In order to elucidate the difference in the composition of milk fat globule membrane proteins (MFGMP) in bactrian camel milk and bovine milk, the high-abundance MFGMP in the two milks were determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), two-dimensional electrophoresis (2-DE) and liquid chromatography-tandem mass spectrometry (LC-MS/MS). The experimental results showed that the most abundant protein fractions in bactrian camel and bovine MFGMPs were, in decreasing order, lactophilic lipoprotein (BTN), xanthine oxidoreductase/dehydrogenase (XO/XDH), milk agglutinin (MFG-E8 or PAS6/7), and adipocyte differentiation-related protein (ADRP or perilipin-2). The results of SDS-PAGE, 2-DE and LC-MS/MS were consistent for the high-abundance MFGMP fractions from bactrian camel milk and cow milk. The bactrian camel MFGMP identified by LC-MS/MS were subjected to Gene Ontology (GO) functional annotation analysis and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis, revealing that these proteins are mainly cell membrane, mitochondria and endoplasmic reticulum membrane components, involved in biological pathways such as translation and translation initiation, redox process, intracellular protein translocation, protein folding, and cellular redox homeostasis, and they have molecular functions such as binding activity and molecular catalysis.

A method using bovine β-lactoglobulin as the adulteration marker was developed for the qualitative and quantitative detection of cow milk in adulterated camel milk by ultra-high performance liquid chromatography (UPLC). The effects of different heat treatments on the adulteration marker were discussed to meet the need for the detection of different commercial camel dairy products. The results showed that this method could effectively detect milk in adulterated raw camel milk, pasteurized camel milk and camel milk powder. The regression equations of the three adulterated milk samples showed good linearity, with correlation coefficients (R²) of 0.9979, 0.9969 and 0.9978, respectively. The limits of detection for the adulterated samples were 2%, 3% and 5%, respectively, which could meet the detection requirements. Using this method, out of 10 different brands of commercial pure camel milk powder, four were found to be adulterated.

In this study, adulteration of bovine milk in fresh and thermally processed non-bovine milk was detected by SYBR Green and TaqMan real-time polymerase chain reaction (real-time PCR), and the effect of different heat treatment methods on the adulteration detection was explored aiming to meet the requirements for the detection of adulteration of different commercial non-bovine milk products. The results showed that the designed bovine-specific primers allowed specific amplification of DNA in bovine milk without cross-reactivity with DNA from non-target animals. The minimum detection limits of SYBR Green and TaqMan real-time PCR for bovine milk DNA were 1 and 10 pg, respectively, and both methods were capable of detecting at least 0.1% (m/m) bovine milk adulteration in non-bovine milk mixtures. The results of nine repeated experiments over three days confirmed high reproducibility of the methods. In addition, using the real-time PCR methods, bovine milk was detected in 7 out of 20 commercial non-bovine milk products, indicating high resolution and great practical application value of these methods.