Partial Mash Instructions

Methods, ingredients, advice and equipment specific to all-grain (mash), partial mash (mini mash) and "brew in a bag" (BIAB) brewing.

Partial Mash Instructions

Postby Trough Lolly » Tuesday Feb 12, 2008 3:29 pm

G'day all,
A few people have been PM'ing me on my partial mash method. To avoid re-posting it all over the place, I thought that I'd put the information in this topic and if required, the mods can make a sticky out of it...

When I moved from kits and steeped grains to mini mash or partial mash brewing, I didn't have all the fancy brewing equipment such as a Mashtun, Hot Liquor Tank, 50L Kettle and Chiller. Besides, I didn't want to spend a heap of money and find out that it wasn't to my liking.

So I did a partial mash using basic equipment found in most kitchens. To use my method, you need the following equipment:
    Two large pots - one to heat up the brewing water and one for the boil
    A esky of at least 6-pack size,
    A mesh colander or strainer,
    A handheld thermometer, and
    A soup ladle.
The main thing to bear in mind is that unlike steeping, temperature control is fairly important. The key to a good mash is being able to hit the right temperature at the start of the mash. You should aim for 66C and with experience, you can adjust that temperature up or down, to make a fuller or dryer beer, respectively. Now, to achieve the 66C mash temp, you need to take into account that your esky mashtun will absorb some heat, as will the room temperature grains when you dough them into the mash water. For my partial mash system, I used to add the mash water at a strike temperature of 74C and then once I'd added the grains and stirred the lot in, the mash would end up at 66C - your system may vary but after a couple of sessions, you'll know the idiosyncracies of your setup and be able to hit the 66C with consistency. Don't fret about adding grains to very hot water - the temperature will drop when the water hits the mashtun and fall again as you add the room temperature grains.

For the purposes of this post, I'll overlook the recipe and grist, but assume that you have base malt that needs to be mashed in, to allow the amylase enzymes present in the base malt to convert the hydrolised starches present into fermentable sugars.

So, here's my partial mash in the kitchen method:

Half fill the mini / 6 pack esky, with 74C water that's been pre-heated on the stove.

Gradually pour in all of the grains (er, after you cracked them of course!), stirring gently as you go. You eventually want the mixture to have the consistency of soft porridge and a temp in the esky of around 66C - use the coffee kettle or cold water tap to adjust but it's not the end of the world if you're a few degrees either side of 66C. Keep an eye out for doughballs that are easily made in a small mashtun such as this - you need to ensure that all of the grist is soaked with mash water and you don't have any dry spots in the mashtun that will result in poor efficiency and unwanted starch haze in the final product.

Cover the mash and let it sit for 60 mins, stirring every 15 minutes - ignore the inevitable temperature drop - most of the conversion will occur in the first 30 mins anyway.

Whilst you mash for an hour, clean the primary fermenter and if you're using dry yeast, proof it in a clean cup...

Because we're mashing and not steeping, you need to watch your temps. The temperature of the mash will determine which of the two starch to sugar converting enzymes have the most influence on your mash - a mash between 60 to 65C will result in a more fermentable, dryer beer whereas a mash between 65 and 70 will deliver a more malty / dextrinous and fuller tasting beer. I tend to hover around 66C for dry stouts. If your mashtemp is looking like falling below 60C, add around 250ml of near boiling water and gently stir through to disperse the heat - it should bring the mash back up to the 66C mark - repeat if necessary.

As you near the end of the one hour mash, heat about 3L of water to 70C. Place a colander or fine sieve over the second pot (which will be the boil kettle - I used a 12L stock pot). Gently ladle a few scoops of the grains, that have been mashed for an hour, into the colander from the mash esky and drizzle 300ml of 70C hot sparge water over the grains allowing the sweet liquor to accumulate in the stock pot kettle. Eventually you should have collected around 4-5L of sweet liquor (remember we half filled the mash esky and heated up 3L of sparge water). ((Optional: I used to collect the sweet liquor in a vessel and decant it from that vessel into the brewpot via a 1L jug and a muslin bag which would trap the find particulate matter when you poured the sweet wort through it)).

Once finished, you can boil that sweet liquor with half your hops in that pot and use the now empty hot water pot to boil up the extract in your recipe with the other half of the hop bill in about 3-4 litres of water. To add bitterness to the boiled wort, you should boil for at least 30 minutes. I recommend a gentle 60 minute boil. ((Optional: If you have a large enough pot, do a single boil but make sure that the sweet wort combined with the malt extract is topped up to a pre-boil volume of at least 12L otherwise you loose a lot of hop bittering potential with a high gravity boil such as this.))

Note: If you are using a pre-hopped kit as well as extract and grains, you want to keep the hop flavours in the kit so don't add the kit to either boil. The kit can be added to either pot when they are being chilled in the sink. If you add a kit to a boiling wort, all your doing is knocking out the heat sensitive hop aroma and flavour compounds...

When the boil has ended, take the pots over to the sink and fill the sink with cold water - gently stir the wort to whirlpool in one direction and have the outside sink water moving in the opposite, or counterflow, direction to improve the heat exchange. Change the sink water frequently and you'll eventually get the wort below 25C. Splash pour into the fermenter, check temperature and pitch yeast. Seal the fermenter and you're done...

In terms of hygiene, the boil does a pretty good job of holding the bacteria at bay. Just remember that once the boil is over, your wort is vulnerable to infection so make sure that anything that's in contact with the post boil wort (such as your thermometer and destination fermenter) is clean and sanitary...

This method is pretty straightforward and lets you transition to all grain brewing by simply increasing the size of your mashtun...I hope this helps.

Cheers,
TL
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Re: Partial Mash Instructions

Postby Chris » Tuesday Feb 12, 2008 8:11 pm

I can feel a sticky coming on...
A beer in the hand is worth two in George Bush...

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Re: Partial Mash Instructions

Postby Kevnlis » Tuesday Feb 12, 2008 8:27 pm

Got my vote, this link could save us all a lot of typing ;)

Cheers for taking one for the team TL! :lol:
Prost and happy brewing!

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Re: Partial Mash Instructions

Postby drsmurto » Wednesday Feb 13, 2008 9:47 am

Its a thing of beauty.
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Re: Partial Mash Instructions

Postby Chris » Wednesday Feb 13, 2008 9:57 am

The most beautiful of all know beauties...

No hyperbole intended.
A beer in the hand is worth two in George Bush...

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Re: Partial Mash Instructions

Postby drsmurto » Wednesday Feb 13, 2008 10:03 am

Unlike his avatar.... :lol: or mine for that matter
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Re: Partial Mash Instructions

Postby rwh » Wednesday Feb 13, 2008 10:10 am

Hehe I love his avatar... but I prefer yours from AHB... oh I think I'm a little OT...
w00t!
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Re: Partial Mash Instructions

Postby gregb » Thursday Feb 14, 2008 5:44 am

Flicked a couple of posts off to General Discussion "The question had to be asked" thread.

Cheers,
Greg
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Re: Partial Mash Instructions

Postby sonictruth » Thursday Mar 20, 2008 8:46 am

hey TL I have a quick question for you about your partial instructions as im about to embark on my first partial.

I know you avoided talking about the grist in your instructions to avoid confusion but im trying to work out how much grain i can mash in my tun. It is just a 6 can cooler and it fits exactly 5L of liquid. I have read somewhere before that you said 2.3L of water per kg of grain is what you want to aim for. Therefore im assuming that 1.5kg of grain in a 5L tun is about the limit.....is this right? or am i being too generous?

thinking about it now I guess that the grains are going to have a larger volume per kg than water so im probably being a little unrealistic.

do you happen to know what the upper limit is for grains in a 5L vessel? perhaps i should start with 1kg now and get a bigger esky for next time.
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Re: Partial Mash Instructions

Postby Kevnlis » Thursday Mar 20, 2008 8:56 am

I have done 1.5kg mini-mashes in a six-pack esky. 1.5kg of grain will soak up 1.5L or so of water, so it does not actually displace it's weight in volume, if that makes sense?

Only problem is, you need to hit your target first go, if you don't then you will need to remove some of the water from the mash and replace it with boiling water, or boil the liquor you removed.

What I did to help hit the temp was to preheat the esky with hot water to about 5C higher than my intended mash temp. I let it sit for 5 min or so full of the water then tipped it out and put my strike water in. Added the grain, stirred like mad and left it in the sun wrapped in a black wool blanket.
Prost and happy brewing!

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Re: Partial Mash Instructions

Postby sonictruth » Thursday Mar 20, 2008 9:09 am

1.5kg of grain will soak up 1.5L or so of water


of course.....i didnt think of that.

what was your grain to water ratio?
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Re: Partial Mash Instructions

Postby Kevnlis » Thursday Mar 20, 2008 9:12 am

sonictruth wrote:what was your grain to water ratio?


No idea, I just topped it up at the end and shut the lid ;)
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Re: Partial Mash Instructions

Postby Trough Lolly » Friday Mar 21, 2008 10:26 am

sonictruth wrote:hey TL I have a quick question for you about your partial instructions as im about to embark on my first partial.

I know you avoided talking about the grist in your instructions to avoid confusion but im trying to work out how much grain i can mash in my tun. It is just a 6 can cooler and it fits exactly 5L of liquid. I have read somewhere before that you said 2.3L of water per kg of grain is what you want to aim for. Therefore im assuming that 1.5kg of grain in a 5L tun is about the limit.....is this right? or am i being too generous?

thinking about it now I guess that the grains are going to have a larger volume per kg than water so im probably being a little unrealistic.

do you happen to know what the upper limit is for grains in a 5L vessel? perhaps i should start with 1kg now and get a bigger esky for next time.


...further to Kev's good advice, it took a few brews before I knew my mash limits. I found a strike water temp of 74C would give me a 66C mash once all the grains were in. I'd half fill the esky with mash water, add grains and mix then top up with 250ml of mash water in a 1L jug, mix, add more grains, mix, add water etc etc until all the grains were in the esky - I normally got around 2.5 to 3 kg of grains in the esky and it was full to the lid! You don't want too stiff a mash at the start as the grains will absorb water - around 600ml per kilo of grains - and a stiff / thick mash makes it harder for the enzymes to get at the grains, so there's no hard and fast rule but make sure that you have plenty of water ready in case you need to thin out the mash, (but don't overthin the mash as that will hamper the mash too!!). As I mentioned before, the goal is to get all your grains into the mashtun and mashing away at the right temp - you'll probably want to do a smaller mash of 1.5 to 2 kilos of grains at a ratio of around 2L per kilo of grains, until you get more confident at mixing the mash and using more grains. Remember, the gravity can always be helped out by adding some malt extract if you fall short on the pre-boil gravity.

Cheers,
TL
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Re: Partial Mash Instructions

Postby sonictruth » Sunday Mar 23, 2008 9:27 pm

i did my partial on friday arvo and i think all went pretty well. I went for 1.5kg of grain and 2.3L per kg of water. The 6pack esky was pretty full, I dont know if i could up the grain at all for next time, TL maybe your esky was a bit bigger than mine.

my thermometer broke half way thru so im not sure exatly how well i did but i got a reading of 68C after strike (before the themometer broke) so i added a bit of cold water and got it down to 66C. I took the SG before the boil and hit the preboil gravity that was estimated by my brewing software and after all was said and done, my OG before pitching was only 1 point off what it was supposed to be.....good times....

so im not crying success just yet, the proof will be in the pudding (or in the bottle :D ) but im pretty happy with how it went and is really no harder than doing an extract with specialty grains......looks like its going to be AG for me as soon as i can get the gear together :shock: :lol:

thanks for your help guys

josh
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Re: Partial Mash Instructions

Postby Kevnlis » Sunday Mar 23, 2008 10:05 pm

Good on ya Josh! See you on the dark side very soon... ;)

You are right that there is not much difference between steeping, partial mashing and AG mashing. If you have the right equipment it is pretty simple to do and well worth the extra time!
Prost and happy brewing!

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Re: Partial Mash Instructions

Postby Rob C » Monday Mar 24, 2008 1:18 pm

To you guys who use Beersmith where abouts are you able to find your preboil gravity?

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Re: Partial Mash Instructions

Postby Kevnlis » Monday Mar 24, 2008 1:26 pm

Rob C wrote:To you guys who use Beersmith where abouts are you able to find your preboil gravity?

Cheers
Rob


Click the "brewhouse efficiency" button inside the recipe.
Prost and happy brewing!

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Re: Partial Mash Instructions

Postby Rob C » Monday Mar 24, 2008 1:36 pm

Got it Kevnlis thanks heaps mate.

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Re: Partial Mash Instructions

Postby Trough Lolly » Tuesday Mar 25, 2008 11:26 am

sonictruth wrote:i did my partial on friday arvo and i think all went pretty well. I went for 1.5kg of grain and 2.3L per kg of water. The 6pack esky was pretty full, I dont know if i could up the grain at all for next time, TL maybe your esky was a bit bigger than mine.
josh


Congrats Josh - looks like you did fine. Don't sweat efficiencies with a partial mash - with a partial mash, you need to keep an eye on temperature and the rest will fall into place. If you fall short on your pre-boil volume after the mash, no sweat, just top up with water. You need to make sure that you have sufficient boil volume to do the hop bittering.

I must admit that when I first started partials, I'd use no more than 2kg of grain and over time, I'd steadily increase by 250g in each batch until I figured that the mash was too stiff. For a while, I actually used the stock pots for the mash and with the relatively larger volume pots, it was only a matter of time before I was doing batches without kits in the recipe - ie, all grain beer. The loss of thermal heat was easily overcome by giving the pot a quick blast of flame and a good stir every 15 mins...

Cheers,
TL
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Re: Partial Mash Instructions

Postby Rob C » Tuesday Mar 25, 2008 4:19 pm

In the middle of a brew at the moment i have finished my mash and measured my preboil SG beersmith estimated 1.087 and i measured 1.044 can anyone suggest what went wrong here?

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