Ethyl acetate or fusels?

Hi all,

I have been experiencing a consistent issue with my brews. It is a solventy, hot taste that is very distracting. It is more noticeable when brewing high gravity beers and also when using belgian, saison or wheat yeasts, but I have also noticed it in more cleaner American or english strains.

From the faultfinding descriptions in 'how to brew' I have narrowed it down to either excessive ethyl acetate or fusel alcohols. The problem is I am not able to distinguish which one of these I am tasting.

Does anyone know any methods for distinguishing between the two? If I can identify it then I can start looking into my somewhat unorthodox processes etc. to see what might be causing it.

Cheers,
Matt

Crikey we use tons of ethyl acetate in the production of adhesive in work!

Identifying I won't be able to help you on this but I know that those are produced by agitated yeast. High temp during main fermentation, fluctuations in temp, not enough minerals (that's solved by always using yeast nutrients). I think it's not about finding which one caused the taste but more or less making sure none of those things happen. Lots of people spend time and money on FV vessels, heaters, little gadgets to make brewing fun but miss the most important part of brewing, fermentation. That's where time and elbow grease needs to come in. I think you have to have a fermentation chamber no matter what. You have to keep the temp accurate with no fluctuations. You can build them super easy and cheap. Lots of ideas on YouTube.

Anyway here is a run-down of my setup:

Equipment: "Phil mill" grain mill, 50L stainless mash tun, 40L aluminium boil kettle/fermentor, copper pipe lauter manifold with silicone syphon hose, 10kW outdoor paella gas burner, corny kegging system, +other odds and ends.

Ingredients: uncrushed grain and whole vacuum packed hops from 'the malt miller.com'. Dry yeast strains used for convenience (liquid yeast used only a few times). Grain stored at room temp loosely closed bag, yeast packets in fridge, hops in freezer.

Water: realised pretty quickly that portsmouth water is not really suitable for anything apart from Stout so I have been treating my tap water since I started. I use brun 'water spreadsheet calculator to determine phosphoric acid additions to both mash and sparge water and also add equal amounts of minerals to both waters depending on beer style. End goal is a room temp ph of about 5.5. Rarely this is checked with a ph meter but mostly assumed by the spreadsheet.

Process: I have tended to attempt shortcuts in my all-grain process over the years. I started off brewing as described in 'how to brew' by John Palmer. Typical 3 vessel homebrew method of infusion mashtun ----> kettle ----> fermentor with rapid cooling to ferment temp using a copper immersion chiller. But for the last three years I have been using a cut down method in order to try and save time and simplify. This consisted of two mayor changes.... (1) I don't chill the wort after the boil. (2) I do not rack to a fermentor. I ferment directly in the kettle.

So I would mash in the 50L pot for at least an hour, sometimes more, stirring about every 15mins. Then syphon into the boil kettle for a 60min rolling boil (90 for pilsner malt), with hops added as required. Protofloc/Irish moss tablet added last ten minutes. Then I cover the pot with a few layers of cling film at flameout and then let cool for about 20 hours at room temp. Final temp adjustment before pitching yeast is done in a temperature controlled fridge.
I feel this method saves a lot of time but more importantly it guarantees an almost sterile wort and fermentor as it has been boiled for at least 60 mins.


For the dry yeast, I always rehydrate the packet using the manufacturers datasheet and use an online calculator to tell me how many grams of yeast are needed. I will then add the yeast, swirl the fermentor for a few minutes and after that I will add air using a medical syringe filter and a small aquarium pump for about 30 - 60 mins. Sometimes I will aerate with the pump first then add the yeast (30 mins) But sometimes I add the yeast first and just aerate longer (60 minutes). My logic for this is that air can only saturate wort to about 8ppm so in half an hour the yeast will have taken up the 8ppm present and then by keeping the pump on there will be another 8ppm still in the wort when the pump is switched off after 60 mins. So the yeast will see a total of about 16ppm.

Then I would ferment at 17 - 20 deg C depending on the beer in the controlled fridge for 7-14 days. After day 4 I raise the temp about a degree a day until day 7 to increase yeast activity and then hold that temp until packaging into a corny keg and carbonated with a CO2 cylinder . Fermentation temperature is measured and controlled with a thermocouple stuck to the side of the fermentor with tape and a sponge over the top to insulate the sensor from the external influence. I'm told this gives an accurate beer temperature but I have never confirmed this by measuring directly inside the pot

I looked in a book "Yeast and fermentation" By Boulton and Quain and this indicated that a potential cause of higher alcohols and sometimes esters can be overoxygenation of teh wort leading to too fast yeast growth. Similarly higher temperatures will stimulate yeast growth and increase the higher alcohols.

...interesting. .most guides say to thrash the wort to within an inch of its life before pitching. .

I don't think it's his air issue. Sounds like he is pumping in air and not bottled oxygen. So that won't be an issue.
I'm more worried about his degradation of his aluminum boil pot he stated he uses as fermentor. Minerals interact with yeast and if they have a toxic environment they'll display that is their esters and their output of alcohol.
Your pot may be fine to boil in but I would cool down a bit then transfer to a proper food grade FV then continue your cooling overnight and see what happens then. If your boil pot was stainless I wouldn't worry too much other than the residue on the pot that's left over from the boil. I'm sure that substance is a mix of hard minerals, combined proteins and other things that are not beneficial to the wort. Let's just say what's left behind in the boil kettle is things we don't want.
Try one change for the next few brews, then see the result. I'm pointing to your pot.

Frosti2k2 said:

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Process: I have tended to attempt shortcuts in my all-grain process over the years. ............. But for the last three years I have been using a cut down method in order to try and save time and simplify. ...........

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Er .... what does it taste like after it's been sat conditioning on a cool dark shelf for two or three months? :whistle: :whistle:

I've NEVER found a "shortcut" that improves the taste of a beer and as a non-commercial maker of beer I have NEVER needed to "save time".

The best time saving shortcut for obtaining cheap ready to drink beer is called "Lidl". :whistle:

Thanks Japan brew. I will definetely consider the pot as a potential cause.

As for letting it sit and condition, I have not noticed any improvement after 2 or 3 months. It is not something that seems to be able to condition away.

Frosti2k2 said:

............

As for letting it sit and condition, I have not noticed any improvement after 2 or 3 months. It is not something that seems to be able to condition away.

Click to expand...

In that case, I will quote a girlfriend of mine from many, many years ago.

"You're doing it wrong!"

:whistle: :whistle: :whistle:​

Assuming that you have at some stage brewed a decent beer, whatever you have changed since that time ...

... CHANGE BACK! :thumb:

BTW I used an aluminium pot in my early brewing days, but I didn't use it for extended boils so that would be the first thing I would look at.

The second thing would be your grain storage. "Loosely closed bag." to me means that it will absorb every bit of dampness from its surroundings and rapidly go mouldy. Personally, I store mine in a closed bin with a small de-humidifier alongside to keep the grain damp-free.

I know the hard way that hot solvent tastes can come from high fermentation temperature. The first thing that I would do is to check the temperature inside the fv to make sure the thermocouple is well calibrated.

Frosti2k2 said:

Hi all,

I have been experiencing a consistent issue with my brews. It is a solventy, hot taste that is very distracting. It is more noticeable when brewing high gravity beers and also when using belgian, saison or wheat yeasts, but I have also noticed it in more cleaner American or english strains.

From the faultfinding descriptions in 'how to brew' I have narrowed it down to either excessive ethyl acetate or fusel alcohols. The problem is I am not able to distinguish which one of these I am tasting.

Does anyone know any methods for distinguishing between the two? If I can identify it then I can start looking into my somewhat unorthodox processes etc. to see what might be causing it.

Cheers,
Matt

Click to expand...

I used to see this all the time in my brews and would only be better with low ABV ones. I found that fermentation temperature was the primary cause of this. I have corrected this with controlled fermentation temperatures and stepping up temperature towards the end of the fermentation.

From what I understand fusel alcohols are 'leftover' by products from an partially complete conversion of sugars. Yeast will go back through and work these out, it's just giving them time to do it. If the yeast is heavily stressed, you may see more of this 'flaw' which may not ultimately work itself out due to flocculation, so limiting it is ideal. Happy yeast, happy beer. Consider using oxygen on any high ABV beer(its not that expensive), pitch proper yeast rates at the proper temperature, maintain temperatures, and ramp up temperatures towards the end of fermentation to get lazy yeast going.

*Edit* I did read your process- I wish you luck!