Final alcohol percentage higher than official tolerance?

[GillesF]

Hi all

I brewed a Belgian Quad last Saturday and accidentally used the Mangrove Jack's M47 yeast instead of the M41. This yeast has an official alcohol tolerance of 8% while my recipe is 9.5% alcohol. I was thinking of ordering US-05 to finish the last 1.5% but apparently the yeast has already finished 4 days later and ended up at 9.2% alcohol. Is it normal to go so high above the tolerance? Or did I infect it with a wild yeast?

Here's the grist bill:

3.738 kg (72%) — Dingemans Pilsen MD — Grain — 3.2 EBC
363 g (7%) — Weyermann Caramunich I — Grain — 101 EBC
259 g (5%) — Corn, Flaked — Grain — 2.6 EBC
52 g (1%) — Weyermann Carafa I — Grain — 630 EBC (added during last 15 minutes of mash)

416 g (8%) — Candi Syrup Candi Syrup, D-180 — Sugar — 355 EBC
363 g (7%) — Candi Sugar, Clear — Sugar — 1 EBC

Mashed at 60 - 61° (141 - 142F) for 60 minutes.

Thanks all!

Gilles

 

[hottpeper13]

I would expect this outcome with 20% sugar and the low mash temp.

 

[odie]

pretty sure those tolerances are not written in stone and likely on the low side.

it would look pretty bad if their yeasts under perform. kinda like expiration dates...conservative.