Here are points to keep in mind when making sourdough starter from scratch:
When making starter, your goal is to harness the power of wild yeast in your environment. As there are abundant populations of yeast on the skins of some organic fruit and vegetables—grapes, for example—many recipes for making starter include them in the process. We will not use anything other than flour and water, however, because that is all we need.
A warm kitchen is bliss for a developing starter. The optimal room temperature for cultivating starter is 70-75 degrees, so begin your starter at a time of year when this temperature will be easy and economical for you to maintain, both day and night. Winter is not ideal; neither are the very hot days of summer, those over 85 degrees, if you are without air conditioning.
During the initial creation phase, you will feed your starter once each day, at approximately 24-hour intervals. Be sure to pick a time that will allow you to be relatively consistent in your feedings. For example, feed your starter every day before breakfast.
Use filtered water at room temperature for making starter. Bottled water also works, but tap water may fail to give consistently good results.
Use a container that provides room for your starter to double in volume; it should ideally be a container you can see through. I use a glass canning jar, which allows me to see the starter and to measure its growth (height) using the lines on the jar.
Dishwashing soap may leave a residue that can harm your starter’s growing microorganisms. You can avoid this by rinsing the jar and utensils with baking soda and water after washing to remove any soapy residue.
Be sure the lid fits loosely. You will need to cover the developing starter to get good results, but gas will form and with a tight-fitting lid the container could burst open. Plastic wrap and a rubber band work. I use either a metal or plastic canning lid, which I screw on loosely to prevent the jar from becoming air tight.
Every day you will discard half your starter. It feels wasteful, but you must get used to doing this because the health and vitality of your starter will forever depend upon your willingness to take this step.
Copyright, Ellen Arian, Ellen’s Food & Soul