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Purdue, USDA Use Nanoparticles To Fight Food Pathogens

by Editor1 last modified December 08, 2010 - 13:20

A Purdue University research team, supported by the U.S. Department of Agriculture, is using nanoparticles to extend the shelf life of a variety of foods by improving the effectiveness and delivery of a powerful anti-microbial.

Purdue, USDA Use Nanoparticles To Fight Food Pathogens

Nanoparticles are proving effective in extending efficacy of nisin to combat Listeria in meats, dairy and vegetables

Yuan Yao, an assistant professor of food science at Purdue, work led to the creation of several forms of a nanoparticle that can attract, stabilize and preserve nisin, a food-based antimicrobial peptide that combats foodborne pathogens.

Yao’s nanoparticles are proven in the lab to extend nisin’s effectiveness up to three weeks for combating Listeria monocytogenes, a pathogen that can be infect meats, dairy and vegetables that can be particularly dangerous to those with weakened immune systems.

"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, Yao’s co-researcher and also a food science professor at Purdue. "This nanoparticle is an improved way to deliver the antimicrobial properties of nisin for extended use."

Controlling Listeria at deli counters is especially problematic because meat is continually being opened, cut and stored, which gives Listeria many chances to contaminate the food. To date, nisin has been effective at inhibiting Listeria only for a few days. The work at Pursue looks to extend that protection by 6-7 times longer.

Inside the Purdue Team's Two Strategies for
Using Nanoparticles to Combat Foodborne Illness
Yao’s work used two strategies to attract nisin to the phytoglycogen nanopoarticles. "Both strategies may work together to allow nanoparticles to attract and stabilize nisin," Yao said, "This could substantially reduce the depletion of nisin in various systems."

First, he negatively charged the surface of the nanoparticle and used electrostatic activity to attract the positively charged nisin molecules.

Second, he created a partially hydrophobic (water-repellant) condition for the nanoparticle and nisin molecules, causing them to attract one another and interact.

For practical use, Yao said a solution containing the nanoparticles and free nisin could be sprayed onto foods or included in packaging. The solution requires a balance of free nisin and nisin on the nanoparticles, he explained. Using a model, Yao said a sufficient amount of nisin to combat Listeria could be preserved for up to 21 days.

"When you reduce the amount of free nisin, it will trigger a release of more nisin from the nanoparticles to re-establish the equilibrium," Yao said. "There will be a substantial amount of nisin preserved to counteract the Listeria."

Yao and his colleagues are working on using other food-based antimicrobial peptides and nano-constructs to combat Listeria other foodborne pathogens such as E. coli O157:H7 and salmonella. The U.S. Department of Agriculture and the National Science Foundation funded their research

The work is published in Journal of Controlled Release as “Designing Carbohydrate Nanoparticles for Prolonged Efficacy of Antimicrobial Peptide,” co-authored by Yao and Bhunia.

The paper describes how carbohydrate nanoparticles were created to prolong the efficacy of antimicrobial peptide against pathogens. Nisin and Listeria monocytogenes were used as the peptide and pathogen models, respectively, and phytoglycogen-based nanoparticles were developed as carriers of nisin.

In the experiment, phytoglycogen from su1 mutant maize was subjected to amylolysis as well as subsequent succinate or octenyl succinate substitutions. The goal was to minimize the loss of peptide during storage and meanwhile realize an effective release in the presence of bacteria.