Please Help - Oil Content/Slick Preventing Head Formation & Retention in Dark Beer

[Luke Eustace]

Morning all,

I've been brewing for nearly four years... In that time, I've brewed 85 batches of all-grain beer. Of those 85 batches, five have been stouts. All five have been affected by a fault that can best be described as a slick of oil that sits on top of the beer, preventing head formation and retention. Outside of this, the beers are fine. They taste fine, they smell fine, they look fine, but are ultimately spoilt by the flat soda-like appearance, which significantly impacts the drinking experience.

So, I know what's causing the issue (oil), but what I'm failing to work out is where the oil is coming from. Here are some thoughts which have helped me work out what's not going wrong; and they all pretty much come back to the thought that "If it was X, then I should be seeing the same issues in my other beers":

Sanitation/cleanliness - if this were a sanitation issue, I would expect to see it in my other beers which have had the same sanitation regimen and same goes for glassware.

Water - I use the same water in my dark beers as I do in all my others. It's treated with the same salts and lactic acid for pH adjustment.

Fresh ingredients - given these beers have been brewed over the course of nearly four years, I am making an assumption that the ingredients haven't been stale, at least not every time. I should also note that I am not using adjuncts, like cocoa or coconut, which I know can cause similar issues.

Yeast - I have used different yeasts between batches, Fermentis US-05 & S-04 & Nottingham. Fresh packets & starters/two-packs.

Protein content of the grist - I really don't think that this is a recipe issue as far as the standard narrative around protein & foam stability. I get great head retention in my hoppy beers and lagers, which are 100% pils or pale malt and I'm obviously using a decent amount of crystal/oats/roasted malts here which purportedly encourage head retention.

I've attached a video to show you exactly what's happening with these beers as well. I should note that I see the same thing when swirling the fermenter as early a day two of fermentation (hence it's not a beer line/serving issue). Also attached is an example of a recipe, just in case you think there's anything immediately obvious.

I've really struggled to find anyone else experiencing this issue, but I hope someone here may be able to help!

Thanks in advance!

Luke

 

[Sidney Harbour-Bridge]

is the mash schedule the same as your pale ales and lagers?

 

[Luke Eustace]

is the mash schedule the same as your pale ales and lagers?

Yeah, single infusion. 67-68c.

 

[wide eyed and legless]

Oats have an oil content but many of us use it in stouts without any problem. I prefer flaked barley in my stouts

Oats​

Oats are low in starch, high in oil and protein and extremely high in beta glucans. As a result, they are not used as a major substitute for malt in the grist. However, they add a smoothness and increased mouthfeel to beers and have become popular as an additive to stouts.

 

[Sidney Harbour-Bridge]

Yeah, single infusion. 67-68c.

I was thinking you might be doing a step mash to break down some of the gums and inadvertently breaking down proteins that help with head

 

[Sidney Harbour-Bridge]

Oats have an oil content but many of us use it in stouts without any problem. I prefer flaked barley in my stouts

Oats​

Oats are low in starch, high in oil and protein and extremely high in beta glucans. As a result, they are not used as a major substitute for malt in the grist. However, they add a smoothness and increased mouthfeel to beers and have become popular as an additive to stouts.

View attachment 122460

View attachment 122461

Looks like you sculled that in one

 

[wide eyed and legless]

Looks like you sculled that in one

No a bit too strong and bitter for that, no more than 3 swallows at a time.

 

[gap]

Are you measuring PH before adding lactic acid? with a reasonable proportion of dark grains you should not need to be lowering PH it would be more usual to be looking at raising PH. I am not necessarily saying that is the cause of the oil slick

 

[Luke Eustace]

Are you measuring PH before adding lactic acid? with a reasonable proportion of dark grains you should not need to be lowering PH it would be more usual to be looking at raising PH. I am not necessarily saying that is the cause of the oil slick

Hey mate, mash pH was 5.28 after the addition so wouldn’t foresee any issues there. I added less lactic than what I would for a beer without those dark grains. Thanks

 

[Luke Eustace]

Oats have an oil content but many of us use it in stouts without any problem. I prefer flaked barley in my stouts

Oats​

Oats are low in starch, high in oil and protein and extremely high in beta glucans. As a result, they are not used as a major substitute for malt in the grist. However, they add a smoothness and increased mouthfeel to beers and have become popular as an additive to stouts.

View attachment 122460

View attachment 122461

Thanks - I’ve consisted that, but at 4% of the grist I am not confident that there would be issues. I use a shitload more oats in my hazy beers which have none of the same issues.

 

[wide eyed and legless]

Hey mate, mash pH was 5.28 after the addition so wouldn’t foresee any issues there. I added less lactic than what I would for a beer without those dark grains. Thanks

But are you measuring your mash pH? Can't just go off predicted.

 

[MHB]

First impression is that two things stand out as possible places to look.

First - Oats
I agree with WEAL and would probably use flaked barley. But its only 4.6% of your grist, so it really shouldn’t be a big problem. That said oats supplied through malt stockist are very different to the oats that we use to make porridge, much lower in lipids (fats and oils), Beta Glucans and gel forming material. Good brewing oats make pretty thin porridge.
Might be worth looking at the oats you are using.

Second - your boil
I see you are only doing a 40 minute boil. For a stout I wouldn’t consider boiling for less than 90 minutes perhaps more depending on the ingredients.
Nearly all the lipids wind up in the hot break, the amount of hot break is very boil time dependant and as a product, so is the lipid reduction.

Often in brewing it isn’t one single thing, highly hopped beers will always have much better head holding properties than lightly hopped beers. If you are adding a bit more lipids and less hops, then not reducing the lipids enough through a short boil, well all the parts add up.
There are head improvers that you can add (big head powder), Zinc (a little goes a long way, works in conjunction with isomerised hop products). There are also head improving processes like a Glucan mash rest, longer boil, maturity...
Mark

 

[Luke Eustace]

But are you measuring your mash pH? Can't just go off predicted.

Yep, that’s measured.

 

[Luke Eustace]

First impression is that two things stand out as possible places to look.

First - Oats
I agree with WEAL and would probably use flaked barley. But its only 4.6% of your grist, so it really shouldn’t be a big problem. That said oats supplied through malt stockist are very different to the oats that we use to make porridge, much lower in lipids (fats and oils), Beta Glucans and gel forming material. Good brewing oats make pretty thin porridge.
Might be worth looking at the oats you are using.

Second - your boil
I see you are only doing a 40 minute boil. For a stout I wouldn’t consider boiling for less than 90 minutes perhaps more depending on the ingredients.
Nearly all the lipids wind up in the hot break, the amount of hot break is very boil time dependant and as a product, so is the lipid reduction.

Often in brewing it isn’t one single thing, highly hopped beers will always have much better head holding properties than lightly hopped beers. If you are adding a bit more lipids and less hops, then not reducing the lipids enough through a short boil, well all the parts add up.
There are head improvers that you can add (big head powder), Zinc (a little goes a long way, works in conjunction with isomerised hop products). There are also head improving processes like a Glucan mash rest, longer boil, maturity...
Mark

Thanks mate.

I get the bottom point about adding certain things to aid head retention but I really don’t feel like they would aid in this case because of the oil situation. I need to do some more reading into lipids and how and why they present in beer, what they do and whether they could be the culprit.

I may try brewing another stout, one with no oats and a longer boil just to see if the issue persists. I’ve only recently started boiling for 40 minutes and again, haven’t noticed any impact in my other beers, but it’s worth a try.

Cheers!

 

[An Ankoù]

None of the ingredients you list above contain enough oil to form any kind of slick. Therefore, one of the ingredients you use only for stout has become contaminated with oil, somehow. I'd start looking at the oats first. If they're a commercial, breakfast brand look at the ingredients list on the packet to see whether they are 100% oats or whether there are any additives.
I'm 100% sure that if I made up your recipe, above, with my ingredients, there'd be no problem.

 

[Luke Eustace]

None of the ingredients you list above contain enough oil to form any kind of slick. Therefore, one of the ingredients you use only for stout has become contaminated with oil, somehow. I'd start looking at the oats first. If they're a commercial, breakfast brand look at the ingredients list on the packet to see whether they are 100% oats or whether there are any additives.
I'm 100% sure that if I made up your recipe, above, with my ingredients, there'd be no problem.

Interesting thought, thank you.

Another idea could be to source the same ingredients from another HBS and see if I get the same issue. The oats I usually use are the Macro organic quick oats from Woolies. 100% oats.

 

[Coalminer]

Take your oats and lay them out on paper towel and heat in oven 200C for 20 mins then see how much oil is on the paper
It might surprise you

 

[JDW81]

Thanks mate.

I get the bottom point about adding certain things to aid head retention but I really don’t feel like they would aid in this case because of the oil situation. I need to do some more reading into lipids and how and why they present in beer, what they do and whether they could be the culprit.

I may try brewing another stout, one with no oats and a longer boil just to see if the issue persists. I’ve only recently started boiling for 40 minutes and again, haven’t noticed any impact in my other beers, but it’s worth a try.

Cheers!

Changing one thing at a time will better highlight where your issue is. If you change both at once, it’s going to be a 50:50 guess as to which was the culprit.

make the same recipe with a longer boil (even a half batch) then make it with flaked barley/brewing oats from the LHBS Instead of the woolies ones.

JD

 

[An Ankoù]

Interesting thought, thank you.

Another idea could be to source the same ingredients from another HBS and see if I get the same issue. The oats I usually use are the Macro organic quick oats from Woolies. 100% oats.

They should be OK. I use Quaker. No point in buying them at a higher price from an HBS. Still at 9% oil content that's still a potential 27g going into your beer. Why not try subbing out the oats with flaked or torrified wheat. That'd give you a nice grainy flavour, but would change the mouthfeel slightly. Not in a bad way, just different.

 

[beerbong]

We eat a lot of oats in my house. Cooking, raw etc. For whatever reasons, the cheap home brands are definitely not as good as some other brands. Maybe it is the same when using them in your beer. The Lowan brand is best for us as food. I have used them for brewing as well, with no problems. Otherwise have bought them from HBS.