Evaluating the antimicrobial effects of postbiotics derived from Lactobacillus casei on E.coli and Listeria monocytogenes in vitro codition and yoghurt

Abstract

postbiotic, probiotic, functional food, antimicrobial effects

to determine the minimum effective postbiotic concentration in yogurt. The sensory properties of yogurt were evaluated by a 5-point hedonic test. Physicochemical properties were evaluated based on the national standard methods of yogurt - test characteristics and methods (No. 695).

Results

In the evaluation of the antimicrobial effect of the desired postbiotic, it was observed that the cell wall has no antimicrobial effect. The supernatant obtained at concentrations of 12.5 mg/ml and 25 mg/ml prevented the growth of Escherichia coli and Listeria monocytogenes, respectively. In addition, the concentration of 50 mg/ml of it had a lethal effect on these two bacteria. Addition of postbiotic to yogurts infected with Escherichia coli and Listeria monocytogenes showed that the growth of Escherichia coli stopped on the seventh day of storage. Also, the growth of Listeria monocytogenes decreased during the storage period. The sensory evaluation results of post-biotic yogurt and regular yogurt did not show a significant difference in overall acceptance (p<0.05), although regular yogurt scored higher.

conclusion

Considering the ability of the postbiotic derived from Lactobacillus casei bacteria to inhibit bacterial contamination and also the acceptability of post-biotic yogurt produced from the sensory point of view, it is possible to use the postbiotic produced from Lactobacillus casei bacteria to produce post-biotic yogurt on an industrial scale. used.

Abstract Introduction and aim

Humans are always looking for a way to preserve food from chemical, microbial, and food pathogen degradation. Recently, the use of natural and healthy additives has been noticed by producers and consumers. The use of probiotics is facing challenges today. To get out of this impasse, postbiotics can be used as a substitute for probiotics. Due to their antimicrobial properties, postbiotics can have a good position in the food industry. The aim of this study is to determine the antimicrobial effect of postbiotics obtained from Lactobacillus casei on Escherichia coli and Listeria monocytogenes in yogurt and external environment.

Materials and methods

Lactobacillus casei bacteria were cultured in MRS broth to prepare postbiotics. Lyophilized bacteria were inoculated in MRS broth for 18 hours at 37 degrees Celsius. In order to prepare the post-biotic powder, we used a centrifuge at 10000 rpm for 20 minutes at a temperature of 4 degrees Celsius. We lyophilized the resulting supernatant containing the desired postbiotic and added it to yogurt as a powder. The MIC method was used to determine the minimum postbiotic inhibition concentration against Escherichia coli and Listeria monocytogenes bacteria, the MBC test was used to determine the minimum postbiotic lethal concentration against Escherichia coli and Listeria monocytogenes bacteria, and the MEC test was also used