Quantitative determination of odour-active volatiles exhibiting FD higher than 32, was done by internal standard method in the DB-5ms column. For that purpose, 2-isopropyl-5-methylphenol was added as internal standard, together with a defined mixture of the respective analytes, to 50 mL of distilled water, and pro- cessed by using the same procedure presented above in Section 2.3. Calibration curves were constructing using a series of solutions of varying nominal concentrations containing each analyte, where the slope was assumed as the response factor. An identical amount of internal standard was added to each solution and the corre- sponding chromatograms obtained (IOFI, 2011). All data were ob- tained in triplicate.