Their study identifies key substances involved in giving beer an aged or "oxidized" flavor.

In the new study, Adriana Bravo and colleagues point out that past efforts to keep beer fresh have focused on protecting beer from contact with the air throughout the brewing process. That focus, however, has resulted in only a relatively small improvement in flavor stability.

The research identified a group of poorly understood substances called alpha-carbonyls as important culprits in the decline in fresh flavor that occurs as beer ages. It also showed that levels of some of these substances could be reduced by adding ingredients that block their formation, thus making beer taste fresher longer.

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Journal Reference:

1. Adriana Bravo et al. Formation of alpha-Dicarbonyl Compounds in Beer during Storage of Pilsner. Journal of Agricultural and Food Chemistry, May 28, 2008 [abstract]