Berries

Berries keep 3–7 days refrigerated, and the single most effective thing you can do is not wash them until the moment you eat them. Surface moisture is what mold needs, and a rinsed container of berries will mold in a day.

Store them in the refrigerator in a shallow, ventilated container — the clamshell they came in is usually fine — lined with a paper towel to absorb condensation. Do not pile them deep; the weight crushes the bottom layer and released juice feeds mold.

Sort them when you get home. One moldy berry will infect its neighbors within a day, so removing it immediately protects the rest.

A dilute vinegar rinse (one part white vinegar to three parts water) followed by thorough drying does extend their life, by killing surface mold spores. The drying matters as much as the vinegar.

Berries freeze extremely well for 8–12 months. Freeze them spread on a tray first, then bag them, so they stay loose.

Berries are the most perishable fruit in a supermarket, and the reason is structural: they have almost no protective skin.

Most fruits have a waxy cuticle that resists water loss and microbial entry. Berries have a very thin one — raspberries and blackberries have essentially none, since they are aggregates of tiny individual fruitlets with an enormous surface area and a hollow core. That is why raspberries last two or three days while blueberries, which have a genuine waxy bloom, last two weeks.

The organism responsible is usually Botrytis cinerea, gray mold, which is present on virtually all fruit at harvest and simply waits for the right conditions. It grows at refrigerator temperature, slowly, and it spreads by direct contact — which is why one moldy berry becomes a moldy container so quickly.

Because berries are high in acid and sugar rather than protein, they are not a significant bacterial-pathogen risk in the way that leafy greens or melons are. Mold is the practical issue.

USDA guidance is to discard moldy soft fruit entirely rather than cutting away the spot, because mold filaments penetrate high-moisture foods invisibly and some molds produce mycotoxins. Berries merely touching a moldy one should also go.