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 chromatography-flame 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.