What is Pasteurization?

Pasteurization was invented by French Scientist Louis Pasteur during the nineteenth century. Pasteur discovered that heating milk to a high temperature and then quickly cooling it before bottling or packaging it could keep it fresh for longer. The process was named after the French microbiologist, Louis Pasteur. Today, the process of pasteurization is widely used within the food and drink industry, and it is the most common form of heat treatment used on milk within Northern Ireland. Pasteurization makes sure milk is safe to drink (by killing any bacteria) and also helps to prolong its shelf life.
Pasteurization Process

Pasteurization Process

Pasteurisation is a mild heat treatment of liquid foods (both packaged and unpackaged) where products are typically heated to below 100 °C. The heat treatment and cooling process are designed to inhibit a phase change of the product. The acidity of the food determines the parameters (time and temperature) of the heat treatment as well as the duration of shelf life. Parameters also take into account nutritional and sensory qualities that are sensitive to heat.

In acidic foods (pH <4.6), such as fruit juice and beer, the heat treatments are designed to inactivate enzymes (pectin methylesterase and polygalacturonase in fruit juices) and destroy spoilage microbes (yeast and lactobacillus). Due to the low pH of acidic foods, pathogens are unable to grow. The shelf-life is thereby extended several weeks. In less acidic foods (pH >4.6), such as milk and liquid eggs, the heat treatments are designed to destroy pathogens and spoilage organisms (yeast and molds). Not all spoilage organisms are destroyed under pasteurization parameters, thus subsequent refrigeration is necessary.

Commonly Pasteurized Products

  • Beer
  • Canned food
  • Dairy products
  • Eggs
  • Milk
  • Juices
  • Low alcoholic beverages
  • Syrups
  • Vinegar
  • Water
  • Wines

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