Ingredient

Avocado

The avocado problem is timing. It goes from hard to perfect to brown and stringy in about two days, and the window is short enough that most people buy them at the wrong end of it.

How to tell if it is ripe

Not by squeezing the middle, which is how supermarket avocados end up bruised for the next person. Two better tests.

Press gently at the stem end, near the top. A ripe avocado yields slightly there while the body still feels firm.

Flick off the small stem cap. Green underneath means ripe and good. Brown means overripe and probably stringy inside. If it will not come off at all, the fruit is not ready.

Colour helps for Hass — the commonest variety — which goes from bright green to near-black as it ripens. It is useless for the smooth, green-skinned varieties, which stay green whatever they are doing inside.

Controlling the timing

Avocados do not ripen on the tree; they ripen after picking, which is why you have some control.

• To speed it up, put it in a paper bag at room temperature. The ethylene the fruit gives off is trapped and accelerates the process. A banana or an apple in the bag speeds it further.
• To slow it down, put a ripe avocado in the fridge. That buys two or three days.
• Never refrigerate an unripe one. Cold stops the ripening process and it may never restart properly, leaving you with a fruit that goes from hard to bad without passing through good.
• Buy a mixture — one ripe, one nearly, one hard — if you want avocados across a week.

Why it goes brown, and what actually helps

Cut flesh browns because an enzyme in the fruit reacts with oxygen. It needs both, so anything that removes one of them slows it down.

Acid works, because the enzyme is much less active in acidic conditions. Lime or lemon juice on the cut surface is the most effective everyday measure, and it is why guacamole recipes all contain lime.

Excluding air works. Cling film pressed directly onto the surface, or a layer of water or oil, is genuinely effective — the key is direct contact with the flesh, not just a covered bowl.

Cold slows it, since the enzyme works more slowly at fridge temperature.

Leaving the stone in does almost nothing except protect the small area underneath it. It is not a trick, it is a coincidence.

Browning is a cosmetic and flavour change, not spoilage. Scraping off the brown layer leaves perfectly good fruit underneath — see brown avocado.

Using it

• Do not over-mash guacamole. Chunky is the point, and mashing releases more enzyme and more surface to the air.
• Salt and acid are what it needs, in more quantity than seems right. Avocado is fatty and bland and takes a lot of both.
• It does not really cook. Heat makes it bitter and the texture unpleasant. Grilled avocado is warm avocado at best; add it to hot dishes at the end.
• Blended, it makes things creamy — smoothies, cold soups, dressings — without dairy.
• An underripe one can be saved by slicing thinly and dressing it hard; it will never mash.

Common questions