Zeaxanthin (ZX) or other medically or commercially important carotenoids can be prepared in
microcrystalline form, in an oily carrier liquid, to increase their
bioavailability following oral
ingestion. Initial
processing is carried out to prepare a “rough” or “coarse-grained”
carotenoid preparation containing relatively large particles of the ZX or other
carotenoid, in a suitable form such as a lyophilized stable
powder. The coarse-grain preparation is dissolved in a suitable
solvent such as
tetrahydrofuran, and mixed with a carrier liquid comprising a digestible oil (such as a
vegetable oil) and an emulsifying agent. The resulting oil-and-
solvent mixture is injected, along with
inert gas such as
nitrogen, into a
vacuum chamber, where a suitable vacuum and temperature combination is used to remove the
solvent in a rapid “flash” manner which does not give the
carotenoid crystals time to grow larger through accretion or aggregation. This generates a
microcrystalline suspension containing very
small particles of the ZX or other cartenoid, in the oily liquid carrier. This product can be further processed if desired, or it can be loaded directly into watertight capsules for oral
ingestion. Tests on human volunteers have confirmed that the
bioavailability of this
microcrystalline form is substantially higher than prior art preparations having larger particles of the carotenoid.