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How much cider will I lose, and how much should I hold back?

What racking costs across a batch, and therefore how much to keep aside so vessels can be kept full. Headspace is the first-named cause on the volatile acidity record and appears in the prevention list of three more faults; this is the arithmetic that lets you see the problem in September rather than in March.

Topping-up reserve

Once off the gross lees, once a couple of months later, and usually once before packaging.

Four per cent suits a reasonably clear cider moved carefully. The first racking off heavy lees loses more.

Hold back

2.9 L

Cider remaining: 22.1 L

This is an estimate from a model, not a measurement.

How this is worked out
  1. Starting volume: 25.0 L
  2. Loss each racking: 4.0% — about 1.0 L on the first
  3. After all rackings: 25.0 × 0.960^3 = 22.1 L
  4. Total lost to lees and lines: 2.9 L
  5. What that means: hold back about 2.9 L, or plan to move into vessels totalling 22.1 L
What this assumes (4)
  • The loss figure is a working range rather than a constant. Four per cent per racking suits a reasonably clear cider transferred carefully; a heavily sedimented first racking off gross lees loses considerably more, and a final polish racking loses less.
  • The point of the figure is the vessel, not the volume. A batch that has shrunk below what its container holds needs a smaller container or topping up — leaving the headspace is how volatile acidity, oxidation and film yeast all begin.
  • Topping up with water dilutes everything the fruit provided in exactly the same proportion. Topping up with a sound cider of similar character does not, which is the reason to hold some back rather than to buy some later.
  • This assumes each racking takes the same proportion, which is a simplification: in practice the first is much the largest.

The least interesting arithmetic on this site

And the one that prevents the most. Air space above a maturing cider is the first-named cause on the volatile acidity record, and it appears in the prevention list of oxidation, acetification and film yeast as well. Acetic acid bacteria are obligate aerobes and cannot work in a genuinely full sealed vessel; film yeast needs a surface to grow on. Both problems are a consequence of a number nobody worked out in advance.

The point of the figure is not the volume. It is that a maker who has not done this discovers at the second racking that they have twenty-two litres and a twenty-five litre vessel, and by then the choice is between accepting a headspace and finding a smaller container they do not own. Working it out in September is free; working it out in March is not.

Topping up with water dilutes acid, tannin, sugar and aroma in exactly the same proportion. Topping up with a sound cider of similar character does not, which is the reason to hold some of your own back rather than to buy some later. The operation itself.

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Where this reading comes from

Guides that reach this calculator, and what the number decides once you have it.