Storing nuts so they stay fresh

A bag of nuts left on the counter for a month tells a sad story. The crunch softens, the sweetness fades, and the taste drifts toward something flat and faintly paint-like. The cause is not mysterious. Nuts are rich in natural oils, and oils react with air, light and warmth. The fix is not complicated either: keep them cool, dark and sealed, and buy only what you will use in a reasonable time.

The three enemies

Heat. Warmth speeds up the chemical changes that make oils turn stale. A cupboard next to the oven is the worst possible spot.

Light. Sunlight and bright kitchen lights also help break down fats. Clear jars on a sunny windowsill look lovely and keep nuts badly.

Air and moisture. Oxygen drives staleness, and damp air makes nuts soft or even mouldy. Leaving a bag open invites both.

If you remember nothing else, remember this trio. Everything below is a way of keeping nuts away from them.

Pantry storage

For nuts you will eat within a few weeks, the cupboard is fine if it is truly cool and dark.

1. Move nuts from their original bag into an airtight container, such as a glass jar with a rubber seal or a tin with a snug lid.
2. Choose a container that fits the quantity. A half-empty jar holds extra air.
3. Store it away from the cooker, kettle and sunny windows.
4. Label the lid with the purchase date. Memory is unreliable.

Whole, shelled raw nuts such as raw almonds are the most stable in a pantry. Roasted nuts, ground nuts and chopped nuts have more exposed surface, so they do not keep as long.

Fridge and freezer

Cold slows the reactions that spoil nuts, which makes the fridge and freezer excellent for anything you will not use quickly.

• Fridge: good for a few months, especially for nuts with a higher oil content such as walnut halves and pecan halves. Keep them in a sealed container so they do not pick up odours from other foods.
• Freezer: suitable for longer storage. Use freezer bags with the air squeezed out, or a rigid container, and label them with the date.

When you take nuts out of cold storage, let the sealed container come to room temperature before opening it. Opening it early lets condensation form on the nuts, which makes them soggy. Most nuts also freeze without clumping, so you can scoop out just what you need and reseal.

If you want a quick crispness boost after cold storage, warm them on a tray at 150C (300F) for 5 minutes and cool again.

Which nuts need extra care

Not all nuts keep equally well.

• Walnuts and pecans: high in oils, so they benefit most from the fridge or freezer.
• Almonds and hazelnuts: fairly sturdy when whole, but ground or flaked forms go stale sooner.
• Cashews: moderate keepers, best in a cool, sealed container.
• Pine nuts: very oily and quick to turn, so buy small amounts and store cold. Our pine nuts are best used soon after opening.
• Chopped and ground nuts: more surface area means faster staleness. Store them cold and use within a few weeks.

For baking staples, a small bag of pecan pieces kept in the freezer is always ready for a quick bake.

Roasted, salted and flavoured nuts

Roasting changes the structure of the surface and often makes flavour more delicate. Salted and glazed nuts also attract moisture, which can leave them tacky or soft.

• Cool roasted nuts completely before sealing them.
• Keep flavoured nuts in airtight containers and eat them first.
• If glazed or sugary nuts turn sticky, store them with a sheet of baking parchment between layers.

For the home-roasting side of things, see how to roast almonds at home.

How to tell if nuts have gone off

Trust your nose and your teeth.

1. Smell: fresh nuts smell sweet or neutral. Stale ones smell sharp, sour, soapy or like old crayons or paint.
2. Taste: a bitter, harsh or metallic taste means the oils have turned. Spit it out and discard the batch.
3. Texture: soft, rubbery or limp nuts have absorbed moisture. This is not harmful but they will taste dull.
4. Appearance: discard any nuts with mould, dark spots or a damp, musty smell.

If in doubt, throw them out. The science behind this is explained in why nuts go rancid, and the general term is rancidification.

Buying with storage in mind

A few habits make life easier:

• Buy smaller amounts of oily nuts, more often.
• Pick sealed, well-packed bags over loose scoops where you can.
• Avoid stocking up on nuts you use only in occasional recipes.
• Rotate your stock so the oldest is used first.

A last word

A jar, a cool cupboard and a bit of fridge space will keep most nuts tasting good for months. Add a date label and a quick sniff before you bake, and wasted nuts will become a thing of the past. Your next batch of banana bread will thank you.