Brew Day Part 5 – Wort Chilling and Pitching The Yeast
You’re done with the boil, so all the hard work is done, right? Not quite. The final step of making beer is to pitch the yeast and before you pitch the yeast, you need the wort to be chilled to the proper temperature. If the wort is too hot, you will just kill all the yeast. If the wort is too cold, the yeast will ferment very slowly. Most yeasts will require you to chill the wort down to 65-80 degrees before pitching. So how do you cool 1o gallons of liquid from boiling to 75 degrees? Let me show you some methods:
Chilling the wort is important not only because you want your yeast to stay healthy but the time between the end of the boil and the pitching of the yeast is a time when your beer is at extreme risk for infection. After you’re done boiling, you’re wort is a giant bucket full of sugar water which will attract all the wrong guests that can ruin your beer. Prior to and during the boil, you’ve got a security blanket because boiling will sanitize the wort. After your yeast starts to ferment, it creates alcohol which will also protect the beer from infection. But that sweet spot between boiling and fermentation is where your beer can run into trouble. That’s why it’s important to chill your wort as quickly as possible.
There are several methods of wort chilling that home brewers use. The methods may change based on the type of batches you are brewing and the equipment that you are using. They all use the same principal in different ways – use cold water and ice to lower the temperature of the wort. I’ll go over some common methods from basic to complex.
Topping Off The Batch
Topping off the batch is common with extract batches and really any beginner kits. The wort that you brew is going to be a smaller volume than what your final batch is and it’s going to be much more highly concentrated with sugars. Then you use ‘top off water’ to bring the batch to the full volume. This waters down the batch to the full volume and correct concentration of sugars (and eventually alcohol).
The huge advantage of this is that you can cool your wort very quickly by cooling or freezing top off water ahead of time. The disadvantage is that it’s probably not going to make a good quality of beer. The top off water can be a significant portion of batch…I significant portion that wasn’t exposed directly to the grains, hops or really anything. There’s also the risk of infection since your top off water wasn’t boiled. Hopefully you use a source of water that’s purified. Again this is something that is only recommended for beginning brewers.
The next step up in chilling is the ice bath. It’s very simple, you place either your boil kettle or fermenter into a bath of cold water and ice. This method is effective but it is very slow. It can take hours to get that temperature to drop. This is a method that could be used by any level of homebrewer but obviously as the batches get bigger, it takes longer to chill using this method and it increases your risk of infection.
You’d think that popping your fermenter into your fridge or freezer might be a quick way lower the temperature but it’s not very effective. It’s probably pretty close to the same time frame as the ice bath, there’s just too much of a temperature drop needed. The added risk is that your fridge and freezer could be crawling with bacteria due to the food, drinks and moisture in them.
Counter Flow Wort Chiller
A counter flow wort chiller might be one of the most important pick-ups you can make as a homebrewer. It’s a series of tubing wrapped in coils with the beginning of the coil attached to tubing with a hose attachment and the other end draining the water.
The coil is placed into the boil kettle during the last 10-15 minutes of the boil to sanitize it. Once the boil is finished, you attach the hose and start running water though. This cooler water never comes in contact with the wort but it has a cooling effect on the coils that causes the wort temp to drop.
This method is very efficient and used by even the most advanced homebrewers. One potential issue, especially in Arizona in summer, is the temperature of the ground water coming out of the tap. If the tap water is 90 degrees, you’ll never get your wort below that temperature. The solution some use is to make an ice bath and pond pump to pump ice water into the inlet instead of the hose water. Others use a second chiller and a pump. The first chiller gets water from tap that is chilled though an ice bath before being pumped to the second chiller in the brew kettle.
The plate chiller is the Cadillac of wort chilling. It can work very quickly and very effectively but it requires extra equipment and is more expensive then the other options.
The plate chiller has 4 inputs/outputs. The hot wort is pumped into one input and out another. On the other side cold water is pumped into it. The chilling effect happens in the plates. Both the hot and the cold liquids are pumped into the plates and cool/warm each other while never touching. It is similar to the counter flow chiller but it just goes about it differently.
For the extra equipment, you will definitely need at least one pump to pump the wort through. On the cold side, you can use a hose to attach on, however, if your tap water isn’t cold enough, it will not be effective. You can also use a second pump to pump cold water from another source. This is the method that I use. I use the HLT and fill it with ice and some water. That ice water is pumped through giving a quick chilling effect. As you can see in the picture above, I have added a digital thermometer to the outlet of the hot (wort) side. This tells me the temperature of the wort after leaving the plate chiller. When that temperature reaches the right pitching temperatures, that’s when you need to start transferring it to the fermenters.
In addition to this being a quick chilling method, you can more flavor and aroma out of your late addition hops by whirlpool. A whirlpool is created in the brew kettle when the wort is pumped back into the brew kettle after going through the plate chiller. On the return valve, you want to put a whirlpool arm, which is a bent tube that directs the flow of the returning wort to the side of the kettle. This causes a whirlpool effect and with the hops still in the boil kettle, more flavor and aroma can be extracted. All these things will help turn your homebrew from ok to good to great!
Pitching the Yeast
Once you’ve cooled the yeast down to the pitching temperature, you can pitch the yeast. Pitching the yeast is probably the simplest part of the day. All you need to do is take the yeast and sprinkle it into the fermenter. Yeast also needs oxygen to help start the process of fermentation. There’s many ways to do this but the simplest is just give a good shake and swirl. Many advanced homebrewers will add oxygen, but that’s not a step I’ve taken yet.
In my next posts, I will talk about the post brew day process, starting with fermentation and temperature control.