Naturally Cooling Your Wort

When it comes to brewing, besides perfect sanitisation the other deciding factor is temperature. If your equipment is sanitised correctly, from the pot you boil in to the spoon you stir the mixture with the only thing you have to contend with is the temperature of your wort (especially during the initial fermentation stage).

Depending on the style of beer you are making, your temperature will vary. One of the biggest problems I have as a homebrewer is cooling down the hot wort mixture before pitching my yeast.

Sure, I could put 20 litres of water into the fridge and let it cool overnight. But if you are like me, you’re a hobby brewer and if you don’t have a dedicated spare fridge lying about for brewing, you have just a standard fridge in your kitchen most likely with shelves and filled with food, condiments and drinks.

If you live somewhere cold and brew in the winter, you probably have the opposite problem where your tap water is cold. But because I live in a tropical climate (Queensland, Australia) even our winters can be laughably warm.

I don’t have the luxury of space in my fridge for cooling large amounts of water. I also don’t have the money or setup for an immersion chiller or any other cooler type setup to cool down my wort quickly. In Australia we also are susceptible to drought, so being smart with water is always wise.

I could also fill up my bathtub with ice, but the thought of going out and buying potentially 10 or so bags of ice seems like an unnecessary expense (probably around $30-$40).

So that leaves natural open-air cooling also commonly known as no chill brewing. Except, I wouldn’t dare open air ferment myself personally.

There is a lot of misinformation out there on no chill brewing. Some people are completely against the idea of letting your wort to sit before pitching the yeast and some see no issue with it as long as your sanitisation is good. So which is it?

We only have to look back to the old days of brewing (the early nineteen hundreds and even earlier), sanitisation was more relaxed and all fermentation took place in a vessel called a coolship (authentically known as a koelschip). A coolship is a large, open-top vessel where your wort cools. The size of it is generally large to allow for faster cooling.

One such brewery that uses an open-top fermentation approach like this is Anchor Brewing Company in San Francisco. While Anchor use fermentation tanks, the principle remains the same. They don’t cover their fermenting brews and if you have ever tried one of their beers, you’ll definitely taste the quality and no ill-effects of open-top fermentation.

While breweries like Anchor open-top ferment, they still cool their wort down first. They don’t let it overnight to naturally cool. So play it smart and cover your wort as it cools. If you drop yeast into infected wort, it will just turn out nasty.

The last two homebrews that I did I let my wort sit overnight and because my sanitisation was exceptional I had no issues. It also allowed me to get a nice yeast starter happening as well in advance, I always put a little extra yeast in just to be safe.

When no chill cooling your wort, always make sure you put it into your fermenting vessel and put the lid on to prevent contaminants getting in.

I personally put the wort right into the fermenting vessel, put the lid on and let it sit for at least 24 hours to cool down before putting the yeast in. Because my vessel is sanitised, I am not concerned about infection.

After you pour the wort into your fermenting vessel quickly put the lid on and then roll it on its side and make sure the wort touches all parts inside to sanitise it. That’s it.

If you are worried about contamination, take a small sample of the wort and put it into a jar and cover it with aluminum foil. Sit it near where your fermenting vessel will live and keep an eye of it.

Worthy of note is that using the no chill method will add in a variable to your brewing called hop utilisation. Essentially it means your hop additions will go for longer when you add them late into the boil.

When using no chill I usually throw my 20 minute hop additions in at the end of the boil or with two minutes to spare knowing they’ll continue to impart bitterness as the wort remains hotter for longer.

If your brew is going to become infected, your sample will show signs of growth. Never throw away a brew just because the wort cooled naturally and you’ve read that it means your beer will fail.