Analysis of the aroma intensities of volatile compounds released from mild acid hydrolysates of odourless precursors extracted from Tempranillo and Grenache grapes using gas chromatography-olfactometry

The odorants released by mild acid hydrolysis from an Amberlite XAD-2 odourless fraction of flavour precursors isolated from Tempranillo and Grenache grapes were studied in an aroma extract concentration analysis (AECA) experiment. Ninety-eight odour-active regions were detected in the AECA. The most important odorants released were unsaturated fatty acid derivatives, such as hexanal, octanol, 1-octen-3-one, E-2-heptenal, E,E-2,4-decadienal, fatty acids and several aliphatic lactones: γ-nona, -deca- and undecalactones, δ-decalactone and ε-dodecalactone (tentative identification). Some shikimic acid derivatives, such as guaiacol, 2-phenylethanol, ethyl dihydrocinnamate, ethyl cinnamate, 2,6-dimethoxyphenol, 4-vinylphenol, isoeugenol, phenyl acetic acid, and vanillin, were also important. By contrast, β-damascenone, 1,1,6-trimethyl-1,2-dihydronaphthalene (TDN) and an unknown were the only impact odorants derived from carotenoids, and farnesol and 3,7-dimethyl-1-ene-3,7-diol the only terpenols.