Biocontrol Ability Against Harmful Microbial Contamination of Vegan Mortadella with an Ingredient of Oat Fermented by Lactiplantibacillus plantarum

The rising demand for vegan products calls for new plant-based antimicrobial preservation methods. This study evaluates an antifungal ingredient obtained by fermenting oat drink with lactic acid bacteria to extend vegan mortadella’s shelf life. In vitro tests showed antimicrobial effects against Aspergillus flavus, Penicillium commune, and Listeria monocytogenes (inhibition zones: 2–5 mm). The enrichment of the oat drink culture medium with additional nutrients enhanced fermentation performance and increased antifungal activity. The fermented culture medium with the highest antimicrobial activity was used to develop a bioactive ingredient for the preservation of vegan mortadella conservation. Adding 3% of this ingredient to vegan mortadella improved microbial stability, reducing mesophilic bacteria by 2.5 Log10 CFU/g and increasing lactic acid bacteria. Lower pH and water activity changes were observed but remained within quality standards. Contamination assays showed a consistent reduction of A. flavus over 7 days, while P. commune and L. monocytogenes dropped below detection within 2 days. In contrast, control samples maintained contamination levels near 3.0 Log10 CFU/g. These findings support the potential of fermented oat-based ingredients as effective, natural preservatives for vegan foods.