Fruit wash calculator

How to use it

1. Choose the fruit. Stones, cores and peel are allowed for: remove stones from stone fruit before mashing.
2. Weigh it. As bought or picked, whole.
3. Measure the sugar. Squeeze a few drops of juice onto a refractometer. Without one, keep the typical figure the calculator sets for ripe fruit of that kind.
4. Add water or sugar if you plan to. Thick fruits - bananas, mangoes, berries - need water to make a stirrable mash. Sugar raises the alcohol, though a pure fruit brandy uses none.
5. Check it. Once the mash is mixed, measure the gravity of the liquid with a hydrometer or refractometer.

How it works

The calculator takes off the parts that don't go in (stones, cores and peel) and the insoluble pulp, to find the weight of juice the fruit holds, and uses its °Brix to find the dissolved sugar. About nine-tenths of a ripe fruit's dissolved solids are fermentable sugars - the rest are acids, minerals and the like.

The liquid volume is the juice plus any water, plus the room taken by any sugar you add; from those come the gravity of the liquid and the strength once it ferments dry, assuming about 86% of the theoretical alcohol, as for a sugar wash.

Fruit is variable - the same variety can differ by several °Brix from one season to the next - so treat the result as a plan and measure the real thing.

Worked examples

20 kg of apples at 12 °Brix, with nothing added, give about 16.9 L of liquid at a gravity of 1.048, fermenting to about 6.3% ABV - much like cider.

20 kg of plums at 15 °Brix with 5 L of water and 2 kg of sugar start at 1.078 and should reach about 10.9%.

10 kg of ripe bananas (21 °Brix, peeled) with 10 L of water start at 1.032, for about 4.1%.

Questions

How much alcohol will my fruit make?

Most ripe fruit gives a mash of about 4–9% ABV on its own - apples and pears around 6%, grapes nearer 11%. Adding sugar raises it.

Should I add sugar to a fruit mash?

For a true fruit brandy, no: the fruit's own sugar gives the purest flavour. Adding sugar gives more alcohol from the same fruit, with a lighter fruit character.

Do fruit mashes make more methanol?

Yes. Methanol comes from the pectin in skins and flesh, so fruit mashes make more than sugar or grain washes. The methanol guide explains what that means and how to handle it.

Why remove the stones?

Stones of cherries, plums, apricots and peaches contain compounds that can form hydrogen cyanide and, in the spirit, ethyl carbamate. Remove them, or at least don't crush them.

Should I use pectinase?

Pectic enzyme breaks down the pectin, which frees more juice and sugar and makes a thinner mash that's easier to handle. It doesn't add alcohol on its own.