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Among common vegetables, raw spinach provides about 2.7 mg iron per 100 g, beet greens about 2.6 mg, asparagus near 2.1 mg, and Swiss chard around 1.8 mg. These are total-iron numbers; vegetable iron is nonheme and is generally absorbed less efficiently than heme iron.
Apples do not share one shelf life. Genetics affects how fast a cultivar respires, responds to ethylene, softens and develops storage disorders. Commercial cold and controlled-atmosphere storage slows those processes, which is why some varieties remain saleable for months longer than others.
Strawberries combine delicate skin, abundant water, rapid metabolism and susceptibility to gray mold. Refrigeration slows those processes but does not stop them, which is why one damaged berry can deteriorate quickly and affect its neighbors.
For most intact fruit, washing shortly before you eat or cut it is the simplest approach. Rinse under running water, do not use soap, and dry if needed. If you wash before storage, dry the fruit thoroughly because lingering moisture can encourage faster deterioration.
There is no universal winner. Cooking can reduce heat- and water-sensitive nutrients such as vitamin C and folate, while also breaking cell walls and increasing the availability of carotenoids such as lycopene in tomatoes and beta-carotene in carrots and spinach.
Broccoli yellowing usually signals senescence: chlorophyll breaks down as the florets age, especially with prolonged storage, warm temperatures, or ethylene exposure. UC Davis considers yellow florets the end of commercial shelf life, but yellow alone is not a safety diagnosis; mold, slime, rot, and off odors are different signals.
Climacteric fruits can continue ripening after harvest: bananas, avocados, pears, apples, mangoes, kiwifruit, peaches, and plums are common examples. Pineapple, citrus, grapes, strawberries, cherries, and watermelon are non-climacteric and do not develop much additional sweetness once picked.
Fresh mushrooms deteriorate quickly. Slight drying, wrinkling, or darkening can simply mean age, while a slippery slime, sour or strong off odor, visible mold, and watery breakdown are clear reasons to discard them.
Bananas respond strongly to ethylene, a gaseous plant hormone that triggers ripening. Apples, pears, avocados, and other climacteric fruits also release ethylene, so grouping ripe fruit together can increase local exposure and speed softening, yellowing, aroma development, and starch-to-sugar conversion.
Bananas darken as they ripen because tissues change and phenolic compounds oxidize. Bruising and cold exposure can accelerate the browning. A nearly black peel can still hide usable flesh; mold, leaking liquid, a rotten odor, or badly decayed flesh are different warning signs.
Freezing does not strip vitamins out of fruit. Some vitamin C and other sensitive compounds can decline during preparation and long storage, but properly frozen fruit retains nutritional value very well. Fruit frozen soon after harvest can even compare favorably with fresh fruit that has spent many days in transport and refrigeration.
Pink or reddish ribs do not automatically mean lettuce is bad. UC Davis describes pink rib as a postharvest physiological disorder associated with overmaturity, long storage, or warmer-than-recommended conditions. If leaves remain reasonably crisp with no mold, slime, or off odor, the discoloration is usually a quality issue.