Sourdough starter developing alcohol

If you've truly gone anaerobic and the smell is off, you are growing things other than the intended cultures...

As a rule, I simply feed mine flour and water. No sugar. The cultures can get along fine with the flour. (I did read in a reputable baking book about adding leftover water from boiling potatoes, for the starches, but I haven't had a chance to try.)

If the smell is off, I would dump and start over in a more breathable container. Your entire goal is to grow the sourdough cultures and let them flourish in their happy environment. And as you've smelled, there is a distinctive scent of happy sourdough. Now if the smell has changed, you lost your scented sourdough and are now growing something else.

I've kept sourdough for over a decade, and it's from a culture that is 84 years old. But if it smells funny (or gets brightly colored mold), he's going down the sink faster than dishwater. It's just the nature of the beast.

The alcohol was not a problem in my case.

I want to clarify that my sourdough was not producing any liquid in any visible quantity, the alcoholic smell started to fade as soon as I leaved the container opened for a about a day .

I have also used the very same sourdough, without refreshing it in the meantime, for my latest baked goods and it's active and kicking .

Most likely, the yeast in your starter are getting tired and/or hungry. A starter will start developing a strong alcohol smell and start "leaking" a dark fluid once the yeast start running out of food. This happens to me if I neglect my starter for over 2 weeks or so.

I would recommend keeping your starter in the refrigerator, not at room temperature. You only need to leave it at room temperature for about 6-8 hours after feeding (or until it starts rising and appears bubbly). Keeping it cold will slow down the yeast metabolism and keep it fresher longer.

I only feed my starter an equal mix of flour and water, and make sure to at least double the size of the starter (8 oz starter needs at least 4 oz flour and 4 oz water at feeding time). Flour provides all the nutrition your yeast need, and you want a yeast culture that is well adapted to eating flour instead of other sugars. This mostly comes from my homebrewing experience; a generation of yeast raised on pure sugar start losing the ability to properly ferment beer.

Alcohol is a natural product of yeast fermentation. That it is being produced is nothing, in and of itself, to be worried about. However, keep in mind that natural "products" of any biological process tend to be the waste products, and isn't that great for the producing organism to have it accumulate. Usually we notice it more when we've neglected our cultures and a good amount has accumulated.

Just pour it off before using or feeding, and if it seems like the quality of the starter culture is degrading, start a fresh one from scratch and inoculate it with your existing one.

When you first start a fresh brand new starter mix, you have a fight of bacteria and yeast where the intent is that the yeast wins out and the alcohol that is produced by the yeast kills off the bacteria. The yeasts alcohol is what keeps the starter from going bad.

The first few batches of bread I made from fresh starter was very sour but the strong sourness went away over time.

After the first week after hopefully seeing the alcohol gas bubble being produced showing you have yeast growing you put your mix in the fridge to slow the yeast down from eating all the starches up really fast.

I've never had starter go bad yet but I smell it every week and know what it should spell like. It kind of a fruity smell after a week. When you mix in more flour, it will smell more like flower again.

I use to just feed my starter with just flour but got into blending up grapes which has my starter thriving. The alcohol gets so strong some times when I open the container, it burns my nose, but that is after sitting in the fridge for a week after a grape feed. With flower, you get a fruity kind of smell. The dark liquid on top means it needs feeding again. I feed my starter once a week and make bread every other week. I feed one cup of flour each week and make two loaves the second week. I make wheat, sunflower seed, poppy seed, cheese, spice and garlic bread.

My starter has passed 3 years old now. I've been making bread continually for 6 years now. I started with one loaf a week but got to two loaves every other week. I make my own hamburger buns too.

From my wine making days, I know that baker’s yeast will stop fermenting and producing alcohol at a lower percentage of alcohol than brewer's yeast. Someone said that 8% alcohol actually kills bakers yeast, but I don’t have confirmation of that. This applies to a yeast culture that is happily fermenting a sugary solution. 10% sugar solution is converted to approx 5% alcohol. If I was keeping yeast alive to multiply, I would rack off some of the liquid well before that. Then add fresh water, before adding any more sugar. Haven’t tried flour. This is from an old memory - hope it’s still valid.

I would tend to agree with the starved yeast producing more alcohol waste. I had a similar issue recently with both of my starters (I have an Irish wholemeal and a blended wholemeal/AP). Per my microbiologist friend's advice, I stirred the liquid (hooch) back in and did a discard and feed. I treated them like new batches for a few days, discard/feed daily and kept out with a loose cloth covering. It only took about 2 days for the whole meal to come back to a breadlike scent and back in the fridge he went. It took another day for the blended flour starter but it came around too.