Sorption and Interaction of the Flavonoid Naringenin on Tomato Fruit Cuticles

The flavonoid naringenin accumulates in tomato fruit epidermis during ripening. The sorption of this flavonoid to enzymatically isolated cuticles of Solanum lycopersicum was studied as a function of the temperature and naringenin concentration at two stages of fruit growth. The selected stages were mature green, without flavonoids in the cuticle, and ripe tomato, with significant amounts of flavonoids in the cuticle. Sorption isotherms showed different behaviors that could be explained in terms of different affinities of the sorbed flavonoid for the cuticular matrix. The partition coefficient of naringenin in the system cuticle/water solution was a function of temperature and concentration. Changes in the free energy, enthalpy, and entropy for the phase transfer of naringenin to cuticle were also calculated, indicating the existence of naringenin−naringenin interactions replacing naringenin−cuticular matrix interactions at high concentrations with the final result of solid precipitations in the form of clusters within the cutin matrix.