Influences of human milk proteins on the release of human milk odors: Non-covalent interactions between α-lactalbumin and key odor skeleton compounds

Abstract

Human milk (HM) provides optimal nutrition for infants, but infant formula (IF) serves as a potential alternative to HM when breastfeeding is not an option. However, IF possesses a more intense aroma than HM, and it is often challenging to reduce this disparity due to its stringent production regulations. Therefore, investigating the interaction between HM proteins and odor molecules is essential for comprehending the distinct odor characteristics of HM and guiding improvements in IF to mimic the aroma of HM. This research aims to characterize the HM odor and explore the influence of HM α-lactalbumin (HMLB) on the release of HM odor skeleton compounds (OSC) using a combination of computer simulation, human perceptions, and instrumental analyses. A total of 20 OSCs were identified. Notably, the release of most of these compounds was negatively correlated with the HM protein content, with the strongest negative correlations being observed for hexanal, nonanal, and decanal (|R| ≥ 0.7, P < 0.01). The molecular docking simulations demonstrated that HMLB inhibited the volatilization of hexanal, nonanal, and decanal, thereby increasing the odor threshold of these odor compounds (61.94 %, 241.5 %, and 198.6 %). This inhibition was mainly achieved through the formation of hydrogen bonding and hydrophobic interactions, a finding corroborated by multi-spectroscopic analysis. Overall, the experimental results provide valuable insights into the odor mechanism of HM and contribute to the development of IF that mimics the HM odor.