Food Safety and Post Harvest Research

Keep Summer Produce Healthy and Safe

June 01, 2014

Published in Cabarrus Magazine June 2014.

Read the PDF: Williams Cab Mag June 2014

A recent study published in the journal Brain Research, found that the phytochemicals anthocyanins and proanthocyanidins are effective in protecting against the loss of nerve cell function in the brain brought on by Parkinson’s Disease.

One of the lead scientists on the study was Mary Ann Lila, PhD, director of the NC State University Plants for Human Health Institute at the NC Research Campus (NCRC). While Lila concentrates on finding the phytochemicals inside fruits and vegetables that keep people healthy, Leonard Williams, PhD, director of the NC A&T Center for Excellence in Post-Harvest Technologies also at the NCRC, is concerned about the pathogens on the outside of produce that make people sick.

Williams is an expert in food safety, specializing in the study of fooborne pathogens like norovirus, Listeria, salmonella, E. coli and Staphylococcus Aureus.  These pathogens cause thousands of illnesses a year and cost millions of dollars in lost productivity. To reduce the chances of these pathogens making you or your family sick, Williams suggests three easy steps:

  1. Wash

Williams urges people to wash their produce thoroughly in warm water scrubbing the folds of produce lettuce and crevices of melons meticulously. Remember that pathogens on the outside of produce, when cut end up on the inside.


  1. Separate

Eggs, meats and poultry, Williams reminds, need their own space in the shopping cart, grocery bags,  refrigerator and during meal preparation.


  1. Cool and Cook

Refrigerate food promptly, and thaw or marinate food in the refrigerator. Most pathogens grow to dangerous levels within two or less hours at room temperature. Cooler temperatures slow their growth. Heat food, when cooking or keeping it warm, to at least 140 degrees F.


Future of Food Safety

Williams is at the helm of research that has the potential to change the future of food safety. As part of a United States Department of Agriculture grant, he is developing biomaterials with antimicrobial properties. Imagine packaging produce so that dangerous pathogens are eliminated before you bring them home or having countertops manufactured with pathogen-eliminating compounds.

To achieve this, Williams is specifically looking for compounds in plants that have antimicrobial properties. For example, he published in the Journal of Medicinal Food with co-investigators from Alabama A&M University that the perennial herb plant sorrel (Hibiscus sabdariffa), has antimicrobial activity that can inhibit E. coli O157:H7.

“Bacteria have the ability to acquire resistance and mutate consistently. With natural extracts, they have not quite figured out how to change their genetic material to become resistant,” Williams said.

Williams is leading a study to track, test and isolate Verotoxin-producing E. coli (VTEC), Salmonella, Listeria monocytogenes and Staphylococcus aureus on lettuce, green onions, sprouts and spinach in North Carolina, California, the US Midwest and Mexico.

“These products have been implicated in the most recalls,” Williams said. “They are the riskiest at this point. Because we consume fruits and vegetables raw or minimally cooked, we focus on the risky products to bring the most benefit to the consumer.”

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