What is the first step in the proper growler filling procedure?

The first step in the proper growler filling procedure is to pre-rinse the growler with cold water. This is essential for several reasons. First, it helps to clean the interior surface of the growler, removing any residual contaminants or previous beer that could affect the flavor of the new beer being filled. Second, pre-rinsing cools the growler to the appropriate temperature, which is important because filling a growler with cold beer into a warmer vessel can cause excessive foaming. This step ensures that the growler is in optimal condition to receive the fresh beer, minimizing oxidation and contamination, and maintaining the integrity and quality of the beverage.

Considering the context, labeling the growler, inserting a tube to fill from the top down, and closing the tap after filling are important steps in the overall process, but they are not the initial actions necessary to ensure a clean and effective fill. Hence, pre-rinsing is foundational to achieving a successful growler filling experience.