What a stabilizer does
An ice cream stabilizer is usually a food gum, a type of polysaccharide, that thickens the mix. According to the University of Guelph’s Ice Cream Technology e-Book, it also thickens the part of the ice cream that stays unfrozen in the freezer.
That thickening matters at every stage. The e-Book lists these jobs:
- In the mix: it helps keep the fat from creaming to the top. Carrageenan also stops the mix from separating into watery whey.
- As it leaves the machine: it helps hold air bubbles and keeps flavor swirls in place.
- In storage: it slows the growth of ice crystals and lactose (milk sugar) crystals, and it helps prevent shrinkage.
- When you eat it: it adds body and mouthfeel and helps flavor come through.
The storage job is the one most home cooks notice. Guelph explains that without a stabilizer, ice cream turns coarse and icy fairly quickly. Free water moves around and joins the crystals that are already there, so they grow. With a stabilizer, the largest ice crystals stay smaller.
Heat shock
Every time ice cream warms up, melts a little and refreezes, it gets icier. That is heat shock, and it happens when a pint rides home in a warm car or sits on the counter during dessert. The Guelph e-Book says stabilizers help limit this damage. It credits gel-like networks that hold free water and keep it from moving.
Too much of a good thing
Stabilizers have limits. Guelph warns that too much makes the mix too thick before freezing and gives a heavy, chewy or gummy body. It can also make the ice cream melt in an odd way, because the melted ice cream stays too thick.
Common stabilizers you will see on labels
The Guelph e-Book names these:
| Stabilizer | What Guelph says |
|---|---|
| Locust bean gum (carob bean gum) | A common choice, often blended with others |
| Guar gum | Dissolves more easily in cold mix than locust bean gum, so it suits HTST pasteurization |
| Carboxymethyl cellulose (CMC) | A common stabilizer |
| Carrageenan | Not used alone; added as a secondary ingredient to stop wheying off |
| Xanthan gum | Used to a lesser extent |
| Sodium alginate | Used to a lesser extent |
| Gelatin | Once used almost exclusively; now largely replaced by plant gums for effectiveness and cost |
Guelph also notes that factories often combine two or more stabilizers because they work better together. So a label that lists guar gum, locust bean gum and carrageenan is normal.
What an emulsifier does
An ice cream emulsifier works on fat, not water. Each emulsifier molecule has one end that likes water and one end that likes fat. The Guelph e-Book explains that it sits where fat droplets meet the watery part of the mix and lowers the tension there.
The surprising part is what happens next. Adding an emulsifier pushes milk protein off the surface of the fat droplets. That weakens the droplets just enough that some of them partly join together during churning, in a controlled way. Guelph says the result is a smooth, dry-looking ice cream that holds air well and melts cleanly.
Egg yolk was the first emulsifier
According to Guelph, the original ice cream emulsifier was egg yolk. Today, mono- and diglycerides and polysorbate 80 are the main ones in factory ice cream. Buttermilk and glycerol esters are other sources. The e-Book says all of these are generally recognized as safe (GRAS).
So if you make a custard base with yolks, you are already using an emulsifier.
How much factories use
The amounts are tiny. Guelph says stabilizers and emulsifiers together make up less than half a percent of ice cream by weight.
The e-Book’s general mix ranges are:
- Stabilizers: 0% to 0.4% of the mix
- Emulsifiers: 0% to 0.25% of the mix
Its suggested hard-frozen mixes go further. At 10% fat, it suggests 0.35% stabilizer and 0.15% emulsifier. At 16% fat, those fall to 0.15% stabilizer and 0.10% emulsifier. Guelph notes that richer mixes need less: more total solids means less need for stabilizer, and more fat means less need for emulsifier. It also says manufacturers usually follow the recommendations of the company that sells them the stabilizer.
To put that in kitchen terms, by our arithmetic, 0.15% to 0.35% of a 1,000-gram (about 1-quart) mix is 1.5 to 3.5 grams. Keep in mind these are factory numbers, worked out for factory equipment and storage.
Reading the label at home
A few things on a label may surprise you:
- Your cream may already contain them. The U.S. standards for heavy cream, light whipping cream and half-and-half list emulsifiers and stabilizers as optional ingredients. Check the carton.
- Milk proteins can count as stabilizers. The U.S. ice cream standard (21 CFR 135.110) allows hydrolyzed milk proteins as stabilizers, at no more than 3% by weight, in a mix with at least 20% total milk solids. It also allows caseinates in mixes with at least 20% total milk solids.
- Store-bought and homemade differ on purpose. The Cuisinart ICE-21 booklet says store-bought frozen desserts use gums and preservatives to make them firmer, and its home recipes do not.
Should you add a stabilizer for homemade ice cream
You do not have to. The Cuisinart, Ninja and KitchenAid manuals do not add a stabilizer to their recipes. Our own base formulas do not add a stabilizer or emulsifier either, apart from egg yolk in the custard formula.
The one maker-sourced stabilizer for home cooks comes from a 1980 home-freezer guide hosted in the Guelph e-Book. It uses gelatin: one 7-gram (1/4-ounce) packet per about 2 liters of mix. The guide says to stir the gelatin into the sugar before adding it to the liquid. It explains that gelatin absorbs some of the free water and helps prevent large crystals.
If you want to try guar gum in ice cream, the sources we use do not give a home dose. Our suggestion is to stay well inside Guelph’s factory range, weigh it on a gram scale, and use less in rich, high-fat bases. Watch for a gummy or chewy texture as a sign you went too far.
A homemade batch you eat within a few days may not need any of this. A stabilizer earns its place when ice cream sits in the freezer for a while or gets warmed and refrozen often.
To see how fat and solids add up in your base, use the Open the Base Builder button above. The calculators run in your browser, and the numbers you type are not sent to our server. The Read the glossary button explains terms like overrun and total solids.
FAQ
Are stabilizers in ice cream safe?
The Guelph e-Book says the common emulsifiers are generally recognized as safe (GRAS). Stabilizers are used in very small amounts, together with emulsifiers less than half a percent of the ice cream by weight.
What does guar gum do in ice cream?
It thickens the mix and the unfrozen water, which slows ice crystal growth. Guelph notes it dissolves more easily in cold mix than locust bean gum.
Is egg yolk a stabilizer or an emulsifier?
Guelph describes egg yolk as the original ice cream emulsifier. It helps shape the fat structure in a custard base.
Why does my homemade ice cream get icy after a few days?
Without a stabilizer, free water moves and joins existing ice crystals, so they grow. Warming and refreezing (heat shock) speeds this up.
Can I use gelatin instead of a gum?
A 1980 home guide in the Guelph e-Book uses one 7-gram packet per about 2 liters of mix, stirred into the sugar first. Factories have mostly moved to plant gums for effectiveness and cost.