Stuck Fermentation or High Final Gravity

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campbellpotter

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Hi, I have weird fermentation going on that I would appreciate some advice on.

Here is the Recipe

Pale 2 Row Malt - 5kg
Munich Malt - .45kg
Caramel/Crystal Malt 40L - .43kg
Carapils - .23kg

It is an IPA so has numerous hops in the boil and some dry hopping but I don't think that is relevant for this issues, I can update if you think it is.

I used a Boil in the Bag technique and got 22 Litres of wort with an OG of 1048. The temp was a bit high for the BIAB about 75D to start and it dropped to 68D after 90mins when I starter the boil. I used Saflager 23 that I harvested from my last batch with a 1 litre yeast starter to kick it off.

I have been fermenting this in my fridge at about 18D. I was planning on keeping it lower about 12D but the fermentation was so slow that I thought a bit higher would help it.

After 7 days SG was at 1028 and this is where is stayed for 5 more days. I looked on forums about stuck fermentation and tried to repitch some yeast. So made 1 litre yeast starter out of another Saflager 23 dry yeast packet and pitched this.

After 7 more days it was at 1025???

I thought that it this must be the final gravity so dropped the temp to 4D and did the last dry hop.

Now after another 10 days at 4D soaking up hops the gravity has dropped to 1016??? I plan to bottle it as it is at this stage unless I shouldn't.

My main concern is that there are still unfermented sugars in the wort and that I will create a batch of bottle bombs.
 

progmac

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this is exactly the type of beer that tends to make bottle bombs. those 'unfermentable' sugars tend to get eaten slowly over the course of several months and eventually you can have a real bummer of a batch.

i would let it age at room temperature for a month and see where you're at.

another idea is to use some Amylase enzyme to further break down sugars. Some people use the product called bean-o which contains this. Food for thought and an area where you can do more research if you're interested.
 

Calder

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It will not drop from 1.025 to 1.016 at 4 C (40 F). Once you crashed, the yeast will quit working.

Seems like one of the readings is wrong.

Mashing at 75 C (167 F) and dropping down to 68 C (155 F), I think would result in an unfermentable wort, giving you a high FG.

Just make sure it is stable before bottling.
 
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campbellpotter

campbellpotter

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It will not drop from 1.025 to 1.016 at 4 C (40 F). Once you crashed, the yeast will quit working.

Seems like one of the readings is wrong.

Mashing at 75 C (167 F) and dropping down to 68 C (155 F), I think would result in an unfermentable wort, giving you a high FG.

Just make sure it is stable before bottling.
That was what I thought and why I was surprised with the different readings. It was steady before at 1028 for about 10 days I guess I should wait a few more to see if drops again or steadies at 1016.

I 1016 seems like it may be the finished as the higher mash temp would make more unfermentable.
 
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