Decoction and Mash Out questions

I am planning on doing a vienna style lager this year (now that I have something to control lager temps for fermentation and laggering.) I wanted to start simple and figure vienna style is that.

First is it even necessary to do a decoction with vienna grains? If one didn't do a decoction and wanted a medium body beer, do they just do the single infusion at 154 degrees for an hour or something else? I am tempted to try a single decoction just for kicks, but I wanted to see if it was necessary.

Second (and this pertains to ALL brewing, not just lagers, etc) -- when mashing out, I always tried putting in boiling water into the mash tun but never was able to get enough in to raise the temps to mash out. I always came up 5-10 degrees short because I didn't have enough room in the mash tun. After watching Kaiser's decoction video, I saw he removed some of the mash, brought to a boil and then added back to get mash out temps. Would this work for ANY brew (and not just those scheduled for decoction?)

Decoction is fairly simple to learn but it takes a while to get use to it.

First is it even necessary to do a decoction with vienna grains? If one didn't do a decoction and wanted a medium body beer, do they just do the single infusion at 154 degrees for an hour or something else? I am tempted to try a single decoction just for kicks, but I wanted to see if it was necessary.

Click to expand...

Yes, you can get a medium bodied beer if you do a single infusion and you can also add meladonin malt which will give the effect of a decoction. I have never done this because I find that a decoction is not terribly hard and the efficiency gains are huge.

Mashing out is a tricky situation. Basically, I drain my tun before mashing out and then immediately batch sparge to 168-172 and bring the mash up to a boil very quickly. I want to denature all of the enzymes, this is how I do it. I think it's much easier to mash out if you have the ability to head your MLT (think keggie) but when dealing with a cooler I would not bother to mash out. You can however decoct to a mash out temp if you really wanted to but the big gains come from jumping from 122 to 148, and 148 to 162. I don't want to deal with a 3rd decoction to get from 162 to 168, I just drain and heat. Hope this helps.

I did Bradsul's Vienna lager recipe- it was a double decoction I believe. It's easy, and the beer was rich and malty. It's not necessary, so if you want to skip the decoction you could add .5 pound of melanoidin malt and call it good.

For mashing out, if you're fly sparging, you can just add boiling water to get your grainbed temp to 168 or so. But if you're a bit low, that's ok. You can sparge with hotter water if you need to, but it's not a big deal.

If you're batch sparging, there is no advantage to mashing out.

Adding melanoidion malt to "mimic" a decoction assumes that a decoction does something to flavor. I'm not so certain.

asterix404 said:

Decoction is fairly simple to learn but it takes a while to get use to it.



Yes, you can get a medium bodied beer if you do a single infusion and you can also add meladonin malt which will give the effect of a decoction. I have never done this because I find that a decoction is not terribly hard and the efficiency gains are huge.

Mashing out is a tricky situation. Basically, I drain my tun before mashing out and then immediately batch sparge to 168-172 and bring the mash up to a boil very quickly. I want to denature all of the enzymes, this is how I do it. I think it's much easier to mash out if you have the ability to head your MLT (think keggie) but when dealing with a cooler I would not bother to mash out. You can however decoct to a mash out temp if you really wanted to but the big gains come from jumping from 122 to 148, and 148 to 162. I don't want to deal with a 3rd decoction to get from 162 to 168, I just drain and heat. Hope this helps.

Click to expand...

I don't understand how your process works. The first runnings will contain the enzymes, and they will remain active once you've drawn off the liquid. They will continue to work on the first runnings while you are sparging.

Or am I missing something?

Love the decoction mash. As a rule of thumb I decoct my lagers at least once.

To remain true to style you may want to try decoction mashing. You can do a double decoction, skipping the acid rest if you use 5.2 Ph stabilizer in the water. A pound of grain takes less BTUs to reach boiling than a pound of water, and a pound of boiled mash raises the temperature in the tun better than a pound of water. That may sound weird but it does. What makes a decoction unique, is that the entire mash is taken through all the temperature ranges two or three times. It breaks down more haze forming proteins. It also allows the enzymes to get at the starch easier. Once you try decoction mashing, you'll notice that the water in the decoction mash has a smooth silky feel to it. You'll also notice the difference in the way the spent mash looks as compared to an infusion. I have been doing triple decoction mashing since the early 80's. To me, the extra time mashing and boiling doesn't matter. All my equipment is designed for the decoction procedure and that makes it go a lot better.

thanks for all the replies. I think I will definitely give decoction a try. It does sound very interesting and for me a new twist to brewing. I've probably done 40-50 batches in the last 5 yrs and I need to try something new.

I did my first decoction on a 1 gallon batch of a dark mild, just to try it out. It was really very easy. Just make sure to pull enough mash to raise your temp in the tun. Taking more than you need is better than not enough. There's a good video by Brewingtv that demonstrates the decoction process. Less detailed as Kai's but good none-the-less.
I plan on doing more decoctions in the future. My mild is currently carbing up.

I don't understand how your process works. The first runnings will contain the enzymes, and they will remain active once you've drawn off the liquid. They will continue to work on the first runnings while you are sparging.

Or am I missing something?

Click to expand...

Most anything that will have been able to convert have already converted. The first running I heat up to about 168 in the kettle while the batch sparge is sitting. Even if I didn't heat it up, if there is any conversion happening it is happening for a very short while (say like 20min). Honestly, I think there are more important things to worry about and the big worry about doing a mashout is for fly sparging where it can take a long time to rinse the grain.

At the very least, I haven't had any huge problems or bad beer and I haven't noticed a difference in my system when I have done a mashout via decoction vs. just collecting the wort and bringing it up to a boil while the batch sparge is doing its thing. If you think I should look at this again, I can test it out with a small batch but I think if you do a decoction mash schedule you are basically mashing for about 2h so an extra 10min for it to drain won't really hurt it I think.

The trick for the first time is to basically get the process down, it's a complex process which takes a while to get right but my strong advice is to always take out more than you think you will need since you can always add cold water. It's much harder to heat up you mash unless you have a direct fire.

Here is a simple double decotion that I have done quite a few times now. It's the only way I do it anymore. It boils almost all of the grain. You could even drop the mash out or use an infusion mash out for a single decotion.


If you want to do a protein rest dough in at 130, rest ~20 minutes. Infuse to 140-145 rest 20-40 minutes.

Pull most of the grain out with enough liquid to maintain a rolling boil (this is what gives the efficiency gain by gelatinizing and releasing more starches to the mash.) No need for any rests it will finish conversion in the next step. Boil 10-30 minutes. You have to mash thin so as to keep most of the enzymes in the liquid still in the mash.

Add this in slowly to hit 155-160 (add the extra after it has cooled.) Rest 20-40 minutes.

Last pull most of the liquid and Boil 10-30 minutes. Add back slowly to hit 168F. I cool the rest of the decotion with ice so I can add it in quickly.


Changing the times and temps can make about any fermentation profile. This is nearly the same schedule that I use with a cereal mash.