Identification of cheese-associated fungi using selected ion monitoring of volatile terpenes

The cheese-associated fungi Penicillium commune, P. roqueforti, P. solitum, P. discolor and Aspergillus versicolor have been investigated for production of volatile terpenes for chemical identification, when grown on yeast extract agar. Volatiles were collected by headspace solid-phase microextraction. Selected ion monitoring of four to seven of the most characteristic ions of mainly sesquiterpenes made it possible to identify the fungi to species level within 2 d. In a mixed culture of P. roqueforti and P. commune, inoculated in a ratio of 1000:1, volatiles from both fungi could be detected within 3 d, making identification possible.