Sugar is what makes sorbet scoopable
Sorbet is just fruit, water and sugar, but the sugar does far more than sweeten. It lowers the freezing point of the mix so that only part of the water turns to ice, leaving a soft, smooth texture. Too little sugar and the sorbet freezes into a hard block of ice crystals; too much and it never sets. Professional ice cream makers balance the mix by its sugar concentration, measured in degrees Brix.
Brix and the target
One degree Brix (°Bx) is one gram of sugar per 100 grams of liquid. A sorbet mix typically aims for 25 to 30 °Brix, with 28 a good starting point. Fruit already contains sugar: roughly 8 °Bx for lemon juice, 10 for strawberries, 12 to 15 for peaches or raspberries and 18 to 20 for mango or banana. A refractometer gives the exact figure for your fruit.
The formula
With F grams of fruit at b °Bx, W grams of water and a target T °Bx, the sugar to add is:
Sugar = (T × (F + W) − b × F) ÷ (100 − T)
Example
500 g of fruit purée at 12 °Bx, 200 g of water and a target of 28 °Bx:
- Sugar = (28 × 700 − 12 × 500) ÷ 72 = 189 g
- Total mix: 889 g, of which 56% is fruit
- That is about 378 g of sugar per kilogram of purée.
Tips for a smoother sorbet
- Dissolve the sugar in the water first, as a syrup, then mix with the cold purée.
- Replace 20 to 30% of the sugar with dextrose or glucose syrup for a softer texture with less sweetness.
- Lemon juice brightens flavor but adds little sugar; count it as fruit at about 8 °Bx.
- Chill the mix thoroughly before churning, and let hard-frozen sorbet soften for a few minutes before serving.