Manufacture of a Potential Antifungal Ingredient Using Lactic Acid Bacteria from Dry-Cured Sausages

Abstract

The growing interest in functional foods has fueled the hunt for novel lactic acid bacteria (LAB) found in natural sources such as fermented foods. Thus, the aims of this study were to isolate, identify, characterize, and quantify LAB's antifungal activity and formulate an ingredient for meat product applications. The overlay method performed a logical initial screening by assessing isolated bacteria's antifungal activity in vitro. Next, the antifungal activity of the fermented bacteria-free supernatants (BFS) was evaluated by agar diffusion assay against six toxigenic fungi. Subsequently, the antifungal activity of the most antifungal BFS was quantified using the microdilution method in 96-well microplates. The meat broth that showed higher antifungal activity was selected to elaborate on an ingredient to be applied to meat products. Finally, antifungal compounds such as organic acids, phenolic acids, and volatile organic compounds were identified in the chosen-fermented meat broth. The most promising biological candidates belonged to the Lactiplantibacillus plantarum and Pediococcus pentosaceus. P. pentosaceus C15 distinguished from other bacteria by the production of antifungal compounds such as nonanoic acid and phenyl ethyl alcohol, as well as the higher production of lactic and acetic acid.

Keywords: Lactiplantibacillus plantarum; Pediococcus pentosaceus; antifungal activity; organic acids; phenolic acids; volatile organic compounds.

Figure 1

Screening of lactic acid bacteria (LAB) through overlay method. Strong inhibitory action (a); slightly inhibitory effect (b); no inhibitory action (c); control (d).

Figure 2

The concentration of organic acids produced by LAB in meat broth (MB10) and MRS broth (MRSb) after incubation for 48 h at 37 °C. The meat broth was prepared with 10% freeze-dried loin pork and fermented by P. pentosaceus C12, P. pentosaceus C15, and L. plantarum C60. Different letters represent statistical differences in the same group of molecules between treatments (p ≤ 0.05).

Figure 3

Total percentage area (%) of the chemical classes identified in the volatile fraction of the Meat Broth formulated with 10% of lyophilized pork loin and fermented by P. pentosaceus C12 (MB12), P. pentosaceus C15 (MB15), and L. plantarum C60 (MB60). Different letters represent statistical differences in the same group of molecules between treatments (p ≤ 0.05).

Figure 4

Principal component analysis (PCA) scores plot of the bioactive compounds (organic acids, phenolic acids, and volatile organic compounds) found in the meat broth fermented by P. pentosaceus C12 (MB C12), P. pentosaceus C15 (MB C15), and L. plantarum C60 (MB C60) (a) and relative loadings of the variables employed (b).