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Fruit families ▾
Citrus Peel and pips do the work · 4/6Stone fruit Skin carries the pectin · 4/6Berries Fast, hot, short boils · 5/6Tropical Acid and pectin both added · 3/6Melons Low acid, corrected by hand · 4/6
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About this notebook

Tropic Jar is a working record of fruit preserves kept in numbers rather than in adjectives. Every entry names the fruit, the pectin it actually contains, the sugar ratio, the pH the batch has to sit at, and the temperature the gel forms at. There is no “cook until ready” anywhere in the collection, because “ready” is the thing being measured.

Why measurements instead of instincts

Jam fails in ways that look identical and have completely different causes. A soft set can mean too little sugar, too much water left in the pan, a pH above 3.5, or pectin that was boiled past the point where it can still set. A jar that weeps syrup can be under-acidified or simply over-cooked. You cannot tell those apart by looking at the jar, and reheating everything for another ten minutes makes about half of them worse. Naming the number that went wrong is the whole method here.

How a record is put together

Every preserve on the wall carries the same six pieces of information, so that two records can be compared without reading either of them in full:

  • Fruit and family — the five families on this site differ mainly in where their pectin sits: in the peel and pips, in the skin, in the seeds, or nowhere at all.
  • Pectin source — natural, added, or both, with the quantity that the recipe actually relies on.
  • Sugar ratio and target Brix — by weight, not by volume, and the Brix the finished jar should read.
  • pH and how it is reached — the acid added, the juice used, or the correction applied to a low-acid fruit.
  • Gel point — the temperature at which that specific combination sets.
  • Sealing and shelf life — boiling water bath, invert-hold, or a moulded block that is not sealed at all.

Then three stages — the fruit prepared, the boil, the jars filled — and a failure diagnosis listing the four things most likely to go wrong with that particular preserve.

What is deliberately not here

This is a home-preserving notebook, not a canning authority. It does not cover pressure canning, it does not give altitude corrections for boiling water baths, and it does not attempt low-sugar or sugar-free formulations, which need a different pectin system altogether. Where a preserve is genuinely risky to keep at room temperature, the record says so in plain words rather than burying it in a footnote.

Measuring equipment the records assume

A digital thermometer that reads to 0.1 °C, a refractometer or a jam thermometer, and pH strips accurate to 0.2. None of it is expensive, and all three are more useful than a decade of experience at telling you why a batch behaved the way it did.

Reaching us

Corrections are welcome and are the fastest way to improve this collection. Write to [email protected] — see the contact page for what we can and cannot answer.