According to Michael Ruhlman, "Ratio, The Simple Codes Behind the Craft of Everyday Cooking", page 6-7, a standard yeast to flour ratio is 2 1/4 ounces to 4 cups of flour. However, in actuality, 1/8th teaspoon or 1/4 gram will also raise the same amount of flour, it will just take a longer time. The more yeast used, the faster the rise.
What is the difference? The flavor developed is inversely proportional to the rise time, i.e. quick rise > low flavor, longer rise>more flavor.
Yeast, regardless of its form, is a biologic entity that thrives and reproduces when food (starches and sugars) and water are available. How fast it generates carbon dioxide depends on:
- how much yeast one starts with, and
- how much food and water are available, and
- what the temperature is (cooler > slower, warmer > faster
From what I've been able to learn, there is NO magic and precise answer. In fact, I do not use any additional yeast when making bread products using my 25 year old sourdough starter. Then again, it may take 24-72 hours to achieve the rise I'm looking for.
Using yeast as a rising agent is NOT the same as using chemical leveners such as baking soda or baking powder, the process is biologic, not chemical.
Originally Posted by kokopuffs
I don't know what you mean by the term "forgiving". All I want to know is how much SAF yeast is required to cause the dough to rise within the time frame set forth by the recipe - approx 90 minutes. And btw for the past 11 years since I embarked on breadbaking, I've used SAF Red exclusively and my bread is always made using a poolish, which is a kind of preferment and therefore I know a little something concerning dough and how to work it! 8^)