In this blog, I’m happy to announce a collaboration between Brew Your Own, Basic Brewing Radio (www.basicbrewing.com) and homebrewers who are interested in science. We haven’t thought of a cool name for it yet, but it’s a series of experiments designed to put some basic homebrewing wisdom to the test.

For each in the series, we’ll explain the experiment on Basic Brewing Radio and in this blog. Interested homebrewers can then perform the experiment and report their results to us. (We'll be doing the experiment, too.) We’ll compile everyone’s data and present the results in the magazine and on the podcast.

James Spencer (Basic Brewing Radio) and I will choose the experiment each time around, looking for experiments that are relatively easy to do and have the potential to yield a clean, unambiguous result. (We’ll favor experiments that rely on comparing objective data -- OG or FG readings, comparisons of color, etc. -- versus highly subjective types of tasting data.) If you have an idea, please contact us and we’ll consider it.

We realize that most homebrewers don’t have a science lab in their house. Neither will most want to participate in experiments that take tons of work or tie up all their equipment. So, we’ll try to make the experiments quick and doable. As such, sometimes there will be a compromise between the best possible experimental design and our experimental design.

In real science, scientists perform quickie, exploratory experiments all the time, often to determine whether conducting the full-blown experiment will be worth it. In cases where you expect one of the experimental variables to show a big effect, a quickie experiment will often give you a usable result. (We’ll also give you science-types an explanation of how to improve on our basic experiment.)

Experiment 1
Our first experiment was suggested by Brain Glenn from Cleveland, Ohio. He wanted to test whether leaving your batch sitting on the yeast in primary for an extended amount of time caused off flavors. Many sources claim that the yeast will autolyse and give your beer rubbery/sulfury off flavors. Other homebrewers dismiss this idea.

 Below I give three quick ways to test this experiment. The first is the easiest, and should yield good results if the extra time on the yeast has a pronounced effect on the beer. The second two versions of the experiment address shortcomings in the "quicky" experiment. If you feel like participating and are willing to put in a little more effort, please give one of these a try.

One Carboy Experiment
For the easiest version of the experiment, you only need to brew one batch of beer. The style and recipe are your choice. Let the beer ferment as you normally would. Once it has finished, rack half of the beer to your bottling bucket or keg. Return the air-lock to your carboy and let the remaining half sit for two weeks on the yeast. Then package the second half of your beer. (Be sure to label which bottles contain which beer.) After a couple weeks of conditioning, take the final gravity (FG) of each beer. Also, taste them side by side. Can you tell the difference? That’s the experiment. If letting beer sit on yeast does cause a change in the beer, this experiment should demonstrate this.

See the forms at www.basicbrewing.com/experiment for more detailed instructions and what data to report to us.

Two Carboy Experiment
Ideally, in an experiment, the only difference between different trails should be the experimental variable. In our case, this would be the contact time with the yeast. But, if you look at the design of the first experiment, this isn’t exactly the case. Half of the batch gets packaged before the other, giving it more time to condition. Additionally, the first half will experience some oxygen exposure that the second won’t. With a little extra effort, we can control for these variables. All you need is an extra carboy and a little extra time.

For the two-carboy version of the experiment, brew your beer as usual, but have a second sanitized carboy ready as the beer ferments. Once fermentation ceases, rack half the beer to the second carboy and let them both sit for two weeks. Then package them both at the same time. This takes an extra carboy and an extra little bit of work racking, but it evens out both the amount of time in the carboy versus bottle conditioning (or time spent in the keg) and gives both of the trials the same exposure to oxygen.

Three Carboy Experiment
When most homebrewers leave their beer in primary, they don’t open the carboy, as happens in the first two experiments when we rack out half the contents. If you have a third carboy on hand, and are willing to put in a bit more work, there is a third option.

In this option, make your wort and split it evenly between two carboys. Pitch the same amount of yeast to each and let them ferment out. When the fermentations cease, rack one of the carboys to secondary and leave the other on the yeast. This more closely mimics the differences the beer would experience in real-life situations.

 . . . and Beyond
No experiment is ever perfect. To refine ours even more, you could add multiple trials, to  control for the inevitable random differences between trails, closer tracking of potential differences between trails due to things like one carboy sitting closer to the evaporator coils in your fermentation chamber, etc. But, although these experiments may be better controlled, let’s face it -- nobody is going to do them.

So, if you’re interested in furthering homebrew science as you brew, take a look at the experiments outlined and above give one a try.

 I've got updates on my barley, hops and the beer I brewed with homegrown hops soon.