How is fat content in dairy products determined?

Milk and milk products are subject to strict analytical controls during processing and handling to guarantee their composition and quality. Commission Implementing Regulation (EU) 2018/150 of 30 January 2018 laid down rules for the analysis and quality evaluation of milk and milk products eligible for public intervention and aid for private storage. One of the most important factors when evaluating milk and milk products is the fat content:

• Fat content has a direct impact on the price per liter of milk
• Fat content is used to determine if the milk or cheese products comply with statutory limits
• Fat content is used to classify milk for the production of dairy products

Methods for determining fat content

There are various methods to determine the fat content in milk and cheese products. The 2 most common methods are:

1. The Mojonnier method

The Mojonnier method is a gravimetric method that uses organic solvents (e.g. diethyl ether) to extract the fat. The solvent is evaporated and the fat content is determined by weighing the dry fatty extract.

2. The Gerber method

The Gerber method is a volumetric method that uses chemical reagents (e.g. sulphuric acid, detergents) to dissolve the protein that encapsulates the butterfat (fat globule membranes) and separate the fat. The fat content is measured with a special glass flask called a butyrometer.