Determination of storage stability of butter enriched with unsaturated fatty acids/conjugated linoleic acids (UFA/CLA) using instrumental and sensory methods

The oxidative stability of butter enriched with unsaturated fatty acids and conjugated linoleic acids (UFA/CLA butter) was evaluated by chemical, sensory and microbiological analyses during 8 weeks of storage at 6 °C and compared with that of conventional butter. The odour-active compounds were analyzed by gas chromatography–mass spectrometry combined with olfactometry, using solid phase microextraction. Olfactometric analysis showed that both, fresh UFA/CLA butter and fresh conventional butter had similar aroma profiles. After 6–8 weeks of storage, UFA/CLA butter showed stronger fatty (butanoic and 3-methyl butanoic acid), metallic [(E,E)-2,4-nonadienal], green [(E)-2-hexenol] and creamy (2-pentanone) notes compared with the conventional samples. A sensory panel described the two fresh butter types as having a similar sensory profile, except for a stronger creamy aroma, a less intense cooked milk aroma and a significantly higher spreadability of the UFA/CLA butters. Sensory descriptive analysis showed also that both butter types aged in a very similar way, with an increase in rancid and oxidized notes.