Dynamic changes in the volatiles and sensory properties of chilled milk during exposure to light

• Published in: International dairy journal Vol. 62; pp. 35 - 38
• Main Authors: Zardin, Erika, Silcock, Patrick, Siefarth, Caroline, Bremer, Phil J., Beauchamp, Jonathan
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01.11.2016
• ISSN: 0958-6946; 1879-0143
• DOI: 10.1016/j.idairyj.2016.07.005

Exposure 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.