Modulation of the Phytoestrogenicity of Beer by Monoterpene Alcohols Present in Various Hop Oil Fractions
Arne Heyerick, 1 Denis De Keukeleire, 1, 3 Carlos Van Peteghem, 2 and Sarah De Saeger 2
1 Ghent University, Faculty of Pharmaceutical Sciences, Laboratory of Pharmacognosy and Phytochemistry, Harelbekestraat 72, B-9000 Ghent, Belgium
2 Ghent University, Faculty of Pharmaceutical Sciences, Laboratory of Food Analysis, Harelbekestraat 72, B-9000 Ghent, Belgium
3 Corresponding author. E-mail: Denis.DeKeukeleire@rug.ac.be
J. Inst. Brew. 108(1):94-101, 2002 | VIEW ARTICLE
ABSTRACT
The estrogenicity of beer, due to prenylated flavonoids, mainly 8-prenylnaringenin, can be modulated under suitable conditions, whereby monoterpene alcohols present in hop oils act as precursors for prenylation of flavonoids. Four hop oil fractions, 'citrussy', 'estery', 'floral', and 'spicy', respectively, were investigated as potential sources. The main constituents were separated and identified by gas chromatography - mass spectroscopy (GC-MS). They were related to 8-prenylnaringenin via their MS features, while the ability to deliver a prenyl residue was evaluated by selected ion monitoring of fragment ions m/z 69 and m/z 41. In particular, the citrussy hop oil fraction proved to be a rich source of precursors for prenyl residues and linalool, the main constituent in the citrussy and spicy hop oil fractions, was shown to be most prominent. The process was highlighted by an increase in the content of 8-prenylnaringenin on forced ageing of acidified beer spiked with naringenin and linalool.
Key words:
Beer, GC-MS analysis, hop oil, monoterpene alcohols, phytoestrogenicity.
Publication no. G-2002-0321-04R ©2002 The Institute & Guild of Brewing