Get to Know Your Sourdough Starter

So now you have your own starter, now what? You might be wondering; How often do you feed it and how much do you feed it? How can you tell if it’s healthy and ready to bake with?

The truth is there are no prescriptive answers to these questions. You feed it when it’s hungry, and you give it as much food as you think it’s going to need before you use it or feed it again. And as to the healthy and ready, it tells you. Below we’ll give you some good starting guidelines, but it’s important to pay attention and observe your starter. 

Reading Your Starter after a Feed

When you stir it during a feeding, notice the consistency of it. At 100% hydration (equal parts flour and water) it should be the consistency of thick batter. Feel the resistance against the spoon. If your hands are clean then stick your finger in it and give it a little stir with your finger. Smell it and notice how the aroma at this point is ‘floury’.

What to Look for an Hour After Feeding

Give your starter another stir after an hour or so. You’ll be able to feel how it’s changed, and how the gluten has now developed a bit. Now you will notice more resistance when stirring. It will also seem more elastic. When you smell it again you’ll start to get yeasty notes from the fermentation that’s taking place. It also might be a bit floral or fruity. 

Three Hours Later (or "Peak")

Make a note of when your starter has reached peak height (it may not be at peak yet). If you notice residue on the container walls above the starter, it could have already begun to fall. Notice how long your start stays at peak before beginning to fall. How many bubbles can you see? Is it frothy? Give it a little taste and take in the aroma as you do it. Most of what we call flavor actually comes from olfaction; our sense of smell. And our olfactory sense is closely tied to memory. You probably won’t know that you know, but you’ll be storing memories away that will make sense later.

Post "Peak"

The aroma at, or just after, peak will be boozier. It may smell like beer or white wine or spirit but you’ll smell the alcohol at this point. And the more it ferments, the stronger it will smell. Give it another taste. Is it mildly acidic (sour)? What does it remind you of? 

Let it ferment longer, until it’s back down to its starting level. Give it another stir at this point. Is there still any gluten strength (elasticity) left, or has it completely degraded? If it’s still a bit hard to stir then some of those gluten bonds are still intact. It will likely still smell boozy but may have moved over into smelling more like rubbing alcohol. The taste is likely more acidic in a vinegary way, perhaps even with a slight metallic aftertaste. These are signs that it’s now out of balance and has begun to develop ‘acid load’.

The more it ferments, the lower the pH drops. Once the yeast have consumed most of the available food, the lactic acid bacteria begin to really do their thing. And while alcohol is the main byproduct of yeast fermentation, lactic and acetic acids are the main byproduct of lactic fermentation. Some acidity actually strengthens gluten, but eventually the falling pH completely breaks the gluten down, and the network holding it together collapses.

Interestingly, vigorously stirring the starter once it’s past peak will often cause it to peak again. The reason for this is two fold. First, the stirring unlocks more food for the yeast, sugars that they just couldn’t get to before. Second, adding oxygen actually flips the yeast from fermentation into another cycle called the Krebs cycle. Here they multiply exponentially so the yeast population will grow considerably in a matter of minutes.

How to Know Your Starter is Hungry

At some point, the starter will exhaust available food and the gluten will completely break down. At this point stirring it is a bit like stirring really wet sand. The smell and taste will be sharp and unpleasant. This is a hungry starter. Leave it longer and you’ll see a thin layer of liquid form on top of it after all the food has been consumed. This is called ‘hooch’ and is made up of alcohol, water and other fermentation byproducts. This starter is now very stressed. It’s neglected and starving. The yeast will be literally physically deformed from the stress if left like this too long. At this point your starter often smells like acetone (nail polish remover).

The hooch will eventually turn grey, then black. Luckily, starters are incredibly resilient. In fact, the hooch protects the culture from contamination at this point. This is ‘survival mode’ so don’t confuse resilience with happiness. Letting it go this long between feedings weakens the starter over time, and at some point it’s going to be sluggish and will require more rehab time to get it going again. It may seem to just stop growing all of a sudden, but, in truth, these conditions will have been building over time.

You want the starter to smell fruity, yeasty, with an aroma closer to beer or white wine. It should taste mildly acidic, like yoghurt or buttermilk. This is a balanced culture. So based on all the memories you will be developing, learn to keep it in this state more often than not. What seems strange and difficult to grasp at first will eventually become second nature if you put in the work and allow it to. These are the kinds of cues that will tell you the most about your starter health and current condition.

Reviving Your Starter

You’ll begin to learn that if you give it more food at a time (higher feed ratio) then it will take it longer to ripen, and will stay at peak for a longer period as well. If it’s been neglected then give it a couple of high ratio feeds (like 1:5:5) to replace the yeast with new growth and new activity. This will also knock back the acidity. If it hasn’t totally degraded and doesn’t have hooch yet, then one lower ratio feed might be enough to wake it up and get it happy again.

TL:DR

Pay attention to your starter. It will guide you if you let it. Make notes of what makes your starter happiest, it’s health at different feeds, times, etc and you’ll be able to maintain a healthy starter that will give you the best loaves. It takes time and patience, but it’s worth it!