Grainy Taste in stout

[Truman42]

I brewed this stout back in October and have had it kegged ever since. Just lately Ive noticed a sort of grain type taste to it and it has a smell that I recognise but not sure what it is.

I'm sure the smell is something I usually smell on brew day (if that makes sense) perhaps the smell of wort at the end of boil, Im not really sure I just know it smells familiar. It didnt have this grain taste or the smell when I fist started drinking it.

Any ideas or suggestions as to what it might be? Has anyone had this before? Ive brewed a few stouts and never noticed this before in any of them.


Rogue Shakespeare stout clone

Oatmeal Stout (13 C)

Type: All Grain
Batch Size: 25.00 l
Boil Size: 34.08 l
Boil Time: 90 min
End of Boil Vol: 28.08 l
Final Bottling Vol: 26.00 l
Fermentation: Ale, Two Stage
Date: 29 Oct 2013
Brewer: Troy
Asst Brewer:
Equipment: 3V System
Efficiency: 70.00 %
Est Mash Efficiency: 75.6 %
Taste Rating: 30.0
Taste Notes:



Ingredients
5.00 kg Pale Malt, Traditional Ale (Joe White) (5.9 EBC)

0.81 kg Chocolate Malt (Joe White) (750.6 EBC)

0.81 kg Crystal, Dark (Joe White) (216.7 EBC)

0.75 kg Oats, Flaked (2.0 EBC)

0.11 kg Roasted Barley (Joe White) (1398.7 EBC)

90.00 g Cascade [6.80 %] - Boil 60.0 min

30.00 g Cascade [6.80 %] - Steep/Whirlpool 0.0 min

American Ale II (Wyeast Labs #1272) [124.21 ml]

Gravity, Alcohol Content and Color
Est Original Gravity: 1.065 SG
Est Final Gravity: 1.012 SG
Estimated Alcohol by Vol: 6.9 %
Bitterness: 56.7 IBUs
Est Color: 92.1 EBC
Measured Original Gravity: 1.058 SG
Measured Final Gravity: 1.010 SG
Actual Alcohol by Vol: 6.3 %
Calories: 543.1 kcal/l

Mash Profile
Mash Name: Troy Mash, step,
Sparge Water: 19.14 l
Sparge Temperature: 77.0 C
Adjust Temp for Equipment: FALSE
Total Grain Weight: 7.48 kg
Grain Temperature: 19.0 C
Tun Temperature: 18.0 C
Mash PH: 5.20


Mash Steps

Protein Rest Add 22.43 l of water at 59.6 C

55.0 C

10 min
Saccharification Heat to 64.4 C over 15 min

64.4 C 45 min
Mash Step

Heat to 72.0 C over 4 min

72.0 C 10 min

Mash Out Heat to 77.0 C over 10 min

77.0 C 10 min

 

[jyo]

Sorry, mate, but this is a bit confusing. Stouts are renowned for having all sorts of grainy flavours and aromas.
You have huge amounts of chocolate malt and crystal in there. The taste of beers invariably change as they age. Sounds pretty normal, mate.

 

[manticle]

That's a fair amount of choc malt.

Graininess is often associated with atringency and the same/similar causes. Could be water chem, could be oversparging, sparge temp, etc.

Have you looked up causes and prevention of graininess in an off flavour wheel or descriptor to see if one of those rings true for you?
Aroxa have a taint kit for graininess which is caused by isobutryaldeyde

Looked up aldehydes in principles of brewing science and they are a main contributor to beer staling. Graininess and astringency are one descriptor Fix uses to describe their effect. Might be stale beer. Is it like wet cereal?

 

[mje1980]

750g flaked oats might contribute a grainy taste?

 

[Truman42]

It's not a roast taste that you normally get in stouts, more a grain tatste. I did some reading based on your suggestions Manticle and the description for husky/grainy off flavours in How to Brew seems to possibly match what I can taste and smell.
I have to add that I'm not very good at distinguishing what certain flavours or aromas are in my beer until someone else tells me what they can taste.hen I can usually pick it up.

I also noticed that in the description on husky grainy flavours in How to brew Palmer says....

These flavors are akin to the astringent flavors produced from the grain husks. These flavors are more evident in all-grain beers due to poor grain crushing or sparging practices. If the grain husks are shredded during crushing by the use of a Corona grain mill for instance, these husk flavors are more likely to be extracted during the sparge.

I had a lot of problems with my crush for a few brews where my grains were ripped to shreds using a drill motor which I couldn't manage to slow down enough. (Since been fixed as I now use a wiper motor)

They just seem to be more pronounced as the beer ages. I just brought the water book but it looks like Principles of brewing science will be the next book on my list.

Thanks for the help, much appreciated as always.

Edit: Our brew club just purchased an off flavour kit so I'm looking forward to learning more about this type of thing at upcoming meetings.

 

[Truman42]

750g flaked oats might contribute a grainy taste?

Its 10% which I had read was okay although at the maximum range. I have read that 30% can cause an astringent taste and grainy flavour and perhaps with my poor crush it exacerbated the problem

 

[manticle]

As a long term user of a corona, I can state that they do not necessarily shred husks. You can adjust the gap to get a good crush very easily.

From your description, I'd point at the staling aldehydes.

roast also drops pH which can lead to atringency etc - as opposed to a roasty flavour.

 

[Truman42]

Mines not a corona mill, just your standard mill from KK, but I did have the gap set to fine and my motor too fast and my grains were literally shredded to pieces.
Now that I think about it the husky taste possibly was there from the start but I think it was masked by the hop aroma. Back then I did notice a slight husky taste but didn't think much of it and didn't know that's what it was at the time and can certainly notice it more now.

I did a few brews with the same mill problem before I managed to fix it but perhaps I didn't notice it as much with a different grain bill that didn't contain as much chocolate, crystal and roasted barley. I've never had problems with staling before and I have a keg of a Hoegaarden clone which I brewed before this stout and it still tastes fine on tap.
Would you agree with my assumption? Or could something have happened to cause staling in this beer only?

I batch sparge at 77C and have never had a problem before and I use EZ water calc to get my PH and salts right.

 

[manticle]

Shredding husks is a definite possibility. Just you suggest it is getting worse which makes me associate it with ageing.

I wouldn't be surprised to find out that the compound is the same in either case but I'm guessing. Did you use chalk to get the pH right and did you measure the actual pH or just rely on EZ?

 

[Truman42]

Yeh that was my bad. I thought it was getting worse with age, but I now realise it was probably always there but the hop aroma tended to mask it somewhat when the beer was fresher. Now that the hops have subsided I can probably notice it more.

I cant remember if I used chalk or not and will have to check Ez water calc when I get home as I keep a file for each brew I do. I generally do check the PH but had dodgy ph strips for a bit there and not sure what it was. But in the past I found that my Ph was usually inline with what EZ water says it should be.

Thanks for the help.