MXPA99011617A - Ultra-fine microcrystalline cellulose compositions and process for their manufacture - Google Patents

Abstract

Se describen composiciones de celulosa microcristalina ultrafina que producen suspensiones y/o dispersiones altamente estables en las que sustancialmente toda la celulosa microcristalina tiene un tamaño de partícula no mayor que aproximadamente 0.7æ;las composiciones incluyen auxiliares de desgaste que tienen una doble funcionalidad, ayudando a reducir el tamaño de los microcristales de celulosa y agregando una propiedad o ingrediente deseado a las dispersiones u otros productos en los que se utilizan las composiciones.

Description

COMPOSITIONS OF ULTRAFINE ALINA MICROCRIST CELLULOSE AND PROCEDURE FOR ITS MANUFACTURE FIELD OF THE INVENTION The present invention relates to ultrafine microcrystalline cellulose, compositions thereof, to a process for their manufacture, and to certain products containing the same. More particularly, the invention relates to microcrystalline cellulose compositions in particles that can be dispersed to form suspensions, or they can be dried and the resulting particulate solid dispersed in a liquid medium to produce a suspension. In suspensions, substantially all microcrystalline cellulose particles are sub-micron in size and remain in a colloidal state even when centrifuged. This invention also relates to suspensions made of ultrafine microcrystalline cellulose of this invention.

BACKGROUND OF THE INVENTION Microcrystalline cellulose is a purified, partially depolymerized cellulose which is produced by treating a source of cellulose, preferably alpha-cellulose in the form of pulp of fibrous plant materials, with a mineral acid, preferably hydrochloric acid. The acid selectively attacks the less ordered regions of the cellulose polymer chain by exposing and thus releasing the crystalline aggregate crystallite aggregates constituting the microcrystalline cellulose. Subsequently these are separated from the reaction mixture, and washed to remove degraded by-products. The resulting moist mass, which generally contains 40 to 60% moisture, is mentioned in the art by various names, including hydrolyzed cellulose, hydrolyzed wet cake, leveled DP cellulose, wet microcrystalline cellulose cake or simply wet cake. When the wet cake is dried and freed of water, the resulting product, microcrystalline cellulose, is white, odorless, tasteless, relatively free-flowing powder, soluble in water, organic solvents, acids and diluted alkalis. For a further description of the microcrystalline cellulose and its manufacture, see the patent of E.U.A. No. 2,978 446. The patent discloses its use as a pharmaceutical excipient, particularly as a binder, disintegrator, flow aid, and / or filler for the preparation of compressed pharmaceutical tablets. Microcrystalline cellulose is manufactured by FMC Corporation and sold under the name Avicel® PH, cellulose in various grades having average particle sizes ranging from about 20 μ to about 100 μ. The microcrystalline cellulose and / or wet hydrolyzed cellulose cake has been modified for other uses, especially for use as a gelling agent for food products, a thickener for food products, a fat substitute and / or non-caloric filler for various food products, as a suspension stabilizer and / or texturizer for food products, and as an emulsion stabilizer and suspending agent in pharmaceutical and cosmetic lotions and creams. The modification for such uses is carried out by subjecting the microcrystalline cellulose or wet cake to internal wear forces as a result of which the crystallites are substantially subdivided to produce finely divided particles. However, although the particle size is decreased, individual particles tend to agglomerate or harden upon drying, probably due to hydrogen or other bonding forces between the smaller particles. To prevent agglomeration or hardening, a protective colloid, such as sodium carboxymethylcellulose (CMC), can be added, which neutralizes all or part of the binding forces that cause agglomeration or hardening, during wear or after wear but before drying . This additive also facilitates the re-dispersion of the material after drying. The resulting material is often referred to as worn microcrystalline cellulose or colloidal microcrystalline cellulose. For a more complete description of colloidal microcrystalline cellulose, its manufacture and uses, see U.S. Pat. No. 3,359,365, wherein it is stated that at least 1% and preferably at least 30% of the microcrystalline cellulose has been reduced to a particle size not exceeding about 1.0 micron.

Colloidal microcrystalline cellulose is an odorless, hygroscopic white powder. When dispersed in water, it forms opaque thixotropic gels, and white. It is manufactured and sold by FMC Corporation (FMC) in various grades under the names, among others, Avicel® RC and Avicel® CL, which comprise co-processed microcrystalline cellulose and sodium carboxymethylcellulose. In the FMC RC-16 product bulletin, grades designated as RC-501, RC-581, RC-591, and CL-611 are described as dispersion producers in which approximately 60% of the particles in the dispersion are less than 0.2 micras when dispersed properly. With great interest in the use of finely divided cellulose materials in pharmaceutical and food suspensions, researchers in the field have focused a significant amount of attention to improve the smoothness and palatability of suspensions made of cellulose materials, and have determined, for example, that the cellulose particles having a particle size above about 3 μm perceive the tongue as a particulate material or granulate. Komuro, in European Patent Publication No. 0 415 193 A2 teaches that it is necessary to avoid feeling to provide a material in which 50% cumulative volume of the cellulose particles have a particle size on the scale of 0.3 μ. at 6.0 μ when at least 25% of the cumulative volume in the suspension has a particle size not greater than 3 μ. The patent also teaches a method for milling and an apparatus employing a high-speed rotary mill to wet-grind the cellulose material using ceramic or metallic spheres as a grinding medium to achieve these objectives. This and another patent related to Komuro et al., Patent of E.U.A. No. 5,123,962, but in particular the latter, have a broad description of the unsuccessful efforts made in the art to further reduce the particle size of microcrystalline cellulose. Also, the patent of E.U.A. No. 5,415,804, teaches that a soft sensation to the palate depends on the colloidal fraction as well as the distribution of the particle size and average particle size, the colloidal fraction being that fraction of the dispersed particles that can not be precipitated by the centrifugation of the dispersion. Depending on the particle size distribution (which is somewhat broader than that of the Komuro patent, mentioned above, being as high as 10 μ), the colloidal fraction must be on the scale of 50% to 65% of the volume cumulative. In this patent, however, certain water-soluble gums and / or hydrophilic materials are used to compensate for the larger scale of the size distribution.

BRIEF DESCRIPTION OF THE INVENTION In accordance with the present invention, a method has been found for reducing the particle size of microcrystalline cellulose and for forming microcrystalline cellulose compositions having an extremely high percentage (in some cases as high as 100%) of microcrystalline cellulose having a particle size consistently less than 1 miera, which, when dispersed in a liquid medium, will not precipitate out of the dispersion and may not be physically removed or precipitated by centrifugation below about 15,000 rpm. For purposes of this invention, that concept will be referred to hereafter as "colloidally stable". In the process of the invention, the moist hydrolyzed cellulose cake is wet milled with a wear aid under high shear high solid mixing conditions and optionally with a protective colloid to form the microcrystalline cellulose compositions of this invention. The wear aid that facilitates the wet milling of the microcrystalline cellulose can remain in the product and will preferably contribute a desired property or component to the finished product in which the microcrystalline cellulose is used. As an example of this double functionality, calcium carbonate, or other suitable calcium salts can be used as wear aids for microcrystalline cellulose compositions used to prepare calcium fortified milk products. It is also contemplated that the wear aid may, itself, or at least a greater portion thereof, be suspended in the colloidal microcrystalline cellulose dispersions in which the compositions of this invention are used.

The process can also employ a protective colloid which prevents hardening of the microcrystalline cellulose and also facilitates redispersion of dry microcrystalline cellulose compositions. However, in certain microcrystalline cellulose compositions that were used as fillers or volume adjuncts, the protective colloid may be omitted to promote the formation of a reduced, less porous, densified absorbent form of microcrystalline cellulose. The composition of this invention may be the wet-weathered microcrystalline solid recovered from the milling process; or it may be the dry residue thereof, prepared by removing the moisture from the wet solid, the latter being preferred for storage, shipping and subsequent use for the preparation of microcrystalline cellulose dispersions. The dispersions in which the microcrystalline cellulose compositions of the present are used have excellent suspension and stabilization properties and require less microcrystalline cellulose (on a weight basis) to achieve stabilization and / or suspension properties equal to or greater than those which they are achieved only with high levels of existing microcrystalline cellulose products. Dispersions made from the compositions of this invention contain microcrystalline cellulose ultrafine submicron size particles which are virtually colloidally stable, as defined above, and thus can provide improved suspension / stabilization.

DETAILED DESCRIPTION OF THE INVENTION The present invention uses as the starting material the moist cake of hydrolyzed cellulose described above, which is the undried dough produced when a source of cellulose, preferably alpha-cellulose in pulp form of fibrous vegetable materials, is treated with a mineral acid and subsequently washed to remove the acid and by-products, producing a wet cake that generally contains from about 40 to about 60% moisture. In accordance with the present invention, a wear aid is mixed with the wet cake. Optionally a protective colloid is added, particularly if it is contemplated that the composition will be dried, stored or sent in a dry and dispersed form to obtain colloidally stable dispersions. These starting ingredients can be subsequently mixed in the usual manner. In the preparation of the wet mix, the moisture content can be adjusted as desired to produce the desired consistency for the wear of the mix and adjusted as needed during wear to maintain the desired consistency. In a preferred embodiment, the moisture present in the wet cake is generally sufficient. The use of excess water should be avoided as this will tend to reduce the particle to particle abrasion forces that are necessary to reduce the microcrystalline cellulose particles to a consistent sub-micron size. Subsequently, the wet mixture is preferably weathered as a wet mixture with high solids content under high shear high solid mixing conditions, in which the wear aids grind or facilitate grinding of the microcrystalline cellulose into sub-size particles. - ultrafine microns that are colloidally stable in dispersion. In a preferred embodiment, colloidal stability is further facilitated by the inclusion of a protective colloid. The wear aid, as indicated above, is preferably selected as a multi-functional component of the mixture. That is, it has the function of grinding the microcrystalline cellulose and also have the additional function of contributing a desired composition or property to the product in which the microcrystalline cellulose composition of this invention is used. Thus, when selecting a wear aid, it is preferred that the selection be made with due consideration to both objectives. In relation to its function when grinding microcrystalline cellulose to an ultrafine particle size, the wear aid must be relatively insoluble to water; that is, sufficiently insoluble so that it does not dissolve considerably when mixed with the moist cake of hydrolyzed cellulose. More particularly, the wear aids useful in the present invention may be ionic materials having a Ksp equal to or less than 1x10"7 or powdered materials or granulates having a solubility in water equal to or less than 40% at 100 ° C. It must be a relatively thin material, so that it is placed in close grinding contact with the particles of the wet cake during wear, but not necessarily colloidal in size, so that, for example, its particle size can be found in the scale of about 0.1 microns to about 100 microns in a usable manner in the range of about 0.1 to about 20 μ and preferably is less than about 10 μ. Agents that have been shown to be suitable ionic materials include limestone (carbonate calcium), dicalcium phosphate, tricalcium phosphate, zinc carbonate, zinc hydroxide, magnesium phosphate, barium carbonate, barium sulfate, ferrous carbonate or, aluminum hydroxide, magnesium hydroxide, and magnesium aluminum hydroxide. Other materials useful as wear aids include nonionic materials such as silica, various clays, silicates, silicon dioxide, talc, titanium dioxide, and certain plastic resins, as well as partially soluble organic materials, for example lactose and the like. In fact, it is believed that many materials are suitable for this purpose, and it is contemplated that these wear aids may be used alone or in combination to achieve the desired properties. In addition to their function to grind cellulose, the wear aids of this invention preferably remain as a component of the dispersions formed from the microcrystalline cellulose compositions of this invention, and contribute desired ingredients, components or properties to said final products. As indicated above, calcium carbonate is used in a beneficial manner to fortify calcium values in milk or milk products or to coat paper and perform other functions in papermaking processes; the magnesium and / or aluminum hydroxides may be pharmaceutical preparations of useful additives such as antacids; and titanium dioxide containing compositions is useful in paints and pigments in coffee creamers and other products. The wearing agents of this invention can advantageously be abrasive, relatively insoluble components that are used in applications and pharmaceuticals, for personal hygiene and cosmetics, such as lotions, ointments, gels, and pastes, including for example toothpastes and other products for dental care. For toothpastes, preferred wear agents include calcium carbonate, dicalcium phosphate and silica which are known abrasives in toothpastes. For most applications, it is preferred that the mixture contain a protective colloid. When present, these protective colloids can perform one or more functions. They act as a barrier between and / or around the microcrystalline cellulose particles, probably by binding to, or replacing the hydrogen bonding forces between, and thus forming a barrier between said particles to prevent them from hardening. Subsequently they act as dispersion aids to facilitate the dispersion and rehydration of the microcrystalline cellulose particles when the dried solid microcrystalline cellulose compositions are dispersed again. In addition, they can help to suspend and / or alter the rheological properties of the suspension. It is believed that numerous agents will have similar functions for example, cellulose derivatives such as carboxymethylcellulose, hydroxypropylcellulose, hydroxypropylmethylcellulose and hydroxyethylcellulose. Various gums such as guar gum, carob, gum arabic, gum tragacanth and karaya gum, as well as seaweed extracts such as carrageenan and algin, and starches such as maltodextrin, hydrolyzed cereal solids, and pectin may also be useful. A preferred agent for this purpose is sodium carboxymethylcellulose (CMC). For other applications for example, when it is desired to use the compositions as fillers or bulking agents, it is preferred to have a densifying, relatively non-porous product having low water and oil absorption capacity. For these applications, the microcrystalline cellulose and the wear agent can be used without the inclusion of a protective colloid. Upon drying, the product will subsequently agglomerate into a less porous and denser material than could have been obtained with earlier products that had less uniform and larger microcrystalline cellulose particles. These fillers or bulking agents will be less absorbent (water or oil) and may be useful in applications with low humidity, for example low moisture foods such as sandwich cookies, chocolate, peanut butter, and the like. The reduction of microcrystalline cellulose to the colloidal particle size is preferably carried out by high-shear high-shear wet milling of the microcrystalline cellulose mixture, wear aids, and preferably a protective colloid. The use of a standard extruder, preferably with multiple screws, is a preferred means for reducing the particle size of microcrystalline cellulose. Other standard equipment can also be used for high shear wet milling operations, such as planetary mixers, for example Hobart mixers, ball mills, friction wear mills and roller mills, particularly those having two or more rollers. It is important that the equipment used provides a high shear action and provides intense friction, abrasive action between the microcrystalline cellulose and the wear aid, for example by forcing the mixture through passages of limited cross section such as those found in perforated plates of extruders and other mixing equipment, or other spaces of limited space such as those found between the rollers of the cylinder mills. The extrusion process is preferred for its ease of operation in high production and high solids processing and for its efficiency in producing very fine particles of microcrystalline cellulose.

In the process of the invention, the first step consists of mixing unspent microcrystalline cellulose, a wear agent and optionally a protective colloid. The solids content represented by the microcrystalline cellulose and the wear agent is suitable in the range from about 30% to about 80% by weight of the mixture, preferably from about 40% to about 60%. The weight ratio of the microcrystalline cellulose to the wear agent is suitable in the range of about 85:15 to about 30:70, usable in the range of about 70:30 to about 40:60. When a protective colloid is used, it is suitably used in an amount on the scale of 5% to 30% by weight, preferably 5% to 15%, of the microcrystalline cellulose; that is, the weight ratio of microcrystalline cellulose to protective colloid is on the scale of about 95: 5 to about 70:30. The mixing is continued until a uniform wet mix is obtained. Subsequently, the wet mix is subjected to high shear wet milling for a time and under shear forces sufficient to reduce the microcrystalline cellulose to a particle size in which about 80% to 100%, in a usable manner of about 90% to 100%, microcrystalline cellulose has a particle size no greater than 1 μ and is colloidally stable when dispersed in an aqueous medium. None of the larger particles will have a particle size below about 3-4 μ, so the resulting mixture will be virtually free of particles, which may be perceived with a sandy palate sensation or grainy by the tongue and tongue. mouth. However, preferably, about 100% of the microcrystalline cellulose has a particle size less than 1 miera, and at least 90% to 95% has a particle size less than 0.75 μ. As shown in the examples, the particle size distribution of the microcrystalline cellulose appears to be in the range of about 0.1 to about 0.7 μ in the microcrystalline cellulose dispersions that were produced in accordance with this invention. The particle size of the wear aid is generally not appreciably reduced when an extruded mixture contains a wear aid whose particles are harder than those of the microcrystalline cellulose. For example, the fact of extruding a mixture comprising calcium carbonate having an average particle size of many microns can provide a dispersion having submicron particles of microcrystalline cellulose with calcium carbonate particles of several microns. In this way, it is possible to provide dispersions where the microcrystalline cellulose is sub-micron and the auxiliary wear is larger. The wet weathered microcrystalline cellulose composition resulting from an extrusion or other suitable process can be recovered and subsequently dispersed as a stabilizing / suspending agent for the suspension and dispersions and / or can further be processed, dried, subsequently dispersed for such uses. The additional processing step, if used, can include the preparation of an initial dispersion, homogenizing the resulting dispersion, drying it, for example, by spray drying or other suitable means, which are within the scope of the art and they illustrate in the examples presented below. Depending on the starting ingredients and the ratios in which they are employed, the compositions of this invention thus comprise an ultrafine weathered microcrystalline cellulose composition comprising microcrystalline cellulose particles having a particle size as described above, optionally a auxiliary wear as defined above, and optionally a protective colloid, wherein the weight ratio of the microcrystalline cellulose to the wear aid is in the range of about 85:15 to about 30:70, usable from about 70:30 to about 40:60 and, when a protective colloid is used, the weight ratio of microcrystalline cellulose to protective colloid is on the scale of about 95: 5 to about 70:30. The ultrafine colloidally stable microcrystalline cellulose of this invention or the product of this invention of microcrystalline cellulose, wear agent and optional protective colloid is used in dispersions, emulsions, suspensions and the like in an amount of about 0.05-15% by weight, advantageously 0.05 to 5% by weight, preferably about 0.05-3% by weight, and used as a filler or bulking agent, in an amount of about 1-25% by weight, based on the final product . For food applications, 0.05-15% by weight can be used appropriately. Those skilled in the art will appreciate that the compositions of this invention have many and diverse applications in food, pharmaceutical, and personal care products, such as cosmetic creams and lotions and dental care products, such as toothpaste formulations. , as well as numerous medical and industrial applications, wherever and whenever a more effective suspension stabilizer or a soft creamy filler or dispersion aid is required. In this way, the products are particularly suitable for the fortification of calcium, texturization and stabilization of milk products, nutritional products in suspension, vitamin and mineral supplements, for suspensions of organic molecules insoluble in water, and for various applications such as stabilization of other food, pharmaceutical, dental and cosmetic formulations, paints, and numerous industrial applications such as suspension opacifiers in the papermaking process, and paper coating with calcium carbonate. The following examples illustrate only some of the potential uses for the compositions of this invention, and are not intended to limit the scope of the applications for which the invention is useful. Unless indicated otherwise, all percentages in the examples are by weight.

However, these examples also illustrate that, when using the products of this invention in finished products, one must take into account different and various formulation factors that influence and / or determine the nature and quality of the product to be prepared. The composition of this invention should be used at the appropriate level and concentration for each product. The specific properties of each product or formulation can be affected by other factors such as the specific wear agent selected for a particular formulation, other additives that are included in the formulation, etc. As examples of such considerations in terms of design and formulation, Example 9 illustrates that, although calcium values are highly desirable as calcium supplements for certain food and pharmaceutical products, the use of a highly soluble calcium salt such as sulfate Calcium does not produce a microcrystalline cellulose composition that disperses well in aqueous media, but tends to cause microcrystalline cellulose flocculation for reasons that are not fully understood. Similarly, although Example 17 illustrates the preparation of a refined void suspension, the inclusion of sucrose produces a slurry that can not be resuspended with the addition of water. Similarly, Example 18 illustrates the ability to make a stable pharmaceutical preparation that is dosed with a spoon having the consistency and appearance of whipped cream or other food products, pharmaceuticals and whipped cosmetics.

EXAMPLE 1 237.5 grams of ground limestone (K5p = 3.36x10"9), 552.3 grams of moist hydrolyzed cellulose cake, and 26.9 grams of medium viscosity carboxymethylcellulose were placed in a Hobart mixing bowl.The ratio of solids comprising this mixture was of 47.5 parts of cellulose, 47.5 parts of calcium carbonate, and 5 parts of carboxymethylcellulose The mixer was operated until the composition became uniform, then the composition was transferred to a twin screw extruder which was operated at 150 rpm with the Exit door fixed at 6.35 mm for the first step and 19.5 mm for the second to the fourth step The dispersions of this product in wet having 1% and 2% solids were prepared in water The 1% dispersion became a gel When examined using a microscope, the cellulose particles appeared extremely fine and uniform in size.The dispersion at 2% was established in a strong gel. the remaining was dispersed in water with 5% solids and homogenized at 17.236.9 kPa. The viscosity of this dispersion after homogenization was 8700 cps. Subsequently, the dispersion was spray-dried at an inlet temperature of 190-200 ° C and an outlet temperature of 100 ° C. In a Waring blender, a dispersion of 8 grams of the resulting powder was prepared in 392 grams of water. Initially, the viscosity when measured with a Brookfield RVT viscometer using spindle # 1 at 10 rpm for 1 minute was 615 cps. The dispersion of this powder had the same stability as the dispersions of the wet composition after wear. Additional dispersions of the spray-dried powder were prepared with 1%, 0.75% and 0.5% solids. There was no sedimentation at 1% and the system gelled. At 0.75% there was only a slight sedimentation. The system formed a weak gel and estimated as stable. At 0.5% the sedimentation of the dispersion remained light and the system slightly gelled.

EXAMPLE 2 Additional compositions were prepared while varying the ratio of the solid components significantly. The procedure described in example 1 was followed exactly. In the chart, the composition that was worn is shown, including the solids ratio.

TABLE 1 Example Composition Solids ratio CaCO3 cake (g) wet CMCD (g) 2A 576.9 225.0 53.8C 45/45/10 2B 865.4 125.0 40.3d 67.5 / 25 / 7.5 2C 718.0 488.0 34.4d 35/61/4 2D 980.8 75.0 45.7d 76.5 / 15 / 8.5 a moist cake of hydrolyzed cellulose carboxymethylcellulose c26.9 grams of carboxymethylcellulose of low viscosity and medium viscosity. d carboxymethylcellulose of medium viscosity The product of those examples, when dispersed in water with 1% solids, produced stable dispersions, with very light sedimentation occurring in examples 2A and 2C, the latter due to the high ratio of calcium carbonate: microcrystalline cellulose. Examples 2B and 2D were also dispersed with 0.5% solids and also formed stable dispersions at this level. This example demonstrates that a broad scale of quantities and ratios of components of the composition can be used.

EXAMPLE 3 The colloidal content of the eroded compositions of Example 2 was determined by a centrifugation at 8250 rpm for 15 minutes followed by gravimetric analysis of the dried supernatant product. The amount of colloidal material in the product of Example 1 was determined to be 49.4%, but, since calcium carbonate comprises 50% of the composition, the colloidal content of the cellulose plus carboxymethylcellulose is 98.8%. Similar determinations were made for the products of examples 2A to 2D. These determinations are shown in table 2.

TABLE 2 Colloidal percentage Example Composition Cellulose3 2A 52.9 96.1 2B 74.0 98.7 2C 39.0 100.0 2D 80.0 94.1 a based on total cellulose and carboxymethylcellulose EXAMPLE 4 In a Hobart mixing bowl, 250 grams of ground limestone were placed having a particle size of about 0.8 microns, 576.9 grams of moist hydrolyzed cellulose cake, and 26.9 grams of carboxymethylcellulose of medium viscosity. The ratio of solids comprising this mixture was 45 parts of cellulose, 50 parts of calcium carbonate and 5 parts of carboxymethylcellulose. The mixer was operated for 5 minutes until the composition became uniform. Subsequently the composition was transferred to a twin screw extruder which operated at 150 rpm with the outlet gate set at 25.4 mm for two passages. The product was dispersed in water with 8% solids and homogenized at 17.236.9 kPa. Subsequently, the dispersion was spray dried at an interior temperature of 200 ° C and an outside temperature of 100 ° C. Dispersions prepared in a Waring blender containing 0.5% and 1% of the produced powder were stable although a slight sediment was recorded in each. It was determined by the method of Example 3 that the colloidal content of the composition was 49.4%, indicating that the combined cellulose and carboxymethylcellulose had a colloidal content of 98.8%. This composition was identified as Example 4A. Additional compositions were prepared in the same way, using calcium carbonate having different sizes of average particles. These were identified in table 3 as examples 4B through 4E.

Table 3 Colloidal Content Example CaCO3 particle size Composition Cellulose3 (microns) (%) (%) 4A 0.8 49.40 98.8 4B 3.5 48.80 97.8 4C 5.5 57.8 115.6 4D 8.0 50.00 100.0 4E 12-13 51.25 102.5 to cellulose plus carboxymethylcellulose EXAMPLE 5 In a Hobart mixing bowl, 400 grams of ground limestone (particle size-8.0 microns), 974.4 grams of hydrolysed cellulose wet cake, and 21.5 grams of high viscosity carboxymethylcellulose were placed. The ratio of solids comprising this mixture was 47.5 parts of cellulose, 50 parts of calcium carbonate and 2.5 parts of carboxymethylcellulose. The mixer was operated until the composition became uniform. Subsequently the composition was transferred to a twin screw extruder which operated at 150 rpm with the outlet gate initially fixed at 1.59 mm which was increased to 6.35 mm for the first step and 25.4 mm for the second step. The product was dispersed in water with 8% solids and homogenized at 17.236.9 kPa. Subsequently, the dispersion was spray-dried at an inlet temperature of 200 ° C and an outlet temperature of 100 ° C. The resulting dry powder was dispersed in water using a Waring blender producing stable dispersions with 1% and 1.5% solids. It was determined that the percentage of colloidal material in the composition was 41.9%, indicating a colloidal content of 83.84% cellulose (microcrystalline cellulose plus MCC). In comparison with other compositions containing medium viscosity carboxymethylcellulose, this composition required increasing its shear stress to disperse it. This is example 5A. A second composition of 872 grams of moist hydrolyzed cellulose cake, 400 grams of ground limestone (particle size -8.0 microns), and 64.5 grams of low viscosity carboxymethylcellulose was prepared, in exactly the same manner however the outlet slide of the Double screw extruder was maintained at 25.4 mm through the procedure. This ratio of solids comprising this mixture was 42.5 parts of cellulose, 50 parts of calcium carbonate and 7.5 parts of carboxymethylcellulose. The dried powder that was produced was completely dispersed in water with 0.5%, 1.0% and 1.5% solids using a Lightnin 'mixer for 5 minutes. Only the 1.5% dispersion remained stable with a slightly light sediment. Colloidal matter in this composition was determined at 52.0%, indicating that the colloidal content of cellulose (microcrystalline cellulose plus CMC) was 104%. This is example 5B.

EXAMPLE 6 In a 9.46 liter Hobart mixing bowl, 1153.85 grams of moist hydrolyzed cellulose cake, 500 grams of calcium carbonate, and 53.82 grams of lower methoxypectin were placed. The ratio of solids comprising this mixture was 45 parts of cellulose, 50 parts of calcium carbonate and 5 parts of lower methoxypectin. This was mixed until a homogenous mass was achieved. This mixture was passed through a twin screw extruder three times. A portion (447.95 grams) of the weathered mixture was placed in a 5 liter Waring blender, and 1302.5 grams of deionized water was added. This mixture was dispersed at low speed, providing a dispersion containing 15% solids. This dispersion step was repeated once. The dispersions were combined and homogenized at 17,236.9 kPa before being spray dried. The spray dryer inlet was set at 210 ° C and the outlet at 110 ° C. A total of 384 grams of dry powder was recovered after the drying step.

EXAMPLE 7 By the method of Example 1, 576.9 grams of moist hydrolyzed cellulose cake, 250 grams of tricalcium phosphate (Ksp = 2.07 x 10 ~ 33), 26.9 grams of carboxymethylcellulose of medium viscosity and 45 ml of water were mixed and passed to through a double screw extruder. A dispersion of the product in water was examined using a microscope. This indicated that both the cellulose and the tricalcium phosphate particles were sub-micron in size.

EXAMPLE 8 By the method of Example 4, 1730.8 grams of moist hydrolyzed cellulose cake, 750 grams of dicalcium phosphate (K5p = 1.55 x 10 ~ 7), and 80.64 grams of carboxymethylcellulose of medium viscosity were mixed and worn. The ratio of solids comprising this mixture was 45 parts of cellulose, 50 parts of dicalcium phosphate, and 5 parts of carboxymethylcellulose. Microscopic examination of a 2% dispersion of this material indicated that the microcrystalline cellulose was virtually 100% colloidal. An 8% dispersion of this material was spray-dried under the conditions of example 1. A 1% dispersion of the spray-dried powder in water was stable, but a 0.5% dispersion exhibited some sedimentation. These results are essentially the same as those obtained with the product of example 4. The viscosities of dispersions containing 1%, 2%, 3% and 4% solids were approximately one-half of the corresponding dispersions of the material made in Example 4 EXAMPLE 9 By the method of Example 4, 576.9 grams of moist hydrolyzed cellulose cake, 250 grams of calcium sulfate (K5p = 4.93 x 10"5), and 26.9 grams of carboxymethylcellulose of average viscosity were mixed and weathered. They comprise this mixture was 45 parts of cellulose, 50 parts of calcium sulfate, and 5 parts of carboxymethylcellulose.After the wear was completed, attempts to disperse the wet cake without drying in water were useless since the microcrystalline cellulose was flocculated, possibly due to the constant high solubility for calcium sulfate.

EXAMPLE 10 In a Hobart mixing bowl of 9.46 liters (10 qt) were placed 1153.85 grams of wet cake of hydrolyzed cellulose, 500 grams of titanium dioxide, and 53.76 grams of carboxymethylcellulose of medium viscosity. The ratio of solids comprising this mixture was 45 parts of cellulose, 50 parts of titanium dioxide, and 5 parts of carboxymethylcellulose of medium viscosity. This was mixed until a homogenous mass was achieved. This mixture was passed through a double screw extruder 3 times. A portion (1144.78 grams) of weathered mixture was placed in a colloid mill which was stirred with a Lightnin 'mixer to improve sample circulation, and 7355.22 grams of deionized water was added. This mixture was ground for 10 minutes in a 60 degree rheostat, providing a dispersion containing 8% solids. Upon completion of grinding, the sample was homogenized at 17.236.9 kPa before being spray dried. The spray dryer inlet was set at 210 ° C and the outlet at 110 ° C. A total of 100 grams of dry powder was recovered after the drying step. A dispersion of solids at 0.5% of this powder in water remained completely stable.

EXAMPLE 11 By the method of Example 4, 417.23 grams of wet hydrolyzed cellulose cake, 180.8 grams of talc, and 19. grams of carboxymethylcellulose of medium viscosity were mixed and worn. The ratio of solids comprising this mixture was 45 parts of cellulose, 50 parts of talc, and 5 parts of carboxymethylcellulose. After spray drying by the method of Example 1, a 1% aqueous dispersion of the spray-dried powder in water was found stable, but a 0.5% dispersion was not stable.

EXAMPLE 12 By the method of Example 4, 1153.8 grams of hydrolysed cellulose wet cake, 515.5 grams of lactose (solubility in water = 27% at 100 ° C), and 53.8 were mixed and worn. grams of carboxymethylcellulose of medium viscosity. The ratio of solids comprising this mixture was 45 parts of cellulose, 50 parts of lactose, and 5 parts of carboxymethylcellulose. A 7% solids dispersion was prepared and homogenized at 17,236.9 kPa before being spray-dried as in Example 1. When a 1% solids dispersion was prepared in water, the spray-dried powder was dispersed with great ease .

EXAMPLE 13 Into a 1200 ml stainless steel beaker were placed 547.25 grams of commercial skim milk. To this milk was added with agitation 2.75 grams of powder produced in Example 1. After the mixture was completed, it was heated to 79.4 ° C in a water bath. Subsequently, the mixture was homogenized in two stages. The first stage at 17,236.9 kPa and the second stage at 3,447.4 kPa. After homogenization, the milk was cooled to 4 ° C in a cooling bath. At the end of cooling, milk was observed to determine the degree to which the precipitate appeared, later it was observed a week later to determine the degree that a precipitate formed in storage. The Results of examples 13A through 13G are shown in table 4.

TABLE 4 MCC / CaCO3 Observations Observations Example Initial source of seven days 13A Ex 1 Stable, did not precipitate in precipitated form important 13B Ex 4B Stable, did not precipitate slightly precipitated 13C Ex 4C Stable, did not precipitate precipitated3 slightly 13D Ex 4D Stable , did not precipitate very precipitated slightly 13E Ex 4E Stable, did not precipitate very precipitated slightly 13F Ex 6A was precipitated in Importantly important form precipitated 13G Ex 6B was precipitated in It was precipitated very importantly slightly 3A very light drying was felt on the tongue when this fortified skim milk was tested.

All the above formulations were considered as acceptable with the possible exception of 13F, which was barely accepted, and resulted in a milk fortified with calcium containing 40% more calcium than the initial skimmed milk. A fortified low-fat milk was prepared using a similar procedure by adding 0.25% by weight of the composition of Example 4A and 0.016% by weight of Seakem® CM 611 carrageenan to low-fat milk containing 96.46% by weight of skim milk and 3.28% by weight heavy cream fat (38%). With the exception of heavy cream, all percentages by weight are based on the total weight of the fortified low-fat milk. This low-fat milk provides 120 milligram additional portions of calcium per 240 milliliters.

EXAMPLE 14 To 375.96 grams of water in a large stainless steel beaker were added 2.25 grams of wet cake of hydrolyzed cellulose (45 parts), calcium carbonate (50 parts), and carboxymethylcellulose of medium viscosity (5 parts) prepared in the example 1. The microcrystalline cellulose was dispersed for 10 minutes using a Lightnin 'mixer. At the end of the dispersion, a dry mixture of 0.515 grams of vitamins and minerals (premix) ®, 3.55 grams of soy protein isolate, and 0.075 grams of carrageenan (Viscarin ® GP 209) were added to the dispersion which was subsequently mixed during 30 minutes. Finally, 12.5 grams of corn oil, 43 grams of corn syrup solids (24 DE), 33 grams of granulated sucrose, 16.5 grams of skimmed milk powder, 3 grams each of red Dutch cocoa and natural cocoa were added to the mixture. , 1.5 grams of potassium citrate, 1.4 grams of soy lecithin, 1.25 grams of vanilla flavor, 1.15 grams of potassium chloride, 1 gram of dipotassium phosphate, and 0.35 grams of sodium chloride, which was subsequently stirred for 5 minutes . The mixture was then pasteurized in a short-time pasteurization apparatus at an elevated temperature at 79 ° C for 3 seconds. After pasteurization, the mixture was homogenized in two stages, 20,684 kPa and 3,447.4 kPa. After cooling, the mixture was bottled and remained at rest for at least 16 hours before being examined visually. The viscosity was measured at 5 ° C using a Brookfield LVF viscometer equipped with Spindle # 1 operated at 60 rpm. After rest undisturbed for more than 72 hours, the mixture was stirred and observed and a second viscosity measurement was taken. The formulas for the three products, designated in examples 1A, 14B and 14C are shown in table 5.

TABLE 5 Example 14A 14B 14C Ingredients (%) (%) (%) Water 75,192 74,792 75,092 Corn syrup solids 8,600 8,600 8,600 24DE Sucrose, granulated 6,600 6,600 6,600 Skim milk powder 3,300 3,300 3,300 Corn oil 2,500 2,500 2,500 Soy protein isolate 0.710 0.710 0.710 MCC / CaCO3 / CMCa 0.450 0.850 - Microcrystalline cellulose - - 0.450 Cocoa, Dutch red 0.600 0.600 0.600 cocoa, natural 0.600 0.600 0.600 Potassium citrate 0.300 0.300 0.300 Soy lecithin 0.280 0.280 0.280 Vanilla flavor 0.250 0.250 0.250 Potassium Chloride 0.230 0.230 0.230 Dipotassium phosphate 0.200 0.200 0.200 Premix of 0.103 0.103 0.103 Vitamin / Mineral Sodium Chloride 0.070 0.070 0.070 Carrageenan 0.015 0.015 0.015 Calcium carbonate - - 0.100 aProduct of example 1 bAvicel® CL-611, FMC Corporation, Philadelphia, PA 19103 cViscarin® GP 209, FMC Corporation, Philadelphia, PA 19103 Table 6 shows the properties of examples 14A, 14B, and .

TABLE 6 Viscosity Example 14A Visual Classification (cps) 16 hours Veined and carbonate precipitate of 41.5 fine calcium 72 hours Coarse particles, some precipitate of 47 fine calcium carbonate, without veining or spotting 14B 16 hours Tasting to the slightly sandy palate, veined 113a, and Calcium carbonate precipitate 72 hours No sedimentation, veining, or spotting 97.5a 14C 16 hours A lot of sedimentation of cocoa, calcium carbonate 38.5, and / or vitamins and minerals 72 hours Sedimentation of calcium carbonate and 48 some coarse cocoa particles a Measured with spindle # 2 operated at 60 rpm. Example 14A produced a very acceptable product with a desired viscosity and minimum precipitate that can easily be dispersed upon agitation. Example 14B was found too viscous due to the higher level of MCC employed. Example 14C was less satisfactory, exhibiting much sedimentation both a. the 16 as at 72 hours. This example demonstrates that the composition can be effectively used in nutritious drinks. It also illustrates the improvement over dispersions made with cellulose from Avicel® CL-611.

EXAMPLE 15 In a stirred container with a Lightnin 'mixer, 2692.4 grams of skim milk and 400 grams of heavy cream were placed. This mixture was mixed for approximately 5 minutes before adding a dry mixture of 266.8 grams of skimmed milk powder, 400 grams of sugar, 210 grams of corn syrup solids (42DE), 16 grams of wet cake of hydrolyzed cellulose weathered / calcium carbonate / carboxymethylcellulose powder (example 1) 0.8 grams of carrageenan (Lactarin® IC 1222 sold by FMC Corporation), 4 grams of carboxymethylcellulose (Aqualon® 7HF, sold by Hercules Incorporated), and 10 grams of emulsifier (Tandem 100K, a mixture of 80:20 of monoglycerides, diglycerides: Polysorbate 80, sold by Witco Corporation) were added to the vortex of the mixer and mixed for 30 minutes to fully hydrate the gums. At the end of the mixing, the mixture was pasteurized by a short time high temperature method using an ultra high temperature Cherry-Burrel unit operated for 2 minutes at 76.7 ° C. After pasteurization, the mixture was homogenized using an APV Gaulin homogenizer, the first stage was operated at 13,789.5 kPa and the second stage at 3,447.4 kPa. At the end of homogenization, the mixture was cooled and aged overnight in a refrigerator at 1.7-4.4 ° C. There was no separation of the mixture. The following day, 37.9 grams of vanilla flavor was added with gentle stirring with a wooden spoon to avoid incorporation of air into the mixture before cooling in a Taylor continuous freezer. Also, before cooling, the viscosity of 400 ml of mixture was determined at 310 cps using a Brookfield LVF viscometer. A second viscosity measurement, 43 seconds, was made using a # 2 Zahn cup. The increase in volume of the frozen dessert was 65%, and the standard melt yield resulted in a 68 ml melt. A taste test revealed that the ice cream provided equivalent performance to Avicel® RC-581, currently used commercially as a stabilizer in low-fat ice cream, but with added calcium values.

EXAMPLE 16 The amounts of colloidal material in the compositions of this invention were shown to correlate with the total amount of cellulose and carboxymethylcellulose present by the gravimetric method of Example 3. The size of the cellulose particles present in the composition was determined by laser light scattering methods. using a Horiba LA-910 particle size distribution analyzer. The size distribution of pure calcium carbonate was analyzed, providing a normal size distribution. By analyzing the wet cake of hydrolyzed cellulose / calcium carbonate / carboxymethylcellulose an almost identical distribution was obtained with those of calcium carbonate alone, indicating that the relatively large particles of calcium carbonate dominate the analysis and almost completely hide the smaller particles. To improve this effect, the dispersion of the powder prepared in Example 1 was centrifuged at 8000 rpm for 15 minutes. The supernatant was removed and analyzed by light scattering. The Results of this analysis showed that 100% of the particles had sizes smaller than 0.7 μm and that approximately 90% were below 0.3 μm. The scale was 0.1 μm to 0.7 μm, with the average size being slightly less than 0.2 μm. Two commercial products were analyzed by means of gravimetric and light scattering method combined with centrifugation in exactly the same way. A comparison of the results of these three analyzes is shown in table 7.

TABLE 7 Sample Example RC-581a CL-6111 Colloidal gravimetric% 98.8 61.2d 67.4d Particle size distribution Total sample NAe 0.5-275 μm 0.4-50 μm Average particle size NA 17.03 μm 8.29 μm Sample centrifuged 0.1-0.7 μm 0.2-0.9 μm 0.1-0.7 μm Average particle size < 0.2 μm 0.31 μm -0.25 μm ° Percent of colloidal material as determined by the method of Example 3 D on the total sample of cellulose plus carboxymethyl cellulose e Not applicable due to the presence of 50% calcium carbonate Cellulose Avicel® CL-611 is one of the materials of microcrystalline cellulose plus colloidal commercially available today, however only about 67-68% of this material is in the size scale where almost 100% of the material of the invention is found. In addition, the average particle size of Avicel® cellulose CL-611 is significantly larger than that of the invention. Avicel® cellulose RC-581 has a larger average particle size and has less colloidal content than Avicel® cellulose CL-611.

EXAMPLE 17 A small beaker containing 30 grams of propylene glycol was heated to 50 ° C and stirred with a Lightnin 'mixer to dissolve one gram of methylparaben and 0.1 gram of propylparaben. When the mixture was completed, 400 grams of deionized water was added to this solution in a 2-liter mixing bowl. After finishing the mixture, 200 grams of a 70% sorbitol solution (USP) and 1.6 grams of sodium saccharin (USP) were added to the aqueous solution and mixed until complete dissolution was achieved. Next, 100 grams of co-processed microcrystalline cellulose / calcium carbonate / carboxymethylcellulose powder prepared as described in Example 4 was added and dispersed using a Scott Turbon mixer operated at 2000 rpm for a period of 10 minutes. Sufficient deionized water was added to bring the total volume of this dispersion up to one liter, and the suspension was mixed until it became uniform. This refined suspension was poured and had a viscosity of 120 cps when measured by a Carrimed rheometer operated at 6 rpm. First, the suspension appeared to be stable and remained stable after storage periods of 3 months at 4 ° C, 25 ° C, 30 ° C, and 40 ° C. A 10 ml portion of this antacid suspension was able to neutralize 11.5 milliequivalents of acid.

EXAMPLE 18 A small beaker containing 15 grams of propylene glycol was heated to 50 ° C and stirred with a Lightnin 'mixer to dissolve 0.5 grams of methyl paraben and 0.05 grams of propyl paraben. When the mixture was completed, 200 grams of deionized water were added to this solution in a 1 liter mixing bowl. After finishing the mixture, 100 grams of a 70% sorbitol solution (USP), and 0.8 grams of sodium saccharin (USP) were added to the aqueous solution and mixed until complete dissolution was achieved. Next, 75 grams of co-processed microcrystalline cellulose / calcium carbonate / carboxymethylcellulose powder was added as described in Example 4 and dispersed using a Lightnin mixer for a period of 10 minutes. Sufficient deionized water was added to reach a total volume of this dispersion up to 0.5 liters, and the suspension was mixed until it became uniform and had the appearance of whipped cream. To 5 ml of this whipped suspension were added 160 milligrams of acetaminophen. The ingredients were mixed well, producing a suspension of whipped cream that can be dosed with acetaminophen spoon.

Claims (21)

NOVELTY OF THE INVENTION CLAIMS

1. - An ultrafine weathered microcrystalline cellulose composition comprising microcrystalline cellulose particles of 80% to 100% which have a particle size no greater than 1 μ, a wear aid which is an ionic material having an equal or lesser aqueous K5p at 1x10"7 or a powder or granular material having a solubility in water equal to or less than 40% at 100 ° C, and optionally a protective colloid

2. The composition according to claim 1, further characterized in that the The weight ratio of the microcrystalline cellulose to the wear aid is in the range of 85:15 to 30:70 and the weight ratio of the microcrystalline cellulose to the protective colloid when present is in the range of 95: 5 to 70:30

3. The composition according to claim 1, further characterized in that the wear aid is selected from a group consisting of calcium carbonate, titanium dioxide, phosphate of tricalcium, dicalcium phosphate, silica, talc, and lactose.

4. The composition according to claim 1, further characterized in that a protective colloid is employed.

5. - The composition according to claim 1, further characterized in that at least 90% of the microcrystalline cellulose has a particle size not greater than 0.75 μ.

6. The composition according to claim 1, further characterized in that the average particle size of the icrocrystalline cellulose is on the scale of about 0.1 μ to 0.7 μ.

7. The composition according to claim 1, further characterized in that the dry residue of a suspension of microcrystalline cellulose, a wear aid is selected from a group consisting of calcium carbonate, titanium dioxide, tricalcium phosphate, phosphate of dicalcium, talc, and lactose and a protective colloid is selected from a group consisting of carboxymethyl cellulose and pectin.

8. The composition according to claim 1, further characterized in that the particle size of said microcrystalline cellulose particles is produced by high-solids wet milling of the microcrystalline cellulose wet cake in the presence of said auxiliary of wear.

9. The composition according to claim 7, further characterized in that the particle size of said microcrystalline cellulose particles is produced by wet grinding a high solids content of the microcrystalline cellulose wet cake in the presence of said auxiliary of wear.

10. - A process for preparing an ultrafine microcrystalline cellulose composition comprising: (a) mixing unspent microcrystalline cellulose, a wear agent which is an ionic material having an aqueous K5p equal to or less than 1 × 10 ~ 7 or a material in powder or granulate having a solubility in water equal to or less than 40% at 100 ° C, and optionally a protective colloid, in which the solid content represented by the microcrystalline cellulose and the wear agent is in the range of 30 % to 80% by weight of the mixture, the weight ratio of the microcrystalline cellulose to the wear agent is in the range of 85:15 to 30:70, and the weight ratio of the microcrystalline cellulose to the protective colloid, when it is used, it is in the range of 95: 5 to 70:30, (b) subjecting the mixture to wet milling with high high shear stress for a time and under shear forces sufficient to reduce the microcrystalline cellulose to a particle size in which 80% to 100% of the microcrystalline cellulose present, has a particle size no greater than 1 μ; and (c) recovering the resulting ultrafine microcrystalline cellulose composition.

11. The process according to claim 10 further characterized in that the wear agent is selected from a group consisting of calcium carbonate, titanium dioxide, tricalcium phosphate, dicalcium phosphate, silica, talc and lactose.

12. The method according to claim 11 further characterized in that a protective colloid is used.

13. - A calcium fortified food product comprising a dispersion of a nutrient suspended in a stabilized amount of composition according to claim 1.

14. The product according to claim 13, further characterized in that it includes a therapeutic or complementary amount of vitamins, minerals or both.

15. A milk product fortified with calcium further characterized in that the dairy product is stabilized with the composition according to claim 1.

16. The composition according to claim 15, further characterized in that the dairy product is low-fat milk .

17. A food product comprising a frozen dessert that is stabilized with the composition according to claim 1.

18. A composition comprising the composition according to claim 1 together with water and a biologically effective amount of an agent pharmaceutically substantially insoluble in water.

19. An ultrafine weathered microcrystalline cellulose composition according to claim 1, further characterized in that it comprises microcrystalline cellulose particles that when dispersed have a particle size distribution such that at least 95% of the microcrystalline cellulose has a particle size no greater than 0.7 μ and be colloidally stable.

20. - An aqueous slurry suspension comprising the composition according to claim 1 together with one or more additional ingredients selected from a group consisting of an alkyl glycol, alkyl paraben, sorbitol, saccharin and a mixture thereof.

21. A whipped suspension that is dosed with a spoon having an appearance, texture and consistency of whipped cream, further characterized in that it comprises the composition according to claim 1 together with one or more additional ingredients selected from a group consisting of a alkyl glycol, alkyl paraben, sorbitol, saccharin and mixtures thereof.