Viability of Bacterial and Fungal Pathogens in Soft Cheese Incorporated with Some Essential Oils-Chitosan Nanoparticles

Our current study used clove and rosemary essential oils (EOs) and related EOs-chitosan nanoparticles at various concentrations to determine their inhibitory effect on the viability of bacterial and fungal pathogens (Staphylococcus aureus and Pseudomonas fluorescence), (Aspergillus flavus and Geotrichum candidum), respectively. Soft cheese was produced as control groups, fortified crude EOs cheese groups (0.1%) and EOs-chitosan nanoparticles groups (0.04%) and examined during refrigeration. EOs-chitosan nanoparticles showed more potent inhibitory effects than crude ones. Rosemary-chitosan nanoparticles reduced Staphylococcus aureus growth by 62.57%, while clove-chitosan nanoparticles reduced it by 57.97% after 48 hours of storage. At the end of 1st week of storage, rosemary-chitosan nanoparticles reduced Pseudomonas fluorescence growth by 67.43% while clove-chitosan nanoparticles (61.40%). Staphylococcus aureus was completely inhibited in all inoculated cheese samples at the end of 1st week of storage. In contrast, Pseudomonas fluorescence was totally inhibited at the end of the 2nd week of storing rosemary-chitosan nanoparticles and clove-chitosan nanoparticles. For their antifungal effect, clove-chitosan nanoparticles had potent antifungal activity followed by rosemary-chitosan nanoparticles, clove then rosemary EO. Clove-chitosan nanoparticles inhibited Aspergillus flavus and Geotrichum candidum by 90.10 and 87.47% respectively after 48hrs of storage. At the end of 1st week of storage, both fungi were completely inhibited in cheese samples fortified with clove-chitosan nanoparticles, clove EO, while rosemary-chitosan NPs made 100% reduction at end of 1st and 2nd week of storage for Aspergillus flavus and Gortrichum candidum, respectively. In conclusion, the combined clove or rosemary with chitosan nanoparticles is recommended for soft cheese preservation over crude EOs.