*sniff*

rozeboosje

I'm posting this here because I reckon home brewers may be more knowledgeable about this particular topic than anybody in any other forum would be, considering that you, home brewers, would be dealing with similar fermentation processes and organisms that I would be dealing with as I'm trying to bake my sourdough breads ...

Anyhooooooooo. I'm trying to learn about cultures, organisms and their metabolic products, and I find out that, depending on what organisms have the upper hand, how much access to oxygen they have, how well provided with - in my case - flour they are, how wet the starter is and what temperature it's kept at, you may be able to detect such metabolic products as Pyruvate, Acetaldehyde, Ethanol, Acetyl phosphate, Lactate .... and so on.

Then you see those who are knowledgeable in the field say things like how they "can often smell diacetyl".

Oh really? I know MY starter doesn't always smell the same. Sometimes it smells lovely, almost "fruity". Sometimes, especially if it's a bit on the wet side, a bit warm, and if I forget to feed it for a day, it can smell distinctly "vinegary", and I have had to rescue it once or twice during the summer. But am I smelling "diacetyl" or any of those other chemicals? I wouldn't have the foggiest.

Wouldn't it be great if there were somewhere I could go to smell those typical fermentation metabolic products in isolation so I can learn which chemical smells exactly how, and so get a better clue as to what state my starter is in? Well... is there such a place?

BeerNut

Well, diacetyl is butter. Diacetyl is what makes butter taste buttery.

Any homebrew site will have written descriptions of which common off-flavours are caused by which chemicals, and I'll bet there are baking sites that have more sourdough-relevant information. You can also get sensory tasting kits like this.

rozeboosje

Thank you BeerNut

sharingan

If you are making a sourdough, you usually want to pitch it when your starter is freshly fed and yeast dominant.

But like BeerNut says, there are flavour wheels for detecting Beer off flavours that may be appropriate to sourdoughs.

rozeboosje

sharingan wrote: »

If you are making a sourdough, you usually want to pitch it when your starter is freshly fed and yeast dominant.

But like BeerNut says, there are flavour wheels for detecting Beer off flavours that may be appropriate to sourdoughs.

cool!

oblivious

Acetaldehyde (green apple like aroma)would be a good indication that the yeast are doing well as it an intermediate of alcohol production.

rozeboosje

oblivious wrote: »

green apple like aroma

Cheers - I think I know what smell you mean by that. And yes, my starter does sometimes smell a bit like that. Happy days!