Ultimate Efficiency

Posted on 02.24.10 8:12PM under All-Grain, Brewing

As a brewer, extract efficiency is a key metric. Each grain you use in your brew has a certain amount of potential sugar stored in there. Due to our limitations as humans in the real world, we can’t really get all that sugar out. So extract efficiency measures the percentage that we do manage to run off into our kettles.

Maximizing this number gives you the ability to get the most out of your grains. This saves money and expands the possibilities of what you can make without needing to add sugar or malt extract. Consistent efficiency allows you to craft more precise and repeatable recipes.

Efficiency relates to many variables, including how you crush the grains, mash filter arrangement, possibly mash thickness and duration, and so on. Most of these are pretty constant from batch to batch. But my efficiency has been hovering around a meager 65-70%. This is not where I want it. It’s OK, but it seems to leave a lot on the table (or in the tun, so to speak).

I targeted sparging as the process step with the greatest opportunity for improvement and I have found a consistent high-efficiency method: no-stir batch sparging.

Sparging is the process of rinsing sugar off grains from the mash. Batch sparging is the process of removing all water from the mash, and refilling the mash tun and running off all the water again. This is repeated until the kettle is full of wort. Normally two to four batches total, depending on how many pounds of grain you’re using. The alternative is fly sparging, where water is continuously added to the top of the mash at the same rate as it is drained from the bottom of the mash.

It seems counter-intuitive. You’d think that continuously sparging would be effective, maybe just because it takes more human intervention. You’d think that, given batch sparging, by stirring in between runoffs you’d expose more surface area of the grains to water, and thus aid in extraction. But you’ve got to trust the data, and my recent experiments show no-stir to be the way to go. Stirring my batches: around 75% efficiency. No-stir: 88% efficiency.

Jeremy, my chemist friend and co-brewer thought it might be better without stirring, and it turns out he was right!

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