W.L.P. Bredie and MA. Petersen (Editors) Flavour Science: Recent Advances and Trends © 2006 Elsevier B.V. All rights reserved. The role of lipids in aroma/food matrix interactions in complex liquid model systems Celine Riera, Elisabeth Gouezec, Walter Matthey-Doret, Fabien Robert and Imre Blank Nestle Research Center, Vers-chez-les-Blanc, 1000 Lausanne 26, Switzerland ABSTRACT The release of nine aroma compounds was investigated in complex liquid bouillon-type model systems containing various non-volatile constituents. The relative release was determined by static headspace GC-MS as a function of the bulk composition. Among the non-volatile food constituents studied, fat appeared to be very efficient in binding volatile aroma molecules. This retention by the fat was directly correlated with the intrinsic physical properties of the aroma compounds, such as the water/octanol partition coefficient. The individual effect of the major fat constituents was studied as well, indicating that, for example, even small amounts of phospholipids may effectively retain volatile compounds. 1. INTRODUCTION The phenomena related to aroma release and retention have become a widely studied research field [1,2]. Despite the high complexity of food, most of the work published so far is dealing with rather simple systems studying the release of volatile compounds as affected by selected food biopolymers, such as starch [3], xanthan [4], carrageenan [5], pectin [6], and p-lactoglobulin [7]. Also lower molecular weight compounds of different chemical classes were studied, in particular lipids, which notably affect flavour release by lowering the vapour pressure of many odorants and changing the time scale of release with varying concentrations [8]. Reduction of fat content in food results in a drastic shift of the overall flavour profile leading to different odour sensation, even if the changes in the fat content are small [9]. The affinity of flavours to the lipid phase depends on its chemical composition, chain length, degree of saturation, and sequence of fatty acids in the triacylglycerol [10].