A limited antifungal effect of EO water and NaOCl solution on
strawberries inoculated withL. monocytogenesandE. coliO157:H7
was observed. Residual NaOCl and EO water after treatment did notgive a fungicidal effect greater than DW on inoculated fruit with
bothL. monocytogenesandE. coliO157:H7. Numbers of yeast and
mold obtained fromE. coliO157:H7 inoculated strawberries at 15 d
of storage after treatment with EO water was the only observation
indicating the reduction of yeast and mold populations after lowtemperature storage which also exhibited a greater fungicidal activity of EO water as compared with DW. Significant increases in the
yeast and mold population were observed withL. monocytogenes
contaminated berries. Growth of yeast and mold on strawberries after the sanitizing treatment and stored at refrigeration temperature
was also reported by Rodgers and others (2004).
Strawberries have an irregular shape and complicated morphological structure. They comprise 5 tissue zones, epidermis, hypodermis, cortex, bundle, and pith, and also numerous achenes (seeds)
embedded in epidermis rendering the surface uneven and complex
(Szczesniak and Smith 1969; Han and others 2004). Koseki and others (2004) reported that the incomplete elimination of naturally occurring microorganisms by EO water and 150 ppm NaOCl solution
may result from the complexity of strawberry’s surface structure. Yu
and others (2001) also pointed out that the rough surface and the
presence of numerous seeds on the strawberry surfaces may provide the attachment sites for bacteria, and may compromise the
effectiveness of sanitizers. Although the microbial load inoculated
onto samples in the current study was relatively high, there may be
cases where strawberries will be contaminated with similar numbers of pathogen. Therefore, the investigated sanitizers may be more
efficacious in reducing or eliminating disease causing bacteria on
strawberries in a real world situation