Significant over attenuation!

[DarrenSL]

My latest brew has finished fermenting at 1.003! OG was 1.061, a 95% attentuation.

The recipe was 5.45kg Extra Pale + 0.45kg Pale Crystal with BRY-97 yeast. I got distracted during the mash and ended up mashing for 90 minutes at 66C. My sparging isn't great either. I always struggle to get the grain bed up to mash out temperatures (because I sparge too slow I think) so I that would have added at least another half hour at active enzyme temperatures.

So, given the low temperature and extra long mash time, is a 95% attenuation possible with an all malt bill or is something else going on?! Although infection is always a possibility, it seems unlikely given that I brew in all stainless steel which is always fully stripped down and scrubbed. I also bake all silicone and small parts in the oven for 30 minutes.


Thanks

 

[Sadfield]

Given you've 7.5% Crystal in the grist I'd wouldn't expect to go that low, for a long 66°C mash. Some brewers overnight mash without seeing such results. It's the super-attenuation I'd expect from a Saison type yeast.
High attenuation for BRY-97 would be in the mid 80's.

 

[MashBag]

I wouldn't rule out infection just 'cos it's stainless. The beasties can't tell the difference

 

[DarrenSL]

I wouldn't rule out infection just 'cos it's stainless. The beasties can't tell the difference

Thanks. I'm just referring to the fact that its easier to clean and less likely to scratch than plastics. But, it is looking likely that there might be a wild yeast infection in there somewhere! Although I have no idea how I can sanitise further than I already do.

 

[Agentgonzo]

95% seems really high, even for a low/long mash. I expect a wild yeast could be the culprit. Have you brewed with a diastaticus strain recently (saison)?

Although I have no idea how I can sanitise further than I already do.

My usual regime of scrubbing and starsan won't necessarily kill any residual diastaticus yeast, so after brewing a saison I steam-treat my fermenter. Steam will get it up to ~100C which will kill any yeast. Stainless steel is good for this because the heat won't affect the fermenter and it conducts the heat really well into all the hard-to-get to regions. I just invert it on top of a boiling pot on the stove for 15 minutes.
https://www.thehomebrewforum.co.uk/threads/cleaning-fermenter-after-infection.101822/post-1212383

 

[borischarlton]

Thanks. I'm just referring to the fact that its easier to clean and less likely to scratch than plastics. But, it is looking likely that there might be a wild yeast infection in there somewhere! Although I have no idea how I can sanitise further than I already do.

Have you taken the valve apart? Removed the lid seal? As already suggested, Diastaticus I would think is most likely.

 

[DarrenSL]

I just invert it on top of a boiling pot on the stove for 15 minutes.

Thanks for that tip. I use the same fermenter so will try that. I've always had concern that the tap may harbour something because it cant be dismantled (and I've seen the sort of gunk that builds up behind the ball when I strip down my 3 piece taps). I usually put the tap in the oven (after removing the plastic handle).

I've never brewed a saison but I have brewed many lagers. It's worth noting that I've never had a bad or over attenuated lager in 10 years+ of brewing but I have had this same problem a number of times when brewing pale ales and IPAs. It's really odd!

 

[DarrenSL]

Have you taken the valve apart? Removed the lid seal? As already suggested, Diastaticus I would think is most likely.

Thanks. Posted my reply above as you posted this. The lid seal is also a potential concern even though I bake that and have put it through the dishwasher a few times. I have noticed that the seal doesn't smell great after fermentation. Has a very strong phenolic smell although this isnt present in the beer.

 

[Sadfield]

Two useful snippets.

1) From another website regarding Brettanomyces. Applicable to any "Wild" yeast.

2) The second, a reply to me asking Lallemand what they recommended for their diastatic Belle Saison yeast.

 

[Sadfield]

I've never brewed a saison but I have brewed many lagers. It's worth noting that I've never had a bad or over attenuated lager in 10 years+ of brewing but I have had this same problem a number of times when brewing pale ales and IPAs. It's really odd!

That would suggest there's something that prefers warmer temperatures such as lactic acid bacteria.

 

[Clarence]

My latest brew has finished fermenting at 1.003! OG was 1.061, a 95% attentuation.

The recipe was 5.45kg Extra Pale + 0.45kg Pale Crystal with BRY-97 yeast. I got distracted during the mash and ended up mashing for 90 minutes at 66C. My sparging isn't great either. I always struggle to get the grain bed up to mash out temperatures (because I sparge too slow I think) so I that would have added at least another half hour at active enzyme temperatures.

So, given the low temperature and extra long mash time, is a 95% attenuation possible with an all malt bill or is something else going on?! Although infection is always a possibility, it seems unlikely given that I brew in all stainless steel which is always fully stripped down and scrubbed. I also bake all silicone and small parts in the oven for 30 minutes.


Thanks

I shouldn't start worrying about infections and contamination if I were you. And your cleaning regime looks spot on.
I rarely, if ever, get the FV predicted by a recipe and it can end up anywhere between 1003 and 1008 regardless of yeast variety unless it's one of those that don't ferment maltotriose. I know I haven't got a diastaticus or any other infection because I get the same results using brand new equipment. In any case, low FG suits me as I don't like to bottle higher FG beers.
I suggest that the low FG is entirely down to your mashing regime. You're mashing around 66C and falling. Your thermometer only needs to be a degree out for that to be 65 and falling. You're effectively mashing for at least a couple of hours, probably more by the time you've heated the wort and that's plenty of time for the wort to become very fermentable. If you want a high FG, you need to mash a bit higher, stopping when the starch end point is reached and then you need to raise the whole mash, quickly, to the mash-out temperature, it's not enough just to raise your sparge water to that temperature and then start slowly sparging. My mash and sparge regime is very similar to what you describe. I often mash overnight and so I don't bother "mashing out" so it's not surprising I get similar results.
My advice would be to continue to clean thoroughly and then trust your cleaning and concentrate on getting your mash and sparge to where you want it. I'm happy to get the results you're getting now: I don't like sweet beer and I've never thought my beer lacked body.

Consider this. If you clean decently but you leave a couple of cells of diastaticus or any other unwanted bug in there, how long is it going to take them to build up to a viable colony, especially in the face of the massive competition from the yeast you've pitched? If they're going to take hold it's not going to be within the relatively few days of visible fermentation after which you record your FG. If they take hold at all it's going to be in the weeks and months after you've packaged, possibly causing bottle bombs, but not likely as the beer is already very well attenuated.

 

[Sadfield]

The problem with diastatic yeasts @Clarence is they excrete glucoamylase enzymes that reduce dextrins into simpler sugars that the pitched yeast can also consume. A little can go a long way. And it's not just yeast that can work in tandem like this.

https://onlinelibrary.wiley.com/doi/10.1002/j.2050-0416.1952.tb02675.x
The OP only mashed 30 minutes longer.

 

[Clarence]

The problem with diastatic yeasts @Clarence is they excrete glucoamylase enzymes that reduce dextrins into simpler sugars that the pitched yeast can also consume. A little can go a long way. And it's not just yeast that can work in tandem like this.

https://onlinelibrary.wiley.com/doi/10.1002/j.2050-0416.1952.tb02675.x

Yes I know. And I heard they can also protect themselves in cracks and scratches by creating a biofilm. But I still wonder how many, if any will remain viable after the thorough clean the OP has claimed, and whether they could establish themselves in time to affect the FV reading. Especially when it's clear that the OP's mash and sparge regime is going to give a more fermentable wort than otherwise.
There is a test, of course, and that is to do a brew, with a 60 minute mash time at 69-70C and ferment it with Windsor and see what happens then. If there's a containation, the FV won't just be lower than expected, it'll end up very low.
That looks an interesting article, I give it a read.

 

[DarrenSL]

Thanks everyone. Interesting discussion and I'm glad I asked the question! I've been racking my brains over this because I had the same view as Clarence in that how can such a small number of microbes cause so much attenuation in just 2 weeks. And at the same time, thinking how can a 90 minute - 3 hour mash do this.

I guess I'll just have to tackle it from both sides. Batch sparge to immediately stop conversion at the 60 minute point (after starch test) and also replace all silicone tubing/seals and steam sanitise everything else!

 

[borischarlton]

@Clarence The problem is the beer has not turn out as the brewer wanted. It is almost certainly caused by some sort of contamination.

@DarrenSL Not sure if your fermenter is the same or similar to the one we sell however, the valve should completely disassemble using a 12mm hex bolt

 

[Sadfield]

Mash time is easily rectified.

I brew in all stainless steel which is always fully stripped down and scrubbed. I also bake all silicone and small parts in the oven for 30 minutes.

What happens after baking? What cleaners and sanitisers are you using after reassembly?

Are you pitching dry yeast straight from the packet? Or, does your yeast handling involve anything more? How much yeast for your batch size?

 

[The Baron]

I think it could be many of the discussed factors but I certainly would not do slow sparges in my world as my time is too precious and it will carry on extracting sugars unless you do a mash out so that could be part of the issue as it is making the wort efficiency very high compared to a 60 minute then mash out.
I prefer to get 75% average eff and then lock it with a mash out

 

[DarrenSL]

@Clarence The problem is the beer has not turn out as the brewer wanted. It is almost certainly caused by some sort of contamination.

@DarrenSL Not sure if your fermenter is the same or similar to the one we sell however, the valve should completely disassemble using a 12mm hex bolt

It's an SS Brew Bucket (without the yeast dumping valve). The tap is very small and doesn't have a hex bolt. I've tried to remove the teflon ring but it wont budge. As you can see, there is some discolouration of the teflon which doesnt give me confidence that it is entirely sanitary which is why I bake it before each brew. I would love to replace the part with something better but have not been able to find anything of this size.

 

[DarrenSL]

Mash time is easily rectified.



What happens after baking? What cleaners and sanitisers are you using after reassembly?

Are you pitching dry yeast straight from the packet? Or, does your yeast handling involve anything more? How much yeast for your batch size?

Just a star-san rinse after baking. For general cleaning I scrub using a new sponge with soapy water and rinse well followed by starsan rinse or spray. And for anything that I cant get to e.g. kegs, bottles, i use percarbonate.

For this brew, I used dried yeast which I hydrated in cooled boiled water.

 

[Sadfield]

I'd use the percarbonate on the FV, too.

I don't think you can go too far wrong with...

1) Physical clean to remove the bulk of soiling.
2) Alkaline cleaner.
3) Rinse.
3) Acid based no rinse sanitiser.

Concentration + Temperature + Contact time.

Steaming like @Agentgonzo suggests is good for sanitising, too.