QSAR/QSPR approach of aroma compounds behaviour in food products

National audience

English. Fat and flavour are important factors in food acceptance and can affect the partitioning of hydrophobic flavour molecules. Most investigations on the release of flavour of fat-free yoghurts contain multiple thickeners. The addition of thickeners separately to fat-free yoghurt has not been extensively studied. For this reason, the aim of this work was to study the effects of different thickeners (starch and pectin) on the aroma release when added separately via a model fruit preparation to industrial fat-free yoghurt. After aromatisation of the yoghurt, and then a seven-day storage period, headspace analysis using solid phase micro extraction (SPME) was carried out. To evaluate the influence of the chemical structure of aroma compounds on retention/release equilibrium between vapour phase and dairy gels, we used QSAR approach in order to investigate the nature of involved interactions in complex food matrices. QSPR methods attempt to find relationships between the properties of molecules and an experimental response; the assumption is that changes in molecular properties elicit different responses. The QSPR study is intended to represent a physico-chemical property into a simple mathematical relationship, the QSAR equation: ER=f(p1, p2, p3, …pn) where ER is the experimental partition coefficient. Because of few number of data, our present aim consist merely to find simple linear relationships between experimental response and the aroma structure, reflected by molecular descriptor values, to identify some relevant structural properties related to the retentionand to propose a qualitative interpretation. We selected 20 descriptors that present at least a dependable correlation with a partition coefficient value. From obtained results, it appears that retention in fat-free stirred yoghurt containing 0.1% starch give preference to hydrophobic interactions, and existence of strong polarity disfavour retention is this medium. However, the role of some negative surface Jurs descriptors point out existence of the three types of van der Waals interactions: dispersion forces (London) and dipole-dipole interactions (Keesom and Debye). Interestingly, we observed that the retention of the most small and hydrophobic alcohols weakly depends on nature and amounts of thickener. More, Methyl-2-methybutyrate exhibits the same retention tendency as 1-Decanol, and the observed retention for most hydrophobic ester (Ethyl decanoate) is less affected by the nature of thickener as other esters (Ethyl hexanoate, Hexyl acetate, Ethyl octanoate). That put forward that retention/release properties are not determined by the chemical classes, but by an ensemble of chemical properties. In this way, QSPR approach constitutes a promising tool for characterising of interactions involved in complex food matrices.