloses, provided that the cellulose ether is different from the methylcellulose (A) described further above. Advantageously, the non-starch polysaccharide (B) is not methylcellulose. Typically one or two kinds of hydroxyalkoxyl groups are present in the cellulose ether. Preferably a single kind of hydroxyalkoxyl group, more preferably hydroxypropoxyl, is present.

Preferred alkyl hydroxyalkyl celluloses including mixed alkyl hydroxyalkyl celluloses are hydroxyalkyl methylcelluloses, such as hydroxyethyl methylcelluloses, hydroxypropyl methylcelluloses or hydroxybutyl methylcelluloses; or hydroxyalkyl ethyl celluloses, such as hydroxypropyl ethylcelluloses, ethyl hydroxyethyl celluloses, ethyl hydroxypropyl celluloses or ethyl hydroxybutyl celluloses; or ethyl hydroxypropyl methylcelluloses, ethyl hydroxyethyl methylcelluloses, hydroxyethyl hydroxypropyl methylcelluloses or alkoxy hydroxyethyl hydroxypropyl celluloses, the alkoxy group being straight-chain or branched and containing 2 to 8 carbon atoms. Preferred hydroxyalkyl celluloses are hydroxyethyl celluloses, hydroxypropyl celluloses or hydroxybutyl celluloses; or mixed hydroxylkyl celluloses, such as hydroxyethyl hydroxypropyl celluloses.

Preferred are hydroxyalkyl alkylcelluloses, more preferred are hydroxyalkyl methylcelluloses and most preferred are hydroxypropyl methylcelluloses, preferably those which have an MS(hydroxyalkoxyl) and a DS(alkoxyl) described below. The degree of the substitution of hydroxyl groups of the anhydroglucose units by hydroxyalkoxyl groups is expressed by the molar substitution of hydroxyalkoxyl groups, the MS (hydroxyalkoxyl). The MS (hydroxyalkoxyl) is the average number of moles of hydroxyalkoxyl groups per anhydroglucose unit in the cellulose ether. It is to be understood that during the

hydroxyalkylation reaction the hydroxyl group of a hydroxyalkoxyl group bound to the cellulose backbone can be further etherified by an alkylation agent, e.g. a methylation agent, and/or a hydroxyalkylation agent. Multiple subsequent hydroxyalkylation etherification reactions with respect to the same carbon atom position of an anhydroglucose unit yields a side chain, wherein multiple hydroxyalkoxyl groups are covalently bound to each other by ether bonds, each side chain as a whole forming a hydroxyalkoxyl substituent to the cellulose backbone. The term "hydroxyalkoxyl groups" thus has to be interpreted in the context of the MS(hydroxyalkoxyl) as referring to the hydroxyalkoxyl groups as the constituting units of hydroxyalkoxyl substituents, which either comprise a single hydroxyalkoxyl group or a side chain as outlined above, wherein two or more

hydroxyalkoxy units are covalently bound to each other by ether bonding. Within this definition it is not important whether the terminal hydroxyl group of a hydroxyalkoxyl substituent is further alkylated, e.g. methylated, or not; both alkylated and non-alkylated hydroxyalkoxyl substituents are included for the determination of MS (hydroxyalkoxyl). The hydroxyalkyl alkylcelluloses of the invention generally has a molar substitution of hydroxyalkoxyl groups in the range of 0.05 to 1.00, preferably 0.08 to 0.70, more preferably 0.10 to 0.50, even more preferably 0.10 to 0.40, and most preferably 0.10 to 0.35.

The average number of hydroxyl groups substituted by alkoxyl groups, such as methoxyl groups, per anhydroglucose unit, is designated as the degree of substitution of alkoxyl groups, DS(alkoxyl). In the above-given definition of DS, the term "hydroxyl groups substituted by alkoxyl groups" is to be construed within the present invention to include not only alkylated hydroxyl groups directly bound to the carbon atoms of the cellulose backbone, but also alkylated hydroxyl groups of hydroxyalkoxyl substituents bound to the cellulose backbone. The hydroxyalkyl alkylcelluloses according to this invention preferably have a DS(alkoxyl) in the range of 1.0 to 2.5, more preferably 1.1 to 2.2, and most preferably 1.25 to 2.10. Most preferably the cellulose ether is a hydroxypropyl methylcellulose or hydroxy ethyl methylcellulose having a DS (methoxyl) within the ranges indicated above for DS(alkoxyl) and an MS(hydroxypropoxyl) or an MS (hydroxy ethoxyl) within the ranges indicated above for MS (hydroxyalkoxyl). The degree of substitution of alkoxyl groups and the molar substitution of hydroxyalkoxyl groups can be determined by Zeisel cleavage of the cellulose ether with hydrogen iodide and subsequent quantitative gas chromatographic analysis (G. Bartelmus and R. Ketterer, Z. Anal. Chem., 286 (1977) 161- 190). When the hydroxyalkyl alkylcellulose is a hydroxypropyl methylcellulose (HPMC), the determination of the % methoxyl and % hydroxypropoxyl in HPMC is carried out according to the United States Pharmacopeia (USP 40). The values obtained are % methoxyl and % hydroxypropoxyl. These are subsequently converted into degree of substitution (DS) for methyl substituents and molar substitution (MS) for hydroxypropyl substituents.

The viscosity of the non-starch water-soluble polysaccharide (B), preferably a cellulose ether different from methylcellulose (A), more preferably a hydroxyalkyl alkylcellulose, and most preferably a hydroxypropyl methylcellulose, should generally be at least 600 mPa-s, typically at least 1000 mPa-s, preferably at least 10,000 mPa-s, more preferably from 25,000 to 2,000,000 mPa-s, even more preferably from 50,000 to 800,000 mPa-s, and most preferably from 100,000 to 500,000, determined as a 2.0 % by weight solution in water at 20°C ± 0.1 °C by a Brookfield viscosity measurement as described in the US Pharmacopeia (USP 40) on Hypromellose.

The polysaccharide (B) is generally incorporated in such amount in the aqueous solution in step a) that the weight ratio between the methylcellulose (A) and the

polysaccharide (B) is from 50 : 1 to 1 : 1, typically from 35 : 1 to 2 : 1, preferably from 25 : 1 to 4 : 1, more preferably from 20 : 1 to 6 : 1, even more preferably from 15 : 1 to 7 : 1, and most preferably from 12 : 1 to 8 : 1.

A low or high shear rate can be applied to prepare the aqueous solution in step a) for producing the hydrogel. In one embodiment of the invention the aqueous solution is prepared the aqueous solution is prepared at a shear rate of at least 1000 s ¹, as described in International Patent Application WO2014/168915.

Water or the aqueous solution of methylcellulose (A) and/or the polysaccharide (B) may be mixed with a minor amount of one or more organic liquids which are preferably physiologically acceptable, such as ethanol or one or more animal or vegetable oils, but the total amount of organic liquids is preferably not more than 10 percent, more preferably not more than 5 percent, even more preferably not more than 2 percent, based on the total weight of water and organic liquid. Most preferably, the aqueous liquid is not mixed with an organic liquid.

The aqueous solution prepared in step a) may comprise one or more active ingredients, such as fertilizers, herbicides or pesticides, or biologically active ingredients, such as vitamins, herbals and mineral supplements or drugs. The term "drug" is conventional, denoting a compound having beneficial prophylactic and/or therapeutic properties when administered to an animal, especially humans. The amount of the active ingredients generally is not more than 15 percent, preferably not more than 10 percent, more preferably not more than 5 percent, and most preferably not more than 2 percent, based on the total weight of the aqueous solution.

Other optional ingredients in the aqueous solution prepared in step a) are additives, such as coloring agents, pigments, opacifiers, flavoring agents, antioxidants, preservatives, salts, preferably inorganic salts, such as sodium chloride, potassium chloride, calcium chloride, or magnesium chloride; or combinations thereof. Examples of flavoring agents are sugars, artificial sweeteners, varying types of cocoa, pure vanilla or artificial flavor, such as vanillin, ethyl vanillin, chocolate, malt, and mint, extracts or spices, such as cinnamon, nutmeg and ginger; antioxidants, The amount of these additives is generally not more than 15 percent, preferably not more than 10 percent, more preferably not more than 5 percent, and most preferably not more than 2 percent, based on the total weight of the aqueous solution.

The optional ingredients are preferably pharmaceutically acceptable. The optional ingredients like active ingredients or additives may be added to the methylcellulose (A), to the polysaccharide (B), to water and/or to the aqueous solution before or during the process for producing the aqueous solution of methylcellulose (A) and polysaccharide (B) as described above. Alternatively, optional ingredients may be added after the preparation of the aqueous solution.

Generally the aqueous solution prepared in step a) of the present invention is gelatin- free. Other than the methylcellulose (A) and the polysaccharide (B) described above, the aqueous solution prepared in step a) of the present invention preferably does not comprise a significant amount of ingredients, such as thickeners or gelling agents, that are able to increase the gel strength of the produced hydrogel at room temperature (21 °C) or at a lower temperature. The polysaccharide (B), such as a water-soluble cellulose ether different from methylcellulose (A), preferably a hydroxypropyl methylcellulose, typically does not form a gel at room temperature or lower. Many of the above-mentioned polysaccharides (B) form gels at 50 - 60 °C or higher, depending on their concentration in water, but melt back to liquid aqueous solutions at room temperature.

The sum of the methylcellulose (A) and water is generally at least 70 percent, preferably at least 80 percent, more preferably at least 90 percent, and most preferably at least 95 percent, based on the total weight of the aqueous solution prepared in step a).

In step b) of the process of the present invention, the aqueous solution of step a) is heated to form a hydrogel from the aqueous solution. It is known that aqueous solutions of the methylcellulose (A) described in more details above can gel at a temperature as low as 31 °C. Increasing the concentration of the methylcellulose (A) or incorporating active ingredients or optional additives, such as tonicity-adjusting agents in the aqueous solution in step a) of the process of the present invention lowers the gelation temperature of the aqueous solution. For practical reasons the aqueous solution of step a) is generally heated to a temperature of at least 55 °C, preferably at least 65 °C, more preferably at least 70 °C, even more preferably at least 75 °C, and most preferably at least 80 °C to form a hydrogel from the aqueous solution. Generally the aqueous solution is heated to a temperature of up to 95 °C, typically up to 90 °C, and more typically up to 87 °C. In step c) of the process of the present invention, the formed hydrogel is maintained at least at a temperature at which the hydrogel has been formed in step b) for a sufficient time period to liberate at least 15 weight percent of water from the hydrogel, based on the weight of water in the aqueous solution in step a). Generally at least 20 wt.-%, preferably at least 25 wt.-%, more preferably at least 30 wt.-%, even more preferably at least 35 wt.-%, and most preferably even at least 40 weight percent of water is liberated from the hydrogel. In the most preferred embodiments of the process at least 45 wt.-% of water is liberated from the hydrogel. Generally up to 90 wt.-%, preferably up to 80 wt.-%, more preferably up to 75 wt.-%, even more preferably up to 70 wt.-%, and most preferably up to 65 wt.-% of water is liberated from the hydrogel, based on the weight of water in the aqueous solution in step a). In the most preferred embodiments of the process up to 60 wt.-% of water is liberated from the hydrogel.

In any event a sufficient amount of water is liberated from the hydrogel provided that the remaining water content in the hydrogel is from 15 to 95.0 weight percent, based on the total weight of the hydrogel. The remaining water content of the hydrogel is preferably up to 94.5 wt.-%, more preferably up to 94.0 wt.-%, and most preferably up to 93.5 weight percent, based on the total weight of the hydrogel. In some embodiments of the invention the remaining water content of the hydrogel is only up to 93.0 wt.-%, based on the total weight of the hydrogel. The remaining water content of the hydrogel is preferably at least 30 wt.-%, more preferably at least 50 wt.-%, and most preferably at least 70 weight percent, based on the total weight of the hydrogel. In some embodiments of the invention the remaining water content of the hydrogel is even at least 80 wt.-% or even at least 90 wt.-%, based on the total weight of the hydrogel.

For practical reasons the formed hydrogel is generally maintained at a temperature of at least 55 °C, preferably at least 65 °C, more preferably at least 70 °C, even more preferably at least 75 °C, and most preferably at least 80 °C. Generally the temperature in step c) is up to 95 °C, typically up to 90 °C, and more typically up to 87 °C. Generally maintaining the formed hydrogel at an above-mentioned temperature for at least 1 hour, preferably at least 1.5 hours, more preferably for at least 2 hours, and most preferably at least 3 hours is sufficient for expelling or liberating an amount of water as described above. During the heating of the hydrogel for an extended time period as described above, syneresis takes place and water is expelled or liberated from the hydrogel. Water is typically liberated from the hydrogel in its liquid state, however a portion of the expelled or liberated water can evaporate. In some embodiments of the invention even most or all of the expelled or liberated water can directly evaporate, e.g., by placing the formed hydrogel on a sieve or in or on another device that facilitates water evaporation. The preferred time periods to liberate an amount of water and to achieve a remaining water content as described above depends on the temperature and on the concentration of the methylcellulose (A) in the aqueous solution. The higher the chosen temperature and the concentration of the methylcellulose (A), the less time period is generally needed to expel the desired amount of water. Generally the formed hydrogel is maintained at an above-mentioned temperature for a time period of up to 12 hours, typically up to 10 hours, more typically up to 8 hours and in preferred embodiments up to 6 hours. Syneresis of hydrogels formed from methylcellulose (A) and water is known. However, it is important in the present invention to cause sufficient syneresis by heating to liberate an amount of as described above.

In step d) liberated water is separated from the hydrogel and the hydrogel is cooled to a temperature of 25 °C or less or to 23 °C or less or to 21 °C or less simultaneously or in any sequence. Typically the hydrogel is cooled to a temperature of 0 ° C or more, more typically of 4 ° C or more. Preferably liberated water is separated from the hydrogel before, while or shortly after the hydrogel is cooled to a temperature of 25 °C or less. However, it has surprisingly been found that the produced hydrogel can even be stored in expelled water at room temperature, e.g. at 20 - 25 °C, for an extended time period, such as up to 1 week or even up to 2 weeks without melting back of the hydrogel to an aqueous solution. Even storage in a refrigerator at 4 °C up to 5 days is possible. However, during storage for an extended time period some of the expelled water may diffuse back into the hydrogel, which may weaken the hydrogel. Therefore, it is preferred to separate liberated water from the hydrogel within 24 hours, preferably within 12 hours, and more preferably within 3 hours upon completion of step c).

Generally at least 80 percent, preferably at least more 85 percent, more preferably at least 90 percent, most preferably at least 95 percent, and particularly at least 98 percent of the liberated water is separated from the hydrogel, for example by draining or contacting the hydrogel with a cloth or another article that is able to remove liberated water from the hydrogel.

If desired, in step d) the hydrogel can even be cooled to a temperature of 0 °C or less, e.g., to a temperature of 0 °C to - 20 °C, more typically of 0 °C to - 10 °C. It is advisable to separate liberated water from the hydrogel before cooling the hydrogel to such a low temperature. For practical reasons the hydrogel is preferably cooled to a temperature of 23 °C to 4 °C.

Surprisingly, it has been found that the produced hydrogel does not display any melt back, remains a gel and keeps its shape even when it is stored for hours or days at a temperature of 25 °C or less, such as 23 °C to 4 °C.

Preferred embodiments of the produced hydrogel have a gel fracture force FG_F(21 °C) of at least 10 N, more preferably at least 12 N even more preferably at least 14 N and in the most preferred embodiments even at least 16 N. Typically the produced hydrogels have a gel fracture force FGF(21 °C) of up to 30 N, more typically up to 22 N. How to determine the gel fracture force FGF(21 °C) is described in the Examples section.

Another aspect of the present invention is a hydrogel that has been formed from a methylcellulose (A) and water by heat treatment and syneresis and that additionally comprises a non-starch water-soluble polysaccharide (B) being different from the methylcellulose (A), wherein the hydrogel, at a temperature of 21 °C, has a water content of from 15 to 95.0 weight percent, based on the total weight of the hydrogel. The

methylcellulose (A) and the non-starch water-soluble polysaccharide (B) in the hydrogel are as described in detail above. The water content of the hydrogel is preferably up to 94.5 wt.-%, more preferably up to 94.0 wt.-%, and most preferably up to 93.5 weight percent, based on the total weight of the hydrogel. In some embodiments of the invention the water content of the hydrogel is only up to 93.0 wt.-%, based on the total weight of the hydrogel. The water content of the hydrogel is preferably at least 30 wt.-%, more preferably at least 50 wt.-%, and most preferably at least 70 weight percent, based on the total weight of the hydrogel. In some embodiments of the invention the water content of the hydrogel is even at least 80 wt.-% or even at least 90 wt.-%, based on the total weight of the hydrogel.

The term "formed by heat treatment and syneresis" as used herein means that heat treatment is sufficient to liberate at least 15 weight percent of water from the hydrogel, based on the weight of water used to form the hydrogel. The term "formed by heat treatment and syneresis" preferably means that heat treatment is sufficient to liberate at least 20 wt.-%, preferably at least 25 wt.-%, more preferably at least 30 wt.-%, even more preferably at least 35 wt.-%, most preferably even at least 40 weight percent of water and in some embodiments even at least 45 wt.-% of water from the hydrogel, based on the weight of water used to form the hydrogel. In the hydrogel formed from the methylcellulose (A) and water by heat treatment and syneresis generally up to 90 wt.-%, preferably up to 80 wt.-%, more preferably up to 75 wt.-%, even more preferably up to 70 wt.-%, and most preferably up to 65 wt.-% and in some embodiments up to 60 wt.-% of water has been liberated from the hydrogel, based on the weight of water used to form the hydrogel. Ways to conduct the heat treatment are described further above.

Preferred embodiments of the methylcellulose (A) and the non-starch water-soluble polysaccharide (B) are described above. The hydrogel of the present invention preferably has a gel fracture force FGF(21 °C) of at least 10 N, more preferably at least 12 N, even more preferably at least 14 N and in the most preferred embodiments even at least 16 N.

Typically the hydrogel has a gel fracture force FGF(21 °C) of up to 30 N, more typically of up to 22 N. How to determine the gel fracture force FGF(21 °C) is described in the

Examples section.

The hydrogel of the present invention may comprise a minor amount of one or more organic liquids which are preferably physiologically acceptable, such as ethanol or one or more animal or vegetable oils, but the total amount of organic liquids is preferably not more than 10 percent, more preferably not more than 5 percent, even more preferably not more than 2 percent, based on the total weight of water and organic liquid in the hydrogel at a temperature of 21 °C. Most preferably, the hydrogel does not comprise an organic liquid.

The hydrogel of the present invention may comprise one or more active ingredients, such as fertilizers, herbicides or pesticides, or biologically active ingredients, such as vitamins, herbals and mineral supplements or drugs. The amount of the active ingredients generally is not more than 15 percent, preferably not more than 10 percent, more preferably not more than 5 percent, and most preferably not more than 2 percent, based on the total weight of the hydrogel at a temperature of 21 °C.

Other optional ingredients are additives, such as coloring agents, pigments, opacifiers, flavoring agents, antioxidants, preservatives, salts, such as sodium chloride, or combinations thereof. Examples of flavoring agents are sugars, artificial sweeteners, varying types of cocoa, pure vanilla or artificial flavor, such as vanillin, ethyl vanillin, chocolate, malt, and mint, extracts or spices, such as cinnamon, nutmeg and ginger; antioxidants, Optional ingredients are preferably pharmaceutically acceptable. The amount of these additives is generally not more than 15 percent, preferably not more than 10 percent, more preferably not more than 5 percent, and most preferably not more than 2 percent, based on the total weight of the hydrogel at a temperature of 21 °C. The hydrogel of the present invention is formed from a methylcellulose (A) and water. This means that no other gelling agents than the above described methylcellulose (A) are needed for gel formation at room temperature (21 °C) or lower. Generally the hydrogel of the present invention is gelatin-free. Other than the methylcellulose (A) and the

polysaccharide (B) described above, the hydrogel preferably does not comprise a significant amount of ingredients, such as thickeners or gelling agents that are able to increase the gel strength of the hydrogel at room temperature (21 °C) or at a lower temperature. The polysaccharide (B), such as a water-soluble cellulose ether different from methylcellulose (A), preferably a hydroxypropyl methylcellulose, typically does not form a gel at room temperature or lower. Many of the above-mentioned polysaccharides (B) form gels at 50 - 60 °C or higher, depending on their concentration in water, but melt back to liquid aqueous solutions at room temperature.

The sum of the methylcellulose (A) and water is generally at least 70 percent, preferably at least 80 percent, more preferably at least 90 percent, and most preferably at least 95 percent, based on the total weight of the hydrogel.

Some embodiments of the invention will now be described in detail in the following Examples.

EXAMPLES

Unless otherwise mentioned, all parts and percentages are by weight. In the

Examples the following test procedures are used.

Determination of % methoxyl in Methylcellulose (MC)

The determination of the % methoxyl in methylcellulose (MC) polymer is carried out according to the United States Pharmacopeia (USP 37, "Methylcellulose", pages 3776- 3778).

Determination of the viscosity of Methylcellulose

With the exception of Comparative Examples F - H, the steady-shear-flow viscosity η(5 °C, 10 s ¹, 2 wt.% MC) of an aqueous 2-wt.% methylcellulose solution is measured at 5 °C at a shear rate of 10 s ¹ with an Anton Paar Physica MCR 501 rheometer and cone- and-plate sample fixtures (CP-50/1, 50-mm diameters). Determination of s23/s26 of Methylcellulose

The approach to measure the ether substituents in methylcellulose is generally known. See for example the approach described in principle for Ethyl Hydroxyethyl Cellulose in Carbohydrate Research, 176 (1988) 137-144, Elsevier Science Publishers B.V., Amsterdam, DISTRIBUTION OF SUBSTITUENTS IN 0-ETHYL-0-(2-HYDROXYETHYL)

CELLULOSE by Bengt Lindberg, Ulf Lindquist, and Olle Stenberg.

Specifically, the determination of s23/s26 is conducted as described in International Patent Application No. WO 2014/168915 Al, pages 18 - 21, the teaching of which is incorporated herein by reference.

Hydroxypropyl methylcellulose (HPMC)

The non-starch water-soluble polysaccharide (B) is a hydroxypropyl methylcellulose (HPMC) which has a methoxyl content of 23 % and a hydroxypropoxyl content of 9 %, corresponding to a DS(methoxyl) of 1.45 and an MS (hydroxypropoxyl) of 0.24. The determination of the % methoxyl and % hydroxypropoxyl in HPMC is carried out according to the United States Pharmacopeia (USP 40). The values obtained are % methoxyl and % hydroxypropoxyl.

The HPMC has a viscosity of about 245,000 mPa»s, determined as a 2.0 % by weight solution in water at 20°C ± 0.1 °C by an Brookfield viscosity measurement, as described in the US Pharmacopeia (USP 40) on Hypromellose.

Determination of the gel fracture force G_F(21 °C) of the hydrogel

The gel fracture force G_F(21 °C) is measured with a Texture Analyzer (model TA.XTPlus; Stable Micro Systems, 5-Kg load cell) at 21°C. The gels are compressed between a steel plate (90mmxl00mmx9mm with a filter paper0110mm "2294" from Whatman and then a filter vlies 0110mm "0980/1" from Whatman on the top of the plate) and a Teflon cylinder (diameter: 50mm, height: 20mm) with the following parameters: speed until first sample contact: 1.5mm/sec, speed of compression: 1.00 mm sec, trigger force: 0.005N, maximum distance: 20 mm). The plate displacement [mm] and compression force [N] is measured at selected time intervals (400 points/s) until the gel collapses. The maximum compressional force is the maximum height of the peak during gel collapse. It is identified as _GF(21 °C). Reference Example I and Comparative Examples A and B (not Prior Art)

A methylcellulose (MC) is used that has a methoxyl content of 30.4 %, a viscosity of 8610 MPa»s, measured as a 2 wt. % solution in water at 5 °C at a shear rate of 10 s ¹, and a ratio s23/s26 of 0.23. This methylcellulose is designated as MC-I.

In each of the experiments 35.0 g of an aqueous solution of the MC-I is prepared in a glass container. The MC-I concentration, based on the total weight of the aqueous solution, is as listed in Table 1 below. The aqueous solutions are prepared by stirring at 1000 rpm in an ice bath for 6 hours and storage overnight in a refrigerator. Then the solutions are centrifuged (Sorvall Lynx 4000 centrifuge at 4000 rpm at 10°C) until the solutions are free of air bubbles.

The aqueous solutions are then heated to a temperature as listed in Table 1 below and kept at this temperature for a time period as listed in Table 1.

All aqueous solutions gel at the temperature to which they are heated (50 °C or 85 °C, respectively). During the heat treatments for the time periods listed in Table 1 below the hydrogels undergo syneresis to different degrees wherein the entire amount of methyl cellulose remains in the hydrogel and a portion of the water is expelled from the hydrogel. Water that is expelled during the heat treatment is separated from the hydrogels. The hydrogels are mechanically dried with a tissue and weighed while the gel is still hot. The % liberated water after the heat treatment is calculated according to the formula:

[1 - (g gel - g MC in aq. solution) / (g aqueous solution - g MC in aq. solution) ] x 100. The remaining water content of the produced hydrogel after heating is calculated from the weight of the hydrogel and the MC weight of the starting aqueous solution, which corresponds to the MC weight in the hydrogel.

The produced hydrogels are placed on a glass plate without delay and allowed to cool to room temperature. The texture of each hydrogel is assessed immediately after heat treatment, removal of expelled water and cooling to room temperature, but before storage in a refrigerator.

The produced hydrogels are then stored at 4 °C in a refrigerator for a time period as listed in Table 1 below. The hydrogel of Reference Example 1 remains a firm gel even after storage for an extended period of time in the refrigerator. No melt back occurs. The gels of Comparative Examples A and B have all melted after storage for 3 hours at 4 °C. Reference Examples II - X and Comparative Examples C - E (not Prior Art)

30.0 g of an MC-I solution is prepared in the same manner as in Reference Example I.

The MC-I concentration, based on the total weight of the aqueous solution, is as listed in

Tables 2 and 3 below.

The aqueous solutions are then heated to 85 °C and kept at 85 °C for a time period as listed in Tables 2 and 3 below.

All aqueous solutions gel at 85 °C. During the heat treatments most hydrogels undergo syneresis. The hydrogels are removed from the liberated water and dried with a tissue. The texture of each hydrogel is assessed immediately after heat treatment, removal of expelled water and cooling to room temperature, but before storage. The mass of each hydrogel after heat treatment as listed in Tables 2 and 3 below is determined by weighing as described above for Reference Example I. The % liberated water after the heat treatment and the remaining water content are calculated as described above for Reference Example I.

The produced hydrogels are then placed in separate bags and stored at 4 °C in a refrigerator for a time period as listed in Tables 2 and 3 below. The consistency of the hydrogels is assessed after the time periods listed in Tables 2 and 3 below.

The Reference Examples do not comprise a non-starch water-soluble polysaccharide (B). The Reference Examples are incorporated herein to illustrate that in steps b) and c) of the process of the present invention heating to a certain temperature during a certain time period is needed, as described in the general description, to be able to prepare a

thermostable hydrogel from the methylcellulose (A) and water that does not melt back when cooled to room temperature or even to 4 °C. Comparative Examples F - H

The experiments are carried out as described for Reference Examples III - V except that a different methylcellulose (MC) is used and the produced hydrogels are stored at room temperature for a time period as listed in Table 4 below. The MC has a methoxyl content of 29 %, a viscosity of 3290 MPa»s, measured as a 2 wt. % solution in water at 20 °C, and a ratio s23/s26 of 0.39. Such methylcelluloses are commercially available as Methocel A4M methylcellulose. The MC concentration is 3 wt.-%, based on the total weight of the aqueous solution.

The results of the assessments are listed in Table 4 below. The results show that all aqueous solutions gel at 85 °C. However, even during extended heat treatments the hydrogels do not undergo sufficient syneresis. Moreover, the hydrogels melt back upon storage at room temperature.

Reference Examples XI - XIII

The experiments are carried out as described for Reference Examples III - V, except that the produced hydrogels are stored at room temperature for a time period as listed in Table 4 below. Storage at room temperature allows a direct comparison with Comparative Examples F - H. The hydrogels of Reference Examples XI - XIII are solid dimensionally stable gel upon storage at room temperature for 1 day. After 2 days of storage at room temperature, they are still solid dimensionally stable gels.

The Reference Examples XI - XIII do not comprise a non-starch water-soluble polysaccharide (B). However, the Reference Examples XI - XIII and the Comparative Examples F - H illustrate that thermostable hydrogels can be prepared from the specific methylcelluloses (A) as claimed but not from any methylcelluloses like those utilized in Comparative Examples F - H.

Table 1

Table 2

Table 3

Table 4

Examples 1 and 2

The experiments are carried out as described for Reference Examples II - VIII, except that a blend of MC-I and HPMC at a weight ratio of 9 : 1 is dissolved in water. The MC-I and HPMC have the properties described further above. Aqueous solutions are prepared which have a total cellulose ether content of 3 wt.-% or 4 wt.-%, respectively. A 3 wt.-% aqueous solution contains 2.7 wt.-% MC-I and 0.3 wt.-% HPMC. A 4 wt.-% aqueous solution contains 3.6 wt.-% MC-I and 0.4 wt.-% HPMC. The results are listed in Table 5 below.

Table 5

Example 3

The experiment of Example 2 is repeated twice. A 4 wt.-% aqueous solution containing 3.6 wt.-% MC-I and 0.4 wt.-% HPMC is produced. Two samples of the aqueous solution (30 g each) are then heated to 85 °C and kept at 85 °C for 4 hours by placing glass containers holding the aqueous solution in a water bath.

The gel fracture forces GF(21 °C) of the produced hydrogels are determined after having stored the gels overnight at room temperature. The measured gel fracture forces G_F(21 °C) are 19.1 N and 19.3 N, respectively.

Claims

1. A hydrogel formed from a methylcellulose (A) and water by heat treatment and syneresis and additionally comprising a non-starch water-soluble polysaccharide (B) being different from the methylcellulose (A), wherein the hydrogel, at a temperature of 21 °C, has a water content of from 15 to 95.0 weight percent, based on the total weight of the hydrogel, and

the methylcellulose (A) has

a viscosity of at least 1,000 mPa»s, when measured as a 2 wt. % solution in water at 5 °C at a shear rate of 10 s ¹, and

anhydroglucose units joined by 1-4 linkages wherein hydroxy groups of anhydroglucose units are substituted with methyl groups such that s23/s26 is 0.36 or less, wherein s23 is the molar fraction of anhydroglucose units wherein only the two hydroxy groups in the 2- and 3 -positions of the anhydroglucose unit are substituted with methyl groups and s26 is the molar fraction of

anhydroglucose units wherein only the two hydroxy groups in the 2- and 6- positions of the anhydroglucose unit are substituted with methyl groups.

2. The hydrogel of claim 1 having at a temperature of 21°C a water content of from 50 to 94.0 weight percent, based on the total weight of the hydrogel.

3. The hydrogel of claim 1 or 2, wherein the viscosity of the methylcellulose (A) is from 2,000 to 100,000 mPa»s, when measured as a 2 wt. % solution in water at 5 °C at a shear rate of 10 s ¹.

4. The hydrogel of any one of claims 1 to 3, wherein the methylcellulose (A) has a degree of methyl substitution of from 1.55 to 2.25.

5. The hydrogel of any one of claims 1 to 4, wherein the polysaccharide (B) is a water-soluble cellulose ether being different from said methylcellulose (A).

6. The hydrogel of claim 5 wherein the polysaccharide (B) is a water-soluble C2-C3-alkyl cellulose, Ci-C3-alkyl hydroxy-Ci-3-alkyl cellulose, hydroxy-Ci-3-alkyl cellulose, mixed hydroxy-Ci-C3-alkyl cellulose, or mixed Ci-C3-alkyl cellulose.

7. The hydrogel of claim 6, wherein the polysaccharide (B) is a hydroxypropyl methylcellulose.

8. The hydrogel of any one of claims 1 to 7, wherein the polysaccharide (B) has a viscosity of at least 1000 mPa-s, determined as a 2.0 % by weight solution in water at 20°C.

9. The hydrogel of any one of claims 1 to 8, wherein the weight ratio between the methylcellulose (A) and the polysaccharide (B) is from 50 : 1 to 1 : 1.

10. The hydrogel of any one of claims 1 to 9, wherein additionally one or more active ingredients and/or one or more additives selected from coloring agents, pigments, opacifiers, flavoring agents, antioxidants, preservatives and salts are incorporated.

11. The hydrogel of any one of claims 1 to 10, having a gel fracture force G_F(21 °C) of at least IO N.

12. A process for producing a hydrogel from a methylcellulose (A) and water and additionally incorporating a non-starch water-soluble polysaccharide (B) being different from the methylcellulose (A) in the hydrogel, wherein the process comprises the steps of a) preparing an aqueous solution comprising at least 1.9 wt.-% of a methylcellulose (A), based on the total weight of the aqueous solution, and comprising a non- starch water- soluble polysaccharide (B), the methylcellulose (A) having a viscosity of at least 1,000 mPa^»s, when measured as a 2 wt. % solution in water at 5 °C at a shear rate of 10 s ¹, and having anhydroglucose units joined by 1-4 linkages wherein hydroxy groups of

anhydroglucose units are substituted with methyl groups such that s23/s26 is 0.36 or less, wherein s23 is the molar fraction of anhydroglucose units wherein only the two hydroxy groups in the 2- and 3-positions of the anhydroglucose unit are substituted with methyl groups and s26 is the molar fraction of anhydroglucose units wherein only the two hydroxy groups in the 2- and 6-positions of the anhydroglucose unit are substituted with methyl groups,

13. The process of claim 12, wherein in step b) the aqueous solution is heated to a temperature of at least 55 °C and in step c) the formed hydrogel is maintained for a time period of at least 1 hour at a temperature of at least 55 °C.

14. The process of claim 12 or 13, wherein the remaining water content in the hydrogel formed in step c) is from 50 to 94.0 weight percent, based on the total weight of the hydrogel.

15. The process of any one of claims 12 to 14, wherein in step a)

an aqueous solution comprising from 1.9 to 10 wt.-% of methylcellulose (A), based on the total weight of the aqueous solution, is prepared when the methylcellulose (A) has an s23/s26 of 0.27 or less or

an aqueous solution comprising from 2.5 to 20 wt.-% of a methylcellulose (A), based on the total weight of the aqueous solution, is prepared when the methylcellulose (A) has an s23/s26 of more than 0.27 and up to 0.36.