If you haven’t already seen it, please check out part 1 of this series, where I go through a little background on this study, along with discussing the changes in bitter and sweet flavors it found.

Probably the most puzzling taste BigD noted was the rise and subsequent quick fall of what he called the “Ribes” flavor. The term ribes generally refers to various plants belonging to the currant family. In the context of this study, BigD was speaking about the flavor associated with the leaves of black currant berries. I’m not sure if this is to be regarded as a positive or negative flavor development, as I have never really heard anyone else noting on this particular flavor being developed in their beer. I suspect it may be something specific to certain lagers, and generally not present in the beers we typically cellar.

A very important observation of BigD’s was the gradual development of a cardboard flavor in the beer. This taste, while not initially present, gradually becomes more pronounced as the beer ages. At one point after this study, this cardboard-like flavor was considered to be the preeminent staling taste for all beers. That point of view is no longer commonly held, as it has been shown cardboard flavors do not develop in all aging brews. The compound that mainly causes this flavor is classified as an aldehyde, and is called (E)-2-nonenal.

(E)-2-nonenal has been shown to be particularly prevalent in lager beers, and is a major reason why lager beers don’t generally cellar very well. The emergence of this compound also seems to be closely tied with the storage temperature of the beer, with higher temperatures resulting in a more pronounced cardboard taste. A very interesting thing is that this molecule is not actually formed in the aging beer. It is created during the brewing process and initially bound to other molecules. As these larger molecules degrade over time, the (E)-2-nonenal is freed up and we can begin to taste it.

Check back to part 3 of this series, where I’ll talk more about how this study fits in to the current research picture, and where subsequent studies have taken some of Big D’s ideas.

Jason

jason@brewbasement.com