Mid-infrared spectroscopy can be applied to authenticate A2 milk

Area of Science:

• Dairy Science
• Analytical Chemistry
• Genetics

Background:

• A2 milk, differing from A1 milk by a genetic variation in beta-casein, is more digestible.
• This variation prevents the release of beta-casomorphin-7 during digestion.
• Authenticating A2 milk is crucial for consumers seeking easier digestion.

Purpose of the Study:

• To evaluate mid-infrared (MIR) spectroscopy for authenticating A2 milk in Holstein cows.
• To assess MIR spectroscopy as a rapid, noninvasive, and scalable method.
• To correlate spectral data with genetic variants and milk quality parameters.

Main Methods:

• Collected spectral, genetic (beta-casein, kappa-casein, beta-lactoglobulin), and milk quality data from 2,270 Holstein cow milk samples.
• Performed statistical analysis on milk composition and preliminary Principal Component Analysis (PCA) on spectral data.
• Developed a Partial Least Squares Discriminant Analysis (PLS-DA) model for A1/A2 milk authentication.

Main Results:

• Milk quality parameters were similar across protein fractions but varied slightly among farms.
• PCA could not effectively segregate A1 and A2 milk based on beta-casein genetics.
• PLS-DA achieved high balanced accuracy (up to 94% training, 88% testing) when classifying milk into A1 and A2 categories.

Conclusions:

• MIR spectroscopy, combined with PLS-DA, shows significant promise for authenticating A2 milk.
• This method offers a viable tool for routine, large-scale A2 milk verification.
• Further validation may enhance accuracy for specific genotypes.