96-2 |
Improved anti-microbial wash treatments for decontamination of apples |
G. M. SAPERS, R. L. Miller, B. A. Annous, and A. M. Mattrazzo. USDA-ARS-Eastern Regional Research Ctr., 600 E.Mermaid Ln, Wyndmoor, PA 19038
The efficacy of hydrogen peroxide washes in reducing microbial populations on contaminated apples is limited to 2-3 log10CFU/g due to microbial internalization or attachment to inaccessible surface sites such as stem and calyx areas. Improvements in treatment efficacy are needed to assure elimination of contaminating human pathogens. Our objective was to develop better means of exposing bacteria in inaccessible sites to an anti-microbial wash so that greater population reductions could be achieved. Golden Delicious apples were artificially inoculated with E. coli (ATCC 25922), held overnight at 4°C, and washed with 5% H2O2 by immersion at 50 or 60°C, with or without agitation; by targeted spraying of stem and calyx areas at ambient temperature with simultaneous brushing or reaming of these areas; or by immersion at 45°C without agitation under 100 mm Hg vacuum. Bacteria in treated samples and inoculated controls were enumerated on Petrifilm E. coli Count Plate and TSA agar. Population reductions (log10CFU/g) were greater when apples were immersed in 5% H2O2 at 60°C with agitation (2.8) than without agitation (1.8). Targeted spraying with simultaneous brushing provided no advantage over immersion with agitation. However, targeted spraying and simultaneous reaming of the stem and calyx areas yielded log reductions of 5.3. Vacuum infiltration of 5% H2O2 at 45°C, applied in conjunction with stem removal, achieved reductions of 3.9 logs, compared to 3.1 obtained without stem removal. In contrast, vacuum infiltration of 200 ppm Cl2 yielded log reductions of 2.2 with stem removal and 1.5 without stem removal. These results demonstrate the potential value of simultaneously washing with 5% H2O2 and reaming the calyx and stem areas, and of de-stemming, both of which might be applicable to apples for cider production, and of vacuum infiltrating 5% H2O2 at 45°C into apples, which might be applicable to fresh and fresh-cut packing operations.
Session 96, Fruit & Vegetable Products
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