Floating vs Headspace SPME for Beer Volatile Analysis

Abstract

Ever since Meilgaard’s classic papers attempting to unite the art and science of brewing, researchers have developed and employed a wide variety of chromatographic methods to identify and quantitate volatile organic compounds (VOC) that are major determinants of the flavor of beer. Many of these compounds can be found in the headspace and can be sampled directly or by adsorption and concentration on solid phase microextraction (SPME) media which can be bonded to fibers, stir bars or monolithic discs. In this report we characterize the sampling of VOCs by either floating or headspace analysis using monolithic discs with ODS and activated carbon coating. Using principle component analysis (PCA) we found that either method can be used to distinguish exemplars of five distinct beer styles. However, each method samples different sets of VOC s quantitatively and qualitatively. The floating method is simpler and more reproducible than the strictly headspace sampling and is better at sampling some high boiling point metabolites associated with flavor sensory character.