How to Make a Sourdough Starter

A sourdough starter is a fermented mixture of flour and water. Flour naturally contains wild yeast and bacteria. When flour is mixed with water and kept at a warm temperature, these microorganisms begin to multiply.
The wild yeast produces carbon dioxide, which helps bread dough rise. Lactic acid bacteria create the mild acidity and complex flavor associated with sourdough bread.
A healthy starter should be bubbly, pleasantly sour, and able to increase noticeably in volume after feeding.

You will need:

• a clean glass jar (500–750 ml)
• a digital kitchen scale
• a spoon or small spatula
• flour
• water
• a loose-fitting lid or clean cloth

A digital scale is strongly recommended. Measuring flour and water by weight is much more accurate than using cups.

For the first day:

• 50 g whole wheat flour
• 50 g water.

For daily feedings:

• 30 g sourdough starter
• 30 g flour
• 30 g water.

You may increase the quantities later, but small feedings are more economical while the starter is developing.

Whole wheat flour is an excellent choice for beginning a sourdough starter because it contains more minerals, nutrients, and microorganisms than highly refined white flour.
Rye flour also works very well and often produces visible activity quickly.
You can make a starter with all-purpose flour or bread flour, but it may take slightly longer to become active.
A practical method is to begin with whole wheat or rye flour and gradually switch to white bread flour after the starter becomes established.

Use clean water at room temperature or slightly warm water, around 24–27°C.
If your tap water has a strong chlorine smell, use filtered or bottled water. Chlorine can sometimes slow fermentation.
Do not use hot water. High temperatures can damage the wild yeast and bacteria that you are trying to cultivate.

A new starter develops best at approximately 24–27°C.
At lower temperatures, fermentation will be slower. At temperatures above 30°C, the starter may become overly acidic and unstable.
Keep the jar away from direct sunlight, radiators, and hot kitchen appliances. A warm cupboard, an oven with only the light turned on, or a place near—not directly on—a warm appliance can work well.
Always check the temperature before leaving the starter in a warm location.

Place 50 g of whole wheat flour and 50 g of water in a clean jar.
Mix thoroughly until no dry flour remains. The mixture should look like a thick batter or paste.
Scrape down the sides of the jar. Mark the level of the mixture with a rubber band or washable marker. This will make it easier to see whether the starter rises.
Cover the jar loosely. Do not seal it completely airtight.
Leave it at room temperature for approximately 24 hours.
You may not see any activity during the first day. This is completely normal.

After 24 hours, inspect the starter.
You may see a few small bubbles, a slight increase in volume, or no visible change at all. Any of these outcomes can be normal.
Remove most of the mixture, leaving 30 g in the jar.
Add:

• 30 g flour
• 30 g water

Mix well, mark the new level, cover loosely, and leave for another 24 hours.
Discarding part of the starter before feeding keeps the acidity under control and prevents the quantity from becoming unnecessarily large.

On the third day, the starter may suddenly rise dramatically. It may double or even triple in volume and then collapse.
This early burst of activity is sometimes called a false rise. It is usually caused by different bacteria that become active before the sourdough culture stabilizes.
This does not necessarily mean the starter is ready for baking.
The smell may also become strong or unpleasant. It can smell cheesy, sharp, sour, fruity, or slightly strange. During the early stages, the microbial balance is still changing.
Leave 30 g of starter in the jar and feed it with

• 30 g flour
• 30 g water.

Mix, mark the level, and leave it for another 24 hours.

Many beginners become worried on the fourth day because the starter may appear less active than it was on day three.
This quiet stage is normal.
The early bacterial population is changing, and the wild yeast and lactic acid bacteria are gradually establishing a more stable environment.
Continue feeding the starter once every 24 hours.
Leave 30 g of starter and add:

• 30 g flour
• 30 g water.

Keep the starter warm and be patient.
Do not add commercial yeast, sugar, honey, or fruit to force activity. Flour and water are enough.

By day five, you may begin to notice more regular signs of fermentation.
The starter may:

• contain bubbles throughout the mixture
• rise gradually after feeding
• develop a mildly sour or fruity aroma
• look lighter and more aerated.

Continue the same feeding routine.
Keep 30 g of starter and feed it with 30 g flour and 30 g water.
If the starter rises and falls within 24 hours, begin paying attention to how long it takes to reach its highest point.

By days six or seven, an active starter may begin doubling in volume within approximately 4–8 hours after feeding.
However, not every starter will be ready by day seven. Temperature, flour quality, water, and the local environment all influence fermentation.
Continue feeding once every 24 hours if the starter rises slowly.
If it rises, peaks, and collapses much earlier than the next feeding, you can begin feeding it every 12 hours.
For each feeding, use:

• 30 g starter
• 30 g flour
• 30 g water.

This is a 1:1:1 feeding ratio by weight.

The float test involves placing a small spoonful of starter in water. If it floats, some bakers consider it ready for baking.
However, this test is not always reliable. A mature starter may sink if it has been stirred, if it is made with whole-grain flour, or if it has already passed its peak.
The rise after feeding is a much better indicator.
If your starter consistently doubles within several hours, it is usually ready to use.

A starter may develop slowly for several reasons

The room is too cold
Below approximately 21°C, fermentation may be very slow. Move the jar to a warmer location.

The water contains too much chlorine
Try filtered or bottled water.

The flour is highly refined
Add some whole wheat or rye flour to the next few feedings.

The starter is being fed too frequently
Ifthe starter is weak and has not yet risen, feeding it too often can dilute the developing microorganisms. During the early days, wait approximately 24 hours between feedings unless the starter is already rising and collapsing sooner.

The starter simply needs more time
Some starters are ready in a week. Others need two weeks or longer. Continue feeding as long as there is no mold or clearly rotten smell.

Why Does My Starter Smell Like Acetone?
An acetone-like or nail-polish-remover smell usually means the starter is hungry.
Feed it more frequently or use a larger feeding ratio.
For example, use:

• 20 g starter;
• 40 g flour;
• 40 g water.

This is a 1:2:2 feeding ratio.
A hungry starter is not necessarily spoiled.

Once the starter is established, you can feed it according to your baking schedule.
For a basic feeding, combine:

• 20 g mature starter
• 40 g water
• 40 g flour.

Mix well and leave at room temperature until it reaches its peak.
Use the starter in bread dough while it is at or close to its highest point, when the surface is still slightly domed and the starter is full of bubbles.

Making a sourdough starter is a process of observation rather than strict timing.
During the first week, the starter may rise quickly, become quiet, smell strange, and then become active again. These changes are part of the natural fermentation process.
Keep the starter warm, use accurate measurements, feed it consistently, and give it enough time.
Once it doubles predictably after feeding and repeats this behavior for several days, you have a mature sourdough starter that can be used to bake bread, rolls, pizza, focaccia, and many other naturally fermented products.