Nanostructural and lipidomic alterations induced by sterilization: the unforeseen stability of ultra-high temperature (UHT)-treated yak milk fat globules

This research utilized a laser particle size distribution analyzer, stability analyzer, atomic force microscope, fluorescence spectrophotometer, and ultra – performance liquid chromatography - mass spectrometry instrument to compare the impacts of pasteurization (PAST), ultra - high temperature instantaneous (UHT) sterilization, and ultra - high pressure (UHP) sterilization on the structure and stability of yak milk fat globules (MFGs). The findings indicated that all three sterilization methods led to a reduction in the diameter of fat globules and damaged the edge structure of the milk fat globule membrane (MFGM). Nevertheless, the stability was enhanced through the reduction of Young's modulus and micropolarity of the MFGM, with UHT milk fat globules exhibiting the highest stability. Lipidomic analysis revealed a decrease in the phospholipid content in UHT milk and UHP milk, whereas the phospholipid content in PAST milk increased. Therefore, the yak milk system after UHT sterilization is the most stable. These data can contribute to the improvement of the quality of yak milk products and facilitate the further development and utilization of yak milk resources.