Quince

Quince behaves unlike most fruit. Raw, the flesh is so hard it can damage knives, and the astringency comes from tannins concentrated in the cell walls and the membrane between seed cavities. Cooking breaks down these tannins through heat and sugar, and the stone-like cells (called sclereids) soften. The flesh also contains lycopene, which is normally colorless but becomes visible red when the fruit's cell walls break down and acid is present—hence the characteristic pink blush when cooked with lemon juice or the skin on. This color is one of the defining visual markers of properly cooked quince. The fragrance, concentrated in the fruit's volatile oils, intensifies dramatically with heat, filling kitchens with a scent unlike any other autumn fruit.

Quince looks deceptively ordinary—often bumpy, faintly fuzzy like a peach, and ranging from golden yellow to pale green. The most reliable ripeness indicator is fragrance: a ripe quince will smell intensely floral and tropical from across the room. Avoid any fruit with soft spots, bruises, or blemishes, as these spread quickly and the fruit will not keep. Unlike apples and pears, quince does not continue to ripen significantly after picking—it can, however, develop more concentrated flavor in storage. Keep whole, unblemished quinces in a cool, dark place (a cellar or cold pantry is ideal) for up to 2–4 weeks. Once cut, use immediately or store submerged in acidulated water, but only for a day or two maximum.