The taste of future foods: molecular insight into plant protein and flavour binding

Plant proteins have gained attention to be used as healthier ingredients in new food applications. However, indigenous off-flavours, such as bitterness and astringency, reduce consumer liking and acceptability of plant-based food products. To tackle this concern often flavour addition is seen as a solution. Nevertheless, proteins can interact extensively with flavour molecules that can bind the protein´s binding sites, thus affecting their release. As a result, overall flavour perception is disrupted. Therefore, this study aims to unravel the drivers of the binding mechanism at the molecular level, and determine how the chemical structure of both aroma molecules and proteins has an impact on the interactions with plant proteins and thus, on aroma release and retention. Hence, we hypothesize that size and shape of aroma molecules may influence the strength, nature and behaviour of these interactions. In the current preliminary study, binding to PPI (1%) capacity increased by enlarging the chain length of ketones, which is related to hydrophobic interactions. Exponential growth by 1.5% is observed when adding an extra carbon atom to the ketone molecules. A flavour chemical structure with an extensive number of carbon atoms and thus, long carbon chains, will lead to the existence of more binding sites and lastly, to a higher binding tendency. Besides, binding to PPI (1%) decreased in the following order: trans-2-nonenal (95%)>nonanal (85%)>2-nonanone (52%). The location of the functional group at the end of nonanal resulted in a higher binding as compared to the functional group located more in the middle of the structure (2-nonanone). This is partly explained by an occurring reaction of the alkenal double bond with lysine and histidine residues. Sensory studies will be carried out to investigate the impact of aroma retention on the dynamics of in-vivo aroma release, thus to acquire a complete picture of the flavour molecules engaged in the binding mechanism.