The thermophysical property that quantifies how fast heat conducts through a material, expressed in watts per metre per kelvin (W/m·K) — equivalently joules per second per metre per kelvin. Conductivity governs heat penetration during cooking, freezing, and sterilization: metals move heat rapidly, while air pockets, fats, and porous structures insulate. In canning it fixes the location of the cold spot — the slowest-heating point the process must sterilize — and in freezing it sets how quickly the thermal centre reaches target temperature. Engineers measure or model conductivity to design processes that achieve safety without overcooking the surface to heat the centre.