But yeast is all around us and it's very easy to cultivate for your home baking needs.
There are many different methods but the simplest is to just mix flour and water in a 3:2 ratio by volume to a pit each day, and soon you'll have a bubbling mass known as a sourdough starter because of the aroma it gives off.
By the second or third day you should begin to see little bubbles forming in your mixture this is carbon dioxide that the yeast emits as the mixture ferments.
After five days of feeding my starter which I named Grow Dough Baggins we made a simple sourdough loaf.
Take 115g from the starter and add to a mixing bowl, replace this by feeding your starter with more flour and water in same ratio as before.
Feed your starter each time you use it and if you're not baking every day you can store it in a fridge where it will only need feeding once a week.
Add 389g of 00 grade bread flour to the mix along with 10g of salt.
Combine with 225ml of room temperature water and 25ml of oil, olive is traditional but we used rapeseed as we prefer the flavour.
Once the dough is formed lightly flour a suitable surface and knead the dough before returning to the bowl and covering to prove.
The time to rise will vary depending on environmental conditions but as the starter is not as rapid as commercially produced dry yeast it will take at least four hours.
Once its doubled in size again flour a suitable surface and gently knock it back and pla e into a baking tin, cover and prove again for another hour or two.
Pre heat an oven to 200°C (400°F) and bake for 35 to 40 minutes before removing and allowing to cool on a wire rack.
You can see a video of this on my YouTube here;
As always take care