Why can airy ice cream melt slower even though it looks lighter?

Answer: Air cells insulate heat

Slower syrup drainage — Not quite. A thicker syrup phase can drain more slowly during meltdown, so viscosity does matter. But the clue in the stem is airy and lighter. The counterintuitive effect comes from trapped air cells interrupting heat transfer, not from syrup flow alone.

Air cells insulate heat ✓ — Right. Air cells interrupt heat flow, so high-overrun ice cream can begin melting more slowly than a denser one. That does not mean more air always means better ice cream: cheap high-overrun products can taste weak because part of the bite is literally air. The counterintuitive bit is that lightness and slower heat penetration can come from the same bubbles.

Fat network stiffens — Not quite. A fat network can help a scoop hold shape, but airiness points to a different mechanism. The trapped bubbles reduce heat penetration through the frozen foam. Fat structure and air structure cooperate in real ice cream, yet the lighter-looking sample can melt slower because air itself is a poor heat path.