Inhibitory activity of aromatic plant extracts against dairy-related Clostridium species and their use to prevent the late blowing defect of cheese

The aim of the present work was the selection of aromatic plant essential oils (EOs) and/or ethanolic extracts (EEs) to prevent the late blowing defect (LBD) of cheese caused by Clostridium spp. EEs resulted more effective than EOs to inhibit dairy-borne Clostridium spp. in vitro. Savory, hyssop, lavender and tarragon EEs, which showed the lowest minimal inhibitory concentration against Clostridium tyrobutyricum, were selected to study the prevention of LBD caused by this bacterium in cheese. Addition of savory and lavender EEs to cheese milk delayed LBD by 2 weeks, but at the end of ripening these cheeses showed similar clostridial vegetative cells counts, spoilage symptoms and propionic, and butyric acids levels than blown control cheese. Tarragon EE, with the highest content in caffeic acid, also delayed LBD by 2 weeks, but it was more effective to inhibit Clostridium, since cheese with tarragon EE showed minor LBD symptoms, lower vegetative cells count and lower concentrations of propionic and butyric acids than the rest of cheeses made with EEs. This fact could be also attributable to the greater number of antimicrobial terpenes (1,8cineole, 4-terpineol, alpha-terpineol, isoelemicin, methyl eugenol, and methyl trans-isoeugenol) detected in this cheese. This is the first report on the application of EEs to control C. tyrobutyricum in cheese.

Automated summary

The study aimed to select aromatic plant essential oils (EOs) and/or ethanolic extracts (EEs) to prevent late blowing defect (LBD) of cheese caused by Clostridium spp. EEs were found to be more effective than EOs in inhibiting dairy-borne Clostridium spp. in vitro. Four EEs (savory, hyssop, lavender, and tarragon) with the lowest minimal inhibitory concentration against Clostridium tyrobutyricum were selected to study their prevention of LBD in cheese. Among them, savory and lavender EEs delayed LBD by 2 weeks, while tarragon EE, with the highest content of caffeic acid and antimicrobial terpenes, showed the best efficacy in inhibiting Clostridium and reducing LBD symptoms in cheese.