The short answer
Achaar lasts for months because oil, salt and spice preserve it, but it can spoil if moisture gets in. Throw it away if you see white or green fuzzy mould, smell anything rotten or yeasty, or notice fizzing or bubbling. Check the best-before date on the jar as well.
Signs it has turned
- Fuzzy white, green or black mould on the surface or pieces.
- A sour, yeasty or rotten smell instead of a spicy one.
- Bubbles or fizzing when opened.
- Slimy pieces.
Why it happens
Almost always moisture: a wet spoon, water dripping in, or pieces left above the oil line. Heat and sunlight speed it up.
Is a little spoilage safe to scrape off?
No. Mould can spread through the oil. If you see it, discard the whole jar.