Brewing all grain, my mash tun can't hold my full sparge volume. So I step it, a few gallons at a time. I've read that the sparge water should be 170 F to stop the enzyme reaction. But when stepping my sparge, do the later steps need to be 170, or just the first step to stop the enzymes? Can the enzymes restart between steps?

Per the comments, by step batch sparge I mean a batch sparge of 5 or 6 gallons, in steps of 2 or 3 gallons, repeated to get to the boil volume.

  • 1
    What exactly do you mean by 'stepped'? Do you mean that you: mash; run all the liquid off; add a few gallons of hot water; run all that liquid off; then repeat the last two steps until the water is gone? Mar 23, 2015 at 18:16
  • In a way, yes. My first runnings gives me 2 or 3 gallons. I can only realistically fit 3 gallons in the batch sparge, and I need 7 or 8 gallons to boil. So I batch sparge twice with 3 gallons. The 'batch' is done in steps
    – CDspace
    Mar 23, 2015 at 18:20

1 Answer 1


I'm going to assume you're basically doing "batch sparging" (adding the sparge liquor in batches due to capacity), not that you're "step mashing" (using hot water infusions to move the whole mash through a set of different temperature "steps").

Once the enzymes are denatured, they are … denatured. :) They will not return or restart their ability to convert starch to sugar once they get too hot and are destroyed.

That being said, only your first infusion would need to be a mash-out infusion. Assuming you've already mashed at the appropriate temp (145-156) and for an appropriate length of time (45-60 minutes), you can then do a mash out, and your subsequent batch sparges are just going to rinse the already-converted sugars from the mash, not do any more conversion.

I will note that doing a mash-out is an ideal practice particularly for repeatable results and promoting lower mash viscosity, but certainly not required.

  • What do you mean by 'doing a mash out' at the end of your answer? And your assumption is correct. I was tired of waiting for the sparge temp to hit 170 each time, and wondered if I could sparge the later steps sooner
    – CDspace
    Mar 23, 2015 at 18:29
  • I've only done one recipe that called for a step mash, and this wasn't it. The step mash was easier, as the recipe gave me the volumes, temps, and times, nothing to question there
    – CDspace
    Mar 23, 2015 at 18:32
  • A "mash out" is the process of heating the mash to >167°F to denature mash enzymes and make the mash liquor a bit less viscous, to promote easier runoff. Yes, you can just mash out in your first sparge batch, and drain normally later. Or, just not worry about doing a mash out.
    – jsled
    Mar 23, 2015 at 19:19
  • 2
    If you're interested in using the first 'sparge' to halt enzyme activity, you might want to make it hotter than 170°F. Some rough calculations show you'd need to add 8-10 times the weight of the saturated grains left in the mash tun (assuming they're 150°F) in water at 170°F to reach a mash-out temp of 168°F. If the water was 178°F you'd only have to add less than twice the weight to hit the same target temperature. Mar 23, 2015 at 19:41
  • 2
    Differentiate between the temperature of the water and the temperature of the mash. You want the combined mash to be above 170 for a mash-out, and you really don't want to go much past that, to prevent tannin extraction.
    – jsled
    Mar 23, 2015 at 22:56

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.