Influence of the food matrix structure on the retention of aroma compounds

The retention of the aroma compounds in a multicomponent medium like the fo od matrix is influenced by their affinity with the protein when lipid is pr esent at a low level (0.5%). The effect of the structure of the media is al so studied by using two media with the same composition; one was emusified, and the other was not. Among the studied aroma compounds, 2-nonanone and i soamyl acetate present opposite behaviors: the volatility of isoamyl acetat e is not affected by the change of the medium structure whereas that of 2-n onanone increases. The decrease of retention of 2-nonanone in an emulsified system would be due to a modification of the fixation site for this compou nd on the protein or to a competition between the lipid and the aroma compo und while the protein is adsorbed at the lipid-water interface.