What is Pasteurization?
Pasteurization: method of treating food by heating it to a certain point to kill pathogenic (disease-causing) organisms but does not harm the taste or quality of the food.
Milk is pasteurized by heating it to around 145°F (63°C) for 30 minutes or, using the «flash» method, heating it to 160°F (71°C) for 15 seconds, followed by rapid cooling to below 50 °F (10 °C), at what temperature it is stored.
Pasteurization is also used with beer, wine, fruit juices, cheese, and egg products. Fresh, unsqueezed fruit juices are a potential hazard, as some E. coli outbreaks have shown.
Named after the French chemist and biologist louis pasteur (1822-1895) who invented pasteurization, developed germ theory, founded the field of bacteriology, and created the first vaccines against anthrax and rabies.
Pasteur’s impact on medicine was so profound that his name remains attached, not only to pasteurization, but also to many other issues (the Pasteur effect, pasteurella, pasteurellaceae, pasteurellaceae infections, hemolytic pasteurella, pasteurella infections, pasteurella multocida, pasteurellosis , pneumonic, pasteurism; etc)
How pasteurization works
Food is processed with heat to kill the bacteria pathogenic Food can also be pasteurized using gamma radiation. Such treatments do not make food radioactive.
The pasteurization process is based on the use of one of the following time and temperature relationships.
High Temperature Short Term Treatment (HTST) : this process uses higher heat for less time to kill pathogenic bacteria. For example, milk is pasteurized at 161°F (72°C) for 15 seconds.
Low Temperature Long Time Treatment (LTLT) : this process uses less heat for longer to kill pathogenic bacteria. For example, milk is pasteurized at 145°F (63°C) for 30 minutes.
It is important to remember that times and temperatures depend on: (1) the type of food, and (2) the end result one wants to achieve, such as retaining nutrients, color, texture, and flavor of a food.
Processes used for pasteurized foods
Fast pasteurization: includes a high-temperature, short-time treatment in which pourable products, such as juices, are heated for 3 to 15 seconds to a temperature that destroys harmful microorganisms.
After heating, the product is cooled and packaged. Most beverage cases and pouches use this pasteurization method as it allows for extended unrefrigerated storage while still providing a safe product.
Steam pasteurization: this technology uses heat to control or reduce harmful microorganisms in meat.
This system passes freshly slaughtered beef carcasses that have already been inspected, washed and trimmed, through a chamber that exposes the meat to pressurized steam for approximately 6 to 8 seconds.
The steam increases the surface temperature of carcasses to 190° to 200°F (88° to 93°C). The corpses are then cooled with a stream of cold water.
This process has proven successful in reducing pathogenic bacteria, such as E. coli O157:H7, Salmonella, and Listeria, without the use of any chemicals. Steam pasteurization is used on almost 50% of American meat.
Irradiation Pasteurization: Foods, such as poultry, red meat, spices, and fruits and vegetables, are subjected to small amounts of gamma rays.
This process effectively controls vegetative bacteria and parasitic foodborne pathogens and increases the shelf life of food.
The effect of pasteurization on nutrients and flavor
Pasteurization can affect the nutrient composition and flavor of foods. In the case of milk, for example, high-temperature and short-temperature treatments (HTST) cause less damage to the nutrient composition and sensory characteristics of foods than long-term, low-temperature treatments (LTLT).
Other types of milk pasteurization
Ultrapasteurization – This involves heating the milk and cream to at least 280°F (138°C) for at least 2 seconds, but due to less stringent packaging, they must be refrigerated.
Milk shelf life is extended from 60 to 90 days. After opening, the decomposition times of ultra-pasteurized products are similar to those of conventionally pasteurized products.
Ultra-high-temperature (UHT) pasteurization – typically involves heating milk or cream to 280° to 302°F (138° to 150°C) for 1 to 2 seconds.
The milk is then packaged in sterile, hermetically sealed (hermetic) containers and can be stored without refrigeration for up to 90 days.
After opening, the decomposition times of UHT products are similar to those of conventionally pasteurized products.
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