Fresh Yeast vs. Instant Yeast
It is common at our school to encounter the opinion that fresh yeast is superior to dry yeast. One baker even told us that when he switched from dry yeast to fresh yeast, the flavor of his bread improved. We would like to dispel the myth that fresh yeast produces better bread than dry yeast. In fact-if used properly-dry yeast will produce the exact same bread as fresh yeast. As long as the amounts are correct, the process is the same. It may even be the better choice in some situations, especially when you do not have a reliable source for fresh yeast. And, even if you do, instant yeast is a good back-up to have on hand in case you run out of fresh yeast. An unopened package of instant yeast has a shelf life of up to two years.
Active dry can be used at 50% of the weight of fresh yeast and instant dry can be used at 40% of the weight of fresh. Based on the recommendation of the yeast manufacturers, most people are under the impression that 33% is the proper conversion for instant yeast. This is true for an industrial process, but 40% is better in the artisan process, when dough temperatures are generally lower.
The instant form is the easiest to use since it does not need to be re-hydrated before adding to the dough. The only precaution is that it should not come in direct contact with cold temperatures and therefore should be mixed into the flour before adding water or added after the flour and water is incorporated.