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Fish and shellfish can be contaminated with bacterial pathogens, such as vibrio and salmonella.
Biodegradable film may kill microorganisms on seafood
UNITED STATES
Wednesday, December 19, 2018, 02:40 (GMT + 9)
A group of researchers found that a biodegradable, edible film made with plant starch and antimicrobial compounds may be used to control the growth of foodborne pathogens on seafood.
Seafood may be contaminated with bacterial pathogens, such as vibrio and salmonella, which are linked to gastrointestinal problems when consumed. Because both types of bacteria can survive long-term freezing conditions, the contamination of these bacteria is a concern for the seafood industry.
(Credit: Goran Bogicevic)
In this regard, professor of food science at Penn State university Catherine Cutter highlights that freezing does not kill bacteria but it may be helpful. She explained that when freezing food, ice crystals can form from the water in food and can act like "daggers" and pierce the bacterial cell wall, causing damage to the cell.
"Vibrio and salmonella are somewhat susceptible to freezing," said Cutter. "So, if you treat bacterial cells with antimicrobials and then freeze them, the approach can be more lethal."
Some researchers from Thailand, who participated in the project, used a blend of thermoplastic starch, a biodegradable polymer made from cassava -- tapioca powder, and a gelatin coating containing antimicrobials known as Nisin Z and lauric arginate (LAE).
Then they created a "culture cocktail" of the bacteria and inoculated slices of tiger prawn and big-eye snapper. The experimentally-inoculated seafood samples were tested using different compositions of Nisin Z and LAE to see which variations would give the "best kill."
Cathy Cutter at Penn State University
After dipping the samples into the edible film composed with antimicrobials, some of the slices were vacuum packaged and chilled for up to a month, and other samples were frozen for 90 days.
Cutter emphasizes the importance of a "controlled release" of the antimicrobials over time in order to get the "maximum kill," which is made possible by the edible film's unique properties. Applying just the antimicrobials directly onto the food products would result in the antimicrobials dripping off or diluting.
Marine pathogens and antimicrobial resistance
"If you're going to make an edible film, you want to make a film that has similar properties to plastic," said Cutter.
"You want these edible films to be transparent because consumers aren't going to buy something they can't see, you want them to be flexible, and you want the film to mold to the food product. By using edible films, you are doing it in a way that is biodegradable," she added.
Cutter said a big challenge that the food industry faces is reducing the reliance on plastic packaging, something the food industry has been using for the past 40-50 years.
"How do you get the industry to change something they and consumers are so used to using?" said Cutter. "This research demonstrates, through proof of concept, that antimicrobial edible films work. So how do we get this type of packaging into a commercial application? That's the next logical step in the progression of this type of research," she concluded.
Source: Penn State
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