Changes of the volatile compounds and odors in one-stage and three-stage infant formulas during their secondary shelf-life.

The odor of infant formula changes due to alterations in its volatile composition during the shelf life. However, there is currently a lack of research on whether the odor changes in infant formula during the secondary shelf life, which refers to the period of repeated opening and usage in daily life. This study used headspace solid-phase microextraction (HS-SPME) coupled with gas chromatography-electrostatic orbitrap high-resolution mass spectrometry (GC-Orbitrap-MS) to investigate the volatile composition changes in one-stage and three-stage infant formulas during different stages (0 day, 3 days, and 7 days during the secondary shelf-life, i.e. simulated daily use). A total of 32 volatiles were identified, including nine aldehydes, seven ketones, four alcohols, three furans, two sulfur compounds, two esters, and five terpenoids. Of these, 16 compounds changed significantly in one-stage samples and 23 compounds in three-stage samples within 7 days of the secondary shelf-life. Further the odor of the three-stage infant formula samples was found changed substantially after 3 days of simulated use by using the triangle test. This study highlighted the considerable alterations in volatile compound composition and sensory changes during the simulated daily use and provided valuable insights for consumers in selecting and using infant formula products, as well as a new perspective for enterprises to improve the sensory quality of their products.