Abstract 042
An Investigation into Hop Fractions Leading to Hoppy Aroma in Beer
Tech. Quart. Master Brew. Assoc. Am. 26: 62-69, 1989
K.J. Siebert, S.A. Ramus, T.L. Peppard, J.A. Guzinski,and L.J. Stegink
Aroma hops were fractionated in several ways. A series of pilot scale brews were made in which each of the aroma hop fractions was substituted for the last hopping in proportion to its abundance in the starting hops. Bitterness levels were adjusted with isomerized hop extract. The beers were tasted, and analyzed for hop volatile compounds by gas chromatography-mass spectrometry (GC/MS). While some compounds which do not readily steam distill contributed to the hoppy flavor of beer, nearly all of the hoppy flavor was associated with the oil fraction obtained by extensive steam distillation. Heating of solvent-extracted oil components before brewing did not enhance the hoppy flavor of the resulting beer. The nature of the flavor produced by a direct oil addition to the kettle, and the pattern of compounds observed, were different from a beer prepared with the leaf hops from which the oil was obtained. The differences appear to be due, at least in part, to greater losses in the kettle of some oil components added in isolated form, and to greater direct extraction from leaf hops in the case of at least one compound. Other compounds were found in comparable or higher levels with the oil addition. It appears, as a result, that it would be very difficult to match the flavor of a beer by substituting a hop oil addition for an aromatic leaf hop or hop pellet.
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