Milk is an emulsion of fat globules in a watery fluid. Walstra was a world authority on how those fat globules behave in fluids and how to influence that behaviour. He took the dairy industry’s practical questions as the inspiration for basic research in physical chemistry and colloid science. For example, Walstra discovered what happens if you homogenize milk by making the fat globules smaller and how to get the globules to cluster together properly to make butter. Dairy studies had been around for a long time but it was professor Walstra who turned this into dairy science. ‘No other food product has been manipulated as much as milk’, says Tiny van Boekel, Walstra’s first PhD student and his successor as professor – although not in dairy science. ‘In the past, whey was a waste product in cheese-making but now it is almost more valuable than the cheese itself. Walstra laid the foundation for these kinds of applications.’ Walstra was professor of Dairy Science from 1982 to 1996. He was involved in setting up the Food Technology group, the collaboration between three chairs and the degree programme of the same name that started in 1970. Last year NZO, the association of dairy companies, set up the Pieter Walstra prize to encourage scientific research in dairy subjects.
Pieter Walstra, the man who founded dairy science
In the past milk was either full fat or semi-skimmed, but these days it is a raw material whose components are used in industrial applications. That transition is due to the scientific work of Pieter Walstra, Wageningen's last Dairy Science professor. He passed away on 29 May, aged 81.