Phenolic matrix effect on aroma formation of terpenes during simulated wine fermentation - Part I: Phenolic acids

In this study, fermentations were performed using simulated grape juice supplemented with terpene glycosides (TGs), extracted from Vitis vinifera L. Meili, and phenolic acids (gallic acid or p-coumaric acid). Free terpenes were detected using solid phase microextraction-gas chromatography-mass spectrometry (SPME-GC-MS) every day during the fermentation, and the aromas of final wines were evaluated by panelists. Quantum mechanical (QM) calculations performed at density functional level of theory were used to uncover the structural and thermodynamic properties of the binding between phenolic acids and free terpenes (or TGs). Results showed that phenolic acids remarkably inhibited TG hydrolysis and free terpene volatilization, and affected wine aroma perception. QM calculations revealed that phenolic acids can bind to linalool and its glycoside spontaneously (ΔG < 0) via hydrogen bonding and dispersive forces. These findings indicate that the matrix effect of phenolic acids can effectively control the release and modulate the global feature of wine aromas.