I thought that yeast only grew on free sugars, such as in grapes to make wine. To grow on starches, one needed to first cook, then add a malt (enzymes) to convert the starch to free sugars, then add yeast. No? What is the yeast consuming as it grows?
Yeast is everywhere! It exists in the air around us all the time but can concentrate on the skins of grapes or other fruits. Yeast thrive on sugars of all kind, whether from wheat or malted barley or honey (and beyond!). What is important is that the yeast is fed in a proper regimen: always feed as much starter as you want equal parts by weight of flour/water: Example: weigh out 4oz of flour then add 4oz water and 4 oz flour. Then, once fed, the starter will take approximately 12 hours or so to go through the food if kept at room temperature. You should see the starter bubble and swell; when it starts to subside, that indicates the yeast are no longer feeding and are beginning to become inactive. This is where you will want to either feed them again OR begin baking! If the starter is kept in the fridge, it will go through the food in a week. I hope this helps! Kim@KAF Just to add to Kim's great info. here, Mike - yeast is able to convert the starch in flour into sugar on its own, without any help from malting. It's pretty self-sufficient, given the right atmosphere... PJH
March 19, 2013 at 1:10am