The Fresh Loaf

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Acetone smell debate

AdmiralHip's picture
AdmiralHip

Acetone smell debate

Hi all,

So I have started a new sourdough starter, this time a stiff starter as my original died in the fridge as I was away from it for too long. So this one I feed once a day: 10g starter, 36 g water, 40 g white bread flour, 10 g whole wheat bread flour. It does not double in 12 hours, more like 20 but it maintains its height for several hours so by the time I feed it at the 24 hr mark it is still doubled in size and bubbly. It is in a plastic container with a lid. It has a strong acetone smell when I go to feed it, but the smell remains even after feeding as its growing. Searching the forum and elsewhere I see a lot of conflicting info on the acetone smell. People saying it means it's hungry so feed it, others saying to get rid of it entirely or just use a small amount to build a new starter, others saying it's fine and just the smell builds up in the container but it's not a big deal. So, I am unsure about this. I switched to a stiff starter because I read they do not have to be fed twice a day and grow more slowly which fits my schedule better. My starter grows well because of the whole wheat as for awhile I was only using the white bread flour but it was barely growing at all and I didn't want it to die. I don't have a thermostat to tell what my room temp is but it's definitely more on the colder side right now (Ireland) but very humid. I am considering transitioning this to the fridge after I bake with it, which I'm going to do today for the first time. I'm still not sure how my last starter died but I was unable to bake with it as any bread baked with it resulted in overfermented bread (even with a 1% inoculation). I contacted KAF about this, they suggested a stiff starter too. But the last starter was also extremely acetone-y and I don't know if that had anything to do with how or why it died.

Uzbek's picture
Uzbek

Did you try to blow the container after removing the lid and test the smell after that? My starter, once it starts deflating, smells very acetic, but once I purge the container the smell is much more fruity. It is only vapours, I think, that are acetic, and not the dough/starter itself.

AdmiralHip's picture
AdmiralHip

Sorry, blow the container? I actually came back with an update, I pulled off some of the starter to smell it out of the container and it's definitely more yeasty so it does seem to be that the vapours are trapped. I don't clean the jar, as I have better results that way than if I use a clean jar every time (also advice that came from these forums but I have seen contradicted elsewhere, but I don't really have any other jars to use). 

Uzbek's picture
Uzbek

Meant just blowing with your mouth into the or over the container to remove vapours.

AdmiralHip's picture
AdmiralHip

Ah, gotcha. I didn't do that but just leaving the jar open did help dissipate the smell.

suave's picture
suave

Acetic means vinegary, acetone - like nail polish remover.  Different compounds and different smells.

justkeepswimming's picture
justkeepswimming

Also, the flour combination you use for feeding can impact the scent/flavor profile. Example: my starter came from a friend, and initially had an unpleasant, extremely vinegary scent, and we didn't care for the flavor it gave the bread. She fed it 100% whole wheat. I changed it to a mix of KAF AP, freshly milled wheat, and a little freshly milled rye. It is quite active, still pretty tangy, works well for leavening bread, and is more to our preferences for flavor. 

You could always play with feeding a different flour combination to a second starter for a little while and see if you prefer that to the way you have been doing things, without putting your current starter at risk in case it doesn't go the way you want. 

Good luck!!

AdmiralHip's picture
AdmiralHip

The first starter I had I used only white flour - acetone. This time, the combo of white and whole wheat, also acetone. I also can't get a hold of any rye flour at the moment that I can have (nut allergies). 

clazar123's picture
clazar123

To encourage more yeast than lactobacillus to grow, keep it about 78-82F (26-28C?). This can be accomplished by putting it above/on top of your refrigerator. The coils transfer the heat out of the inside of the refrig and release it-usually comes up behind refrigerator. Or on the counter under a lamp that has a regular incandescent light bulb.

If it is indeed acetone smell (like nail polish remover), then the wee beasties are hungry.  Try either feeding more often or more volume of food. Keep it warm to encourage yeast over lacto growth. A very active,yeasty starter smells almost like beer/yeast. Once you see one, you won't ever forget it. For years, I thought I had an active starter. Ha! It was useable but weak. When I started prepping for my first pannetone bake, I discovered the difference.  My starter became Olympic strong and very yeasty smelling. I like using recipes with some form of preferment so I keep my starter semi-asleep in the refrigerator and build a preferment when I want to bake.

Have fun!

AdmiralHip's picture
AdmiralHip

I can't keep it above my fridge, as I only have a mini-fridge and it is built into my counter. I do not really have a warm spot in my house to keep it consistently warm unless I put it directly over my radiator but I don't keep that on all day because of heating costs. To be honest, I want to keep fermentation down so I don't have to feed it twice a day, so keeping it in a warm spot would actually speed up fermentation and would mean I'd have to feed it more often. I know what a good starter smells like, and in fact this one did smell good once I took it out of the container, it seems like the acetone smell was just stuck in the container. My question was largely why a freshly fed starter would still smell like acetone but I figured out that it was the container rather than the starter.

Uzbek's picture
Uzbek

When you just fed your starter at ratios exceeding 1:4:4, it doesn't smell acetone and will not until it peaks. It is only after it peaks and starts deflating that acetone smell comes up. Probably, 3-4 times feeding before the acetone smell comes back should get the smell normalize.