Quantification of bovine α-lactalbumin in infant milk formula using LC-MS

α-Lactalbumin (α-la) provides essential amino acids to the diet and is therefore of nutritional importance. Bovine α-la is routinely supplemented to infant formulas, which makes it essential to obtain quantitative data of its content. In this study a quantitative, internally standardised Liquid Chromatography-Mass Spectrometry (LC-MS) method for bovine α-la in infant formula was validated, with good accuracy (90–110%) and precision (RSDRint < 7%). The specificity was high because the bovine α-la calibration samples were prepared with goat milk-based infant formula to avoid background of the endogenous bovine target peptide (CEVFR). Additionally, the method includes the qualitative monitoring of (i) a second confirmative tryptic peptide from the bovine α-la sequence (VGINYWLAHK), (ii) glycation of adjacent lysine residues and (iii) the presence of goat α-la adulteration in bovine infant milk formula. The methodology will be of importance to the dairy and infant formula industry in supporting bovine α-la label claims.