Avocado

Avocado storage depends entirely on ripeness, and getting it right is the difference between a good avocado and a wasted one.

Unripe (firm): leave on the counter, 3–5 days. To speed it up, put it in a paper bag with a banana or apple — their ethylene accelerates ripening. Refrigerating an unripe avocado stalls it permanently; it will never ripen properly afterwards.

Ripe (yields to gentle pressure): move to the refrigerator, where it holds for 3–5 days instead of going over in one.

Cut: brush the exposed flesh with lemon or lime juice, press plastic wrap directly onto the surface to exclude air, and refrigerate for 1–2 days. Leave the pit in the half you are storing — not because the pit does anything chemically, but because it physically covers flesh that would otherwise be exposed.

Avocado freezes only as puree, with lemon juice, for about 4–6 months. Whole or sliced, it thaws watery and stringy.

Avocados are climacteric fruit, meaning they ripen after harvest in response to ethylene rather than on the tree. Commercially they are picked hard and ripened deliberately, which is why the supermarket display is full of rocks and why the paper bag trick works — it concentrates the fruit's own ethylene.

Refrigeration below about 40°F causes chilling injury in an unripe avocado, damaging the cell membranes and the enzymes that drive ripening. The fruit then never softens properly and instead develops gray-brown patches and an off flavor. Once ripe, though, the fruit has finished the process and refrigeration simply slows further decline.

The browning of cut avocado is enzymatic browning, the same reaction as in a cut apple: an enzyme called polyphenol oxidase meets oxygen and produces brown pigments. It is entirely cosmetic — brown avocado is safe, just unappealing. Acid slows the enzyme, which is why lemon juice works, and excluding air works better still. The pit is not magic; it only shields the flesh beneath it.

Distinguishing over-ripe from spoiled: brown stringy fibers and darkened flesh are over-ripeness and can be scooped around. A sour or fermented smell, mold on the flesh, or flesh that has gone watery and separated means discard.