Tuesday, January 28, 2014

Got Salad?

Lettuce take a look at a day in the life of food safety research via a YouTube video I’m almost 100% certain you wouldn’t actively choose to watch on your own, but I’m glad science provides an excuse to do so (oh and please read comment 2 below the video at the end of the show): http://www.youtube.com/watch?v=8mSKdjxauTw.

Scientific study conducted using the pilot-scale leafy greens processing line in the video is for real. We received lettuce wash samples from this prototype production line to test a novel way for the Concentration and Detection of E. coli 0157:H7, Listeria monocytogenes, and Salmonella enterica Typhimurium in High Organic Load Lettuce Wash, using a Portable Multi-Use Automated Concentration System (PMACS, University of South Florida Advanced Biosensors Laboratory) and semi-automation and detection of TECRA VIA assays from 3M™ using the BioTek ELx50™ Microplate Strip Washer and ELx800™ Microplate Absorbance reader.

Sanitation procedures are a vital part of the food safety chain. In our experiment on the pilot-scale lettuce wash (representative results shown below) we compared concentrated (LWR, purple) to non-concentrated (LW, green) samples to observe the effects of different levels of chlorine (Cl) on reducing E. coli 0157:H7 inoculated into lettuce heads and their wash water. At 10 ppm Cl the LWR samples needed no enrichment time before the E. coli could be detected (above the red line), whereas the non-concentrated samples required greater than 0 and less than 5 hours of enrichment time (x-axis) before detection was achieved, and then still at much lower levels. The fact that both lines go up, and E. coli levels increase over time, show that viable cells that can still grow remain in the sample. In the LWR samples, this can be determined before the LW samples even show a positive result. For perishable foods like produce, the ability to go straight from bacterial screening to confirmation of samples could potentially make this method beneficial to food processors looking for a low-cost way to save testing time while still ensuring food safety of product. Got Salad?


By: BioTek Instruments,Wendy Goodrich, Applications Scientist

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