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Submitted to: International Journal of Food Microbiology
Publication Type: Peer Reviewed Journal Publication Acceptance Date: 1/23/2004 Publication Date: 5/1/2004 Citation: Ukuku, D.O. 2004. Effect of hydrogen peroxide treatment on microbial quality and appearance of whole and fresh-cut melons contaminated with salmonella spp. International Journal of Food Microbiology. 95:137-146. Interpretive Summary: The presence of organic matter greatly reduces the effectiveness of chlorine as a disinfectant. Hydrogen peroxide and chlorine were compared as decontaminants for Escherichia coli O157: H7 or Salmonella on melons. Honeydew and cantaloupe melons were immersed in an inoculum containing Escherichia coli O157: H7 and Salmonella (8 log CFU/ml) for 10 min and then stored at 20 C for 24 h. Inoculated melons were washed with chlorine or hydrogen peroxide and fresh cut pieces were prepared. The cut pieces were placed in stomacher bags and stored at 4, 8 and 12 C for up 15 days. Microbial safety and quality of the fresh-cut melons were evaluated every 3 days during refrigerated storage. The results of the study indicated that neither treatment was capable of completely decontaminating melons, however both treatments substantially reduced the transfer of pathogens from the interior tissue during cutting. The results indicate that chlorine or hydrogen peroxide treatments will improve the quality of fresh-cut melons. Technical Abstract: The efficacy of chlorine or hydrogen peroxide in reducing transfer of Escherichia coli O157:H7 and Salmonella from the rind of honeydew or cantaloupe melon to the fresh-cut tissue and subsequent growth of the transferred pathogens on the interior tissue was studied. Changes in quality attributes for the fresh cut pieces were also evaluated during refrigerated storage. Uninoculated or inoculated whole melons were washed with 1000 ppm free chlorine or 5% hydrogen peroxide, peeled and cut into pieces. Populations of pathogens, which survived the treatments, were enumerated. The cut pieces were placed in stomacher bags and stored at 4, 8 and 12oC for up 15 days. Populations of native mesophilic aerobes on inoculated, treated whole cantaloupe and honeydew melons averaged 6.48 and 3.53 log CFU/cm2, respectively. Hydrogen peroxide treatment was more effective than chlorine in reducing the population of native bacteria on whole cantaloupe and honeydew melon and the population transferred to minimally processed fresh-cut pieces. Both treatments were equally effective in reducing populations on rinds. For surface-sanitized melons, the inoculated bacteria determined in fresh-cut pieces were 0.38 log CFU/g for Salmonella and 0.50 log CFU/g for Escherichia coli O157:H7 and remained the same throughout storage at 4oC. Pathogen populations on fresh-cut pieces stored at 8oC or 12oC increased and by two weeks reached ~ 1 and 2 log CFU/g for Salmonella and E. coli O157:H7, respectively. A rapid decline in appearance, odor and overall acceptability for fresh-cut pieces prepared from whole melons that were not surface sanitized was observed during refrigerated storage. Sanitizing the surface of whole melons before cutting and storage of the fresh-cut pieces at 4oC can ensure a longer shelf life and higher acceptability rating for about two weeks. |
