Changes in flavour and aroma compounds of ultra-high-temperature processed and aseptic-filled milk caused by storage conditions (temperature and duration)

The changes during a 4-month storage period at 5 or 25°C were investigated for sensory characteristics, volatiles and odorants of indirect (plate-type) ultra-high-temperature processed and aseptically filled milk. Quantitative descriptive analysis (QDA) showed that “plastic odour” and “smoothness” were stronger in the milk stored at 25°C for 2 and 4 months versus 5°C. Principal component analysis (PCA) of gas chromatography–mass spectrometry data revealed that the volatile profile change was larger at 25°C versus 5°C and that the storage duration at 25°C affected the volatile profile. Gas chromatography-olfactometry (GC-O) confirmed that similar changes were dependent on the storage temperature. A “coconut” odour contributed to the change in the odour profile. The QDA and GC-O results suggest that the increase in the “plastic odour” was a specific change associated with the 25°C stored milk and that (Z)-6-dodecen-4-olide, which had the strongest “coconut” odour, was related to the “plastic odour”.