Lipids

Lipids are the broad family of hydrophobic biomolecules — fats, oils, waxes, phospholipids, sterols, fat-soluble vitamins and related compounds — defined by insolubility in water and solubility in organic solvents. They supply concentrated energy (9 kcal/g), carry fat-soluble vitamins (A, D, E, K), build cell membranes (phospholipids, cholesterol), insulate and protect organs, and give foods texture, mouthfeel and flavour. In food science, lipid oxidation — the free-radical chain reaction producing rancid off-flavours — is the central spoilage chemistry of fatty foods, while dietary lipid profiles (saturated, trans, omega-3/6 balance) link to health, so both quality and nutrition turn on lipids.