Related Background Art In many industrial applications, it is important that thickening agents, or rheology modifying agents, possess the ability to form stable, highly viscous fluids on suspension or dissolution in solvents. The ability to form suspensions or solutions having good dispersibility is also important. High dispersibility promotes rapid development of viscosity and reduces the need to use mechanical dispersers, particularly where shear reduces the yield of the composition.

Reticulated bacterial cellulose is a useful and unique rheological modifying agent. As used herein, the term

"reticulated bacterial cellulose"refers to cellulose produced by microorganisms using aerobic culturing techniques and is characterized by a highly reticulated, branching interconnected network of fibers that are insoluble in water. Reticulated bacterial cellulose may be produced by the genus Acetobacter under agitated conditions and is available, under the registered trade name Cellulori, from the NutraSweet Kelco Company, a unit of the Monsanto Company, St.

Louis, Missouri.

The preparation of reticulated bacterial cellulose is well known. For example, U. S. Patent No. 5,079,162 and U. S. Patent No. 5,144,021, both of which are incorporated by reference herein, disclose a method and media for producing reticulated bacterial cellulose aerobically, under agitated culture conditions, using a bacterial strain of Acetobacter aceti var. xylinum. Use of agitated culture conditions results in sustained production, over an average of 70 hours, of at least 0.1 g/liter per hour of the desired cellulose. Wet cake reticulated cellulose, containing approximately 80-85% water, can be produced using the methods and conditions disclosed in the above-mentioned patents.

Dry reticulated bacterial cellulose can be produced by drying the wet-cake cellulose using drying techniques, such as spray-drying, drum-drying, tray-drying or freeze-drying, that are well known.

Acetobacter is characteristically a gram-negative, rod shaped bacterium 0.6-0.8ym by 1.0-4 ym. It is a strictly aerobic organism; that is, metabolism is respiratory, never fermentative. This bacterium is further distinguished by the ability to produce multiple poly fol-1,4-glucan chains, chemically identical to microcrystalline cellulose. These microfibrils generally have cross sectional dimensions of about 1.6

nm X 5.8 nm. Due to the small particle diameter, the microfibrils have a surface area several orders of magnitude higher than normal wood cellulose. It is this extremely high surface area that is responsible for many of the unique functional properties (viscosity, yield stress, binding properties etc.) of reticulated bacterial cellulose.

In order to efficiently use rheological modifying agents, it is preferable to use dried materials and to prepare the desired rheologically modified suspensions by re-hydrating the agents at the time of use.

However, when wet cake reticulated bacterial cellulose is dried to facilitate storage, the dry cellulose does not satisfactorily re-hydrate and re-disperse, even when subjected to homogenization or high shear mixing.

The process of drying the cellulose tends to promote inter-cellulose associations, resulting in a loss of surface area and hence, functionality of the cellulose.

Co-agents are commonly added to cellulose prior to drying to reduce the formation of the inter-cellulose associations. Additionally, high shear dispersion, or activation by mixing or homogenization, is used to thoroughly mix the cellulose and co-agent and to increase the cellulose surface area. Typically, processes for forming re-hydratable and re-dispersible cellulose compositions comprise using both co-agents and high shear activation. For example, Tiemstra (U. S.

Patent No. 3,573,058), Weibel (U. S. Patent No.

5,487,419), Herrick (U. S. Patent No. 4,481,076), and McGinley (U. S. Patent No. 4,263,334) disclose processes wherein microcrystalline cellulose is subjected to high shear mixing or homogenizing, then drying in the presence of co-agents, to prepare re-hydratable powders. The co-agents may also be added prior to the

homogenization of the cellulose to form intimate admixtures of the cellulose with the co-agent.

Brown, U. S. Patent No. 4,942,128, discloses an absorbent bacterial cellulose composition obtained by producing a bacterial cellulose in cell culture, in the presence of a polysaccharide derivative, preferably, carboxymethyl cellulose. The cellulose is collected and dried, by air drying or treatment with a non- aqueous hydrophilic solvent, to provide a water absorbent material. The resulting material is composed of cellulose, coated with carboxymethyl cellulose, having loosely bundled microfibrils in the form of ribbons.

A disadvantage of the above-described methods, however, is that the cellulose compositions produced can only be used in those commercial markets where the presence of the specific co-agent is either desirable or permissible. Thus, for different markets, different compositions containing different co-agents must be separately prepared.

Turbak, U. S. Patent No. 4,076,933, discloses a method for preparing a regenerated shaped cellulosic fiber that does involve the addition of co-agents. However, this method requires nitration of the cellulose prior to regeneration of the cellulose by use of alcohol solvents.

Battista, U. S. Patent No. 3,023,104, discloses the preparation of liquid absorbing cellulose aggregates that also do not contain added co-agents. The cellulose aggregates are prepared by acid hydrolysis of cellulose, followed by mechanical disintegration, preferably in water, and drying, preferably by spray drying, drum drying, freeze drying, or solvent

displacement using a water-miscible organic solvent, and more preferably by freeze drying.

However, as described above, when reticulated bacterial cellulose is dried from water, the dry cellulose does not readily re-hydrate or re-disperse. Accordingly, it would be highly desirable and economically important to develop a versatile reticulated bacterial cellulose material that may be readily re-hydrated and re- dispersed and may be post-blended with co-agents either prior to, simultaneously with, or subsequent to, re- dispersion to form stable, viscous cellulose compositions.

SUMMARY OF THE INVENTION A novel dry, re-hydratable and re-dispersible reticulated bacterial cellulose material, possessing exceptionally high surface area, is prepared by dispersing reticulated bacterial cellulose in an organic solvent, concentrating the dispersion to substantially remove the solvent from the dispersion, and drying. Optionally, the dried reticulated bacterial cellulose material may be subjected to grinding to provide the cellulose material in reduced particle sizes. Exemplary organic solvents useful in this invention include hydrocarbons, alkyl alcohols, alkyl sulfoxides, mixtures thereof or aqueous mixtures thereof.

The dry re-hydratable and re-dispersible reticulated bacterial cellulose material produced by this process may be advantageously re-dispersed in a re-dispersion solvent to form dispersions possessing excellent viscosity and yield stress. Preferably, at least one co-agent may be mixed with the reticulated bacterial cellulose material either prior to, simultaneously

with, or subsequent to, re-dispersion of the cellulose material in the re-dispersion solvent to form dispersions having superior stability and viscosity.

The reticulated bacterial cellulose material may be advantageously mixed with any of a variety of co-agents to prepare useful compositions for any of a variety of applications.

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a scanning photomicrograph of re-dispersed reticulated bacterial cellulose material, containing 0.017 wt% carboxymethyl cellulose and 0.1 wt% xanthan.

DETAILED DESCRIPTION OF THE INVENTION The re-hydratable and re-dispersible reticulated bacterial cellulose material of this invention is prepared by first dispersing reticulated bacterial cellulose in an organic solvent using high shear mixing, homogenization, attrition, milling or any other method capable of forming a uniform dispersion of the cellulose. The reticulated bacterial cellulose is preferably in wet cake form, containing approximately 10-20% cellulose and approximately 80-90% water. The dispersion generally contains about 0.1% to about 5% cellulose by weight, and preferably about 0.5% to about 3% cellulose by weight of the total weight of the dispersion.

Organic solvents that may be useful in preparing the reticulated bacterial cellulose dispersion include carbon-containing water-miscible solvents and carbon- containing non-water-miscible solvents, which when mixed with a carbon-containing water-miscible solvent form water-miscible solvent mixtures. These solvents may be used without dilution, but may also be used as a

solution mixture with other organic solvents or with water. Accordingly, the organic solvents useful in this invention include carbon-containing solvents, carbon-containing solvent mixtures and aqueous mixtures thereof. Exemplary organic solvents useful in the present invention include C5-CI2 hydrocarbons, C-C8 alkyl alcohols, C-C8 alkyl sulfoxides, mixtures thereof or aqueous mixtures thereof. The lower alkyl ketone solvent, acetone, which is highly water miscible, was found to be ineffective at providing a re-hydratable and re-dispersible reticulated bacterial cellulose material according to the present invention, and thus is not included within the scope of organic solvents as defined herein. Representative examples of suitable organic solvents include ethanol, isopropyl alcohol, methyl sulfoxide (dimethyl sulfoxide), butanol, methyl sulfoxide and isopropyl alcohol, hexane and isopropyl alcohol, methyl sulfoxide and water, hexane and methyl sulfoxide, and isopropyl alcohol and water.

Preferably, the organic solvent is isopropyl alcohol, methyl sulfoxide or a constant boiling mixture of isopropyl alcohol and water (approx. 82: 18). The dispersion contains the organic solvent in an amount from about 10% to about 99% by weight, and preferably in an amount of from about 65% to about 93% by weight of the total dispersion. The balance of the dispersion is generally water contained in the reticulated bacterial cellulose wet cake and/or added water.

According to the process of this invention, the reticulated bacterial cellulose/organic solvent dispersion is concentrated by filtration, centrifugation, pressing or the like, to substantially remove the solvent from the dispersion and to provide a wet cellulose material, generally in the form of a wet cake. The wet cellulose material is then dried by oven drying, spray drying, tray drying, drum drying or

freeze drying. The cellulose material is generally dried at temperatures of about-100°C to about 200°C.

The dried cellulose material may be optionally subjected to grinding, milling, blending or the like (hereinafter referred to as grinding), to reduce the size of the cellulose particles. The grinding process may be conducted at room temperature or at reduced temperatures, e. g., cryogenic milling. It is considered to be within the ordinary skill of those in the art to select a suitable grinding apparatus and/or grinding method to produce the cellulose material having a desired particle size.

Preferably, the cellulose material is dried using a multi-step process comprising alternating drying and grinding processes. The wet cellulose material may be partially dried to a solids content of about 10% to about 90% by weight, and preferably dried to a solids content of about 40% to about 80% by weight. The cellulose is partially dried in an oven at a temperature of about 50°C to about 110°C, and more preferably at a temperature of about 70°C to about 105°C. This partially dried cellulose material may optionally be subjected to grinding to form particulates of reduced particle size. Any conventional method of grinding may be used. The partially dried cellulose material may then be further dried to a solids content of about 90% to 100% by weight by drying at a temperature of about 50°C to about 110°C.

Advantageously, the dry reticulated bacterial cellulose material of this invention may be re-hydrated and re- dispersed to produce suspensions, or dispersions, possessing excellent viscosity and yield stress.

Generally, the cellulose material is re-dispersed in a re-dispersion solvent, using high shear or high

pressure extension conditions. Exemplary re-dispersion solvents include water, salt water, including heavy brines, C,-Cg alcohols, polyalcohols, such as polyethyleneglycol, glycerin, polypropylene glycol and the like, as well as base mixtures for various food products, such as ice cream, salad dressings, spoonable salad dressings and the like.

The amount of the reticulated bacterial cellulose material present in these re-hydrated reticulated bacterial cellulose material dispersions is generally an amount from about 0.05% to about 5% by weight, and preferably in an amount of from about 0.1% to about 1.5% by weight.

Preferably, at least one co-agent may be present in the reticulated bacterial cellulose material dispersion to form compositions having superior stability and viscosity. Co-agents that are useful in the present invention are polymeric compounds that function as processing aids to help to disperse the reticulated bacterial cellulose and to help stabilize the reticulated bacterial cellulose dispersions. The co- agents may be mixed with the cellulose material in any order, either prior to, simultaneously with, or subsequent to, re-dispersion of the cellulose material in solvent. The co-agents may be mixed in any form, as solids or liquids, or as an aqueous solution, with the cellulose material. A solution of co-agent may be formed by dissolving the co-agent in any suitable solvent. Exemplary co-agent solvents include water and Cl-C8 alkyl alcohols. If more than one co-agent is used, each co-agent may be added to the cellulose material separately or may be mixed together prior to addition to the cellulose material. Multiple co-agents may be added, either as a mixture or separately, in any order, either prior to, simultaneously with, or

subsequent to, re-dispersion of the cellulose material.

Preferably, the co-agent or co-agents are mixed with the dry cellulose material prior to re-dispersion to form a cellulose material/co-agent composition; the resulting composition may then be subjected to dispersion in a suitable re-dispersion solvent to form a composition dispersion.

Any of a variety of co-agents may be used in combination with the cellulose material, as may be required or desired for a specific application. One or more co-agents may be admixed with the cellulose material to provide compositions with desirable properties. Preferably, at least one co-agent is a polysaccharide, a heteropolysaccharide, or a saccharide. Exemplary co-agents and co-agent mixtures useful in the present invention include carboxymethyl cellulose, sucrose, xanthan gum, starch, corn syrups, inulin, carboxymethyl cellulose and sucrose, xanthan gum and carboxymethyl cellulose, and the like.

The quantity of co-agent or co-agents used in admixture with the re-hydratable and re-dispersible reticulated bacterial cellulose material will also vary as required or desired for a specific application. Generally, however, the concentration ratio of co-agent, or mixture of co-agents, to cellulose will range from about 1: 10 to about 1: 1.

The scanning photomicrograph (Figure 1) of re-dispersed reticulated bacterial cellulose material, with 0.017% carboxymethyl cellulose and 0.1% xanthan, shows that uniform, fine cellulose fibers, possessing an exceptionally high surface area, may be produced by the process of this invention.

The Examples which follow are intended as an illustration of certain preferred embodiments of the invention, and no limitation of the invention is implied. In each of the following Examples, the viscosity and yield stress of the dispersions containing re-hydrated reticulated bacterial cellulose material were measured at room temperature using a Brookfield DV-III Viscometer (Brookfield Engineering Laboratories, Inc., Stoughton, Massachusetts).

Example 1 Reticulated bacterial cellulose wet cake (100 g, 10 wt% solids) and isopropyl alcohol (400 g, 99%) were homogenized using an Osterizer mixer (manufactured by Osterizer, Incorporated, Mexico) for 2 minutes. The resulting slurry, containing approximately 2 wt% cellulose, was vacuum filtered using a Buchner funnel with a membrane filter (membrane pore size <500 microns) for 12 minutes. The filtered cellulose material (62.2 g) contained 16.1 wt% cellulose. The wet reticulated bacterial cellulose material was dried in an oven at 105°C with ventilation for 50 minutes to provide 9.2 g of flakes of the reticulated bacterial cellulose material. The dry flakes were subjected to grinding for 40 seconds to form coarse particles.

The reticulated bacterial cellulose material particles were re-dispersed together with xanthan gum (Keltrol*, sold by the NutraSweet Kelco Company, San Diego, California) by homogenization for 4 minutes, in a 1 wt% aqueous sodium chloride (NaCl) solution to provide a dispersion containing 0.2 wt% cellulose and 0.1 wt% xanthan. The viscosity and yield stress of the resulting dispersion were 842 cP and 9.1 dynes/cm2, respectively, at room temperature.

Example 2 Reticulated bacterial cellulose wet cake (87 g, wet cake, 13.8 wt% solids) and isopropyl alcohol (1113 g, 99%) were homogenized using an Osterizer mixer for 3 minutes. The resulting slurry, containing approximately 1 wt% cellulose, was vacuum-filtered to give 171 g wet cake reticulated bacterial cellulose material (approx. 7 wt% cellulose). The cake was dried in an oven at 70°C with ventilation for about two hours, to provide 12.5 g of solids. The dry flakes were subjected to grinding for one minute to obtain coarse particles.

The dry reticulated bacterial cellulose material was combined with xanthan gum (Keltrol) and carboxymethyl cellulose, hereinafter,"CMC" (9M sold by Aqualon, Newark, Delaware) and re-dispersed in prepared tap water using a Waring Blender. Prepared tap water is a solution composed of 20 g sodium chloride and 2.94 g calcium chloride dihydrate in 20 liters distilled water. The resulting dispersion of reticulated bacterial cellulose (0.2 wt%) with post-added xanthan gum (0.1 wt%) and CMC (0.017 wt%) possessed high viscosity (1278 cP) and very high yield stress (24.2 dynes/cm2), at room temperature.

Example 3 Reticulated bacterial cellulose wet cake (37.3 g, 16.1 wt% solids) and isopropyl alcohol (563 g, 99%) were homogenized using an Osterizer mixer for 4 minutes.

The resulting slurry, containing approximately 1 wt% cellulose, was vacuum-filtered to give 63 g wet cake reticulated bacterial cellulose material (approx. 9.5 wt % cellulose). The cake was dried in an oven at ambient temperature with ventilation for about 70

minutes, then at 70°C for 30 minutes, to provide 6.0 g of solids. The dry flakes were subjected to grinding for one minute to provide coarse particles.

The dry reticulated bacterial cellulose material was combined with xanthan gum and CMC (9M) and re-dispersed in prepared tap water using a Waring Blender. The resulting dispersion of reticulated bacterial cellulose material (0.2 wt%) with xanthan (0.1 wt%) and CMC (0.017 wt%) had a viscosity of 1163 cP and yield stress of 10.3 dynes/cm2 at room temperature.

Example 4 Reticulated bacterial cellulose wet cake (37.3 g, 16.1 wt% solids) and 563 g of a solution of 82 wt% isopropyl alcohol in water were homogenized using an Osterizer mixer for 4 minutes. The resulting slurry (approximately 10.0 wt% cellulose) was vacuum-filtered to give 60 g wet cake reticulated bacterial cellulose material (approx. 10.0 wt% cellulose). The cake was dried in an oven at ambient temperature with ventilation for about 70 minutes, then at 70°C for 30 minutes to provide 6.0 g of solids. The dry flakes were subjected to grinding for one minute to provide coarse particles.

The dry reticulated bacterial cellulose material, xanthan and CMC (9M) were re-dispersed in prepared tap water using a Waring Blender. The dispersion of the reticulated bacterial cellulose material (0.2 wt%) with post-added xanthan (0.1 wt%) and CMC (0.017 wt%) had a viscosity of 870 cP and yield stress of 4.62 dynes/cm2 at room temperature.

Example 5 Reticulated bacterial cellulose wet cake (43.5 g, 13.8 wt% solids) and isopropyl alcohol (566.5 g, 99%) were homogenized using an Osterizer mixer for 5 minutes.

The resulting slurry, containing approximately 1 wt% cellulose, was vacuum-filtered to give 49.4 g wet cake reticulated bacterial cellulose material (approx. 12.1 wt% cellulose). The cake was dried in an oven at 100°C with ventilation for 30 minutes to provide 6.0 g of solids. The dry flakes were subjected to grinding for one minute to provide coarse particles.

The dry reticulated bacterial cellulose material, xanthan and CMC (9M) were re-dispersed in prepared tap water using a Waring Blender. The dispersion of the reticulated bacterial cellulose material (0.2 wt%) with post-added xanthan (0.1 wt%) and CMC (0.017 wt%) had a viscosity of more than 1200 cP and yield stress of more than 16 dynes/cm2 at room temperature.

Example 6 Reticulated bacterial cellulose wet cake (43.5 g, 13.8 wt% solids) and 556.5 g of a solution of 82 wt% of isopropyl alcohol in water were homogenized using an Osterizer mixer 5 minutes. The resulting slurry, containing approximately 1 wt% cellulose was vacuum- filtered to give 46.7 g wet cake reticulated bacterial cellulose material (approx. 12.8 wt% cellulose). The cake was dried in an oven at 100°C with ventilation for 30 minutes to provide 6.0 g of solids. The dry flakes were subjected to grinding for one minute to provide coarse particles.

The dry reticulated bacterial cellulose material, xanthan and CMC (9M) were re-dispersed in prepared tap

water using a Waring Blender. The dispersion of the reticulated bacterial cellulose material (0.2 wt%) with post-added xanthan (0.1 wt%) and CMC (0. 017 wt%) had viscosity and yield stress of more than 1200 cP and 15.5 dynes/cm2, respectively, at room temperature.

Example 7 Reticulated bacterial cellulose wet cake (43.5 g, 13.8 wt% solids) and isopropyl alcohol (556.5 g, 99%) were homogenized using an Osterizer mixer for 5 minutes.

The resulting slurry, containing approximately 1 wt% cellulose, was vacuum-filtered to give 60.8 g wet cake reticulated bacterial cellulose material (approx. 9.9 wt% cellulose). The cake was dried in an oven at 80°C with ventilation for 30 minutes to provide 6.41 g of solids. The dry flakes were subjected to grinding for one minute to provide coarse particles.

The dry reticulated bacterial cellulose material, CMC (9M) and sucrose were re-dispersed in prepared tap water using a Waring Blender. The resulting dispersion containing the reticulated bacterial cellulose material (0.2 wt%) with post-added CMC (0.067 wt%) and sucrose (0.067 wt%) had a viscosity and yield stress of more than 695 cP and 3.95 dynes/cm2 at room temperature.

Example 8 Reticulated bacterial cellulose wet cake (43.5 g, 13.8 wt% solids) and 556.5 g of a solution of 82 wt% of isopropyl alcohol in water were homogenized using an Osterizer mixer for 5 minutes. The resulting slurry, containing approximately 1 wt% cellulose, was vacuum- filtered to give 43.8 g wet cake reticulated bacterial cellulose material (approx. 13.7 wt% cellulose). The cake was dried in an oven at 80°C with ventilation for

30 minutes to provide 6.0 g of solids. The dry flakes were subjected to grinding for one minute to provide coarse particles.

The dry reticulated bacterial cellulose material, CMC (9M) and sucrose were re-dispersed in prepared tap water using a Waring Blender. The dispersion of the reticulated bacterial cellulose material (0.2 wt%) with post-added CMC (0.067 wt%) and sucrose (0.067 wt%) had viscosity and yield stress of more than 657 cP and 3.54 dynes/cm2, respectively, at room temperature.

Example 9 Reticulated bacterial cellulose wet cake (43.5 g, 13.8 wt% solids) and isopropyl alcohol (556.5 g, 99 wt%) were homogenized using an Osterizer mixer for 4 minutes. This process was repeated for 16 times to obtain a total slurry of 9600 grams. The resulting slurry, containing approximately 1 wt% cellulose, was vacuum-filtered to provide a thick wet cake (approx. 10 wt% solids). The cake was dried in an oven at 75°C with ventilation for one hour. The partially dried reticulated bacterial cellulose material had a solids content of approximately 77 wt%. The partially dried cellulose material was divided into portions.

One portion of the partially dried cellulose was subjected to grinding for one minute to provide coarse particles. This partially dried ground cellulose material was fully dried at 100°C for 20 minutes in an oven and used to prepare a series of test compositions.

The dried reticulated bacterial cellulose material, CMC (9M) and sucrose were re-dispersed in prepared tap water using a Waring Blender. The aqueous dispersion of the reticulated bacterial cellulose material (0.2 wt%), CMC (0.067 wt%) and sucrose (0.067 wt%) possessed

a viscosity and yield stress of 759 cP and 5.42 dynes/cm2, respectively, at room temperature. The dried reticulated bacterial cellulose material (0.35 wt%) was also re-dispersed in 13.5 lbs/gal CaCl2/CaBr2 heavy brine to form a dispersion having a dynamic viscosity and yield stress of 9814 cP and 34.0 dynes/cm2, respectively, at room temperature.

Another portion of the partially dried cellulose material was cryogenically milled to 20 mesh size fine particles. When this cryogenically-milled reticulated bacterial cellulose material (1.0 wt%) was re-dispersed in glycerin (99%), the viscosity of the resulting dispersion was as high as 580,000 cP, at room temperature.

Example 10 Reticulated bacterial cellulose wet cake (44 g, 13.8% solids) and dimethyl sulfoxide (554 g) were homogenized for 4 minutes and then vacuum filtered to give a wet cake of 57.8 g reticulated bacterial cellulose material (approximately 10 wt% cellulose). The wet cake was broken into smaller pieces and placed in a ventilated dryer for 1 hour at 85°C. This cellulose material was subjected to grinding for one minute to provide smaller particles and then placed in the oven for 1 hour at 100°C.

The dry reticulated bacterial cellulose material was re-dispersed in prepared tap water (0.2 wt% cellulose) with post-added CMC (9M, 0.067 wt%) and sucrose (0.067 wt%). The viscosity and yield stress of the dispersion was 704 cP and 5.6 dynes/cm2, at room temperature.

Example 11 Reticulated bacterial cellulose wet cake (44 g, 13.8% solids), dimethyl sulfoxide (272 g) and isopropyl alcohol (272 g) were homogenized for 4 minutes and vacuum filtered to give a wet cake of 49.4 g (approximately 12 wt% cellulose). The wet cake was broken into smaller pieces and dried in a ventilated dryer for 1 hour at 85°C. The material was subjected to grinding in a Osterizer mixer for 1 minute and then dried in the oven for 1 hour at 100°C.

The dry reticulated bacterial cellulose material was re-dispersed in prepared tap water (0.2 wt% cellulose) with post-added CMC (9M, 0.067 wt%) and sucrose (0.067 wt%). The viscosity and yield stress of the dispersion was 853 cP and 6.8 dynes/cm2, at room temperature.

Example 12 Reticulated bacterial cellulose wet cake (44 g, 13. 8% solids), hexane (55 g) and isopropyl alcohol (489 g) were homogenized for 4 minutes and then vacuum filtered to give a wet cake of 39.1 g (approximately 15 wt% cellulose). The wet cake was broken into smaller pieces and dried in a ventilated dryer for 1 hour at 85°C and then cryogenically milled to 20 mesh sized particles.

The dry reticulated bacterial cellulose material was re-dispersed in prepared tap water (0.2 wt% cellulose) with post-added CMC (9M, 0.067 wt%) and sucrose (0.067 wt%). The viscosity and yield stress of the dispersion was 870 cP and 6.2 dynes/cm2, at room temperature.

Example 13 Reticulated bacterial cellulose wet cake (43.6 g, 13.8 wt% solids) and isopropyl alcohol (524 g, 99%) were homogenized using an Osterizer mixer for 5 minutes.

The resulting slurry, containing approximately 1 wt% cellulose, was vacuum-filtered to give 43 g wet cake reticulated bacterial cellulose material (approx. 14 wt% cellulose). The cake was freeze-dried at-60°C and 100 milli Torr (0.1 Torr) for 3 hours. The dry flakes were subjected to grinding for 30 seconds to provide coarse particles.

The dry reticulated bacterial cellulose material and CMC (9M) were re-dispersed in prepared tap water using a Waring Blender. The resulting dispersion of reticulated bacterial cellulose material (0.2 wt%) and CMC (0.067 wt%) had viscosity and yield stress of 896 cP and 6.7 dynes/cm, respectively, at room temperature.

Other variations or modifications, which will be obvious to those skilled in the art, are within the scope and teachings of this invention. This invention is not to be limited except as set forth in the following claims.