Pasteurised

Pasteurised, or pasteurized, refers to the process of heating liquids or foods to a defined temperature for a specific time to kill or inactivate pathogenic microorganisms and spoilage enzymes. The aim is to reduce the risk of foodborne illness and extend shelf life while preserving most of the product’s quality.

Typical methods include low-temperature long-time (LTLT), high-temperature short-time (HTST), and ultra-pasteurisation (often called ultra-high-temperature, UHT). LTLT heats around 63°C for about 30 minutes; HTST uses about 72°C for 15 seconds; UHT involves roughly 135–150°C for 1–4 seconds to achieve shelf stability without refrigeration until opening. In dairy, pasteurisation is commonly followed by homogenisation to improve texture.

Historically, pasteurisation was developed in the 1860s by Louis Pasteur to combat spoilage and disease in wine and later in milk. The technique became a standard public health measure in many countries during the 20th century and remains widely used in food processing.

Impact and limitations: pasteurisation effectively reduces many dangerous organisms, including Salmonella, Listeria, and Escherichia coli, but it does not sterilise a product; heat-tolerant spores and some microorganisms may survive. Higher-heat processes like UHT can achieve commercial sterility. Nutritional and sensory changes can occur, particularly with prolonged heating. The method is routinely applied to milk and dairy products, fruit juices, and many prepared foods.

See also: food safety, thermal processing, sterilisation.