New to sourdough baking? Here's all you need to know about feeding sourdough starter. The starter will reward you with lively yeast and success with baking tangy Sourdough Bread!Adapted from King Arthur Flour
2cupssourdough starter, unfed, chilled or room temperature
1scant cupall-purpose flour, see Recipe Notes
½cupwater, warmed to 100 to 120°F
Remove the unfed sourdough starter from the refrigerator if that's where it's kept.
There may be a bit of light amber or clear liquid on top. Stir it back in to the starter or drain it off, your choice. Either way, it’s alcohol from the fermenting yeast and is perfectly fine. If you notice a strong, moldy or off-putting smell (like something rotten), or it has a pink or orange tint or streak, this is a sure sign that your sourdough starter has died. Don't use it! Just throw it away and get a new batch of sourdough starter.
Place a 2-cup container on a kitchen scale and remove 1 cup (227g) of the unfed sourdough starter from your sourdough container. This is the unfed sourdough starter (aka sourdough starter discard). If you reuse the discard, loosely cover it and set aside.
Warm in water in a microwave-safe measuring cup for 30 seconds or until it's warmed to 100 to 120°F as read on a digital thermometer.
Place the sourdough starter container on the scale. Measure 1 scant cup (113g) of all-purpose flour (see Recipe Notes) and add it to the starter. Next, measure ½ cup (113g) of water. Stir well. Cover and set aside.
Allow the starter to rest at room temperature (about 70°F) for 2 to 4 hours, or until it's bubbly with a nice yeasty smell, and will have risen up in the container. This means the yeast is active and feeding.
At this point you have a fed sourdough starter. If you're going to bake with the starter now, remove the amount you need and repeat the feeding process to replace what you've just taken. If you're not going to use the starter now, just return it to the refrigerator (if that's where it's kept) until the next feeding time.
My starter has a recipe ratio of 1 to 1 flour to water. That is, it has a 100% hydration level. If your hydration level is different from mine, you'll need to adjust the amount of flour in relation to the water accordingly.You can also use different types of flours for different types of sourdough starter. I use King Arthur Baking's unbleached all-purpose flour to maintain my starter, which has a higher protein level than most all-purpose flour. You can use whole wheat flour, rye flour, bread flour, etc, as your flour of choice. Just be consistent and use the same type each time, if possible.