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Abstract
This project surveyed the hygiene status of fresh peach packing lines and determined the microbial load on peach packers’ gloves, on fresh peaches collected at the dumping vs. the weighing area, as well as before and after they pass the washing and waxing system (WWS), and in overhead spray water and spent peach wash water. The collected samples were analyzed for the levels of three hygiene indicators (total aerobes, total yeasts and molds, and total coliforms) and the incidence of two pathogen indicators (thermotolerant coliforms and enterococci). The project also assessed the distribution of 7 virulence, and 14 putative adhesins, genes among selected generic E. coli isolated from fresh peach packing environments using PCR. The results showed that counts of the hygiene indicators and incidence of the pathogen indicators on fresh peach packing lines increased overtime over the course of a packing day. Sites with higher microbial load included optical sizers, brushes/rollers inside the washer, harvest bins, and manual sorting area. The hygiene indicator populations in peach samples from the weighing area were higher than those from the dumping area. The counts of hygiene indicator microorganisms on gloves from employees working at the sorting, and the packing, area were similar. The incidences of thermotolerant coliforms and enterococci in the two areas were 39.39% and 7.58%. Levels of total aerobes and total coliforms in peach samples collected after the WWS were higher than those collected before the WWS, but an opposite trend was noticed with the total yeast and mold counts. No pathogen indicators or total coliforms were detected in the overhead spray water. The selected virulence genes were not detected, but putative adhesin genes, sfmA, ycbQ, csgA, and fimA, were found in all E. coli isolates included in the study. The number of adhesin genes varied among tested isolates. This study revealed the ineffectiveness of the packing process and WWS in improving the microbial safety of fresh peaches; suggesting that effective daily post-operation sanitation, good employee hygiene, and handling practice, and functional water safety monitoring program are important to produce safe and wholesome peaches for the fresh market.