Ingredients:

1 1/2 cup (200 grams – 8 ounces) bread flour or all-purpose flour sifted
1/2 cup (90/100 grams – 3.5/4 ounces) spring water (45%-50% of flour weight)
1 tbsp honey
do not use tap water because the chlorine contained in it will kill microorganisms, thus preventing yeast from being created.

INSTRUCTIONS:
Mix all the ingredient to form a soft, smooth and no-sticky dough (like pizza dough). If it’s too sticky add a little flour otherwise add more water.
Shape the dough into a ball and place in a glass bowl (do not use metal, wood or plastic bowl to avoid materials contamination, use just a glass one).
Cover with the lid or a plate (do not seal up, just put it on with no pressure), the dough has to breath but not dry out.

Let it rest in a warm place (75-77°F/24-25°C) for 48 hours (usually in my house it’s 68°F/20°C so I pre-heated oven to 100°F/38°C, switched it off and turned the light just for few hours – in summer you can leave it at room temperature).
If you put the dough in the oven, put inside some ripe fruit (I prefer an apple, that also gives good aroma to the dough). This is important to give the dough a lot of yeasts to help the rising process. But if you’ve just baked something you can skip this passage because the air has still a lots of new yeasts.

After 2 days the dough should be rose and full of little air bubbles, if so congratulation, your mother yeast is born!

(If nothing occurs, refresh it as written below, let rest in a warm place for 48 hours and if nothing happens you have to throw it away – try to read this recipe very carefully and repeat the procedure step by step, don’t give up! – slow and steady wins the race!)

Refresh as written below, put it in a glass jar, close it, put in the refrigerator or leave at room temperature.

How to refresh Mother Yeast

If refrigerated, keep mother yeast at room temperature for about 2 hours.
Preheat oven to 100°F-38°C (you can skip that passage if your room temperature is high enough).
Take a piece of mother yeast (1/2 cup – 100 grams – 4 ounces) and put it in a bowl.
Add 45%-50% of water (less than 1/4 cup – 45/50 grams – 1.5/2 ounces) and keep in mind to change water temperature at every refresh you do, first warm next time cold and so on… it helps balance acidity.

Stir until dough is quite melted.

Add flour (all-purpose or bread flour) in the same weight of the piece of mother yeast (3/4 cup -100 grams – 4 ounces) and form the new dough (it has to be soft, smooth and no sticky, help you with more flour or water to adjust).

..

Put it in a jar glass, place the lid on but do not close it (let it breath).

Switch off the oven and leave the light on.
Put inside the oven some ripe fruit (ex. apple).

Put the jar with mother yeast inside the oven and:

  • if your mother yeast has less than 6 months, let rest 3 hours, then pull out the jar and leave 1 hour at room temperature;
  • if your mother yeast has more than 6 months, let rest 1 1/2 hours, then pull out the jar (even if it’s not triple).

Close the jar, put in the refrigerator or leave at room temperature.

How often do you have to refresh it?

  • If you keep it at room temperature (65°/77°F-18°/25°C) you have to refresh it every 2 days
  • If you keep it in the fridge (40°/43°F-4°/6°C) you have to refresh it every 5-7 days
  • If you make a big batch over 1.8 lb-800 grams you can refresh it even after 10 days
    Useful and important info to know

    Keep in mind that before you can use mother yeast to make recipes you have to wait at least one month to obtain some good results, in the mean time you can mix unused mother yeast in dough using a buy yeast to make your bread.

    After 6 refreshing months your yeast will be stabilized and the final products will taste and look better.
    During this 6 months yeast could be too much acidic (you can smell it), so you can balance it by putting a very little pinch of salt and mix it.

    That’s all!

    GREAT INFO AND RECIPE from: http://www.ilariasperfectrecipes.com/mother-yeast-recipe/