Such features are crucial for setting up analytical strategies for detecting food frauds and adulterations by monitoring selected components within food matrices. The ever-growing use of mass spectrometry (MS) methodologies in food authentication and traceability originates from their unrivalled specificity, accuracy and sensitivity. The PSD spectrum of lactosylated β -CN (f1-28) 0P confirmed the loss of one lactose group ( m / z 3,140.2 Da) from the peptide (Fig. Moreover, the PSD spectrum of lactosylated β CN (f1-28) 4P yielded a neutral loss of 98 Da (H 3 PO 4 ), consistent with a peptide containing four phosphoserine residues (Fig. 5 exhibited a prominent neutral loss of 340 Da (one lactosyl group) from the precursor ion at m / z 3,802.9 Da. The degrees of phosphorylation and lactosylation of β -CN (f1-28) 4P were further confirmed by PSD MS experiments (Fig. Each peptide was a mono-lactosylated component. The results of CPP dephosphorylation are shown in Table 3 (Fig. The difference between the native and dephosphorylated peptide mass values allowed us to assign the phosphate groups correctly (one phosphate group 80 Da). To screen lactosylated CPP, in vitro dephosphorylation was carried out using ALP. In contrast, they are released in long-ripened cheese. α s1 -CN-derived CPP failed to form due to the internal location of the phosphorylation cluster. 3a), and intensely pasteurized milk (121 ☌ for 2 – 4 s, spectrum not shown). It was missing in raw, pasteurized (71.7 ☌ for 15 s Fig. In this manner, we identified the lactosylated β -CN (f1-29) 4P as a signature peptide of milk proteins and powdered milk preparations because it was missing in other types of milk. The native and lactosylated α s2 -CN (f1-21) 4P co-existed in milk powder. In all the milk samples, both native and lactosylated forms of CPP were detected, except in raw and pasteurized milk. Similarly, the major CPP were identified in the other commercial milk samples (ESM Fig. After enrichment on HA, only phosphorylated peptides were detected, as shown in Fig. This occurred probably because of the presence of active plasmin and somatic cell proteinases. Here was registered a substantial increase of peptides belonging to the β -CN, α s2 CN and α s1 -CN family. As an example, the MALDI spectrum for raw milk is shown in Fig. pasteurized, UHT, milk protein, and milk powder samples were examined by MALDI-TOF in the 1.2- to 5-kDa range.
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