Bloody Fermentation!

[kieran]

The last 3 brews that I've done have all ended up undercooked, and I can't tell why.

OG's are in the 1050-1060 range, quite normal.. all taste on the money pre-ferment.
Using Safale Fermentis yeasts, the first two were pre-started with wort for a 4-5 hours to partially activate the yeast before pitching properly.
The last one was sprinked in while aerating.

I bubble away with an aeration stone for a good 20 minutes after chilling post-boil. I pitch the yeast at about 18C (all 3 were ales).
Fermentation kicks along at 18C for a week, then things slow down. I ferment in a fridgemate-controlled chest freezer.

The previous two made it to 1020.. the american pale ale I did 7 days ago is at 1022 now (OG 1051). I'm using Safale US05 this week.
It's been a cool week, so I'm going to rack it in a day or so, and see how it goes after another week.

However, after brewing for 5 years, I've never had this happen previously. I'm scratching my head. Usually my fermentations are all done within a week to 10 days (for ales).
There shouldn't be many unfermentable sugars in there, the mash was done at 68C.. so not overly warm, so there should've been a good degree of conversion to fermentable sugars. Similar profile really to the last two brews.

After never having this problem, as it's just a bloody simple thing, I can't quite grasp what it might be. Maybe the fridgemate calibration is borked and it's too cold.. hmm.

any ideas?

 

[DJR]

Take it out of the fridge, give it a gentle swirl. Maybe it's just cold.

Most of the flavours from fermenting too high (esters etc) come in the first 48-72 hours of ferment, ie. the lag phase and start of the attenuation phase, so no harm in letting it get warm after the first few days.

 

[kieran]

Take it out of the fridge, give it a gentle swirl. Maybe it's just cold.

Most of the flavours from fermenting too high (esters etc) come in the first 48-72 hours of ferment, ie. the lag phase and start of the attenuation phase, so no harm in letting it get warm after the first few days.

Cheers, worth a shot. I can't quite fathom why its happening now though..

 

[malt_shovel]

The last 3 brews that I've done have all ended up undercooked, and I can't tell why.

OG's are in the 1050-1060 range, quite normal.. all taste on the money pre-ferment.
Using Safale Fermentis yeasts, the first two were pre-started with wort for a 4-5 hours to partially activate the yeast before pitching properly.
The last one was sprinked in while aerating.

I bubble away with an aeration stone for a good 20 minutes after chilling post-boil. I pitch the yeast at about 18C (all 3 were ales).
Fermentation kicks along at 18C for a week, then things slow down. I ferment in a fridgemate-controlled chest freezer.

The previous two made it to 1020.. the american pale ale I did 7 days ago is at 1022 now (OG 1051). I'm using Safale US05 this week.
It's been a cool week, so I'm going to rack it in a day or so, and see how it goes after another week.

However, after brewing for 5 years, I've never had this happen previously. I'm scratching my head. Usually my fermentations are all done within a week to 10 days (for ales).
There shouldn't be many unfermentable sugars in there, the mash was done at 68C.. so not overly warm, so there should've been a good degree of conversion to fermentable sugars. Similar profile really to the last two brews.

After never having this problem, as it's just a bloody simple thing, I can't quite grasp what it might be. Maybe the fridgemate calibration is borked and it's too cold.. hmm.

any ideas?

Get a spirit thermometer and check you mashing temp and ferment temp. That's cheap and easy.

The more remote chance maybe a dodgey batch of yeast (badly handled before you got it), so change your yeast supply.

 

[Mitcho89]

Real shame mate. I've been brewing for about 18 months mainly with just kits.....and I sometimes get that from time to time. Winter plays hell on us brewers..

 

[rich_lamb]

Might want to try checking the calibration of all your measurements - if your mash thermometer was 'suddenly' out by a couple of degrees it would explain it, probebly less likely to be your ferment temp but worth checking. Test the hydrometer also.

My 2c those airstones are a waste of time and hard to sanitise completely - a good thrashing works well (good for the wort too!). But either way, you should be getting enough oxygen in there. And if you're pitching dry yeast you should have no concerns about viability - unless it's really OLD dry yeast.

 

[hbnath]

You have to admit that there has been a rather large number of people posting the same thing (or at least commenting on posts and agreeing) that you would have to wonder if there was some sort of batch problem with some of the yeasts lately. This was suggested in one of the last posts too.

I did my very first all grain, and I know that being a newb I am open to all sorts of variables...but having hit the marker on most of the measurements I also had a problem getting my FG down using US-05. No matter what I did it just wouldn't go past 1020 having started at 1052. Anyway...I just bottled it in PETS and it seems to be behaving

 

[jamiefbacon]

You have to admit that there has been a rather large number of people posting the same thing (or at least commenting on posts and agreeing) that you would have to wonder if there was some sort of batch problem with some of the yeasts lately. This was suggested in one of the last posts too.

I did my very first all grain, and I know that being a newb I am open to all sorts of variables...but having hit the marker on most of the measurements I also had a problem getting my FG down using US-05. No matter what I did it just wouldn't go past 1020 having started at 1052. Anyway...I just bottled it in PETS and it seems to be behaving

I'm starting to think the same thing I'm having same problem with us05 and when I've used liquid yeast haven't had the problem maybe there is a dodge batch getting around

 

[MHB]

This sort of problem makes a fairly regular appearance around here, the first port of call is usually to blame the yeast and if memory serves that turns out to be the least likely culprit.
Breaking the problem down into the two most likely causes
1/ the wort isnt as fermentable as you would like it to be, this is basically going to be the mash temperature, you need to (as several have commented) calibrate your mash thermometer.
2/ the yeast isnt attenuating, there are two likely answers to this one.
a/ a faulty batch of yeast, this can happen but its vanishingly rare. The quick way to test for this is to run a sample of your beer into a jar and add a whole packet of cheap dry yeast (like from under a kit lid) leave the sample somewhere warm for a day or two and check whether the gravity has moved, if not see 1/ if so, the yeast may be at fault or...
b/ your fermentation temperature isnt what you think, fridges have a strong tendency to form thermal layers, if your probe was half way up the fridge and it was reading 18oC it can easily be several degrees colder at the bottom of the fridge, in fact cold enough to send the yeast dormant. A cheap fan in the fridge will fix this problem, and improve the temperature control of the fermentation. Getting a good accurate measurement of the actual temperature in the fridge would be a given, you can never trust digital readouts.

There are a couple of other possible contributors; aging or slack malt can throw up some funny results, really bad water chemistry, some form of contamination to name a few.

I might be stirring up a hornets nest but to my mind there is no benefit to aerating a wort if you are pitching the right amount of dry yeast. My last brew with US-05 dropped from 1.086 to 1.016 in 10 days. That was 4 packets of US-05 without aerating or rehydrating making for a pitch rate of about a million cells / point of Plato / mL of wort.
Lets not start the rehydration war again, I know conventional wisdom on AHB is in favour, and so am I provided it is done properly which it rarely is. Unless you pay very particular attention to the hydration process you can do more harm than good.
MHB

 

[Nick JD]

Mashing at 68C and finishing at 1.020 is par for the course.

68C is "overly warm".

Try one at 62C and see where your FG lands.

 

[kieran]

Mashing at 68C and finishing at 1.020 is par for the course.

68C is "overly warm".

Try one at 62C and see where your FG lands.

You think?
I do Scottish 80/-'s at 70C.

I don't think its my mash thermometer..

The thermometer in the kettle read 75C, after mashing in on a cold morning the mash tun read 69C.. which droped by 2.5-3C over the mash schedule to 66C. This is spot on as calculated for the thermal mass and heat transfer coefficients for my mash tun as calculated by BeerTools Pro.
So to have *two* thermometers out by the same amount, while not impossible, is rather improbable: and everything else temp-wise seemed to work out.

I followed a recipe in John Palmer and Jamil Zainashef's Brewing Classic Styles..
The American Pale ale OG at 1051 was on the money.. and mash temp at 68C was about right too.

The only thing that isn't playing out is the FG (so far!). I'll check the wort in a couple of days, and if it hasn't shifted.. I might pitch some more yeast.

 

[Deebo]

You have to admit that there has been a rather large number of people posting the same thing (or at least commenting on posts and agreeing) that you would have to wonder if there was some sort of batch problem with some of the yeasts lately. This was suggested in one of the last posts too.

I did my very first all grain, and I know that being a newb I am open to all sorts of variables...but having hit the marker on most of the measurements I also had a problem getting my FG down using US-05. No matter what I did it just wouldn't go past 1020 having started at 1052. Anyway...I just bottled it in PETS and it seems to be behaving

People dont really post when everything goes fine. I have just used a batch of us-05 in fermenting fridge at 17c and it got down to 1010 with no problems.
If it was 1020 and the yeast was the problem you would either get no carbonation or exploding bottles I would think?

 

[seemax]

Lets not start the rehydration war again, I know conventional wisdom on AHB is in favour, and so am I provided it is done properly which it rarely is. Unless you pay very particular attention to the hydration process you can do more harm than good.
MHB

The instructions given on the Danstar packets are pretty straight forward... what makes you think it's rarely done properly?

 

[seemax]

Lets not start the rehydration war again, I know conventional wisdom on AHB is in favour, and so am I provided it is done properly which it rarely is. Unless you pay very particular attention to the hydration process you can do more harm than good.
MHB

The instructions given on the Danstar packets are pretty straight forward... what makes you think it's rarely done properly?

 

[Ross]

You think?
I do Scottish 80/-'s at 70C.

I don't think its my mash thermometer..

The thermometer in the kettle read 75C, after mashing in on a cold morning the mash tun read 69C.. which droped by 2.5-3C over the mash schedule to 66C. This is spot on as calculated for the thermal mass and heat transfer coefficients for my mash tun as calculated by BeerTools Pro.
So to have *two* thermometers out by the same amount, while not impossible, is rather improbable: and everything else temp-wise seemed to work out.

I followed a recipe in John Palmer and Jamil Zainashef's Brewing Classic Styles..
The American Pale ale OG at 1051 was on the money.. and mash temp at 68C was about right too.

The only thing that isn't playing out is the FG (so far!). I'll check the wort in a couple of days, and if it hasn't shifted.. I might pitch some more yeast.

Kieran,

If you you mashed in at 69C your finishing gravity is exactly where I'd expect it. It's where the temp starts that is important, not where it finally ends up.
Try your next mash at MAX 65c & all should be fine - Get a cheap mercury thermometer to calibrate your mash thermometer at 65c.

cheers Ross

 

[mje1980]

Mashing at 68C and finishing at 1.020 is par for the course.

68C is "overly warm".

Try one at 62C and see where your FG lands.

I think 1.020 FG is way too high. I have no problems mashing around 67-68 getting beers to come down to 1.012, easily. I have a 1.060 mild, mashed at 67, with 17% crystal, sitting at 1.012, ready to bottle. I would be annoyed if it didn't get past 1.016, let alone 1.020. I like them this way though, some people enjoy fuller bodied beers.

 

[kieran]

Kieran,

If you you mashed in at 69C your finishing gravity is exactly where I'd expect it. It's where the temp starts that is important, not where it finally ends up.
Try your next mash at MAX 65c & all should be fine - Get a cheap mercury thermometer to calibrate your mash thermometer at 65c.

cheers Ross

Hi Ross,
So do you think I've toasted Beta Amylase?
I guess if this was the reality, I definately have.

A couple of degrees definately makes a difference.

I wanted body.. perhaps I got too much. I just re-checked the suggested mash temp from Jamil/John Palmer's recipe.. and it was 67C.
Duly noted. I should know a lot better than this.

It was a thin mash too, at 4L/kg (John Palmer limits -- http://www.howtobrew.com/section3/chapter14-6.html ) so it would be extra-toasted due to the increased thermal mass @ 69C holding longer.

 

[ekul]

There's been a few threads like this lately, and it always ends up that the person is using a refractometer to take their FG measurements. Are you using a refractometer to take your gravity measurements? Once theres alcohol in the mix it can skew the measurements.

 

[kieran]

There's been a few threads like this lately, and it always ends up that the person is using a refractometer to take their FG measurements. Are you using a refractometer to take your gravity measurements? Once theres alcohol in the mix it can skew the measurements.

No. I was using one in the past, but have been using a Hydrometer for the last 8 months.

 

[kieran]

Hi Ross,
So do you think I've toasted Beta Amylase?
I guess if this was the reality, I definately have.

A couple of degrees definately makes a difference.

I wanted body.. perhaps I got too much. I just re-checked the suggested mash temp from Jamil/John Palmer's recipe.. and it was 67C.
Duly noted. I should know a lot better than this.

It was a thin mash too, at 4L/kg (John Palmer limits -- http://www.howtobrew.com/section3/chapter14-6.html ) so it would be extra-toasted due to the increased thermal mass @ 69C holding longer.

Replying to myself here.. as a side note. Perhaps it's a combination of thermometer drift by a couple of degrees and a slightly warmer deliberate mash temp.
My last few brews were also done at "69" to "67" and they fermented out to 1014 and 1012 respectively. So perhaps the thermometer has gone out by a degree or so, and that has caused this.

So if I was to mash in with a target of 66C how light is the body going to be? In case you hadn't noticed, I like malty beers.