Does dry yeast require more or less oxygen compared to liquid yeast?

Dry yeast generally requires less oxygen compared to liquid yeast. This is primarily due to its preservation method; dry yeast is dehydrated and, as such, is less metabolically active until rehydrated. When dry yeast is rehydrated, it can utilize the nutrients available in the wort more efficiently in anaerobic conditions, producing alcohol and carbon dioxide with minimal oxygen necessary for its activation.

Liquid yeast, on the other hand, is in a more active, nutrient-rich state which can consume oxygen more readily as it begins fermentation and relies on aerobic respiration initially for energy production before shifting to anaerobic fermentation as the oxygen levels decrease. Therefore, the oxygen requirements for dry yeast are typically lower, as it relies more on its recovery from the dormant state rather than aerobic processes.

Strain variation may affect specific needs, but the general trend stands that dry yeast does not require as much oxygen as liquid yeast, making it a more suitable choice for certain brewing practices where lower oxygen levels can be advantageous.