Persistently low FG

[dannythemanny]

Hi all,

Bit of a long post here but I'll be very interested to hear people's thoughts...

I took a break from brewing a couple of years ago, but still had your 15kg of pale malt. I kept this sealed and dry. I brewed a beer with it last summer (which I stared another thread about back then) because on racking, I discovered a patchy pink tinge to the bottom of my plastic FV. I ended up chucking the batch because it didn't taste very good and I was a little concerned about whatever caused the bucket to turn pink. I couldn't get it out with Oxy, scrubbing or anything else. Additionally, when I threw it out, I took a hydrometer reading and it was close to zero.

I assumed my beer had fallen victim to a gusher bug somewhere along the line, and chucked out all post-boil plastic that had contacted the beer.

I've just gotten around to brewing again, and was in two minds about whether to use the same malt. I've heard that Fusarium can turn things pink and when it manifests itself in crops it turns them a red/pink colour. However, boiling should surely kill anything that was living on the malt, so how could that be the culprit? Anyway, after a thorough cleaning and sanitising process and using the same malt, I brewed another beer. Went a bit over my target OG of 1.054 and hit 1.058. This was a week ago. It's been fermenting at approx 18C for a week and a gravity reading says it's down to 1.004! Obviously something's gone awry again, but I'm using all new plastic gear and fermenting in glass now.

My question is: What type of infection could this be? Only thing I can think is if the grains do have something nasty on them and I have doughed-in too close to where I've transferred out of the kettle and some dust has lingered in the air for upwards of two hours and made its way into the cooled wort..? Seems unlikely, but unless there's just something in the air, then I can't fathom where this infection is coming from. Other thing is, could it be that something is living on the malt and not being killed in the boil and thus making its way into the fermenter?

A further question I have is this: if an unwanted guest is responsible for fermenting my beer below my target FG (a wild yeast/bacteria), does it necessarily convert the sugar into alcohol, or could it produce some other by products instead? If I brew a beer with an OG of 1.058 and it goes into a never-ending fermentation and gets down to 1.004, is it necessarily 7%ABV?

Final question - if this beer that I currently have 20 litres of tastes ok even with a SG of 1.004, and bearing in mind what I've described above - would you drink it or chuck it?

Thanks for any help.

Dan

 

[foxy]

Drink it, as you mentioned anything that was on the grain would be killed during the boiling process, I had a gusher once caused by using a bottle that had somehow missed out on the cleaning agenda and was filthy. The 20 mm of beer left in the bottom tasted quite good.
Just as a matter of interest was the grain that you had kept for a number of years, was it milled?

 

[Zephyr259]

Yeah, beer's generally safe and tastes bad if something's gone wrong. Out of interest what temperature do you mash at and what yeast have you been using?

 

[dannythemanny]

Thanks for the replies.

Grain was milled by the place I bought it from, yes. Curious as to why you ask... Does storing crushed grain make it more susceptible to having nasties on it?

Mashed at 67C for an hour and checked temp at end. Only dropped 0.5 degree. Yeast was Fermentis US-05.

Cheers.

 

[Zephyr259]

Crushed grain should go stale quicker than whole, probably a matter of months rather than a year or two.

Neither mash temp nor yeast should give that attenuation, I figured you'd known that but worth asking. If you come back saying 63c with a saison yeast then we'd have known why it was finishing so low. :-)

 

[dannythemanny]

Hmm... Having had a read of this I'm feeling fairly confident that the problem is a fusarium infection of the malt. Apparently that can cause gushers through an unknown process, and it would seem boiling doesn't make any difference. I think it's unlikely to actually cause me any harm, but at the same time I'm not sure how much I'll enjoy drinking a beer that I know has "hyperesterogenic effects"!

 

[An Ankoù]

Your malt's fine to use.
What yeast are you using, by the way, to provide such high attenuation?
Are you sure your hydrometer is accurate? Fill your test cylinder with water at the calibration temperature (often 20C) and measure. The hydrometer should give a reading of 1000.

It would be interesting to see your recipe.

 

[dannythemanny]

Fermentis US-05

5kg Maris Otter
Mash at 67 for one hour

30g Amarillo 60 min
50g Amarillo 5 min
20g Amarillo flame out

 

[An Ankoù]

Looks about right. My most recent bag of MO was giving me just over 1050 for 5Kg in 23 litres, while I'd expect 1055++ with other pales. With US-05 I'd expect an FV of 1006 or 1007, but I mash a couple of degrees lower lower than you.
I reckon you've got to check your hydrometer as I suggested above. No way you can get down to 1004 with US-04without using additional enzymes.
Just thought of something. Are you reading from the top of the meniscus or the bottom? My hydrometer would read 1004 at the top of the meniscus and 1006 at the bottom.
I'm sure you know this but the meniscus is where the surface tension of the liquid causes it to climb up the hydrometer a few millimetres. You've got to take the reading at the level of the flat surface of the liquid. (Unless you hydrometer explicitly states you should read at the top).

 

[dannythemanny]

I'm actually using a Tilt hydrometer - a really fancy one that connects to your phone to give you real time readings. It's the first time I've used it, but I calibrated it first and it seems fine. Tomorrow I will draw off a sample and use my regular hydrometer to test it, but I'm fairly confident the Tilt is accurate. I just think it's a gusher bug brought about by Fusarium on the grain. I'll let you know what the other hydro says tomorrow.

 

[An Ankoù]

I'm actually using a Tilt hydrometer - a really fancy one that connects to your phone to give you real time readings. It's the first time I've used it, but I calibrated it first and it seems fine. Tomorrow I will draw off a sample and use my regular hydrometer to test it, but I'm fairly confident the Tilt is accurate. I just think it's a gusher bug brought about by Fusarium on the grain. I'll let you know what the other hydro says tomorrow.

Ok, but I don't see how any infection in the grain would survive a 60 minute boil. Even anthrax wouldn't survive a 60 minute boil.

 

[dannythemanny]

I don't either, but this article is pretty interesting.

I'm not a scientist, but could it be saying that the fungus itself doesn't survive, however some of the toxins produced by it on the grain beforehand does and that somehow causes over-fermentation and gushing?

 

[Spratt]

I'm actually using a Tilt hydrometer - a really fancy one that connects to your phone to give you real time readings. It's the first time I've used it, but I calibrated it first and it seems fine. Tomorrow I will draw off a sample and use my regular hydrometer to test it, but I'm fairly confident the Tilt is accurate. I just think it's a gusher bug brought about by Fusarium on the grain. I'll let you know what the other hydro says tomorrow.

I'm not sure I share your confidence in the Tilt. I've been using one for a couple of years now and though the initial S.G. is usually within a little (say a couple of points) of the hydrometer reading, my F.G. is usually at least 10 points adrift (it was showing 1.001 on my last brew whereas the hydrometer was showing 1.015 - this was a strong beer, and the usual difference is nearer 10 to 12 points). I keep using it, as I believe its temperature function is more accurate, and that gives a pretty good indication of the relative progress of the fermentation, but as to its gravity readings, I take them with a pinch of salt.

There's quite a lot of discussion on the web about the accuracy of Tilts, with some people concluding that as the fermentation progresses, the rubbish that collects on the cap of the Tilt distorts its ability to float properly and hence give a true reading. I have seen suggestions that they should produce it with a conical cap so that there was more chance of the top keeping clean.

Having said all that I believe they did update it in 2018, so it may be that my older version is less accurate.

 

[kelper]

Not thinking particularly of mashing but remember, that if an infection of food sets in, the killing of the bacteria does not remove any toxins they may have produced. This is why irradiated food and chlorine-washed chicken are such bad ideas. Think of botulism and ricin! (Ricin is denatured by boiling; Botulism spores are NOT inactivated by boiling)

 

[dannythemanny]

Good news..! Sort of... I had a little taste and thought it was very, very good. So I drew off a sample for a gravity reading with my normal hydrometer, and it came out at 1.014. Spot on! So, in my hiatus from home brewing, I must have forgotten rule #1: RDWHAHB.

Bit disappointed that the Tilt gave such a poor reading... That would make sense about it accumulating gunk on it during fermentation and being weighed down, particularly since a lot of trub made it into the fermenter on this occasion. Although I did notice in the middle of fermentation that it gave one reading that was low by exactly 10 points before suddenly jumping ten points back up to where it was, so I wonder if it could be a software issue..? Or more likely just a coincidence. Shame because as you know, they're not cheap and it's a great idea. Like you say, it's still very handy for monitoring temp anyway.

Glad I didn't chuck the rest of that malt yet!

Thanks again, guys.

Dan

 

[Spratt]

Good news..! Sort of... I had a little taste and thought it was very, very good. So I drew off a sample for a gravity reading with my normal hydrometer, and it came out at 1.014. Spot on! So, in my hiatus from home brewing, I must have forgotten rule #1: RDWHAHB.

Bit disappointed that the Tilt gave such a poor reading... That would make sense about it accumulating gunk on it during fermentation and being weighed down, particularly since a lot of trub made it into the fermenter on this occasion. Although I did notice in the middle of fermentation that it gave one reading that was low by exactly 10 points before suddenly jumping ten points back up to where it was, so I wonder if it could be a software issue..? Or more likely just a coincidence. Shame because as you know, they're not cheap and it's a great idea. Like you say, it's still very handy for monitoring temp anyway.

Glad I didn't chuck the rest of that malt yet!

Thanks again, guys.

Dan

Yes, I've found it oscillates quite a bit sometimes before the reading becomes relatively stable. I think if you're uploading the data to the cloud, you can get a reasonable average because there are so many readings, but I've always just used the readings straight off my phone. It is frustrating that the Tilt is not perfect, because it's such a good idea in theory, but even with its limitations I still find it very handy. I have a brew fridge where I can draw off a sample from the tap, so I use the hydrometer there, but I sometimes also use an old cattle trough heated by an aquarium heater, and the Tilt is really helpful then, for letting me know when fermentation has finished without having to take the lid off and sample from the . Glad the brew is good anyway, that's the most important thing. David

 

[An Ankoù]

I hadn't heard of Tilt until this thread. I'll stick with my trusty hydrometer, thanks. I can't imagine why you'd want any extraneous equipment hanging about in your beer during fermentation anyway.

 

[kelper]

I hadn't heard of Tilt until this thread. I'll stick with my trusty hydrometer, thanks. I can't imagine why you'd want any extraneous equipment hanging about in your beer during fermentation anyway.

Tilt 2 is fantastic. You can watch your fermentation remotely without disturbing it. Mine seems spot on for accuracy after the initial yeast burst and it clearly shows when fermentation has paused or finished. No need to expose your precious brew to air and pathogens. Mine had a good crust of dried krausen on it at the end of fermentation so I cleaned it and put it back. The reading changed by one point. I left the brew in the FV and it took several days to drop the last point,so, I might have transferred it early if taking manual SG readings. Plus, I love gadgets! I can monitor SG and temp even away from home.

 

[dannythemanny]

It is great being to get gravity readings without disturbing the beer. I wonder if I'm having this problem because it's in a carboy... Maybe it got stuck on the shoulder and that's thrown up an erroneous reading. I will definitely use it again and maybe try it in a bucket next time.

 

[kelper]

It is great being to get gravity readings without disturbing the beer. I wonder if I'm having this problem because it's in a carboy... Maybe it got stuck on the shoulder and that's thrown up an erroneous reading. I will definitely use it again and maybe try it in a bucket next time.

Or fill the carboy less?