Plastic and nonmetallic article shaping or treating: processes – Encapsulating normally liquid material
Patent
1995-11-11
1997-08-26
Mullis, Jeffrey C.
Plastic and nonmetallic article shaping or treating: processes
Encapsulating normally liquid material
424451, 435243, 4352551, 4284022, 42840224, A61K 950
Patent
active
056607695
DESCRIPTION:
BRIEF SUMMARY
This invention relates to methods for encapsulating substances.
It is known to encapsulate various substances in microcapsules which occur naturally or which can otherwise be referred to as biocapsules. U.S. Pat. No. 4,696,863, GB-A-2 162 147 and EP-A-0 242 135 disclose bioencapsulation in such organisms as yeast cells (which may be used alive or dead), microfungi, bacteria and algae.
Difficulties are encountered when trying to encapsulate certain substances. GB-A-2 234 901 discloses a method for encapsulating water-insoluble substances which are, however, soluble in liquid ammonia, which is used as the carrier by which the substance is carried by diffusion into the cell.
It is now found that even some water-soluble substances cannot effectively be encapsulated using an aqueous solution, because the substances pass out of the capsule as easily as they are passed in, and the present invention provides a generalised method which can be used with such and other difficult-to-encapsulate substances.
The invention comprises a method for encapsulating a substance in a biocapsule comprising passing a solution into the biocapsule, then effecting a change in the biocapsule/solution system such that the substance remains encapsulated while a solvent escapes.
The change may comprise a physical change, which may involve an increase in solution concentration, at least as a proportion of solution saturation level, within the capsule. It may involve a decrease in solubility of the substance in the solution within the capsule, as by cooling, and the substance may precipitate from a saturated solution within the capsule.
The solvent may however evaporate from the capsule, leaving behind the substance.
The solution may swell the biocapsule sufficiently to pass through the capsule wall to enter the capsule, and the change may then comprise a reversal of the capsule swelling sufficient to trap molecules of the substance but allow solvent molecules to pass out.
The change may comprise a chemical change. A first solution may be passed into the biocapsule, then a second solution gassed into the biocapsule which reacts with the first solution to yield the substance in the biocapsule in such manner as to remain encapsulated.
The first and second solutions may comprise different solutes, or different solvents, or both.
Liquid ammonia, such as has been proposed for water-insoluble substances as noted above, is found now also to be useful for certain water-soluble substances which, however, cannot be encapsulated from aqueous solution for the reason stated above. It is especially suitable for use with some acids and in particular with amino acids.
Amino acids may be in the salt form, preferably the ammonium salt, and may be encapsulated alone or together with other ingredients, for example fish oils. In addition to increasing the nutritional value of such capsules, fish oils also protect the amino acids from leaching out of the capsules. For example, the amino acid histidine may be encapsulated as follows: liquid ammonia 150 g. Yeast 25 g, is added slowly with continuous stirring. After 5 minutes the mixture is poured into absolute ethanol 600 ml and the resultant mixture filtered and washed with absolute ethanol under gentle suction. The filter cake is spread out and allowed to dry in air. yeast after this process was carried out.
Materials encapsulated in starch or yeast granules, for example, may be used as animal feeds, in particular for ruminant feeds where the capsule coating would protect its contents, ie. amino acids, during passage through the first stomach (rumen), where normally they would be destroyed, until they entered the second stomach (abomasum) where they may be absorbed intact.
In addition, such capsules may be used as feed for fish larvae, and the content of the capsules could be tailored specifically for the particular needs of each stage of the growing larvae.
Many other substances may be encapsulated, for example: degree of digestion, for example, in washing powders; a dust form rather than the commonly used pel
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Graham Samuel Gordon
Sagar Anthony John Grant
Sagar Brian Frederick
Wragg Reginald Trevor
CPC International Inc.
Mullis Jeffrey C.
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