Stalled fermentation, pitched more yeast, and added DME.......

[Alex.mc]

Okay, bear with me...
I did a stout recipe, and got an OG of 1.057. Pitched the yeast and got some good bubbling etc, left it 2 weeks, measured and the FG was at 1.030. Waited another week, no movement, Pitched a new sachet of yeast after hydrating it, waited a week, nothing.
Added enough water to 500g of DME to get it to where I could get it up to 80c, let it cool, poured it in and stirred, and the airlock burst into activity for 2 days.
Left it a while, measured and it's still on 1.030!

So..... question is, has the DME and the subsequent fermentation added a degree of alcohol that is not showing in the FG?
I'm making a loose assumption that if the fermentation finished at 1.030, and I added fermentables to it I would have raised the gravity up a few points by doing that, and the subsequent fermentation has created alcohol until it finished, and I am back to the stop-point at 1.030?
The batch was about 12 litres.

Thoughts?

 

[stevey]

I would guess that you are measuring a fair amount of unfermentable sugars, did you use lactose?
Also high mash temperature will extract unfermentable sugars. Your yeast is obviously good, and has cleared up what it can
To answer your question, yes you have raised the ABV, but that won't do any harm as it was only at 3.54% anyway. You'll just end up with a sweetish stout, which isn't a bad thing imo. I'd leave it a week to settle down then keg it.

 

[Alex.mc]

Yes, it has lactose, so guess the high FG is partly that?
Drinking the samples though it seemed very nice, so not too worried about the final ABV as long as it tastes good.

 

[MmmBeer]

Interesting question, I also regularly get a similar issue. Since I have been using my Grainfather, I always get an OG of 10 - 20 points higher than expected, but rarely get an FG below 1.020.

I made a stout today using Graham Wheeler's Guinness recipe, the book stated an OG 0f 1.041, the Grainfather recipe builder predicted 1.046 and I ended up with 21.5 litres at 1.060, but liquored back to 1.055. The predicted attenuation of the yeast suggests an FG of about 1.012, but I would bet that it wont drop below 1.020.

 

[Alex.mc]

I should say this is my first stout, and first brew with any un-or less fermentable additions, so I'm grasping in the dark somewhat with any new(to me) issues.
I did a Blackberry weiss that took some wierd turns, and ended up low on abv, but nonetheless was fantastic once in the bottle! The efficiency was pretty poor, perhaps 55%, but the beer was still good.
I just did a Sorachi ace recently, again lightly split with a small 4lt batch dry-Rhubarbed! Both it and the main brew came out at 90% efficiency and tasters suggest they are very good!
It's a steep learning curve....... I could be at this for years! :-)

 

[stevey]

I also use the grainfather. I build my recipes on brewmate which has efficiency set at 70%, I always get over 80% efficiency. I know I can change the setting on brewmate, but I'm happy to accept what I get.