Evaluation of combinations of nisin, lauric arginate, and ε-polylysine to control Listeria monocytogenes in queso fresco

Listeria monocytogenes contamination is of great concern in queso fresco (QF), and listeriosis outbreaks linked to consumption of QF continue to happen. Hurdle approaches such as combining antimicrobials provide an alternative to improve QF safety. In this work, the efficacy of antimicrobial combinations of nisin (NIS), lauric arginate (LAE), and ε-polylysine (EPL) to inhibit L. monocytogenes growth in QF was evaluated. First, antimicrobials were screened for potential synergy in vitro. Later, antimicrobial treatments were challenged in QF inoculated with ∼4 log₁₀ cfu/g of L. monocytogenes 5-strain cocktail and stored for 28 d at 4°C. Our results showed that combinations of NIS-LAE and EPL-LAE were synergistic in vitro. Limited antilisterial control was observed in QF treated with NIS, LAE, and NIS-LAE; however, EPL and EPL-LAE exhibited listeristatic effect in QF for up to 14 and 28 d of cold storage, respectively. Additionally, L. monocytogenes QF isolates had similar susceptibility to EPL or LAE. A consumer panel was able to distinguish between QF added with EPL (250 µg/g) + LAE (66.66 µg/g) and control QF, most likely associated with manufacturing and storage rather than antimicrobials' taste. Our results support the use of EPL-LAE combination to control L. monocytogenes growth in QF.