Slight tang in stout. Grain or water issue?

[AMyd666]

Hey Folks.

I'm really enjoying my sweet stout, but it's the second (first being coopers original with added mashed crystal, chocolate and roast barley) that has a slight tang to it. I don't know if it's mashing the roasted grains instead of steeping?
It's nice and I'll do it again, but I'd prefer it without. I was aiming for a roastier flavour like Loch Ness' Dark Ness, or Hawkshead Dry Stone Stout.

My recipe was nicked and scaled down from a Malt Miller recipe (for the roasted grains at least):
12 litres
1.5kg lager
750g Pale
100g chocolate
100g Roasted Barley
100g Crystal
200g Rolled Oats
120g lactose
30g EKG
5g rehydrated Safale S-O4

Would water profile affect this? I've checked the details and if I've understood correctly then it's soft with a mean ph of 8.

 

[Guybrush Threepwood]

Keen to see any possible answers to this. I bottled an Imperial Stout 2 weeks ago and it had a slight, almost sour tang to it. Never really experienced that before. I did read somewhere that adding sugar to the wort (demerera in my case, possible lactose in yours) can add a tang that dissipates over time? Mine is sitting in bottles for the next 6 months so hopefully thats the case. I also just mashed without any steeping and no visible signs of infection.

 

[strange-steve]

I don't think it's the grain or water. Yes, darker malts are more acidic which can cause a lower than ideal mash pH, especially when coupled with soft water, but I don't think that has much of an impact on post-fermentation pH.

In my experience tanginess is almost always from the yeast. I dont know much about S04 but I believe it's known to often produce a bit of a sour tang.

 

[strange-steve]

adding sugar to the wort (demerera in my case, possible lactose in yours) can add a tang

I'm dubious about that. Lactose isn't fermentable and if anything I would say it would counter sourness.

 

[Guybrush Threepwood]

I'm dubious about that. Lactose isn't fermentable and if anything I would say it would counter sourness.

Yeah, I wasn't sure but adding sugar was something (in my case) that was new to me and was also first time I experienced sourness. Likely 2 + 2 = 5 scenario.

Interesting you mention darker malts and soft water though. Living in Scotland I definitely have soft water and the recipe had a fair amount of darker malt. Sounds more likely for me

Apologies if thread hijacked!

 

[AMyd666]

No problemo. It bugs me a little. I'll try a different yeast (kveik perhaps). Thanks Steve

 

[foxy]

Sweet stout or oatmeal stout for me, I have always found it better to cold steep the grains to avoid astringent bitterness, for a dry stout I do mash the grain to get the bitterness.

 

[AMyd666]

That's what I wondered too Foxy. My Imperial Stout that's fermenting both used steeped dark grain and also kveik, so maybe it won't be astringent in comparison? Mind you it's a different beast to my current sweet stout recipe!
I've got MJ M42 so I can use that to compare another time.
Something to play about with; targeting those areas of possibility. Thanks guys.