- This topic has 4 replies, 4 voices, and was last updated 4 years, 9 months ago by Anonymous.
June 16, 2014 at 8:28 pm #16164finnParticipant
Hi all-grain brewers,
I have a problem where I need your help and experience. I am brewing with a combination of the BM20 and the WilliamsWarn. While having made a couple of really nice beers with that combination of equipment I’m facing a regular problem. My FG is usually higher than expected and intended. I hope some of you are also working with the BM20 and the WW and are able to help. Following a couple of details on my last recipe to provide you with a bit of background.
Style: American Pale Ale
Malt bill: Pale Ale Malt 3.3kg; Pilsener Malt 1kg; Munich II 0.4kg; CaraPils 0.4kg; Flaked Oats 0.15kg
Mash size: 23L first Mash + ~7L sparge water = 27L boil
Final volume: 27L
Step mash: 1. 20°C for 3h (for higher effciency in the BM); 2. 38°C for 20min; 3. 54°C for 15min; 4. 64°C for 45min; 5. 73°C for 35min; 78°C for 20min
OG: 1050 at 27L
Chill: No chill first in BM until 75°C are reached than overnight in desinfected Speidel plastic barrel
Volume in WW: ~24L
Airation: ~20min with electric wort airation pump (like aquarium pump)
Yeast: 1 pack Safale US05
Yeast nutrients: 4g Wyeast yeast nutrients 10min before end of boil
Fermentation temperature: 19°C
Fermentation pressure: 2.5bar (I like my beer sparkling)
I left out the information on hops etc. and tried to include all the relevant information.But I’m happy to share the full recipe if anybody is interested.
Now my problem is that my FG is not going where I want it to be. After 5 days in the WW SG is still at 1020 and fermentation has really slowed down. Fermentation started really well and there was massive Kräusen but the yeast has started to settle. I’m not optimistic that the fermentation will knock of another 8 to get me to FG 1012 where I want it to be. So what am I doing wrong? I have thought of a couple of issues thatcould be the source of my problem.
Yeast pitch rate: Maybe too low, but I doubt it since the US05 is really kicking off.
Pressure: Could 2.5bar be too much for the yeast?
Mash step at 64°C: Are 45min too short for a low FG?
Mash step at 73°C: Do I get non-fermentable dextrins at this step?
Grain bill: Too much specialty malt?
Airation: Too short and not enough oxygen in the wort?
General BM problem: Anything that I should do differently with the Speidel BM?
Would be great if somebody could help me out here. I have already poured one batch down the sink (my go at a belgian triple with OG 1080 that stopped at over 1030 and was way to sweet) and I don’t want to experience that again.
Thanks for your help!
FinnJune 16, 2014 at 10:08 pm #16724jeromeParticipant
Blimey that’s a long mash!
Sounds like your pitching rate is fine – I’ve had 1 pack of US-05 eat bigger grain bills than that. Also sounds like you are aerating well. So for my money it’s an under attenuation issue due to too many unfermentable sugars in the wort.
From what I understand, a high mash temperature is one way of extracting additional non-fermentable sugars and you are mashing for nearly an hour at between 73 and 78C. Your mash-out step (I assume that is what you are doing @ 78) also seems too long and hot. I think 76 is hot enough to stop enzyme activity and maybe try just 10 minutes (I never mash out so not 100% on this).
Maybe try keeping the mash cooler – say under 69. The problem is, if you have these unfermentables there is not much you can do in terms of drying it out. I have had the same issue with too much crystal malt and no amount of yeast rousing, re-pitching or champagne yeast shifted it so down the drain it went!June 17, 2014 at 12:51 am #16725roger mellieParticipant
Looks like your grain bill is OK – a couple of things – I won’t comment on your mash schedule 😮
1. How are you measuring your SG? I have found with the amount of free CO2 in the sample that a hydrometer is hit and miss. Try cross referencing with a refractometer if possible?
2. You are saying you are missing your FG – is this based on what Beersmith is saying – this is an estimate based on textbook attenuation – for reference only. Take as a guide only. I seldom hit the Beersmith target.
3. Are you hitting your OG’s and volumes? You say OG was 1.050 @ 27L I assume this was the pre boiled gravity? What was the gravity into the fermenter.
4. Have you upped the Fermentation temp since the ferment has slowed down to try and get the final few points?
5. Have you tried rousing the wort – shoot 20secs worth of CO2 through the additive pot
6. Are you kegging? Have you thought about fermenting under a lower pressure (~1.5 Bar) and adding more gas later?
7. Whats your IBU? Sometimes perceived sweetness is caused by a lack of bitterness.
My thoughts on some of your thoughts
Yeast pitch rate: Maybe too low, but I doubt it since the US05 is really kicking off. Unlikely given your OG – one packet of correctly rehydrated US05 should be fine – where are you storing your yeast?
Pressure: Could 2.5bar be too much for the yeast?Possible[ – not an expert in this pressurised fermentation and its effect on ferment – as an option why not ferment at 1.5 BarG for the first part of the ferment then when fermentation is done and you are clarifying wind the reg up to 2.5 – will have exactly the same effect/i]
Mash step at 64°C: Are 45min too short for a low FG?If you are using freshly milled and good quality grain then 45 minutes should be plenty for full conversion
Mash step at 73°C: Do I get non-fermentable dextrins at this step?Conversion should be complete by this stage – maybe try eliminating this step (add 15 mins @64) then go straight to a mash out
Grain bill: Too much specialty malt?Doesnt look like it in this grain bill
Airation: Too short and not enough oxygen in the wort?Dried yeast generally doesn’t need aeration in any case
General BM problem: Anything that I should do differently with the Speidel BM?Here is where you might be on to something – there is conjecture regarding the boil ferocity (or lack thereof) of the BM – BM themselves sell a hood that ups the grunt of the boil (just like leaving the lid on) but still allow evaporation – for ~10 bucks you can do something very similar with a stainless steel bowl with a 6″ hole cut in the top
Good luck with it – have you also tried just going back to basics – doing a SMASH pils or something very basic (20 Mins at 52, 60 mins at 64 – Mashout – something like 35 IBU’s) and using a good attenuating lager yeast (34/70) with an OG at 1.048 you should get to ~ 1.010 or less.
CheersApril 8, 2015 at 4:02 am #16726dafaa45Participant
Your mash-out step (I assume that is what you are doing @ 78) also seems too long and hot. I think 76 is hot enough to stop enzyme activity and maybe try just 10 minutes (I never mash out so not 100% on this).??April 12, 2015 at 10:08 pm #16727AnonymousGuest
an attenuation problem by an all grain brewer will most likely be not enough conversion of starch into sugars in the mash and then there is nothing to be done about it except perhaps adding enzymes and rousing the yeast or adding new yeast.
The optimal temperatures for starch conversion are 63’C for beta amylase to make maltose (two glucose molecules joined together) and 72’C for alpha amylase to make glucose. The time you need for these rests depends on the enzymic strength in your grains. It could be you’ve got some malt with low enzymes or weak enzymes so you need longer mashing times at these two temperatures. Usually pale ale malt and pilsner malt has plenty of enzymes so a little strange as your times are pretty normal for 2 row malt. In the USA malt has higher levels of enzymes so they have shorter times than Europe and Oceania. A quick fix would be to get some enzymes from your local homebrew and add some to the mash. A ones they sell for diabetics to reduce starch content and get more sugars tunred into alcohol. If it has both of the enzymes mentioned above it’d be best. Or chose malts that are known by other brewers to make beers that get to 1.011 SG for example. Dry yeast don’t need aeration so should ferment all the way. Try Nottingham or S-04 instead of US-05 as these two go quick and all the way quite well. A refractometer only works in wort without alcohol so you need to use a hydrometer. Stick to beers under 1.050 until you sort it out so one sachet of yeast has a chance to go all the way. Ian
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