Interactive lesson

Sugar-free fruit butter, step by step

Interactive lesson: from a crate of plums to a jar on the shelf — fruit, pans, kettle, pan and oven, the thickness test and the water bath.

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The whole lesson as text

1. Fruit for butter

Sugar-free fruit butter keeps only if the fruit is acid and sound.

Acid, ripe fruit — For butter use plums, apples, quinces, apricots and sour cherries. Pick the fruit fully ripe, even overripe, but sound.
Plums are the best — From 4–5 kg (9–11 lb) of late prune plums or damsons you get roughly 1 kg (2.2 lb) of thick butter. Apples need 5–6 kg, and quinces give plenty of pectin.
Pears and figs — Add 30 mL (2 tablespoons) of bottled lemon juice or 2 g (½ teaspoon) of citric acid per 1 kg of butter. Measure the pH: the target is 4.2 or lower.
Pumpkin stays out of jars — Pumpkin, carrot and beetroot are low-acid vegetables, and there is no tested method for such purées. Store pumpkins whole, freeze the purée or dry it.

Why: When you drive most of the water out of fruit, what is left is a concentrate of its own sugar and acid, and germs find it hard to multiply in that. But slowly is not the same as never, so the choice of fruit decides.

A plum that has started to wrinkle at the stalk has the most sugar and the least water.
The yield figures are approximate: they depend on the variety, the year and how thick you like your butter.

2. Preparing the fruit

From crate to kettle: sort, wash, stone and weigh.

Bin rotten and mouldy fruit — Sound fruit goes into the kettle, rotten and mouldy fruit into the bin. Not "because it all gets cooked anyway": the mould toxin stays.
Wash and drain — Wash the fruit under running water and leave it to drain.
Take out the stones — Halve the plums by hand or with a knife and take out the stones. It goes faster when some people wash and others stone.
Weigh and cook — Weigh the prepared fruit and note it in the diary. Cook ripe plums the same day or the next.

Why: Mould makes toxins, such as patulin in apples and pears, and cooking does not reliably destroy them. The longer fruit stands, the more of its sugar the yeasts use up, and the more time mould gets.

For 30 kg (66 lb) of plums allow roughly 2–3 working hours for two people.
Apples and quinces need no peeling if you sieve the butter; cook quinces first with 100–200 mL of water per kilogram.