It's not a good idea to use a sourdough starter right after feeding. Ideally you should wait at least 2-4 hours.
Generally a starter can stay at room temperature without feeding for a maximum of 3 days. After that you will need to give the starter few feedings before you can use it again. This is because it will become less strong and it will need time and food to become strong again.
Getting ready to bake
Let it rest at room temperature for about 8 to 12 hours, until bubbly. Repeat as necessary, every 12 hours, until you notice the starter doubling or tripling in volume in 6 to 8 hours. That means it's strong enough to leaven bread.
However, an old neglected sourdough starter can take 24 hours or longer to show signs of life. So, wait at least 24 hours to feed it again. (That is, unless it rises and falls all the way back down to the starting point sooner – then go ahead and feed it again.)
Overfeeding a sourdough starter will put the culture out of balance. When you don't feed your sourdough starter enough, it will become very acidic because you aren't giving it fresh flour or fresh water and the waste will build up inside the jar.
The very short answer is, your sourdough starter generally will be at its peak anything between 4 and 12 hours after feeding. The optimum time to use it will be when there are lots of bubbles at its surface and it has has physically risen to its peak level, just before deflating back down again.
Storing your sourdough starter
If you aren't intending to use your sourdough starter every day, it is best kept in the fridge. To do this, feed it as instructed above, seal the jar and then stand at room temperature for 2-3 hours (to help reinvigorate the yeast) before placing in the fridge to store.
You can leave the starter in the refrigerator for 3 to 4 days at a time between feedings. We recommend feeding sourdough starter at least twice a week for best results. Remember, if you're planning to make bread on a given day, you'll feed sourdough starter the night before you bake.
If your recipe calls for more than 227g (about 1 cup) of starter, feed it without discarding until you've reached the amount you need (plus 113g to keep and feed again).
Float Test: You can perform a float test to check if your starter is ready. Take a small spoonful of the starter and drop it into a glass of water. If it floats, it indicates that the starter is sufficiently active and ready for use.
The discard is just the sourdough starter you're not currently feeding or baking with. It's called discard because it often gets "discarded" during feeding. If you don't "discard" some starter during feeding your starter will just grow and grow and grow until you're staring in a remake of The Blob.
What if I miss feeding my sourdough starter? If you miss one of your starter feedings, it'll be just fine. Give it a feeding when you next remember it needs one, and continue with your daily feedings as usual.
Sourdough starters do not in fact breathe and therefore do not need to have access to fresh air. However, the organisms in your sourdough starter do emit carbon dioxide, which is a gas that can build up inside the jar.
It will need a lid or cover, but not something airtight: Sourdough starter emits gas, and a sealed canister can explode. If you have intermittent baking plans, you may want something that can be lidded more tightly and stashed in the refrigerator.
Once your starter is reliably doubling in size within 8 hours of being fed, it's ready to bake with — or store for future use. If you plan on refrigerating your fed starter, let it rest at room temperature for 2 hours after its feeding before stashing it in the fridge.
Ideally, sourdough should be the consistency of warm peanut butter. When it's just been fed, it should be quite thick. It's actually ok if it seems a little dry. As the starter ferments, it will absorb the flour and thin out just a little.
If your bread had a good rise and is still holding gas but got sticky while shaping, then it may be overworked. All bread dough requires a very gentle touch at this stage. If you break the gluten strands at the shaping stage by overworking the dough it will get sticky, flatten out in a blob, and won't look smooth.
If your starter has mold growing throughout it (not just a little on top), or if it smells really foul (not just super sour), or if it turns an odd color (not just gray, which is normal, but pink or green), it may be time to start over.
Keep feeding your starter, and you'll see normal activity (bubbles) return in a few days. If your starter has a bit of dark liquid on top, it's not dead! It simply means it's hungry and that it's time to feed it. Unless your starter has a pink or orange hue or is beginning to mold, you probably haven't killed it yet.
It should also look very bubbly and slightly foamy at the surface. The scent is as important as the look. Your starter should have a strong, but pleasant acidic aroma — this will yield that tangy flavor. One popular way to know that your sourdough starer is ready is to try floating a bit of it in water.
As part of the feeding process, most bakers discard some of their sourdough starter before adding fresh flour and water to the jar. This is done to refresh the acidity levels (think sweet vs. sour smell) and to manage its overall growth in size. This technique is crucial for successful sourdough bread.
The oldest sourdough starter still in use today is at Boudin Bakery in San Francisco, California. Its sourdough starter dates back to 1849. The Boudin Bakery began that year using a starter obtained from gold miners that rushed to the area the year before.