Gas chromatographic–olfactometric characterisation of headspace and mouthspace key aroma compounds in fresh and frozen lamb meat

Two different techniques for obtaining extracts representing the most relevant aroma chemicals from grilled lamb have been developed and applied to the elucidation of the gas chromatographic−olfactometric (GC−O) profiles of grilled lamb from fresh or frozen samples. The first technique attempted to collect the aroma released during grilling; and the second one, the aroma released during eating. The GC–O work was complemented with a thorough isolation and identification study comprising liquid chromatography and dual gas chromatography with simultaneous MS and olfactometric detection. Eight different aroma compounds with meaty odours were detected of which (Z)-2-heptenal, 2,5-dimethylpyrazine, (Z)-2-decenal, 2-butyl-2-octenal, 2-acetyl-2-thiazoline and (E,E)-2,4-decadienal could be identified. Moreover, 2-isopropyl-3-methoxypyrazine, 2-methylbenzaldehyde and 4-hydroxy-3-methoxybenzaldehyde (vanillin) were described for the first time in lamb. Frozen samples contained higher levels of ethyl hexanoate and butanoic and 3-methylbutanoic acids, while samples obtained directly from the grill were richer in pyrazines. Furaneol was only important in samples directly collected from the mouth.