What is Sourdough and how to maintain your Sourdough Starter Culture

Sourdough culture contains a whole array of beneficial enzymes and microorganisms, most importantly a strain of the lactic acid bacteria, (that’s the same stuff that you can find in yogurt, kefir and probiotic supplements).

What can lactic acid do?

  • Depending on the fermentation time it will break down the gluten protein naturally present in many flours. (This does not mean a person suffering from celiac disease can eat wheat bread; but it does mean that the bread will become much better digestible for people with intolerances).

  • Lactic acid produces beneficial compounds like antioxidants, the cancer-preventive peptide lunasin, and anti-allergic substances which may help in the treatment of auto-immune diseases.

  • Several hours of fermentation with sourdough is sufficient to neutralize the phytic acid that can “lock up” minerals such as iron, calcium, magnesium and zinc.

  • Bread is often avoided by people affected by metabolic syndromes, rightly perhaps in the case of industrialized white bread with a high glycemic index, but no so with sourdough bread. That’s because when heated the organic acids in sourdough cause interactions with the starch availability, making whole-grain sourdoughs one of the foods with the lowest GI.

Lactic acids destroy certain harmful bacteria and it’s anti-fungal components keep mold at bay - no need to keep sourdough bread in the fridge for storage.



Once you have a mature starter culture - like the one you got today - it’s easy to maintain it. You really only need to refresh it before you plan on baking, usually 1-2 days before a bake. In the meantime it can be stored in a closed container (a preserving jar works very well), undisturbed, in the fridge.

Refresh your starter daily:

Use 1 tsp starter culture and mix it with 1/4 cup water and 1/4 cup flour. Leave is out on the counter if you plan to bake with it on a regular basis. Repeat the feeding routine every 24 hours.
 You can also keep your starter culture in the fridge if you don’t plan to bake with it very often. If in the fridge, feed it once a week, and take care to keep the starter on the dry side, as the cool (fridge) temperatures promote the acid acids in the starter. Those can eventually make the starter too acidic.


I like to use a mix of white and whole grain wheat flours for the starter culture. Use whole grain rye flour if you plan on making rye breads. Freshly ground flour is the best, avoid old or bleached flours, loaded with add-ons. If you can’t mill it yourself, buy local flour in bulk, which is ofter the freshest. If possible, buy organic: Non-organic flour is almost always treated with fungicides which are known to affect the yeast development.


If tap water is treated with chlorine it will have a negative effect on the growth of beneficial bacteria in our starter. Spring water from a bottle is a good alternative; or just leave a jug of tap water standing out on the counter overnight and most of chlorine will evaporate.


  • Store starter in a glass jar or other container (glass is good, you like to see your culture)

  • When refreshing the starter, keep some space in the jar for expansion but try not to leave too

    much space to prevent mold from growing, especially when kept in the fridge in between


  • Starter cultures like temperatures around 75 F and may need more refreshments if kept in a

    warm environment

  • Never place a jar with starter culture in direct sun or on a stovetop/hot oven. Yeasts are killed

    around 140 F

  • Don’t put the starter culture in the freezer, yeast die when temperatures are below 32 F

  •  If your storage space is rather cold, use warmer water for refreshment (80 F)



A fully ripe starter culture is happily bubbling away in your glass jar, it will look vibrant, not collapsed and has a pleasant smell of sweet grain.... or not....
If a starter is too old (overripe) it may look slightly pale/gray, is rather flat on top, and it may even have a bit of grayish liquid floating around the edges. The odor may be strong vinegary and alcoholic. It may not look great but it’s mostly likely not dead.

If you can rule out the fatal contamination of mold or fungicides your starter can almost always be brought back to life! Most likely, the acids in the culture have taken over (cold temperature benefit that) and yeast growth has come to a stop. What is needed now is a good refreshment of a very small amount of starter culture with plenty of fresh flour and water to dilute the acid and provide new food for the yeasts and bacteria.

Use about 5 times the amount of flour and 7 times the amount of water on a teaspoon of starter culture to refresh a sluggish starter.

Remember that a starter culture should have the texture of wet concrete.



When you are ready to bake with your starter culture you will need to refresh it to make what is often called a “sourdough" or “production sourdough” in recipes. Any way it’s called, it is always the ripe or refreshed starter culture that’s ready to go into your bread.

Make as much sourdough as you need according to your recipe, but remember to start early enough to bring the culture to the right amount of sourdough needed. You often have to start 12-24 hours before the baking process with one or two feedings. 

Your starter is ready to go now!