What happens inside food when heat, water, mixing, fermentation and other cooking processes change its structure.
Firm, glassy, water-soaked-looking flesh around an apple core can be watercore, a maturity-related physiological disorder. It is not rot by itself, although severe watercore shortens storage life and can progress to internal browning and breakdown.
A mealy apple can still be sound. As apples age and their cell structure changes, the cells separate more easily instead of bursting and releasing juice, creating a dry, grainy bite. If there is no mold, rot, or off odor, the problem is mainly quality.
An artichoke that turns brown or nearly black shortly after cutting is usually undergoing enzymatic browning where the flesh meets air. If it was firm and sound before cutting, the quick surface color change does not mean it suddenly spoiled.
White or pale circles inside a beet are usually a physiological growth pattern called zoning, not rot. If the root is firm, smells normal, and has no wet breakdown, mold, or mushy tissue, the rings themselves do not make it unsafe to eat.
A dry, spongy or hollow center in a radish usually reflects overmaturity and lost eating quality rather than rot. If the tissue is clean and dry it may still be eaten; watery softness, slime, mold, or an off odor are reasons to discard it.
Garlic that turns blue or green during cooking is usually undergoing a harmless color reaction between compounds naturally present in the cloves. If the garlic was firm, clean, and normal-smelling before cooking, the new color alone is not a reason to throw the dish away.
A single dry brown ring can be peeled away if the rest of the onion is firm. Black powdery mold, wet or slimy layers, bad odor, or widespread internal damage means the bulb should be discarded.
Sprouted seeds inside squash are a maturity phenomenon called vivipary, not automatic spoilage. If the flesh is firm and normal-smelling with no mold, wet rot, or extreme bitterness, it can still be eaten.
Dark, dry edges on cut cabbage are often surface browning and dehydration. Trim the thin layer and inspect underneath; discard cabbage that is wet, slimy, soft, moldy, or rotten-smelling.
Tiny flat black specks in otherwise crisp cabbage may be pepper spot, a quality defect. Dark areas that are wet, translucent, mushy, slimy, or bad-smelling suggest damage or decay instead.
A cabbage-like or sulfurous smell can be normal for cauliflower, especially during cooking. Toss it when the odor is clearly sour or rotten and the florets are also slimy, wet, soft, or moldy.
A bitter eggplant is often simply overmature. Large seeds, spongy flesh, and dull skin support that explanation; discard it if bitterness comes with wet rot, slime, mold, or an off odor.