Watermelon

A whole uncut watermelon keeps 1–2 weeks at cool room temperature and about 2 weeks refrigerated. Cut watermelon must be refrigerated and keeps 3–4 days.

Wash the rind before cutting. This matters more than it sounds — a knife drawn through an unwashed rind carries whatever is on the surface directly into the flesh you are going to eat.

Store cut watermelon in a covered container or tightly wrapped, not simply cling-filmed on the counter.

Whole melons are actually better slightly cool than fully refrigerated: research from the USDA has found that watermelons held at room temperature retain more lycopene and beta-carotene than refrigerated ones. Once cut, though, refrigeration is not optional.

Watermelon does not freeze well as chunks — it thaws watery and collapsed — but freezes fine pureed for drinks and sorbet.

Melons are treated with unusual seriousness in food safety guidance, and the reason is the rind.

Watermelons grow on the ground, in contact with soil and irrigation water, and their rind can carry Salmonella and Listeria. The flesh inside is sterile in an intact melon — but a knife cutting through a contaminated rind carries those organisms straight into the flesh. The flesh is then a near-perfect growth medium: high moisture, high sugar, and a pH around 5.2–5.6, which is high enough for bacteria to grow readily. Unlike citrus, melon is not an acidic fruit.

That combination — contaminated exterior, hospitable interior, eaten raw — is why cut melon is classified as a potentially hazardous food requiring refrigeration, and why melon has caused serious multi-state outbreaks in the US.

So the two rules that matter are: wash the rind before cutting, and refrigerate cut melon promptly, within two hours.

For quality, a whole melon that is spoiling develops soft sunken spots, and cut flesh turns slimy, sour-smelling, and mealy as it breaks down. Water pooling in the container is normal.

White streaks and hollow hearts inside are growing conditions, not spoilage.