[Brewtopalonian]

Hey All!

I recently purchased a Robobrew and have been loving it for its simplicity and the fact that it keeps my garage much cooler in the summer months with the lack of an open flame. I have brewed probably 15 beers on it so far and it works really well.

That said, I've recently brewed 4 beers, all of which have had 100% attenuation which is unbelievable to me. I brewed a double batch of Saison which started at 1.056 and finished at 1.000. I then brewed a cream ale which had an O.G. of 1.048 and finished at .998. I brewed a brown ale which started at 1.052 and finished at 1.009 (intended to be 1.014).

Grist:
Saison -
67.6% Chateau Pils
18.9% Chateau 2 Row
10.8% Flaked Maize
2.7% Special B

Brown -
73.2% Floor Malted Maris
9.8% Crisp Crystal 77L
7.3% White Wheat
4.9% Amber
2.4% Simp Choc
2.4% Gambrinus Honey Malt

Cream Ale -
67.5% Chateau Pils
20% Flaked Maize
10% Barke Vienna
2.5% Briess Cara 10L

Mash temps:
Brown - 156 60mins M/O 170 - 10 mins
Saison - 148 45 mins M/O 170 - 10 mins
Cream - 150 - 60 mins M/O 170 - 10 mins

Yeast Selections:
Brown - Imperial House
Saison - Imperial Napoleon
Cream - Wyeast American Ale II (no starter)

I'm fermenting in FermZilla vessels, but have been for the past year and haven't had this issue. I'm a brewer at a local brewery as well and have asked my co-brewers what their thoughts are and we are all stumped. Figured I'd reach out here to see if anyone can think of something we haven't yet. Thanks!

[Brewtopalonian]

Oh, also, it should be noted that I've not been oxygenating my wort or adding yeast nutrients.

[erockrph]

How do the beers taste? Was there any pellicle or any other signs of infection?  I could see a Saison finishing that low, but not the others. Sounds like either your hydrometer is miscalibrated, or you maybe have an infection in your brewhouse.

[Brewtopalonian]

Beers taste fine, three BJCP judges here and we didn't detect any off flavors. Just puckeringly dry. No pellicle. Gravity taken with two different hydrometers (I was just as confused) and checked with water. Great questions! We had the same.

[ynotbrusum]

Maybe the mash temps were off (on the low side) and you got super fermentable wort?

[Brewtopalonian]

Maybe the mash temps have been off. I'm not 100% on those, but even still... It's hard for me to believe that'd cause 100% attenuation. I suppose it's possible. I'll double check my next one with a probe.

[Bob357]

Have you checked the calibration of your hydrometer and/or refractometer lately. or made some changes in your brewing software equipment profile? If you've eliminated the possibility of an infection, I'd have to guess a measurement or calculation error.

[denny]

Maybe the mash temps were off (on the low side) and you got super fermentable wort?

I dunno if mash temps can be far enough off for that

[Cliffs]

you've confirmed you are measuring correctly, so I think all of this points to infection. Imperial Napoleon is a compulsive diastatic enzyme producer and will attenuate close to 100%. I imagine you have carried over some of that yeast to your other brews.

[jeffy]

you've confirmed you are measuring correctly, so I think all of this points to infection. Imperial Napoleon is a compulsive diastatic enzyme producer and will attenuate close to 100%. I imagine you have carried over some of that yeast to your other brews.

I am not an expert on this, but two of your yeasts are diastaticus and will ferment out completely.  I don't know about the third, but the possibility of cross contamination is good.

[dmtaylor]

As others suggested and I was independently going to say anyway.... sounds like diastaticus contamination from the saison yeast.  Replace all plastic and rubber, including hoses and o-rings, and clean everything really well.

[Brewtopalonian]

Yeah the diastaticus contamination explaination seems most likely. I'll pasteurize everything before next brew.

Though, I didn't think American Ale II was diastaticus.  The cream ale was made prior to the saison. I've made all of these beers before, many times and have never had them come out so dry. I suppose it could be a combination of things.

[Saccharomyces]

My bet is on contamination.

[kramerog]

Diastacus is the most likely explanation, but .... How long does it take for the grain to get up to mash temp? Could it be that there is a long warm up period? I'm just not familiar with the Robobrew.

[Brewtopalonian]

Diastacus is the most likely explanation, but .... How long does it take for the grain to get up to mash temp? Could it be that there is a long warm up period? I'm just not familiar with the Robobrew.

It's almost immediately the way I do it.  I add a little and stir, add more, stir... etc.