Under stress conditions, do yeast form more or less esters?

When yeast are under stress conditions, such as high temperatures, nutrient limitations, or increased osmotic pressure, they tend to produce more esters. This is primarily due to the strain on cellular metabolism and increased fermentation activity, which leads to a higher production of byproducts, including esters.

Esters are formed through the reaction of alcohols and acids, and during stress, yeast often produce higher levels of fatty acids and higher alcohols, which can then combine to form esters. The increased metabolic activity in an environment where yeast are stressed often results in a complex array of flavor compounds, adding fruity and floral notes to the beer.

Understanding this biochemical response to stress in yeast is crucial for brewers, as the type and concentration of esters can significantly impact the flavor profile of the final product.