How to Start a Sourdough Starter: A Step-by-Step Guide

 

How to Start a Sourdough Starter: A Step-by-Step Guide

Sourdough baking has taken the world by storm, and at the heart of every great loaf is a healthy sourdough starter. If you've ever wondered how to start a sourdough starter from scratch, you're in the right place! In this guide, we’ll walk you through the simple steps to create your own bubbling, active sourdough starter using just two ingredients—flour and water.

What is a Sourdough Starter? A sourdough starter is a natural leavening agent made by fermenting flour and water. The wild yeast and bacteria in the environment interact with the mixture, producing the gases and acids necessary to help your bread rise and develop a tangy flavor.

Ingredients You'll Need:

• Half cup/60g plain flour
• Quarter cup/60ml/g water (filtered or spring water is best)

Day 1: Mixing the Starter

1. In a clean glass jar or bowl, combine your flour and water.
2. Stir well until all the flour is hydrated and a thick paste forms.
3. Cover loosely with a lid to allow airflow while keeping out contaminants.
4. Store at room temperature (21-24°C) away from direct sunlight.

Day 2: Checking for Activity

1. After 24 hours, check for bubbles or a slightly sour aroma—signs that fermentation has begun.
2. If there's no activity, don’t worry! Continue feeding the starter.

Day 3-7: Daily Feedings

1. Discard half of the starter (about ½ cup) to prevent it from growing too large (don't worry, we have recipes for discard).
2. Add ½ cup (60g) of fresh flour and ¼ cup (60ml) of water.
3. Stir well and cover again.
4. Repeat this process every 24 hours.
5. By days 5-7, your starter should be bubbly, slightly tangy and well, some people bake at days 7 but its best to work for the first 2-3 weeks on strengthening your starter to get the best chance at a good first loaf.

How to Know When Your Starter is Ready

• It doubles in size within 4-6 hours of feeding.
• It has a pleasantly tangy smell (not overly sour or rotten).
• It produces bubbles and has a slightly spongy texture.
• It passes the float test: Drop a teaspoon of starter into water—if it floats, it’s a good sign that it could be ready to use (although this is just an indicator, you will still need to strengthen your starter before use, the best test is a consistent double in size 3-6 hours after feeding for 5 consecutive days).

Maintaining Your Sourdough Starter

• If baking daily, continue feeding every 24 hours.
• If baking less frequently, store in the fridge and feed weekly.
• Always discard half before feeding to keep it balanced.

Sourdough Starter Troubleshooting: FAQ

Why is my sourdough starter not bubbling?

• Your kitchen might be too cold. Try placing your starter in a warmer spot (21-24°C).
• Use filtered or dechlorinated water—chlorine can inhibit yeast growth.
• Give it more time! Some starters take up to a week to show significant activity.

Why does my starter smell bad (like rotten eggs or acetone)?

• A strong, unpleasant smell can indicate a lack of feeding. Refresh your starter with regular feedings.
• If the smell is overwhelming, discard most of it and feed with fresh flour and water.

Why is there liquid on top of my starter?

• This is called “hooch” and forms when your starter is hungry. Stir it back in or pour it off before feeding (unless you see mold).
• Increase feeding frequency if this happens often.

My starter is moldy—can I save it?

• If you see fuzzy mold, discard and start over or if you see an odd coloured film that is pink or orange).
• To prevent mold, always use clean utensils, keep a consistent feeding schedule, and store the starter in a well-ventilated container.

Why isn’t my starter doubling in size?

• It might not be mature yet—some starters take up to 10-14 days to fully develop.
• Try using whole wheat or rye flour to boost fermentation.
• Ensure you're discarding half before each feeding to maintain a balanced yeast-to-food ratio.

Can I revive a neglected sourdough starter?

• Yes! If it’s been in the fridge unfed for weeks, start feeding it daily until it regains strength.
• If it smells extremely bad or has mold, it’s best to start fresh.

Boosting Yeast Growth with Whole Wheat Flour

Whole wheat flour is a great way to encourage yeast activity in your sourdough starter. Here’s why:

• Higher Nutrient Content – Whole wheat flour contains more natural wild yeast and bacteria than refined flours, which can speed up fermentation.
• More Enzymes – It has a higher enzyme content, helping break down starches into sugars that feed the yeast.
• Better Microbial Balance – The extra minerals and fiber in whole wheat flour create an ideal environment for a healthy starter.

💡 Tip: If your starter is sluggish, try replacing half of your usual flour with whole wheat or rye for a few feedings to give it a boost!

Beware: Orange and Pink Mold on Your Sourdough Starter

If you’re nurturing a sourdough starter, keeping an eye on its health is crucial. While slight discoloration and liquid separation (hooch) can be normal, spotting pink or orange mold is a serious red flag that should never be ignored.

What Causes Pink and Orange Mold?

Unlike the natural wild yeasts and lactic acid bacteria (LAB) that make sourdough thrive, pink and orange mold signal an invasion of harmful bacteria and fungi. Some of the most common culprits include:

• Serratia marcescens – A bacteria notorious for its pink, orange, or even red pigmentation. It thrives in moist environments and is known to cause respiratory and urinary tract infections in humans. If it contaminates your starter, it can pose serious health risks.
• Aureobasidium pullulans – A type of yeast-like fungus that appears pink or orange and is commonly found in damp environments. Though less harmful than Serratia, it can trigger allergies or infections in immunocompromised individuals.
• Rhodotorula species – A pigmented yeast that can appear pink, coral, or orange. While not always harmful, its presence suggests poor starter hygiene and potential cross-contamination with other, more dangerous bacteria.

Why Is It Dangerous?

Unlike the beneficial microbes in a healthy starter, these harmful invaders can produce toxins, allergens, and even pathogenic infections. Consuming bread made from a contaminated starter can lead to food poisoning, digestive issues, or allergic reactions.

What Should You Do?

Unfortunately, there’s no saving a sourdough starter once pink or orange mold appears—you must throw it away. Even if the mold seems to be only on the surface, spores and bacteria can penetrate deep into the culture.

How to Prevent Mold in Your Starter

To keep your starter mold-free and thriving:
✅ Use clean utensils and jars – Always sterilize your container and avoid cross-contamination.
✅ Feed it regularly – A neglected starter is more vulnerable to contamination.
✅ Store in a cool, well-ventilated area – Avoid excessive moisture or heat, which encourage mold growth.
✅ Monitor for off smells – A healthy starter should smell tangy and yeasty, never musty or rotten.

When in doubt, trust your senses—if something looks or smells off, it’s better to start fresh than risk your health.

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Happy baking! 🍞✨