Application of Polylactic Acid Coating with Antimicrobials in Reduction of Escherichia coli O157:H7 and Salmonella Stanley on Apples


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Abstract:  Survival of Escherichia coli O157:H7 and Salmonella Stanley on apples as affected by application of polylactic acid (PLA) coating with antimicrobials was investigated. Golden Delicious apples were spot inoculated with E. coli O157:H7 or S. Stanley and spray coated with PLA solutions containing lactic acid (LA), disodium ethylenediaminetetraacetic acid (EDTA), sodium benzoate (SB), potassium sorbate (PS), or their combination (LA + EDTA, SB + LA, SB + LA + EDTA). Apples without any coating treatment served as controls. Coating treatments were allowed to dry fully, and the apples were stored at 4 °C for 14 d. Antimicrobial coatings reduced populations of E. coli O157:H7 and S. Stanley by up to 4 log CFU/cm2 at 1 d and 4.7 log CFU/cm2 at 14 d, compared to controls. SB + LA combination had a similar effectiveness as the SB + LA + EDTA combination against both pathogens and was more effective than other coating treatments. Without antimicrobial treatment, E. coli O157:H7 and S. Stanley were able to survive on apples stored at 4 °C for up to 14 d. The antimicrobial PLA coating provides an alternative intervention to reduce the pathogens on apples.

Practical Application:  Antimicrobial PLA coatings provide an alternative method to reduce pathogenic contaminations on fruit surface, and therefore, reduce the risk of food-borne outbreaks.