Is this beer contaminated?

[Archsnapper]

Three weeks ago I started a Brewdog recipe for Alpha Dog Red Ale which involved a mash at 65°C for 25 minutes and fermenting at 22°C. The recipe called for a California Ale yeast, but HBC sent me Mangrove Jacks M10 workhorse yeast. Anyway, it went mad for two days and then slowed way down only to come alive again about 10 days later. I'm taking hydrometer readings and yes, it's going down daily, beyond the target FG. It's now down at 1.004 and as of today I'm cold crashing it. I'm assuming that until the trub drops out I won't really be able to taste it properly ( ? )

The questions I have are: Has anyone else used M10 Workhorse yeast or is this symptomatic of contamination?

[cruiscinlan]

I used M10 for a barleywine and it got it from 1.12 to 1.020, having been built up as a starter first.  Never had a beer attenuate that low though, but ultimately just draw off a sample and taste it, only way to know really.

[BrewDorg]

You mashed low and used a yeast that is known to attenuate very well. I don't think it has anything to do with a contamination, should be fine.

[Frequent Sequence]

just a sanity check here. Did you boil the wort?
if so: What was your OG?
I would expect a bit less fermentable wort with a short mash.
1.004 seem very low is your hydrometer calibrated?

[Archsnapper]

That's the point - it seems quite mad. Yes, it was boiled, for 1 hour. The OG was 1042 ( target 1046). The hydrometer has appeared to be quite normal over numerous brews. Why on earth has it gone so low?

[Leann ull]

You mashed too low, taste it, is it Ghandis sandal?

[Archsnapper]

I followed Brewdog's recipe which called for that low mash.
I'm letting it clear a bit before the taste test.

[Will_D]

Three weeks ago I started a Brewdog recipe for Alpha Dog Red Ale which involved a mash at 65°C for 25 minutes and fermenting at 22°C. The recipe called for a California Ale yeast, but HBC sent me Mangrove Jacks M10 workhorse yeast. Anyway, it went mad for two days and then slowed way down only to come alive again about 10 days later. I'm taking hydrometer readings and yes, it's going down daily, beyond the target FG. It's now down at 1.004 and as of today I'm cold crashing it. I'm assuming that until the trub drops out I won't really be able to taste it properly ( ? )

The questions I have are: Has anyone else used M10 Workhorse yeast or is this symptomatic of contamination?

I don't understand the OP!

Where is the contamination?

Or do you just have a weird fermentation profile?

[Archsnapper]

Ultimately that's what I'm asking : Has anybody with more experience than me ever experienced such a "weird fermentation profile"?

[Leann ull]

Next question how are you measuring mash temp with, what was temp of strikewater

[Archsnapper]

All done in a Grainfather, so strike water @ 65C but constantly circulating and thermostatically controlled. Mash out  @75C, held for 10 minutes and sparged @ 75 C.

[krockett]

I usually mash at 65 or lower using WLP090 and never got below 1.008 - even using glucose also.

Have read about people finishing that low but it seemed to be a characteristic of the yeast mutating - it happened across batches (was US-05 he was re-using I think)..

[Archsnapper]

Thanks. everybody, for participating. Taste is a little too bitter and there's a slight tang of plastic. I'm dumping it.

[Leann ull]

I'm gutted when folks have to chuck beer especially after 4-5 hours brewing but if it's infected it's the right thing to do.
Now let's help you out.
What's your regime for water as you can get plastic taste from chlorinated water but I think you got an infection.
Please also look at your bucket sanitation or better still throw out that bucket as you may have had a wild infection.
Clean and sanitise the arse out of your gf chilling coil a couple of days before your next brew.
Better luck with the next one.

[nigel_c]

I wouldn't consider 65 too low. A 25 min mash though might be cutting it a bit short.
I'm not 100% on the grainfather setup but do you add the grain and then bring it up to temp or add grains to the 65+ adjusted strike temp? If its the case you bring up to temp you may have spent too long in beta rest area and then went to mash out making a very fermentable wort. Combined with a high attenuating yeast it ripped through it.
Fermenter may have gotten a nudge at day 10 or so and came back to life. To me it doesn't sound infected. Just put it down as one of those things and try learn from it.