High hydrostatic pressure combined with high-temperature short time pasteurization improves the quality characteristics and extends the shelf life of donkey milk

Abstract

The processing method, which affects the quality and shelf life of dairy products, depends on the processing stability of raw milk. The effects of high-temperature short time pasteurization (HTST) at 75 °C/15 s and HTST plus high hydrostatic pressure (HHP) at 200, 300 and 400 MPa on the physical stability, soluble calcium and phosphorus concentrations, protein conformation and contents, and storage properties including microbiological characteristics, pH and sedimentation rate of donkey milk were investigated. HTST increased the particle size and lowered soluble calcium and phosphorus concentrations of donkey milk (P < 0.05). HTST plus HPP treatment at 200–400 MPa further increased the particle size and random coil, but decreased β-sheet and β-turn contents with the increasing pressure (P < 0.05). However, HTST plus HPP treatment at 400 MPa reduced the stability of the donkey milk. Moreover, HTST plus HPP treatment at 200–300 MPa preserved lysozyme, α-lactalbumin and β-lactoglobulin (P < 0.05). During the storage period, HTST plus HPP treatment at 300 MPa extended the shelf life by 85.71%, exhibiting stable pH and precipitation rate. It reduced the TMC, coliform and Staphylococcus aureus (P < 0.05). Therefore, our findings suggested HTST at 75 °C for 15 s plus HPP treatment at 300 MPa stabilizes the storage properties of donkey milk while maintaining quality characteristics.