Abstract: Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), circular dichroism spectroscopy and matrix assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF/TOF-MS) were used to reveal the properties, structure and composition of milk powder protein from Dezhou donkeys, aiming to provide a basis for the deep exploitation of Dezhou donkey milk. The results showed that the protein content of the milk powder was 16.10%, the isoelectric point was evenly distributed between 4.5 and 6.5, and the molecular mass was mainly concentrated in the range of 10–20 and 53–78?kDa for whey protein, and 28–36?kDa for casein. By matching against the equine protein library, 386 proteins were identified, 139 of which were first discovered in donkey milk. This study provides a theoretical basis for revealing the physiological effects of donkey milk.

Key words: donkey milk powder, basic properties, structural characterization, protein fractions