Black seed oil impact on authentic kefir microbiota

Introduction: Authentic kefir originates from the Caucasus mountains of Eastern Europe and is a fermented milk product made from kefir grains. Authentic kefir contains lactic acid bacteria, acetic acid bacteria and yeasts which provides kefir with numerous health benefits such as anticarcinogenic, antimutagenic and anti-allergic properties. Nigella sativa is a plant known by many regional names such as black cumin and black carraway. Seeds from the plant are processed to produce black seed oil. Black seed oil has many potential health benefits such as antibacterial and antifungal capabilities. In countries including Turkey and India, black seed oil is commonly added to kefir or yogurt. The purpose of this study was to determine if different concentrations of black seed oil would negatively impact beneficial kefir microorganisms when consumers mix black seed oil into kefir.  Results: Black seed oil concentrations of 0%, 0.1%, 1% and 5% were added to milk with kefir grains and incubated. Each mixture was tested for pH, Lactobacillus spp., Lactococcus spp., yeast, and coliform microbial counts. Results indicated that the pH and microbial counts of the control (0%) and 0.1% black seed oil samples were not significantly different (P > 0.05). The pH and microbial count results of 1% black seed oil in kefir indicated slight although not significant inhibition (P > 0.05) as compared to the control and 0.1% black seed oil. The pH and microbial counts of 5% black seed oil were significantly different (P < 0.05) from the other samples indicating inhibition of the kefir microorganisms.Conclusion:Black seed oil inhibited kefir microorganism when added at the rate of 5%.Keywords: Kefir, Black Seed Oil, Lactobacillus spp., Lactococcus spp., Yeast, Probiotic