🧊 Refrigerator

The refrigerator is the main place at home for storing milk and other perishable foods. Cold slows the growth of bacteria: at room temperature, the number of microbes that cause food poisoning can double every 20 minutes. The US FDA advises keeping the refrigerator at no more than 4 °C, the UK FSA at 0 to 5 °C, and the freezer at about −18 °C.

The built-in control rarely shows the real temperature, so the FDA advises placing a separate thermometer inside and checking it often. Don't pack the fridge to the brim: cold air needs to flow freely around the food. Wipe up spills straight away, since Listeria bacteria grow even in the cold, and keep food covered.

Timing matters too. Put perishable food in the cold within 2 hours of buying it, or within an hour when it is above 32 °C. The FSA advises cooling hot food first and putting it in the refrigerator within 1–2 hours, then eating leftovers within two days or freezing them. Don't leave the door open for long, as that makes the refrigerator work harder. Electric home refrigerators spread in the 20th century and have since become a standard part of the kitchen.

Why it matters to you. The date on a milk carton only applies if the product is stored under the stated conditions, so the FSA advises following the instructions on the label. Use a thermometer to check that your refrigerator stays at 4–5 °C. If the power goes out, keep the door closed: according to the FDA, food is safe if the refrigerator is still at 4 °C or below, or if it has been out of the cold for no more than 2 hours.