Differentiating ultra-high temperature milk and reconstituted milk using an untargeted peptidomic approach with chemometrics

An untargeted peptide profiling based on ultra-performance liquid chromatography quadrupole time-of flight mass spectrometry with chemometrics was performed to differentiate ultra-high temperature processed milk and reconstituted milk. Thirty-three marker peptides were identified, primarily released from the C- or N-terminal of beta-casein and alpha s1-casein. These peptides were produced by heating and protease hydrolysis. Additional heating and storage time experiments showed that the level of 18 marker peptides increased with heat load and storage time, whereas 15 peptides were solely influenced by heat load. The peptides from beta-casein showed higher sensitivity to thermal stress compared to those from alpha s1-casein. Additionally, eight modified peptides of casein were identified as indicators of milk thermal processing. The identified marker peptides can distinguish ultrahigh temperature processed milk and reconstituted milk, and are suitable for monitoring heating processes and storage of milk.