Extraction of Bitter Acids from Hops and Hop Products Using Pressurized Solvent Extraction (PSE)

Jiří Čulík^1,3, Marie Jurková¹, Tomáš Horák¹, Pavel Čejka¹, Vladimír Kellner¹, Josef Dvořák¹, Pavel Karásek² and Michal Roth²
¹ Research Institute of Brewing and Malting, PLC, Brewing Institute Prague, Lípová 15, CZ-120 44 Prague 2, Czech Republic.
² Institute of Analytical Chemistry, Academy of Sciences of the Czech Republic, Veveří 97, CZ-611 42 Brno, Czech Republic.
³ Corresponding author. Email: culik@beerresearch.cz.

J. Inst. Brew. 115(3), 220–225, 2009 | VIEW ARTICLE

ABSTRACT
The EBC method 7.7, currently used for determination of bitter acids in hop products, is a time-consuming and laborious extraction technique. In this paper, our aim was to propose a new extraction method based on Pressurized Solvent Extraction (PSE) sometimes also called Pressurized Fluid Extraction (PFE) or Accelerated Solvent Extraction (ASE). Compared to conventional extractions, PSE offers a number of important benefits. PSE on OnePSE^® automated extractor was used for extraction of α- and β-acids from hops and hop products and the parameters influencing extraction efficiency and the influence of the sample preparation method were studied. The quantitative determination of α- and β-acids in the extracts was accomplished by using an HPLC apparatus equipped with diode array detector. The experimental results were compared with those obtained by the standard EBC 7.7 method and the two methods were found to be fully compatible.

Key words:
analysis, bitter acids, hops, hop products, pressurized solvent extraction, PSE.