Rapid detection and quantification of milk adulteration using MALDI-MS protein profiling and multivariate calibration

Abstract

The adulteration of high-value milks with low-value milks is a common fraudulent practice in the dairy industry. This not only results in economic or quality prejudice, but also poses a potential threat to individuals with sensitivities or allergies. Profiling the major whey and casein milk proteins can be a crucial tool in combating this malpractice, given that each mammal species exhibits a unique protein fingerprint. In this study, we employed matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-MS) as a rapid and straightforward method for profiling proteins from bovine, caprine, and ovine milks. Subsequently, we analyzed binary mixtures of goat and sheep milks with bovine milk to establish multivariate calibration models using partial least-squares (PLS) to quantify the adulteration of goat and sheep milks. Proteins were identified according to their molecular mass (Mr) and their intensities were considered as multivariate data. To achieve satisfactory calibration and validation results, normalization through variable augmentation was necessary, enabling the quantification of bovine milk across the entire adulteration range. This uncomplicated approach based on MALDI-MS protein profiling and PLS shows significant potential for qualitative and quantitative assessments of milk adulteration.