Faults in Beer and Keeping it Fresh

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Faults in Beer and Keeping it Fresh

Faults in beer are basically any quality found in the beer that was not intended by the brewer. Flaws in beer can be introduced in both the brewing and the storage process. Some of the faults that can originate in the brewery are bacterial spoilage, ingredient variation, haze and improper carbonation level.

We are more concerned with averting faults that can be caused by improper storage of beer.

From the Oxford Companion to Beer by Garrett Oliver:

The three biggest causes of faults in packaged beer are light, heat and oxygen.

Once beer has been produced and is ready for sale, it needs to be stored. Normal bottling and kegging operations are performed at cold temperatures, and the brewery will keep beer in cold storage at approximately 38 degrees F. In the retail outlet, where possible, similar conditions should be maintained. However, most bottled beer will be destined for shelves at ambient temperature, and short periods here will do no harm. It is at this point that the beer becomes vulnerable to light, having often been removed from its case box. Light and heat are beer’s most potent enemies, the former causing skunky flavors and the latter speeding staling reactions. Strong light, especially direct sunlight, should be avoided, and any exposure time should be kept short. Direct sunlight can damage beer within seconds. Beer storage areas should be kept free of strong aromas because it is possible for some aroma compounds to transit the bottle closure and cause off-flavors.


Certain compounds in hops are light sensitive and when exposed to strong light a photo-oxidation reaction takes place, creating the intensely flavor-active compound 3-methyl-2-butene-1-thiol or MBT. MBT is one of the most powerful flavor substances known to man, and the pungent odor is commonly referred to as “skunky.”

Clear or green glass offers little to no protection against this reaction, but brown glass is highly effective, at least against short term or low intensity exposure. Aluminum cans or beer stored in kegs offers the best protection against exposure to light.


Heat and oxygen promote oxidized flavors, perhaps the leading fault in beer in the market. Oxidized characters are described as papery, cardboard and vegetal. Cold temperatures slow the oxidization process, while heat speeds the process. Again, short periods at ambient temperature, or going back and forth from cool to warm, without extremes, will do no harm. The longer beer is stored at cold temperatures the slower the oxidization process that occurs. Most breweries will put a “best buy” date on the packaging so that retailers can monitor the freshness of the beer. Typically, most beer will stay fresh for 90-150 days after release from the brewery. Beers such as IPA’s that rely on hops for much of the flavor will deteriorate more quickly than malt forward beers, and will take on a tea-like quality.


Packaging methods aim to keep oxygen levels below 80ppb in the finished product to maximize shelf life, but low levels only slow the aging process. Twist-off caps allow more oxygen to enter the beer than pry off caps. Wax seals also work well to prevent oxygen from getting into the beer. Cans are completely sealed from outside oxygen, but still have enough oxygen in them to allow oxidization over time.

We care about the quality of the products we sell, and strive to keep our beer rotated and FRESH!

Chip Bartsch

Beer Buyer