Release of aroma compounds in binary and ternary carbohydrate model systems.

The release of volatile compounds from food matrices is governed by kinetic and thermodynamic phenomena; both of them are affected by several compositional and environmental factors. Simple model systems are in general used to evaluate the impact of a single chemical (e.g. composition) or physical properties (e.g. viscosity) on the kinetics of the aroma release, especially in the case of saccharides. This study is thus, aimed to evaluate the release kinetics of aroma compounds added to binary and ternary model systems made with disaccharide and maltodextrins and the effects of their physical (viscosity) and physico-chemical (in particular, aw) properties.Sucrose (S), trehalose (T) and Maltodextrines (MD, DE 7-9) were used in different concentrations to make up binary (water-sugar, S or T) and ternary (water-sugar-maltodextrin) model systems. Moreover, the ternary systems were prepared to keep the same molarity of the disaccharide as in the correspondent binary system. A mix of 4 esters at different molecular weight and hydrophobicity (ethyl acetate-EA, ethyl butirate-EB, isopentyl acetate-IA, and ethyl hexanoate-EE) were added in the model system to achieve a final concentration in the solution of 0,01% v/v for EA, EB and IA and 0,005% v/v for EE. The kinetic curves of the release of the volatiles up to the equilibrium were evaluated by gas-chromatografic analysis. The initial apparent rate of release, Rappi (min-1) of each aroma compound was computed in agreement to Seuvre et al. (2007) as well as to Anese et al. (1999). The latter model allowed to determine the a kinetic index of the release in the gas phase (d) of the aroma compounds in the various model systems.Binary model systems made with disaccharides with a concentration up to 50% of solute vary their aw values from 0.999 to 0.946 and 0.950 for T and S. The presence of MD in the ternary systems did not meaningfully affected the water activity of the binary system made with the same sugar whilst it significantly increased their viscosity. The kinetics of the aroma release resulted to be influenced differently by the nature of the aroma compound, the molecular complexity and concentration of the saccharide as well by the viscosity and water activity of the model systems. In binary solutions made with increasing concentration of T or S, where limited aw decrease and viscosity increase occurred, only EE and EA showed a slower release rates, while EB and IA were not affected. On the other hand, binary systems made with increasing concentration of MD besides a negligible aw change showed a significant decrease in the release rate. In ternary model systems in presence of both the saccharide and MD, competitive and/or synergic effects occurred and it differently increased or decreased the rate of the aroma release.Anese M. et al. (1996). In Ricerche e innovazioni nell’industria alimentare. Vol. 2 Chiriotti Editore, Torino, 891-899.Seuvre A-M. at al. (2007). Food Research International 40, 480-492.[...]