The influence of pruning and harvest timing on hop aroma, cone appearance, and yield.

Humulus lupulus (hop) cone is a key ingredient of beer, which determines its taste and aroma. Thus, it is necessary to control its cultivation conditions to acquire suitable quality. Here, cultivation conditions, such as pruning, blooming, and harvest timings, were modified for the Saaz hop variety in the Saaz region of Czech Republic.

Different beers with different hops. Relevant compounds for their aroma characteristics.

Hop-derived aroma characteristics in beer are very important for the quality of beer. This study compared the differences of hop aroma characteristics and the compounds contained in beer by changing the variety of hops applying the idea of "food metabolomics" on the GC×GC/TOF-MS analysis data, to clarify which aroma compounds contribute to the differences of hop aroma profiles indicated by sensory descriptors. As a result, by focusing only on hop-derived compounds, 67 compounds were strongly correlated with one or more of the sensory descriptors.

Decrease in hydrogen sulfide content during the final stage of beer fermentation due to involvement of yeast and not carbon dioxide gas purging.

We observed a rapid decrease in hydrogen sulfide content in the final stage of beer fermentation that was attributed to yeast and not to the purging of carbon dioxide (CO(2)) gas. The well known immature off-flavor in beer due to hydrogen sulfide (H(2)S) behavior during beer fermentation was closely investigated. The H(2)S decrease occurred during the final stage of fermentation when the CO(2)-evolution rate was extremely small and there was a decrease in the availability of fermentable sugars, suggesting that the exhaustion of fermentable sugars triggered the decrease in H(2)S.