Background: A friend of mine does ten gallon batches of big beers, so has a lot of grain. After mashing, his technique is to fly sparge with 170 degree water. I understand this shuts-down enzymatic conversion. He'll run out of sparge water, drain maybe 2/3 of the liquid from mash tun, and then lets me do whatever I want with the mash tun in order to make a second-run (partigyle) beer.

What I do during his sparging is to create a separate small mash with two pounds of two row, and get the enzymatic activity going well there. Then, when the large mash tun becomes available, I adjust the temperature there to normal mashing temperature again (in the 150 F range), then mix in my small mash with the active enzymes (and enough appropriately heated water to mix in and come to rest at normal mashing temperature).

The Question: Will the enzymes in the small mash that are added to the large mash cause enzymatic activity in that grain that, earlier, had been "too hot"? I realize that the first large mash did most of the conversion. This question is about what is left. Will the enzymes in the small mash have a positive effect on the conversion of grains from the original mash?

Please only answer if you include references; we all likely have our ideas in the range of "probably should" or "probably shouldn't" get conversion going in the old grain, but I'm looking for something more definitive, a why it will or why it won't work, if at all possible. Also, not interested in comments or suggested changes about the background...that's just the way it is, and what I have to deal with.

  • You know I tried to write a couple answers to this, but I wasn't sure if my 14 years of brewing experience and my professional training as a biochemist and enzymologist really counted as I wasn't going to be able to include a reference to what you want. Add to that you didn't tell us how big your buddies mash is, how can we leave an answer with definitive explanations when your question lacks critical details? Downvoted
    – brewchez
    Commented Aug 20, 2011 at 19:23
  • I didn't mean to offend you, brechez. Your self-reported resume would have been enough of a reference...quite impressive. I was just trying to avoid uninformed opinions (I've seen quite a few 'answers' here that fall into that category). As for the details, all you need to to is ask :) I didn't think it mattered that much (thought 10 gallons and "big beers" covered it). But he usually has enough grain to make a 8% to 10% beer.
    – Dale
    Commented Aug 21, 2011 at 13:24
  • All I need is one lurker: Please up-vote to make up for the unfair down vote. Please :)
    – Dale
    Commented Aug 21, 2011 at 23:43
  • I edited your post so I could change the vote.
    – brewchez
    Commented Aug 22, 2011 at 11:12
  • It sounds to me like you're expecting the enzymes in the fresh malt to convert starches in the spent mash. But why would there be uncoverted sugars in the first mash? Commented Aug 24, 2011 at 3:33

3 Answers 3


Well, I don't have references. But I do know that when enzymes are "inactivated" by heat they are irreversibly denatured, destroying them. I'm not sure precisely what you want to have clarified, but the fact is that the only active enzymes will come from your uncooked, active mash. You cannnot "reactivate" the destroyed enzymes.

  • That's good info, logical, and fits with the small knowledge base I have. Those enzymes in the original mash are goners, for sure. What I was looking to have clarified was if the enzymes in the active new mash will spread-out and convert anything left in the original mash's grain.
    – Dale
    Commented Aug 21, 2011 at 13:30

The amount of enzymes contributed by only two pounds of additional 2-row is quite small in comparison to the size of the mash you are adding them too. Conversion is possible, but time-to-convert will be long due to the big dilution of enzymatic activity happening.

So the small amount of enzymes added are capable of doing some additional conversion, but at the cost of extended time. Remember that you also need those enzymes to convert the 2 pounds of small mash as well.

I don't see that your proposal will hurt, but I don't see that it helps much either.

  • By buddy usually ends his brew sessions late in the evening. I'd like to figure out a simple RIMS system that would maintain temperature over night and I could start my boil the next day. Like you say, it's a matter of time. As I understand it, the enzymes are not "used up", they just do their thing, then move on to another sugar chain. Yes, there's only so much convertible material left, but that's sort of the fun for me, to turn something someone was going to throw away into beer.
    – Dale
    Commented Aug 26, 2011 at 0:56

There's a guy that does some really informative youtube videos BobbyFromNJ, and I posed a related question:

Are Enzymes Floating Around in the Mash?

I've watch a few of your videos. Thanks. If you have a minute, I wondered if you could answer this for me.

Say I have a mash that's been sparged with 170 F water (denatured), and another mash I make fresh that settles at 148 or so. If I adjust the temperature of the denatured mash down to 148, then mix in my fresh mash (with the good enzymes) into the other mash, will some of those good enzymes float over to adjacent grain particles and do any conversion at all? If the enzymes are in solution, it would seem to me like they could act on grist from either mash. But if the enzymes stay inside the grain particles, then the only conversion that would be happening would be in the fresh mash, and it's not doing any good to mix the fresh mash with the sparged mash.

And here's Bobby's answer:

Yes, enzymes in a fresh mash will act on any sugar chains they come across. Enzymes do not stay contained withing the endosperm but become distributed in the whole mash including the liquid wort. I've even heard of some folks making up a wort using DME/LME and remashing it with a few pounds of grain in order to make a more fermentable end wort.

If you've watched any of these informative videos, you will probably agree that Bobby knows about the molecular mechanics of the mashing process. So I'm convinced that, given enough time, you would get more conversion than just what the fresh mash alone would have added.

  • @zmccord's post is correct, but doesn't answer the question. Frankly, I sort of like my own answer, but it's not got any up votes. Am I the only one that likes it?
    – Dale
    Commented Aug 26, 2011 at 0:50

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