Analysis of volatile compounds from a malting process using headspace solid-phase micro-extraction and GC-MS

The aroma of malt is one of the most crucial factors that influence the flavor of beer. To better understand the behavior of aroma during malting process, we identified the volatile compounds from barley, green malt and malt by using headspace solid phase microextraction (SPME) and gas-chromatography/mass spectrometry. A total of 47 volatiles, comprising aldehydes, ketones, alcohols, acids, and furans, were identified during the complete malting process. In particular, the dynamics of 2-methyl-propanal 3-methylbutanal, 2-methylbutanal, hexanal, 2-hexenal and 2-nonenal, commonly considered as key odorants in barley and malt, was highlighted during the process. Among these compounds, the amounts of 2-methyl-propanal, 3-methylbutanal, 2-methylbutanal, and 2-nonenal increased during the roasting stage, and the ones of hexanal, 2-hexenal conversely decreased in the same stage. As to compounds of ketones, alcohols, organic acids and furans, there is no forming regularity for them, which they formed at different stages of the whole malting process. Meanwhile benzaldehyde, benzeneacetaldehyde, 1-hexanol and ethyl acetate were considered as possible key odorants during the whole malting process. Base on the results above suitable manipulation of the malting conditions could be supplied in an industrial scale.

► SPME combined with GC/MS was a valid alternative method. ► Forty-seven volatile compounds from a malting process were identified in an industrial scale. ► The forming regularity of volatile compounds identified was determined. ► The dynamics of volatile compounds during the malting process was determined. ► The possible pathway for the formation of benzeneacetaldehyde in malting process was referred.