Oregano essential oil-pectin edible films as anti-quorum sensing and food antimicrobial agents

Abstract

Edible films can be used as carriers for antimicrobial compounds to assure food safety andquality; in addition, pathogenesis of food bacteria is related to a cell to cell communicationmechanism calledquorum sensing(QS). Oregano essential oil (OEO) has proved to beuseful as food antimicrobial; however, its foodapplications can be compromised by thevolatile character of its active constituents.Therefore, formulation of edible films containingOEO can be an alternative to improve its food usages. QS inhibitory activity of OEO andpectin-OEO films was evaluated usingChromobacterium violaceumas bacterial model.Additionally, antibacterial activity was tested againstEscherichia coliO157:H7,SalmonellaCholeraesuis,Staphylococcus aureus,andListeria monocytogenes. OEO was effective toinhibit bacterial growth at MIC of 0.24 mg/mL for all tested bacteria and MBC of 0.24,0.24, 0.48, and 0.24 mg/mL againstE. coliO157:H7,S.Choleraesuis,S. aureus, andL.monocytogenes, respectively. Pectin-films incorporated with 36.1 and 25.9 mg/mL of OEOshowed inhibition diameters of 16.3 and 15.2 mm forE. coliO157:H7; 18.1 and 24.2 mm forS.Choleraesuis; 20.8 and 20.3 mm forS. aureus; 21.3 and 19.3 mm forL. monocytogenes,respectively. Pectin-OEO film (15.7 mg/mL) was effective againstE. coliO157:H7 (9.3 mm),S. aureus(9.7 mm), andL. monocytogenes(9.2 mm), but not forS.Choleraesuis. Allconcentrations of OEO (0.0156, 0.0312, 0.0625 and 0.125 mg/mL) and pectin-OEO films(15.7, 25.9 and 36.1 mg/mL) showed a significant anti-QS activity expressed as inhibition ofviolacein production byC. violaceum. Additionally, the application of pectin-OEO films waseffective reducing total coliforms, yeast, and molds of shrimp and cucumber slices storedat 4◦C during 15 d.These results demonstrated the potential of pectin films enriched withOEO as food related microorganisms and QS inhibitors