Browsing by Author "Kavela, Efaishe Tweuhanga Angaleni"

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    Microbial evaluation of selected produce pre- and post-pack-house and at the formal retail point-of-sale
    (Stellenbosch : Stellenbosch University, 2020-04) Kavela, Efaishe Tweuhanga Angaleni; Sigge, G. O.; Lamprecht, Corne; Stellenbosch University. Faculty of AgriSciences. Dept. of Food Science.
    ENGLISH ABSTRACT: Fresh produce consumption is important to humans as it provides important nutrients and other compounds that promote good health. However, consumption of contaminated produce can be detrimental to human health. Outbreaks linked to fresh produce consumption have been reported globally, with Enterobacteriaceae members such as Escherichia coli and Salmonella being the most frequently implicated bacteria. Fresh produce isolates carrying the extended spectrum β-lactamase (ESBL) producing Enterobacteriaceae has been reported. These organisms can resist the action of penicillin and the broad-spectrum cephalosporins, and they are also resistant to other antimicrobials. This is such a concern because fresh produce is eaten raw and these organisms are not inactivated before consumption. To be able to control the spread of contaminations and antimicrobial resistance along the fresh produce production chain, it is essential to know the microbiological quality of fresh produce at different stages of production. The aim of this study was to determine the changes in the microbiological quality of fresh produce pre- and post-pack-house processing and at the formal point-of-sale, in order to identify potential contamination points along the supply chain. Different fresh produce types: broccoli coleslaw (broccoli stems, carrots and cabbage) and lettuce samples were collected at different processing points within a pack-house situated in Phillippi, Western Cape, South Africa. Some pack-house samples (mixed coleslaw bags and lettuce pre-packs) were also collected from retail outlets. All samples were tested for microbial indicators (Enterobacteriaceae, coliforms and E. coli), Salmonella and Shiga-toxin producing E. coli (STEC). Produce samples were also screened for ESBL-producing Enterobacteriaceae. The untreated/unprocessed samples had high microbial counts which were then reduced to significantly lower levels after peeling and washing in a chlorine (150-200 ppm) solution. An increase in microbial counts to levels significantly higher than on the treated samples was observed in shredded samples and bagged mix coleslaw samples. Mixed coleslaw bags sampled from the retailer two days after packaging also had significantly higher microbial levels than mixed coleslaw from the same batch sampled at the pack-house directly after packaging. Lettuce samples have indicated a gradual decrease on microbial levels throughout, and the lowest reduction was detected on pillow-packs samples. Throughout the study, no Salmonella or STEC were detected. Fifty isolates were identified as Enterobacteriaceae with MALDI-TOF, of which 22% were confirmed as ESBL producers according to the EUCAST disk diffusion method (2017b). All 50 Enterobacteriaceae were also subjected to genotypic confirmation, and seven of them were carrying the ESBL genes: blaCTX-M and blaTEM. Enterobacter cloacae and Klebsiella oxytoca isolates were found carrying blaCTX-M and blaTEM, and a single blaTEM was found on an E. coli isolate. All 50 Enterobacteriaceae were also tested for resistance against ampicillin, gentamicin, tetracycline, ciprofloxacin, and chloramphenicol. Five of the 50 tested isolates were found to be multidrug resistant. Fresh produce is eaten raw without thermal treatment to deactivate these organisms carrying ESBL genes. Through ingesting of this produce the ESBL genes could be transferred to the intestinal microorganisms and will confer resistance to important antimicrobials. This study investigated the microbiological quality of fresh produce sold in the Western Cape and has also identified shredding and packaging as potential contamination points. Given favourable conditions, microorganisms may grow on stored fresh produce over time.