13,703
edits
Changes
first pass at sensory changes
==Chemical Changes==
===Sensory Changes===
[[File:Dalgliesh_beer_aging_sensory.JPG|thumb|Generalized sensory changes during beer aging according to Dalgliesh (not a rule of thumb) <ref>Dalgliesh, C. E. (1977). Flavour stability. Proceedings of the European Brewery Convention Congress, 623–659.</ref>]]
Beer aging is a complicated subject, and every beer ages differently. In general, sensory changes include a slow and gradual and steady decline in bitterness, partly due to an increase in a honey/toffee-like sweetness in the aroma and taste. Another flavor described as 'ribes', which is a sort of black currant taste, rises quickly sometime after packaging, and then gradually declines over time. After the 'ribes' flavor, a cardboard flavor slowly develops. Other findings claim that the cardboard flavor increases to a maximum, and then begins to decline after some time. Other changes include a rise in harsh, astringent notes in some beers, while wine and whiskey notes develop in very old beers. Positive flavors such as fruity esters and hop character fade considerably. These changes are not always seen as negative changes; studies have been done that show that drinkers sometimes prefer aged beers over young ones (even in light lagers). While the cardboard flavor has historically been emphasized in beer staling, it is just one component of beer aging. Many other flavor changes can occur, depending on the beer. For example, stronger beers have been found to develop burn, caramel, alcohol, licorice, and Sherry characters and no cardboard flavors. The development of many of these flavors corresponds with the amount of dissolved oxygen in the packaged beer and storage temperature <ref name="Vanderhaegen_2006">[http://www.sciencedirect.com/science/article/pii/S0308814605000865 The chemistry of beer aging – a critical review. Bart Vanderhaegen, Hedwig Neven, Hubert Verachtert, Guy Derdelinckx. 2006. DOI:https://doi.org/10.1016/j.foodchem.2005.01.006.]</ref>.
===General Effects of Oxygen===
(This is probably the most important thing to talk about first.)
===General Effects of Temperature===
The temperature at which beer is stored has also has a major impact on how beer ages. The effect that temperature has on a given reaction depends on the type of reaction; not all reactions are increased at the same rate. For example, it has been reported that beer stored at 25°C tends to develop more caramel flavor, while the same beer stored at 30°C develops more cardboard flavor <ref name="Vanderhaegen_2006" />.
===Haze===