PLA coating cuts foodborne pathogens on apples

The study by Tony Jin and Brendan A. Niemira said applying the coating to Golden Delicious apples inoculated with E.coli and Salmonella “significantly reduces”​ pathogens on the surface of the fruit.

The scientists said the application of effective antimicrobial methods was necessary “​because of the numerous food-borne outbreaks associated with contaminated fruits and the pathogens most likely originate from the contaminated surface of whole fruits”.

The study was published in the Journal of Food Science.

Method​

In the research, 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 a combination of them all.

The coating were allowed to dry fully, and the apples were stored at 4 °C for 14 days. Antimicrobial coatings reduced populations of E. coli O157:H7 and S.Stanley by up to 4 log CFU/cm² at one day and 4.7 log CFU/cm2 at 14 days, compared to controls of uncoated fruit.

The SB + LA combination had a similar effectiveness as the SB + LA + EDTA combination against both pathogens and was more effective than other coating treatments.

Significant reduction​

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“The antimicrobial ​PLA​ coating significantly reduced the pathogens on the apple surface,”​ said the research. “In general, the combined treatment of SB + LA or SB + LA + EDTA ​ was more effective againstE. coli​ O157:H7 and​ ​S. Stanley​ than other coating treatments.”​

Due the high number of foodborne outbreaks connected to contaminate fruit, the antimicrobial PLA coatings provide an alternative intervention for decontamination of apples. The same technique could also be applied for other fruits, said the scientist.

Application of Polylactic Acid Coating with ​​ Antimicrobials in Reduction of Escherichia coli O157:H7and Salmonella ​​Stanley​​ on Apples​​ by Tony Jin, Brendan A. Niemira published in the Journal of Food Science DOI: 10.1111/j.1750-3841.2011.02052.x​​