yeast cakes or ¼ pound yeast

Yeast cakes are compressed blocks of fresh baker's yeast (Saccharomyces cerevisiae), a single-celled fungus cultivated and stabilized for use in leavening baked goods and fermented beverages. Historically the predominant form of commercial yeast before the widespread adoption of active dry yeast in the mid-20th century, yeast cakes contain approximately 70% moisture and are formed by pressing and molding freshly grown yeast cells into compact blocks or squares weighing typically 0.6 ounces (approximately 17 grams) per cake.

Fresh yeast cakes possess a pale tan to beige color, a slightly grainy texture, and a distinctive earthy, slightly alcoholic aroma. The living cells remain metabolically active, making them highly perishable and requiring refrigeration. Modern yeast cakes, also called fresh yeast or compressed yeast, maintain similar potency to their historical predecessors but with improved consistency and extended shelf life through controlled moisture management.

Yeast cakes serve as a leavening agent in bread baking, pastry production, and fermented beverage preparation across European, North American, and global cuisines. They are dissolved or crumbled into liquid to activate fermentation, typically used in proportions of one cake (approximately 0.6 ounces or 17 grams) per pound of flour in bread doughs. The slower, more gradual fermentation compared to instant yeast makes them preferred in enriched doughs (brioche, panettone) and traditional sourdough methods where extended bulk fermentation develops complex flavors.

Bakers often prefer fresh yeast cakes for their reliability, extended fermentation window, and the depth of flavor they impart to final products. They require slightly warmer activation temperatures than dry yeast and are especially valued in European artisanal baking traditions and institutional bakeries.