Why is a ferulic acid rest performed during mashing?

A ferulic acid rest during mashing is primarily performed to increase the phenolic character of the beer. This rest typically takes place at a temperature range of around 110-115°F (43-46°C), which promotes the activity of specific enzymes, particularly ferulic acid decarboxylase. This enzyme helps convert ferulic acid, which is naturally occurring in certain malted grains, into 4-vinyl guaiacol, a compound that contributes clove-like aromas and flavors to the beer, particularly in Weizen-style beers like Hefeweizen.

The other choices relate to common goals in the brewing process but do not directly correlate with the specific benefits of a ferulic acid rest. Although improving sugar extraction, enhancing yeast viability, and reducing diacetyl formation are critical parts of brewing, they are not the primary objectives associated with performing a ferulic acid rest. Hence, the focus on enhancing the phenolic character makes this option the correct choice.