Zardin, E.E.ZardinSilcock, P.P.SilcockSiefarth, C.C.SiefarthBremer, P.J.P.J.BremerBeauchamp, J.J.Beauchamp2022-03-052022-03-052016https://publica.fraunhofer.de/handle/publica/24683310.1016/j.idairyj.2016.07.005Exposure of milk to light causes photo-oxidation and off-flavour generation. To characterise these reactions, semi-skimmed (1.5% fat) and whole (3.8% fat) extended shelf-life cows' milk were exposed to light for 20-48 h at 4 °C and volatiles in the milk headspace were measured on-line using proton-transfer-reaction mass spectrometry (PTR-MS). The flavour of the whole-milk was assessed by aroma profile analysis on both orthonasal/retronasal odour and taste after 0, 0.25, 1, 6 and 24 h light-exposure. Sensory changes perceived in milk exposed to light for up to 6 h varied in intensity and between replicates, most notably a transient sensory defect being detectable after 0.25 h exposure, but these changes did not correspond to any volatile organic compound (VOC) generation detected by PTR-MS. After 24 h, several compounds showed enhanced release profiles. Principal components analysis related these VOCs to changes in the sensory properties of the milk, described as oxidised/rancid/hay-like.en637journal article