Light strike is a fault caused by exposure to which?

• A. UV/visible radiation
• B. Temperature fluctuations
• C. Oxygen exposure
• D. Microbial contamination

Answer: (A)

Exposure to light triggers a photochemical fault in wine. When wine, especially white and in lighter bottles, is exposed to UV and visible light, photosensitizers like riboflavin absorb energy and drive reactions that form volatile sulfur compounds. These compounds create the light-struck aromas described as sulfurous, sometimes reminiscent of burnt matches or wet cardboard. The problem happens quickly under bright artificial lighting or direct sunlight, and is mitigated by storing wine in dark, tinted containers or away from strong light.

Other factors listed cause different faults: temperature changes can lead to heat damage or accelerated aging, oxygen exposure leads to oxidation, and microbial contamination leads to spoilage notes.