Solving Ice Crystallisation in Artisan Gelato

Ice crystallisation is not usually a recipe fault. Gelato that is smooth out of the batch freezer and gritty on day three has a temperature history problem, and the recipe is the last place to look, not the first.

Crystals grow when water moves. Every time a product warms and re-freezes, small crystals melt and their water migrates to larger ones. The large crystals get larger. Perceptible grittiness starts around 50 microns, and a product only has to cross its freezing point a handful of times to get there.

Diagnose in this order

1. The cabinet

Put a probe in the product, not in the air. Air temperature in a display cabinet tells you almost nothing — it swings every time the door opens and every time the compressor cycles.

What you are looking for is swing, not the average. A cabinet holding a steady −13 °C is fine. A cabinet averaging −13 °C by alternating between −16 °C and −9 °C is destroying your product, and the average on the controller display looks identical.

Common causes: overloading past the load line, a blocked evaporator, a door seal that has hardened, or a cabinet sited where afternoon sun hits the glass. In an Australian shop, the sun one is far more common than anyone expects, and it is seasonal — a cabinet that behaved all winter can start failing in November.

2. The blast freezer

Gelato should go from the batch freezer to a blast cycle, not straight into display. The faster the core passes through the −1 °C to −5 °C zone, the smaller the crystals that form there.

If pans are going into the display cabinet to "firm up", that is the problem, and no recipe change will fix it.

3. Handling

Every trip out of the cabinet is a warming event. Pans left on a bench during a changeover, product decanted between containers, a tub topped up from a warmer tub — each of these costs texture.

Topping up is the worst of them, and the most common. Adding fresh product to a half-empty pan means the old product warms while the new is added, and now the whole pan carries the older product's crystal history.

4. The mix

Only now is it worth looking at the recipe. Three levers, in order of usefulness:

Freezing-point depression. Too little and the product sits too hard, gets scooped roughly and warms at the surface with every service. Swapping part of the sucrose for dextrose lowers the freezing point without adding sweetness — see the fundamentals of balancing a mix for why those two properties move independently.

Total solids. Under about 34% there is too much free water and nothing to bind it. This is the usual fault in home-style recipes scaled up commercially.

The stabiliser system. Stabilisers do not stop crystals forming. They slow water migration, which is a different and more useful thing: they make the product tolerant of the temperature abuse it is going to receive anyway.

A complete base takes all three off the table, which is a real advantage in a shop with variable staff. Sole Soft 400 at 350–400 g per litre and Base Cheesecake 500 at the same dosage are formulated as finished systems, so if a batch made from one goes gritty, you have effectively ruled out the mix and can concentrate on the freezer.

The Australian pattern

Grittiness that appears in November and clears in April is not a recipe drift. It is the cabinet losing the fight with ambient conditions.

Three things change at once in an Australian summer: ambient temperature, humidity loading the evaporator, and door-opening frequency roughly doubling. A cabinet sized for its winter duty can be marginal in February.

The practical responses are all operational: reduce batch size so product spends less time in display, service busy flavours from a smaller pan and hold the backup in the blast freezer, and get the condenser coils cleaned before the season rather than during it.

The overrun question

Overrun — the air whipped into the mix during churning — is a texture variable that gets discussed as a cost variable, which is why it is so often set wrong.

Air insulates. A gelato at very low overrun is dense and intensely flavoured, and it is also more vulnerable: with less air distributed through it, the product conducts heat more readily and its surface warms faster under a service lamp. Traditional gelato sits well below the overrun of industrial ice cream, and that density is the point — but it means the cabinet has to be better, not worse, than it would need to be for a lighter product.

Two practical consequences.

Do not chase lower overrun to sound more artisan unless your cabinet is holding a genuinely steady temperature. Density and a swinging cabinet is the worst combination available, and it shows up as grittiness within days.

Check that overrun is actually consistent between batches. A batch freezer run underfilled produces different overrun from the same machine run at capacity, which is one reason an oversized machine run half-full makes worse product than a right-sized one. If two batches of the same recipe behave differently in the cabinet, fill level is the first thing to check — before the recipe.

Where inclusions fit

A ripple or crunch does not cause crystallisation, but it changes how visible it is. A product with texture running through it masks moderate grittiness — the palate reads the intended texture rather than the fault.

Fanta Crumble is layered at 100–200 g per kilo as the tub is filled rather than stirred in, and it stays soft at cabinet temperature. Used properly it adds a baked-biscuit contrast. Used to hide a product that has been through four freeze-thaw cycles, it buys about a day.

Fix the cause. The inclusion is a flavour decision, not a repair.

A checklist for the next gritty batch

• Probe the product in the cabinet across a full trading day, not once.
• Confirm every pan goes through a blast cycle before display.
• Count how many times that pan has left the cabinet.
• Check the pan is not being topped up from a fresher batch.
• Only then look at sugars, solids and stabiliser.

Nine times in ten it is one of the first four.

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If you are reviewing your base system as part of fixing this, the 2026 Elenka catalogue sets out every base with its processing method and dosage, including the neutrals and stabiliser systems.