Recent Advances and Challenges for Beer Volatile Characterization Based on Gas Chromatographic Techniques

Beer is one of the most popular alcoholic beverages worldwide, taste and flavor being the main factors which contribute for consumers’ acceptance, and its volatile components represent the major contributors for beer global and peculiar aroma properties. Also, beer volatile components may be used to monitor the impact of raw materials composition, yeast metabolism, beer aging, beer distinction and screening of off-flavors, among others. The analysis of beer volatile fraction is very challenging due to the presence of CO2, and also a diversity of chemical structures, namely with different polarities, volatilities, and a wide concentration range. Thus, beer volatile analysis requires an effective extraction technique to recover representative information, minimizing modifications or/and loss of components. The different extraction and gas chromatographic techniques that have been used for beer volatile composition will be critically presented, exploring their advantages and drawbacks; wherein solid phase microextraction combined with gas chromatography is the methodology most frequently used, and a special attention will be given to these techniques. Furthermore, over the last decades, significant improvements have occurred on the chromatographs (namely the multidimensional ones), detection systems, columns technology and algorithms that contribute to the reduction of analysis time, making the methods more expeditious and user-friendly. Taking into account the information available in the literature, a comprehensive outline about the volatile components previously determined in beers is included, considering, when existing, data about their detection and quantification limits. This review presents the state-ofthe- art for researches who want to study beer volatile characterization.

Keywords: Beer, Beer volatile characterization, Chromatographic techniques, Comprehensive two-dimensional gas chromatography, Decarbonation, Extraction techniques, One-dimensional gas chromatography, Solid phase microextraction, Volatile composition.