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J Sep Sci. 2012 May;35(9):1183-9. doi: 10.1002/jssc.201101109.

Isolation of bitter acids from hops (Humulus lupulus L.) using countercurrent chromatography.

Author information

1
Metagenics, Inc., Gig Harbor, WA 98332, USA. clintondahlberg@metagenics.com

Abstract

Commercially available hops (Humulus lupulus L.) bitter acid extracts contain a mixture of three major congeners (co-, n-, and ad-) in addition to cis/trans diastereomers for each congener. Individual isomerized α-acids were obtained by the consecutive application of two separate countercurrent chromatography methods. First, individual isomerized α-acid congeners as a mixture of cis/trans diastereomers were obtained using a solvent system consisting of hexane and aqueous buffer. The second purification, capable of separating cis/trans diastereomers, was accomplished using a quaternary solvent system; an alternative procedure using β-cyclodextrin followed by countercurrent chromatography was also investigated. The NaBH(4) reduction of the purified isomerized α-acid compounds followed by countercurrent chromatography purification resulted in individual ρ iso α-acids (>95%). Similarly, catalytic hydrogenation of the purified isomerized α-acid compounds followed by countercurrent chromatography purification produced individual tetrahydro isomerized α-acids (>95%). Reported herein is a widely applicable approach that focuses on three critical variables--solvent system composition, pH, and buffer-to-sample ratio--that enable the efficient purification of individual bitter acids (≥95%) from commercially available hops extracts.

PMID:
22689494
DOI:
10.1002/jssc.201101109
[Indexed for MEDLINE]

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