First, I want to talk to you about optimum fermentation temperatures. When you get your yeast look on the package and see what the supplier says is the optimum temperatures. The package of White Labs Irish Ale Yeast I have here says the optimum fermentation temperatures varies by style:
For Ales the temperature range is 65 to 69 degrees. For Wheat-Belgian beers the temperature range is 68 to 78 degrees and for Lager beers the temperature range is 50 to 55 degrees. So, depending on the beer style you are brewing the optimum fermentation temperature is going to be different. Now say that:
It’s All About Fermentation Temps!
If you are a brewer chances are you had that time where the fermentation temperature got way to high, the beer went nuts, clogged the air lock and then blew the air lock off the fermenter. I now use a blow off tube and bottle.
Tasting a lot of other people’s homebrew at events and homebrew club meetings and looking back on my earlier days of homebrewing and the mistakes that I made most of the faults come down with an issue of fermentation temperatures. In most cases the temperatures gets way too high and produce all sorts off flavors.
So, if there is one thing you can do to improve your beer the most, it is to control your fermentation temperatures.
By controlling your fermentation temperature, you can avoid most off flavors, such as:
Excessive esters: Every beer has esters in it, certain beers more than esters than others. German wheat beers for example have a lot of grade bubble gum and banana esters. British beers have esters, but it is a fault if there is to many of them and when the temperature gets too high they get really fruity and kind of nasty tasting.
Same thing with excessive phenols that plastic, vinyl, iodine taste and smell. You do not want excessive phenols in your beer and when the fermentation temperature gets out of control that’s what happens.
Other off flavors you can solve by controlling your fermentation temperature:
Diacetyl: That is the buttery, butterscotch, movie theater popcorn like flavor in your beer.
Solvent-Like: Is that paint thinner, nail polish remover (acetone), harsh, sharp taste and smell.
Alcoholic: flavor is the overpowering alcohol flavor, bitter, acetone, paint thinner. Same thing with that alcoholic flavor.
Acetaldehyde: Which is that green apple, rotten-apple flavor.
So, really if you can get a handle on this technic you can wipe out a lot of off flavors. Most importantly this really can give you a cleaner tasting beer. Often when you taste a beer that you don’t really know exactly what’s wrong with it, usually it comes down to issues of fermentation.
This method works best for American Ales and English Ales. So, your IPAs, Pale Ales, Amber Ales, Brown Ales, Stouts, Porters, and ESB (Extra Special Bitter). These are really the beer styles that most homebrewers are making these days.
You can also use this method for other types of beers such as Lagers, Belgians, German beers but often these beers require a little more specialist fermentation temperature control.
Step 1. Pitch Low & Let Rise
What this means is adding the yeast at a little lower temperature than usual and let the temperature rise a couple of degrees. Let’s say that you normally chill your beer to 70 degrees and you do not have any temperature control and you just let it sit there. I am saying instead you chill it down to 66 degrees on the cooler side and then let it warm up a couple of degrees to the fermentation temperature of 68 degrees. What pitching low does, it gives you a good buffer if you do not have good temperature control. If you don’t have a chest freezer and thermostat and you are chilling to a warmer temperature saying low to mid 70s you are putting yourself in the danger zone, because the beer is going to heat up on its own anyways. You do not want to be in the mid to upper 70s, that is when those off flavors get produce. By pitching lower you are giving yourself a buffer zone. You’re also waking up the yeast a little bit by the free rise, so the yeast gets more active the warmer the temperature gets. So, that is step 1, pitch low and let the temperature rise over the course of a day or so.
Step 2. Hold the Temperature Steady
Hopefully you have some method of temperature control to be able to hold the temperature steady. Step 2 is holding at that temperature; 68 degrees is a good temperature for most beers. You want to hold that temperature through the bulk of fermentation. Say 90% of fermentation.
Step 3. Raise Temperature at the End of Fermentation
The first two steps are going to eliminate a lot of the off flavors. So those solvent-like flavors, the alcoholic, the excessive fruity and the phenols. These occur when you get up into the mid to high 70s and even 80s. But at the end of fermentation we want to clean up the beer from any off flavors by letting the temperature to rise just a couple of more degrees. This will clean up Diacetyl, the butter flavor. The reason we can let the temperature rise and not worry about producing a lot of off flavors is that most of the flavors that are made in your beer are made within the first 72 hours. Since we are outside this range we don’t have to worry so much with letting the temperature rise. At the end here, we are going to get the yeast more mobilized and they are going to come around and clean up your beer. This little rise at the end will clean up the diacetyl.
OK, that is the 3-step method for eliminating most off flavors in homebrew.
If your homebrews really haven’t been up to stuff and you haven’t put you finger on why and they haven’t been to clean tasting to polished tasting, then I recommend you give this method a shot and see if it will turn your beer around.
I got the this information from the Homebrew Academy website and a 3-Step Process to Eliminate Off-Flavors video is available on YouTube.