Title:  Flexible gelatin free encapsulation material useful for pharmaceuticals, paint balls and other formulations

United States Patent:  6,210,709

Assignee:  Elementis Specialties, Inc. (Hightstown, NJ)

Filed:  March 24, 1999

A flexible capsule formed from a modified starch free of animal based gelatin. The invention provides a novel capsule defining a closed interior chamber, the capsule being formulated from a composition which is free of animal based gelatin comprising at least one plant based starch having been modified to have gelatin like properties; and a paint ball formulation, drug, vitamin, perfume or bath product contained within the capsule.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

The flexible capsules according to the present invention are free of animal based gelatin. In place of the gelatin, a starch is utilized which has been modified to have gelatin like properties. The flexible capsules include, for example, paint balls, pharmaceutical gelatin capsules, vitamin/health formulations using capsules, perfume/cosmetic/bath and gel encapsulated products.

Starches vary largely in the number of the repeating unit (n) in the polymer, which to a major extent depends on the source of the starch. Starch is normally composed of about 25% amylose and 75% amylopectin. Amylose is currently considered by scientists as a mixture of linear and slightly branched molecules whereas amylopectin is considered a densely branched, high molecular weight molecule. In some cereal starches, the amylose content can be as low as 0-1% as in waxy barley, waxy sorghum, and waxy corn and can be as high was 50-70% in some corn hybrids. Starch is often described as a repeating polymer of glucose units linked together by glycosidic bonds.

Starch is a polysaccharide obtained from plants, of which wheat, corn, potato, tapioca and rice are common commercial sources. Without the various modifications discussed herein, starch is a white, semi-crystalline, tasteless powder often in granule form. When starch is mixed with hot water in sufficient amount, such as at a temperature of 65^oC. or higher, irreversible gelatinization can occur. Swelling of starch granules can be induced at lower temperatures by the addition of such compounds as formamide, formic acid, and strong bases and certain metallic salts. A large number of pure starch grades are available including those commonly referred to as commercial, powdered, pearl, laundry, technical and edible. Preferably, edible starches are modified and used to form the flexible capsule.

The starch must be modified to have gelatin like properties. Gelatin like properties include the combination of flexibility and strength when formed into a capsule or film. Based on the disclosure provided herein, one skilled in the art will easily be able to formulate and select modified starches which are suitable for forming flexible capsules according to the present invention. As shown in the Examples, by using animal based gelatin as a control, those modified starches which provide a film having at least 80% of both flexibility and strength of the control gelatin film are suitable (index of at least 4). Preferably, a modified starch is selected which provides a film having at least 90% of both flexibility and strength of the control gelatin film. Combinations of modified starches with film strengtheners such as polyvinyl alcohol can be used to provide the required combination of flexibility and strength.

Examples of suitable modifications for modifying the strength and flexibility characteristics of starches include cross-linking, substituting functional groups on the polymer chain, oxidizing, and acid-thinning. Preferably, the starch is modified by well known oxidizing techniques. The Code of Federal Regulations, which is incorporated herein by reference, describes in detail starches and modified starches intended for industrial or food applications. For example, 21 CFR 172.892 describes modification of starch for food use and 21 CFR 178.3520 covers the modification of starch for industrial applications. Starch-based polymers are reaction polyols derived from a reaction, using catalysts, of a starch with dibasic acids and hydrogen-donating compounds dissolved in a water slurry; the slurry is subjected to high temperatures and pressures, yielding a low-viscosity polymer in an aqueous solution. Molecular rearrangement takes place, and the starch-derived polymer formed can be very different from natural starch in structure. The polymer can be further reacted with acids, bases, and cross-linking agents.

A preferred modified starch is derived from wheat produced by Rheox Inc. bearing the commercial designation EA-2865. EA-2865 is an instant or pregelatinized starch obtained by physical modification of wheat starch.

The modified starch should be present in an amount of from about 20 to about 80% by weight, preferably about 20 to about 50% by weight, based on the total weight of the capsule formulation.

In a preferred embodiment, the flexible capsules of this invention also contain a plasticizer and water.

Any conventional plasticizer can be utilized. Examples of suitable plasticisers include glycerin, xylitol, sorbitol, polyglycyerol, non-crystallizing solutions of sorbitol, glucose, fructose and glucose syrups with varying equivalents. A commercial plasticizer is ANIDRISORB, which is a proprietary mixture of sorbitol, sorbitans, maltitol and mannitol. Most preferably, the plasticizer is glycerin.

The plasticizer should be present in an amount of from about 5 to about 50% by weight, preferably about 10 to about 40% by weight, based on the total weight of the capsule formulation.

Water should be present in an amount of from about 10 to about 70% by weight, preferably about 20 to about 60% by weight, based on the total weight of the capsule formulation.

The capsule formulation can also contain conventional additives for use in capsules, such as colorants, flavors, aromas, and polymers. If desired, unmodified starch can be utilized in combination with the modified starch.

The capsule of this invention can be produced by a variety of known encapsulation processes. For example, the capsule can be prepared according to the coacervation process in which material to be encapsulated is dispersed in the aqueous capsule forming solution. In this procedure, a non-solvent for the modified starch and an electrolyte is added or a pH change or a pressure change is effected to make the capsule. Examples of this coacervation process are described in U.S. Pat. Nos. 4,777,089, 3,943,063 and 4,978,483, all three of which are incorporated herein by reference.

The capsule of the invention also can be prepared by extrusion nozzles as taught in U.S. Pat. Nos. 3,310,612, 3,389,194 or 2,799,897 and GB 1,390,503. In these processes, the material to be encapsulated is extruded through the inert orifice of the nozzle. Simultaneously, the capsule forming solution is extruded through the outer orifice of the nozzle to form a uniform coating on the surface of the material to be encapsulated. The capsule is then formed by breaking the coextrudate at the end of the nozzle orifice by air, centrifuge force, blade or carry fluid to form droplets which are hardened in a nonsolvent of the capsule forming material.

U.S. Pat. No. 5,001,880, incorporated herein by reference, teaches a method for forming paint balls in which the capsule is formed as two parts and then molded together.

The above described processes are not intended to be limiting.

The capsule can be used in place of known gelatin based capsules. For example, when forming paint balls, the capsule according to the present invention can be used in place of the gelatin capsule disclosed in U.S. Pat. No. 5,393,054, which is incorporated herein by reference. When paint balls are formed, the encapsulated paint material preferably comprises about 1 to about 65% polyethylene glycol, about 25 to 45% starch, dye and water.

Food grade modified starch can be utilized such that the capsule is suitable for use in pharmaceutical and vitamin applications. The formation of pharmaceuticals and vitamins is well known in the art and one skilled in the art will be able to utilize the gelatin free formulations described herein in for pharmaceutical and vitamin applications.

Claim 1 of 21 Claims

What we claim:

1. An encapsulated material comprising:

a capsule defining a closed interior chamber, said capsule being formulated from a composition which is free of animal based gelatin comprising at least one plant based starch having been modified to have flexability and strength similar to gelatin wherein said modified starch comprises a pregelantized, oxidized wheat starch; and

a material contained within said capsule.

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