US-04 banana esters

[Hop_Stuff]

Hi All

I brewed up a Coopers Stout kit with specialty grains yesterday. The airlock is bubbling away nicely but I just had a whiff out of it and I'm getting some serious banana esters. It reminds me of an extract brew I did last year when I was less experienced but I put this down to a high fermenting temperature.

I rehydrated the yeast and pitched into the wort which had cooled to 19 degrees. It's currently in a cupboard and the ambient temp is 19.8 degrees, thermometer sticker is saying that the wort is about 22 degrees. I know that this is slightly warmer than ideal but is it high enough to be creating these aromas? Some parts of the krausen are quite brown too, I'm hoping this is just bits of grain but let me know if you think it's infected.

I don't usually panic but the beer I brewed last year with the banana smell really sucked!

Brew notes below if helpful. Any words of wisdom would be appreciated!

Cheers

Ingredients

1 Coopers stout kit
Coopers Brew Enhancer 1
75g Carafa Special III
200g Chocolate Malt
300g Dark Crystal Malt
200g Lactose

Method

Cold steep 75g Carafa Special III and 200g of chocolate malt in fridge for 24 hours*

Mash 300g dark crystal malt for 1 hour. Start temp 71 degrees, kept it above 65

Added cold steeped grains and sparged dark crystal. Added BE1 and boiled for 45 mins. Total boil volume about 6L

Cooled wort and added it to fermenter with c 2kg of ice. Added lactose and topped with water to 20L

Rehydrated US-04 at 31 degrees for approx 25 mins. Pitched at 19 degrees

OG: 1.052


View attachment ImageUploadedByTapatalk1445884222.132181.jpg

 

[MyQul]

Esters can come from stressed yeast too: underpitching, large temps swings

 

[Hop_Stuff]

Hey there

Hoping that the yeast wasn't too stressed due to the rehydrating and the temp has only fluctuated a degree or too. May simply be too warm, who knows?!

 

[MyQul]

S04 ferments quite fast and can consequently kick out quite some heat. You OG isn't gigantic but decent enough so plenty of fuel for the S04 to munch and build up some heat

 

[clibit]

Reading around, it seems that S04 needs be kept below 20C, and under-pitching can make things worse, as MQ says.

 

[MyQul]

Reading around, it seems that S04 needs be kept below 20C, and under-pitching can make things worse, as MQ says.

Pretty sure S04 can go up to 25C like US-05, I'd have to check but I think thats what it says on the packet although at those temps it going to be definately kicking out esters

 

[brisboy]

I just did a beer with s-04 that got up to those temps and yes, it's very estery but not unpleasant. No banana that I can detect.

 

[clibit]

Reading threads about S04, some people get banana in the 22-25 range. Some don't. Which suggests it's aggravated by under pitching or poor yeast health. I don't use S04 myself, not keen.

 

[MyQul]

Last time I used it (on a bitter) There was a strong bready smell when I opened the FV to bottle. No bread taste though

 

[Hop_Stuff]

Thanks folks, I'll see how it goes. Think I'll stick with US-05 next time

 

[rodabod]

I've had banana esters at 22c before. They will fade with time in the bottle. Don't worry too much about it.

 

[Hop_Stuff]

Hi all,

Just got back from holiday and I've taken a gravity reading... 3 weeks to the day since brew day.

It's at 1.030!

I reckon the temperature whilst I've been gone would have been around 17 degrees so I don't know what has gone on here. Maybe the yeast was just a dodgy pack?

It's not tasting terrible... but not tasting great either. I think I'll just bottle it and give it some time although I am a bit worried that I'll get bottle bombs once I prime it.

Any ideas?!

 

[rodabod]

They will be bombs.....

Rouse and raise the temperature to low 20s, then check the gravity in a few days.

 

[Hop_Stuff]

Temperature raised and half a pack of US-04 pitched... No change. I don't have any kegs so afraid I'm going to have to dump this batch

 

[rodabod]

Temperature raised and half a pack of US-04 pitched... No change. I don't have any kegs so afraid I'm going to have to dump this batch

Given that you are considering dumping it (has the gravity not moved at all?), I'd maybe try whisking it with a sanitised whisk, then give it a couple of days to see if you get any activity.

Remember that lactose may add a few points to your FG.

 

[TartanSpecial]

you could try restarting with Nottingham (eg Wilko Gervin or Gervin G12 or NBS Ale yeast) though I'd probably use a starter so you are adding active fermenting yeast since they will get a bit of a shock going in. Question is how much money you want to throw at it for a rescue attempt (wilko gervin only £1.75 if you've got a wilko near you). Looking forward, I've found Nottingham to be reliable for bitters and seems to be more tolerant than 04 for temp swings etc..

 

[Cwrw666]

Before you tip the stuff away, go on ebay and see if you can get some amylase enzyme. I had one batch stuck at 1020 and it got it down to 1014 or something. It converts short chain starches and complex sugars into simple sugars that yeast can ferment.