These days, it seems the most popular mashing method among homebrewers is batch sparge, perhaps due to its simplicity, though this hasn’t always been the case. A decade ago, if someone said they brewed all grain, it was pretty much assumed they were using the fly sparge method. For this xBmt, we compared these commonly used approaches, results are in!
The results are not surprising to me. And fly sparging is definitely the mark of the devil 666 \m/ The number of the beast!
I don’t see a gravity difference of .003 as significant. To me, it’s within the margin of measurement error. And I REALLY don’t think that small amount would make a difference in the perception of dryness as Ray postulates.
Throw in a no-sparge vs. the batch sparge. That would be an interesting take.
I don’t disagree 
You know it’s coming!
Hmm? I wonder if the gravity difference could have been effectively neutralized by diluting the higher gravity brew to equal the lower gravity result and then correct each batch to a uniform pre-boil volume? Then more variables would have been brought into agreement and the effect of the sparging method could be considered a greater contributor to any differences. It otherwise looks to be a good comparative study.
Perhaps for a future reiteration, assuming a difference in OG remains. I’d actually be more concerned diluting would introduce a variable with a potentially higher likelihood of contributing some other character not attributable to mash method.
To me the only real information gained here is that two different systems can make detectably different beer from the same recipe.
This reminds me of the mash temperature experiment - two similar beers but different gravities. In the mash temperature experiment the final gravities were 0.09 apart and 9 out of 20 people could detect a difference (not significant). in the fly sparge experiment the OGs are 0.04 apart and 9 out of 16 people could detect a difference (significant).
Both results hover at the edge of significance - one negative, one positive. The danger is that people start interpreting these results as gospel: you can taste OG differences but not FG differences. I think some caution is needed before any firm conclusions can be drawn. Until replicated the results really aren’t clear cut as there’s a large margin of error in both cases.
Also note unwanted variable of longer mash time in fly sparge discussed in comments. Could have been easily removed by timing the batch sparge.
“Can,” indeed, not necessarily “will.”
I encourage people interpret every xBmt with caution, regardless of p-value. I’m also a big fan of people trying stuff out for themselves, especially a variable like mash method that likely won’t have a detrimental impact. Fun stuff!
Removing one variable by adding another is certainly something we’ll be doing, but I intentionally wanted to establish a simple baseline with this xBmt.
That was my point. I don’t think this experiment tells anymore about batch sparge vs fly than it does BIAB vs fly or your system vs mine. They are different so the same recipe may produce detectably different tasting results.
I suppose that’s sort of the point, if there is a point. Except according to the many who have requested we do this xBmt, it seems many expected no difference, myself included. At the very least, interesting.
Why would making sparging times equal introduce another variable?
Crap, my bad. I was responding to the comment suggesting equalizing OG by adding water to fly sparge batch. I agree with you!
Did he measure the pH of the batch sparges (how many did he do, 2-3?)? My theory with batch sparging is that the second sparge will have a significantly higher pH than the first, as the majority of the buffers have been drained out. The second (and third) will be more impacted by the sparge water alkalinity and pH, resulting in a higher mash pH and subsequently more tannin extraction. With fly sparging, you are gradually diluting the buffering pool and much less time is spent in the higher pH range. In theory, the final pH should be the same, once mixed, so you may not detect it with boil kettle pH measurements.
Also, it looks like a lot more break material was left behind in the batch sparge mash, which could account for some of the differences in the PBG. If that much break material forms, then the second batch sparge must be significantly hotter than the fly sparge reaches. This makes sense, as fly sparging is a gradual dilution with hot water, whereas batch sparging occurs nearly instantaneously.
Hotter temps, combined with potentially higher pH would very likely result in wort quality differences that tasters will detect. Some may have a preference for it, some against it, depending I suspect on what they are used to in their own homebrew.
I don’t think that’s right. If you think of pH in graph terms, fly sparging causes steady rise to a higher maximum after buffering is overwhelmed, whereas batch sparging causes a rise in steps after buffering is overwhelmed or no rise at all if buffering is maintained. With either technique, the idea is to stop before pH rises into the danger zone.
That’s not hot break material, it’s probably just malt flour that’s been stirred up by addition of batch sparge water and then settled out on the grain bed. Fly sparging doesn’t add as much water in one go so causes less sedimentation.
Sorry, but neither of these statements are correct.