A night out wolfing down shellfish at an open buffet has been blamed for stomach upsets, but a new study is casting a favorable light on crustaceans for their role as protectors against common food poisoning.
Chitosan, a natural carbohydrate derived from shells of crustaceans such as shrimps, lobsters and crabs, is showing promise as a weapon against a bacterium, Clostridium perfringens, blamed for the second-most common bacterial food-borne illness in the United States, after salmonella poisoning.
The substance, which results from treating the exoskeletons of crustaceans with an alkaline compound, is the subject of a recent study by professor of microbiology Mahfuzur Sarker in the Oregon State University (OSU) colleges of science and veterinary medicine and OSU graduate student Maryam Alnoman.
The findings, published in Food Microbiology, show that chitosan is able to block C. perfringens growth in cooked chicken.
Present in soil, decaying vegetation and the intestinal tracts of vertebrates, C. perfringens typically infects humans when they eat meat that has not been thoroughly cooked or properly stored, allowing the bacteria to multiply.
It produces tough, metabolically dormant spores that are able to survive many food processing approaches.
Oysters on the grill / CFP Photo
Symptoms of C. perfringens food poisoning include abdominal pain, stomach cramps, diarrhea and nausea.
While the bacterium annually sickens more than a million people in the United States, patients often mistake it for a 24-hour flu.
"People aren't dying, but they're getting sick," said Sarker.
"And many times people don't report it, so there are likely way more people getting infected than we know about."
The research involved both laboratory growth medium, namely bacteria in solution, and cooked, contaminated chicken meat left for several hours at 37 degrees Celsius. It looked at the full life cycle of the C. perfringen bacterium.
In addition to blocking C. perfringens growth in cooked chicken, chitosan was found to inhibit spore germination and outgrowth, block the spore core from releasing dipicolinic acid, which is associated with an early step of spore germination, and limit the growth of vegetative cells, which are actively growing as opposed to producing spores.
Clams, mussels, oysters, shrimps, lobsters and crabs are all part of the Shellfish group. / CFP Photo
"In lab conditions, low concentrations of chitosan were effective. In meat, the concentration needs to be higher because there are a lot of ingredients in the cooked meat that can inhibit the activity of the antimicrobial chemicals," Sarker was quoted as saying in a news release from OSU.
"But the larger dose of 3 milligrams per gram of food is still a good dose that can be used in making food products."
Sarker said this is the first time chitosan was shown to work consistently both in lab conditions and in chicken meat, noting that the next step is to research chitosan's effectiveness in other types of meat and meat products and optimize the conditions for using it.
It is possible, for example, that chitosan may work best when combined with other food preservative chemicals such as sorbate and benzoate.
"It could be a combination of multiple agents," he said, "there are options we can try."
(Source: Xinhua)
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