Black cumin seed oil (BCSO) was tested for its inhibitory effect against some pathogenic bacteria (Staphylococcus aureus ATCC 6538, Escherichia coli ATCC 8739, Listeria monocytogenes Scott A and Salmonella enteritidis PT4) in Domiati cheese during cold storage. Physical, chemical and sensorial changes in cheese during storage were recorded. Pasteurized milk was inoculated before renneting with a mixed culture of bacteria at ca. 4 log CFU mL(-1). In vitro and in situ supplementation with BCSO showed antimicrobial impact on the growth of S. aureus, E. coli, L. monocytogenes and S. enteritidis inoculated into media and cheese samples. Supplementing of cheese with BCSO (0.1% or 0.2%, w/w) significantly reduced the counts of the inoculated pathogens by ca. 1.3 log and 1.5 log CFU g(-1) after 21 days of storage. In addition, BCSO controlled the development of titratable acidity, limited the changes in ripening indices, flavor components and kept considerable physicochemical and sensorial properties of cheese.

The impact of adding cold-pressed black cumin seed oil (BCSO) at levels of 0.1 and 0.2% w/w to Domiati cheese supplemented with probiotic cultures on the growth inhibition of foodborne pathogens (Staphylococcus aureus, Escherichia coli, Listeria monocytogenes and Salmonella enteritidis) inoculated in cheese during storage at 4C for 42 days was investigated. BCSO showed antimicrobial effect on the survival of St. aureus, E. coli, L. monocytogenes and Sa. enteritidis inoculated into probiotic Domiati cheese samples. BCSO at concentration of 0.2% w/w had the most effective antimicrobial activity on pathogens when compared to the control. L. monocytogenes and Sa. enteritidis were more resistant against BCSO up to 28 days, whereas E. coli and St. aureus were more resistant up to 14 days of storage. Storage life of BCSO-supplemented chesses was extended under refrigerated conditions with low microbial loads. BCSO-supplemented Domiati chesses had also improved physicochemical and sensory properties. PRACTICAL APPLICATIONConsumers are in quest of natural preservatives for healthier lifestyles and natural ways of preventing ailments. Spices are being sought for their medicinal value as antioxidants and as antimicrobials. White soft cheese is one of the most appreciated soft cheeses worldwide. In the current work, BCSO was applied as antibacterial and antioxidant agent during manufacture and storage of Domiati cheese prepared with starter cultures containing contaminating bacteria as well as artificially inoculated bacterial pathogens. It can be stated that BCSO have general antibacterial against pathogenic bacteria. BCSO also enhance the physicochemical and sensory attributes of cheese. This endowed potentiality can participate in keeping a good hygienic quality of soft cheese during storage under cold conditions. The results from the present study could be used to develop novel soft cheese rich in bioactive molecules with a desirable shelf life.

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