Abstract
Background: Nowadays, microbial food safety is an increasing public health concern worldwide, especially in developing countries. Objectives: The aim of this study was to apply established in vitro tests to evaluate the antimicrobial activity of the Lactobacilli. isolated from two traditional Iranian fermented dairy-cereal based foods. Materials and Methods: A total of 23 samples of Kashk-e Zard and 27 samples of Tarkhineh were collected from different regions of Iran. Lactobacillus spp. was isolated and identified by standard methods. The antibacterial effects of Lactobacillus isolates were implemented by well diffusion method. Kinetic study was conducted with a bacteriostatic activity in vitro in the presence of Lactobacillus supernatants. Results: The results showed an antimicrobial activity of the Lactobacillus strains isolated from Kashk-e Zard and Tarkhineh against Escherichia coli, Staphylococcus aureus, Listeria monocytogenes and Salmonella typhimurium according to agar well diffusion test. In addition, kinetic study revealed a significant bacteriostatic activity of Lactobacillus supernatants. Conclusions: Kashk-e Zard and Tarkhineh seemed to have probiotic properties, deserving further studies.
Highlights
Nowadays, microbial food safety is an increasing public health concern worldwide, especially in developing countries
Based on the fermentation profile, seven and eight categories of Lactobacillus spp. were identified for Kashk-e Zard and Tarkhineh respectively, of which the most and the least frequent isolates belonged to L. casei (n = 20 and n = 28) and L. acidophilus (n = 2 and n = 1), respectively
Regarding isolates of Kashk-e Zard, the strongest growth inhibition against E. coli, S. aureus, L. monocytogenes and S. typhimurium were respectively shown by L. corustorum, L. plantarum, and L. casei
Summary
Microbial food safety is an increasing public health concern worldwide, especially in developing countries. Fermentation is one of the most practical, economic and widely applied empirical methods for preserving, often diversifying and enhancing organoleptic and nutritional quality of fresh foods [1, 2]. These foods such as Kashk-e Zard and Tarkhineh are still mainly prepared at the household level and marketed through informal routes. They have a high nutrition value and are considered as a good source of bioavailability such as protein, vitamins and minerals [3]. These fermented products are popular in the southeastern part of Iran (Sistan and Balouchestan province), produced by mixing cereal flour (mainly wheat flour), yoghurt, a variety of vegetables, salt and spices, followed by lactic and alcoholic fermentation in two steps of fermentation for several days
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