WEST LAFAYETTE, Ind. - A Purdue University research team developed a nanoparticle that can hold and release an antimicrobial agent as needed for extending the shelf life of foods susceptible to Listeria monocytogenes.
Yuan Yao, an assistant professor of food science, altered the surface of a carbohydrate found in sweet corn called phytoglycogen, which led to the creation of several forms of a nanoparticle that could attract and stabilize nisin, a food-based antimicrobial peptide. The nanoparticle can then preserve nisin for up to three weeks, combating Listeria, a potentially lethal foodborne pathogen found in meats, dairy and vegetables that is especially troublesome for pregnant women, infants, older people and others with weakened immune systems.
Controlling Listeria at deli counters, for example, is especially problematic because meat is continually being opened, cut and stored, giving Listeria many chances to contaminate the food. Nisin alone is only effective at inhibiting Listeria for a short period - possibly only a few days - in many foods.
"People have been using nisin for a number of years, but the problem has been that it is depleted quickly in a food system," said Arun Bhunia, a Purdue professor of food science who co-authored a paper with Yao on the findings in the early online version of the Journal of Controlled Release. "This nanoparticle is an improved way to deliver the antimicrobial properties of nisin for extended use."
Yao used two strategies to attract nisin to the phytoglycogen nanopoarticles. First, he was able to negatively charge the surface of the nanoparticle and use electrostatic activity to attract the positively charged nisin molecules. Second, he created a partially hydrophobic condition on the surface of the nanoparticle, causing it to interact with partially hydrophobic nisin molecules. When the particles are hydrophobic, or repel water, they becom
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