What isa pellicle and what does it do?

A pellicle is a thin film or layer that can form on the surface of liquids, often seen in brewing and fermentation processes. It acts as a protective barrier, helping to prevent contamination by microorganisms and maintaining the integrity of the liquid beneath. In the context of brewing, a pellicle can also indicate the presence of certain yeast or bacteria, contributing to the development of flavors in sour beers. Overall, it plays a crucial role in the fermentation process and the overall quality of the beverage.