Identification of aroma compounds and precursors of sour guava (Psidium friedrichsthalianum Nied.) following a sensomics approach

In this work, a sensomics approach was followed to determine the chemical constituents responsible for sour guava ( Psidium friedrichsthalianum Nied.) aroma. The odour-active volatiles were isolated by solvent-assisted flavour evaporation (SAFE) with dichloromethane. By application of the aroma extract dilution analysis (AEDA), ethyl butanoate and ethyl hexanoate, 3-sulphanylhexyl acetate (sulphury), and δ-dodecalactone (fruity) were identified with the highest flavour dilution factors among the 18 odour-active compounds. Quantitative measurements performed with the internal standard method allowed to calculate the odour activity values and revealed the important role of ethyl butanoate, ( Z )-3-hexenal, and ethyl hexanoate as key aroma compounds in this fruit. The sulphur compounds, dimethyl disulphide, 2-methyl-1,3-dithiolane, methional, 3-sulphanylhexyl acetate, 3-sulphanyl-1-hexanol, and bis(methylthio)methane, are reported here as sensory relevant odorants to the flavour of this fruit. The role of hexyl-β- l -glucopyranoside and 3-(1-hexanol)- l -cysteine as precursors of hexanol, and 3-sulphanyl hexanol, respectively, was demonstrated by enzymatic hydrolysis of corresponding precursor mixtures.