baffled by small amount of wort extracted (relative noob)

steve williams · Oct 29, 2024

Hey folks.

Second use of my 30l gear and got into an all grain Vienna IPA and it all seemed to go pretty smoothly, I say 'seemed'..

I followed the recipe to a tee and used around 13l of liquor for a 90minute mash and then 13l for the sparge, tasting the grain I was pretty pleased with the extraction and i got reasonably close (a little short) of the target OG of 1057 for a 5.8% ABV. The boil was 60 minutes with 3 hops added at stages and I achieved a nice rolling (not to aggressive) boil.

HOWEVER, after crashing and added to the fermenter and was dismayed to see a measly 12 litres of wort! The recipe seems to indicate I should end up with 23 litres from 26 litres of liquor.

I've double checked everything on the recipe, the waste grain and hops i removed weren't all that wet, maybe I could have got a tad more out of the waste but I didnt want to be overly aggressive squeezing out anything in case I extracted any nasties.

I am baffled, so I need to find out what I did wrong, if anything, before I mess up (if I did) the next batch.

Thoughts?

Best wishes Steve

Stu's Brews · Oct 29, 2024

Sounds to me like you haven't properly accounted for your losses during the brewing process, as I'd be very surprised if you were able to get 23L fermenter volume from just 26L of liquor.

I use around 30L of liquor to make a 20L batch:

~4L are lost to absorption by the grain.
~3L are lost to evaporation during the boil.
~3L are lost to trub, chiller, boiler losses (i.e. everything that is left behind in the kettle).

The Baron · Oct 29, 2024

IMO 26ltrs is not enough to get 23ltrs of wort after boil.
26ltrs - losses to 1hour boil off and grain absorption loss plus the other incremental losses.
I would think a total volume of somewhere near 34ltrs is nearer the mark.

steve williams · Oct 29, 2024

thanks guys, all makes perfect sense. I think I am being distracted by the recipes target end volume, it doesn't seem right in retrospect. Maybe 12 litres from 26 is 'reasonable' if not great.

I did get close to the target OG so if I had chucked in more liquor (at the start) I may have gotten closer to the volumes the recipe declared, but no way would it have reached 1057, there was around 5.5kg of grain, looked about half what I had when I made a stout the other week.

Larse · Oct 29, 2024

The 13L of strike water would seem a tad low. There would be some dead space in most mash kettles, meaning the mash could be quite dry and that could also explain undershooting your OG.

Rwilts · Oct 29, 2024

What boiler are you using ? Also worth getting brew father or similar, that will tell you mash,sparge water quantities per recipe

Stu's Brews · Oct 29, 2024

steve williams said:
thanks guys, all makes perfect sense. I think I am being distracted by the recipes target end volume, it doesn't seem right in retrospect. Maybe 12 litres from 26 is 'reasonable' if not great.

I did get close to the target OG so if I had chucked in more liquor (at the start) I may have gotten closer to the volumes the recipe declared, but no way would it have reached 1057, there was around 5.5kg of grain, looked about half what I had when I made a stout the other week.

If you are using 5.5kg of grain then you should really have at least 14.85L of water in the mash (2.7 l/kg, which is considered to be a good target), plus whatever deadspace you have at the bottom of the mash tun (this is 3.5L on my Grainfather G30).

As @Larse said, if you have a very dry mash then your mash efficiency will take a hit, so you actually extracted less sugar than intended. However, because you also ended up with less wort than expected it all balanced out to give you the correct OG.

steve williams · Oct 29, 2024

thanks again all, really appreciate the detailed and very quick responses.

This 'dead space' thing... I'm unfamiliar with the concept. The recipe suggested 2.5l per kg, which sounds low based on what I read, but there was no mention of additional liquor to compensate for for mash tun 'dead space'. This is obviously 'a thing' I am clueless about and need to get my head around.

Until I get my head around it I would be nervous about adding more liquor to address 'dead space' in case I over dilute the recipe. Any info / links etc on dead space and what its all about greatly appreciated, it sounds like its a basic buffer depending on the tun to add to all recipes if I'm getting it.

The Baron · Oct 29, 2024

Where did you get the recipe from is it a kit and what system are you using if a AIO or was is BIAB

Agentgonzo · Oct 29, 2024

Agree with the others above.
For reference, one of my recipes as an example is (I picked one roughly similar to yours):

5.4kg Grain
18L mash liquor
13L sparge liquor
OG 1.054
21L into the fermenter
(total losses from input liquor is 10L).

So not too dissimilar to you losses, but I boil gently so don't lose a huge amount in the boil, and also try to reduce the deadspace/trub losses too. 13L strike liquor does seem very low unless you are using sugars.

Larse · Oct 29, 2024

steve williams said:
thanks again all, really appreciate the detailed and very quick responses.

This 'dead space' thing... I'm unfamiliar with the concept. The recipe suggested 2.5l per kg, which sounds low based on what I read, but there was no mention of additional liquor to compensate for for mash tun 'dead space'. This is obviously 'a thing' I am clueless about and need to get my head around.

Until I get my head around it I would be nervous about adding more liquor to address 'dead space' in case I over dilute the recipe. Any info / links etc on dead space and what its all about greatly appreciated, it sounds like its a basic buffer depending on the tun to add to all recipes if I'm getting it.

Dead space is the volume of liquid under your malt pipe. It's basically the amount you have to fill before you start getting your grains wet. Easy to calculate, just get your mash kettle and insert your malt pipe and then fill with a known volume (say a litre at a time) until you see water appear through the bottom of the malt pipe.

Then add that amount to the volume you calculate for your grain bill (2.5 to 3L per kg).

There's no danger of 'diluting'. The greater danger is not having enough mash liquor and under shooting due to a stuck mash or under circulation of liquor. Any over-liquoring can be dealt with in the sparge or boil off.

Edit: Just to add that since you ended up with a small volume of wort at the correct OG means you definitely under-liquored and left a lot of fermentable sugars in the grains you discarded.

Stu's Brews · Oct 29, 2024

steve williams said:
thanks again all, really appreciate the detailed and very quick responses.

This 'dead space' thing... I'm unfamiliar with the concept. The recipe suggested 2.5l per kg, which sounds low based on what I read, but there was no mention of additional liquor to compensate for for mash tun 'dead space'. This is obviously 'a thing' I am clueless about and need to get my head around.

Until I get my head around it I would be nervous about adding more liquor to address 'dead space' in case I over dilute the recipe. Any info / links etc on dead space and what its all about greatly appreciated, it sounds like its a basic buffer depending on the tun to add to all recipes if I'm getting it.

Deadspace is the portion of the mash tun that is below your false bottom and is therefore not in contact with the grains.

steve williams · Oct 29, 2024

Hi again, it was an all grain pre-made kit from Craftybrews if I recall. I mash in an igloo cool box with a domed stainless steel filter

Agentgonzo · Oct 29, 2024

steve williams said:
Hi again, it was an all grain pre-made kit from Craftybrews if I recall. I mash in an igloo cool box with a domed stainless steel filter

The dead space will be the space below your domed filter.

Rwilts · Oct 29, 2024

steve williams said:
Hi again, it was an all grain pre-made kit from Craftybrews if I recall. I mash in an igloo cool box with a domed stainless steel filter

You won't have any traditional dead space I suspect , your mash volume was juts too low...

steve williams · Oct 29, 2024

hi mate, yea i think you're spot on. With this basic set up and a domed mesh filter, there isn't much to worry about below the malt pipe to speak of.

I've just been across and tested it with water, tubing attached, and water starts to flow after i add about 4 to 5 litres to the Igloo, which sounds a lot, but once the syphon starts it sucked almost all of it out and filled a demijohn, leaving not much at all behind.

I'll think twice from now on regarding liquor quantities from recipes and use them as a guide. Larse suggested 2.75l per kg, that would have given me an extra 1.25l to start with and maybe add 2 litres for my small semi dead space.

again thanks for your patience and useful advice, forgive my noobness.

MashBag · Oct 29, 2024

And finally... Don't forget you can top up a fermenter.

SMP Brewery · Oct 29, 2024

Daft question but did where you supposed to sparge it with say another 10/12 litres as you don’t mention it.

steve williams · Oct 29, 2024

just to wrap up.. i did sparge yes, 13l. I didn't do a second sparge.

foxy · Oct 29, 2024

When I used an Esky as a mash tun I put the full volume of mash liquor in, one thing to keep in mind is the temperature of the initial water going in, too hot (to compensate for the transfer of heat) will start to denature the Beta amylase. I didn't go over 66C for the first addition of water then topped up with hot water to the mash temperature.
A piece of 50mm polystyrene cut to fit over the top of the mash wrapped in silver foil will help maintain temperature and don't be afraid to give the grain a good squeeze to get as much wort out as possible.

baffled by small amount of wort extracted (relative noob)

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