How temperature plays a role in homebrewing

best - measuring the temperature of beer with a thermometer

Why do I need to take the temperature when brewing beer?

If you know the story of Goldilicks and the Three Beers, you'll know that she eats the bear's porridge and she fines it:

Too hot

Too cold

And just right!

Which is how the temperature of beer works in determining that beer tastes just right. A beer that is brewed at too high a temperature may produce unwanted fruity flavours (esters) or excessive diacetyl traits.

A beer that's too cold won't even brew at all. And that's just no fun, even for Goldilocks.

So, if you know that the beer you are making needs a certain kind of temperature, how does a brewer work the temperature out?

The classic tool known as a thermometer.

Easy huh?!

But let's cut to the chase. The Etekcity Lasergrip Laser Infrared Thermoeter is the bees knees and well worth a trial.

Pitching Yeast at the correct temperature so you don't kill yeast

'Pitching yeast’ is just homebrewer lingo for adding your yeast to the wort.

Pitching your yeast is more than simply adding it to your beer – it needs to be done at the correct time in the brew so that it can activate properly and begin fermenting. If you pitch your yeast when your brew is too hot (say you’ve just boiled it), you will kill the yeast with the heat and fermentation will not occur.

Hence, brewers should use a thermometer to ensure the correct pitching temperature has been achieved.

The benefits of using a glass thermometer

glass thermometer for home brewing
Many home brewers will be quite familiar with the standard floating glass thermometer that seems to be supplied with some many beer kits (historically at least).

These glass thermometers generally are designed to measure a temperature range of 0-100 Centigrade (32-212 Farenheit). A great benefit of using them is that it is there use is so simple - it can be simply dropped in your pot or mash tun. It will of course float and be able to be read when ever you like.

Another benefit is that glass thermometers are an entirely enclosed system so you should have no issues with their operation and and are rarely inaccurate so you can rely on them

Being glass, they are of course susceptible to breakage more easier than some of the heavy duty temperature measuring devices.

Storing beer at the correct temperature

Generally speaking, it's good practice to store your beer in a warm place. This will encourage secondary fermentation (this is sometimes described as bottle conditioning).

The ideal temperature range is between approx 18 - 25°C for 5 to 7 days.

HOWEVER after that period, you should leave them in a much cooler place with a temperature range between approx 8 - 12°C. Three weeks a good length of time at that temperature range before you crack open a bottle.

Behold, the Bi-Metal Dial Thermometer (and how to use one!)

A step up from a floating unit, a bi-metal dial thermometer is a more robust measuring device which will give you a quick reading when checking the temp of the mash tun. They are some times called kettle thermometers.

These dial thermometers are also fairly easy to calibrate and they need to be as they can become inaccurate easily, especially when brewers use them frequently regularly. Dropping them once or twice certainly does not help so their calibration should be checked often.

The use of the bi-metal thermomter is pretty simple - the have a clip which fastens to the tun or kettle. The 9 inch probe they have extends into the wort to take the measurement. 

A good quality dial thermometer will be welded with a stainless steel housing and corrosion resistant to most chemicals. Like this Tel-Tru 42100909 Model from Amazon!

This is why the cooling process can be so important.

Cold Crash and temperature

When cold crashing beer you want the beer to be really cold so the yeast becomes flocculent and falls to the bottom of the beer.

You don't want to freeze your beer but you want it pretty cold so using a thermometer to measure the coldness of your fridge or unit you are doing the crashing in is pretty smart.

The common recommended range varies from 33 degrees Fahrenheit to 40 degrees F, with 38 degrees F being a fairly popular temperature point. 40 F is about 4.4. Centigrade.

Just remember a 5% ABV beer can start to freeze at 28F.

Now here's the big daddy of getting a read on temperature:

Using Infrared Digital Thermometers when brewing

An infrared thermometer is the bees knees in regards taking the temperature of your brew. You do not dip the unit in the beer wort you use project a laser at an object (such as beer) and the device then measures the temperature based on the infrared reflection.

So basically to use it you just point and shoot it at the surface of the water and it will give you the surface temperature reading. One reviewer on Amazon said "I found it to be quick and accurate for measuring water, the temperature of the pot itself, and external temperatures of fermenters."

So, let me introduce you to the:

infrared scanner to check brew temperatureEtekcity Lasergrip 1080 Non-contact Digital Laser Infrared Thermometer Temperature Gun

Pew ! Pew ! Pew!

  • It features a versatile design: Infrared Technology makes this thermometer handy to use when cooking and barbequing, performing auto maintenance, doing home repairs, and of course brewing beer. Measure all the from -58℉~1022℉/ -50℃~550℃
  • Better accuracy: the distance to spot ratio is 12: 1, meaning the Laser grip 1080 can accurately measure targets at greater distances compared to most other ir thermometers
  • Target quicker: a built in laser gives you the precision to hone in on the exact space you want to measure. 
  • Added function: the LCD screen is backlit, also has an auto-off function to extend the battery life, and features a low battery indicator so you never accidentally run out of juice (battery included, booya!)
We say the real benefit of using this device is that you don't need to get even close to hot water or wort - you can keep your distance.

I've seen it reported by brewers that when working with an all grain mash tun infrared devices can have some trouble. The foaming and grain on top of the mash tun can  interfered with the laser which can give incorrect readings.

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