Normally you wouldn’t associate the smell of sour milk with bread or yeast, so you wouldn’t expect a starter to smell like that. But this is actually a very common smell for a sourdough starter.
Sourdough starters can develop a wide range of smells, which can be very similar to the smell of sour milk. Both of them undergo the fermentation process, which creates lactic acid that gives them a specific smell.
For new sourdough bakers this might be a little too much information at once, so let’s break things down to a simpler form.
Why Your Sourdough Starter Smells Like Alcohol
When you create the starter you mix water and flour, after a while the bacteria that naturally live in the flour will come to life and they will start to eat the sugar and the starch found in the flour, and they will start producing acetic acid and lactic acid. The same lactic acid is also found in most milk-based products.
And if you didn’t know about the bacteria and you want to know more about them you can check out this article: Does Sourdough Contain Probiotics? (+ What They Do) But just to put any doubts to rest I will tell you right now that those are good bacteria that are good for your health, and they don’t even make it to the bread, but more about that in the article that I linked to.
A healthy sourdough shouldn’t have a powerful smell, you should only be able to feel it if you get really close, and even then you should only feel a small hint.
If your starter has a really strong smell similar to that of sour milk, then the problem with your starter is that it’s hungry. When the bacteria consume all the sugar and starch from the flour that you added last time, the smell of the acid will become much more pronounced.
How to Fix Your Starter
To get rid of the sour milk smell of your starter you simply have to feed it by throwing out some of the starter and adding new flour and water.
And that’s it, that’s how you solve this problem, you simply have to feed your starter. But solving the problem once won’t be enough, what you really want is to prevent it from happening again.
How to Prevent Your Starter From Smelling Like Sour Milk
The smell is caused by hunger, so you have to prevent your starter from going hungry, and there are a few ways in which you can do this.
The first option would be to feed it more often, this method will work without fail. But, most starters should be fed once per day, not twice, so we have to look at why your starter is hungrier than it should be.
The second option that you have is to store your starter at a proper temperature. The main thing that makes the bacteria more active, and hungrier than they usually are, is heat. The average temperature at which you should be storing your starter is 75°F (24°C). If you keep your starter at a temperature that is higher than this, then it will become more active and go hungry faster.
The third option is to store the starter in the fridge, this will considerably slow down the fermentation process, and you won’t even have to feed your starter daily. When I do this I usually feed my starter once every 2 or 3 days. This is what I do when I don’t plan on using my starter for a while. But if you want to bake soon, you shouldn’t do this, as it will make the starter less effective.
If you are going to store your starter in the fridge, you should know that you have to take it out one week before you use it to make sourdough bread, this way the starter will be back to full strength.
If your starter is brand new you should also know that the smell will tone down on its own over time.
The Sour Milk Smell Will Tone Down Over Time
If your starter is not even 2 weeks old, then it’s quite normal for it to have a stronger smell.
The bacteria that live in the starter are quite fragile and exposed at the beginning. In order to ensure their survival, they will create a lot of acids that will stop other bacteria from entering the starter. So during the first few weeks, they will produce as much acid as they can, and as a side effect, the starter will have a more intense smell.
From my experience, the smell should tone down in one or two weeks, if your starter is brand new. That is the amount of time the good bacteria need to make the starter safe for them.
Another thing to keep in mind is that if your starter is new and the smell is very sharp you shouldn’t use it for baking yet, while there is nothing dangerous for you, there is a good chance that the bread will have a very sour taste, or it won’t rise properly.
And the last thing that you should know is that the smell can also change over time.
The Smell Will Change Over Time
Sourdough starters can, and will, change their smell over time. Some of them will only change it slightly, while others can a quire a completely new smell.
The smell of a starter is influenced by a lot of things. Some of them are completely under our control, like the type of flour used, while others are completely out of our control, like the quality of the air.
And even if you don’t change anything about how you maintain your starter, its smell can still change over time
Over the years I’ve made quite a few starters and most of them started off with a nice and pleasant sweat yeasty smell, but after a few days, they started smelling either like alcohol or like sour milk. And after even more time has passed some of them smelled the same, and others changed their smell even more. But all of them worked perfectly when I used them to make sourdough bread.
So you shouldn’t worry about the smell of your starter, the only thing that you have to care about is the intensity, the stronger the smell, the hungrier the starter.
People often believe that a bad smell is a sign that the sourdough starter has gone bad, but this is completely false. The only smell that you don’t want to come from your starter is that of mold. But this smell is usually accompanied by the actual mold, so it’s quite hard to miss.
If you want to know what are the signs that a starter has gone bad, and what are some false signs you should check out this article: Is Homemade Sourdough Bread Safe? (The Final Verdict) In this article, I address the most common concerns people have about homemade sourdough.
Final Thoughts
So while you don’t want a strong sour milk smell coming from your starter, just a small hint is nothing bad, it’s actually something completely normal.
And even when your starter has a strong intense smell, it’s not a big problem, it only means that your need to feed your starter.
Common Questions
What should I do if my starter has very few bubbles? Bubbles are created by the good bacteria that live in the starter when they eat. Having just a few bubbles means that the starter needs more food, so it requires more flour.
My starter was really active on days 2 and 3, and then there was zero activity. Is this bad? This is a very common thing. Most starters have a surge in activity during the first few days then scale down the activity. After a period it will regulate its activity.
Why is my sourdough starter so sticky? Depending on the amount of flour and water used, sometimes sourdough can become sticky, but this is usually common for starters that have more flour than water.
What is a 100% hydration starter? A 100% Hydration starter is a starter that contains equal parts of flour and water. As the name implies, for every gram of flour there is one gram of water to hydrate it, thus it’s named 100% hydration.
My starter doesn’t rise enough, what should I do? The most common cause for a starter that isn’t rising enough is excessive discarding. If you discard too much of the starter it won’t have enough resources to rise properly.
What is a feeding ratio? Feeding ratios are usually written like this: 1:1:1, 1:2:2, 3:1:1. And they refer to the amount of starter left, the amount of flour added to the starter, and the amount of water added to the starter. Here are a few examples:
- 1:1:1 – equal amounts of starter, flour, and water – 100 grams of starter, 100 grams of flour, and 100 grams of water
- 2:1:1 – 200 grams of starter, 100 grams of flour, and 100 grams of water
- 1:2:2 – 100 grams of starter, 200 grams of flour, and 200 grams of water
When can I start using a different type of flour? While there isn’t an exact amount of time specified anywhere, I would advise you to at least wait two weeks after you made your starter. At this point, the starter should have a good balance that will allow it to successfully accommodate the new flour.