If you’re all-grain brewer, you’ve probably made a second beer sometime. You may have brewed a big beer then and realized that you had plenty of sugar left in the grain bed. After rinsing it out with hot sparge water, you made a second beer. Alternately, you may have read about what some homebrew source described as parti-gyle brewing — brewing a big beer from the first wort and a second beer from the sparged wort — and given that a try. If you did, you were probably disappointed. I know I was. The first few times I tried this, the second beer was grainy and lacking in malt aroma. Overall, it had an iced-tea-like character. Not to put too fine a point on it, but the beer wasn’t any good.
As it turns out, there’s a reason why a beer made entirely from wort collected late in the runoff will not be of good quality. However, there is a way to brew a decent second beer (and actually practice parti-gyle brewing in a manner that more closely matches how commercial brewers did it). In order to understand why a second beer made only from sparged wort is bound for failure, let’s examine what happens when you mash and run off the wort.
The Changing Character of Collected Wort
At the end of your mash, you have a vessel full of grain husks sitting in the surrounding wort. When you start running off the wort, before any sparge water has been added, it is called first wort. First wort has the following characteristics. It is relatively high in specific gravity. The exact specific gravity depends on your mash thickness and extract efficiency, but values in the ballpark of 21 °Plato (around SG 1.087) are common in homebrewing. Not only is the first wort high in sugar, it is relatively high in soluble protein (compared to the later, sparged wort). The pH of first wort is the same as mash pH, ideally 5.2–5.4. It is partially because of this comparatively low pH that the first wort is low in tannins (and silicates). Also, as your nose can confirm on any brewday, the first wort is highly aromatic — it smells intensely of malt.
If you batch sparge, there is a discrete boundary between your first wort and your second wort (and perhaps also your third wort). They are collected separately, even if they end up in the same kettle. If you continuously sparge, the first wort blends into the second, sparged wort at some time early in the runoff. In either case, sparged wort — and especially the final runnings in the case of continuous sparging or the third wort in the case of batch sparging — has the following properties, compared to first wort. Sparged wort is lower in specific gravity and proteins. The latter is evidenced by poor break formation in beers made from sparged wort. The pH is higher, and can fall in the 5.5–5.8 range. Because of this, sparged wort is more tannic (and also has more silicates). You can confirm the presence of tannins simply by tasting the final runnings in a continuously sparged wort. You will also notice that sparged wort is much less aromatic than first wort.
As I mentioned, wort made solely from sparged wort often shows weak break formation. The lack of protein in the wort may stress the yeast and lead to an unordered fermentation, sometimes with the production of off odors. In addition, the resulting beer lacks in malt aroma and usually tastes grainy, if not feeling outright astringent. However, there is a way to fix this problem — blend in some first wort.
Making a Worthwhile Second Beer
There are a variety of ways you can improve the sparged wort to the point that a worthwhile second beer can be made from it. If you’ve collected both worts and have them both sitting side by side in different kettles, the obviously solution is to take a portion of the first wort and blend it into the sparged wort. (Likewise, I would argue that blending some of the sparged wort into the first wort will improve it’s quality, at the expense of decreasing it’s specific gravity. But I’ll save that argument for another article.) Another obvious solution is add malt extract — condensed wort — to the sparged wort. This helps in some respects, but does not always yield a beer with sufficient malt aroma.
Brewers who batch sparge could stir some extra crushed malt into their grist when they add the sparge water. After letting the new grains be mashed, they could run off the second wort. If they only had one wort chiller, the time spent mashing could be a positive thing as the batches would be staggered.
In a somewhat similar fashion, and regardless of how you lauter, as the sparged wort is being collected, it could be heated slightly and a bag of crushed grains could be “steeped” in it. This would essentially be making a BIAB beer using sparged wort as brewing liquor.
If you continuously sparge, you can collect the first few gallons of first wort. Then, when the specific gravity starts dropping, collect the remaining several gallons of sparged wort. You’ll always have a larger volume of sparged wort than first wort. After collecting the worts, you can blend them.
However, you can also do the blending on the fly. For example, imagine that you’ve divided the wort collection period into three periods. During the first time segment, you run off wort to the first kettle for 2 minutes for every minute that you run off wort to the second kettle. In other words, in the first time period, you end up with one kettle having twice the volume of first wort and early wort, compared to the second kettle. For the middle time period, direct wort to the first kettle and second kettle evenly — for every minute of wort the first kettle receives, the second kettle also receives a minute’s worth of wort. (Obviously, we’re assuming the flow rate to be roughly constant during wort collection.) Finally, in the final time period, give the first kettle a minute’s worth of wort for every two minutes the second kettle receives. The end result will be equal volumes of wort, with each kettle being a blend of first, middle and late worts. The first kettle will have a higher proportion of first wort and a lower percentage of late wort, with a correspondingly higher specific gravity.
In tomorrow’s article, I’ll give some examples giving volumes of wort and their specific gravities for two different scenarios. In the first, we’ll look at brewing a small volume of big beer from the first wort, but using enough first wort to rescue the much larger second wort. In the second, we’ll look at brewing roughly equal volumes from two worts at different intermediate gravities.