→ Open the Ice Cream Lab (the calculators)
Why ice cream is arithmetic
Ice cream is frozen foam made of water, fat, sugar and solids. Whether it melts creamy or comes out of the freezer like a brick is decided almost entirely by composition — not by the machine. The Ice Cream Lab tracks four quantities live:
- Fat (ice cream 10–20%, gelato 4–9%, vegan 9–14%): carries flavour, makes it creamy.
- Sugar (14–24%): sweetens and keeps it soft — it is the antifreeze.
- MSNF (milk solids non-fat, 7–12%): binds water, prevents crystals.
- Total solids (36–44%): the more, the finer the texture.
Per ingredient: share% = Σ(grams × content%) ÷ total grams. That's it — bookkeeping, not witchcraft.
POD and PAC: sugar's two superpowers
Every sugar has two independent properties, both measured in sucrose equivalents (table sugar = 100):
- POD = sweetening power. Dextrose 74, invert/agave 125, lactose only 16, glucose syrup DE60 63.
- PAC = anti-freezing capacity. Dextrose 190, invert 190, glycerine 371, salt 585 (!).
The professional's trick: swap sugar types instead of changing the amount. Ice too hard? Replace 20 g of sugar with dextrose — nearly the same sweetness, double the antifreeze. Too sweet? Use glucose or maltodextrin — body without sweetness.
Freezing point & serving temperature (the Leighton table)
Water with dissolved sugar freezes below 0 °C — the more dissolved, the lower. We normalize PAC to the water phase (PAC ÷ water% × 100) and read the freezing-point depression (FPD) from the classic Leighton table of 1927. As the mix freezes, pure water freezes out first; what remains grows ever more concentrated and harder to freeze. Following Raoult, approximately: frozen water(T) = 1 − FPD ÷ T.
Ice cream scoops perfectly when ~72% of the water is frozen: T_serving ≈ −FPD ÷ 0.28. If your freezer sits at −18 °C but your ice cream wants −11 °C, temper it for 10 minutes — or raise the PAC.
Freezing-time forecast (Plank)
How long until a container's core is frozen through? The Lab estimates it with Plank's equation for cylinders: t = ρ·L/(T_f−T_a) · (P·D/h + R·D²/k) — density, latent heat (≈334 kJ/kg × water fraction), container diameter, the freezer air's heat transfer and the frozen mix's conductivity, plus a 35% safety margin. A Creami pint at −18 °C: about 16 hours — which is why Ninja says "freeze 24 h flat and level". Both are right: 16 h of physics plus an 8 h cushion.
Sorbet: the 27–32 Brix rule
Sorbet is fruit + sugar + water. Target: 27–32% total sugar (degrees Brix). Every fruit brings its own sugar (strawberry ≈7%, mango ≈14%, banana ≈18%) — the calculator subtracts it: addition = target% × total − fruit sugar. Fruit-share guidance: citrus 15–30%, melon 60–70%, everything else 25–50%. Making 25% of the addition glucose syrup rounds the sorbet and refines the crystals; 2% lemon juice wakes the fruit up.
Fruit in ice cream: macerate or get pebbles
Fruit pieces are 85–90% water with little sugar — inside ice cream they freeze rock hard. The fix: rest the fruit with ⅓ of its weight in sugar (half sucrose, half dextrose) for 30 minutes. Osmosis pulls the sugar in and lowers the pieces' freezing point. The fruit-mix calculator also shows how the addition dilutes your base.
Blending milk & cream: the Pearson square
Recipe calls for 25% cream, you have milk 3.5% and cream 35%? parts cream = target − milk fat = 21.5, parts milk = cream fat − target = 10. Out of 500 g that is 341 g cream and 159 g milk. Read diagonally — hence "square".
Vegan: same physics, different pantry
Without dairy fat, creaminess comes from coconut cream, cashews and nut butters; without milk protein there is no natural crystal protection — hence 0.15–0.35% stabilizer (guar/xanthan) is mandatory. Plant drinks are mostly water, so vegan needs more solids (36–44%) and a higher PAC (26–30). Also: honey is not vegan, and buy dark chocolate without milk fat.
The Ninja Creami in three sentences
1) Fill only to the MAX FILL line and freeze 24 h flat on a level shelf. 2) Spin on "Lite Ice Cream" (or Sorbet). 3) Crumbly? Not a mistake: add 1 tbsp of liquid, re-spin, done. Chunks go in last via the mix-in cycle.
→ Open the Ice Cream Lab (the calculators)
All calculators with live balance, Remy's tips and formula explanations — and every Ninja recipe on the site loads into the calculator with one click.
Originally published on traubenliebe.ch — sources referenced in the article: