Instant water dissolvable encapsulate and process

Details Instant water dissolvable encapsulate and process Instant water dissolvable encapsulate and process

2001-09-26

2003-04-01

Hartley, Michael G. (Department: 1616)

Drug, bio-affecting and body treating compositions

Preparations characterized by special physical form

Capsules

C424S401000

Reexamination Certificate

active

06541030

ABSTRACT:

FIELD OF THE INVENTION
The present invention relates to water soluble microcapsule compositions, processes for their preparation and their uses in various applications including the food, nutriceutical and pharmaceutical industries.
BACKGROUND OF THE INVENTION
Capsules have been developed to serve a variety of functions. One general purpose of encapsulation is to preserve or isolate the core material from its environment until an appropriate time or condition is present. In these situations, the core material is protected from the environment by the shell. Such protection is not always easily achieved since the core material may be able to penetrate or diffuse through the shell. On the other hand, use can be made of the “leaky” feature of some shells to control the release rate of the core material into the surrounding environment.
Encapsulation can protect compounds from environmental conditions such as temperature, pH, or chemically reactive surroundings such as oxidizing and reducing environments. Such oxidizing and reducing environments may consist of chemicals to which the capsule has been added. In other cases, it is desirable to encapsulate certain chemical compounds not only for protection of the core but also to protect or shield the external environment from reaction with the chemical compound forming the core. One common example of this use for encapsulation is the masking of the taste and/or odor of a chemical composition. In such a case, encapsulation may offer protection against detection of a bitter, toxic or otherwise undesirable taste or odor. Encapsulation of skin and respiratory irritants and toxins is one important way to protect the handlers of such materials from exposure.
A variety of micro-encapsulation methods and compositions are known in the art. These compositions are primarily used in food, agricultural and pharmaceutical formulations, for example, to flavor products, to mask the taste of bitter drugs, formulate prolonged dosage forms, separate incompatible materials, protect chemicals from moisture or oxidation, or modify the physical characteristics of the material for ease of handling and/or processing.
Many liquids, such as flavors and fragrance oils for example, contain a mixture of volatile alcohols and aromatics, which evaporate when exposed to even minimal heat. Indeed, many such substances often lose as much as 45% of their original weight during the encapsulation process due to volatilization. Such losses are wasteful and expensive. Additionally, resulting end-products of these methods often taste less poignant or smell less desirable than the original liquids.
Many of the techniques used to microencapsulate involve the polymerization or setting of a resin, such as a polyurea, to form the outer shell of the microsphere. Typical pharmaceutical encapsulation compositions include, e.g., gelatin, polyvinyl alcohol, ethylcellulose, cellulose acetatephthalate and styrene maleic anhydride. See Remington's Pharmaceutical Sciences, Mack Publishing Co., Easton Pa. (1990). Other techniques use primarily fats, waxes or polymers to film form the outer shell.
The use of fats as a retention media for volatiles is disclosed in U.S. Pat. No. 3,949,094 of Johnson, et al. issued Apr. 6, 1976, wherein volatile flavorings, seasonings, colorants, flavor enhancers and the like are blended with lipoidal material under super atmospheric conditions for subsequent handling or conversion into particulates by a spray chilling process. While retention of the volatiles within fat under pressure reduces vaporization before processing, excessive losses are still experienced during the Johnson spray chilling encapsulation method.
Redding, U.S. Pat. No. 5,460,756 describes the entrapping of liquids within a stable lipid or wax shell using pressure pulse techniques.
Lim, et al., U.S. Pat. No. 4,389,419 describes the formation of an emulsion consisting of a continuous phase aqueous solution of an alkali metal alginate, and optionally, water-soluble alcohol-insoluble filler such as a polysaccharide, and a dispersed phase of an oleophilic substance. The emulsion thus produced is then formed into droplets, which are immersed into an alcoholic solution of multi-valent cations, to produce a water-insoluble shape-retaining alginate matrix filled with precipitated polysaccharide and enclosing plural oil droplets.
Another markedly different approach employed for encapsulating vitamin or mineral nutrients, such as thiamine, is described by Hall, et al., U.S. Pat. No. 4,182,778 issued Jan. 8, 1980. Hall, et al. describe encapsulation by fluidizing the nutrient in a gaseous stream and contacting the nutrient with finely atomized droplets of a coating solution.
Boyle et al, U.S. Pat. No. 5,925,381, describe the microencapsulation of oleophilic substances by forming an emulsion out of the oleophilic substance and a polymer, and then using heat setting and/or cross-linking of the polymer to encapsulate the oleophilic composition. This process is then repeated with a second polymer or third polymer, and with or without cross-linked via the same or different mechanism to further protect the oleophilic substance.
U.S. Pat. No. 4,353,962 discloses the in-flight encapsulation of materials for herbicidal, insecticidal and the like uses, for example, with film-forming polymers, in particular acrylic polymers from aqueous emulsion that may include a surfactant. The emulsion is spray dried onto the target in the form of a material encapsulated in a hardened x-linked acrylic encapsulating shell.
There is a need in the art for a microcapsule encapsulating active ingredients such as pharmaceuticals, herbicides, pesticides, flavors and fragrances, where the encapsulating shell is highly water soluble. Such a microcapsule would function to protect the encapsulated core material until placed into contact with an aqueous environment, when the active would be released instantly into the aqueous environment.
REPORTED DEVELOPMENTS
Water soluble microcapsules have been reported in the patent literature for many years for the preparation of storage stable flavors and fragrances using starch materials of one type or another as water soluble shell materials.
U.S. Pat. No. 3,455,838 discloses encapsulating lemon oil in a shell consisting of a dextrinized starch acid-ester of a substituted dicarboxylic acid. The encapsulate is prepared by mixing the lemon oil and an aqueous solution of the modified dextrin, passing it through a colloid mill, and spray drying the emulsion.
U.S. Pat. No. 3,499,962 discloses the encapsulation of water insoluble materials with a high amylose-containing starch material by mixing the insoluble material with an amylose solution at a temperature above 140 degrees F. and spray drying the mixture.
U.S. Pat. No. 5,370,881 discloses a micronized dispersion of flavor oil in a matrix of water soluble sucrose derivative such as isomalt. The matrix is formed in a flash flow process and the product is described as providing a rapid release of flavor.
U.S. Pat. No. 5,976,575 discloses encapsulated carotenoid oil prepared by emulsifying the oil with an aqueous solution of sugar, a starch encapsulating agent and an anti-oxidant, homogenizing the dispersion using a high pressure homogenizer and spray drying the resulting finely dispersed emulsion.
The use of other hydrophilic polymers such as cellulosic materials as the outer shell has also been described for encapsulated flavors as well as drug substances.
U.S. Pat. No. 3,664,963 discloses a lemon oil microcapsule encapsulated in a water soluble shell prepared from water soluble hydrophilic polymers including water soluble cellulosic compounds such as alkali cellulose, cellulose ethers and esters. The capsules are prepared from an oil in water emulsion of the lemon oil and polymer, which may include other ingredients including anti-oxidants and surfactants. The emulsion may be dispersed by a pressure homogenizer, and sprayed over polyethylene glycol to remove the water from the water soluble shell. The resulting capsules are coated with a laye

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