Whether you get your beer from our brewery, grocery store or your favorite bar, we do our very best to ensure you are buying (and drinking) the freshest beer possible.

Like many things, beer is delicate and its environment can have a positive or negative impact on its shelf life and quality of taste.

We sat down with a few members of our Quality Control lab team to talk through a few reasons why beer can taste off, and how you can perform an experiment from home to taste the off-flavors yourself.

Here are two cool experiments that you can do at home to help you learn and troubleshoot bad beer.

Materials:

-1 six-pack of Union Jack IPA bottles (the fresher the better – check the bottling date on the bottom-left corner of the bottle label). You can also use our twelve-bottle mix-pack of hoppy beers including Union Jack, Easy Jack, Luponic Distortion and Mosiac.

-1 sunny day

-1 hot car or warm-storage area, preferably consistently above 75 degrees Fahrenheit

Experiment 1: Lightstruck

Preparation:

-Take two bottles of Union Jack. Put one in your fridge (Beer 1). Place another in direct sunlight for at least three hours (Beer 2). Alternatively, you can shine a fluorescent light directly on it for three hours. After your three hours is up, refrigerate Beer 2 before assessment.

What to look for:

-A lightstruck beer will have a distinctly ‘skunk-like’ aroma. Outside North America (where there are no skunks) it may also be associated with fresh coffee.

Assessment:

-Pour your beers into two different glasses, leaving enough headspace to swirl. DO NOT SMELL THEM YET!

-Start out with Beer 1. Swirl and raise it slowly to your nose while performing short, doglike sniffs. Once you smell something (anything at all) take the beer away.

-Perform the same assessment with Beer 2. You will be able to perceive the ‘lightstruck’ aroma using these doglike sniffs.

What is going on?

-A beer becomes ‘lightstruck’ when certain hop acids are energized by UV light, leading to a breakaway of a specific sulfur compound: 3-methyl-2-butane-1-thiol. Clear and green glass provides no light protection to beers, and so beers stored in these bottles are very susceptible to the lightstruck character, though there are specialized hop products that can prevent this from happening if a brewer desires to package in such containers. Brown glass provides relatively good protection, but even prolonged exposure to light will lead to lightstruck flavors. Kegs, cans, and aluminum bottles are the only 100% lightproof packaging materials.

Fun Fact:

-Humans are exceptionally sensitive to the lightstruck compound, detecting it in concentrations as low as 4 parts per trillion (1 drop in 5 Olympic-sized swimming pools). But we desensitize to it easily as well (which is why you should assess it in short sniffs). If you do smell lightstruck while drinking in a beer garden on a sunny day, just take a big whiff of your beer and you won’t be able to smell lightstruck for five minutes or so. Enough time to enjoy a few skunk-free sips! Repeat until your beer glass is empty.

Experiment 2: Oxidation

Preparation:

-Take two bottles of Union Jack. Put one in your fridge (Beer 1). Place another (Beer 2) in a car trunk or warm storage room (>75 degrees). Wait at least 1 month, then refrigerate Beer 2 before assessment.

What to look for:

– Improperly treated beer will often have lower levels of bright, fresh aromatics and begin to exude characters of sherry, honey, paper, black tea, and other degradation flavors colloquially called ‘oxidation flavors’. Perceived bitterness often decreases as well, and the color and clarity of the beer may change too (getting hazier and darker if it was originally clear and light).

Assessment:

-Pour your beers into two different glasses, leaving enough headspace to swirl. DO NOT SMELL THEM YET!

-Start out with Beer 1. Take a look at the beer. Note its color and clarity. Swirl the glass and take a 1-second sniff. Take a 2-second sniff. Taste the beer. Swish the beer in your mouth, swallow, and exhale through your nose. Try to note the fresh grapefruit and pine aromatics. Try to rate the bitterness level on a scale of 0-10.

-Perform the same assessment with Beer 2. Does it look the same? Are the citrus characters as vibrant? Is the bitterness intensity and quality the same? Are you picking up any leathery, vegetal, honey, or sherry characters?

What is going on?

-Beer ages just like any food product. While pathogens cannot grow in beer (so it will not poison you if it gets old), treating a beer to warm temperatures, extended aging, or high and regular temperature fluctuation will accelerate a variety of chemical reactions that effectively suck the fresh flavors out of a beer, replacing them with flavor compounds we tend to associate with raisins, honey, cardboard, or decaying plant matter. IPAs, in particular, are chock-full of pleasant, but very volatile citrus and tropical fruit aromatics that degrade very quickly, and even faster if there are high amounts of oxygen in the package or the beer is subjected to temperatures higher than about 45 degrees Fahrenheit.

Fun Fact:

While 99% of beers are best when drunk fresh, a small amount benefit from aging. Firestone Walker releases a number of barrel-aged beers that achieve elevated complexity and richness both from the time they are allowed to mellow and from the barrels that they rest in. While there is some oxygen ingress through the barrels, we do our best to keep oxygen pickup to a minimum even in these beers.

Hope you have fun performing these experiments at home. Stay tuned for more experiments you can do from home. Cheers!