WO2016075371A1

WO2016075371A1 - Anionic parenchymal cellulose

Info

Publication number: WO2016075371A1
Application number: PCT/FI2015/050792
Authority: WO
Inventors: Antti Laukkanen; Jason Mckee; Tapio Saarinen; Henrikki Mertaniemi
Original assignee: Betulium Oy
Priority date: 2014-11-14
Filing date: 2015-11-13
Publication date: 2016-05-19
Also published as: EP3218416A1

Abstract

The present description is related to the field of parenchymal cellulose materials. It provides a method and a product for parenchymal cellulose derivative obtained by derivatizing parenchymal cellulose to comprise anionic substituents wherein the parenchymal cellulose derivative is capable of forming a continuous gel from an aqueous suspension at at least one point in a concentration range of from about 0.05 wt.% to about 99 wt.% based on total weight of the gel.

Description

ANIONIC PARENCHYMAL CELLULOSE

FIELD OF THE INVENTION

The present description is related to the field of anionic parenchymal cellulose based materials. More particularly, it provides novel anionic cellulose from a non-wood source, such as vegetable or beet waste products as well as food chain waste streams.

BACKGROUND

Cellulose is a substance of great industrial importance which has numerous applications. Primary source of cellulose in industrial applications is wood-based cellulose or cellulose derivatives. However, in using wood-based raw-material there are several problems such as environmental issues relating to unsustainable use of land and soil and heavy energy consumption required to grow, harvest and process wood-based material. . These issues have created a need to find, on one hand, alternative sources of cellulose for producing new cellulosic materials. Further, the industry is constantly searching for more economical methods and raw materials to produce high quality cellulosic products.

Spent sugar beet pulp is a by-product of the sugar beet processing industry. It comprises predominantly pectin, arabinogalactan and cellulose. Other naturally occurring biological constituents of sugar beets, such as fats, proteins, soluble oligosaccharides, and other low molecular weight components, are largely extracted from sugar beets during the removal of sucrose therefrom. The remaining polysaccharides in sugar beet pulp comprise generally conjugated, particulate cell residuals having morphologies generally characteristic of parenchymal cells found in certain higher plants.

Few economical uses have been found for spent parenchymal sugar beet pulp. For example, sugar beet pulp is a material which spoils rapidly and consequently constitutes a local environmental problem. In contrast to the solid residue obtained from the processing of sugar cane, sugar beet pulp has a negative fuel value and it takes more energy to dehydrate sugar beet pulp to a combustible state than can be recovered from its burning. Thus, alternative uses for parenchymal pulp are needed.

Previously, anionic cellulose and nanocellulose has been formed from wood-based cellulose. This process, however, requires energy intensive high-shear homogenization or grinding to form viscoelastic networks. A problem of the wood-based anionic cellulose is that the fibrillated gel cannot easily be concentrated for large-scale transportation. Hence, a method

l is needed that allows for viscoelastic networks with the ability to be concentrated using e.g. filtration techniques.

SUMMARY OF THE INVENTION

It is an aim of the present invention to solve or alleviate at least some of the problems related to prior cellulosic materials and their production methods, as discussed above. In particular, an aim of the present invention is to provide from novel raw material sources cellulosic materials that have a homogeneous distribution and good rheological properties in aqueous suspensions and/or good mechanical properties in a dry state.

Accordingly, as a first aspect there is provided a parenchymal cellulose derivative obtained by derivatizing parenchymal cellulose to comprise anionic substituents, wherein the parenchymal cellulose derivative is capable of forming a continuous gel from an aqueous suspension at at least one point in a concentration range of from about 0.1 wt.% to about 99 wt.% based on the total weight of the gel.

The present parenchymal cellulose derivative has several advantageous properties compared to wood-based cellulose and wood-based derivatives. Firstly, the present invention is able to utilize non-wood raw material from agricultural waste streams to produce cellulosic materials having improved rheological properties, thereby solving problems related to use of wood-based raw materials.

Further, the present invention is particularly advantageous as it provides an anionic cellulose derivative which has excellent gel and film forming properties that have many advantages when used in industrial applications.

Wood-based pulp forms a suspension, which settles out of the continuous phase without mechanical agitation. Typically, wood-based cellulose pulp requires high-shear fibrillation to form gels. This is a problem as the resulting systems cannot easily be concentrated, once fibrillated. Parenchymal-based chemically modified systems readily form gels even without high-shear fibrillation. The chemically modified gels can be concentrated using conventional filtration techniques, allowing for more efficient transportation, due to higher solids contents.

As the parenchymal cellulose derivative forms a continuous gel, large-scale fibrillation becomes feasible as the master batch forms a stable homogeneous gel. Hence, there will be no concentration gradients after the fibrillation process. In contrast, wood-based cellulose pulp settles out of the continuous phase, which can lead to concentration gradients in large- scale homogenization processes. The parenchymal cellulose derivative of the present invention or the composition comprising it may include a solvent in which the derivatized parenchymal cellulose is substantially insoluble at a high substitution degree or without anionic substitution. Suitable solvents include water, alcohol, and oil, with water being preferred. Thus, by selecting a suitable substitution degree, water-solubility of the derivatized material can be modified.

According to a second aspect there is provided a composition comprising nanofibrillar parenchymal cellulose derivative obtained by fibrillating the parenchymal cellulose derivative according to the first aspect.

According to a third aspect there is provided a composition comprising the parenchymal cellulose derivative according to the first aspect.

According to a fourth aspect there is provided a method of modifying rheological properties of a composition of matter, said method comprising the step of incorporating into said composition of matter the parenchymal cellulose derivative according to the first aspect, the fibrillated parenchymal cellulose derivative according to the first aspect, or the composition according to the second or the third aspect.

The present parenchymal cellulose derivative, as well as the compositions comprising it, are able to modify rheological properties of a composition of matter when incorporated or mixed into it. Accordingly, the present parenchymal cellulose derivative may be used to modify and improve one or more of the properties selected from viscosity, suspension stability, gel insensitivity to temperature, shear reversible gelation, yield stress, and liquid retention of the composition of matter. Compositions of matter whose rheological properties may be modified in this manner include foods, pharmaceuticals, nutraceuticals, personal care products, fibres, papers, paints, coatings, and construction compositions. More specifically, suitable compositions of matter include oral care products; creams or lotions for epidermal application, including moisturizing, night, anti-age, or sunscreen creams or lotions; food spreads, including reduced fat, low fat, or fat free food spreads (for example, mayonnaise); and drilling fluids. The modification of rheological properties can be further improved by using the fibrillated parenchymal cellulose derivative or compositions comprising it.

According to a fifth aspect there is provided a method of improving at least one of sizing, strength, scale control, drainage, dewatering, retention, clarification, formation, adsorbency, film formation, membrane formation, and polyelectrolyte complexation during paper or board manufacture, said method comprising the step of using the parenchymal cellulose derivative of the first aspect or the composition of the second or the third aspect. The use may include incorporation of the present parenchymal cellulose derivative or the present compositions into the paper or board. The rheological properties can be further improved by using the fibrillated parenchymal cellulose derivative or compositions comprising it.

According to a sixth aspect there is provided a method for improving the stability of an emulsion, suspension, or foam system, said method comprising the step of including in the system the parenchymal cellulose of the first aspect or the composition of the second or the third aspect. The stability can be further improved by using the fibrillated parenchymal cellulose derivative or compositions comprising it.

According to a seventh aspect there is provided a process for producing an anionic parenchymal cellulose gel or suspension, the process comprising following steps: a. providing parenchymal cellulose and optionally extracting it with an aqueous acid and/or an alkali solution to remove soluble polysaccharides; b. recovering the cellulosic residue and optionally bleaching the cellulosic residue; c. anionizing the cellulosic residue; d. harvesting the anionic cellulose as a gel or a suspension; and, optionally e. fibrillating the suspension or gel from step (d) wherein the fibrillation is carried out to provide improved rheological properties, such as increased yield stress, compared to the non-fibrillated gel or suspension.

In an embodiment the cellulose gel is a hydrogel. An advantage of the present method is that it can easily be implemented at the site where suitable raw material comprising parenchymal cellulose is produced. Also, the non-fibrillated chemically modified parenchymal can be concentrated by filtration techniques.

According to an eighth aspect there is provided an anionic parenchymal cellulose gel obtained by the above process. BRIEF DESCRIPTION OF THE FIGURES

Figs. 1A, 1 B, 1 C and 1 D disclose rheological properties of a non-fibrillated and fibrillated derivatized parenchymal cellulose made from potato pulp by anionization according to example 5. The aqueous suspensions are evaluated at 0.5 wt% concentration. Non- fibrillated sample (hollow symbols) and fibrillated sample (solid symbols). Fig 2. discloses results of the tensile test results of solvent-cast films.

Fig 3A, 3B, 3C and 3D disclose rheological properties of a fibrillated derivatized parenchymal cellulose made from sugar beet pulp by anionization according to example 6 to low degree of substitution. The aqueous suspensions are evaluated at 0.5 wt% concentration.

DETAILED DESCRIPTION

The parenchymal cellulose raw material, which is used to produce the cellulose microfibrils according to the present invention, may be obtained from a suitable plant source, including plant species that predominantly containing parenchyma cell types and/or wherein the majority of the cellulose is located in primary cell walls, or from a fully or partially fractionated part of a plant containing primary cell wall structures. Preferable raw materials include sugar beet, potato pulp, cassava pulp, citrus peel, sweet potato, corn, fruits, vegetables and mixtures thereof. Especially well suitable raw materials are sugar beet pulp, potato pulp, cassava pulp and mixtures thereof.

Raw materials of which soluble polysaccharides, such as pectin, have been at least partially removed by a raw material producer are especially well suitable raw materials. Examples of these kinds of materials are parenchymal cellulose rich side streams from pectin factories using e.g. citrus peel, apple residuals, or sugar beet as a pectin source. Correspondingly, parenchymal cellulose rich side streams from potato or cassava based starch factories are especially well suitable raw materials. In an embodiment the parenchymal cellulose raw material which is used to produce the parenchymal cellulose derivative according to the present invention is fresh, never dried, or dried.

The present parenchymal cellulose derivative is capable of forming a continuous gel in water throughout the concentration range of between about 0.05 % and about 99%, such as throughout the concentration range of between about 0.5 % and about 50 %, or at 0.1 %, 0.2%, 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1 %, 1 .5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, 5%, 5.5%, 6%, 6.5%, 7%, 7.5%, 8%, 8.5%, 9%, 9.5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 46%, 47%, 48%, 49%, 50%, 51 %, 52%, 53%, 54%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 91 %, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% in water. In an embodiment the parenchymal cellulose derivative is capable of forming a continuous gel from an aqueous suspension at at least one point in a concentration range of from about 0.1 wt.% to about 2 wt.% based on total weight of the gel. This concentration range is particularly useful for applications, as the parenchymal cellulose derivative forms a continuous stiff hydrogel at low solids content. However, the high water-content parenchymal cellulose derivative is laborious to transport in high quantities. Hence, concentration is required to higher solids content. In general, native cellulose is always in a microfibrillate form, these microfibrils being associated to a greater or lesser degree to form fibers, walls and membranes. Each cellulosic microfibril is constituted by a rigorous assembly of parallel cellulose chains resulting from the method by which the cellulose is biosynthesized. Cellulose microfibrils are generally considered to contain only few faults along their axis. Their mechanical properties are close to the theoretical mechanical properties of cellulose: a tenacity in the order of 130 GPa and a fracture toughness in the order of 13 GPa. Cellulosic microfibrils are thus of interest if they can be dissociated into single fibres.

Cellulose microfibrils are usually associated to a high degree in walls or fibers. The microfibrils in secondary walls are organized into highly oriented layers which form a fiber which cannot be dissociated; the microfibrils in primary walls are deposited in a disorganized fashion. The parenchyma is a typical example of primary wall tissue. While it is difficult, if not impossible, to separate secondary wall cellulose microfibrils without damaging them, it is easy to dissociate primary wall microfibrils, not only because of their looser organization but also because interstitial polysaccharides, which are usually anionically charged, constitute a large percentage of these walls. Preferably the parenchymal cellulose is obtained from purified, optionally bleached parenchymal cellulose. Even more preferably the cellulose is substantially free from wood- based cellulose structures present in secondary cell walls.

The substituent which provides an anionic charge to the derivatized parenchymal cellulose or chemically modifies the surface area, may be, or include, a group selected from the group consisting of carboxyl, carboxymethyl, sulphate, sulphonate, phosphonate, phosphate group, and halogenated compounds.

In an embodiment the anionizing reaction is carried out at alkaline conditions. The alkaline conditions may include contacting the cellulose material with a selected anionic reagent in the presence of an alkaline reagent which is sodium hydroxide, an oxide or hydroxide of an alkali metal or alkaline earth metal, an alkali silicate, an alkali aluminate, an alkali carbonate, an amine, ammonium hydroxide, tetramethyl ammonium hydroxide, or combinations thereof. Also, the anionizing reaction can proceed by oxidation of the hydroxyl groups located on the parenchymal surface area. Select catalysts can be activated at specific pH values. For example, TEMPO mediated oxidation proceeds more effectively in alkaline conditions. In an embodiment in the parenchymal cellulose derivative the anionic substituents result from derivatization through TEMPO-mediated oxidation or carboxymethylation, optionally having carboxylic acid content between 0.1 -0.7 mmol/g, preferably 0.2-0.5 mmol/g, and number average diameter below 10 nm. In an embodiment the parenchymal cellulose derivative not been TEMPO-oxidised.

Well suitable derivatization reactions are carboxymethylation and oxidation of parenchymal cellulose. Especially the TEMPO-mediated oxidation, which guides the oxidation to C6 hydroxyl group, is a desirable derivatization reaction. Instead of TEMPO, also other N-oxyl - based molecules can be used as an oxidation catalyst, such as 4-hydoxy TEMPO. The anionic substituent in this context means an anionic group that is intentionally attached or created for example by oxidation into the parenchymal cellulose during the anionization stage. Thus, in this context, the anionic substituent does not mean anionic groups having their origin in, or that are occurring in, naturally present anionic moieties in parenchymal cellulose, such as uronic acid as described in Dinand et al. in US5964983. The derivatized parenchymal cellulose has preferably a degree of substitution which makes it highly dispersible in an aqueous medium. In an example embodiment the degree of substitution is at least 0.05, preferably at least 0.15. In an embodiment the degree of substitution is between about 0.05 and about 0.15, and more preferably between about 0.05 and about 0.3. Suitable degrees of substitution include 0.05, 0.06, 0.07, 0.08, 0.09, 0.1 , 0.1 1 , 0.12, 0.13, 0.14, 0.15, 0.16, 0.17, 0.18, 0.19, 0.2, 0,21 , 0.22, 0.23, 0.24, 0.25, 0.26, 0.27, 0.28, 0.29, 0.3, 0.31 , 0.32, 0.33, 0.34, 0.35, 0.36, 0.37, 0.38, 0.39, 0.4, 0.41 , 0,42, 0.43, 0.44, 0.45, 0.46. 0.47, 0.48, 0.49 0.5, 1 ,0 and 1.5.

The derivatized parenchymal cellulose forms a continuous gel when suspended in water, even at low concentration. A continuous gel in this context means a mixture of derivatized parenchymal cellulose and water, where the derivatized parenchymal cellulose component does not settle out of the continuous phase at rest and where G'>G", where G' is the dynamic storage modulus and G" is the dynamic loss modulus.

The tangent of the phase angle, i.e. the ratio of loss modulus (G") to storage modulus (G') is a useful quantifier of the presence and extent of elasticity in a fluid. tan(8) values of less than unity indicate elastic-dominant (i.e. solid-like) behavior and values greater than unity indicate viscous-dominant (i.e. liquid-like) behavior. In an example embodiment the parenchymal cellulose derivative has the property of forming from an aqueous suspension a film having a tensile strength higher than 40MPa.

In an example embodiment the parenchymal cellulose derivative is fibrillated to comprise nanofibrillar cellulose. Nanofibrillar cellulose in this context means cellulose microfibrils or a cellulose microfibril bundle isolated from the above-mentioned raw materials. The aspect ratio of microfibrils is typically very high; the length of microfibrils may be more than one micrometer and the number-average diameter is typically less than 200 nm, such as between 2 and 100 nm. The diameter of microfibril bundles may be greater but is usually less than 1 μιη. The smallest nanofibrils are similar to the so-called elemental fibrils, the diameter of which is typically 2 to 12 nm. The dimensions and fiber structures of nanofibrils or microfibril bundles depend on the raw material and the fragmentation method. Nanofibrillar cellulose may also contain other polysaccharides, such as pectin, the amount of which depends on the raw material used.

Fibrillated parenchymal cellulose can be isolated from the above-described cellulose- containing raw material with an apparatus suitable for the purpose, e.g. a grinder, comminutor, rotor-stator mixer or grinders such as Ultra-Turrax, Masuko from Masuko Sangyo, rotor-rotor mixers or grinders such as Atrex-type devices, homogenizer such as Ariete-type or Panda-type from GEA Niro-Soavi, fluidizer, micro- or macrofluidizer such as microfluidizer from Microfluidics and/or ultrasonic disintegrator. In an embodiment the parenchymal cellulose derivative is fibrillated to comprise nanofibrillar cellulose preferably having a number average diameter of 2-100nm, more preferably of 2- 10nm.

There are several widely used synonyms for nanofibrillar cellulose. For example: nanocei!ulose, microfibrillar cellulose, nanofibrillated cellulose, cellulose nanofiber, nano- scale fibrillated cellulose, microfibriliated cellulose (MFC), or cellulose microfibrils.

After fibrillation the parenchymal cellulose derivative of the present invention has improved rheological properties and the resulting gel comprising the fibrillated cellulose in an aqueous medium has increased viscosity and yield stress. Also, the properties of a film produced from the resulting gel or suspension by removing water are improved compared to a film from non- fibrillated material. In particular, such a film has improved tensile strength and optical properties compared to a film produced accordingly from non-fibrillated cellulose.

The derivatized, optionally fibrillated, parenchymal cellulose may be used to modify one or more of the viscosity, suspension stability, gel insensitivity to temperature, shear reversible gelation, yield stress, and liquid retention of the composition of matter. Compositions whose rheological properties may be modified in this manner include foods, pharmaceuticals, nutraceuticals, personal care products, fibres, papers, paints, coatings, and construction compositions. More specifically, possible compositions include oral care products; creams or lotions for epidermal application, including moisturizing, night, anti-age, or sunscreen creams or lotions; food spreads, including reduced fat, low fat, or fat free food spreads (for example, mayonnaise); and drilling fluids.

Alternatively, the derivatized parenchymal cellulose may be incorporated into a coating composition in order to improve its physical and/or mechanical properties. Those properties may include one or more of film forming, levelling, sag resistance, strength, durability, suspension, flooding, floating, and spatter. The present cellulose derivative may be added as a gel, film, or powder.

The present anionic cellulose may further be used in the manufacture of paper and paper products in order to improve at least one of sizing, strength, scale control, drainage, dewatering, retention, clarification, formation, absorbency, film formation, membrane formation, and polyelectrolyte complexation during manufacture. Fibrillated present anionic cellulose is particularly preferred for use in this method.

In one embodiment of this method, the present anionic cellulose may be used to increase the rate of drainage and/or dewatering during paper manufacture. In another embodiment, the present anionic cellulose may be used for retention of organic and/or inorganic dispersed particles in a sheet of paper during its manufacture. Representative dispersed particles which may be retained in this manner include pulp fines, fillers, sizing agents, pigments, clays, detrimental organic particulate materials, detrimental inorganic particulate materials, and combinations thereof. Additionally, the present anionic cellulose may be used in a papermaking machine to improve the strength of a sheet of paper produced on a paper machine. Fibrillated anionic parenchymal cellulose according to the invention is particularly preferred for use in this method.

In each of the present embodiments the anionic cellulose may be used in the presence of one or more of the following: colloidal silica; colloidal aluminium modified silica; colloidal clay, derivatives of starch containing carboxylic acid functionality, hydroxyl groups, amines and other polar and nonpolar functional groups; derivatives of guar gum containing carboxylic acid functionality, hydroxyl groups, amines and other polar and nonpolar functional groups; natural gums or derivatized natural gums containing carboxylic acid functionality, hydroxyl groups, amines and other polar and nonpolar functional groups; polyesters, polyamines, polyurethanes, polyacrylamides, polyacrylates, poly methacrylates and polystyrenics containing carboxylic acid functionality, hydroxyl groups, amines and other polar and nonpolar functional groups; and combinations thereof. Fibrillated anionic cellulose according to the invention is particularly preferred for use in this method. The present derivatized cellulose may further be used in a method for improving the stability of an emulsion, suspension, or foam system, by including the derivatized cellulose in the system. Where the system being treated is an emulsion, the emulsion may be produced by processing of an emulsion formulation, in which case the derivatized cellulose may be added to the emulsion formulation prior to completion of processing of the emulsion formulation. Fibrillated anionic cellulose according to the invention is particularly preferred for use in this method.

In an example embodiment the parenchymal cellulose derivative has a yield stress of 0.1 to 100 Pa at 0.5% aqueous suspension.

In an example embodiment the fibrillated parenchymal cellulose derivative has a property of being capable of forming a film which has a tensile strength which is higher after fibrillation. The film may be formed from an aqueous suspension by removing water.

In an example embodiment the fibrillated parenchymal cellulose derivative has a property of being capable of forming a gel having a yield stress which is higher after fibrillation. The gel may be formed by suspending the present parenchymal cellulose derivative with water. In an example embodiment in the process for preparing of an anionic parenchymal cellulose the parenchymal cellulose derivative is from sugar beet and/or potato and either before step a, or after step b, d, or e of the above process the cellulosic material is bleached with a bleaching agent. Suitable bleaching agents include NaCIC>2, H2O2, ozone, sodium hypochlorite, sodium chlorite, chlorine dioxide. In an example embodiment the degree of carboxylic groups can be increased using a two- step bleaching process, for example by using the procedure of Example a. Without binding to any theory, the hypochlorite bleaching procedure results in aldehyde groups attached to the cellulose fibril surface. The following bleaching process that utilized sodium chlorite as an oxidant, results in the aforementioned aldehydes oxidizing into carboxylic acids. By bringing more anionic groups to the fibril surface, using the aforementioned two-step bleaching process, the pulp's rheological properties are promoted both before and after fibrillation (Example a). In an example embodiment the carboxylic acid content of the bleached parenchymal cellulose derivative is between 0.05 and 0.6 mmol/g, preferably between 0.05 and 0.2 mmol/g, even more preferably between 0.1 and 0.15 mmol/g. At this level the ensuing pulp can be easily nanofibrillated by running it once through a homogenizer at 600 bar. Preferably the bleaching is the two-step bleaching as described below.

In an embodiment the anionic substituents result from de vatization through TEMPO- mediated oxidation or carboxymethylation, optionally to have carboxylic acid content between 0.1 -0.6 mmol/g, preferably 0.2-0.5 mmol/g such as 0.49mmol/g, and number average diameter below 15 nm. The ensuing pulp is nanofibrillated by running it once through a homogenizer at 600 bar. In prior art, it has been claimed that carboxylic acid content of oxidized wood pulp has to be above 0.8 mmol/g to enable similar level of fibrillation. Thus, for TEMPO oxidized parenchymal cellulose, a simple and more economical nanofibril- lation process can be used for low acid carboxylic acid derivative.

In an example embodiment the parenchymal cellulose derivative has not been TEM- PO-oxidised.

In an example embodiment the process comprises a two-step bleaching step, wherein in step b. aldehyde groups are introduced in the cellulosic residue; and anionizing in step c. comprises oxidizing at least partially the aldehyde groups formed in step b.

In an example embodiment in the process step b. aldehyde groups are introduced to at least 0.02-0.2mmol/g, preferably to an amount 0.02-0.15mmol/g, more preferably to 0.12mmol/g.

In an example embodiment in the process aldehyde groups are introduced using hypochlorite and step c. comprises anionizing using an agent selected from chlorite, sodium chlorite, chlorine dioxide, ozone, hydrogen peroxide, or a mixture thereof.

In an example embodiment in the process in step c. anionization is carried to an amount selected fro the range between 0.05 and 0.2 mmol/g, preferably between 0.1 and 0.2 mmol/g, most preferably between 0.1 and 0.15 mmol/g.

In an example embodiment anionizing is carried out using TEMPO oxidation. Preferably in step c. anionization is carried to an amount selected from the range between 0.2 and 1 .5 mmol/g, preferably 0.3-1.0 mmol/g, most preferably 0.3-0.8mmol/g. In an example embodiment in the process the parenchymal cellulose is selected from a group comprising any of: sugar beet, bagasse, cassava and potato, the process optionally comprising bleaching the cellulosic material either before a. or after b., d., or e. In an example embodiment the process further comprises concentrating the anionic parenchymal cellulose suspension.

In an example embodiment in the process for preparing an anionic parenchymal cellulose the process further comprises concentrating the anionic parenchymal cellulose gel obtained in the process.

EXAMPLES

The following examples are provided to illustrate various aspects of the present invention. They are not intended to limit the invention, which is defined by the accompanying claims.

Example 1. Purification of potato pulp

Dry dehydrated potato pulp was purified in a lye wash. Here, the potato pulp (solids 2500 g) was taken to a 25 g/L suspension and heated to 60-90°C. With gentle stirring, 20 g/L NaOH was added. During this time, the hydrated potato clippings lost their solid-like morphology and broke down into a dark brown viscous mass within a minute. After 120 minutes of stir- ring, the reaction was cooled down and filtrated through a steel screen (0.25 mm pore size). The lye-washed pale grey cellulosic potato mass was further washed with copious amounts of water.

Example 2. Purification of sugar beet pulp

Dry dehydrated sugar beet pulp was purified in a two-step process. Sugar beet clipping (2500 g) were taken to a 25 g/L suspension. The pH of the reaction suspension was set to 2, using 1.0 M HCI. The suspension of sugar beet pulp was heated to 70-80 degrees and gently stirred for 120 minutes. Next, the ensuing beet clippings were filtered through a steel mesh screen (0.25 mm pore size) and further washed with copious amounts of deionized water.

After the acid wash, the hydrated sugar beet pulp was washed in lye. Here, pulp was taken to a 25 g/L suspension and heated to 70-80°C. With gentle stirring, 20 g/L NaOH was added. During this time, the hydrated beet clippings lost their solid-like morphology and broke down into a dark brown viscous mass. After 120 minutes of stirring, the reaction was cooled down and filtrated through a steel screen (0.25 mm pore size). The lye-washed pale grey cellulosic sugar beet mass was further washed with copious amounts of water.

Example 3. Bleaching of potato pulp

After the one- or two-step washing procedure (see Example 1 &2), the purified potato-based parenchymal cellulose was bleached using sodium chlorite (NaCI02). The purified potato pulp (solids: 1000 g) mass was taken up to a 25 g/L slurry, heated to 70-80°C and subsequently buffered to pH 4.9 with acetic acid. Then a NaCI02 powder (3.4 g/L, 136 g, 1 .5 mol) was stirred into the reaction. The reaction was then allowed to proceed without any stirring.

After three hours, the mass was filtered through a polyester mesh (pore size 0.5 mm). The ensuing bleached potato mass was further washed with copious amounts of deionized water.

Example 4. Bleaching of sugar beet pulp

After the two-step washing procedure (see Example 2), the purified beet-based parenchymal was bleached using sodium chlorite (NaCIC>2). The purified sugar beet pulp (solids: 65.5 g) mass was taken up to a 25 g/L slurry, heated to 70-80°C and subsequently buffered to pH 4.9 with acetic acid. Then a NaCIC>2 powder (3.4 g/L, 8.9 g, 0.098 mol) was stirred into the reaction.

After three hours stirring, the slurry was filtered through a polyester mesh (pore size 0.5 mm). The ensuing bleached sugar beet mass was further washed with copious amounts of deionized water.

Example 5. TEMPO-mediated oxidation of bleached potato pulp

First, TEMPO (2.3 g, 0.015 mmol) and NaBr (53.8 g, 0.520 mol) were dissolved into deionized water (1000 I). Bleached potato pulp (see example 2) (1 12.5 g dry weight) was suspended into 2700 mL deionized water and the pH was set to 10 with 1 M NaOH. This suspension was slowly stirred for 30 minutes and then the dissolved TEMPO/NaBr (1000 mL) solution was added. The pH was set to 10.5 and the suspension was stirred for another 30 minutes.

An aqueous sodium hypochlorite (NaCIO) aqueous solution (312.5 mL, 13% solution) was diluted with deionized water (600 mL). To start the oxidation process, the 600 mL NaCIO solution was divided into three aliquots and added sequentially. The first aliquot (200 mL) was added and the pH was lowered to 10.3. with 1 M HCI. There was a constant decrease in the pH, due to the emerging carboxylate groups. Consequently, the pH was kept at a standard 10.3 with constant addition of 1 M NaOH. After 10 minutes, the next NaCIO aliquot (600 mL) was added. Similarly, the reaction was kept at a standard pH of 10.3 until the formation of carboxylate groups stopped (-10-40 minutes). Finally, the rest of the NaCIO solution was added, followed by another 10-20 minute mixing at pH 10.3.

The TEMPO oxidized potato mass was subsequently filtered through a steel mesh (pore size 0.25 mm). The first filtration was done in basic media, where the reaction components were washed out. The second filtration was done at pH 2 and finally the product was neutralized and washed with copious amounts deionized water. The pH of the resulting mass was set to 8-9. The mass readily formed a hydrogel.

Acid-base titration was used to determine the amount of carboxylate groups located on the nanofibrillar surface. First, TEMPO-oxidized potato mass (200-300 mg) was suspended into 50 mL deionized water and the pH was adjusted to 2.0-2.5. This slurry was then titrated with 0.1 M NaOH. According to conductiometric titration, the amount of acid-groups was calculated to be approximately 0.7-0.8 mmol/g.

Example 6. TEMPO-mediated oxidation of bleached sugar beet pulp

First, TEMPO (0,91 g, 5.8 mmol) and NaBr (21 .53 g, 210 mmol) were dissolved into deionized water (750 I). Bleached sugar beet pulp (see example 2) (45 g dry weight) was suspended into 3000 mL deionized water and the pH was set to 10 with 1 M NaOH. This suspension was slowly stirred for 30 minutes and then the dissolved TEMPO/NaBr (750 mL) solution was added. The pH was set to 10.5 and the suspension was stirred for another 30 minutes. An aqueous sodium hypochlorite (NaCIO) aqueous solution (125 mL, 13% solution) was diluted with deionized water (350 mL). To start the oxidation process, the 475 mL NaCIO solution was divided into three aliquots and added sequentially. The first aliquot (100 mL) was added and the pH was lowered to 10.3 with 1 M HCI. There was a constant decrease in the pH, due to the emerging carboxylate groups. Consequently, the pH was kept at a standard 10.3 with constant addition of 1 M NaOH. After 10 minutes, the next NaCIO aliquot (300 mL) was added. Similarly, the reaction was kept at a standard pH of 10.3 until the formation of carboxylate groups stopped (-10-40 minutes). Finally, the rest of the NaCIO solution was added, followed by another 10-20 minute mixing at pH 10.3.

The TEMPO oxidized sugar beet mass was subsequently filtered through a steel mesh (pore size 0.25 mm). The first filtration was done in basic media, where the reaction components were washed out. The second filtration was done at pH 2 and finally the product was neutralized and washed with copious amounts deionized water. The pH of the resulting mass was set to 8-9. The mass readily formed a hydrogel.

Acid-base titration was used to determine the amount of carboxylate groups located on the nanofibrillar surface. First, TEMPO-oxidized sugar beet mass (200-300 mg) was suspended into 50 mL deionized water and the pH was adjusted to 2.0-2.5. This slurry was then titrated with 0.1 M NaOH. According to conductiometric titration, the amount of acid-groups was calculated to be approximately 0.7-0.8 mmol/g. Example 7. Fibrillation of derivatized parenchymal cellulose based on potato pulp

The rheological properties could be further promoted by high-pressure homogenization of the derivatized parenchymal cellulose (see Example 5). By running chemically derivatized potato pulp suspension (25 g/L) through a fluidizer (Microfluidics M-1 10) at 1800 bar bar 1 time, the rheological properties were promoted. The fibrillation pressure can also be lower (e.g. 600 bar) without seriously affecting the fibrillation result.

Example 8. Fibrillation of derivatized parenchymal cellulose based on sugar beet.

The rheological properties could be further promoted by high-pressure homogenization of the chemically derivatized sugar beet pulp (see Example 6). By running the oxidized sugar beet pulp (25 g/L) through a fluidizer (microfluidics M-1 10) at 1800 bar 1 time, the rheological properties were promoted. The fibrillation pressure can also be lower (e.g. 600 bar) without seriously affecting the fibrillation result.

Example 9. Rheological characterization of fibrillated and non-fibrillated derivatized parenchymal cellulose based on potato pulp Rheological measurements

The measurements were performed at 25 C using a dynamic rotational rheometer (HR-2, TA Instruments). The geometry used was stainless steel concentric cylinders geometry, bob and cup radii 14.02 and 15.20 mm, fulfilling the standard ISO 3219/DIN 53019.

The measurement routine for fibrillated cellulose suspensions is presented in Table 1 The purpose of the peak hold and time sweep interval in between amplitude sweep, frequency sweep and both shear stress and shear rate controlled stepped flow intervals was to set a comparable shear history to the samples. The linear viscoelastic region was determined with an oscillatory amplitude sweep. Frequency sweep was performed to probe the fiber network structure at rest, and stepped flow curves were to characterize the flow properties of the suspensions. Shear stress controlled flow curve may be better able to reveal yielding in the suspension, whereas shear rate controlled flow curve is more directly linked to the flow rate, i.e. rate of deformation in the suspension structure. Table 1. Rheological measurement intervals.

a) pt is short for point time, 15 s, of which the average of last 5 s recorded

The rheological behavior of the potato pulp based derivatized parenchymal cellulose sam- pies is presented in Fig. 1A-D. In common with both non-fibrillated and fibrillated samples, they exhibit gel like behavior: Storage modulus G' (Fig. 1A) is over the loss modulus G" (not presented) over wide range of frequencies as is evident by the tan(8) < 1 (Fig. 1 B). In other words, the response is elastically dominated. Both samples are also markedly shear thinning in steady shear experiments (Fig. 1 D) and show yield stress type of behavior (steady plateau in viscosity levels before the collapse at yield point, Fig. 1 C).

Fibrillation improves the gel structure to a degree. The storage moduli and tan(8) are not changed markedly, but the yield stress (Fig 1 C) and viscosity as a function of shear rate (Fig. 1 D) are elevated. The structure of the samples was homogeneous, continuous gel structure without observable phase separation during the experiment or the preceding storage time. Fibrillation turns the sample from opaque to transparent.

Example 10. Rheological characterization of fibrillated derivatized parenchymal cellulose based on sugar beet pulp

Rheological measurements The measurements were performed at 25 °C using a dynamic rotational rheometer (HR-2, TA Instruments). The geometry used was stainless steel concentric cylinders geometry, bob and cup radii 14.02 and 15.20 mm, fulfilling the standard ISO 3219/DIN 53019.

The measurement routine for fibrillated cellulose suspensions is presented in Table 2. The purpose of the peak hold and time sweep interval in between amplitude sweep, frequency sweep and both shear stress and shear rate controlled stepped flow intervals was to set a comparable shear history to the samples. The linear viscoelastic region was determined with an oscillatory amplitude sweep. Frequency sweep was performed to probe the fiber network structure at rest, and stepped flow curves were to characterize the flow properties of the sus- pensions. Shear stress controlled flow curve may be better able to reveal yielding in the suspension, whereas shear rate controlled flow curve is more directly linked to the flow rate, i.e. rate of deformation in the suspension structure.

Table 2. Rheological measurement intervals.

a) pt is short for point time, 15 s, of which the average of last 5 s recorded

Results. The rheological behavior of the fibrillated anionic sugar beet pulp sample in Fig. 3 A-D. Fig. 3 A shows constant G' level at 0.5 wt% consistency. Correspondingly, Fig. 1 B shows the calculated tan(8) rheological behavior is typical for a gel: G' is constant over wide range of frequencies, and the tan(8) < 1 , i.e. the response is elastically dominated ( G' > G"). The sample is also markedly shear thinning in steady shear experiments (Fig. 3D) and shows yield stress type behavior (Fig. 3C). The structure of the sample was homogeneous, continuous gel structure without observable phase separation during the experiment or the preceding storage time. After fibrillation, rheological properties were increased when compared to non-fibrillated sample.

Example 11. Mechanical characterization of solvent cast films Sample preparation

Materials were solvent cast as follows. Samples were diluted to a solid content suitable for solvent casting, typically 0.4-1 .0 wt.%, and degassed in vacuum to remove bubbles formed due to mixing. An amount containing 100 mg of solids was applied onto a plastic petri dish (diameter 50 mm). The samples were dried in an oven at 60°C until they appeared dry. The films were removed from the petri dishes, and the drying was continued for at least 4 h between blotting papers at a temperature above 100°C.

Tensile testing

The solvent-cast films were cut to 2 mm wide strips for mechanical testing. The thickness of each strip was measured using a Mitutoyo film thickness gauge. Thickness was measured at three points, and the average was used for data analysis. Before tensile testing, the samples were stored at a controlled humidity (RH 50%, 20°C) overnight. Tensile tests were performed using a Kammrath & Weiss tensile tester with a 100 N load cell. The grip separation in the starting position was 10 mm. Sample strips were elongated at 1 .00 mm/min, and the force and elongation were measured at a sampling frequency of 20 Hz. From each film, 5-6 strips were measured.

Tensile data analysis

Tensile strength, elastic modulus, strain (elongation) at break, and the modulus of toughness (i.e., the area under the stress-strain curve) were determined separately from each single measurement. The mean values for each property are tabulated together with standard error of mean. An average curve was generated by calculating the average of stresses at each strain point until the average strain at break, linearly interpolating the measured data for each point. Before calculating the average curve, the data from the samples that broke before average were linearly extrapolated until the average strain at break.

Samples Three different samples were evaluated. Sample 1 is a non-fibrillated TEMPO-oxidized hard wood sample where the amount of acid-groups was calculated to be approximately 1 .3 mmol/g. The sample was synthesized according to method described by Saito et al. (Saito, T., Nishiyama, Y., Putaux, J., Vignon, M., Isogai, A. (2006): Homogeneous suspensions of individualized microfibrils from TEMPO-catalyzed oxidation of native cellulose, Biomacromol- ecules, 7 (6), 1687-1691 ). The sample 2 is a non-fibrillated derivatized parenchymal cellulose sample based on potato pulp, described in example 5. The sample 3 is fibrillated derivate of the sample 2, i.e. described in example 7.

Results

The tensile testing results are shown in Fig. 2, and the values are tabulated in Table 3. The results show that in comparison with Sample 1 , Sample 2 has considerably larger strength, ductility, stiffness, and toughness; characterized by tensile strength, strain at break, elastic modulus, and modulus of toughness, respectively. Furthermore, Sample 3 has larger tensile strength and elastic modulus than Sample 2. Based on the results, it is evident that the dry film structures made of the derivatized parenchymal based cellulose material have better mechanical properties compared to the wood pulp based structures. The fibrillation further improves the properties.

Table 3. Mechanical properties with the standard error.

Example a - Two-step bleaching procedure (Samples 182 & 195)

After the washing procedure (see Example 1 ), purified potato pulp was first bleached using sodium hypochlorite (NaOCI). Here, base extracted potato pulp (solids: 1050 g) was diluted to a low consistency slurry and 1700 ml of NaOCI (124.5 act. Cl/L) was stirred into the reaction. Subsequently, the pH was adjusted to 7.5 with sulfuric acid and the reaction was then allowed to proceed without any stirring in room temperature. Final reaction volume was 70L (1 .5% consistency) and overall NaOCI loading was 2.39g NaOCI / 1 g pulp.

After the reaction, the pulp was filtered through a stainless steel mesh (pore size 0.1 mm). The ensuing bleached potato mass was further washed with copious amounts of water. The final yield was 68.9% including losses in washing. Carboxylic content was measured as 0.06 mmol/g using conductiometric titration (Example e).

The rheological properties could be further promoted by high-pressure homogenization (see Example h and Tables 1 & 2) (Sample 182). The resulting fibrillated parenchymal cellulose was characterized using turbidity and viscosity measurements, characteristic values are summarized in Table 1 . Transmission electron microscopy was used to evaluate dimensions of a typical product (Table 1 ).

After NaOCI bleaching procedure, the sodium hypochlorite bleached potato pulp was further bleached using sodium chlorite (NaCI02) (Sample 195). The once bleached potato pulp (solids: 80 g) mass was diluted to low consistency and heated to 80°C. Thereafter, NaCI02 (3.4 g/L, 15.3 g) was stirred into the reaction and the pH was adjusted to 3.6 using sulfuric acid. The final reaction volume was 4.5 L with a 1.67% pulp consistency. The reaction was then allowed to proceed with mechanical stirring for 4 hours and the temperature was kept be- tween 70 - 80°C.

After the reaction, the mass was filtered through a polyester mesh (pore size 0.25 mm). The ensuing bleached potato mass was further washed with copious amountsof water. Carboxylic content was measured as 0.12 mmol/g using conductiometric titration (Example e).

The rheological properties could be further promoted by high-pressure homogenization (see Example h and Tables 1 & 2) (Sample 195). The resulting fibrillated parenchymal cellulose was characterized using turbidity and viscosity measurements, characteristic values are summarized in Table 1 . Transmission electron microscopy was used to evaluate dimensions of a typical product (Table 1 ).

Example b - High solids bleaching of sugar beet pulp

After the washing procedure (see Example 1 ), the base extracted sugar beet pulp (10 wt.%) was bleached using sodium hypochlorite (NaOCI). Here, base extracted sugar beet pulp (solids: 94 g) was combined with 75 ml of NaOCI (13 % solution) was mixed into the reaction. Subsequently, the pH was adjusted to 7.5 with sulfuric acid and the reaction was then al- lowed to proceed without any stirring in room temperature. Final reaction volume was 1 L (9.4 wt.%).

After the reaction, the pulp was filtered through a stainless steel mesh (pore size 0.1 mm). The ensuing bleached potato mass was further washed with copious amounts of water.

The rheological properties could be further promoted by nanofibrillation, preferably by using the method of Example i.

Example c - TEMPO-oxidation of non-bleached potato pulp (Sample 140)

TEMPO (2.3 g, 0.015 mmol) and NaBr (53.8 g, 0.520 mol) were dissolved into deionized water (1000 I). Non-bleached potato pulp (see example 1 ) (1 12.5 g dry weight) was suspended into 2700 mL deionized water and the pH was set to 10 with 1 M NaOH. This suspension was slowly stirred for 30 minutes and then the dissolved TEMPO/NaBr (1000 mL) solution was added. The pH was set to 10 and the suspension was stirred for another 30 minutes.

To start the reaction, aqueous sodium hypochlorite (NaCIO) aqueous solution (550 mL, 10% solution) was slowly added to the stirred suspension, while keeping the pH at a level 10. The added sodium hypochlorite simultaneously bleached the potato pulp and oxidized it.

The bleached and TEMPO oxidized potato mass was subsequently filtered through a steel mesh (pore size 0.25 mm). The first filtration was done in basic media, where the reaction components were washed out. The second filtration was done at pH 2 and finally the product was neutralized and washed with copious amounts deionized water. The pH of the resulting mass was set to 8-9.

Conductiometric titration was used to determine the amount of carboxylate groups located on the nanofibrillar surface (1 .3 mmol /g) (Example e).

The rheological properties could be promoted by high-pressure homogenization (see Example h and Tables 1 & 2) (Sample 140). The resulting fibrillated parenchymal cellulose was characterized using turbidity and viscosity measurements, characteristic values are summarized in table 2. Transmission electron microscopy was used to evaluate dimensions of a typical product (Table 1 ).

Example d - Low carboxylic acid content TEMPO-oxidation of bleached potato pulp (Sample 193) First, 85ml (1 14.8g act CI / L, total 137.6 mmol) of hypochlorite was diluted into 500 ml of deionized water. Then TEMPO (1 .88 g, 12 mmol) and NaBr (42.8 g, 416 mmol) were dissolved into deionized water (200 ml) and 100 ml of the hypochlorite mixture. Then NaOCI bleached potato pulp (see example a) (67.5 g dry weight) was suspended into deionized water and the pH was set to 10 with 1 M NaOH. Pulp suspension was slowly stirred for 30 minutes with mechanical stirrer and the TEMPO/NaBr/NaOCI mixture was added. The remaining hypochlorite was added during the next 30 seconds so that pH remained between 10.0 - 1 1.0. Formation of -COOH continued for the next few minutes while the pH was kept at 10.5 with NaOH addition. The suspension was stirred for another 30 minutes to ensure completion. The TEMPO oxidized potato mass was subsequently filtered through a steel mesh (pore size 0.25 mm). The first filtration was done in basic media, where the reaction components were washed out. The second filtration was done at pH 2 and finally the product was neutralized and washed with copious amounts of deionized water. The pH of the resulting mass was set to 8-9. Conductiometric titration was used to determine the amount of carboxylate groups located on the nanofibrillar surface (0.49 mmol /g) (Example e)

The rheological properties could be further promoted by high-pressure homogenization (see Example h and Tables 1 & 2). The resulting fibrillated parenchymal cellulose was characterized using turbidity and viscosity measurements, characteristic values are summarized in Table 1 . Transmission electron microscopy was used to evaluate dimensions of a typical product (Table 1 ).

Example e - Carboxylic content measurement with conductiometric titration

Bleached and oxidized pulp was diluted to low consistency (~1 %) and pH was adjusted to 2 - 3 with 1 M HCI. After 30 minutes pulp was washed with deionized water until conductivity was below 5 μ8/οπ"ΐ. Carboxylic content was subsequently determined with Titrino automatic titrator. Titration velocity was 0.1 ml / min (0.1 mmol NaOH / ml) and titration time was 4800 minutes. Conductivity was recorded every 30 seconds.

Example g - Characterization methods

The viscosity of the fibrillated parenchymal cellulose was measured by Brookfield DV3T viscosimeter (Brookfield Engineering Laboratories, Middleboro, USA) equipped with a vane geometry (V-72, diameter 21.67 mm, length 43.38 mm). The product was diluted with water to 0.5 % w/w and the sample was agitated for 10 min before the measurement followed by degassing in vacuum to remove the entrapped air bubbles in the sample. The temperature was adjusted to 20 °C prior to measurements. The viscosity of the samples was measured at 50 and 100 rpm shear rates.

Turbidity of dilute aqueous suspensions of fibrillated parenchymal cellulose was measured with HACH P2100 turbidimeter. The product was diluted with water to a concentration of 0.1 wt%, and the sample was agitated for 10 min before the measurement followed by degassing in vacuum to remove the entrapped air bubbles in the sample. The temperature was adjusted to 20 °C prior to the measurement where the emission of light scattered from particles of a sample was detected.

Table 1 . Summary of the turbidity, viscosity results and mean fibril diameters.

Table 2. Summary of the raw material information and fibrillation methods.

Example h. High-pressure homogenization of anionic pulp

The rheological properties could be further promoted by high-pressure homogenization of the anionic pulp (see Examples 2, 3 & 4). By running the pulp suspension (pH between 8 and 10) through a homogenizer at 600 bar between 1 to 4 times, the rheological properties were promoted.

Example i. Nanofibrillation of anionic pulp using a rotor mixer

The rheological properties could be further promoted by nanofibrillation of the anionic pulp. By running the pulp suspension through (pH between 8 and 10) a rotor mixer at 1800 rpm between 1 to 4 times, the rheological properties were promoted.

The foregoing description has provided, by way of non-limiting examples of particular implementations and embodiments of the invention, a full and informative description of the best mode presently contemplated by the inventors for carrying out the invention. It is however clear to a person skilled in the art that the invention is not restricted to details of the embodiments presented in the foregoing, but that it can be implemented in other embodiments using equivalent means or in different combinations of embodiments without deviating from the characteristics of the invention.

Furthermore, some of the features of the afore-disclosed embodiments of this invention may be used to advantage without the corresponding use of other features. As such, the foregoing description shall be considered as merely illustrative of the principles of the present invention, and not in limitation thereof. Hence, the scope of the invention is only restricted by the appended patent claims.

Claims

1 . A parenchymal cellulose derivative obtained by derivatizing parenchymal cellulose to comprise anionic substituents wherein the parenchymal cellulose derivative is capable of forming a continuous gel from an aqueous suspension at at least one point in a concentration range of from about 0.05 wt.% to about 99 wt.% based on total weight of the gel.

2. The parenchymal cellulose derivative of claim 1 capable of forming a continuous gel from an aqueous suspension at at least one point in a concentration range of from about 0.1 wt.% to about 2 wt.% based on total weight of the gel.

3. The parenchymal cellulose derivative of claim 1 or 2 having a property of forming from an aqueous suspension a film having a tensile strength higher than 40MPa.

4. The parenchymal cellulose derivative of any one of claims 1 -3 wherein the parenchymal cellulose comprises cellulose from sugar beet, bagasse, cassava, and/or potato.

5. The parenchymal cellulose derivative of any one of claims 1 -4 fibrillated to comprise nanofibrillar cellulose preferably having a number average diameter of 2-100nm, more preferably of 2-1 Onm.

6. The parenchymal cellulose derivative of any one of claims 1 -5 wherein the carboxylic acid content of the parenchymal cellulose derivative is between 0.05 and 0.6 mmol/g, preferably between 0.05 and 0.2 mmol/g, even more preferably between 0.1 and 0.15 mmol/g.

7. The parenchymal cellulose derivative of claim 5 or 6 having a property of being capable of forming a film which has a tensile strength which is higher after fibrillation.

8. The parenchymal cellulose derivative of claim 5 or 6 having a property of being capable of forming a gel which has a yield stress which is higher after fibrillation.

9. The parenchymal cellulose derivative of any one of claims 1 -8 wherein the anionic substituents result from derivatization through TEMPO-mediated oxidation or carboxymethylation, optionally to have carboxylic acid content between 0.1 -0.6 mmol/g, preferably 0.2-0.5 mmol/g, and number average diameter below 15 nm.

10. The parenchymal cellulose derivative of any one of claims 1 -8 wherein the parenchymal cellulose derivative has not been TEMPO-oxidised.

1 1 . Composition comprising nanofibrillar parenchymal cellulose derivative obtained by fibrillating the parenchymal cellulose derivative of any one of claims 1 -4.

12. Composition comprising the parenchymal cellulose derivative of any one of claims 1 -1 1 .

13. A method of modifying rheological properties of a composition of matter, said method 5 comprising the step of incorporating into said composition of matter the parenchymal cellulose derivative according to any one of claims 1 -10 or the composition of claim 1 1 or 12.

14. A method of improving at least one of sizing, strength, scale control, drainage, dewatering, retention, clarification, formation, adsorbency, film formation, membrane

10 formation, and polyelectrolyte complexation during paper or board manufacture, said method comprising the step of using the parenchymal cellulose derivative according to any one of claims 1 -10 or the composition of claim 1 1 or 12.

15. A method for improving stability of an emulsion, suspension, dispersion, or foam system, said method comprising the step of including in the system the parenchymal cellulose

15 derivative according to any one of claims 1 -10 or the composition of claim 1 1 or 12.

16. A process for preparing an anionic parenchymal cellulose suspension, the process comprising: a. Providing parenchymal cellulose and optionally extracting it with an acid and/or an alkali;

20 b. recovering the cellulosic residue and optionally bleaching the cellulosic residue c. anionizing the cellulosic residue; d. harvesting the anionic cellulose as a suspension; and, optionally e. fibrillating the suspension from step d. wherein the fibrillation is carried out to provide improved yield stress compared to non-fibrillated suspension.

25 17. The process of claim 16 wherein bleaching is carried out in step b. and it comprises introducing aldehyde groups in the cellulosic residue; and anionizing in step c. comprises oxidizing at least partially the aldehyde groups formed in step b.

18. The process of claim 16 or 17 wherein in step b. aldehyde groups are introduced to at least 0.02 mmol/g, preferably 0.02-0.15mmol/g.

19. The process of claim 17 or 18 wherein aldehyde groups are introduced using hypochlorite and step c. comprises anionizing using an agent selected from chlorite, 5 sodium chlorite, chlorine dioxide, ozone, hydrogen peroxide, or a mixture thereof.

20. The process of claim any one of claims 16-19 wherein in step c. anionization is carried to an amount selected from the range between 0.05 and 0.2 mmol/g, preferably between 0.1 and 0.2 mmol/g, most preferably between 0.1 and 0.15 mmol/g.

21 . The process of claim 16 wherein anionizing is carried out using TEMPO oxidation.

10 22. The process of claim 21 wherein anionizing is carried out to 0.2-1 .5 mmol/g, preferably 0.3-1 .0 mmol/g, most preferably 0.3-0.8mmol/g.

23. The process of any one of claims 16-22 wherein the parenchymal cellulose is selected from a group comprising any of: sugar beet, bagasse, cassava and potato, the process optionally comprising bleaching the cellulosic material either before a. or after b., d., or e.

15 24. The process of any one of claims 16-23 further comprising concentrating the anionic parenchymal cellulose suspension.

25. An anionic parenchymal cellulose gel obtained by the process according to any one of claims 16-24.