Enhancement of Probiotic Yogurts’ Characteristics using a 24-hour fermentation process

Probiotic yogurts are dairy products that contain beneficial live microorganisms that remain in sufficiently high numbers after being exposed to stomach acidity. Baladna, Al Maha and Rawa are local yogurts that have been commercialized in Qatar after the economic blockade was imposed on it in 2017, and their labelling does not indicate the species they include nor their CFU count per ml. This study is not only the first that attempts to characterize these yogurts as compared to imported probiotic yogurts (Yeo and Activia), but also tests a protocol aimed at enhancing some of their characteristics, including resistance to acidity, probiotic content, antibiotic property against pathogens and antibiotic resistance. The commercial yogurts available locally were incubated with local cow milk for 24 hours at 37 °C. Baladna and Rawa, showed significantly better resistance to acidity than Activia and/or Yeo probiotic yogurts and contain enough probiotic bacteria to be considered as probiotics. The yogurt BB37/24, which used Baladna as starter, showed the best results overall with the highest resistance to acidity than all yogurts including Activia, the highest abundance of Streptococcus thermophilus of all yogurts, the highest antibiotic property against Pseudomonas aeruginosa among lab synthetized yogurts, and the least resistance to streptomycin, chloramphenicol and tetracyclin. This study supports the benefits of using a longer fermentation during the production of probiotic yogurts.