Food processing machinery is the equipment that heats, cools and grinds food and seals it into packs. It ranges from a dairy's processing line to a pasta machine or a chocolate machine. It is one branch of special-purpose machinery.
Food machines have one strict need: hygiene. Every surface that touches food must be made of a food-grade material that does not rust or corrode, usually stainless steel. It must be easy to clean and have no corners where food can stay. The machine is cleaned in place, which means that cleaning liquid is pumped through its pipes without taking it apart.
After each production run, the line is cleaned in place. First, water rinses out the food that is left. Then a hot cleaning liquid, such as a caustic soda solution, is circulated through the pipes, followed by a rinse and sometimes a disinfectant. The whole cycle takes about an hour. The plant counts this hour as time when the machine is not producing, so food machines are designed to be cleaned fast. In India, food plants must also follow the hygiene rules of FSSAI, the Food Safety and Standards Authority of India, and the machine must make it easy to do so.
Take, for example, a dairy that packs milk in half-litre pouches. The line takes 1,000 litres of raw milk. It heats the milk to 72 °C for 15 seconds, to kill harmful germs, and then cools it at once to 4 °C. A packing machine forms a pouch from plastic film, fills it with 500 ml and seals it. 1,000 litres make 2,000 pouches. Each pouch is printed with a date and a batch code.
The stages use pumps and valves, heating and coding printers. The records of the batch are the basis of food traceability: if a batch of milk is found to be bad, the dairy can find every pouch from it.