Feeling the pressure

摘要

Homogenisation is a method that has been used for almost 100 years in the dairy industry to make milk more stable by preventing fat separation, known as creaming, during storage. The principle of homogenisation involves pumping milk under pressure through two consecutive narrow orifices (stages) at around 50℃. Most of this pressure is released after the first stage and this, along with turbulent flow conditions' impact against the metal components of the homogeniser and high shear conditions, results in the disruption of molten globules of milk fat. The newly exposed fat globule surface is rapidly covered in surface active material, including milk casein micelles. The lower-pressure valve breaks up any clusters of globules that form at this point in the second stage.