DAIRY TECHNOLOGY: FROZEN DESSERTS
Diagram
Gelato and ice cream side by side
Gelato
An Italian frozen dessert: churned slowly, little air, less fat, served warmer, dense and silky.
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Ice cream
A frozen dessert churned faster with more air: lighter, colder, and scooped hard.
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The core difference
Air and temperature. Gelato holds less air and is served warmer, so it tastes denser and more intense.
Figure 1: Gelato compared with ice cream. Drawn in our own style from Chris Clarke, The Science of Ice Cream, Royal Society of Chemistry, 2007, and Morgan Morano, The Art of Making Gelato.
Introduction
Gelato and ice cream look alike in the tub, but they are built differently. Gelato is dense and silky; ice cream is light and fluffy. The difference is air, fat and serving temperature.
The core difference is overrun, the air beaten into the dessert. Gelato is churned slowly and holds about 20 to 35 percent air, so it is dense. Ice cream is churned faster and can hold up to 100 percent air, so it is light. Gelato is also served warmer, about minus 12 degrees C against about minus 18 degrees C for ice cream, so it melts faster on the tongue and its flavour comes through stronger.
Quick comparison
Table 1: Gelato compared with Ice Cream
| Aspect | Gelato | Ice Cream |
|---|---|---|
| Origin | Italy | Many countries, modern industrial dessert |
| Air (overrun) | Low, about 20 to 35 percent air | High, up to 100 percent air |
| Fat content | Lower, about 4 to 8 percent fat | Higher, about 10 to 16 percent fat |
| Churning speed | Slow, gentle churning | Faster churning that beats in air |
| Serving temperature | Warmer, about minus 12 degrees C | Colder, about minus 18 degrees C |
| Texture | Dense, silky, smooth | Light, fluffy, firm |
| Flavour | Intense, flavour comes through fast | Milder per spoonful, cold dulls flavour |
| Melting | Melts quickly on the tongue | Melts more slowly, holds its shape |
| Main base | More milk, less cream, sometimes no egg | More cream, often with egg yolk |
| Main use | Eaten fresh in small cups and cones | Scooped, sundaes, sandwiches and tubs |
Scientific explanation
Definition
Gelato is the Italian frozen dessert made from milk, sugar and flavourings, churned slowly with little air and served at a warmer temperature than ice cream.
Ice cream is a frozen dessert made from cream, milk, sugar and flavourings, churned with air beaten in and frozen hard for scooping.
Working principle
Churning works by freezing the mix while stirring it. Slow stirring makes small ice crystals and beats in little air, giving a dense silky body. Fast stirring beats in more air, which makes the dessert light and fluffy.
Serving temperature matters because cold dulls taste. Gelato served warmer melts faster on the tongue, so its flavour reaches the taste buds more strongly than the same flavour in colder ice cream.
Apparatus
A batch freezer or gelato machine that churns slowly and freezes the mix.
An ice cream freezer that churns faster and beats in air, plus a hardening room for ice cream.
Measurement procedure
For gelato, mix milk, sugar and flavourings, pasteurize the mix, cool it, churn it slowly in the batch freezer until it is thick, and serve it at about minus 12 degrees C.
For ice cream, mix cream, milk, sugar and flavourings, pasteurize and homogenize the mix, churn it with air beaten in, then harden it at about minus 18 degrees C or colder.
Factors affecting readings
The fat and sugar of the mix decide the texture: more fat gives a richer body, and sugar lowers the freezing point so the dessert stays scoopable.
The churning speed decides the air: faster churning gives more overrun and a lighter dessert. Storage temperature decides the serving: too cold and gelato turns hard like ice cream.
Formulas and calculations
Overrun is the air beaten into the dessert, worked out by weight: Overrun (percent) = ((Weight of mix minus weight of frozen dessert) divided by weight of frozen dessert) x 100, for the same volume.
Worked example: one litre of mix weighing 1.0 kg churned into one litre of gelato weighing 0.80 kg has an overrun of (1.0 minus 0.80) divided by 0.80, times 100, which is 25 percent. The same litre of mix churned into ice cream weighing 0.55 kg has an overrun of (1.0 minus 0.55) divided by 0.55, times 100, which is about 82 percent.
Industrial applications
- Gelato: fresh cups and cones in gelaterias, eaten the same day.
- Gelato: fruit and nut flavours where an intense taste is wanted.
- Ice cream: scoops, sundaes and ice cream sandwiches.
- Ice cream: tubs sold in shops for eating at home.
- Both: desserts, cakes and milkshakes, with the choice made on texture and flavour.
Advantages and limitations
- Gelato advantage: dense and silky, with intense flavour from the warmer serving temperature.
- Gelato limitation: melts fast and must be eaten fresh, and it is harder to store.
- Ice cream advantage: light, firm and easy to store and scoop, with a long shelf life.
- Ice cream limitation: colder and airier, so its flavour is milder per spoonful.
FAQ
Is gelato just Italian ice cream?
Nearly, but it is made differently: less fat, less air, slower churning, and served warmer, so it is denser and more intense.
Why is gelato served warmer?
At about minus 12 degrees C it melts faster on the tongue, so its flavour comes through stronger than ice cream at minus 18 degrees C.
Which has more fat?
Ice cream. It usually holds 10 to 16 percent fat, while gelato holds about 4 to 8 percent.
Why is ice cream fluffier?
It is churned faster and holds more air, up to 100 percent overrun, while gelato holds only about 20 to 35 percent air.
Can I store gelato like ice cream?
Not well. Kept at ice cream temperature it turns hard and loses its silky texture, so it is best eaten fresh.
References and further reading
- Chris Clarke, The Science of Ice Cream, Royal Society of Chemistry, 2007 (Google Books page read)
- Morgan Morano, The Art of Making Gelato, on slow churning, less air and warmer serving (Google Books page read)
- FTN books on disk: Ice Cream and Frozen Desserts (agrimoon dairy series).
