Hunting the dreaded off-flavour.... marzipan.

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Beer666

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Which one do you mean? The biab method? How long are you boiling your wort?
I use a recirculating system with a bag. If i boil i sparge and if its raw i do a full volume mash. I generally boil for an hour or more as i have slow boil off rate. Raw beers only go up to 75c.
 
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Miraculix

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So I went back to biab for a few batches and the off flavour is gone. There is the slightest hint of it present directly after fermentation finished, but I am heavily sensitive to this particular almond flavour now and it is aging out in one or two weeks. I bet nobody else would actually notice it.

I'm happy with continuing full volume biab now, but if I wanna do high gravity batches, I'll need to get back to the classic mash ton because of volume issues of my small kettle.

I will try to limit the flow rate of the hose at the end of it by tying it together with a piece of wire. That way the hose should stay full of liquid all the time so there's no excessive oxigenation by partially filled hoses and the resulting inner turbulence.
 
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Miraculix

Miraculix

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Hmm. I drain via a silicone hose in to my BK when I sparge, usually get a little turbulence in the hose. But I have never picked up any almond flavor.
How long is the distance in the hose from vessel to vessel? Mine is approximately 1m.
 

IslandLizard

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I read the whole thread, just not thoroughly.
Silicone hose were mentioned. But could it be from any vinyl tubing used in the system, moving wort to the fermenter, or when racking? Possibly more so when or after contact with hot liquids, who knows how much it lingers?

The other thing I've noticed the past year or so, is how our chlorinated tap water left in a (plastic) cup smells and tastes marzipan/almond-paste like.
 
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Miraculix

Miraculix

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I read the whole thread, just not thoroughly.
Silicone hose were mentioned. But could it be from any vinyl tubing used in the system, moving wort to the fermenter, or when racking? Possibly more so when or after contact with hot liquids, but who knows how much it lingers?

The other thing I've noticed the past year or so, is how our chlorinated tap water left in a (plastic) cup smells and tastes marzipan/almond-paste like.
Nope, no vinyl in the process. Chlorine is not an issue in Bremen, so that's also no possibility.

Maybe it's the tap of my mash bucket? It's literally like an aeration device in combination with the hose, which is way too big for the flow rate during the lauter.
 

IslandLizard

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Maybe it's the tap of my mash bucket? It's literally like an aeration device in combination with the hose, which is way too big for the flow rate during the lauter.
You may be on to something there. Hot side aeration...

I've been underletting the mash the past 2-3 years. It's really easy, as long as one includes a calculated or estimated mash tun heat loss. It's also easier to add some cold water or ice to bring it down a few degrees than trying to raise it in a non-heated mash tun (plastic cooler). ;)
 

TheMadKing

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So @Miraculix i just wanted to update you that I got Marzipan in my latest Scottish ale.

It has 2 major flaws that I can detect:

First it's hazy and astringent because I had my mash thickness way too low for a small grain bill and ended up over sparging (meaning my end of runnings gravity was way too low, close to 1.000 I think). So I got polyphenols from the malt resulting in permanent haze and slight astringency. But hey my mash efficiency was 93%! 😁

Second, I ran out of oxygen prior to brewing it and I pump my kettle directly into my conical resulting in very low aeration. So I had a SLOOOW and poor fermentation and I raised the temp to 73F trying to get it to finish. I used WY1318 in this batch, second pitch

The main off flavor definitely comes across as marzipan or artificial cherry, but the other day I was eating a piece of French bread and took a drink right after eating the bread, and bam... Ethyl acetate. Plain as day nail polish remover

After a few more sips my taste buds re-aclimated and it shifted back to marzipan.

So I submit low level (like barely at taste threshold) Ethyl acetate as a possible cause of this flavor. Maybe it's caused by an interaction between yeast and grain husk polyphenols?
 

Bilsch

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The other thing I've noticed the past year or so, is how our chlorinated tap water left in a (plastic) cup smells and tastes marzipan/almond-paste like.
Interesting. Toluene is converted to benzaldehyde (very almond smelling) by photochlorination.
Was your cup sitting in the sunlight?
Ever had your water lab checked for aromatic hydrocarbons?
 

IslandLizard

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Interesting. Toluene is converted to benzaldehyde (very almond smelling) by photochlorination.
Was your cup sitting in the sunlight?
Ever had your water lab checked for aromatic hydrocarbons?
Yeah, interesting...

No, those cups are typically on a counter they may indeed get some early morning direct/indirect sunlight, in Summer. Hmm, you may be on to something.
The weird almond-like scent/flavor is not always, just once in a while, and it's not chlorine.

I do smell/taste the chlorine, and the levels vary widely. Sometimes it can be really strong. Not anything like a pool though, I had one, I know what that's like.

Our county's water plant has their yearly quality reports online, with no significant aromatic molecule content. If any, it's very low ppb. But maybe there are a few spikes, that remain hidden.
The water source is from deep "private" wells with a rather large distribution area. A 10 inch mains goes up the main highway for 15-20 miles before it Ts off, serving our communities to the east.

No, I haven't sent out any samples for my own report.
I'm keeping a closer eye on it.
 

Bilsch

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Our county's water plant has their yearly quality reports online, with no significant aromatic molecule content. If any, it's very low ppb. But maybe there are a few spikes, that remain hidden.
The water source is from deep "private" wells with a rather large distribution area. A 10 inch mains goes up the main highway for 15-20 miles before it Ts off, serving our communities to the east.
I had to look tolulene up myself to see if it was a common contaminant in ground water and apparently it is anywhere industry, manufacturing, refineries etc have been for a long time. I know my industry used a metric **** ton over the years although it was consumed in the process so none was discarded.
 
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Miraculix

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I have just brewed a batch of dark mild. The last bottle did not fill up completely, about 1/3 was left empty and I placed it on the heater, to force bottle carbonation. Guess what..... full blown marzipan. I did not detect it directly out of the fermenter, so it hopefully is only this extra warm and oxidised bottle. Good example for what happens when thre is headspace.
 
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