Scientists in Virginia Tech's food science and technology department are currently researching high-pressure processing, or HPP, effectively "squeezing" bacteria to death.
This decontamination method rids produce of harmful bacteria, making healthy fruits and vegetables safe to eat while keeping them fresh and intact.
"There are quite a few products already on the market that utilize the process," said Laura Douglas, manager of the HPP lab at Tech.
Some of these products include salsas, avocado halves, and a number of refrigerated dips, fruit juices and deli meats.
"In a lot of cases it extends shelf life and also makes the food safer," Douglas said.
George Flick, university distinguished professor of food science and technology, added that a few large chain stores sell products treated with HPP, such as Kroger, Wal-Mart and Costco. Some stores in Texas feature foods that have gone through the process. Flick established the HPP lab in Tech's food science department; it was his idea to get the equipment, and he oversees the entire operation along with Douglas.
Douglas explained that the technology works by completely surrounding products, such as tomatoes or jalapenos, with pressure, which effectively kills or inactivates microorganisms.
"Many of the products come out looking almost exactly like when they went in because the water pressure is evenly distributed, so it doesn't just crush the product," Douglas said.
Renee Boyer, associate professor of food science and technology noted that her research now is focused mainly on Salmonella.
"I'm trying to kill Salmonella with HPP and find a way to process fresh produce and still have what would be a fresh product after it's been processed," Boyer said.
Still in the preliminary stages of research, Boyer has run cultures of Salmonella through the HPP machine, finding that the technology is sufficient to kill the bacteria. The objects of her research are red, round tomatoes and chopped tomatoes that go into salsas. She will soon begin to test the process on lab-contaminated products.
"Since we don't know where the organisms come from, she is partnering with horticulture and other departments," said Susan Sumner, departmental head of food science and technology at Tech. "It's unique that she's taking that holistic approach."
Some organisms that are inactivated by this process are Salmonella, Listeria monocytogenes, species of Vibrio and E. coli O157:H7.
Sumner differentiates E. coli O157:H7 from other serotypes because other strains are natural to humans and help to keep our bodies healthy.
Sumner explained that those who are most susceptible to harm from these vegetative pathogens are infants, the elderly and immunocompromised people. Once the contaminated product is ingested, it typically takes 24 to 48 hours for symptoms to develop, and they usually last between three and four days.
Additionally, Sumner said that when people suffer from food poisoning, they tend to think back on what they've eaten the same day when they should really be looking two or three days back.
Amanda Lathrope, manager of the food safety department of the California-based National Food Lab, said that microbial inactivation has a number of factors that go into killing the organism, several of which disrupt membrane bonds and protein confirmation.
"The process is typically pretty effective against vegetative pathogens," Lathrope said.
Douglas said a number of outbreaks of Salmonella have increased interest in HPP.
"The populace is looking at and wanting more natural processing," Douglas said. "HPP doesn't seem to have the bad connotations that other processes do."
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