When you think about draft beer, you’re most likely thinking about the enjoyment of drinking it. What you’re less likely to be aware of is how the temperature of beer systems is absolutely critical for maintaining the perfection of your pint. Here’s an overview of how temperature affects the quality of your beer before it ever reaches your glass.
One of the best parts of beer is the carbonation—those perfect bubbles that fizz on your tongue and give beer part of its distinctive taste. Those bubbles—the natural result of fermentation—are comprised of carbon dioxide gas, which like all gases expands and contracts in relation to temperature. Because the bubbles in beer expand in warm temperatures and contract in cold temperatures, beer whose temperature hasn’t been controlled properly will have bubbles that behave oddly.
If the beer in the keg becomes too warm, the beer will foam, releasing the carbon dioxide in the bubbles which will then affect the taste and the appearance of the beer once it’s served. Because foam is about 25% beer, allowing beer to foam in the keg basically means that ¼ of the beer in the keg is going to waste—a tragedy for both your tastebuds and your pocketbook. If the beer in the keg is too cold, on the other hand, then the carbonation will remain inside the beer, not expanding until it reaches your stomach, giving you a stomachache.
To make sure that the beer is the right temperature so that the bubbles behave properly, you need to make sure that your keg goes through as few changes in temperature as possible. You might not be able to control the keg’s temperature while it’s being transported between the brewery and your front door, but you can control the refrigeration once it reaches you.
The ideal temperature for draft beer is 38°F, so you should make sure that your cooling unit is properly maintained and capable of remaining at a constant temperature. Since it takes more than twice as long for a keg to cool down from 48°F to 38°F as it does for that same keg to warm up the ten degrees from 38°F to 48°F, it’s in your best interest to make sure as much as possible that the keg never has any reason for its temperature to increase.
In addition to temperature changes inside the keg, you should pay attention to temperature changes in the rest of the system. The lines that carry the beer from its point of origin in the keg to the tap that dispenses the beer into your glass are prime places for beer to warm up and go bad.
To prevent this from happening, insulate your beer lines. Wrap the lines with aluminum foil followed by a layer of foam, and your beer should stay nice and cold. To make sure, have a thermometer inside of the beer cooler (or taped to the keg) and another one at the tap. If they both read 38°F, you’re doing things right.
If you pay attention to the temperature of your draft beer system, you’ll never again have to worry about your beer going flat or otherwise being inappropriately carbonated. Now that you know to keep your system at a cool and constant 38°F, all your pints should be perfect!
Diana Carlton is a writer for Micro Matic, the world’s leader in beverage dispensing equipment solutions. For restaurants, bars, and pubs across the nation, Micro Matic has supplied the highest quality equipment and expertise for their beverage dispensing systems. With decades of experience in draft beer systems, Micro Matic is also an innovator in the wine on tap industry.
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