Half an avocado in the fridge until tomorrow is almost always brown, sad, and headed for the bin - but it doesn't have to be. There are a few simple tricks that slow the browning and extend the fruit's life after cutting, and you already have most of them at home.

Leave the pit in. The part protected by the pit oxidises more slowly because less surface is exposed to air. Drip lemon or lime over the cut surface - the acid delays browning, the same principle that keeps apples and pears from turning dark. Cover the surface with cling film in direct contact with the pulp; the film has to touch the flesh itself to cut down on contact with air. And always keep it in a well-sealed container - the less oxygen, the longer the colour, taste, and texture last.

There are less obvious methods too. A thin layer of olive oil over the pulp creates a barrier that slows oxidation. If the avocado is very ripe, mash it into a purée with a few drops of lemon and seal it airtight. There's also the onion trick: pieces of onion in a sealed container (without touching the avocado) release sulphur gases that slow browning - but be careful, the avocado absorbs the smell, so this only works for savoury recipes.

The combination that works best brings it all together: pit plus lemon plus film stuck to the surface plus an airtight container in the fridge - and that way the avocado lasts two to four days. You can also freeze it, but only mashed into a purée (with a little lemon), since freezing destroys the creamy texture - ideal for guacamole or smoothies, not for salad. A little science for something so ordinary, but anyone who's binned half an avocado knows it's worth it.