What is overrun?
The single technical concept that explains why a scoop of Italian gelato tastes so much more intense — and dense — than a supermarket tub of ice cream.
The definition
Overrun is the food-science term for the volume of air that is churned into a frozen dessert during production, expressed as a percentage of the original liquid mix.
The formula is straightforward:
Overrun (%) = [(Volume out − Volume in) ÷ Volume in] × 100
A mix with 100% overrun has doubled in volume — half the final product is pure air. A mix with 25% overrun has grown by only a quarter — the product remains dense and ingredient-rich.
Industrial ice cream: selling you air
Commercial ice cream producers typically operate at 80 – 100% overrun. Some mass-market brands push beyond 100%, meaning more than half the tub is air. This is not an accident — it is a deliberate economic choice.
High overrun reduces raw material costs dramatically. A litre of base mix becomes two litres of finished product. High-speed continuous freezers, stabilisers and emulsifiers make this possible at industrial scale. The result is a product that is light, airy, and fast to melt — engineered to feel satisfying on the first bite, but lacking depth.
The fat content of industrial ice cream (minimum 10% butterfat under UK law) also plays a role: fat is an excellent foam stabiliser, helping trap and hold air bubbles so the inflated structure persists on the shelf.
Artisan Italian gelato: density by design
Traditional Italian gelato is churned at 20 – 35% overrun — roughly a third of the air in a standard ice cream. The lower fat content of gelato (typically 4 – 8%) means there is less capacity to trap air anyway, but the slow-churn machines used in artisan production are also deliberately designed to minimise aeration.
The result is a denser, heavier product. A portion of gelato weighs significantly more than the same visual volume of ice cream. That density translates directly into flavour intensity: there is simply more ingredient per gram.
Gelato is also served at a slightly warmer temperature (around −10 °C vs −18 °C for ice cream). This softer, pliable texture is in part a consequence of the lower overrun — without air as an insulating buffer, it responds more readily to warmth, releasing aromatics more quickly on the palate.
Side by side
| Property | Italian Gelato | Industrial Ice Cream |
|---|---|---|
| Overrun | 20 – 35% | 80 – 100%+ |
| Fat content | 4 – 8% | 10 – 18% |
| Serving temperature | −10 °C | −18 °C |
| Air by volume | ~25% | ~50%+ |
| Flavour intensity | Very high | Moderate |
| Melt speed | Fast | Slow |
| Texture | Dense & silky | Light & fluffy |
| Shelf life | Days – weeks | Months – years |
Why it matters for the consumer
When you pay for a scoop of gelato at a proper gelateria, you are paying for a product that is 65–75% actual ingredients — milk, cream, sugar, pistachio paste, fresh fruit — and only 25–35% air. A tub of supermarket ice cream, by contrast, may be 50% or more air by volume.
This is not an abstract distinction. It is why a small cup of genuine gelato leaves you more satisfied than a larger serving of ice cream, and why the pistachio or hazelnut flavour lingers on the palate rather than dissolving into an anonymous sweetness.
"Less air means more of everything else. That is the entire philosophy."
— Gelatone, Covent Garden