Hop compounds

Supercritical-fluid chromatography (SFC) has been demonstrated effective in the analysis of a-, / -, and iso-a-acids (54). However, few analytical laboratories have SFC installations, so its use as an analytical tool for the analysis of hop compounds is extremely limited. Interestingly, SFC and GC provide the opportunity to move away from the problems associated with differential response factors, because these methods rely on flame ionization detection. 

WJ Simpson. Ionization behaviour of hop compounds and hop derived compounds. J Inst Brew 99 317-326, 1993. 

WJ Simpson, ARW Smith. Factors affecting antibacterial activity of hop compounds and their derivatives. J Appl Bact 72 325-334, 1992. 

Humulone (7), from Humulus lupulus (Cannabaceae), is partly responsible for the bitter flavor in beer. About 35 ppm of hop-derived substances contibute a specific bitter taste and hoppy flavor to beer. Hops also contribute for the microbiological stability and the stability of foam of beer (De Keukeleire, 1991). However, the activity comes not from the native hop compounds, but from iso-a-acids produced by boiling the wort-containing hops (De Keukeleire et al., 1992 Bonded et al., 1987). 

The word flopside structure has been introduced to characterize a biaxial magnetic structure observed in the cubic HoP compound (Fischer et al. 1985). As shown in fig. 121 the propagation vector is and the structure is formed as... 

Foaming is an important criterion of the taste of beer. A distinction is made between foam volume (produced by the content of carbon dioxide), foam density, and especially foam stability (caused by protein degradation products, bitter hop compounds, and pentosans). Lower fatty acids that are present in beer bouquet act as de-foamers. 

The first attempts at structural determination of hop compounds are ascribed to Barth in 1900 (12). He concluded that humulone exhibited acidic properties in view of its ability to form salts. Schnell obtained two decomposition products by alkaline treatment valeric acid and an unsaturated oxyketo acid (13). The latter compound was described as a weak monocarboxylic acid carrying an enolic hydroxyl function (colouration with iron(lll) ions) and referred to as a pseudoacid. The empirical names, humulone and humulinic acid, for the alkaline degradation product, were coined by Schnell. 

For most of the five-membered ring hop compounds, such as the isohumulones. 

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