Application of polylactic acid coating with antimicrobials in reduction of Escherichia coli O157:H7 and Salmonella Stanley on apples.

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