Molecular profiling of triacylglycerols in bovine and goat milk powders via ultra-performance liquid chromatography-quadrupole time-of-flight mass spectrometry

Triacylglycerols (TAG) play several nutritional, technological, and functional roles in the dairy industry, representing approximately 98 % of milk fat. In the present study, the total fatty acid composition and the sn-2 fatty acid positional distribution of bovine and goat milk powders fat were analyzed by using the gas chromatographyflame ionization detector. Furthermore, the identification of TAG molecular species from milk powders was conducted using ultra-performance liquid chromatography coupled with quadrupole time-of-flight mass spectrometry (UPLC-Q-TOF-MS). The separation of milk TAG was accomplished by using isopropanol/acetonitrile (90:10, v/v) as mobile phase A, and water/acetonitrile (60:40, v/v) as mobile phase B. Myristic, palmitic, stearic, and oleic acids were identified as the most abundant fatty acids making up 11.55 and 10.71 %, 33.23 and 30.64 %, 10.86 and 12.52 %, and 26.74 and 21.80 % in the bovine and goat milk powders, respectively. In bovine milk, 221 molecular species of TAG were identified, with the predominant molecular species (LaCyO, CaLaPa, CyPaM, OCaCa, CaGCy, GLaCo) detected at a retention time of 6.362 min, with a relative abundance of 8.28 %. In goat milk, 202 molecular species were identified, with the major molecular species (CaLaM, CaPCa, CaCyS, CaCoAra, CaBuBe, LaPCy, LaCoS, LaBuAra, MPCo, MCyM, MBuS, PBuP, CyCoBe) detected at a retention time of 6.106 min, making up 8.14 % of the total TAG detected. These results provide valuable insights into milk fat composition for the dairy sector, aiding in the development of specialized dairy products.