In fact, air is an essential component of high-quality gelato. It plays a critical role in determining the texture, softness, appearance, and overall mouthfeel of the final product. Air gives gelato its smooth body and helps reduce the perception of cold on the palate—making it creamier and more pleasant to eat.
What Is Overrun?
Overrun occurs when air is whipped into the mix during freezing, as the liquid base begins to transition into a solid state. The amount of air incorporated depends on three main factors:
- The raw ingredients used: Some ingredients naturally support air incorporation (like skim milk powder or egg whites), while others inhibit it (such as fats and dense pastes).
- The recipe’s balance: A well-balanced mix ensures the right texture and proper overrun.
- The churning intensity: The speed and design of the batch freezer (or gelato machine) determine how much air is introduced.
Why Overrun Matters
A well-managed overrun results in gelato that is:
- Creamy and stable
- Easier to scoop and serve
- Visually appealing in the display case
- Less icy and more pleasant on the tongue
Too much air can lead to a product that feels hollow and melts too quickly. Too little air, on the other hand, can result in an overly dense or icy gelato.
How to Calculate Overrun
The amount of air incorporated in gelato can be measured using a simple formula:
Overrun (%) =
(Weight of the mix – Weight of the gelato) / Weight of the gelato × 100
For example:
- If your original mix weighs 1,000g and the resulting gelato weighs 750g, the overrun is:
(1000 – 750) / 750 × 100 = 33.3%
Ideal Overrun Values
The ideal overrun varies depending on the type of gelato:
- Milk-based gelato (with cream and egg yolk): 35–40%
- Fruit-based gelato (sorbetto): 25–30%
These values ensure a creamy yet full-bodied texture while preserving flavor integrity and structural stability.
Common Mistakes and Tips
Some gelato makers might be tempted to use egg whites to artificially increase overrun, but this practice is not recommended for two reasons:
- Hygiene and food safety: Raw egg whites can pose a risk of contamination.
- Structural instability: Gelato made this way tends to deflate quickly in the showcase.
If a gelatiere wishes to create a denser, more compact, and flavorful product with less air, a practical trick is to overload the batch freezer slightly. This reduces the volume of air in the chamber, automatically limiting the amount incorporated into the mixture. However, this must be done carefully to avoid freezing inefficiencies or texture issues.
Ingredients and Conditions That Affect Overrun
Ingredients that enhance air incorporation:
- Egg yolks and egg whites
- Skimmed milk powder
- Some mineral salts
- Well-dosed stabilizers
Technical conditions that support overrun:
- Proper mix aging/maturation
- Freezer loading at temperatures below +4°C
- Adequate churning speed
Factors that inhibit overrun:
- High fat content
- High sugar concentration
- Cocoa or dense flavor pastes
- Insufficient mix maturation
- Low agitation
- Overfilled batch freezer
Final Thoughts
Overrun is not about deception—it's about technique, balance, and quality. Mastering the role of air in gelato production is essential to producing a product that is both delicious and technically refined. Each recipe and machine setup may behave differently, so small tests and adjustments are key to finding the perfect texture and overrun for your unique gelato style.