Composed of apple puree and oregano oil, which acts as a natural antibacterial agent, the coating shows promise in laboratory studies of becoming a long-lasting, potent alternative to conventional produce washes, according to a team of scientists from the U.S. Department of Agriculture (USDA) and the University of Lleida in Spain.
The study comes on the heels of the recent deadly E. coli outbreak in spinach and amid growing concern by experts that some produce-cleaning techniques may not be effective in destroying E. coli. The study is scheduled for the Nov. 29 issue of the American Chemical Society's Journal of Agricultural and Food Chemistry.
"All produce-cleaning methods help to some degree, but our new coatings and films may provide a more concentrated, longer-lasting method for killing bacteria," says Research Leader Tara H. McHugh, Ph.D., a food chemist with the USDA's Agricultural Research Service in Albany, Calif. As the films are made of fruit or vegetable puree, they also provide added health benefits such as vitamins, minerals and antioxidants, she says.
Researchers have known about the antimicrobial activity of plant-derived essential oils for some time, but McHugh says that her group is the first to incorporate them into a fruit- or vegetable-based edible food wrap for the purpose of improving food safety. Three years ago, she and her associates developed a similar edible food wrap, but without the antimicrobial properties.
The new antimicrobial coatings have not been tested on fresh produce yet, McHugh notes. The current study only tested the coatings against E. coli O157:H7, a potentially deadly strain of the common bacterium Escherichia coli, but tests on other foodborne pathogens, including Salmonella, are ongoing or planned in the future, she says. If they continue to show promise, the coatings could hit the consumer market in a year or two, estimates McHugh, whose study is funded by the USDA.
In developing the coatings, McHugh and her associates tested oregano, cinnamon and lemongrass oils in solutions of apple puree and dried films for their effectiveness against E. coli. Each compound was tested in a controlled series of dilutions, the scientists say.
While all of the oils tested inhibited the growth of E. coli, oregano oil was the most effective, killing over 50 percent of sample bacteria in 3 minutes at concentrations as small as 0.034 percent, says McHugh, who's now working on improving the kill rate.
The second most effective oil was lemongrass, followed by cinnamon oil. By contrast, the apple-puree film alone did not kill the E. coli bacteria, the scientist says.
However, an advantage of the apple antibacterial film is that it is composed of sticky sugars and lipids, which allow the coating to adhere to fruits and vegetables for longer periods than conventional, water-based produce washes. That same stickiness also gives the suspended antimicrobial agents a more concentrated exposure to bacterial surfaces, increasing the film's germ-killing potential, the researchers say.
The antibacterial coating could be used by produce manufacturers as a spray or dip for fresh fruits and vegetables, they say. The resulting product will taste a bit like oregano, McHugh says, adding that this can be a desirable trait in salads.
Besides apple puree, the antimicrobial films can also be made from broccoli, tomato, carrot, mango, peach, pear and a variety of other produce items. Non-antimicrobial versions of these food wraps are now being made commercially by California-based Origami Foods® in cooperation with the USDA for use in a small but growing number of food applications, including sushi wraps.
Michael Bernstein | EurekAlert!
Zap! Graphene is bad news for bacteria
23.05.2017 | Rice University
Discovery of an alga's 'dictionary of genes' could lead to advances in biofuels, medicine
23.05.2017 | University of California - Los Angeles
An international team of physicists has monitored the scattering behaviour of electrons in a non-conducting material in real-time. Their insights could be beneficial for radiotherapy.
We can refer to electrons in non-conducting materials as ‘sluggish’. Typically, they remain fixed in a location, deep inside an atomic composite. It is hence...
Two-dimensional magnetic structures are regarded as a promising material for new types of data storage, since the magnetic properties of individual molecular building blocks can be investigated and modified. For the first time, researchers have now produced a wafer-thin ferrimagnet, in which molecules with different magnetic centers arrange themselves on a gold surface to form a checkerboard pattern. Scientists at the Swiss Nanoscience Institute at the University of Basel and the Paul Scherrer Institute published their findings in the journal Nature Communications.
Ferrimagnets are composed of two centers which are magnetized at different strengths and point in opposing directions. Two-dimensional, quasi-flat ferrimagnets...
An Australian-Chinese research team has created the world's thinnest hologram, paving the way towards the integration of 3D holography into everyday...
In the race to produce a quantum computer, a number of projects are seeking a way to create quantum bits -- or qubits -- that are stable, meaning they are not much affected by changes in their environment. This normally needs highly nonlinear non-dissipative elements capable of functioning at very low temperatures.
In pursuit of this goal, researchers at EPFL's Laboratory of Photonics and Quantum Measurements LPQM (STI/SB), have investigated a nonlinear graphene-based...
Dental plaque and the viscous brown slime in drainpipes are two familiar examples of bacterial biofilms. Removing such bacterial depositions from surfaces is...
23.05.2017 | Event News
22.05.2017 | Event News
17.05.2017 | Event News
23.05.2017 | Physics and Astronomy
23.05.2017 | Life Sciences
23.05.2017 | Medical Engineering