Survival and growth of transferred salmonella and aerobic mesophilic bacteria from melon rinds to fresh juices during juices preparation

Authors: Ukuku, Dike; Mukhopadhyay, Sudarsan; Olanya, Modesto

Submitted to: Frontiers in Sustainable Food Systems
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/22/2018
Publication Date: 12/7/2018
Citation: Ukuku, D.O., Mukhopadhyay, S., Olanya, O.M. 2018. Survival and growth of transferred salmonella and aerobic mesophilic bacteria from melon rinds to fresh juices during juices preparation. Frontiers in Sustainable Food Systems. https://doi.org/10.3389/fsufs.2018.00078.
DOI: https://doi.org/10.3389/fsufs.2018.00078

Interpretive Summary: Consumers’ demand for fresh, healthy, nutritious foods has caused food industries to look for quicker and easier way of producing higher quality juices. Cantaloupe, watermelon and honeydew melon juices were prepared from melons washed with 200 ppm chlorine. Some of the juices were held at room temperature for several hours before refrigeration. Holding the juices at room temperature for 5 h led to higher microbial populations and increased the total soluble solids and pH. The results suggests that proper chlorine wash of melons before juice preparation, and immediate refrigeration of prepared juice will improve the microbial food safety by suppressing bacterial populations transferred from the melon rinds during juice preparation.

Technical Abstract: Transfer, survival and growth of Salmonella and aerobic mesophilic bacteria, yeast and mold, lactic acid bacteria and Pseudomonas from whole melon surfaces to freshly prepared fruit juice and conditions that can minimize transfer and survival of the bacteria was investigated. Cantaloupes, honeydew melons and watermelons inoculated with Salmonella cocktail at 4.5 log CFU/cm2, 3.8 log CFU/cm2 and 3.2 log CFU/cm2, respectively were sanitized with 200 ppm chlorine before rinds removal and fresh-cut pieces and juice preparation. Approximately 500 g of each melon fresh-cut pieces (~ 2 cm/piece) were placed inside stomacher bag containing 100 ml sterile deionized water. The stomacher bag was pummeled for 2 min in a stomacher model 400 at medium speed. The melon juice filtrates were refrigerated immediately while some were left at room temperature (~22C) for 5 h before refrigeration. Average Salmonella bacteria recovered in fresh melon juice prepared from whole cantaloupes, watermelon and honeydew melons washed with 200 ppm chlorine was 1.4 log CFU/ml, 0.5 log CFU/ml and 0.4 log CFU/ml, respectively. Holding these juices at room temperature for 5 h before refrigeration allowed Salmonella bacteria to increase by 0.5-0.8 log in cantaloupe juice and 0.3-0.5 log in watermelon and honeydew juices. Juices from unwashed inoculated melons had the most bacterial populations and storage at an abusive temperature of 10C led to proliferation. The results of this study showed that holding freshly prepared contaminated fresh- melon juices at 22C for 3 h or more prior to refrigeration would increase the chances of Salmonella proliferation.