1285 Research Article Received: 23 December 2008 Revised: 23 June 2009 Accepted: 25 June 2009 Published online in Wiley Interscience: 18 March 2010 (www.interscience.wiley.com) DOI 10.1002/jsfa.3929 Retention of aroma compounds: an interlaboratory study on the effect of the composition of food matrices on thermodynamic parameters in comparison with water Mirela Kopjar, a–d Isabelle Andriot, a–c Anne Saint-Eve, e Isabelle Souchon e and Elisabeth Guichard a–c * Abstract BACKGROUND: Partition coefficients give an indication of the retention of aroma compounds by the food matrix. Data in the literature are obtained by various methods, under various conditions and expressed in various units, and it is thus difficult to compare the results. The aim of the present study was first to obtain gas/water and gas/matrix partition coefficients of selected aroma compounds, at different temperatures, in order to calculate thermodynamic parameters and second to compare the retention of these aroma compounds in different food matrices. RESULTS: Yogurts containing lipids and proteins induced a higher retention of aroma compounds than model gel matrices. The observed effects strongly depend on hydrophobicity of aroma compounds showing a retention for ethyl hexanoate and a salting out effect for ethyl acetate. A small but noticeable decrease in enthalpy of affinity is observed for ethyl butyrate and ethyl hexanoate between water and food matrices, suggesting that the energy needed for the volatilization is lower in matrices than in water. CONCLUSION: The composition and complexity of a food matrix influence gas/matrix partition coefficients or aroma compounds in function of their hydrophobicity and to a lower extent enthalpy of vaporization. c  2010 Society of Chemical Industry Keywords: aroma compounds; partition coefficient; retention; food matrix INTRODUCTION Acceptability of foods by consumers is highly governed by their organoleptic properties. Aroma perception is mainly related to the release in the gas phase of aroma compounds present in the food. However, food products are very complex matrices because of their chemical composition and structure. The nature and amount of different components such as proteins, lipids and carbohydrates greatly influence aroma release and perception. 1,2 Understanding the behavior of aroma compounds, the strength and the nature of interactions between aroma compounds and ingredients of food matrix is thus of major significance for improving the overall aroma and thus the quality of food products. The influence of different types of proteins on aroma com- pounds release has been widely studied, pointing out the existence of molecular interactions, ionic bonding, hydrogen bonding, and hydrophobic bonding. 3–5 As most of the aroma compounds are hydrophobic, the presence of lipids influences partitioning of aroma compounds between oil and aqueous phase and conse- quently between matrix and gas phase. 6 The effect of fat on the retention of hydrophobic aroma compounds is higher than that of proteins. 7 Moreover, the retention of aroma compounds in emulsions depends not only on the amount of fat but also on the composition of the fat. 8 Carbohydrates can also lead to the reten- tion of aroma compounds in the matrix. For example, starch and more precisely amylose can form complexes with specific aroma compounds. 9–11 Other types of carbohydrates such as pectin can play an important role in aroma compound retention due to their thickening effect, which reduces aroma diffusion. 12–14 ∗ Correspondence to: Elisabeth Guichard, INRA, UMR 1129 FLAVIC, 17 Rue Sully, F-21000 Dijon, France. E-mail: guichard@dijon.inra.fr a INRA, UMR 1129 FLAVIC, F-21000 Dijon, France b ENESAD, UMR 1129 FLAVIC, F-21000 Dijon, France c Universit´ e de Bourgogne, UMR 1129 FLAVIC, F-21000 Dijon, France d Faculty of Food Technology, F Kuhaca 18, HR-31000 Osijek, Croatia e UMR 782 GMPA, INRA-AgroParisTech BP 1, F-78850 Thiverval-Grignon, France J Sci Food Agric 2010; 90: 1285–1292 www.soci.org c  2010 Society of Chemical Industry