During which phase does yeast show active fermentation?

Yeast shows active fermentation during the attenuative phase. This phase occurs after the initial fermentation, when yeast begins to actively consume sugars and produce alcohol and carbon dioxide. During attenuation, yeast cells are highly active, converting the available fermentable sugars into ethanol and various fermentation byproducts.

This phase is characterized by a significant decrease in sugar concentration as the yeast continues to metabolize these sugars, leading to the production of alcohol, carbon dioxide, and other flavor compounds that contribute to the beer’s character. The length of this phase can vary depending on several factors, including yeast strain, temperature, and the specific gravity of the wort.

Other phases, such as flocculation and maturation, involve different processes. Flocculation is the process where yeast cells clump together and settle out of the fermentation broth, while maturation refers to the aging of the beer post-fermentation, allowing flavors to develop and unwanted compounds to settle. The adaptive phase involves yeast acclimating to the fermentation environment but does not represent the period of active fermentation.