Why does beer foam?
Show answer & explanation
Answer: CO2 nucleates on proteins
Yeast cells create bubbles — Wrong. Yeast did produce CO2 during fermentation, but foam forms when pouring because dissolved CO2 escapes, stabilized by proteins.
CO2 nucleates on proteins ✓ — Correct! Beer contains dissolved CO2 (from fermentation). When poured, pressure drops and CO2 forms bubbles. Beer proteins (from barley/wheat) and hop compounds coat bubble surfaces, stabilizing foam. Without protein, bubbles pop quickly like soda. That's why beer head lasts—it's protein-stabilized foam!
Sugar ferments when poured — Wrong. Fermentation happened during brewing. Foam forms because dissolved CO2 escapes when poured, creating protein-stabilized bubbles.
More Food & Nutrition questions
- Parmigiano Reggiano is made with milk, salt, and rennet only, so why can older pieces taste more savory or spicy without extra seasoning?
- Why does a Parmigiano Reggiano wheel wait until at least 12 months for the official selection mark instead of being fully approved when it is molded?
- How can Parmigiano Reggiano keep developing flavor after its starter bacteria have done their early acid-making job?
- A young Parmigiano Reggiano can taste milky, while older wheels lean nutty, spicy, or broth-like; what pushes the flavor away from plain dairy?
- Why does aging Parmigiano Reggiano from 12 months to 36 months not matter much for removing lactose?
- Why can older Parmigiano Reggiano turn crumblier and grainier instead of simply becoming a harder block?