In 1864, a French man named Louis Pasteur discovered that liquids such as milk could be heated to a temperature slightly below boiling and held there for a set amount of time to eliminate the most harmful bacteria. The process of pasteurization is named after Louis Pasteur in recognition of his immense contribution to food safety and disease theory. Grocery stores carry a wide array of pasteurized goods including milk, juices, non-dairy milks, and other similar food products. Many nations require that foods be pasteurized for safety.
Pasteurization relies on the principle that most harmful bacterial can be killed by heat. The most effective way to kill bacteria is boiling, but this compromises the flavor of the liquid. Pasteurization strikes a happy medium, keeping the flavor delicious while making the food safer. In addition to minimizing the risk of sickness, pasteurization also makes foods more shelf stable and less likely to rot, meaning that fresh dairy products and juices are available to more people.
There are two primary methods of pasteurization: the liquid can be heated to 145 degrees Fahrenheit (63 degrees Celsius) and held there for at least thirty minutes, or the liquid can be flash pasteurized at 161 degrees Fahrenheit (72 degrees Celsius) for a minimum of 16 seconds. Pasteurization can be done using a continuous method, where the liquid flows through a pasteurization system, or by using a batch method, where one batch of the liquid is pasteurized at a time. Continuous pasteurization is popular for large producers, because it does not slow the supply line as much as batch pasteurization does.
Pasteurization must be performed on clean equipment. If bacteria is introduced after the liquid has been pasteurized, it can colonize it and potentially cause an outbreak of food borne illness. For this reason, companies which perform pasteurization are subject to frequent inspections to ensure that the equipment they are using is safe, and that the liquids they are pasteurizing are being handled correctly.
After pasteurization, bacteria can still appear. It is important that foods be safely handled and stored at every step of the supply process from animal, fruit or vegetable to stomach. In most cases, after food is pasteurized it should be refrigerated. The food is held in refrigeration until it is shipped out in cooled trucks to grocery stores, which store the food under refrigeration until consumers purchase it. Home consumers are responsible for following directives regarding temperature to ensure that the foods they are consuming are safe.