Effects of Nettle (Urtica dioica) Extract on Versus Pathogenic Microorganisms in Yogurt Production; [Yoğurt Üretiminde Isırgan Otu (Urtica dioica) Ekstraktının Patojenik Mikroorganizmalara Karşı Etkileri]

Contamination with pathogenic bacteria is the most common cause of foodborne illness and represents a public health problem worldwide. These pathogens can be controlled by adding extracts to fermented milk. In the present study, the effects of nettle extract on selected pathogenic bacteria in yogurt production were investigated. For this purpose, the antibacterial effectiveness of the extract additives in the presence of bacteria was examined and compared. Yoghurt samples, 24 different samples contaminated with 7 standard pathogen strains, were analyzed for chemical properties (pH and acidity) and antimicrobial activity after 1, 7, 14 and 21 days of storage at 4 °C. In particular, it was found that the decrease in pH and increase in acidity in the nettle extract samples after 21 days were significantly greater than in natural yogurt and yogurt samples containing nettle extract (0.5% and 1%, respectively) (p<0.05). Pathogens were reduced more significantly in samples treated with nettle extracts, which have antibacterial activity against pathogens. In particular, compared to natural yogurt, these samples showed significant antibacterial effects on the standard strains Streptococcus pneumoniae ATCC 45615, Klebsiella pneumoniae ATCC 70063 and Pseudomonas aeruginosa ATCC 27853 (p<0.01). Furthermore, in the samples containing nettle extract, the 1% concentration had synergistic effects on Streptococcus pneumoniae ATCC 45615, while the 0.5% concentration had synergistic effects on Klebsiella pneumoniae ATCC 70063 and Pseudomonas aeruginosa ATCC 27853. Overall, these results suggest that the nettle extract could be used as a natural preservative to improve the safety of yogurt and other dairy products. © Bu çalışma Tekirdağ Namık Kemal Üniversitesi tarafından Creative Commons Lisansı.