Comparation of aroma-active compounds in fresh commercial infant formula and the change during ambient storage

1. The PCA and heatmap showed that the 14 brands of infant formula were classified into 3 groups according to aroma-active compounds. 2. Hexanal was the aldehyde that changed the most after storage in infant formula. 3. Among the ketones, (E,E)-3,5-octadien-2-one showed the greatest change after storage. 4. YL and YP-Q brands had the richest content of aroma-active compounds. This study compared the aroma-active compounds in 14 brands of commercially infant formula and investigated their changes during ambient storage after opening for 2 months. A total of 29 major aroma-active compounds were detected in infant formula. From the PCA and heatmap analysis, a total of 14 brands of infant formula were classified into 3 groups, the second group contained JLB-Y, AY and FH-F, of which 2-furanmethanol and (E,E)-3,5-octadien-2-one were mainly compounds, the third group contained YL and JLB-L, the characteristic flavor compounds in this group were mainly hexanal, heptanal, etc. Aldehydes, as the main volatile substances, account for more than half of the total volatiles. Nearly half of the aldehydes showed more significant changes after storage, e.g. hexanal, octanal, (E)-2-octenal and 3-methylbutyraldehyde. The YL and YP-Q produced more saturated aldehydes after storage, the concentration of hexanal in YL-2m and YP-Q-2m was 2138.5 μg/kg and 2004.1μg/kg, respectively. The concentrations of heptanal, octanal, and nonanal also increased relatively significantly, which may lead to a distinct rancid flavor in YL and YP-Q. Besides, among the ketones, (E,E)-3,5-octadien-2-one showed the greatest change after storage, especially in JLB-L. According to sensory evaluation experiments, the milky flavor of infant formulas decreased and fatty, rancid, fishy and grassy flavors were found to have increased to different extents after storage. The current information gap on the concentration and evolution of volatile compounds in commercially available infant formula is filled by this study.