Factors limiting the efficacy of hydrogen peroxide washes for decontamination of apples containing Escherichia coli

Factors limiting efficacy of H2O2 washes and alternative decontamination st rategies were investigated with Golden Delicious apples, inoculated with no npathogenic Escherichia coli. Post-treatment rinsing decreased efficacy by eliminating residual H2O2. A 2-stage wash incorporating a rinse to remove s urfactant residues prior to H2O2 application was developed. Rapid attachmen t of E. coli to apples prevented effective removal by washing with water. S urviving E. coli following a 5% H2O2 wash were concentrated in stem and cal yx areas. Survival was independent of the time interval between inoculation and washing. E. coli inoculation of punctured apple surfaces resulted in g rowth at 20 degrees C and greater survival after washing with 5% H2O2. Impr oved decontamination methods are needed.