Partial Mash - Sparge water

[Kristoffer]

Hello,

I've been doing extract brewing up until now, and I would like to try out partial mash to be able to brew a more complex porter then I currently is able to do.

Batch size I'm aiming for is 23 liters, and I'm using a 36 liter pot to boil.

I'm going to use 3,4 kg of malts (2,0 kg base malt + 1,4 kg special malt) so I think 12 liters of mash water will be sufficient.

My question is how much sparge water will I need? Does it have anything to say if I use to much sparge water? What is the minimum amount of sparge water needed?

Also I'm thinking about filling up with water after mash and sparging is complete so I reach my desired boil volume. Then I will add DME to reach desired OG. Is this OK?

Another question. The recipe I'm using is an all grain recipe. It doesn't say anthing about efficiency, but do I have to use more special malt since I'm going for partial mash and it might not be as efficient?

 

[Happywanderer]

Had to convert to real numbers...

So you are shooting for a 6 gallon batch in a 9.5 gallon pot.

And you want to mash with 7.5lbs of grain in 3 gallons of water... 3 gallons = 12 quarts. So that is a mash thickness of about 1.6qt/lb which is great.

So now for sparge. You are probably going to want to shoot for quite a large sparge volume in order to hit target boil volume. 3 gallons (12l) of mash water will probably yield 2.5 gallons (9.5l). This means you want an additional 5 gallons (approximately) in the pot to end up with a total starting boil volume of 7.5gallons.

7.5 gallons after a 60 minute boil should be around 6 gallons. Give or take a bit.

When you sparge - you'll get just about the amount out that you put in... so if you need 5 additional gallons in the boil pot - then I'd go with just over 5 gallons of sparge water.

 

[Happywanderer]

A note - with that volume in your pot - be wary of boil overs... keep your hand on the dial to control the flame...

 

[Kristoffer]

Thanks for answer!

What temperature should the sparge water be? Min-Max?

 

[MrHadack]

Thanks for answer!

What temperature should the sparge water be? Min-Max?

I typically sparge around 77-83 C (170-180F).
More important than temperature when sparging is the water's pH. More alkaline water (pH above 6 in this case) will have the effect of extracting tannin from the grain husks. Keeping the sparge water under that number will defend against this. I typically modify the sparge water to a pH of 5.7.

 

[IslandLizard]

Since you're partial mashing I want to add a few notes on sparging with a "larger volume" of water than "usual" because you're not using a full grain bill. I assume you're batch sparging, it's the easiest and fastest.

Typically you would do 2 sparges of equal volume for best efficiency. After you drain the mash completely, this will be your highest gravity wort, for example, the gravity is 1.080 (@ room temps). To sparge you add your intended 9 liters of water, stir well and drain. The gravity of those 2nd runnings may be between 1.020-1.040 depending on your grist bill. Repeat... but this where it gets tricky. You don't want the gravity of that last sparge to fall under 1.010, or again, you'd start risking tannin extraction. So to keep it easy, I would add no more than half of that (~4 liters) first, stir and drain some off and measure the gravity (@ room temperature). If it's at 1.010 then that's all the sparge water you should use, no more. If it's lower, you're oversparging already, not a big deal, but make a note for next time to use less water in the first sparge, so you have more for the second. If it's higher than 1.010 you can safely add more sparge water. How much depends on that measured gravity of course. Chances are 9+9 liters of sparge water is too much.

This may sound complicated, but once you know and understand the mechanisms and parameters to work within, I hope it makes sense.
To keep the pH in check, most sparge waters benefit from a slight acid addition (phosphoric or lactic acid) to counteract the rising pH of the thinning mash. We're talking less than a ml to perhaps as much as 5 ml (85-90% acid) in a 23 liter batch.

Unless you have a pH meter (strips are inaccurate) you really don't know what the pH in the tun (or kettle, pot) is, so you need to estimate. Bru'n water and Brewer's Friend have excellent mash water calculators/estimators. It has all to do with buffering capacity and alkalinity of the grist/water combo in the tun. The less there is to extract, the less the buffering capacity, the more the pH can fluctuate. The actual pH of your (sparge) water is mostly irrelevant, it's the amount of acid (protons) it contains to counteract alkalies.

Lots more information on this in the brew science forum.

Added - Alternative:
Forgot to mention this, for partial mashes it makes more sense to sparge only once with the full amount of water to get to your pre-boil volume. pH is still an important factor, but it's less finicky as you won't exhaust the grist as easily. A small acid addition should put your pH right on the <5.8 target.

 

[IslandLizard]

Although for some beers a full boil is desired (like IPAs), it's definitely not needed for every beer. A reduced volume brew can be just as good, particularly when you won't be adding your extract until flameout, so you will be boiling with reduced gravity anyway and get good hop utilization.

You can add your top off volume in the kettle either after chilling or in the fermentor, to get to the desired gravity. I emphasized gravity because volume is really a secondary factor when it comes to beer, IMO.

With Porters and Stouts you may still want to steep (and sparge) your dark grains (say 150L and up) on the side, instead of adding them to the mash. Lower temp steeps (120-150°F) reduce astringency and the dark liquor can be added toward the end of the boil (at flameout or with 5 minutes left, to pasteurize) to avoid cooked coffee flavors giving a fresher taste. You will have to mill them separately of course, which you've got to specify very explicitly and still watch like a hawk they don't throw them all in one bag, if you don't do it yourself. I hate mixed grains, there're always a few questions lingering around.

 

[Kristoffer]

Hmm.. Ok. I'm getting a little confused.

I usually add the extract when the wort starts to boil, not at the flame-out. Should I not do this?

So I guess I should boil full volume since I add extract at the start of the boil. This is at least the way I'm used to doing it.

But regarding the sparge. I've heard some say I can just use 2-3 liters of sparge water. Maybe this is a safer way to go, then just add the rest of the water directly into the wort? Also I thought when pouring sparge water over the mash bag I was not to stir the malts, just pour it gently over, and let it drain?

 

[Yooper]

Hmm.. Ok. I'm getting a little confused.

I usually add the extract when the wort starts to boil, not at the flame-out. Should I not do this?

So I guess I should boil full volume since I add extract at the start of the boil. This is at least the way I'm used to doing it.

But regarding the sparge. I've heard some say I can just use 2-3 liters of sparge water. Maybe this is a safer way to go, then just add the rest of the water directly into the wort? Also I thought when pouring sparge water over the mash bag I was not to stir the malts, just pour it gently over, and let it drain?

I really like the results of using only about 1/2 the extract at the beginning, and the rest at flame out- it gives less of a 'cooked extract' taste and a much cleaner beer.

You can mix/stir your grains while you pour sparge water over them, no problem. Then give them a squeeze to get the liquid out- no need to be gentle or let it drain slowly.

I'd not 'oversparge' though. Use 1.5 quarts of water per pound of grain in the mash, and then about the same to sparge, and if you need more water then just top up with water in the boil kettle. That way you don't risk having the pH rise or anything like that. If you're using just a few pounds of grain, you'd have to add water to the boil kettle but that's just fine. In fact, you can start that water on the heat sooner if you want and then just add your mash and sparge runnings to that, so you can get to a boil faster.

You really can't do this 'wrong', so don't worry about it so much!

 

[d3track]

Give this a quick watch
http://brewingtv.com/episodes/2011/2/7/brewing-tv-episode-31-brew-your-own-bender.html

 

[IslandLizard]

Sorry, I didn't mean to confuse you.

If you do full boils you can boil all extract for the full time (60'). But there will be additional caramelization as well as flavor and color changes and reduced attenuation (higher FG). Many who read HBT (and other active sites and blogs) have come to learn to ignore kit recipes and will add 1/3 to 1/2 of the extract at the beginning of the boil, the rest at flameout. It stays fresher (tastes less cooked) and there's less caramelization and darkening. The wort also stays more fermentable. All positives unless you are doing Old Ales or Barleywines.

Sparging means rinsing the sugars of the grains, and you'll need plenty of water for that. Generally at least as much as your strike water. Any sugars left behind are wasted, unless you reclaim them for other purposes, like baking bread or so. Those lost sugars reduce your efficiency, which means you need to use more grain to achieve your gravity.

Those who BIAB mash thin and usually don't sparge or only a little by pouring water over it. They do squeeze the bag and let it drip out as much as gravity and time allows. BIAB is not a bad idea for partial mashes either, if that's what you're doing, I didn't see that mentioned before. When a BIAB brewer doesn't sparge a lot (pouring a gallon over a 20# sack), that bag still contains some good sugars at or near pre-boil gravity. Hopefully at low volume if he squeezed it well. So don't be fooled whatever you read, use common sense. A better, more thorough sparge should get those out, and some do. A partial mash bag is also smaller and easier to handle than a full mash one.

Have you read Palmer's How to Brew?

 

[Kristoffer]

I've read some of it. I'm gonna look more into it. I'm using dried malt extract. Don't know if that matters when it comes to adding it at flame-out? I might try add 1/2 pre-boil and 1/2 at flame-out.

Thanks for your help. I think I got a pretty good idea of how I should do it now. Just hope I manage to hit my OG