Alcohol/chemical Aroma In Beer

[benny_bjc]

Hi,

I brewed an extract beer with extra malt and hops to create a nice dry, highly bitter, flavorsome beer with lots of aroma, with an approx 6.5% -7% ABV.

I boiled 60g Cascade for 60mins
30g cascade @ 30mins
30g Amarillo @ 0mins

After 2 weeks in the bottle I tried it... and it was great, but I did notice a very slight chemical/alcohol aroma (a bit like nail polish remover) as well as the hop aroma.

I'm guessing this could be from:

The extra alcohol?

or

Large quantity of hops boiled producing an unusual aroma from the oils?

I'm also assuming that it will probably wear off over time in the bottle?

Anyone able to shed some light?

Thanks

 

[newguy]

An obvious alcohol or nail polish aroma is almost always caused by the fermentation temp being on the high side. You don't mention whether you used any sugar - sugar can compound the issue if too much was added. Unfortunately it won't go away. To lessen its obviousness, drink it very cold.

 

[buttersd70]

Palmer describes both solvent and alcoholic flavours here

As Newguy said, most likely due to high ferment temps.

 

[benny_bjc]

An obvious alcohol or nail polish aroma is almost always caused by the fermentation temp being on the high side. You don't mention whether you used any sugar - sugar can compound the issue if too much was added. Unfortunately it won't go away. To lessen its obviousness, drink it very cold.

Thats odd....

The fermenter was placed under the house with temperates reaching maximum of 20 degrees.

I used NO sugar, all malt. Bottle priming with Dextrose.

 

[oldbugman]

Thats odd....

The fermenter was placed under the house with temperates reaching maximum of 20 degrees.

I used NO sugar, all malt. Bottle priming with Dextrose.

What temp was it when you pitched the yeast? an active ferment will generate some heat by itself too

 

[benny_bjc]

What temp was it when you pitched the yeast? an active ferment will generate some heat by itself too

I'm not actually 100% sure??? but I'm sure it was in the temperature range of the yeast at the time of pitching.

Palmer describes both solvent and alcoholic flavours here

As Newguy said, most likely due to high ferment temps.

I didn't actually notice any solvent/alcoholic flavours as such - just aromas. (I don't know if that makes any difference though?)

 

[buttersd70]

If its on the nose but not on the palate, it may perhaps just be the higher abv than what you're used to? If it was fusels, I would have thought it would be harsh in flavour....

 

[benny_bjc]

Just thinking could the higher alcohol have caused the yeast to be stressed causing this slight chemical aroma?
I used only the one sachet provided. Maybe I should have used extra yeast or created a yeast starter first???

I think I read somewhere that contact with plastic can cause solventy smells?? is this correct? I have a plastic fermenter.

After 1 week in the fermenter I bottled.... no secondary fermenter.... so could the extra yeast in the bottles be a problem?

The only other thing I can think of.... after the one week ferment I racked the beer into a second fermenter to bulk prime with dextrose dissolved in warm water, then bottled. The water used to dissolve the dextrose may have been a bit warmer than the ideal temperate range... could this have caused an issue???

Just tossing things over in my mind and seeing if anyone can shed some light.

If its on the nose but not on the palate, it may perhaps just be the higher abv than what you're used to? If it was fusels, I would have thought it would be harsh in flavour....

I don't recall it being harsh in flavour... apart from lots of bitterness from all the hops used.

 

[Stuster]

That may well be not enough yeast, beer007. What yeast did you use, and what size packet was it?

Many of us use plastic fermenters with no issues of plastic tastes leaching from them.

I would certainly say that 1 week is not enough fermentation time for a 7% beer. For a bigger beer like that, the main fermentation may well have finished, but that doesn't mean it's best to bottle it then. The yeast should then be able to clean up some of the off-flavours that might have been produced during fermentation. For almost all beers, I leave them in primary for two weeks. I would certainly think this beer would have benefited from that, as well as a secondary if you're into that kind of thing.

The water dissolving the priming sugars being warm won't be an issue.

My guess is that it's just the higher alcohol level in this beer. Two weeks after bottling (and only three after you started it out) is pretty early days for a 7% beer. I'd leave it for a week or two and see how it tastes then.

 

[benny_bjc]

That may well be not enough yeast, beer007. What yeast did you use, and what size packet was it?

Many of us use plastic fermenters with no issues of plastic tastes leaching from them.

I would certainly say that 1 week is not enough fermentation time for a 7% beer. For a bigger beer like that, the main fermentation may well have finished, but that doesn't mean it's best to bottle it then. The yeast should then be able to clean up some of the off-flavours that might have been produced during fermentation. For almost all beers, I leave them in primary for two weeks. I would certainly think this beer would have benefited from that, as well as a secondary if you're into that kind of thing.

The water dissolving the priming sugars being warm won't be an issue.

My guess is that it's just the higher alcohol level in this beer. Two weeks after bottling (and only three after you started it out) is pretty early days for a 7% beer. I'd leave it for a week or two and see how it tastes then.

Thanks for the encouragement that everything will be ok.... well hopefully I was a bit worried about the warm water used to dissolve the dextrose!

As for the yeast... I used Safale S-04 supplied with the extract kit, and I think it was a 10g sachet, but I will double check.

Thanks

 

[dr K]

for goodness sake....it is infected, dump it.
As we say on Planet Kurtz, all brewers make infected beer, the good brewers know when and dump it.

K

 

[bigfridge]

for goodness sake....it is infected, dump it.
As we say on Planet Kurtz, all brewers make infected beer, the good brewers know when and dump it.

K

While I rarely get to Planet Kurtz as often as I like you have got a bad batch there caused not by a bacterial infection but tortured yeast ie for all intents an infection.

Nail polish/solvent aroma is caused by an ester - Ethyl Acetate. This has an unpleasant, prominent solvent/Airfix glue/nail polish remover aroma and tastes mouthdrying and sharp. It also increases the effects of carbonation making the beer seem more 'prickly' that it is.

Esters are produced by a reaction of an Alcohol and an Acid. The alcohol comes from Ethanol and fusel alcohols (produced at high temps) and the acid comes from varous acids that are inside the yeast cell. The reaction can only take place when an enzyme (acyl-alcohol transferase) is available. Higher fermentation temperature increase the amount of enzyme while oxygen inhibits it.

The control of esters is not that simple. They are yeast strain dependant and there is no direct relationship between yeast growth and the amout of ester produced. In this case we have a high gravity wort being under-pitched. Normally you would pitch a larger amount of active yeast when the gravity exceeds 1.050 or so.

In this case I think that you have produced more higher alcohols as the higher gravity wort has fermented at a higher temperature than you think as all the fermentation activity generates heat - more fermentation due to the higher gravity = more heat. I would expect that the actual ferment temp could be 6-8 degrees hotter than your 20 degree ambient temperature. For higher gravity worts you always need to be carefull about temperature control and yeast management. For any gravity above 1.050 you will get more fusels produced unless you pitch more yeast (two packs for this gravity 3 for a barley wine).

So we have higher Fusels (hotter ferment) and more ethanol (higher og), more enzyme produced (by the higher ferment temperature) and probably increased acids inside the yeast (from stressing it by underpitching and fermenting hotter) - which all leads naturally to the Esters that you are seeing.

As Kurtz says - dump it, it won't get any better.

For next time keep it cooler (max 15 degrees) and use two packets of yeast rehydrated in warm water.

HTH,
Dave

 

[benny_bjc]

for goodness sake....it is infected, dump it.
As we say on Planet Kurtz, all brewers make infected beer, the good brewers know when and dump it.

K

I just tried a second bottle and it has improved heaps!
The chemical aroma has completely disappeared.
Should be interesting to note how it ages being higher in alcohol and the large quantity of hops.... will need to hide a few away over Christmas!

 

[Stuster]

Good to hear. Patience is a virtue. :icon_cheers:

 

[rich_lamb]

Ahh yes, patience - or the lack of, being the cause of most brewing problems.
Hope your'e gonna take Stuster's advice and leave your beers in the fermenter for a couple of weeks (at least) fom now on.

:icon_cheers:

 

[benny_bjc]

Ahh yes, patience - or the lack of, being the cause of most brewing problems.
Hope your'e gonna take Stuster's advice and leave your beers in the fermenter for a couple of weeks (at least) fom now on.

:icon_cheers:

Yeah I will.... the only thing that concerns me is the summer heat as I do not have any cooling system and cant really afford to either.
I guess I could put it in a tub of water with ice... but I cant use the laundry sink as others will get annoyed!

 

[newguy]

All you need is maybe 10cm of water and an old t-shirt. Dress your fermenter and place it in the water bath. Evaporative cooling takes care of the rest.

 

[muckanic]

There are esters and esters. Ethyl acetate is the main nail-polish one, caused by underpitching, lack of initial oxygenation, poor wort nutrition, unsuitable carbohydrates, and compounded by high gravities. It will recede, so I would take all this "pitch it out now" stuff with a grain of salt. Esters are not fusel alcohols, although a big pool of fusels will most likely result in more higher-weight esters. Some of these can actually be pleasantly fruity, as can the fusels. Ethyl esters can also be reduced by including lipids in the wort, eg, by fermenting some of the trub. The other side of the coin is that this increases fusels, which is further evidence that they are not one and the same thing.