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What is the difference between Pasteurization and Sterilization?

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Pasteurization and sterilization are two methods of prolonging the life of food items by inactivating or killing microbes that would otherwise cause spoilage of food. However, there are a number of differences between the two.

Pasteurization is named after Louis Pasteur and is commonly used for food products, especially liquids. This method does not completely kill all the microorganisms, rather it makes them inactive and thus reduce the microbial load. The liquids, such as milk, are heated to a certain temperature (below the boiling point) and immediately cooled and sealed. 

In comparison, sterilization can be used not only for food items, but also for surfaces, medication, growth medium (for experimentation), etc. This method completely kills all the microorganisms (including bacteria, fungi, viruses, etc.). In this method, the material (to be sterilized) is heated to a high temperature, thereby killing all the microbes. This is a much harsher treatment than pasteurization. Apart from heat, sterilization can also be achieved by use of chemicals, radiation and pressure. 


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Pasteurization was developed by Louis Pasteur. Pasteurization is the process of heating foods such as milk yogurt, sour cream and ice cream to boiling for a set amount of time in order to reduce the populations of pathogenic microbes such as bacteria, viruses or other microbes. Because the temperature and time is set, the beneficial bacteria do not die, most proteins and other nutrients stay intact. Pasteurization allows foods to stay fresh longer due to the decreased populations of harmful microbes. 

Sterilization leaves no microbes living. Both beneficial and pathogenic microbes are eradicated. Sterilization is used in hospitals, laboratories, factories and day care centers where equipment and surfaces must be free off all microbes. Methods used for sterilization include, boiling, steam cleaning, radiation, chemical use.