Microcapsules

Abstract

The present invention relates to microcapsules, and more particularly to microcapsules where an aqueous bead or beads comprising the active ingredient is encapsulated in or by a hydrophobic shell matrix. The present invention relates also to novel methods for preparing the microcapsules according to the invention, as well as to the use of the microcapsules of the present invention. A microcapsule of the present invention comprises a solidified hydrophobic shell matrix, an encapsulated aqueous bead or beads which is / are encapsulated in or by the solidified hydrophobic shell matrix, and an active ingredient or active ingredients dissolved or incorporated in the encapsulated aqueous bead or beads.

Description

FIELD OF THE INVENTION [0001] The present invention relates to microcapsules, and more particularly to microcapsules where an encapsulated aqueous bead or encapsulated aqueous beads comprising the active ingredient or active ingredients is / are further encapsulated in a hydrophobic shell matrix. The present invention relates also to novel methods for preparing the microcapsules according to the invention, as well as to the use of the microcapsules of the present invention. BACKGROUND OF THE INVENTION [0002] U.S. Pat. No. 5,204,029 discloses a process for preparing edible microcapsules which contain a multiplicity of liquid cores. In the process, a water-in-oil emulsion, with the active ingredient dissolved in an inner aqueous phase, is spray cooled, which causes the solidification of the fat phase and the entrapment of the aqueous phase as minute droplets dispersed in a microcapsule. This process, however, leads to very unstable microcapsules from which the water phase migrates from ...

AI Technical Summary

Benefits of technology

[0025] An advantage of the present invention is that the release of the active ingredient(s) from the microcapsules can be controlled. The release rate of a water-soluble active ingredient in a conventionally spray cooled fat matrix microcapsule is usually not controlled by the melting of the fat matrix but rather by the diffusion of water into the microcapsule and subsequent migration of the active ingredient outside the microcapsule. The release rate of the active ingredient from conventional spray cooled microcapsules is usually very high. Typically, the release rates of the active ingredients are in the range of approximately 80% release within 15 minutes, depending on the nature of the encapsulated active ingredient. The novel and inventive microcapsules of the present invention have a much lower rate and / or sustained release of the active ingredients since most of the active ingredients are released when the solidified hydrophobic shell matrix is actually “melted”. The release of the active ingredients from the microcapsules of the present invention can be controlled and the release can be initiated in various ways, for example by heat treatment, e.g. by heating, such as in a microwave oven, or by freezing, by stress treatment or by any other suitable process. The release of the active ingredients from the microcapsules of the present invention can also be sustained or it can happen very slowly.

[0026] Another advantage of the microcapsules of the present invention is that the stability of the microcapsules is improved. Since the active ingredients are dissolved or incorporated in encapsulated, preferably in gelled or cross-linked aqueous beads, which are further encapsulated in or by the solidified hydrophobic shell matrix, the aqueous phase is not able to migrate or evaporate to the shell matrix or outside the shell matrix.

[0027] An advantage of the microcapsules of the present invention compared to the microcapsules of the prior art, for example microcapsules prepared according to the cited references of Lee et al, Dinsmore et al, Mofidi et al or Wong et al, is that the hydrophobic phase is used to form a further encapsulation, thus forming microcapsules, where the active ingredient(s) is / are first encapsulated inside an aqueous bead and then further encapsulated in a hydrophobic phase.

[0028] The new improved properties of the microcapsules of the present invention enable the use of the microcapsules of the present invention in a wide variety of applications, for example in various applications in the food / feed or pharmaceutical fields.

[0029] Yet another advantage of the method of the invention is that it enables a high production capacity to be achieved while the costs are still low.

[0030] In the present specification in one aspect the term “encapsulated in or by the solidified hydrophobic shell matrix” may be taken to mean “encapsulated in the solidified hydrophobic shell matrix”. In another aspect the term “encapsulated in or by the solidified hydrophobic shell matrix” may be taken to mean “encapsulated by the solidified hydrophobic shell matrix”.

Problems solved by technology

This process, however, leads to very unstable microcapsules from which the water phase migrates from the inner part of the microcapsule to an outer part.

This further results in the condensation of the water on the wall of a container.

The process is only suitable for liquids or slurries, and the products of the process are large beads having meltable coatings, such as fats or waxes.

However, the microcapsules containing a single liquid droplet as a core are very susceptible to rupture.

A disadvantage of the microcapsules or spheres prepared according to the cited references of Lee et al, Dinsmore et al, Mofidi et al or Wong et al is that the microcapsules are only single encapsulated microcapsules and the hydrophobic phase is discarded after the microcapsules have been prepared.

A problem associated with the prior art microcapsules containing only one single liquid phase droplet is that they are very susceptible to rupture.

The shell material can break for example during storing or handling of the microcapsules, and this causes the liquid of the whole inner phase to run free.

This results in a sticky mass, and the microcapsules are no longer in the form of a free flowing powder.

However, this process still results in very unstable microcapsules from which the water phase migrates from the inner part of the microcapsule to the outer part and further outside the capsule.

This further results in the condensation of water on the wall of the container.

Another problem associated with the microcapsules according to the cited U.S. Pat. No. 5,204,029 is that the release of the active ingredient cannot be controlled in the microcapsules.

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