Yeast Attenuation?

[blawford]

On Sunday 5th I brewed 5am Saint from DIY Dog.

I measured OG at 1.048 (target was 1.050) and fermentation seemed to start very quickly using Wyeast 1056 (liquid smack pack), big krausen the next day.

On Monday of this week (8th day of fermentation) I took a sample before adding the dry hops, measurement was at 1.004 (target was 1.012).

The yeast says attenuation is 73-77% but the ABV calculator I used gives me an apparent attenuation of 91%.

So what has happened here? Brew day went well, nothing really to report.

I am wondering if my hydrometer is off or whether I measured the FG incorrectly? I have tested in tap water previously and it was within a point or two of 1.0. If the hydrometer was out by say 2 points at 1.00 would it be out at the same 2 points at 1.05 or is it more that the .002 is multiplied.

 

[Covrich]

How does it taste?

Kit brews OG should match what the target is because its all mixed up for you.

It could just be a freakilshly high finish but my only concern is that it may be some wild yeast in there.

 

[blawford]

How does it taste?

Kit brews OG should match what the target is because its all mixed up for you.

It could just be a freakilshly high finish but my only concern is that it may be some wild yeast in there.

It wasn't a kit brew, bought the ingredients separately following the DIY Dog PDF you can download.

Tasted and smelt good when I did the FG reading. Although much body or sweetness to it, which I was expecting having tasted the original, but this is only my 3rd brew, so what do I know. The other brews I have done have finished under target too, so I suspect it might just be a hydrometer issue. I might by a Wilko one on the way home tonight.

 

[Simonh82]

If the hydrometer is out by 0.002 in water, it will be out by the same amount when you test your beer. It doesn't multiply. the other factor is the temperature of the beer. Most hydrometers are calibrated to 20°C but check to make sure yours isn't calibrated to a different temperature or that your sample wasn't much warmer or cooler than the calibration temperature.

If a sample is warmer than the calibration point the hydrometer will read low, if it is cooler then it will read high. It it was within a few degrees it isn't really going to have made a significant difference.

It does seem like a very low finishing gravity. I would be concerned about wild yeast but other factors could be at play too. What temperature did you mash at? Did the temperature drop much during the mash? A low mash temperature could have contributed to a very fermentable wort which attenuated higher than expected.

 

[blawford]

If the hydrometer is out by 0.002 in water, it will be out by the same amount when you test your beer. It doesn't multiply. the other factor is the temperature of the beer. Most hydrometers are calibrated to 20°C but check to make sure yours isn't calibrated to a different temperature or that your sample wasn't much warmer or cooler than the calibration temperature.

If a sample is warmer than the calibration point the hydrometer will read low, if it is cooler then it will read high. It it was within a few degrees it isn't really going to have made a significant difference.

It does seem like a very low finishing gravity. I would be concerned about wild yeast but other factors could be at play too. What temperature did you mash at? Did the temperature drop much during the mash? A low mash temperature could have contributed to a very fermentable wort which attenuated higher than expected.

Mashed at 62c, which is low, but it is what the recipe says. Mash temperature was consistent throughout. Fermenter is at 19c so should have been fine for when I took the reading.

 

[Simonh82]

I think the mash temperature is your likely culpit. 62°C is very low and will have created a very fermentable wort and lower finishing gravity.

The copy of DIY Dog that I have has the mash temp at 65°C which is more standard for British and American ales. I wonder if your copy has a typo. I think they released an update which fixed a few typos and updated new recipes.

 

[Covrich]

Yes I agree 62ºc is very low.. It does sound like a plausible reason .. I always tend to just stick to the 65-67 range

 

[Brew_DD2]

What Simonh said. You have the first version of DIYDog which was riddled with typos. Second version still has a few but it generally much better. You'll just have a drier stronger version of 5am Saint. Could be genius.

 

[blawford]

The copy of DIY Dog that I have has the mash temp at 65°C which is more standard for British and American ales. I wonder if your copy has a typo. I think they released an update which fixed a few typos and updated new recipes.

Where are you seeing this? The copy of DIY Dog that I was following I only downloaded for the first time a month or so ago, I just re-downloaded DIY Dog from this page - https://www.brewdog.com/diydog and it still says 62c. The filename downloaded is "DIY DOG 101.pdf".

I was actually coming on here to say the mystery was solved, as I bought a new hydrometer to test my current one and they both gave different readings in the same sample:

With the new one being pretty much spot on versus the recipe I was following. I didn't have a chance to test them both in water to make sure the new one is correct, but I will tonight.

 

[Brew_DD2]

I stand corrected. Strangely, I have 5AM dialled into Beersmith at 65c. I wonder if it was the old version that had the mash temp at 65c. I have the new version as well (the one you have screenshot) and I just checked and it does show 62c.

Glad it turned out to be a faulty hydrometer than an over-hungry yeast. Great colour!

 

[peteplus1]

What Simonh said. You have the first version of DIYDog which was riddled with typos. Second version still has a few but it generally much better. You'll just have a drier stronger version of 5am Saint. Could be genius.

Think I may have the old version and plan to take some ideas off their diy dog. Is the new version available on their web site?

 

[Brew_DD2]

https://www.brewdog.com/diydog

There you go. It's a thing of beauty.

 

[Simonh82]

I stand corrected. Strangely, I have 5AM dialled into Beersmith at 65c. I wonder if it was the old version that had the mash temp at 65c. I have the new version as well (the one you have screenshot) and I just checked and it does show 62c.

Glad it turned out to be a faulty hydrometer than an over-hungry yeast. Great colour!

That's strange. I think I have the old one saved on my computer and the new one on my phone. 62°C does seem very low for an amber ale where you might expect a bit of body in the beer but maybe that's right.

To the OP, make sure you double check the new hydrometer in water.

As a luxury purchase I got one of these large scale hydrometers which are much easier to view. It only goes up to 1.060 but I rarely make beers that strong anyway.

 

[blawford]

To the OP, make sure you double check the new hydrometer in water.

Will try and do that tonight.

 

[Bigjas]

As a luxury purchase I got one of these large scale hydrometers which are much easier to view. It only goes up to 1.060 but I rarely make beers that strong anyway.

Thanks for the link, I often struggle to see the small graduations on my hydrometer so this will help greatly. I'll be getting one with my next grain/hop order :thumb:

Jas

 

[geetee]

I think the mash temperature is your likely culpit. 62°C is very low and will have created a very fermentable wort and lower finishing gravity.

The copy of DIY Dog that I have has the mash temp at 65°C which is more standard for British and American ales. I wonder if your copy has a typo. I think they released an update which fixed a few typos and updated new recipes.

I know the problem has been solved but just for info 62°C mash temp will give approx 88% fermentables.

 

[Simonh82]

Thanks for the link, I often struggle to see the small graduations on my hydrometer so this will help greatly. I'll be getting one with my next grain/hop order :thumb:

Jas

It's really good and much easier to read. Bear in mind you might need a slightly wider trial jar but they sell those too http://www.themaltmiller.co.uk/index.php?_a=viewProd&productId=1290.

 

[Simonh82]

I know the problem has been solved but just for info 62°C mash temp will give approx 88% fermentables.

Out of interest, how do you work that out? I use Brewer's friend for constructing recipes and I've noticed that I get the highest abv and lowest final gravity with a mash temp of 65°C. The FG raises slightly when I enter a lower mash temp, even if I extend the mash time. This isn't what I would expect, nor do I really trust it but i don't have better figures to base it on.

 

[geetee]

Out of interest, how do you work that out? I use Brewer's friend for constructing recipes and I've noticed that I get the highest abv and lowest final gravity with a mash temp of 65°C. The FG raises slightly when I enter a lower mash temp, even if I extend the mash time. This isn't what I would expect, nor do I really trust it but i don't have better figures to base it on.

It came from a training course at Brewlab, probably also referenced in Designing great beers (Ray Daniels), extract from course notes below.
In the course we work out all calculations longhand using these assumptions and I still use this method as it is easy to demonstrate to HMRC ( if required) where your ABV figures come from. I doubt they will accept the argument the " the sofware said it so it must be true"

 

[blawford]

Will try and do that tonight.

OK, so I finally got round to testing both hydrometers in 20c water and it seems neither is accurate?

I have added the complication that I broke the new hydrometer I used previously (that gave the measurement of 1.012) before testing it in water and haven't tested this new one in the sample of beer to see whether it still measures it 1.012.

Think I am going to end up returning the Wilko one, as it is made for "Beer and Wine" the scale very large and therefore hard to read in the range I need. Anyone got any recommendations for an accurate hydrometer?