What does raising the temperature to 170°F accomplish in the mash-out stage?

Raising the temperature to 170°F during the mash-out stage is primarily aimed at preserving fermentable sugars. This process involves denaturing enzymes in the mash that are responsible for breaking down starches into sugars, effectively stopping further conversion. By doing so, you ensure that the sugars present in the mash are retained for fermentation, maximizing potential alcohol yield in the finished beer. This step is crucial for maintaining the desired sugar profile, as it helps to stabilize the sugar concentration before lautering begins.

While the other options may have relevance in different contexts, they do not accurately describe the main goal of the mash-out process. Enhanced color extraction is more related to the choice of malts and the brewing technique rather than mash temperature specifically. Increasing bitterness relates more to hop addition during the boil rather than the mash-out stage. Reducing alcohol content is not a goal during any normal mashing process, particularly not at this stage, as raising the temperature is more about optimizing fermentable sugars rather than impacting the final alcohol level negatively.