Guide
Sugar, fat and air: the three levers
Once you know what each of the three does, you can adjust any recipe on purpose rather than by hope, and diagnose almost anything that goes wrong.
The short answer
Sugar keeps it soft and stops big ice crystals forming. Fat carries flavour and makes it feel creamy. Air makes it light enough to scoop and eat. Move one and you move the others: that is the whole craft.
Sugar: sweetness is the least of it
Sugar lowers the temperature at which a mixture freezes, so a sweeter base stays softer in the same freezer. It also gets physically in the way of water molecules trying to join up into crystals.
That is why sorbet recipes are so exacting about quantities: with no fat to help, sugar is doing the entire job alone.
- Rule of thumb: 130–170 g of sugar per litre of ice cream base; noticeably more for sorbet.
- Honey, golden syrup and glucose keep things softer still, gram for gram, than ordinary sugar.
- Alcohol does the same job even more strongly: a tablespoon per litre is plenty.
- Cut the sugar and you will get a harder, icier result, however good the dairy.
Fat: flavour and the feel of it
Fat coats the tongue, carries aromas that water cannot, and physically separates ice crystals so they read as smooth rather than gritty. It is the reason full-fat dairy makes such a difference.
Commercial categories are set by fat: economy tubs sit near the legal minimum, while “super-premium” is typically 14 to 18% butterfat with very little air. Most home recipes land in that upper range without trying, which is why homemade often tastes richer than shop-bought.
- More cream, less milk for a richer, denser scoop; reverse it for something lighter and closer to gelato.
- Egg yolks add fat too, plus an emulsifier that keeps everything stable.
- Dairy-free? Full-fat coconut milk and cashew cream have enough fat to behave similarly. Oat and almond milks do not.
Air: the one nobody mentions
Churning whips air into the mixture. The trade name for it is overrun, and it is measured as a percentage of the original volume: 100% overrun means the ice cream has doubled in size, so half of what you bought is air.
Industrial ice cream can be close to that. A home machine typically adds 20 to 30%, which is why a home-made litre feels so much heavier than a shop-bought one and why it tastes of more: there is simply more ice cream per spoon.
Some air is essential, though. Ice cream with none at all is unpleasantly hard and greasy, which is exactly what a no-churn mixture becomes if you fold the cream in too roughly.
- Do not overfill the machine: the mixture needs room to grow.
- Do not over-churn either. Past the soft-serve stage the fat can start to churn into butter.
- No-churn recipes get all their air from whipped cream, so keeping it during folding is the whole technique.
Adjusting a recipe on purpose
- Too hard straight from the freezer? Add sugar, swap some for honey or syrup, or add a tablespoon of alcohol.
- Icy and coarse? More fat, more sugar, colder base, faster freezing.
- Tastes flat? Usually salt rather than sugar. A good pinch sharpens everything.
- Too rich and cloying? More milk, less cream; or add acidity with lemon juice or buttermilk.
- Too sweet? Do not simply cut the sugar. Add salt and acid first, and only then reduce sugar, accepting a firmer result.
Put it into practice