4th BAIB, still missing my SG's!

[nacnud]

Hi Guys,

I've done 4 BIAB's now and I've had the same problem every time. I always end up with a FG well below my target and as a result my beers, though perfectly drinkable, are turning out stronger, thinner and more bitter than I had intended. I just Can't figure out what I'm doing wrong.

For my latest (A take on the Dr Smurto's Golden Ale) I used:

1.2kg JW Trad Ale
0.4Kg Munich 1
0.4Kg Wheat
0.15Kg Caramunich 1

For 10L into fermenter

Strike Temp 71 degrees. Mashed at 68 for 60 mins then mash out to 78 degrees. Dunk sparged in 2L 78 degree water.

60 min boil with 5g Centennial @ 60 mins, 10g Amarillo @ 20 mins and 5g Amarillo @ 5 mins.

Yeast: us-05 @ about 18 - 20 degrees for primary.

OG was 1.039 (target 1.041 @ 65% efficiency). Target FG was 1.011 and after 4 days in primary it's at 1.009!

My Efficiency has always been rubbish and this is the first time I've done a mash out but it didn't seem to help. I also raised the mash temp a little to try to get a higher FG but it doesn't seem to have worked. I'm out of ideas...

Any suggestions welcome.

 

[tiprya]

How is your grain crushed?

Higher mash temp wont increase gravity (unless you're not getting full conversion - but 60 mins at 68 will be fine)

 

[slash22000]

1.039 -> 1.009 is ~77% attenuation, pretty normal for US-05. I'm not sure why you think it would stop at 1.011, that would be ~72% attenuation which would be quite low for US-05.

Are you specifically aiming for a low alcohol beer? Or is that just a result of your efficiency?

 

[sp0rk]

go a finer crush
I was hitting below 70% with the grain just cracked, now I'm getting mid 80s by crushing to flour (also BIAB)

 

[nacnud]

For the last three I've been crushing my own grain using a modified pasta roller. It seems a pretty good crush to me but I wouldn't really know. The first one I did I ordered from grape and grain and had them crush it for me. I think what I'm producing is similar.

Shouldn't a higher mash temp produce more unfermentable sugars and therefore a higher FG?

Slash, What I would like is a beer with more body. The one's I'm coming up with are too thin for my taste.

 

[Phillo]

I usually mash for 90 mins and consistently get around 72% efficiency. Just for the hell of it I tried a 60 min one last time and got 67%. :angry:

Maybe try 90 next time?

Also, the finer crush was what got me into the 70s in the first place.

 

[mxd]

I assume your talking about the gravity post fermentation not post mash/boil or do you mean both.

 

[Bribie G]

Seems odd that you are mashing quite high but getting low FG - I'm actually just hangin' a bag right now after mashing at 68 to produce a big bodied more malty beer (a London ESB) and hoping for a FG of 1016 or something like that.

I'd be looking at your thermometer and suggest popping out to Big W or Target and getting a nine buck probe digital thermometer. They work quite well and I find them accurate within a degree, and compare readings with your current therm.. as well as doing the ice water and boiling water test as well.

 

[GuyQLD]

Missing a few key points in your original post to actually troubleshoot.

Pre Boil Gravity - Without this you have no idea of your conversion efficiency. Since every other measurement of efficiency beyond this point is a factor of this initial measurement without it we don't know where to start.

Once we establish what your conversion efficiency is we can start troubleshooting your process. If you're getting poor conversion you would look at;

1. Crush
2. Temperature + time (90 mins mash and a mash out. I suppose you could include your dunk sparge here)

There's a number of other things such as water profile and the malt bill which might affect but are probably of low importance at this point.

Once we establish that your conversion efficiency is OK then we can look into what factors in your process might be hampering on your ability to translate those extracted sugars into finished product. Trub loss is the biggest killer out there as it's a straight off the top measurement. Boil off can also play a big part. Too much and you're going to leave more concentrated wort behind with your trub. Too little and you're getting weaker wort to start with.

There's a lot of things you can try but my advice is to focus on one thing at a time and start with conversion efficiency. You can have the best practice in the world post boil but it's not worth a jot if you can't get decent conversion up front.

 

[nacnud]

I have my pre-boil SG written down as 1.035 before adding sparge water. I didn't write down the volume... still learning.

I've currently got my thermometer in a pot of boiling water reading 103.5, hmmm... If that is the issue I'll bit a bit pissed and more than a bit relieved. Ice water test to follow.

I suppose a finer crush can't hurt with BIAB, right? Or can you get a wheaty taste from the husks? Will give that a go next time as well as a 90 min mash.

 

[GuyQLD]

Adding the sparge water probably diluted it, assuming that the sparge OG was not as high as the original OG. Next time take the gravity right before you start ramping it up to the boil. Preferably a room temp sample would be better. I don't trust those temperature conversion calculators.

Also a new thermometer is a must. Bribie is spot on there. 3.5'C is significant when you're looking at fermentability profile of a single infusion.

Lets say you really mashed at 65'C - it's going to be more fermentable (less bodied) than you were expecting at 68'C

 

[nacnud]

OK, Thanks guys. I'll get my hands on a new thermometer and try again this weekend. Will report back.

 

[Big Macca]

I third the comment on temperature. I had one of those weldless thermometers and worked out after a few lighter and thinner than expected brews that there was up to a 4 degree difference if I viewed at any angle other than straight in front. This took me from 65->75 and more body.

I've had improvemed efficiency with regular stirring up of the grain bed during BIAB mashing. I don't mean just stirring it like a pot of soup, I mean really getting under the grain and lifting up to stop clumping. This also ensures even water temp from the bottom to the top of the mash tun. This took me from 75->85.

A fine crush works well for BIAB, I find that the husks are still intact, just have more flour in the grist. I've read in forums that you only have problems with a grind affecting the flavour if you use a grinder that has a cutting action like blender.

Good luck!!

 

[CosmicBertie]

Hmmm....I'd also be inclined to say temperature. 3 degrees out would make it more fermentable.

However, you're talking about .002 out. Its hardly way off target, I'd be happy at that if the beer tasted ok. Differences in malt kilning can attribute to estimate gravities being out, so too if you've chosen a slightly different malt in your brewing software.

You do right to experiment to improve, but if only after 4 brews you're damn close, then you're doing well

But you've tested the thermometer and found it to be out....replace it.