Examining the validity of a new rapid method for mapping out proteins in milk

Abstract

Milk protein compositions play a pivotal role in physicochemical and technological properties of milk, particularly in rennet coagulation in cheese production. Conventional analytical methods such as sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and liquid chromatography–high resolution mass spectrometry (LC-HRMS) provide detailed protein characterization but require long analysis times, extensive sample preparation and specialized instruments. Therefore, a need for another rapid method for practical routine protein profiling in dairy applications.
The aim of this study was to validate microfluidic chip electrophoresis using the Agilent 2100 Bioanalyzer and Protein 80 kit as a rapid method for milk protein profiling and to investigate if protein profiles obtained by this technique are correlated with rennet-induced coagulation properties. Raw milk samples collected from seventeen dairy farms and four dairy plant silos in southwestern Sweden were analysed. Protein profiles obtained by the Bioanalyzer were compared with LC-HRMS data, and relationships between protein fractions and rheological parameters were evaluated.
The Agilent 2100 Bioanalyzer successfully detected and profiled the major milk protein fractions, including α-casein (α-CN), β-casein (β-CN), κ-casein (κ-CN), β-lactoglobulin (β-LG), and α-lactalbumin (α-LA). Good reproducibility was observed for the major protein peak and overall protein distribution patterns showed agreement with LC-HRMS. However, differences were observed for certain protein fractions, particularly proteins with overlapping peaks and post-translational modifications.
Correlation plots revealed moderate relationships between casein fractions and rheological properties. Among the caseins, κ-CN showed the strongest association with yield stress, suggesting a potential contribution to gel network formation during rennet coagulation. Nevertheless, this indicated that milk coagulation behaviour is influenced by multiple factors beyond protein composition alone.
This study is managed within the PhD project “From farm to dairy: Sustainable milk quality for profitable cheese production” by Simon Höxter. By validating this rapid protein profiling technique and correlating its relationship to coagulation properties, this thesis contributes to the development of more efficient measurement for characterizing milk quality in industrial cheese production.
To summarize, microfluidic chip electrophoresis using the Agilent 2100 Bioanalyzer demonstrates potential as a rapid and reproducible method for milk protein profiling. Although further experiments are required before the method can be considered fully suitable for quantitative protein analysis, its speed, automation, and low sample requirements make it a promising screening tool for dairy research and industrial applications.

Popular Abstract

Milk contains different proteins that are important for making dairy products. The amounts of different types of proteins present in milk can affect how well milk coagulates and therefore affect how efficiently cheese can be produced. Dairy industries are in search of more rapid and reliable methods to analyze milk proteins. However, many current laboratory techniques are expensive, require highly specialized equipment and can take a long time to analyse.

This project investigated whether microfluidic chip electrophoresis could be used to analyze milk proteins as a new protein analysis method. The method was performed using an Agilent 2100 Bioanalyzer, an instrument that separates proteins according to their weight and produces a protein profile within a short time. Milk samples were collected from Swedish dairy farms and silos were analysed and compared with results from LC-HRMS, a common advanced protein analysis method.
The results showed that the Bioanalyzer could successfully detect the major milk proteins and generate repeatable protein profiles while requiring only small sample volumes and limited preparation. The method was much faster than advanced mass spectrometry techniques and therefore has potential for screening large numbers of milk samples. However, it was less precise when distinguishing proteins that have very similar structures or molecular weights.
The study also explored whether differences in protein composition were related to milk coagulation properties that are important for cheese production. Some relationships were observed, particularly for κ-casein, a protein known to play an important role in curd formation. Nevertheless, protein composition alone could not fully explain differences in coagulation behaviour between milk samples.
In conclusion, the Agilent 2100 Bioanalyzer is not yet a replacement for advanced analytical methods such as LC-HRMS. However, it shows strong potential as a rapid and practical tool for routine milk protein screening in the dairy industry where fast results and high sample throughput are important.

• author: Zi, Yu and Nguyen, Khanh Minh Mai
• supervisor: Frida Lewerentz; Simon Höxter
• organization: Food Technology and Nutrition (M.Sc.)
• alternative title: Utvärdering av en ny tidseffektiv metod för profilering av mjölks proteinkomposition
• course: KLTM02 20261
• year: 2026
• type: H2 - Master's Degree (Two Years)
• subject: Agriculture and Food Sciences; Technology and Engineering
• keywords: Milk proteins, HPLC, Microfluidic chip electrophoresis, Protein profiling, Milk coagulation, Cheese production, Food Engineering Nutrition and Food Chemistry
• language: English
• id: 9230472
• date added to LUP: 2026-06-16 13:11:34
• date last changed: 2026-06-16 13:11:34