Sourdough Basics

Sourdough is the oldest form of leavened bread, and was probably created by accident when dough was left out and wild yeasts and bacteria from the grain and air arrived and developed an airier, more delicious loaf.


There is evidence of sourdough in Ancient Egyptian archaeological digs, and it was shared by many cultures until modern baker’s yeast came onto the scene around 150 years ago.

Sourdough bread is created by by lactobacillus and wild yeasts fermentation the flour (present in the flour and the environment).


Amylase, an enzyme in wheat, activates In water and starts to break down starches into sugars, which the bacteria and yeasts metabolize, creating gasses.


Today baking sourdough has a cult following and many recipes and ideas can be found online and in print and with baker’s yeast running short during the COVID lockdowns, many people started baking sourdough obsessively, invigorating this age old method of bread making.



A healthy bread

It seems Most scientists and nutritionists are in agreement – naturally-fermented sourdough is a healthier than ‘regular’ bread made with commercial yeast:

  • It’s more nutritious, containing higher levels of vitamins, minerals and antioxidants. It also has lower levels of phytate, which means that your body can absorb all those nutrients more easily than ‘regular’ bread.
  • It contains less gluten than other bread, meaning, as I understand it, that even those on a gluten restricted diet can eat some sourdough without ill effect. 
  • Fermentation increases the bread’s resistant starch level, and resistant starches are really beneficial to your health too (exactly why and how, I’m still researching.)
  • Because sourdough contains prebiotics, it means it helps feed the good bacteria in your gut, making it easier to digest.
  • It has a lower glycaemic index, making it an ideal choice for people with diabetes.


It all starts with a starter. I followed King Arthur flour instructions on making  a sourdough starter (but rounded down the weight to an even 100g)

Day 0: In a wide necked large jar (1 liter glass fermenting or preserving jars are perfect) add 100g flour to 100g water and mix well until no dry flour remains. Cover with netting/muslin/cheesecloth and leave for 24 hrs

Day 1 – Day 5: Discard half to ¾ of the mix and add another 100g water and 100g flour and mix well. Keep covered.


By day 5 or even as long as day 9, you should see some bubbles forming and smell a pleasant yeasty sourness.


Test the starter – take a tablespoonful and drop it into a jar of water. If the starter floats, it is mature.


Note: Not all starters float that well and my friend who is a sourdough/fermentation enthusiast says her starters never really float. If there’s lots of active bubbles and it smells good, you are probably good to go.

A note on the flour and the water

Like everything in life, the better the quality of the inputs, the better the quality of the end product. 

  • Use filtered not chlorinated water. 
  • Use high grade bread flour not cake flour. This is generally not such a big thing in New Zealand as we don’t have cake flour as such and the protein levels between our high grade (strong) flour and standard flour is marginal.
    If you have access to good organic stone-ground flour, those are exceptionally good to use.

Yes, you can bake sourdough with other flours too – whatever you start your started with though, remain true to the type of flour (and even brand if you can) to feed it. Although, if you find it is slow going, my fermentation-enthusiast friend suggests feeding the starter with a bit of rye – apparently the yeasts and bacteria really love a bit of rye.

You can bake sourdough bread with different flours even if your starter is from white bread flour (see Sourdough with Levian in a later post).

Keeping an active colony of bacteria and yeasts

Yes, your sourdough starter is actually a scoby too (S-symbiotic C-colony O-of B-bacteria and Y-yeasts), just like a kombucha scoby. These fermentation colonies go by many names – often named SCOBY in reference to kombucha brewing, and “mother” when you talk about making brewed vinegar, “bug” when you do a ginger beer, and simply “starter” for sourdough baking. Whatever you decide to call it, this colony of bacteria and yeast needs regular feeding of flour+water to replenish the sugars already metabolized.

Keep feeding your starter daily , discarding half to ¾ and adding a mix of 100g flour and 100g water.

If you are regularly baking, your “discard” becomes the bit of the starter that you use in your bread.

Because keeping the sourdough well fed is almost like having a new pet to look after, a lot of people, for fun, name their sourdough starters. My main starter is named Gertie (Gertrude), and I’ve also got another one going named Penelope.

Discard or redistribution

Want not, waste not. When you have a nice active ferment going but you’re not baking bread, you can use your discard for various other baking projects – my favourite is sourdough pikelets. I normally keep a discard tub in the fridge and add to that each time I feed my sourdough, but don’t bake with it, until I have a good cup of “discarded” starter and then bake pikelets with that (recipe to follow).

How long can you keep a starter?

Indefinitely if you keep feeding it. According to the internet the oldest heirloom starter still alive was created in 1847.
Some scientists believe that because of the natural life cycle of the starter, you’re not really housing the same bacteria and yeasts perpetually, but often incorporate new yeasts and bacteria when you feed the starter, so what you end up with is not necessarily the descendants of what you started off with. I’ve not looked too much into the exact science… I like the romance of the idea of keeping an heirloom starter. 


Resting a starter

Taking a break from baking is easy – just pop your starter into the refrigerator, slowing down down metabolism of the yeasts and bacteria.

When you want to use your starter again, take it out, bring it to room temperature and give it a good feed (maybe two), before using it again.


Tasting notes

Just like wines that differ in their taste because of the region that the grapes where grown and how they were fermented, you can apparently taste the difference in where a sourdough starter was created. I’ve not personally tested this, but connoisseurs reckon a sourdough from the Black Forest in Germany will taste different to a sourdough started in Texas in America. It’s not only the local yeasts that impart this flavour, but also has to do with the local flour available.

Baking the bread

Direct Starter Method 

  1. Feed starter 4-12 hours before baking, so it’s good and bubbly.

  2. Mix your starter with water
    In a bowl mix some of your starter with water. The total weight of the water + starter should be around 400g, and we work with a starter ratio of 15-25% of the total weight of the flour you are going to add, so for adding 500g flour, your starter weight to add will be 75g – 125g, and you make up the rest (up to 400g) with water.

    I generally use 100g starter + 300g water

  3. Add 25g olive oil and whisk all the ingredients together before adding the flour.
    You can make sourdough without oil, but adding the oil results in a softer crust and crumb – definitely desirable over sometimes chewy and tough sourdough made without oils.

  4. Add 500g flour.
    Use a spoon or a fork to mix the flour through the wet ingredients until shaggy ribbons form and then gently work through with wet hands (keep it shaggy and tattery, just use your hands to get the last bit of flour worked into the rest of the dough).

  5. Autolyze
    Autolyze is the initial resting period after mixing flour and starter together and it is essential to create extensibility (ability of the dough to stretch without breaking) and elasticity (the resistance or pull back of the dough when stretched) – both which ensures a stronger bread.

    Leave the shaggy mix, covered with a wet tea towel or plastic wrap, for a wee while – 30 minutes to an hour.

  6. Sprinkle over 10g of fine salt. Work it into the dough with your hands and make a tight ball of dough. Let rest for 15 minutes
    Some bakers add the salt in with the water in step 2, and says it doesn’t affect their end product, but I tend to go the traditional route of keeping the salt out for the autolyze.
    You can bake sourdough without salt, but …yuck.

  7. Stretch and fold
    The stretch and fold stage is optional, but does result in a much nicer bread, so if you have the time and want to do the little bit of effort, it is well worth it.

    Take your ball of dough and stretch half of it upwards and away from you (to the North) – it should create a broad ribbon, fold the ribbon back over toward you (to the South).
    Repeat this step, going clockwise around, stretching East and folding back over to the West, then stretching out to the South and folding back up toward the North, then stretching out toward the West and folding back toward the East.

    One set of stretch and fold is four folds (North-East-South-West)

    Rest the dough for 15 minutes to 30 minutes.

    Repeat the North-East-South-West stretch and fold another 4-6 times, resting 15 minutes to 30 minutes between each set.

  8. Double up (bulk ferment)
    Rest your dough until it has doubled in size (covered with a damp tea towel or plastic wrap so it does not dry out and create crusty bits)

  9. Tighten and shape
    After the bulking up ferment, take your dough from the bowl and work it into a tight ball by pinching and folding dough from the top to the bottom.

    Sprinkle fine corn flour or rice flour over the ball and wrap tight in corn/rice flour dusted cloth or place into a proofing basket to do the cold ferment.

  10. Cold ferment
    Now your dough is ready to develop some more. If you have a cold kitchen, you can do this right on your benchtop, else in the heat of summer you can leave your dough in the fridge to rise.

    I generally work my schedule so that the dough is ready to do the long cold ferment overnight.

    Remember to keep the dough covered with a dusted tea towel or plastic wrap.

    Shortest for cold ferment is about 5hrs, but no longer than 36hrs.

  11. Score a design
    When ready to bake, score your bread if you want with a very sharp blade (lame) – you can get really fancy with designs. This helps the bread to “split” in a good way and not just burst open when it is baking. It looks pretty too!

  12. Baking
    Oven baked sourdough bread is normally baked in a cast iron pot, or Dutch oven. It needs to have a well fitted lid. Both the lid and the pot that you are going to bake in should be oven proof to about 240C.
    Long before you are to bake your sourdough, preheat your oven to 240C, and place your pot in the oven to heat up too.

    Handle your dough very carefully after the cold ferment so that you maintain all the lovely bubbles created.

    Place your dough into the hot pot (BE VERY CAREFUL TO NOT BURN YOURSELF), put the lid on top and put back in the oven to bake for 30 minutes.

    After 30 minutes, remove the lid, and turn the temperature down to 210C and bake for another 15-20 minutes (bread sounds hollow when knocked on).

  13. Cool and enjoy
    Remove pot from the oven and as soon as you can, the bread from the pot to cool.

    Tempted as you may be to have warm sourdough with melted butter straight from the oven, sourdough is really best eaten after it has rested for at least an hour (preferably even more) before you cut into it.

Adding flavours

Your imagination is your only limit. And your palate. When adding in flavourings or solids, never add more than 20% of your total dough volume.


  • Adding liquid flavouring can be done when you mix your starter with water and oil in the beginning (e.g. adding honey)
  • Adding solid flavouring can be done in round 2 or 3 of your stretch and fold sets (e.g. adding sliced olives)

Some delicious add-in flavouring that I’ve done before:

  • Rosemary and Sea Salt
  • Honey and Oats
  • Jalapeno and Cheddar
  • Black Olives
  • Sundried Tomato and Feta
  • Roasted Garlic and Herbs
  • Curry


  1. How do you measure 100g of water please

    1. Hi Irene, my little electronic kitchen scale measures in grams, so I put a jug on it, zero it out and pour water until it reads 100g. But water is easy – each ml weighs a gram, making conversion between grams and milliliters straightforward. 100ml = 100g

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