Diacetyl flavour query

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Backmanscoop

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Hi all,

After a bit of help please about diacetyl.

So the last 2 beers ive brewed, both IPA'S one at 5.5% and other at 6.8% have both had diacetyl off flavours about 2 weeks after being kegged. The diacetyl has been in the bottles also (i bottle about 4 litres off the excess over a corny keg) so cant be an infenction in the beer lines. Ive never had an infection in a beer before and given it took two weeks to assume this flavour im assuming its either taking the beer out of the fermenter too early or oxidation.
I rushed both beers, both were near expected OG and hadnt changed for a few days so i kegged (force carbed) and bottled after 10 days (fermented at a consistent 21c).
Both bathes were the first id tried to oxygenate the wort where I used an electric whisk when pouring the cooled wort into the fermenter.

Im assuming that ive either over oxygenated the beer or not given the yeast a chance to clear up the acetyl. Any help is appreciated.

Thanks
 
KIT or WG? as KIT removes loads of what if's. But mainly how is your sanitisation? :oops: , I use Starsan for microb and Chlorine for wild yeasts as I need to up here.
Anyway, FYI, my brews can sit in the FV 2-3weeks after last fermentation ceases as long as the FV is sealed,,, (no stray wild yeasts,or bacteria) Keep the FV sealed, until kegged and spray everything with SS when kegging,,,

I was advised hot wort must be below 27*C before oxygenation? Was your FV not open when you did the whisking? - Is this not a cross contamination risk? Can you not seal FV and do the FV shaky shake as I do for 1 min to a rock classic before pitching yeast? What temp did you pitch? was the wort and yeast matched for temp? and with what? (re-hydrated dried, wet etc)
Just ideas to consider!!
 
I may be wrong but diacetyl isnt caused by improper sanitization, more stressed yeast i think, at 5.5% and 6.8% abv's you may be border line what the yeast can handle. Try 2 sachets of yeast next time and as druncan says above, if you rehydrate your yeast then make sure the wort and yeast are at the same or near as damn it temperature. As for oxygenating, I dont bother as i see it as too much of a risk of introducing air borne bacteria or wild yeast, if you pour your wort in to the fermenter from a decent height it should put all the oxygen in required.
 
Hi all,



After a bit of help please about diacetyl.



So the last 2 beers ive brewed, both IPA'S one at 5.5% and other at 6.8% have both had diacetyl off flavours about 2 weeks after being kegged. The diacetyl has been in the bottles also (i bottle about 4 litres off the excess over a corny keg) so cant be an infenction in the beer lines. Ive never had an infection in a beer before and given it took two weeks to assume this flavour im assuming its either taking the beer out of the fermenter too early or oxidation.

I rushed both beers, both were near expected OG and hadnt changed for a few days so i kegged (force carbed) and bottled after 10 days (fermented at a consistent 21c).

Both bathes were the first id tried to oxygenate the wort where I used an electric whisk when pouring the cooled wort into the fermenter.



Im assuming that ive either over oxygenated the beer or not given the yeast a chance to clear up the acetyl. Any help is appreciated.



Thanks



I don't mean to be rude but can you explain what it is your detecting in the off beer? How do you know it's diacetyl.

I'm not a bjcp judge or a trained taster but. I do know it's hard to pin point an off flavour.

I think most people would agreeing that 9/10 of home brew issues are down to infections of one type or another.

And in this case I am tended to believe it's your cause. Particularly as you are describing a few weeks for it to develop.

I would suggest you brew another batch and really pare back your process. No aeration etc.

And also either replace or super clean and sterilise your fermenter. And then also replace any transfer hoses/taps as I've seen embedded infection Bactria in those silicone hoses cause no end of problems.

As a tip a run a freshly boiled kettle of water through all of my hoses after use.

Let us know how you get on.




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Firstly, thank you for your help.

Ill admit that this is a best guess as to an off flavour as diacetyl. It's a rich, butterscotch flavour that i have previously picked up (to a lesser extent) in some belgian styles.

I use sodium percarbonate as a steriliser and pbw for cleaner.
From the above im assuming I have either over oxygenated or introduced air borne bacteria. Ill revert back to the traditional shaking of the keg when sealed to oxygenate.

I rehydrated the yeast with water that had been microwaved for a minute to sterilise and then left to drop down to circa 24C. My wort was at circa 27C when i pitched my yeast (I struggle to get below this with an inmersion chiller in summer). I also only used 1 packet, perhaps should use 2 on the stronger strength brews.

Will incorporate all of the above tips into my next back to see how i get on. I've currently got a wheat beer in the fermenter that ive left for 2 weeks on the hope to prevent the same off flavour so will find out once kegged if it's the fermenting time causing it (albeit I've used a different yeast and its a different style).
 
To quote WhiteLabs;

As yeast slow down in fermentation, they enter what is known as the stationary phase. This phase is
where beer undergoes a maturation process to develop the correct balance of flavors. One of the key
elements of maturation is diacetyl reduction. Not only do yeast produce the precursor to diacetyl, they also
consume the diacetyl produced, and enzymaticly reduce it. Yeast reabsorb diacetyl and convert it to
acetoin and subsequently to 2,3-butanediol

So the key to reducing diacetyl is to simply leave the beer alone, in contact with the yeast, until its been reabsorbed by the yeast.

I rushed both beers, both were near expected OG and hadnt changed for a few days so I kegged

It's fair to assume, if it is indeed diacetyl you're tasting, this is your answer.

I would also suggest that if present when you kegged, some oxidation might have encouraged diacetyl in the finished bottles. But one would expect the yeast to clean this up if left at a warm enough temperature for a few days while conditioning.

If you're 100% sure there was none present when you kegged, my money is on pediococcus.

Have you had the squits after drinking? :lol:
 
Embarassingly I think you might have hit the nail on the head there henteaser! It has caused a slightly more dodgy beer stomach to put it politely haha

Quick read around looks like its caused by infection and over oxygenating and can produce diacetyl as a side effect.
 
Diacetyl is always produced in beer. It's naturally accuring and is absorbed by the yeast at the end of fermentation as long as the conditions are right. Let's say you have a work horse yeast that gets to your FG within a week. The next 48 hours the yeast will absorb the diacetyl as long as the temperature is maintained or even brought up a bit. Many problems occur when people keg to early or cold crash too early.
Another thing is diacetyl doesn't come directly from the yeast. The yeast produces a byproduct, for got the name, and that turns into diacetyl. So there is this period where that chemical needs to separate while with the active yeast. If it's too early, you can sample the batch and not detect it. So you'll think it's done and keg it. Then a few days later that chemical splits and becomes diacetyl in your keg but now the yeast is becoming dormant due to pressure and temp.
 
I think the by product is simply acetyl that the yeast then clean up after running out of the easy sugars to feed on.

Thanks all for your advice, ill cut out the oxygenation as it seems an unnecessary risk and be more patient with my fermenter.

I have just got a new exciting SS kit with a tap on the fermenter so will be more easily able to take readings now to monitor how fermentation is going.
 
That's a bit of a sweeping statement.
I certainly don't agree with what you have said.
Is that what you really mean?



Yeah I really did.

Excerpt from the morebeer "off flavour" descriptions.


A Note on Sanitation:
Proper sanitation is often said to be the most important thing when it comes to making great homebrew. A perfectly crafted and flawlessly brewed beer can turn into an unpalatable mess if it is exposed to wild yeast or bacteria. Bacteria and wild yeast
can generate almost every off flavor listed above. If your beer develops a funky flavor and none of the referenced troubleshooting tips take care of the problem, you are
probably dealing with an infection. Always practice good sanitation techniques and be sure to sanitize anything and everything that will be coming into contact with the
wort or beer. Unfortunately, not much can be done to salvage a contaminated batch, but you can learn from it. If your beer becomes an unlucky victim of the nasties, evaluate your sanitation techniques and try again.

In most instances allot of home brewers try and find a cause of an off flavour in that long list. And desperately search for something long, complicated, and scientific as to why their beer hasn't turned out how it should have done. Believe in my early days of brewing that's exactly what I did.

But mostly it's been down to a poor sanitation process or non sanitary procedures. Unless your really unlucky with some bad malt/fermentation temps or old yeast/wrong pitch rates.


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