Unraveling propylene glycol-induced lipolysis of the biosynthesis pathway in ultra-high temperature milk using high resolution mass spectrometry untargeted lipidomics and proteomics

In July 2022, the food safety accident that excessive propylene glycol was detected in milk processing factory raised widespread concerns about quality and nutrition of milk with illegal additive. To the best of our knowledge, the influences of propylene glycol to lipids in milk had not been systematically explored. Therefore, spatiotemporal distributions of lipids related to propylene glycol reaction and changes of sensory quality were investigated by food exogenous. Briefly, 10 subclasses (Cer, DG, HexCer, LPC, LPE, PC, PE, PI, SPH and TG) included 147 lipids and 38 pivotal enzymes were annotated. Propylene glycol altered lysophospholipidase and phospholipase A2 through altering structural order in lipids domains surrounding proteins to inhibit glycerophospholipid metabolism and initiated obvious changes in PC (10.45–27.91 mg kg−1) and PE (12.92–49.02 mg kg−1). This study offered insights into influences of propylene glycol doses and storage time on milk metabolism at molecular level to assess the quality of milk.