Investigation of the Effect of Hop (Hyssoupus officinalis L.) and Hyssop (Humulus lupulus L.) Ethanolic Extracts on the Prevention of Staphylococcus aureus Growth in Doogh

Nowadays with regard to the harmful effects of synthetic preservatives onconsumers' health, the use of natural antimicrobial compounds such as herbal extracts in foodpreservation is considerably increasing. Doogh or drinking yogurt is a kind of dairy drinkmade of yoghurt and water which is highly favored in Iran. Staphylococcus aureus is abacterium causing toxicity in dairy products. The purpose of this study is to investigate theeffect of hop and hyssop ethanolic extracts on the prevention of Staphylococcus aureusgrowth in doogh. Minimum Inhibitory Concentration (MIC) and MinimumBactericidal Concentration (MBC) of hop and hyssop ethanolic extracts were calculated.Moreover, the antibacterial activity of those extracts was examined using diffusion diskmethod, and chemical and sensory properties of doogh were also tested on the 1st, 7th, and 14thdays. MIC of hop and hyssop extracts were respectively 12.5 mg/mL and 6.25 mg/mL,whereas MBC of those extracts were respectively 25 mg/mL and 12.5 mg/mL. By addingherbal extracts, acidity of the samples decreased and pH increased (p<0.05). Moreover, byadding herbal extracts, the scores of sensory properties of the samples decreased (p<0.05).Among the samples containing herbal extracts, sample containing 12.5 mg/mL hyssop extracthad the best sensory quality. Hop and hyssop extracts had antimicrobial activity against Staphylococcusaureus and they can be used as natural preservatives in doogh. Among doogh samples,sample containing 12.5 mg/mL hyssop extract can be selected as the best sample regarding itssuitable antimicrobial activity and sensory quality.