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Dernière mise à jour : Mai 2018

Menu Logo Principal AgroParisTech Université Paris-Saclay

INRA GABI Unit

GABI : Génétique Animale et Biologie IntégrativeUnité Mixte de Recherche INRA - AgroParisTech

Mass Quant Milk : an original "protein profiling" method for the characterization of the protein fraction of milk

Mass Quant Milk: an original "protein profiling" method
© Inra
An original method for the characterization of the protein fraction of milk (identification and quantification of 6 major lactoproteins and their isoforms), using LC-MS, was developed. This method is offered as a reference method (ISO-IDF) and the basis for the conversion of MIR spectral data (average infrared), produced daily in dairy testing, into individual lactoprotein composition.

Context and stakes

Milk and dairy products remain today one of the most important sources of proteins in human nutrition. Dairy proteins and notably the caseins, figure among those elements that are quantitatively the most important in milk. Their nutritional quality has been shown and their health value is recognized. From a technological point of view, although the caseins were identified early on as the major determinants in cheese making aptitude of milk, the absence of reliable genetic markers prevents us from predicting cheese making aptitude. The development of an analysis method allowing for the qualification and quantification of individual proteins was therefore necessary before the study of the genetic variaibility of protein composition of milk could be undertaken on a large scale, providing the dairy industry the possibilty to increase the added-value and improve the technological properties of milk.

Results

As part of the R&D Phenofinlait project, by combining liquid chromatography (HPLC) and mass spectrometry, we were able to develop a reliable tool that provides the protein profile of milk in bovine, ovine and caprine species. This method, which is associated with a database where the theoretical masses of the major proteins, their known genetic variants, their splicing variants, phosphorylation, and glycosylation and some products of proteolysis (3000 masses for the bovine database were deposited by the Program Protection Agency) are recorded, allows for the identification and rapid and automatic quantification of the six main milk proteins and their isoforms. It provides the basis for the prediction of the protein composition of milk (6 major lactoproteins) from IR spectra produced by the instruments used in routine analysis in dairy control laboratories.

Perspectives

The finalization and qualification of this method which should allow direct quantification via mass spectrometry of the different variants and isoforms of the major lactoproteins, are elements necessary for the valorization and notably normalization of the method internationally (ISO/IDF-FIL). Since then the method has been extended to other species, notably the mouse, rabbit and camelids.

Valorization

The method was proposed by Rotterdam in June 2013 in front of a "standing committee" and was retained as the "Technical ISO/IDF standard".

The development and use of this method within the framework of a regional program aimed at evaluating cheese making aptitude of milk from Montbeliard cows in the AOP zone in Franche-Comté and the development of new tools to accompany farmers and laboratories in improving the cheese making aptitude, is a form of recognition of the high potential of this tool for the industry.