Why have my pickles gone soft, and is cloudy brine a problem?

Crispness in a pickle is a matter of the vegetable's cell walls holding together, and there are a handful of specific things that break them down. Cloudiness is a separate question that worries people more than it needs to, but occasionally matters a great deal, so it is worth being able to tell the two apart.

Safety

Step by step

1. Salt watery vegetables before pickling.Cucumbers, courgettes, marrow and onions are drawn down with dry salt or a strong brine for several hours, then drained and rinsed. This pulls water out so it cannot dilute the vinegar, and it firms the flesh. Skipping it is the single most common cause of a limp pickle.
2. Cut the blossom end off cucumbers.The flower end of a cucumber carries an enzyme that softens pickles. Trim about 3mm off that end — it is the end opposite the stalk — and the difference over a few weeks is noticeable.
3. Use vinegar of the right strength and do not dilute it.At least 5% acetic acid for anything not kept in the fridge. Weak or diluted brine both softens the vegetables and undermines the preservation.
4. Keep the jars cool and dark.Warmth softens pickles steadily. A cupboard next to the oven or a sunny shelf will turn a good jar limp in a couple of months.
5. Do not overheat the vegetables.Most vegetables go into the jar raw or barely blanched and have hot brine poured over. Actually cooking them in the brine gives a soft pickle from the start.
6. Read the cloudiness properly.Harmless: cloudiness from ground spices, from sediment out of unfiltered vinegar, from hard water minerals, or from iodised or anti-caking table salt. Also harmless: a cloudy brine in a fermented pickle, which is expected. Not harmless: cloudiness that appears suddenly in a previously clear jar, with bubbling, a lifted lid, sliminess or a yeasty or rotten smell.
7. Throw away rather than test by tasting.If the jar has a bulging lid, is fizzing, smells wrong, or has slimy or ropy brine, bin it unopened or with minimal handling. Tasting is not a safety test for anything, and a jar of onions is not worth it.

Tips

• Use pickling salt, or any pure salt without anti-caking agents or iodine. Those additives are the commonest cause of a harmlessly murky brine that looks alarming.
• A grape leaf, oak leaf, blackcurrant leaf or a pinch of loose black tea in the jar adds tannins, which help hold pickles crisp. It is a genuine old technique rather than folklore.
• Small, firm, freshly picked vegetables make crisp pickles. Anything that has sat in a fridge drawer for a week starts at a disadvantage no method will recover.
• Filtered or boiled-and-cooled water in the brine avoids most hard-water cloudiness.

Common mistakes

• Topping up a used jar with fresh vegetables and the old brine — The brine has already been diluted by the first batch and partly consumed. It no longer has the acidity to hold new vegetables safe, and the result is soft and potentially unsafe.
• Assuming cloudiness always means spoilage — Most cloudiness is spice sediment, salt additives or minerals, and the pickle is fine. Judge on the combination of signs — a lifted lid, gas, smell or slime — rather than on appearance alone.

If it doesn't work

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