Low ABV

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m_rawdin
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Low ABV

Post by m_rawdin » Sun Aug 13, 2017 2:08 pm

So I've just finished fermenting a milk stout, I was expecting an ABV of about 6.5% but it's come out at 4.7%. The OG was 1062 and FG is 1026, I used crossmyloof real ale yeast and it seemed to be a perfect fermentation, didn't look like it got stuck anywhere. My maris otter malt is about 6 or 7 months old but can't think where else things might not have gone exactly gone to plan? Any suggestions?
Fermenting: Strawberry beer
Conditioning:
Drinking: milk stout, wheat beer
Planning: Kolsch

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thepatchworkdoll
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Re: Low ABV

Post by thepatchworkdoll » Sun Aug 13, 2017 2:14 pm

Hi MR
That would be about correct in my opinion
1062 - 1026 = .036 x 129 = 4.64%
Hope this help clarify your problem
Regards
Patch

m_rawdin
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Re: Low ABV

Post by m_rawdin » Sun Aug 13, 2017 2:19 pm

Sorry yeah the calculation is fine but was expecting my FG to be a lot lower to get me closer to my expected 6.5%
Fermenting: Strawberry beer
Conditioning:
Drinking: milk stout, wheat beer
Planning: Kolsch

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Sadfield
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Re: Low ABV

Post by Sadfield » Sun Aug 13, 2017 4:06 pm

Have you accounted for the lactose? How much and when did you add it?

Lactose will not ferment out to provide ABV but will raise the final gravity, this can skew the final calculation.

m_rawdin
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Re: Low ABV

Post by m_rawdin » Sun Aug 13, 2017 4:30 pm

Sadfield wrote:
Sun Aug 13, 2017 4:06 pm
Have you accounted for the lactose? How much and when did you add it?

Lactose will not ferment out to provide ABV but will raise the final gravity, this can skew the final calculation.
There was 500g of lactose and 5.25kg of grain for a 20 litre batch. I have a braumeister so don't think anything went wrong on brew day, I added the lactose 15 mins before the end of the boil.
Fermenting: Strawberry beer
Conditioning:
Drinking: milk stout, wheat beer
Planning: Kolsch

m_rawdin
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Location: Newcastle upon Tyne

Re: Low ABV

Post by m_rawdin » Sun Aug 13, 2017 4:31 pm

Oh and I used beersmith to build my recipe. However I just changed my recipe to take out the lactose and the ABV dropped significantly. I thought beersmith would recognise its non fermentable?
Fermenting: Strawberry beer
Conditioning:
Drinking: milk stout, wheat beer
Planning: Kolsch

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Sadfield
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Re: Low ABV

Post by Sadfield » Sun Aug 13, 2017 4:54 pm

Looks like fermentation has stalled. You only achieved 57% attenuation from a yeast that should be in the mid 70s. How many packets of yeast? IIRC cmg comes in 10g packs and is supposed to be "similar" to Lallemand Nottingham that requires pitching at 1g for every Liter of wort.

m_rawdin
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Re: Low ABV

Post by m_rawdin » Sun Aug 13, 2017 4:59 pm

Sadfield wrote:
Sun Aug 13, 2017 4:54 pm
Looks like fermentation has stalled. You only achieved 57% attenuation from a yeast that should be in the mid 70s. How many packets of yeast? IIRC cmg comes in 10g packs and is supposed to be "similar" to Lallemand Nottingham that requires pitching at 1g for every Liter of wort.
I have a feeling maybe I was a bit low on the yeast and should have put 2 packets in not just 1
Fermenting: Strawberry beer
Conditioning:
Drinking: milk stout, wheat beer
Planning: Kolsch

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Sadfield
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Re: Low ABV

Post by Sadfield » Sun Aug 13, 2017 5:12 pm

m_rawdin wrote:
Sun Aug 13, 2017 4:59 pm
Sadfield wrote:
Sun Aug 13, 2017 4:54 pm
Looks like fermentation has stalled. You only achieved 57% attenuation from a yeast that should be in the mid 70s. How many packets of yeast? IIRC cmg comes in 10g packs and is supposed to be "similar" to Lallemand Nottingham that requires pitching at 1g for every Liter of wort.
I have a feeling maybe I was a bit low on the yeast and should have put 2 packets in not just 1
I estimate you have less than half the amount needed. What is the needed cell count under the Starter tab in Beersmith, I estimate around 225 Billion Cells. Probably around 100 Billion in your packet.

Maldon John
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Re: Low ABV

Post by Maldon John » Sun Aug 13, 2017 9:37 pm

m_rawdin wrote:
Sun Aug 13, 2017 4:31 pm
Oh and I used beersmith to build my recipe. However I just changed my recipe to take out the lactose and the ABV dropped significantly. I thought beersmith would recognise its non fermentable?
I take it you ticked the " non- fermentable " box in " edit grain details" for the Lactose in Beersmith?

m_rawdin
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Re: Low ABV

Post by m_rawdin » Mon Aug 14, 2017 9:54 am

Maldon John wrote:
Sun Aug 13, 2017 9:37 pm
m_rawdin wrote:
Sun Aug 13, 2017 4:31 pm
Oh and I used beersmith to build my recipe. However I just changed my recipe to take out the lactose and the ABV dropped significantly. I thought beersmith would recognise its non fermentable?
I take it you ticked the " non- fermentable " box in " edit grain details" for the Lactose in Beersmith?
Ah no I didn't, I just assumed it would already be in as a non fermentable, that's made the ABV much closer to where I'm at! Thanks for everyone's help and advice!
Fermenting: Strawberry beer
Conditioning:
Drinking: milk stout, wheat beer
Planning: Kolsch

steveshep8676
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Re: Low ABV

Post by steveshep8676 » Tue Aug 29, 2017 7:05 pm

Just read your post on low ABV what's been said is correct but also something to note is the mash temperature. If it was up around 67c or more you're producing mainly long chain sugars maltriose and dextirins which are very difficult for the yeast to ferment.


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