Effect of some Herbs Essential Oils on Labneh

Abstract

Labneh is one of the most popular dairy products in many Middle Eastern countries. The shelf life of labneh is short even if stored at low temperature. Therefore, chemical preservatives were used to control the activity of contaminant microorganisms. An increased awareness of the harmful chemical residues in food led to a restricted use of chemical preservatives. Recently, natural substances such as spices oil can be used to prolong the shelf life of food products, because they are antioxidant and antimicrobial agents. In the present study three essential oils namely rosemary (Rosmarinus officinalis), sage (Salvia officinalis) and cumin (Cuminum cyminum) were characterized by means of GC-MS and their antioxidant capacity were studied. Also, their antibacterial activity against pathogens E. coli, B. cereus and S. aureus was determined in vitro by wells' agar diffusion method. The results obtained revealed that the tested essential oils exhibited noticeable antimicrobial activity, where cumin showing the highest inhibition and sage the lowest. The results were completed with the study the antibacterial effect of the tested essential oils in vivo (labneh). However, the previous results obtained by in vitro assays were confirmed by in vivo experiment. In addition, three batches of labneh supplemented with different essential oils were made. No noticeable differences were observed in physicochemical properties of labneh treatments in comparison with the control one. However, labneh made with 0.05% rosemary essential oil ranked the highest value of antioxidant activity after 14 days of storage, being 20.78, while plain labneh (control) possessed the lowest figure, actually 10.8. Moreover, at the end of storage period, labneh produced with 250 mg/Kg cumin essential oil was the most preferred product by the panelists and ranked the highest total score, being 87 points.