Switchable GC/GC × GC–olfactometry–mass spectrometry system for the analysis of aroma components of infant formula milk-based on cow and goat milk

The study sought to characterize the composition of volatile compounds and key aroma-active compounds of infant formulas (IF), which derived from cow's milk and goat's milk. The volatile aroma compounds were analyzed by the solid-phase microextraction (SPME) combined with a new switchable GC/GC × GC–olfactometry–mass spectrometry (SGC/GC 2 -O-MS) system, which can switch between one-dimensional and two-dimensional analysis modes and can realize the sniffing function under two-dimensional analysis conditions. The key aroma-active compounds were analyzed by the aroma extract dilution analysis (AEDA) and odor activity value (OAV). A total of 118 volatile compounds were identified in IF samples from 12 brands, of which 66 had aroma activity. These results revealed that hexanal had the highest FD factor but was not responsible for the difference between GS and CS. According to the results of OPLS-DA and VIP, it was helpful to screen for more important volatile compounds. ( E )− 2-octenal, ( E,E )− 3,5-octadien-2-one, (E,E )− 2,4-decadienal, 3-methylbutanal and 2-pentylfuran helped distinguish GS from CS. • The switchable GC × GC-O-MS system is applied for the aromas of IF. • The content of aldehydes in IF is higher than other compounds. • AEDA analysis found that the FD factors of many odor-active compounds are 8–32. • The odorants with high FD factors in CS are different with GS.