Micronized starch and methods for its production

Description

INTRODUCTION

[0001] The present application is related to a micronized starch with an average particle size of less than 5 µm and a degree of polymerization greater than 100, wherein the micronized starch exhibits at least 20% of the crystallinity of the base granular starch.

[0002] Starch is a complex carbohydrate composed of two types of polysaccharide molecules; (1) amylose, a mostly linear and flexible polymer of D-anhydroglucose units that are linked by alpha-1,4-D-glucosidic bonds; and (2) amylopectin, a branched polymer of linear chains that are linked by alpha-1,6-D-glucosidic bonds. Starch has an equilibrium moisture content of 10% to 20% at normal atmospheric conditions depending on source. Cereal starches are usually about 10% to 14% moisture, while potato starch is usually about 15% to 20% moisture.

[0003] Native starches have many disadvantages for industrial applications such as insolubility in cold water, loss of viscosity, and thickening power after cooking. Starch can be physically modified to improve water solubility and to change particle size. The physical modification methods involve the treatment of native starch granules under different temperature / moisture combinations, pressure, shear, and irradiation. Physical modification also includes mechanical attrition to alter the physical size of starch granules.

[0004] Starch granules occur in all shapes and sizes (spheres, ellipsoids, polygons, platelets, irregular tubules). The long dimensions of these starch granules range from 0.1 µm to at least 200 µm, depending on the botanical source, Gallant et al. Eur. J. Clinical Nutr. 1992, 46, S3. Starch produced by wet-milling of normal corn kernels has a granular size of 5-30 µm with a reported average size of 9.2 µm, "Corn Starch, 3rd edition" Washington, DC: Corn Industries Research Foundation; 1964. The larger, waxy corn starch granules have X-ray diffraction patterns of the A-type, Franco et al. 1998 Starch / Stärke, 50, 193-198. Starch granules are made up of alternating amorphous and crystalline shells which are between 100 nm and 400 run thick. X-ray diffraction shows a periodicity of 9 to 10 nm within the granules. The periodicity is due to the crystalline and amorphous thin plates in the granules and is independent of the botanical source.

[0005] Native starch granules have a crystallinity varying from 15% to 45%, Zobel Starch / Starke, 1988, 40, 44. From the level of starch crystallinity, it is clear that most starch polymers in the granule are amorphous. Oostergetel et al. Carbohydrate Polymers, 1993, 21, 7. Most native starch granules exhibit a Maltese cross when observed under polarized light. Radial organization of amylopectin molecules within such structures causes the optical polarization. However, this birefringence remains unchanged on both polar and equatorial sections of elongated starch granules, Gallant et al. Eur. J. Clinical Nutr., 1992, 46, S3 indicating that crystallites are extremely small and exhibit multiple orientations.

[0006] Native starch granules give X-ray diffraction patterns, which lack sharp peaks. These X-ray patterns are used to identify the several allomorphs present in crystalline starch, Buleon et al. Int. J. Biol. Macromol, 1998, 23, 85. The larger A-type starch granules have a disk shape, whereas the smaller B-type starch granules have a spherical shape. Cereal starches have the A-type polymorph; tuber starches (e.g. potato) and cereal starches rich in amylose contain the B-type polymorph, and legume starches have the C-type polymorph.

[0007] The A-type starch crystal is in the monoclinic space group B 2 (a = 2.124 nm, b= 1.172 nm, c = 1.069 nm, γ = 123.5°) with 12 glucosyl units and 4 water molecules in the unit cell. This means the asymmetric unit contains a maltotriosyl unit, and that the packing contains one double helix at the corner and another at the center of the unit cell. The double helix is left-handed, is parallel-stranded, has a repeat distance of 2.138 nm, and is related to the other strand by a twofold axis of rotation. The double helix is very compact, and there is no space for water in the center of the helix. There are hydrogen bonds between these helices, either direct or through the four water molecules in the unit cell.

[0008] The B-type starch crystal is in the hexagonal space group P6 1 (a = b = 1.85 run, c = 1.04 nm). The chains in B-type starch are also organized in double helices, but the structure differs from A-type starch in crystal packing and water content, the latter ranging from 10% to 50%. Double helices are connected through a network of hydrogen bonds that form a channel inside the hexagonal arrangement of six double helices. This channel is filled with water molecules, half of which are bound to amylose by hydrogen bonds and the other half to other water molecules. Thus, with a hydration of 27%, 36 water molecules are located in the unit cell between the six double helices, creating a column of water surrounded by the hexagonal network.

[0009] Jane et al. Cereal Chem. 1990, 69, 280 reported that normal corn starch after 12 hours in a ball mill (presumably without any added solvent), "retained integrity and showed no broken pieces". If the corn starch was first subjected to acid hydrolysis under various conditions, then milled for 8 hours in a ball-mill in the presence of 100% ethyl alcohol gave between 66% and 80% yield of a small-particle starch. This small particle starch had a volume density size between 5.2 ± 2.4 µm and 8.6 ± 4.7 µm compared to 17.2 ± 7.9 µm in the native starch. The small particle starch showed a strong birefringence but the Maltese cross was lost as a result of lost symmetry and spherical shape found in the native starch granules. The small particle starch produced a sharp A-type X-ray diffraction pattern with an intensity greater than seen in the native starch. This suggests that acid treatment preferentially removed the amorphous portions of the starch granule. The small particle starches of Jane et al. Cereal Chem. 1990, 69, 280 are depolymererized with an average degree of polymerization (DP) of 48.9 to 56.3.

[0010] Wu et al. Carbohydrate Polymers, 2008, 72, 398-402 prepared corn flour samples with different particle size by ball milling. A commercial corn flour with a 273.6 µm size could be micronized to 17.5 µm, 15.4 µm, 14.6 µm, 13.3 µm, and 9.8 µm in median diameter by wet-milling for 20 minutes, 1 hour, 2 hours, 3 hours, and 5 hours, respectively. Microscopic observation and X-ray diffractometry revealed the starch crystal structure of corn flour was destroyed by wet-milling for more than 3 hours.

[0011] Herceg et al. Carbohydrate Polymers 2010, 80, 1072 reports that tribomechanical micronization and activation, a process of treating solids with two closely spaced parallel discs rotating at a speed of 20,000 rpm, reduced corn starch from an average particle size of about 14 µm to about 12.5 µm. These micronized starch particles were more permeable to water, had increased water solubility, showed increased swelling power, had a lowered beginning of gelatinization temperature, and a decreased in enthalpy of gelatinization. The authors concluded, "[t]he crystalline molecular structure of corn starch is broken".SUMMARY

[0012] In one aspect the application provides a micronized starch with an average particle size of less than 5 µm and a degree of polymerization greater than 100, wherein the micronized starch exhibits at least 20% of the crystallinity of the base granular starch.BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Fig. 1A depicts a scanning electron microscopy image of AMIOCA ®< starch granules before micronization. Fig. 1B depicts a scanning electron microscopy image of AMIOCA ®< starch granules after micronization where the granules were dehydrated prior to micronization (1B). Fig. 1C depicts a scanning electron microscopy image of AMIOCA ®< starch granules after micronization. Fig. 2A depicts a scanning electron microscopy image of HYLON ®< VII starch granules before micronization. Fig. 2B depicts a scanning electron microscopy image of HYLON ®< VII starch granules after micronization where the granules were dehydrated prior to micronization (1B). Fig. 2C depicts a scanning electron microscopy image of HYLON ®< VII starch granules after micronization. Fig. 3A depicts a scanning electron microscopy image of MELOJEL ®< starch granules before micronization. Fig. 3B depicts a scanning electron microscopy image of MELOJEL ®< starch granules after micronization where the granules were optionally dehydrated prior to micronization. Fig. 3C depicts a scanning electron microscopy image of MELOJEL ®< starch granules after micronization. Fig. 4 depicts X-ray diffraction analysis of crystallinity of base granular and micronized AMIOCA ®< starch. Fig. 5 depicts X-ray diffraction analysis of crystallinity of base granular and micronized MELOJEL ®< starch. Fig. 6 depicts X-ray diffraction analysis of crystallinity of base granular and micronized HYLON ®< VII starch. Fig. 7A depicts polarized light microscopy (400x) photographs of base granular AMIOCA ®< starch. Fig. 7B depicts polarized light microscopy (400x) photographs of micronized AMIOCA ®< starch. Fig. 8A depicts polarized light microscopy (400x) photographs of base granular HYLON ®< VII starch. Fig. 8B depicts polarized light microscopy (400x) photographs of micronized HYLON ®< VII starch. Fig. 9A depicts polarized light microscopy (400x) photographs of base granular MELOJEL ®< starch. Fig. 9B depicts polarized light microscopy (400x) photographs of micronized MELOJEL ®< dent corn starch. Fig. 10 depicts melting enthalpy of AMIOCA ®< base granular starch as compared to melting enthalpy of micronized AMIOCA ®< starch. Fig. 11 depicts melting enthalpy of HYLON ®< VII base starch as compared to melting enthalpy of micronized HYLON ®< VII starch. Fig. 12 depicts melting enthalpy of MELOJEL ®< base granular starch as compared to melting enthalpy of micronized MELOJEL ®< starch. Fig. 13 depicts Brabender viscosity curve results obtained from base granular and micronized AMIOCA ®< starch and MELOJEL ®< starch as well as rice and saponin. Fig. 14A depicts a comparison of crushing strength (kPa) of tablets manufactured with various industry standard components (microcrystalline cellulose, etc.) and with base and micronized AMIOCA ®< starch. Fig. 14B depicts a comparison of crushing strength (kPa) of tablets manufactured with various industry standard components (microcrystalline cellulose, etc.) and with base and micronized HYLON ®< VII starch. Fig. 14C depicts a comparison of crushing strength (kPa) of tablets manufactured with various industry standard components (microcrystalline cellulose, etc.) and with base and micronized granular starches (AMIOCA ®< starch; HYLON ®< VII starch; MELOJEL ®< starch). Fig. 15A depicts a particle size analysis of AMIOCA ®< starch before micronization. Fig. 15B depicts a particle size analysis of AMIOCA ®< starch after micronization. DETAILED DESCRIPTION

[0014] In one aspect, the application provides a micronized starch as claimed in claim 1 with an average particle size of less than 5 µm and a degree of polymerization greater than 100, wherein the micronized starch exhibits at least 20% of the crystallinity of the base granular starch, the micronized starch having an average particle size of at least 20% less than the average particle size of the base granular starch.

[0015] In one embodiment, the micronized starch exhibits at least 60% of the crystallinity of the base granular starch.

[0016] In one embodiment, the micronized starch exhibits at most 90% of the crystallinity of the base granular starch.

[0017] In one embodiment, the base granular starch is a cereal starch.

[0018] In one embodiment, the base granular starch is a corn starch.

[0019] In one embodiment, the melting enthalpy of the micronized starch is at least 50% of the melting enthalpy of the base granular starch.

[0020] In one embodiment, the gelatinization temperature of the micronized starch is no more than 16° C different than the gelatinization temperature of the base granular starch.

[0021] In one embodiment, the peak viscosity of the micronized starch is not greater than 90% of the peak viscosity of the base granular starch.

[0022] In one embodiment, the degree of polymerization of the micronized starch is greater than 1,000.

[0023] In one embodiment, the degree of polymerization of the micronized starch is greater than 10,000.

[0024] In one aspect the application provides a tablet as claimed in claim 11 comprising the micronized starch and at least one other pharmaceutically acceptable ingredient.

[0025] In one embodiment, the tablet is characterized by a crushing strength of at least 20 kPa at a compression pressure of 20.68 MPa [3000 PSI] in a tablet consisting only of the starch.

[0026] In one aspect the application provides a method of reducing starch particle size as claimed in claim 13 comprising the steps of: a) dehydrating a base granular starch to a moisture content of less than 5% on a w / w basis, and b) micronization of the dehydrated base granular starch in a environment containing less than 5% oxygen in a v / v basis to result in a micronized starch; wherein the micronized starch has a moisture content of no greater than 5% on a w / w basis of the base granular starch; wherein the micronized starch comprises an average particle size of less than 5 µm; wherein the degree of polymerization of the micronized starch is greater than 100; and wherein the micronized starch exhibits at least 20% of the crystallinity of the base granular starch, and wherein the micronized starch has an average particle size of at least 20% less than the average particle size of the base granular starch.

[0027] In one embodiment, the environment containing less than 5% oxygen in a v / v basis is comprised of inert gas.

[0028] The starch of the instant application is micronized so as to result in the inventive product. Micronization can be accomplished in any manner known to one of skill in the art for particle size reduction (for example and without limitation, ball micronizing; media micronizing; fluidized bed jet micronizing; spiral jet micronizing; air classifying micronizing; universal pin micronizing; hammer and screen micronizing; attrition micronizing; cone micronizing; and / or granulating). One example of a micronization process is fluidized bed jet milling. One example of such a fluidized bed jet mill is the Hosokawa ™< 100 AFG Fluidized Bed Jet Mill.

[0029] Base granular starch is dehydrated and then micronized under sufficient conditions so that any remaining moisture in the base granular starch is insufficient to gelatinize the starch.

[0030] In one embodiment, an inert gas "purge" is utilized during micronization to create and maintain an environment containing less than 5% oxygen in a v / v basis. In another embodiment, any type of gas can be used during micronization. Such inert gases include, but are not limited to, nitrogen, carbon dioxide, argon, or helium. In another embodiment, the dry gas has a water dew-point of about -45 °C. In another embodiment, the dry gas has a water dew-point of about - 65 °C. In another embodiment, the dry gas has a water content less than 6 ppm. In another embodiment, the dry gas has a water content less than 1 ppm.

[0031] In one embodiment, a base granular starch is micronized in a fluidized bed jet mill in an environment containing less than 5% oxygen in a v / v basis.

[0032] Fig. 1A, Fig. 1B, and Fig. 1C (AMIOCA ®< starch), Fig. 2A, Fig. 2B, and Fig. 2C (HYLON ®< VII starch), and Fig. 3A, Fig 3B, and Fig. 3C (MELOJEL ®< starch) and accompanying Examples 1 and 13 depict and describe base granular starches and micronized starches prepared in accordance with the micronization procedures discussed above.

[0033] The native starch is sourced from corn, pea, potato, sweet potato, banana, barley, wheat, sago, oat, amaranth, tapioca, arrowroot, canna, sorghum, and waxy or high amylose varieties thereof. As used herein, the term "waxy" is intended to include a starch containing at least about 90%, in one embodiment at least 95%, in one embodiment at least 98, in one embodiment at least 99%, by weight amylopectin and the term "high amylose" is intended to include a starch containing at least about 40%, in one embodiment at least 50%, in one embodiment at least 70%, in one embodiment at least 80%, by weight amylose. In one aspect of this application, amylose-containing starch extracted from cereal grains, such as corn, are used. In another aspect of this application, blends of starches are used, such as a blend of corn starch and high amylose corn starch.

[0034] A base starch can be a native starch or a native starch modified by any treatment. One example of such a base starch is AMIOCA ®< starch. Another example of such a base starch is MELOJEL ®< starch. Another example of such a base starch is HYLON ®< VII starch.

[0035] In one embodiment, the average particle size of the base granular starch is between about 5 µm and about 200 µm. In another embodiment, the average particle size of the base granular starch is at least about 5 µm. In another embodiment, the average particle size of the base granular starch is at least about 10 µm, In another embodiment, the average particle size of the base granular starch is between about 5 µm and about 20 µm. In another embodiment, the average particle size of the base granular starch is between about 5 µm and about 100 µm. In another embodiment, the mean average particle size of the micronized starch granules is between about 2 µm and about 4 µm. In another embodiment, the average particle size of the micronized starch is less than about 3 µm, In another embodiment, the average particle size of the micronized starch is less than about 2 µm. In another embodiment, the average particle size of the micronized starch is less than about 1 µm.

[0036] In one embodiment, the degree of polymerization of the micronized starch is greater than 100. In another embodiment, the degree of polymerization of the micronized starch is greater than 500. In another embodiment, the degree of polymerization of the micronized starch is greater than 1,000. In another embodiment, the degree of polymerization of the micronized starch is greater than 5,000. In another embodiment, the degree of polymerization of the micronized starch is greater than 10,000. In another embodiment, the degree of polymerization of the micronized starch is greater than 50,000.

[0037] In one embodiment, the average particle size of the micronized starch is between about 20% and about 90% of the average particle size of the base granular starch. In another embodiment, the average particle size of the micronized starch is between about 20% and about 80% of the average particle size of the base granular starch. In another embodiment, the average particle size of the micronized starch is between about 30% and about 70% less than the average particle size of the base granular starch. In another embodiment, the average particle size of the micronized starch is between about 40% and about 60% less than the average particle size of the base granular starch. In another embodiment, the average particle size of the micronized starch is no greater than about 90% of the average particle size of the base granular starch. In another embodiment, the average particle size of the micronized starch is no greater than about 80% of the average particle size of the base granular starch. In another embodiment, the average particle size of the micronized starch is no greater than about 70% of the average particle size of the base granular starch. In another embodiment, the average particle size of the micronized starch is no greater than about 60% of the average particle size of the base granular starch. In another embodiment, the average particle size of the micronized starch is no greater than about 50% of the average particle size of the base granular starch. In another embodiment, the average particle size of the micronized starch is no greater than about 40% of the average particle size of the base granular starch. In another embodiment, the average particle size of the micronized starch is no greater than about 30% of the average particle size of the base granular starch. In another embodiment, the average particle size of the micronized starch is no greater than about 20% of the average particle size of the base granular starch.

[0038] In one embodiment, the micronized starch exhibits at least 90% of the crystallinity of the base granular starch. In another embodiment, the micronized starch exhibits at least 80% of the crystallinity of the base granular starch. In another embodiment, the micronized starch exhibits at least 70% of the crystallinity of the base granular starch. In one embodiment, the micronized starch exhibits at least 60% of the crystallinity of the base granular starch. In one embodiment, the micronized starch exhibits at least 50% of the crystallinity of the base granular starch. In one embodiment, between 50% and 90% of the crystallinity of the base granular starch is retained in the micronized starch. In one embodiment, between 70% and 90% of the crystallinity of the base granular starch is retained in the micronized starch. In one embodiment, between 50% and 80% of the crystallinity of the base granular starch is retained in the micronized starch.

[0039] In one embodiment, retention of the crystallinity of the base granular starch in the micronized starch is assayed via X-ray diffraction. In another embodiment, the gelatinization temperature of the micronized starch is not less than 15°C below the gelatinization temperature of the base granular starch.

[0040] In one embodiment, the melting enthalpy (Δ H) of the micronized starch is no less than about 50% of the melting enthalpy (Δ H) of the base granular starch. In another embodiment, the melting enthalpy (Δ H) of the micronized starch is no less than about 70% of the melting enthalpy (Δ H) of the base granular starch. In another embodiment, the melting enthalpy (Δ H) of the micronized starch is no less than about 80% of the melting enthalpy (Δ H) of the base granular starch. In one embodiment, the melting enthalpy (Δ H) of the micronized starch is no less than about 90% of the melting enthalpy (Δ H) of the base granular starch.

[0041] The starch composition may be used as an excipient in tablets. The particle size and moisture content of the micronized starch composition will affect the flowability, density, compressibility, binding, and disintegration properties. The starch composition may be incorporated into this solid dosage form using methods known in the art.DEFINITIONS

[0042] The following definitions are used in connection with the present application unless the context indicates otherwise. All parts and percentages are given by weight and all temperatures in degrees Centigrade (°C) unless otherwise indicated. All percents used are on a weight / weight basis. Unless otherwise specified, all percentages expressed herein are weight / weight. Drierite ®< is a desiccants made from anhydrous calcium sulfate (gypsum). Some varieties contain 3% cobalt (II) chloride, a moisture-sensitive color indicator that shows when that material's activity has been depleted. Drierite ®< is a registered trademark of the W.A. Hammond Drierite Co., Ltd., Xenia, Ohio.

[0043] The term "average particle size" means the mean particle size of a composition of a plurality of particles, as assessed by Polarization Intensity Differential Plus Electric Light Scattering, in accordance with Example 8 herein.

[0044] The term "base starch" means a starch obtained from the same plant source as a corresponding micronized starch that has been processed in the same manner but has not been reduced in average particle size.

[0045] The term "crushing strength" means the force necessary to fragment a dosage form, in accordance with Example 10 herein.

[0046] The term "comminuting" means a method of reducing the average particle size of a material.

[0047] The term "compression pressure" means pressure utilized to compress a sample into tablet form, measured in Newtons.

[0048] The term "crystallinity" means the degree of structural order in a solid. Many materials can be prepared in such a way as to produce a mixture of crystalline and amorphous regions. In such cases, crystallinity is usually specified as a percentage of the volume of the material that is crystalline. Crystallinity can be measured using X-ray diffraction. The percent of crystallinity as assessed by X-ray diffraction and in accordance with Example 3 herein.

[0049] The term "degree of polymerization" or "DP" means the number of D-anhydroglucose units in a starch molecule.

[0050] The term "dehydrating starch to a moisture content" means reducing the moisture content in a starch.

[0051] The term "gelatinized" means that a starch is no longer a granular starch as defined herein.

[0052] The term "gelatinization temperature" means the onset temperature of gelatinization measured in accordance with Example 5 herein.

[0053] The term "granular starch" means raw uncooked starch, i.e., starch in its natural form found in cereal, tubers, or grains. Starch is formed in plants as tiny granules insoluble in water. These granules are preserved in starches at temperatures below the initial gelatinization temperature. When put in cold water, the grains may absorb a small amount of the liquid. Up to 50 °C to 70 °C the swelling is reversible, the degree of reversibility being dependent upon the particular starch. With higher temperatures an irreversible swelling called gelatinization begins.

[0054] The term "melting enthalpy" (Δ H) means the amount of heat required to convert a unit mass of a solid at its melting point into a liquid without an increase in temperature, as assessed utilizing differential scanning calorimetry in accordance with Example 6 herein.

[0055] The term "micronized" means comminuted so as to reduce the average size of a solid material's particles. Usually, the term micronization is used when the particles that are produced are only a few micrometers (µm) in diameter. Micronization can be achieved by processes including, but not limited to, jet milling, pearl-ball milling, high-pressure homogenization, the RESS process (Rapid Expansion of Supercritical Solutions), the SAS method (Supercritical Anti-Solvent), or the PGSS method (Particles from Gas Saturated Solutions).

[0056] The term "moisture content" means the moisture content as measured in accordance with Example 2 herein.

[0057] The term "substantially oxygen-free environment" means an ambient environment having less than about 5% oxygen by volume.

[0058] Certain specific aspects and embodiments of the present application are explained in more detail with reference to the following examples, which are provided only for purposes of illustration and should not be construed as limiting the scope of the application in any manner.EXAMPLES

[0059] Example 1A: Manufacture of a dry-ground, micronized starch. A base granular starch was dehydrated, prior to micronization of the base granular starch, to a moisture less than about 5% on a w / w basis. The base granular starch was manually charged into the hopper, which conveys material to the grind chamber by a screw feeder. The base granular starch was milled under substantially oxygen free conditions created by the use of an inert gas "purge" of the mill during the micronization process to drive off excess moisture. The base granular starch was milled using a Hosokawa ®< 100 AFG Fluidized Bed Jet Mill (20 lbs. capacity) so as to result in a micronized base granular starch.

[0060] 1B Dehydration and micronized of the base granular starch so that any remaining moisture in the base granular starch is insufficient to gelatinize the starch. The base granular starch was dehydrated to a moisture of less than about 5% on a w / w basis prior to micronization. The dehydrated base granular starch was then milled using a Hosokawa ™< 100 AFG Fluidized Bed Jet Mill (20 lbs. capacity) so as to result in a micronized base granular starch using nitrogen gas to create substantially oxygen free conditions in the mill during the micronization process to drive off excess moisture.

[0061] 1C Dehydration of the base granular starch during the micronization process so that any remaining moisture in the base granular starch is insufficient to gelatinize the starch. The base granular starch was milled using a Hosokawa ™< 100 AFG Fluidized Bed Jet Mill (20 lbs. capacity) so as to result in a micronized base granular starch. The base granular starch is not dehydrated prior to the micronization step.

[0062] 1D Partial dehydration of the base granular starch and then further dehydration during the micronization process so that any remaining moisture in the base granular starch is insufficient to gelatinize the starch. The base granular starch was partially dehydrated prior to micronization the base granular starch to a moisture of less than about 5% on a w / w basis. The dehydrated base granular starch was then milled using a 100 AFG Fluidized Bed Jet Mill (20 lbs. capacity) so as to result in a micronized base granular starch. Nitrogen was utilized to create a substantially oxygen free conditions in the mill during the micronization process to drive off excess moisture.

[0063] 1E Dehydration of the base granular starch during the micronization process with the use of an inert gas "purge" to drive off moisture contained within the base granular starch so that any remaining moisture in the base granular starch is insufficient to gelatinize the starch as a result of the heating of the starch (through friction and / or other means) during the micronization process. Nitrogen is utilized to create a substantially oxygen free condition in a Hosokawa ™< 100 AFG Fluidized Bed Jet Mill (20 lbs. capacity) during the micronization process to drive off excess moisture.

[0064] 1F Oven drying of the base granular starch prior to micronization, without the use of a subsequent inert gas "purge" to drive off moisture contained within the base granular starch. The base granular starch was dehydrated prior to micronization the base granular starch to a moisture less than about 5% on a w / w basis. The dehydrated base granular starch with low moisture was then milled using a Hosokawa ™< 100 AFG Fluidized Bed Jet Mill (20 lbs. capacity) so as to result in a micronized base granular starch.

[0065] Example 2: Determining and measuring moisture of micronized starch. Moisture in a starch or dextrin sample is determined by heating a known quantity of sample for 4-6 hours at 130 ± 2° C in a gravity convection oven. Oven moisture determinations may be done on most starch and dextrin products. This method measures the amount of volatiles lost after heating. For test purposes, these volatiles are considered water. This method is also referred to as Loss on Drying. The equipment needed includes: (1) analytical balance, capable of 0.0001 gram accuracy; (2) aluminum moisture dishes with covers, approximately x 15 mm (Fisher Scientific #08-722 or equivalent); (3) oven, gravity convection, maintained at 130 ± 2° C; (4) desiccators with indicating Drierite ®< (anhydrous CaSO 4 ) or other suitable desiccant; (5) crucible tongs, general purpose, approx. 9"; (6) small laboratory spatula or sponula. Several aluminum weighing dishes are conditioned in a 130 ± 2° C oven for 2 to 3 hours (number the tops and bottoms of each weighing dish before conditioning). Using a pair of tongs, the conditioned aluminum weighing dishes are then removed from the oven and placed in a desiccator containing suitable desiccant. The conditioned aluminum weighting dishes are allowed to cool for 30-60 minutes. In duplicate, using an analytical balance, the weight of an oven dried aluminum weighing dish and lid is obtained and recorded as "A". A 4-5 gram portion of the sample is transferred to the weighing dish. The dish is immediately covered and weighed. This weight is recorded as "B". The dish is placed, uncovered, in a 130 ±- 2 °C oven for 4- 6 hours. The dish is removed from the oven, immediately covered with the top, and placed into a desiccator. The dish is allowed to cool for 15-30 minutes. The dish is removed from the desiccator and accurately weighed. This weight is recorded as "C". Moisture content is calculated and reported to one decimal place in accordance with the following equation: % moisture = 100 − C − A × 100 / B − A (B-A) = sample weight before drying (C-A) = remaining residue weight after drying for four hours.

[0066] Alternately, an inert gas "purge" may be introduced into the micronization process so as to drive off moisture contained within the base granular starch so that any remaining moisture in the base granular starch is insufficient to gelatinize the starch. The moisture of the inert gas prior to and subsequent to introduction of the inert gas into the micronization apparatus may be compared so as to determine the degree to which the moisture of the micronized starch was reduced in producing the micronized starch.

[0067] Example 3: Measuring crystallization of micronized starches by X-Ray diffraction. Starches are measured by powder X-Ray diffraction. X-ray diffraction patterns are obtained with an X-ray diffractometer (Rigaku Miniflex) equipped with a sealed X-ray tube with Cu K α radiation (A = 1.5418 Å). The diffractometer is operated at 15 mA and 30 kV, and the spectra are scanned over a diffraction angle (2θ) range of 10° to 40° at a step size of 0.1° and a count time of 0.5 seconds. Crystallinity is calculated as the percentage of peak area to the total diffraction area.

[0068] Example 4: Measuring crystallization of micronized starches By retention Of birefringence. The morphology of this partially pregelatinized starch composition is observed using scanning electron microscope (SEM) (Fig. 1A-3C); and X-ray diffraction (Fig. 4-6). For microscopic analysis, approximately 0.5% starch powder is dispersed in water homogeneously and observed using a microscope under both light and polarized light. For SEM analysis, samples are mounted and vacuum-coated with gold. The SEM analysis is performed at 15 kV with a beam current of 2 X 10 -10< A. The distance to sample is set at 15 mm to achieve good image quality.

[0069] Example 5: Measuring gelatinization temperatures of micronized starches. Small particles of the starch are placed between a slide and cover slip and the sample is heated and cooled while being examined for its crystal structure. A small amount of the starch is dispersed in deionized water, placed on a glass slide, and covered with a cover slip. This sample is then heated from room temperature to 100° C at a rate of 5° C per minute using a Mettler Hot Stage in conjunction with the use of an Olympus Polarized Light Microscope fitted with a long working distance objective. Images are collected at specified intervals during the experiment to document the changes to the starch granules as the sample is heated. The gelatinization temperature is determined by observing the swelling of the starch granules. This results in a temperature range with an onset of gelatinization where granules are first observed to swell and a completion of gelatinization where no more swelling of the granules is observed.

[0070] Example 6: Measuring (heat of enthalpy) temperatures of micronized starches. Differential scanning calorimetry (DSC) measurements are performed in a Perkin-Elmer DSC-7 (Norwalk, Conn., U.S.A). The instrument was calibrated with indium. Samples of approximately 10 mg starch at a starch:water ratio of 1:3 are prepared and heated at 10° C / min from 50° C to 160° C. An empty stainless steel pan was used as a reference.

[0071] Example 7: Measuring peak viscosity of starches utilizing a Brabender viscometer at neutral pH. The peak viscosity of the starch of the instant application is determined using a Brabender viscoamylograph. A 97.4 g portion of the starch is mixed with 389.6 g of distilled water and added to the Brabender viscoamylograph bowl. The slurry is heated from 25° C to 92° C at a rate of 4° C / minute and held at 92° C for twenty minutes. The slurry is then cooled to 25° C at a rate of 1.5° C / minute. The results are shown in Figure 13.

[0072] Example 8: Measuring particle size and distribution of micronized starches. Particle size is measured using a LS 13 230, manufactured by Beckman Coulter (Indianapolis, IN) and incorporating Polarization Intensity Differential Screening (PIDS) technology together with a software package to provide a dynamic range of particle size measurement capabilities from 0.04 µm to 2000 µm. From the pull down manual of the software, the sample ID is entered the appropriate optical module to be used for the system to be measured is selected. A sequence of steps automatically follows: measuring offsets; alignment; background measurement; and measure loading. The instrument sounds a bell and displays measuring loading when ready to accept a sample. A diluted (approximately 1% solids) sample is introduced by drops into the sample reservoir and the changes in the measure loading are observed. This function measures the amount of light scattered out of the beam by the particles so as to determine an appropriate concentration of sample. When sizing particles without using PIDS an obscuration level of 8% to 12% is appropriate. When PIDS is used, a PIDS obscuration of 40% to 60% is recommended. A real part of index of refraction of 1.5 was used.

[0073] Example 9: Manufacture of a micronized starch-containing tablet. Formulations containing active ingredients were prepared for direct compression. The active ingredient, starch composition, and other ingredients (except lubricant) were mixed in a Turbula (Willy A. Bachofen AG Maschininfabrik, Switzerland, Type T2F) mixer for 15 minutes. The mixture was sieved through a 40 mesh (425 µm) sieve and the fraction passing through the screen is used. Lubricant was then added and the blend was mixed for another 1 to about 2 minutes. After mixing, the powders were stored in airtight containers until made into tablets. A single punch tablet press (Globe Pharma Model MTCM-1). Placebo starch tablets (containing 100% starch) were produced by this method. The single station tablet press was fitted with a 1.11 cm (7 / 16") standard concave punch and a corresponding die. A 500 mg portion of the powder was weighed (1% accuracy), fed into the die cavity, and compressed at 13 kN compression force. The compression time took about two to three seconds.

[0074] Example 10: Evaluation of crushing strength. Tablet hardness, indicated as tablet crushing strength, was determined for ten tablets, prepared using a Pharmatron (Model 6D) tablet tester. All tablets were prepared using 600 mg of powder on the single station tablet press, model MTCM-1 (Globe Pharma, Inc.) at 13.7 MPa compression force and using a ½ inch die cavity. The tablet press was fitted with 1.27 cm particle size punch die. Tablet crushing strength was measured on a Dr. Scheuniger Pharmatron Model 6D Tablet Tester (Pharmatron AG, Switzerland). Three tablets were tested from each sample.

[0075] Example 11: Preparation of a colloid with a micronized starch. Micronized starch (approximately 5 g) was gradually added into water (100 g) while agitating using a stirring bar for 5 to 15 minutes. After the micronized starch powder was fully dispersed, a colloidal system was formed which was milky and smooth in texture. This was designated as a colloidal stock. Approximately 10 mL of the colloidal stock was then mixed with Yoplait ®< yogurt (100 mL, General Mills, Minneapolis, MN) to form a colloidal dispersion.

[0076] Example 12: Evaluation of colloid stability. Micronized starch (approximately 5 g) is gradually added into water (100g) while agitating using a stirring bar for 5 to 15 minutes. After micronized starch powder was fully dispersed a colloidal system was formed which was milky and smooth in texture, designated as a colloidal stock. Approximately 10 mL of the colloidal stock was then mixed with Yoplait ®< yogurt (100 mL, General Mills, Minneapolis, MN) to form a colloidal dispersion. Using micronized Hi-maize ®< starch, micronized NOVELOSE ®< 330 starch, or micronized NOVELOSE ®< 480HA starch, potential dietary fiber formulations were obtained. Formulations are evaluated and stored in refrigerator at 4 °C. Results showed that formulations were smooth in texture and stable maintaining integrity and texture after 5 days without separation, while control formulations with non-micronized starches separated overnight.

[0077] Example 13: Preparation of micronized AMIOCA ®< starch, micronized HYLON ®< VII commercial high amylose corn starch, or micronized MELOJEL ®< dent corn starch. Dry grinding using an 100 AFG Fluidized Bed Jet Mill (20 lbs. capacity) was carried out at Pharmaceutical and Food Division, Hosokawa Micron Powder Systems, Summit, NJ. Samples of AMIOCA ®< starch, HYLON ®< VII starch, and MELOJEL ®< starch (FHI 0363), were procured. Each sample was divided further into an "oven dried" and an "as is" sample. The "oven dried" samples of AMIOCA ®< starch, HYLON ®< VII starch, and MELOJEL ®< starch were dehydrated prior to micronization. The "as is" samples of AMIOCA ®< starch, HYLON ®< VII starch, and MELOJEL ®< starch were not dehydrated prior to micronization. Each of the 5 samples (AMIOCA ®< starch, HYLON ®< VII starch, and MELOJEL ®< starch, in "oven dried" and "as is" form) were then jet-milled. A sufficient amount of dry nitrogen gas was utilized during jet milling, both to maintain a substantially oxygen-free environment during the jet milling process, and to drive off excess moisture liberated during the jet milling process itself and thereby substantially prevent gelatinization of the starch samples during the jet milling process. TABLE 1, reprinted below, provides a summary of the sizes and crystallinity of (a) base AMIOCA ®< starch, MELOJEL ®< starch, and (b) "as-is" jet-milled AMIOCA ®< starch, MELOJEL ®< starch, and HYLON ®< VII starch; and (c) "oven dried" AMIOCA ®< starch, MELOJEL ®< starch, and HYLON ®< VII starch. Table 1StarchAverage Particle Size Pre-Micronization (µm)Average Particle Size Post-Micronization (µm)Micronized Crystallinity (%)AMIOCA ®< Starch14.42.731.0MELOJEL ®< Starch18.33.427.4HYLON ®< VII Starch11.43.720.0

[0078] Example 14: Retention of crystallinity in micronized starches as measured by X-ray diffraction analysis. Using the analytical procedure of Example 3, micronized AMIOCA ®< starch (Fig. 4), micronized HYLON ®< VII starch (Fig. 5), and micronized MELOJEL ®< starch Fig. 6), retain most of the crystallinity of the granular starches from which they are derived, utilizing the micronized starches were produced in accordance with Example 13. Data summarizing crystallinity analysis is summarized in Table 2 below. Table 2StarchNative Crystallinity (%)Micronized Crystallinity (%)Retention of Crystallinity (%)AMIOCA ®< starch38.631.080.3MELOJEL ®< starch37.527.473.0HYLON ®< VII starch27.520.072.5

[0079] Example 15: Retention of crystallinity in micronized starches as measured by retention of birefringence. Fig. 7A (base granular AMIOCA ®< starch) vs. Fig. 7B (micronized AMIOCA ®< starch); Fig. 8A (base granular HYLON ®< VII starch) vs. Fig. 8B (micronized HYLON ®< VII starch); and Fig. 9A (base granular MELOJEL ®< starch) vs. Fig. 9B (micronized MELOJEL ®< starch) demonstrate that micronized starches retain most of the crystallinity of the granular starches from which they are derived, as analyzed using the procedure of Example 4.

[0080] Example 16: Gelatinization temperature of micronized starches. Using the procedure of Example 5, the gelatinization temperature of the micronized starches was determined. Micronized AMIOCA ®< starch gelation began at approximately 65 °C, close to the 65 °C gelation temperature of base granular AMIOCA ®< starch. Micronized HYLON ®< VII starch gelation began at approximately 72 °C, lower than the 88 °C gelation temperature of the base granular HYLON ®< VII starch. Micronized MELOJEL ®< starch gelation began at approximately 65 °C, close to the 65 °C gelation temperature of base granular MELOJEL ®< starch. Table 3SampleGelatinization temp (native).Gelatinization temp (micronized),AMIOCA ®< starch65 °C65 °CHYLON ®< VII starch88 °C72 °CMELOJEL ®< starch66 °C66 °C

[0081] Example 17: Heat of enthalpy of micronized starches. Using the protocol outlined in Example 6 above, the heat of enthalpy of the micronized starches was measured. These data are also shown in Fig. 10 (AMIOCA ®< starch); Fig. 11 (HYLON ®< VII starch), and Fig. 12 (MELOJEL ®< starch). Table 4 below demonstrates that micronized starches produced in accordance with Example 13 exhibit decreased heat of enthalpy as compared to base granular starches. Table 4StarchOnset Temp.Peak Temp.Peak HeightEnd Temp. (°C)AreaEnthalpyTo (°C)Tg (°C)(mW)(J / g, db starch)(mJ)(ΔH)AMIOCA ®< starch (control)66.51974.6143.229683.182214.30622.859micronized AMIOCA ®< starch) (dried)64.69875.9521.732486.124151.92215.858micronized AMIOCA ®< starch (as is)65.4975.2831.873187.294161.66317.244HYLON ®< VII starch(control)70.04085.3091.3169110.945282.98830.025micronized HYLON ®< VII starch (as is)65.89997.3321.0144112.717245.08125.503micronized HYLON ®< VII starch (dried)62.37097.6681.038997.668270.83828.183MELOJEL ®< starch (control)69.10873.9514.588079.968205.34321.638micronized MELOJEL ®< starch (as is)60.97271.6061.148680.40884.9878.904micronized MELOJEL ®< starch (dried)63.33469,9371.356281.254123.9481 13.217

[0082] Example 18: Peak viscosity measurements of micronized starches. Using the experimental procedure set forth in Example 7 above and utilizing the micronized starches produced in accordance with Example 13, the peak viscosity was determined as shown in Fig. 13. This demonstrates that micronized AMIOCA ®< starch and MELOJEL ®< starch exhibit decreased peak viscosity as compared to the base granular starches.

[0083] Example 19: Particle size and size distribution of micronized starches. Using the particle size analysis outlined in Example 8 above, the micronized starches prepared in Example 13 were measured. The results are found in Table 1 and in Fig. 15A, 15B, and 15C. Starch powder (about 0.1 g) was added into a 1 oz jar, and then was dispersed by agitation in distilled water. Starch suspension was then immediately introduced to the test chamber of the LS 13 320 for measurement. The sizes of base granular starch powders were also determined. Table 5 below gives the mean, median, and distribution of particle sizes for a variety of base granular starch powders. Table 5StarchesMean (µm)Median (µm)Distribution<25%<50%<75%Rice7.66.14.06.18.9Normal Maize13.813.110.613.916.9Tapioca15.115.011.015.018.4Waxy Maize15.515.211.715.218.7Wheat16.115.39.515.321.5Barley17.717.613.517.521.6Banana26.926.717.026.735.8Pea33.931.325.931.339.0Potato41.239.528.139.653.6

[0084] Example 20: Measurement of the crushing strength of tablets containing micronized starch. Table 6 below illustrates the results of tablet preparation and crushing strength analysis undertaken in accordance with the procedure outlined in Examples 10 and 11 above. The micronized starches prepared in accordance with Example 13 were compared to various industry standard tablet materials (MCC AVICEL ®< ; UNI-PURE ®< starch; etc.) The results are shown below, for tablets prepared using compression strength of 1000-3000 psi; and are further illustrated in Fig. 14A, Fig. 14B, and Fig.14C. Table 6SampleMoisture (%)1000 psi (kPa)2000 psi (kPa)3000 psi (kPa)MCC AVICEL PH 1025.7516.231.744.5UNI-PURE CD2 starch8.623.07.414.6UNI-PURE CD-15 starch10.051.74.68.0Starch 1500 Colorcon7.30N / AN / AC*Pharmgel DC 9300 (Cargill)10.12.29.414.4MELOJEL ®< starch11.181.2N / AN / AAMOICA ®< starch8.91.1N / AN / AHYLON ®< VIII starch9.71.4N / AN / AMELOJEL ®< micronized starch6.036.712.525.6AMOTGA ®< micronized starch6.855.512.019.6HYLON ®< VII micronized starch6.392.410.213.9MELOJEL ®< micronized starch14.139.528.323.7AMOICA ®< micronized starch14.5812.032.845.2HYLON ®< VII micronized starch15.7216.541.343.7

[0085] Example 21: Colloid stability analysis: Using the procedures of Examples 11 and 12, colloids were made from the micronized starches of Example 13. Micronized HYLON ®< VII starch showed much improved stability in ENSLTRE ®< from Abbott, while the base granular control precipitated out from ENSURE ®< after 8 hours.

[0086] Example 22: Measurement of the degree of polymerization (DP) of the micronized starches. The intrinsic viscosity [η] of starch solutions were measured at 23°C by using a U-shape capillary viscometer (CANNON Instrument Co. 200W298) in 90% DMSO in water. The Solomon-Ciuta equation was used to calculate [η]: [η] = [2(η sp - ln η r )] 0.5< / c. The Mark-Houwink equation gave relation between intrinsic viscosity [η] and the molecular weight Mw: [η] = K(Mw) α< . The value of the Mark-Houwink parameter K of 0.59 is taken from Millard et al. Cereal Chemistry, 1997, 74 (5), 687-691, which used light scattering methods to determine Mw. The value of the Mark-Houwink parameter α of 0.31 is that of a compact hydrodynamic starch conformation. The degree of polymerization (DP) of each starch was calculated as: DP = (Mw - 18) / 162. Table 7 below illustrates the results of Mw and DP analysis undertaken in accordance with this procedure. The micronized starches prepared in accordance with Example 13. Table 7Starchrun[η] (mL / g)Mw (10 6< )DP (10 3< )micronized AMIOCA ®< starch) (dried)116579486micronized AMIOCA ®< starch) (dried)216984519micronized MELOJEL ®< starch (dried)3184111688micronized MELOJEL ®< starch (dried)416883515micronized AMIOCA ®< starch (as is)5199144888micronized MELOJEL ®< starch (as is)615564397micronized MELOJEL ®< starch (as is)714451314micronized HYLON ®< VII starch (dried)884955micronized HYLON ®< VII starch (as is)9891065

Claims

1. A micronized starch with an average particle size as assessed by Polarization Intensity Differential Plus Electric Light Scattering according to the method used in Example 8 of the specification of less than 5 µm and a degree of polymerization as determined according to the method in Example 22 of the specification of greater than 100, wherein the micronized starch exhibits at least 20% of the crystallinity as determined by X-ray diffraction of the base granular starch according to the method used in Example 3 of the specification, wherein the micronized starch has an average particle size of at least 20% less than the average particle size of the base granular starch and wherein the micronized starch is obtained by a method comprising the steps of: a) dehydrating a base granular starch to a moisture content of less than 5% on a w / w basis, and b) micronization of the dehydrated base granular starch in an environment containing less than 5% oxygen in a v / v basis to result in a micronized starch, wherein the micronized starch has a moisture content of no greater than 5% on a w / w basis of the base granular starch as determined according to the method used in Example 2 of the specification and wherein the starch is sourced from corn, pea, potato, sweet potato, banana, Barley, wheat, sago, oat, amaranth, tapioca, arrowroot, canna, sorghum, and waxy or high amylose varieties thereof.

2. The micronized starch of claim 1, wherein the micronized starch exhibits at least 60% of the crystallinity of the base granular starch.

3. The micronized starch of any one of claims 1 or 2, wherein the micronized starch exhibits at most 90% of the crystallinity of the base granular starch.

4. The micronized starch of any one of claims 1 to 3, wherein the base granular starch is a cereal starch.

5. The micronized starch of claim 4, wherein the base granular starch is a corn starch.

6. The micronized starch of any one of claims 1 to 5, wherein the melting enthalpy as determined by DSC of the micronized starch according to the method in Example 6 of the specification is at least 50% of the melting enthalpy of the base granular starch.

7. The micronized starch of any one of claims 1 to 6, wherein the gelatinization temperature of the micronized starch is no more than 16 °C different than the gelatinization temperature of the base granular starch, wherein gelatinization temperature means the onset temperature of gelatinization as determined according to the method in Example 5 of the specification.

8. The micronized starch of any one of claims 1 to 7, wherein the peak viscosity as determined according to the method in Example 7 of the specification of the micronized starch is not greater than 90% of the peak viscosity of the base granular starch.

9. The micronized starch of any one of claims 1 to 8, wherein the degree of polymerization of the micronized starch is greater than 1,000.

10. The micronized starch of claim 9. wherein the degree of polymerization of the micronized starch is greater than 10,000.

11. A tablet comprising the micronized starch of claim 1 and at least one other pharmaceutically acceptable ingredient.

12. The tablet of claim 11, wherein the tablet is characterized by a crushing strength of at least 20 kPa at a compression pressure of 20.68 MPa [3000 PSI] in a tablet consisting only of the starch, wherein crushing strength means the force necessary to fragment a dosage form as determined by measurement on a Dr. Scheuninger Pharmatron Model 6D Tablet Tester according to the method of Example 10 of the specification.

13. A method of reducing starch particle size comprising the steps of: a) dehydrating a base granular starch to a moisture content of less than 5% on a w / w basis, and b) micronization of the dehydrated base granular starch in an environment containing less than 5% oxygen in a v / v basis to result in a micronized starch; wherein the micronized starch has a moisture content of no greater than 5% on a w / w basis of the base granular starch as determined according to the method of Example 2 of the specification; wherein the micronized starch comprises an average particle size as assessed by Polarization Intensity Differential Plus Electric Light Scattering according to the method used in Example 8 of the specification of less than 5 µm; wherein the degree of polymerization as determined according to the method in Example 22 of the specification of the micronized starch is greater than 100; and wherein the micronized starch exhibits at least 20% of the crystallinity as determined by X-ray diffraction of the base granular starch according to the method used in Example 3 of the specification, wherein the micronised starch has an average particle size of at least 20% less than the average particle size of the base granular starch, and wherein the starch is sourced from corn, pea, potato, sweet potato, banana, Barley, wheat, sago, oat, amaranth, tapioca, arrowroot, canna, sorghum, and waxy or high amylose varieties thereof.

14. The method of claim 13 wherein the environment is comprised of inert gas.