An unopened packet of namkeen will hold its crunch for months. An open one can go limp in a single humid afternoon in Kolkata. The difference is not age — it is moisture.

Fried and roasted snacks are dry by design, and dry things pull water out of the air. Once that starts, no amount of sealing reverses it. So the job is to slow it down.

Six things that actually help

• Squeeze the air out before you seal. Air in the packet is air carrying moisture. Push it out, then fold the top over twice and clip it. This single habit does more than any container.
• Use a container with a gasket. A steel dabba with a loose lid looks airtight and is not. If the lid does not have a rubber seal, you are storing your chanachur in a slightly smaller room.
• Keep it away from the stove. The cupboard above the hob is the worst place in an Indian kitchen — warm, and repeatedly steamed every time something boils.
• Do not refrigerate it. This is the mistake we hear most. A fridge is humid, and every time you take the container out, condensation forms on the cold snack as it meets warm air. It will be soft by the second day.
• Never put a damp spoon in. Or damp fingers. One wet contact point spreads through the whole batch faster than you would expect.
• Decant large packets. If you have bought a big pack, split it. Every time you open the main container you expose all of it. Keep a small working jar and leave the rest sealed.

Bringing back a soft packet

If it has already gone slightly limp and it does not smell off, you can usually recover it. Spread it on a tray in a single layer, put it in the oven at the lowest setting for eight to ten minutes, then let it cool completely before sealing.

That last part matters. Sealing warm snacks traps steam, and you will have undone the whole exercise by morning.

This works once, maybe twice. It does not work on something that has turned — if the oil smells sharp or the taste is bitter at the edges, the fat has oxidised and no oven will fix it.

How long is reasonable

Opened and stored properly, a fried mix is at its best for about three to four days and perfectly good for a week. Roasted items like our chana last longer, because there is less oil to go stale.

Every one of our pouches carries its pack date on the back, not just a best-before. It tells you what you actually want to know — how recently it was sealed.