Growth and metabolites production by Penicillium brevicompactum in yoghurt

Penicillium brevicompactum, commonly encountered in the indoor air, is known to produce a mycotoxin, mycophenolic acid (MPA). This mould has been isolated from a wide range of foods; considering that we had previously isolated this species from contaminated yoghurt, in this study we have evaluated its growth in yoghurt sweetened with sucrose, fructose and fructose added with fruit pieces. Fungal growth was evaluated monitoring CO2 production in the headspace during yoghurt storage at 4 ± 1, 8 ± 1 and 10 ± 1 °C throughout 21 days. P. brevicompactum grew well in the samples sweetened with fructose at 8 and 10 °C. The addition of sucrose influenced the growth negatively, particularly at 4 °C. Volatile Organic Compounds (VOC) and MPA production was determined at 8 °C in inoculated and uninoculated yoghurt, as well as in liquid malt extract. Differences in VOC profiles and in MPA production were correlated with the age of the fungus and with the growth medium. This study points out for the first time the early qualitative changes in volatile production patterns of a common indoor mould, grown in yoghurt, as well as the production of MPA during storage at refrigeration temperatures.