Air enters during batch freezing and is measured as overrun: how much the volume of the mix increases. Proteins and fat keep the bubbles stable. Air insulates, so the gelato feels less cold, and it decides whether the texture is light or dense.
Gelato works with low overrun, usually 25–35%, which is why it is dense and intensely flavoured. Industrial ice cream often reaches 80–150%: more volume per kilo of mix, but less flavour in every spoonful.
| Type | Overrun ~% | Notes |
|---|---|---|
| Custard gelato | 25–35 | Dense, served with a spatula |
| Fior di latte | 25–35 | Proteins hold the air |
| Chocolate | 20–30 | Dense, rich base |
| Fruit sorbetto | 15–25 | No fat, holds little air |
| Soft serve | 35–90 | Soft, from a soft-serve machine |
| Semifreddo | 80–100 | Air comes from whipped cream |
| Industrial ice cream | 80–150 | Cheap products reach up to 200 |