Researchers in China report that air plasma can be used to kill biofilms found on the surfaces of perishable fruits and foods — significantly extending their shelf life, and reducing the world’s ‘food waste’ problem as well
Seeing fruit “turn bad and going to waste” inspired a team of researchers in China to explore using atmospheric pressure nonequilibrium plasma — already widely used for medical purposes — as a novel solution to extend the shelf life of fruit and other perishable foods.
When bacteria attaches to food surfaces, it can extract nutrients and continue to proliferate in the form of “biofilms.” Bacterial biofilms on food and food-processing surfaces diminish the food’s quality and safety.
But plasma sources are capable of killing bacteria such as Salmonella and E.coli on apples, as well as other types of spoilage microorganisms on mangos and melons, and Listeria on meat.
Now, researchers from China’s Shanghai Jiao Tong University and Huazhong University of Science and Technology report this week in the journal Physics of Plasmas, from AIP Publishing, about their computational study of how air plasma interacts with bacterial biofilms on an apple’s surface suggests that plasma technology could be used to decontaminate food in the future.
The fundamental concept behind the team’s work is to harness the reactive species generated by plasma to kill bacterial biofilms, which are notoriously difficult to wipe out.
“A biofilm consists of groups of microorganisms in which cells stick to each other, and these cells often adhere to a surface,” explained Xinpei Lu, a professor in the College of Electrical and Electronic Engineering at Huazhong University of Science and Technology. “These adherent cells are frequently embedded within a self-produced matrix of extracellular polymeric substance, which forms in different shapes and acts to protect the bacteria.”
For this work, the team simulated how the structure of the biofilm affects the discharge dynamics and then zeroed in on how the reactive species generated by the plasma are distributed on the biofilm’s surface — because it can later kill the bacteria within the biofilm.
“Plasma is formed when enough energy is added to a gas to ‘free up’ electrons from a significant number of atoms or molecules,” Lu said. “This process, known as ‘ionization,’ creates a mixture of positively charged particles, negatively charged particles, and various uncharged particles.”
High concentrations of so-called free radicals — very chemically reactive atomic or molecular fragments — often exist among these particles.
“These free radicals can quickly overwhelm the natural defenses of living organisms, which leads to their destruction,” he added.
Because plasma can easily produce more than a trillion free radicals per cubic centimeter of volume, it can serve as an efficient decontamination agent.
“Free radicals are one type of germ-killing agent generated via plasmas,” Lu pointed out. “Plasmas also produce other agents such as ultraviolet light, which sterilizes by causing DNA damage.”
Scientists previously observed that bacterial cell membranes sometimes rupture when exposed to plasma. This may be caused by charged particles attaching to the outer surface of the cell — inducing an electrostatic force that can overcome the tensile strength of the cell’s membrane by rupturing it.
So the team decided to explore how plasma interacts with biofilms and how the reactive species generated by the plasma are able to penetrate the cavity of the biofilm.
“Technically, we wanted to simulate the discharge (in millimeter gap distance) while capturing the effect of the biofilm’s mushroom shape (within a micrometer range) — an extremely challenging task,” said Lu.
What did they find?
“We discovered that the structure of the biofilm results in non-uniform distribution of reactive species during the plasma-on period,” he explained. “The mean free path of charged species at micron-scale permitted the plasma to penetrate into the cavity of the biofilm. This means that although the density of reactive species decreased by 6 to 7 orders of magnitude, the diffusion caused a uniform distribution of reactive species inside the cavity during its pulse-off period.”
In terms of applications, the team’s work indicates that air plasma can be used to kill bacteria within biofilms, which could “significantly prolong the amount of time fruit remains edible,” said Lu. Such a technique could be on the market within a few years, “once a low-cost plasma source is developed.”
The next step toward using low-temperature plasma technology for the decontamination of fruit is “to generate a uniform plasma over the irregular surface of the fruit, or to use a plasma jet to scan the surface of the fruit,” Lu noted. “We’re currently working on the latter method to achieve this goal.”
The Latest on: Air plasma
via Google News
The Latest on: Air plasma
- Strong winds power electric fields in the upper atmosphere, NASA’s ICON findson November 29, 2021 at 1:42 pm
Using observations from NASA’s ICON mission, scientists presented the first direct measurements of Earth’s long-theorized dynamo on the edge of space: a wind-driven electrical generator that spans the ...
- Welders cause bazaar sensationon November 29, 2021 at 12:10 pm
Welders Robyn Nearing and Wes Meinzer caused a traffic jam at a recent holiday craft bazaar. The Russiaville couple own and operate RustyBloomers. And their sculptures and décor made from scrap metal ...
- Highland Newson November 29, 2021 at 4:27 am
Nov. 28, is the first Sunday in Christmas Advent. The focus was on Hope. Where would we be without Hope--especially without hope in our Lord Jesus Christ. I ...
- Ozone Generation Market– Snapshot on Global Benefits 2026on November 29, 2021 at 12:41 am
Global Ozone Generation Market was valued US$ $830.54 in 2017 and is expected to reach US$ $1600.26Mn by 2026, at a CAGR of 8.55 % during a forecast period Global ozone generation market is segmented ...
- Re-wearing gym gear and zapping clothes with plasma: My week of sustainable laundry swapson November 28, 2021 at 10:00 pm
While buying fewer clothes is a vital part of developing a more sustainable approach to fashion, the items we already own are wreaking havoc on the environment every time we wash them. Sophie Benson s ...
- Strong winds power electric fields in the upper atmosphereon November 28, 2021 at 4:00 pm
Using observations from NASA's ICON mission, scientists presented the first direct measurements of Earth's long-theorized dynamo on the edge of space: a wind-driven electrical generator that spans the ...
- Axios Retracts COVID-19 Air Filters Story: ‘It Fell Short of Our Editorial Standards’on November 24, 2021 at 7:52 am
Axios retracted a Nov. 17 story about air filters and COVID-19, saying “it fell short” of the political outlet’s editorial standards. “Axios has removed the article published here on Nov. 17, 2021, ...
- School Teachers Nationwide Are Concerned About Air Quality in Classrooms - But Many Are Turning Down or Off In-Room Air Purifiers Due to Noiseon November 23, 2021 at 4:30 am
A new national survey of K-12 teachers, commissioned by Global Plasma Solutions, shows that more than two-thirds are turning down or ...
- Global Air Plasma Spray Equipment Market 2021 Leading Segments, Primary and Secondary Drivers, Key Players and Geographical Analysis by 2027on November 16, 2021 at 1:21 pm
A research study conducted on Global Air Plasma Spray Equipment Market Research Report 2021-2027 offers substantial information about market size and estimation, market share, growth, and product ...
via Bing News