The ability of Lactobacillus plantarum to produce exopolysaccharides (EPS) of various structures and properties is effective in showing both starter and probiotic culture qualification. In this study, the potential health promoting functions of the ropy EPS produced by Lactobacillus plantarum strains isolated from tarhana were tested. A stimulation of the pro-inflammatory IL-12 and TNF-α cytokines was observed in the presence of the ropy EPS suggesting an in vitro immune modulation. Similarly, the tested EPS demonstrated promoted the growth of the probiotic strains in fermentation medium. A medium level of radical scavenging activities of ropy EPS was observed whereas the superoxide and hydroxyl scavenging activities were more effective. The ropy EPS also showed α-glucosidase inhibition and cholesterol removal characteristics depending on their concentration. These findings revealed the potential health-promoting functions of ropy EPS from L. plantarum strains and EPS from L. plantarum PFC311 and PFC310 strains demonstrated multiple health-improving effects that can be further evaluated in food and other industries.

Tarhana is a traditional cereal product fermented by lactic acid bacteria (LAB) and yeast strains that has gained special interest recently as an infant nutrition. Tarhana contains wheat flour, yogurt, and various vegetables that might create a microbiological toxicological risk, especially for Bacillus cereus and Staphylococcus aureus. In this study, characterization of the metabolites responsible for antibacterial activity of Pediococcus acidilactici PFC69 and Lactococcus lactis PFC77 strains obtained from tarhana was performed, and antibacterial effects were detected against B. cereus ATCC 11778 and S. aureus ATCC 29213 during the fermentation. A total of 12,800 AU/mL antibacterial activity was observed for the supernatants of the PFC69 and PFC77 strains that were found to be stable at high temperature and in low pH conditions and sensitive to proteases, suggesting the antimicrobial metabolite is a bacteriocin. These bacteriocins were further purified and their molecular sizes were determined as 4.5 and 3.5 kDa, respectively. Importantly, inoculation of PFC69 and PFC77 to tarhana dough significantly decreased B. cereus ATCC 11778 and S. aureus ATCC 29213 amounts from the fifth day of fermentation compared to the control dough samples. P. acidilactici PFC69 and L. lactis PFC77 strains were concluded as bioprotective cultures for tarhana and these strains were offered for other cereal-based fermentations.