Volatile acidity (VA) in wine is primarily caused by which factors?

• A. Acetobacter bacteria and oxygen exposure
• B. Yeast metabolism during fermentation
• C. Acetobacter bacteria, poor sanitation, and oxygen exposure
• D. Temperature fluctuations

Answer: (C)

Volatile acidity in wine comes from acetic acid produced by acetic acid bacteria when ethanol is exposed to oxygen. Oxygen exposure allows these bacteria to oxidize ethanol to acetic acid, and poor sanitation increases the likelihood of bacterial contamination, raising VA levels. The combination of Acetobacter, oxygen, and inadequate cleaning and sanitizing creates the conditions for VA to rise, which is why this option is the most accurate. While yeast metabolism can generate small amounts of VA-related compounds and temperature can influence microbial activity, they are not the primary drivers of VA like the presence of Acetobacter with oxygen and poor sanitation.