Volatile organic compounds in milk and mozzarella: comparison between two different farming systems

The Volatile Organic Compounds (VOC) and sensory characteristics of milk and mozzarella from farms with different rearing systems were compared. Milk samples were taken from 9 intensive (INT) and 13 semi‐extensive farms (EXT) in the grazing period. VOC were analysed by SPME‐GC‐MS, sensory evaluation was carried out by paired comparison. The volatile profiles of milks were significantly different: acetone and isopropyl alcohol characterized INT milk, pentanoic and decanoic acids, hexanal, ethylacetate, toluene, dymethylsulfide characterized milk from EXT farms. Also mozzarella was discriminated by VOC, but only a few compounds derived from milk. Based on sensory evaluation, milk from the two sources can be distinguished by odour and colour, mozzarella only by colour. It was hypothesized that heating during the stretching phase caused volatilization of many milk volatile compounds and formation new aroma active molecules that overcame the “primary odours” of milk.