Analysis of Hop Extracts by Simplified Counter-Current Distribution Methods

Verzele, M.; Claus, H.; Dyck, J. Van

doi:10.1002/j.2050-0416.1967.tb03016.x

Cited by 27 publications

(5 citation statements)

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“…:m/z(%) 361 (M-1, 100), 362 (22), 363 (3), 195 (50). HRMS (ESI-): m/z calcd for C21H29O5 (M-1) -1 : 361.2020; found: 361.2016 (-1.7 ppm).…”

Section: Ms (Esi-)mentioning

confidence: 99%

“…The individual homologues of humulone 1 have historically been isolated from hops or hop extracts by countercurrent distribution techniques. 1a 22 Alternatively, racemic co-humulone ( 1b ) has been synthesized from phloroglucinol precursors, although the overall yields are low. 23 We found it more expedient to obtain 1a and 1b directly from supercritical CO 2 hop extracts by a combination of fractional extraction, crystallization techniques and preparative C18 chromatography (Scheme 1 ).…”

Section: Table 1 Reaction Conditions For the Isomerizat...mentioning

confidence: 99%

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Selective Synthesis of Deuterated cis- and trans-Isohumulones and trans-Isohumulinones

Hamper,

Campbell,

Luo

et al. 2024

Synthesis

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Deuterated isohumulones can be prepared directly from humulones by an acyloin ring contraction under either magnesium catalyzed basic conditions or photochemical induced reaction in deuterated solvents. Reaction of humulones with biphasic methylene chloride/aqueous NaOD and MgSO4 in D2O gave stereoselective formation of cis-3d- isohumulones (cis-trans ratio of 82:18) as the magnesium salts in 71-83% yield. Greater than 95% incorporation of three deuterons was observed in the C5 position of the pentenone ring and the methylene position of the C4 acyl group. Photochemical isomerization with a 400 nm blue LED source provided stereospecific formation of deuterated trans-isohumulones in 36-82% yield with greater than 95% incorporation of deuterium in the C5 ring position. Oxidation of humulones with cumene hydroperoxide in basic D2O gave isohumulinones with partial 55-73% incorporation of deuterium due to keto-enol isomerization of the methylene substituent of the C4 acyl group. Structural identity of the deuterated products was determined by a combination of negative mode electrospray mass spectrometry (MS-ESI-) and 2D heteronuclear proton-carbon HMQC nmr analysis.

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“…:m/z(%) 361 (M-1, 100), 362 (22), 363 (3), 195 (50). HRMS (ESI-): m/z calcd for C21H29O5 (M-1) -1 : 361.2020; found: 361.2016 (-1.7 ppm).…”

Section: Ms (Esi-)mentioning

confidence: 99%

Section: Table 1 Reaction Conditions For the Isomerizat...mentioning

confidence: 99%

Selective Synthesis of Deuterated cis- and trans-Isohumulones and trans-Isohumulinones

Hamper,

Campbell,

Luo

et al. 2024

Synthesis

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“…The a-acids and iso-a-acids were analysed by the paper strip method4 or by a countercurrent distribution procedure. 5 (1) The influence of reaction time and a-acids concentration is illustrated in Table I.…”

Section: Reaction Conditionsmentioning

confidence: 99%

“…The yield of this reaction is 50% or even lower and in previous publications we have shown that this is in part due to oxidation. [1][2][3][4][5][6][7] The oxidation products we obtained in wort boiling conditions all have a five membered ring system, like the isohumulones, and they can thus be considered as oxidized derivatives of isohumulones.…”

Section: Introductionmentioning

confidence: 99%

Oxidation Products of Isohumulones

Vanhoey¹,

Vandewalle²,

Verzele³

1970

Journal of the Institute of Brewing

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A complex mixture of oxidation products is formed from iso-a-acids during wort boiling. These substances are already present in hops and persist to beer. Seven major constituents of such a mixture, obtained from pure humulone, were isolated by countercurrent distribution and their structures were elucidated, mainly by mass spectroscopy. The bitterness of the new beer substances was evaluated against trans isohumulone as a reference standard. These oxidation products of iso-a-acids are not extracted with iso-octane and they therefore escape the usual beer bitterness assay.

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“…(a) Extracts made entirely from organic solvents and free from tannins should be analysed by dissolving in methanol* and titrating with lead acetate using a conductance meter to detect the end-point. 24 (b) Extracts which contain watersoluble material should be dis solved according to the modified Wollmer technique19-28 as recom mended by the German Com mission for Brewing Analysis, prior to conductometric titration.…”

Section: Hop Extractsmentioning

confidence: 99%

European Brewery Convention: Analysis Committee Sub-Committee on Analysis of Hops and Extracts Methods of Analysis of Hop Extracts

1970

Journal of the Institute of Brewing

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For the conductometric analysis of hop extracts the method described by Bishop,6 is satisfactory provided the extract is composed entirely of resins; extracts which contain additional water‐soluble material should be analysed by an abbreviated Wöllmer technique. For isomerized extracts a qualitative examination should first be made, either by paper‐strip chromatography or by thin‐layer chromatography. A rapid counter‐current distribution procedure is suitable for the analysis of isomerized extracts: the modified Rigby & Bethune method22 is appropriate only with extracts which are known to be free from α and β acids.

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Analysis of Hop Extracts by Simplified Counter-Current Distribution Methods

Abstract: Simplified counter‐current distribution procedures are described which allow correct analysis of the α acids and iso α acids content of hop extracts.

Cited by 27 publications

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Selective Synthesis of Deuterated cis- and trans-Isohumulones and trans-Isohumulinones

Selective Synthesis of Deuterated cis- and trans-Isohumulones and trans-Isohumulinones

Oxidation Products of Isohumulones

European Brewery Convention: Analysis Committee Sub-Committee on Analysis of Hops and Extracts Methods of Analysis of Hop Extracts

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