Pasteurization is a method of food preservation in which pathogens are removed and shelf life is increased by treating packaged and unpackaged foods (such milk and fruit juices) with mild heat, typically to less than 100 °C (212 °F). Although most bacterial spores survive the process, it is meant to kill or inactivate microorganisms and enzymes that contribute to food deterioration or disease risk, including vegetative bacteria. The procedure is called Louis Pasteur in honour of the French microbiologist whose work in the 1860s showed that thermal processing might destroy undesirable germs in wine. Pasteurization also inactivates spoilage enzymes. To achieve food preservation and food safety, pasteurisation is now widely employed in the dairy industry and other food processing industries. By 1999, the majority of liquid products had been heated in continuous systems, either directly or indirectly utilising hot water and steam, plate heat exchangers, or both. The nutritional value and sensory qualities of the foods are slightly altered as a result of the low heat. Other non-thermal pasteurisation techniques include paulization, high pressure processing, and pulsed electric field.