Pecan Shells Could Protect Against Food Bacteria

Developing a way to protect pecans and to keep them safe for consumption is the goal of an LSU student who just returned from Poland.

Karuna Kharel, a doctoral student in the School of Nutrition and Food Science, spent one month this summer at the Warsaw University of Life Sciences to study the antimicrobial and antibacterial activity of pullulan film with extracts from pecan shells.

Kharel, a native of Nepal, has been looking for uses for the waste material. She was able to combine her efforts with a group at the university in Poland that was working with pullulan film, which is a water-soluble polysaccharide produced by fungi that have antimicrobial and antibacterial properties.

“The work that I did there will be part of my dissertation, and I will complete the work back here,” she said.

There is no significant pecan production in Poland, but the work being done there was complementary of the work she’s doing.

“I collected pecans from different orchards in Louisiana, ground them to powder, removed the fat and then extracted the bioactive compounds,” she said. “The extraction was done either using water or ethanol to see what the difference would be in its antimicrobial property,”

The next step in the process is to apply the film to food matrixes such as egg shells or food packaging.

“The film with extract reduces the zone of bacterial growth, but what we want to know is, does it actually kill the bacteria or just inhibit the growth?” she said.

AgCenter food safety specialist Achyut Adhikari said the extract has shown promise in eliminating salmonella, listeria and E. coli bacteria.

“One of the things we would like to do with this extract is to use it in food packaging, such as for strawberries,” he said.

Sixteen varieties of pecans are being used in the study to determine if one has more antimicrobial and antibacterial properties, Adhikari said.

The film is edible and has other applications such as breath strips, capsules and binders for tablets.

In addition to using the extract to combat bacteria, pecan growers are already using hot water as a way to treat the in-shell pecans to minimize kernel breakage during shelling.

“This study of using hot water treatments will be an ongoing research project,” Adhikari said. “We recently hosted a group from Mexico that is interested in using the hot water treatment in their pecan processing facilities.”

“During my master’s study, I looked at how growers are using this treatment,” Kharel said. “Apart from increasing the shelling efficiency, hot water treatment could be an effective way to reduce pathogens that may contaminate the pecans that have fallen on the ground before harvesting.”

Part of her research is to standardize the temperature and time needed to treat the pecans.

Jonathan Hubchen, assistant director of the AgCenter Global Network, said the program that funded her stay in Poland is called PROM, which is a European Union-financed program for doctoral students worldwide.


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