Stabilisers at home: locust bean gum, guar, pectin, starch and gelatine

“Stabiliser” sounds like something from industrial production, but many of them are ordinary plant fibres or kitchen ingredients: flour from the seeds of the carob tree, guar gum, pectin from fruit, starch or gelatine. In homemade ice cream they are used in tiny amounts — often less than a gram per half-litre of mix — and they can significantly extend how long ice cream stays smooth.

What stabilisers do

According to Douglas Goff (University of Guelph), stabilisers bind water and thicken the part of the ice cream that doesn’t freeze. As a result, they:

• slow the growth of ice crystals and lactose crystals when the freezer temperature fluctuates,
• prevent the ice cream from shrinking,
• improve melting — the ice cream doesn’t turn straight into water,
• give the ice cream body.

They help most with ice creams low in fat and solids (gelato, sorbet, frozen yogurt) and with ice cream that has to last several days in the freezer. Goff’s rule: the higher the solids, the less stabiliser you need.

Doses and activation

Doses are in per cent by weight of the mix. Where it says “approximately”, we didn’t find a reliable source for ice cream.

Sources: Goff (Ice Cream Technology e-Book), the Ice Cream Science blog, which cites scientific studies, and Wikipedia (pectin, guar). We have not verified the doses of pectin, gelatine and starch for ice cream from a primary source.

For homemade ice cream, Goff gives 7 g of gelatine for roughly 3–4 litres of mix, which is about 0.2 %. David Lebovitz recommends about a teaspoon of gelatine per litre for sorbet.

How to add them

Stabilisers form lumps in water that are then hard to dissolve. So:

1. Mix them with the dry sugar from the recipe so that the grains are separated from each other.
2. Sprinkle them into cold or lukewarm liquid while stirring constantly, ideally with a stick blender.
3. Locust bean gum and carrageenan need heat — heat the mix to about 80 °C and hold it there for a while. At higher temperatures the viscosity of locust bean gum can drop.
4. Guar and xanthan work without cooking too — they suit mixes you don’t heat.
5. Let the mix age in the fridge. Locust bean gum reaches its highest viscosity after about 2 hours of hydration.

Combinations

In practice, stabilisers are often combined. Locust bean gum and guar reinforce each other, and a small amount of carrageenan prevents whey separation with locust bean gum. The Ice Cream Science blog cites a study in which a 9 : 1 mix of alginate and carrageenan at a dose of 0.2 % achieved the best rating after 16 weeks of storage.

In zmrzka’s recipes you’ll most often come across locust bean gum and guar (for example fior di latte or classic frozen yogurt), pectin in sorbets (lemon sorbet) and starch in the traditional Sicilian lemon crema.

Where to buy them and what’s on the label

Locust bean gum, guar, xanthan and pectin are sold in shops with baking and gluten-free cooking ingredients. On the labels of ready-made ice creams you’ll recognise them by their E numbers: E410 (locust bean gum), E412 (guar), E415 (xanthan), E407 (carrageenan), E440 (pectin).

Powdered ice cream bases already contain pre-mixed stabilisers — that’s not forbidden, but when you make ice cream from fresh ingredients you dose them yourself.

When you don’t need a stabiliser

• You’ll eat the ice cream on the day you make it.
• The mix is high in fat and has lots of yolks — yolks and fat provide body on their own.
• You’re making granita, where crystals are wanted.

If ice cream turns icy in the freezer after a few days, a stabiliser is one of the most effective remedies. Other causes of iciness are described in the article Ice crystals and texture.