Volatile organic compounds associated with milk spoilage by psychrotrophic bacteria

The volatile organic compounds of milk contaminated with psychrotrophic bacteria were studied by HS ‐ SPME and GC / MS . Pseudomonas fluorescens PS 14, Pseudomonas fragi PS 55, Pseudomonas mosselii PS 39, Pseudomonas rhodesiae PS 62 and Serratia marcescens S92 were inoculated in sterilised milk (2.5% fat) stored at either 5 °C or 10 °C. A total of 47 volatile organic compounds ( VOC s) belonging to seven chemical groups were identified in the spoiled milk. Volatile organic compound patterns peculiar to the inoculate bacterial strains were highlighted. 3‐Methylbutan‐1‐ol, 2 methylpropan‐1‐ol, 3‐hydroxybutan‐2‐one, butan‐2,3‐dione, butanoic and hexanoic acids were revealed as potential chemical spoilage indexes of milk spoilage due to the activity of the five psychrotrophic strains studied.