Which process involves the addition of substances like egg whites to clarify wine?

The process that involves the addition of substances like egg whites to clarify wine is known as fining. Fining serves to improve the clarity and stability of wine by removing suspended particles that can cause cloudiness. Egg whites, as well as other agents such as gelatin or bentonite clay, are used to bind with these particles, which then settle to the bottom of the fermentation vessel before the wine is filtered and bottled. This practice allows for a clearer, more visually appealing final product and can also have some influence on the wine's flavor and texture, depending on the fining agent used.

The other processes mentioned do not specifically involve the addition of clarifying agents. Filtering is a mechanical process that physically removes particles from wine without the use of fining agents. Barrel aging involves storing wine in wooden barrels to impart flavors and influences from the wood but does not clarify the wine. Natural stabilization refers to processes that allow wine to maintain its stability and quality over time without intervention, typically focusing on temperature control and proper handling rather than clarifying agents.