Purpose: This study compared the effects of antimicrobial washing, surface coating, and their combination on reduction and inhibition of artificially inoculated pathogens and natural microflora on strawberries and their impacts on the quality of treated strawberries stored at 4°C.
Methods: Strawberries were inoculated with Escherichia coli O157: H7 and Salmonella spp., washed in an antimicrobial solution (90 ppm peracetic acid for 1 min), coated with a solution (1% chitason+1% allyl isothiocyanate (AIT)+1% acids), or treated in their combination (washing+coating). Treated samples were placed in PET boxes (8 oz) and stored at 4°C for three weeks. The survival and growth of inoculated pathogens and natural microflora were determined. The appearance, weight loss, color, and firmness of the strawberry were also evaluated during storage.
Results: Antimicrobial washing or coating achieved an average reduction of 0.5 to 3.0 log CFU/strawberry of E. coli O 157:H7 and Salmonella spp., natural bacteria, and yeast and mold; and also significantly (P<0.05) inhibited their growth over a three week period. The combined treatment had an additive antimicrobial effectiveness. After three weeks, the combined treatment reduced E. coli O157:H7 and Salmonellaspp. from 6.6 to 2.5, natural bacteria from 3.8 to 1.2, and yeast and mold from 4.9 to 1.1 log CFU/strawberry. In addition, the combined treatment prevented weight loss and maintained the firmness, color, and fresh appreance of strawberries during storage as compared to other strawberry samples.
Significance: The results indicated that this is a viable antimicrobial method to improve the microbiology safety and quality of strawberries from field to table.