Why does cheese have holes?
Show answer & explanation
Answer: Bacteria produce carbon dioxide
Bacteria produce carbon dioxide ✓ — Correct! Swiss cheese holes (eyes) form from Propionibacterium freudenreichii bacteria added during cheese-making. These bacteria consume lactic acid and produce carbon dioxide gas. As cheese ages, CO2 bubbles get trapped in the elastic curd, forming holes. More bacteria = more holes. Modern clean milk produces fewer holes (less hay dust for bubbles to nucleate on)!
Mold eats passages through cheese — Wrong. Mold grows on cheese surfaces (like blue cheese veins), but Swiss cheese holes are gas bubbles from bacterial CO2 production.
Cheese shrinks leaving gaps — Wrong. Cheese doesn't shrink enough to create large holes. Holes are CO2 gas pockets from bacterial fermentation.