Frozen Yogurt in a KitchenAid Ice Cream Maker

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Frozen yogurt comes out icy for a reason that ice cream does not have: water with nothing to hold it.

Ice cream is roughly 35% fat, and that fat physically gets in the way of water molecules finding each other and forming large crystals. Yogurt has a fraction of the fat and considerably more water, so the crystals grow big and you get something closer to a sorbet with a sour note.

Two fixes, and both are worth doing.

Strain the yogurt

Line a sieve with muslin or kitchen paper, put the yogurt in, and refrigerate for 4 hours. A kilo of yogurt will give up a surprising amount of whey.

What is left is thicker, higher in fat and protein per gram, and much lower in free water. That alone transforms the texture.

Greek yogurt is already partly strained, which is why it works better than plain yogurt. Straining Greek yogurt further works better still.

Sugar is antifreeze, not just sweetener

Sugar lowers the freezing point of water. The more dissolved sugar, the smaller the ice crystals that form and the softer the finished result.

This is why a low-sugar frozen yogurt is rock hard. If you cut the sugar, you get ice, and there is no way around it with sugar alone.

A tablespoon of vodka or corn syrup helps if you want it less sweet. Alcohol does not freeze at domestic temperatures and interferes with crystal formation; corn syrup is an invert sugar that does the same job.

The bowl needs 24 hours

The KitchenAid attachment is a double-walled bowl with liquid between the walls, and it has to be frozen solid — 24 hours, at the back of the freezer, not overnight in a full freezer door.

A partly frozen bowl churns for forty minutes and produces a milkshake. This is the most common complaint about these attachments and it is nearly always the bowl.

Shake it. If you hear liquid moving, it is not ready.

Everything goes in cold

Room-temperature mixture into a frozen bowl wastes a large share of the bowl's cold budget just getting the mix down to freezing point. The bowl only holds so much.

Chill the mixture for at least 4 hours before churning.

What you need

• 1 kg full-fat Greek yogurt
• 200 g caster sugar
• 120 ml double cream
• 2 tsp vanilla extract
• 1 tbsp corn syrup or vodka (optional, for softness)
• a pinch of salt

Method

1. 1. Freeze the bowl 24 hours.
2. 2. Strain the yogurt through muslin in the fridge for 4 hours. Discard the whey, or keep it for baking.
3. 3. Whisk the strained yogurt with the sugar until completely dissolved — several minutes. Undissolved sugar is grainy and does not lower the freezing point.
4. 4. Whisk in the cream, vanilla, salt and the corn syrup if using.
5. 5. Chill the mixture 4 hours.
6. 6. Churn on stir speed for 20–25 minutes, until it is the texture of soft serve.
7. 7. Transfer to a container and freeze 2–4 hours to firm up.

It will not come out firm

Churned frozen yogurt is soft-serve consistency and that is correct. The freezer does the final setting.

Churning longer to firm it up does not work — past about 25 minutes the friction starts warming it and the texture gets worse.

Storing

Two weeks in the freezer, in a shallow container with cling film pressed onto the surface. Air is what causes freezer burn and large surface crystals.

Take it out 10 minutes before serving. Frozen yogurt sets harder than ice cream because of the lower fat.