Flavour profiling by gas chromatography-mass spectrometry and sensory analysis of yoghurt derived from ultrasonicated and homogenised milk

The odour, flavour, taste, sensory and volatile components profile of yoghurt, derived from milk homogenised by ultrasound or pressure were compared. The ultrasonication of milk led to yoghurts with lower degree of likeness (DOL) and off-flavours compared with those of yoghurts from pressure treated milk; also, burned, pungent and fatty flavour characteristics were more intense. The volatile components were identified by solid phase microextraction-gas chromatography-mass spectrometry (SPME-GC-MS). Both homogenisation treatments lead to chromatograms with similar peak areas of 2,3-butadione, 3-hydroxy-2-butanone, delta-decalactone, while the chromatogram peak areas of acetone, 2-butanone, 2-heptanone, bicyclo[2,2,1]-heptan-2-one, 2-nonanone, 2-undecanone, butanoic acid, hexanoic acid, octanoic acid, n-decanoic acid, hexadecanoic acid, acetaldehyde, hexanal, 1-buten-3-yne, heptane and dimethylsulphide were higher for the ultrasonicated samples. Sensory characteristics and GC-MS profiles were correlated with DOL and two models created with PLS regression. Both models included the appropriate variables and showed adequate ability to describe DOL by sensory characteristics or volatile components.