Donkey milk is considered as an ideal substitute for human milk because of its high contents of whey protein, lactose, lysozyme, unsaturated fatty acids and vitamin C, and low contents of casein and fat. Additionally, donkey milk has various physiological functions, including hypoallergenic, bacteriostatic and anticancer activity. Thus, this review introduces readers to the nutritional composition of donkey milk, including proteins, amino acids, fats, minerals, vitamins., and compares it with that of human milk, bovine milk, buffalo milk, goat milk, and camel milk, in order to provide useful information for the comprehensive processing and utilization of donkey milk.

In this study, the effect of dual-enzyme hydrolysis on the allergenicity of the major proteins in skimmed milk was evaluated based on the degree of hydrolysis, molecular mass distribution, immunoglobulin G (IgG) binding capacity and allergic patients’ serum IgE binding capacity of hydrolysates. The results showed that after one-step hydrolysis for 80 min at an enzyme/substrate ratio of 3000 U/g and an Alcalase to Flavourzyme ratio of 3:1, the IgG binding capacity of casein, α-lactalbumin and β-lactoglobulinin in skimmed milk decreased significantly by 74.93%, 97.24% and 93.46%, respectively (P < 0.05).The advanced structure of proteins was damaged, leading to an increase in the α-helical and β-turn contents, and a decrease in the β-sheet content. In addition, the free sulfhydryl content increased significantly to 14.29 μmol/g (P < 0.05), the surface hydrophobicity also increased, and the structure became loose. The particles in skimmed milk were aggregated, causing the average particle size to increase significantly to 346.90 nm (P < 0.05) and reducing the stability of skimmed milk. The binding capacity to serum IgE from patients with milk allergy of the enzymatic hydrolysate decreased significantly by 23.53% (P < 0.05), and the overall allergenicity decreased significantly by 69.60% (P < 0.05). Therefore, dual-enzyme hydrolysis is an effective method to reduce the allergenicity of skimmed milk.

In order to clarify the differences in bovine milk fat globular membrane proteins during different lactation periods, milk fat globular membrane proteins in bovine colostrum and mature milk were characterized by quantitative proteomics. The differentially abundant proteins between the two groups were identified and analyzed by bioinformatics. A total of 763 proteins were identified in this study, of which 197 were shared by the two groups. Meanwhile, 80 differentially abundant proteins were further identified, of which, 41 were up-regulated while the rest were down-regulated (bovine colostrum/mature milk). Bioinformatics analysis of the differentially abundant proteins demonstrated that the main cellular components involving these proteins were exosomes, extracellular space, and extracellular regions. The main metabolic pathways involving them were metabolic pathways, purine metabolism, phenylalanine metabolism, tyrosine metabolism, pyruvate metabolism, and glycolysis/gluconeogenesis. Furthermore, 31 key proteins that could interact with other proteins were identified, including haptoglobin and 2-phospho-D-glycerol acid hydrolase. These findings will help to understand the changes of milk protein composition and its functionality during lactation, and lay the foundation for the deep processing of bovine dairy products.

To elucidate the differential milk fat globule membrane (MFGM) proteins between donkey colostrum (DC) and mature milk (DM), a comparative analysis was performed using proteomics. A total of 216 and 215 MFGM proteins were characterized in DC and DM, respectively. Among them, 15 differentially expressed and 25 specifically expressed MFGM proteins were identified. Bioinformatics analysis showed that the significantly differentially expressed MFGM proteins were mainly involved in cellular components including extracellular exosome, extracellular vesicle, and extracellular organelle compartments, and participated in biological processes such as external stimuli, cell proliferation, and blood vessel morphogenesis, and molecular functions such as metal ion binding, cation binding, and calcium ion binding. Additionally, these significantly differentially expressed MFGM proteins were mainly involved in metabolic pathways such as the complement and coagulation cascades and intestinal immune network for IgA production. Furthermore, some key protein factors with high connectivity, as determined by protein network interaction analysis, were identified as differently expressed MFGM proteins. This study provides a better understanding of the biological properties of donkey MFGM proteins and paves the way for future research of MFGM protein nutrition and for the development of formula milk powder.

This study aimed to analyze and compare the differentially expressed whey proteins (DEWPs) of donkey and bovine colostrum using high-performance liquid chromatography with tandem mass spectrometry-based proteomics. A total of 620 and 696 whey proteins were characterized in the donkey and bovine colostrum, respectively, including 383 common whey proteins. Among these common proteins, 80 were identified as DEWPs, including 21 upregulated and 59 downregulated DEWPs in donkey colostrum compared to bovine colostrum. Gene Ontology analysis revealed that these DEWPs were mainly related to cellular components, such as extracellular exosome, plasma membrane, and mitochondrion; biological processes, such as oxidation-reduction process, cell-cell adhesion, and small guanosine triphosphate (GTP) ase-mediated signal transduction; and molecular functions, such as GTP binding, GTPase activity, and soluble N-ethylmaleimide-sensitive factor (NSF) attachment protein receptor activity. Metabolic pathway analysis suggested that the majority of the DEWPs were associated with soluble NSF factor attachment protein receptor interactions in vesicular transport, fatty acid biosynthesis, and estrogen signaling pathways. Our results provide a vital insight into the differences between donkey and bovine colostrum, along with important information on the significant components as nutritional and functional factors to be included in infant formula based on multiple milk sources.