Limes

Limes keep about a week on the counter and 3–4 weeks refrigerated — and they benefit from refrigeration more than lemons do, because they dry out faster.

Store them loose in the crisper, or in a sealed container of water for the longest life. Avoid a sealed dry bag, which traps humidity against the peel.

Choose limes that feel heavy for their size with thin, smooth, glossy skin. A light lime with thick pebbled skin will yield very little juice.

Roll a lime firmly under your palm before juicing, or microwave it for ten seconds, to increase yield noticeably.

Zest freezes indefinitely; juice freezes perfectly in ice cube trays.

Limes are thinner-skinned than lemons and have a correspondingly weaker moisture barrier, which is the main reason they dehydrate faster and benefit more from refrigeration.

They are also non-climacteric and are harvested green — that is their ripe state, not an early one. A lime turning yellow is not ripening; it is aging, and a yellow lime is typically past its best with a duller, less aromatic juice. This is the opposite of the intuition most people bring from other fruit.

Their acidity is extreme, at a pH around 2.0–2.4, which effectively rules out bacterial growth. Mold and dehydration are what actually limit them.

The characteristic failure is a lime going hard, light, and brown-patched, with the flesh inside dried into fibrous segments. The exterior can look reasonable while the interior has become useless, which is why weight is a more honest test than appearance.

Penicillium mold at the stem end means discard the whole fruit.

One practical note: the phototoxic compounds in lime peel can cause a skin reaction on sun exposure after handling — sometimes called margarita burn. Wash your hands after zesting if you are outdoors.