The phytase enzymes can be released either by long fermentation or by soaking the flour which means adding water and letting it sit before adding yeast. Sour dough starters already have the phytase enzymes released. So it jump starts the process when added to a dough with new flour.

I used to use sour dough starter, but was finding that a good amount of my flour was being used to feed it rather than being used in bread. When I converted my starter to whole wheat, it turned black after a few days. At this point, I threw it out, and started using instant yeast instead. Using the long fermentation method, I use only 1 tsp. of yeast for a triple batch of bread dough. Since I switched to the commercial yeast, I consistently get good rises and oven spring. When using the sour dough starter, consistency depended on catching the starter at its peak of activity.

In addition, I don’t really like the sour taste of sour dough. By using yeast, I like my breads much more, and my flour is used exclusively for breadmaking.

The time need for fermentation of sour dough bread is dependent on the activity of your starter and the temperature in your house. Sometimes a good fermentation can take as long as 18 hours or more. Whatever time it takes, it should be about double in size.