The carrier gas was helium with a flow of 1 mL/min. The temperature programmed was isothermal at 40 °C for 10 min, and then it was raised at 5 °C/min to 240 °C and held for 11 min. The GC–MS transferline temperature was at 280 °C. The MS operated in electron impact mode with electron impact energy of 70 eV, and collected data at a rate of 0.7 scans/s over a range of m/z 40–650. The compounds were identified by comparison with commercial reference compounds provided by Sigma-Aldrich (St. Louis, MO) and by comparison of their mass spectra with those contained in the NIST and Varian libraries. Volatile compounds were classified according to their most probable origin: lipid oxidation (L), Maillard reaction (M), and other reactions/sources (O). Due to the difficulties to classify all compounds, volatiles with unknown origin were marked as follows (−).