Convert between yeast types for any recipe.
The three common baking yeasts are all Saccharomyces cerevisiae but processed differently. Fresh (cake/compressed) yeast: 70% moisture, most perishable (2 weeks refrigerated), mildest flavor, traditional European baking. Active dry yeast: dehydrated granules with a dormant outer layer — must be proofed (dissolved) in warm water (105-110°F) for 5-10 minutes before use to activate. Instant (rapid-rise) yeast: finer granules, no proofing needed — mix directly into flour. Conversion ratios: fresh × 0.4 = active dry × 0.8 = instant. Or: 1g instant = 1.25g active dry = 3g fresh. One standard packet (7g/2¼ tsp) of instant yeast is designed for 3-4 cups (375-500g) of flour. Store opened yeast in the freezer for up to 6 months — cold doesn't kill yeast, it just slows it down. Test viability: dissolve in warm water with a pinch of sugar; it should foam within 10 minutes.