Many beer drinkers have found themselves in a situation where they left a six-pack or case of beer in a hot car for several hours. This leads to the obvious question: is it still safe to drink that beer once it has gotten so hot?
Quick Answer
The quick answer is that beer left in a hot car for more than an hour is probably best avoided if you’re concerned about safety. While a little bit of warming likely won’t make beer completely undrinkable, extreme heat can cause changes in flavor, aroma, and chemistry. There is a point at which the quality of the beer degrades so much that it may not be desirable or entirely safe to drink.
How Does Heat Affect Beer?
To understand why heat can make beer unappealing or potentially dangerous, it helps to know what happens to beer when it gets hot:
- Hop aroma and flavor compounds evaporate or degrade
- Malt flavors become concentrated and caramelized
- Esters that give fruity flavors are produced in greater concentrations
- Alcohol boils off faster than water
- Proteins and tannins coagulate, affecting mouthfeel and head retention
- Yeast cells rupture, releasing off-flavors
- Oxidation accelerates, leading to stale flavors
In general, hops are the most vulnerable to heat, while malts and yeast can also be affected. Oxidation happens faster at higher temperatures as well. Even a few hours above 90°F can rapidly change a beer’s aroma, flavor, color, and mouthfeel.
At What Temperature Do Problems Start?
It doesn’t take extremely hot temperatures to start altering beer. While beer is usually stored cold, between 35-55°F, problems can occur anytime the temperature rises above 70°F. Here’s a rough timeline of what happens as beer warms:
- 70-75°F – Freshness and hop aroma/flavor diminish
- 75-90°F – Fruit esters increase, proteins coagulate
- 90-100°F – Major changes in aroma, flavor, body, oxidation
- 100+°F – Beer is undrinkable, unsafe to consume
As little as 2-3 hours in a hot car around 90-100°F can cause significant degradation in beer quality and safety. At sustained temperatures above 100°F, beer can become completely undrinkable and potentially unsafe within 1 hour of exposure.
How Long Can Beer Sit Out Before Going Bad?
Assuming it’s been refrigerated, an unopened beer can typically last:
- Pale lager – 3-4 months past packaging date
- IPA – 2-3 months past date
- Stout/porter – 4-6 months past date
- Belgian styles – 4-10 months past date
- Strong ales – 12+ months past date if stored properly
However, once beer is removed from refrigeration, the clock starts ticking much faster:
- 24-48 hours at room temperature – Freshness declines, ideal to drink soon
- 1 week at room temperature – Noticeable oxidation and stale flavors
- 2 weeks at room temperature – Entirely undrinkable
- 1 hour above 90°F – Potentially undrinkable and unsafe
As you can see, beer can go stale quite quickly if left unrefrigerated. And elevated temperatures accelerate the staling process.
Does Alcohol Percentage Matter?
Generally, yes. Beers with higher alcohol content will hold up better to heat exposure. Here’s why:
- Higher alcohol beers have less water content, so there’s less moisture to evaporate.
- The alcohol itself helps stabilize and preserve the beer.
- More robust malt and yeast character stands up to oxidation.
- Fuller body and mouthfeel is retained better.
- Stronger hop bitterness and flavor withstands fading.
For these reasons, a high alcohol beer like an Imperial IPA or a barleywine can often survive heat better than a low alcohol beer like a light lager or blonde ale. But this isn’t an absolute rule – any beer can become unsafe if it gets hot enough for long enough.
Does Bottle vs Can Make a Difference?
Yes. Cans provide much better protection against heat damage and oxidation. Here’s why:
- Cans completely block light, avoiding “skunky” flavors.
- Cans have a complete seal, preventing oxygen exposure.
- Cans have less air space at the top for oxygen to affect the beer.
- The aluminum conducts heat away from the beer better than glass does.
For these reasons, a beer left in a hot car for several hours will probably fare better in a can than in a bottle. The can provides a protective barrier against light, oxygen, and some heat. However, enough heat will still ruin canned beer too.
Tips for Rescuing Hot Beer
If you do end up with a six-pack of hot beer, all is not lost. Here are some tips to rescue beer and make it more palatable:
- Get it cooled down ASAP – Refrigerate for several hours if possible.
- Keep it upright – This prevents oxidation and preserves carbonation.
- Open carefully – Pour gently into a glass without agitating.
- Use it in beer cocktails or recipes – The alterations in flavor may work well mixed and chilled.
- Cook with it – Use hot beer in stews, chili, or even dessert.
- Freeze it into beer slushies – The ice can help mask off-flavors.
With some creativity, you may be able to avoid pouring hot beer down the drain. But if it tastes rancid or smells spoiled, it’s better to be safe than sick.
Potential Safety Issues
At warm temperatures, beer is generally safe. But when beer gets extremely hot for too long, there are some potential safety issues to consider:
- Foodborne illness – Bacteria like Lactobacillus and Pediococcus can produce off-flavors, acids, and diacetyl that cause spoilage.
- Acetaldehyde – A carcinogenic compound produced by yeast at high temperatures or as a result of oxidation.
- Methanol – Toxic alcohol produced when pectins breakdown at high temperatures.
- Skunky thiols – Unpleasant mercaptans produced when isohumulones react to light.
- Propylene glycol – An additive banned in Europe that can turn into lactic acid and acetaldehyde.
Signs of potential safety issues include sour, buttery, or rotten smells, extreme skunkiness, and viscous, ropey texture. If beer seems abnormal in odor, appearance, or mouthfeel after heat exposure, err on the side of caution and discard it.
When is it Definitely Not Safe to Drink?
There are a few clear signs that beer has become undrinkable and unsafe after heat exposure:
- Curdled, chunky appearance
- Putrid odors – Rotten, skunky, rancid
- Mold visible on surface
- Gushing or overflowing when opened
- Sour, vinegar-like taste
Once beer takes on these negative attributes, it should not be consumed. The altered aroma, appearance, mouthfeel, and flavor indicate the beer has likely been contaminated or severely oxidized.
Preventing Hot Car Beer in the Future
To avoid ending up with a stash of undrinkable hot car beer again, follow these tips:
- Park in the shade when running errands
- Bring a cooler with ice packs in the car
- Cover beer with a reflective sunshade
- Wrap beer in towels to insulate it
- Take only what you’ll drink right away if unsure of time
- Keep beer up front near AC vents
- Never leave beer in a hot trunk
Taking simple precautions can prevent beer from getting too hot in a car. Try to keep beer shaded, insulated, and near cooling sources when transporting it on hot days.
Does Hot Beer Give You the “Runs”?
You may have heard a myth that drinking beer that got warm will lead to diarrhea or intestinal distress. Is there any truth to the claim that hot beer gives you the “runs”?
There are a few potential explanations for this belief:
- In the past, beer was less sanitary and more prone to pathogens that could cause illness if allowed to grow in warmth.
- Fermentation byproducts like butyric acid can have a laxative effect if consumed in large amounts.
- The ethanol itself can accelerate gastric emptying and loosen stools.
- People may drink more warm beer more quickly, causing temporary digestive upset.
Modern beer making standards ensure there are no significant amounts of laxative compounds or bacteria produced in beer at any temperature. While there are anecdotal reports of hot or skunky beer causing loose stools, there are no scientific studies confirming clear links. In most cases, the diarrhea may be coincidental or related to overconsumption of alcohol itself.
The Verdict on Hot Car Beer
So can you drink beer left in a hot car? Here is a summary:
- Below 70°F – Beer is safe but best consumed soon for peak freshness.
- 70-90°F – Quality decline but beer is likely still safe to drink in moderation.
- 90-100°F+ – Rapid deterioration of aroma, flavor, mouthfeel and safety risk increase.
- 100°F+ for 1+ hour – Beer is unsafe to drink and should be discarded.
While beer can withstand some warmth, extreme heat quickly takes its toll. Whenever possible, keep beer properly chilled. And if the beer seems off in any way after warming, err on the side of caution – grab a fresh cold one instead.
Conclusion
Drinking a beer that has been left in a hot car for several hours is generally not recommended. Even short amounts of time above 90°F can cause the beer to become skunky, stale, or potentially harbor harmful bacterial contamination. While the beer may still be safe if kept below 70°F, the quality and taste will go downhill the warmer it gets. Your best bet is to keep beer properly refrigerated or in coolers when transporting and replace any unrefrigerated beer that has been left out more than 1 hour. In cases where the beer becomes extremely hot for a prolonged period, it has likely deteriorated in safety and flavor so much that it is best discarded. With proper care, you can avoid drinking bad beer and only enjoy properly chilled brews for maximum refreshment and taste.
