stuck at 1.015

[fluketamer]

i brewed a lager last weds and my efficiency wasnt great . the munich light i added was crushed way to fine like flour and it clumped in the mash. i think thats why my efficiency was low. i also had a ton of trub left in the kettle. all went well except it got stuck at 1.015. i warmed it up 2 degrees and got it down to 1.014 but i think its done. it looks like only about 70 percent attenuation with 34/70. previously i have done better like high 80 with 34/70.
it comes to around 4.18 abv. i was hoping for much closer to 5.

1) i swirled it and warmed it. anything else i can do to dry this out a little more or is it too late.?


2) is it possible the flour left behind unfermentable sugars that raised my initial gravity but are now the reason for the high FG? maybe theres no more sugar for the yeast to eat? i thought its too late for nutrients, is it too late for enzyme or is that not the issue?

i am going to let it go another week in primary but doubt it will drop the gravity anymore.

thanks for any replies

 

[lumpher]

You can add Amylase Enzyme to it, but that's hard to control and may make it too dry. You could add yeast energizer, but probably won't help. I think you're on the right path with the crush being like flour. I'd just let it go and treat like normal.

 

[doug293cz]

You can add Amylase Enzyme to it, but that's hard to control and may make it too dry. You could add yeast energizer, but probably won't help. I think you're on the right path with the crush being like flour. I'd just let it go and treat like normal.

Alpha amylase is self limiting, as it cannot convert small (limit) dextrins to fermentable sugar. It does however convert portions of large (non-limit) dextrins to limit dextrins and fermentable sugar. Glucoamylase (aka amyloglucosidase, or just gluco) will convert all dextrins to fermentable sugar, and can really thin out a beer - think FG 1.000, or lower.

If you got the flour well mixed in with the rest of the mash, it should have converted faster than the coarser grits. If however, the flour was clumped into dough balls during the mash, then only the outside of the dough balls would have converted.

Which efficiency did you measure? Conversion efficiency will tell you how much of the starch got converted to sugar. Mash efficiency is equal to conversion efficiency times lauter efficiency, so if you know mash efficiency and conversion efficiency, you can calculate lauter efficiency.

It's possible that the larger than normal amount of flour could have hindered lautering, due to higher flow resistance in the grain bed. But you would need to have taken the data necessary to calculate conversion efficiency to know your lauter efficiency, and which one led to lower "efficiency" (which ever one you are discussing.)

Brew on