❄️ Cold chain

The cold chain means unbroken cold along the whole journey of a food, from the farm to the fridge at home. Every link must keep the temperature low: the cooling tank on the farm, the milk tanker, the plant's cold store, the refrigerated truck, the shop's display case and the home fridge. If even one link fails, it is called a break in the chain.

Why does it matter? In the warm, bacteria in milk multiply much faster, and even a few extra degrees speed up spoiling. Pasteurisation kills disease-causing germs, but not all bacteria and spores, so pasteurised milk needs cold too. A break in the chain shortens shelf life and raises the risk of stomach infections. As the Tetra Pak handbook puts it, the technology is only as strong as the weakest link in the chain.

Carrying food under cold began in the mid-19th century, on refrigerated ships and in rail wagons packed with ice. Later came trucks with refrigeration units. In the EU, cold for raw milk is set by law: on the farm no higher than 6–8 °C, during delivery to the plant no higher than 10 °C, and at the plant no higher than 6 °C.