James Spencer (host of Basic Brewing Radio)  and I are happy to announce the fourth BYO/BBR Collaborative Brewing Experiment. This time around, we’re asking the question, “How much difference do wort clarifying fining agents such as Irish moss and whirlfloc really make?”

Irish moss and whirlfloc are two clarifying agents that brewers add to their kettles near the end of the boil. The idea is that these fining agents will stick to potential haze-causing molecules in the hot wort, drop out of solution and be left behind when the wort is racked from the kettle. But, how well do they really work? Is one better than the other? Do they also reduce the body or certain flavors or aromas in the finished beer? Do they work equally well with all beer styles (for example, pale beers vs. dark beers)? These are some questions we hope to answer in the fourth BYO/BBR Collaborative Brewing Experiment — and, as usual, we’re hoping that some of you join James and I in performing this experiment.

To answer all these questions, we’ve designed a straightforward experiment with a few different options. The basic experiment would be to brew two beers, identical in every way except that in one you add the recommended amount of Irish moss or whirlfloc and in the other, you do not add a fining agent. (If you don’t want 10 gallons of the same beer, consider brewing two half-sized batches.) As an option, you could brew three beers, one with Irish moss, one with whirlfloc and one with no fining agent added in the kettle. Or, you could brew two batches — Irish moss vs. whirlfloc.

We’re hoping to get a number of homebrewers, brewing a  variety of different styles, to brew two beers with us and then compare them, looking for differences in clarity and in flavor. Here’s the basic experimental protocol, with the data we’d like to collect:

 Experimental Protocol

Brew two batches of beer. Each beer should be brewed from the same recipe, with the same ingredients and on the same brewing equipment. Pitch the beers with same amount of yeast and ferment at the same temperature, preferably in identical fermenters. Every effort should be made to brew, ferment and condition the beers in an identical fashion — with one exception. The exception is the experimental variable — adding Irish moss, whirlfloc or omitting the clarifying agent.

For extract brewers, there is one slight twist — you need to account for the possibility of having different amounts of sediment (or trub) in your brewpot between batches. Different amounts of trub would lead you to collect different amounts of “thick” wort that you would then dilute in the fermenter. In order to account for this, brew the Irish moss beer first (which you would expect to have more sediment). When you rack the beer off the trub, note how much “thick” wort (or pre-dilution wort) you collect. When you brew the second batch, stop racking when you reach that amount. In other words, you may have to leave a small bit of wort behind, so your diluted worts are both of the same gravity. (If you’d like, save the wort left behind for use later in making a yeast starter.)

 Data to Collect

The basic information we are looking for is how the finished beers compare in terms of clarity, but there are a number of pieces of information that would be worthwhile. These include:

 1.) Observations of the finished wort and fermenting beer — If you can see the fermenting beer, do the two batches look different?

 2.) All the usual stuff — what kind of beer you made, OG and FG.

 3.) Comparisons of the final, conditioned beers, made by pouring each beer into an identical glass. Comparisons include:

 a.) comparison of clarity — How clear is each beer? If beers are very similar in clarity, try the “pencil test.” Hold a pencil behind the glass and see if you can read the writing on it. (If possible, take a picture of the beers, side-by-side, and send us.)

 b.) comparison of color — Does one beer appear to have more color than the other? 

 c.) comparison of head retention — Does one beer have more foam than the other (when poured in the same manner)? Does one beer have longer-lasting foam? Are there color differences in the foam?

 d.) comparison of aroma, flavor and body — Smell and taste the beers side by side. Do they taste identical, or are their differences? For example, does one smell more estery than the other? Is one more bitter or hoppy than the other? Does one have more body than the other? Note any differences.  

e.) anything else — As always, if you make an interesting observations, let us know. 

Keep watching James's website (www.basicbrewing.com) for a form to fill out when you've completed the experiment. (We're allowing six weeks for brewers to brew and condition their beers, so get started soon if you'd like to participate.) 

Also, keep watching my blog for the details of Experiment #5 — this one will be very easy. All you'll need to do is reserve some bottles from a single batch of beer.