After the novel coronavirus first emerged and sparked a historic global pandemic, one question that naturally comes to mind is how the virus spreads.
One possibility is that humans contract the virus from touching contaminated surfaces, a possibility that has sparked mass deep cleanings, frenzied purchases of hand sanitizer, and doubts about the safety of opening the mail or unpacking groceries without sanitizing them.
Now, new research by the UK’s Food Standards Agency (FSA) into whether viruses can survive on grocery surfaces shows that careful handling of certain foods may not be such a wild idea.
The team said the foods they examined were “commonly sold loose in supermarkets or uncovered at deli counters or market stalls, these foods can be difficult to clean, and are often not processed further, such as re-cooked, before consumption. “
They also examined packaging materials that are extremely common or used in foods that require direct contact between the mouth and the packaging.
Scientists artificially coated food and packaging surfaces with the infectious new coronavirus and studied how the amount of virus on food and packaging surfaces changed over time. During the study, the scientists tested the surfaces in different temperature and humidity environments based on common storage conditions.
The concentration of virus smeared on the surface of the product represents the respiratory droplets that may fall on the surface of the product when an infected person coughs or sneezes nearby.
The researchers found that the virus survived differently on different groceries, but most of the foods they tested showed a “significant decrease” in contamination levels after 24 hours.
Infectious viruses were found days after being contaminated on items such as bell peppers, bread, ham and cheese. On surfaces such as croissants, the virus is alive and transmissible for a few hours.
The study authors summarized the findings by food type.
fruit and vegetable
Scientists at the Food Standards Agency said previous research had shown that COVID-19 was more likely to survive cold temperatures than the ambient temperatures where food was stored.
“However, on the surfaces of the fresh vegetables studied in this report, differences in the survival time of the virus at low temperature and ambient conditions were not significant,” they said in their report published this week.
They said the virus survived longest, for up to five days, on the surface of broccoli stored at 23 degrees Celsius (75 degrees Fahrenheit) and 31 percent humidity. On the surface of sweet peppers refrigerated at 6 degrees Celsius, the new coronavirus can survive for up to seven days.
How long the virus survives on raspberry surfaces depends on storage conditions, but the report’s authors say the raspberry’s uneven surface “may protect the virus from dehydration.” Citing previous research, the researchers said chemicals in the peel of apples give them antiviral properties.
Baked Goods & Treats
The study found that the new coronavirus survived longer on the surface of white bread than on the surface of black bread. The researchers speculate that this may be due to substances in the fiber that is higher in brown bread.
The researchers said the snacks they tested, including croissants and chocolate bread, were able to quickly inactivate the virus. The researchers speculate that this may be due to the coating of egg liquid on the surface of baked goods, which may have an inhibitory effect on the new coronavirus.
The researchers said: “Eggs are one of the foods with the highest arachidonic acid content in the human diet. Studies suggest that arachidonic acid and other unsaturated fatty acids rich in eggs may have antiviral effects.”
Delicatessen
The study found that the survival rate of the virus on the olive surface was extremely low, only surviving for one minute after contamination.
Like apples, chemicals on the surface of olives may inactivate viruses, the team noted.
Meanwhile, scientists at the Food Standards Agency say cooked food, which is rich in protein and saturated fat and has a higher water content, supports the virus to survive longer. They point out that previous studies have found that the new coronavirus on the surface of processed meat can survive for 21 days when stored in the refrigerator.
“The prolonged survival of the SARS-CoV-2 virus on the surface of sliced ham and cheddar cheese, which are rich in protein, saturated fat and moisture, suggests that these foods should be handled properly before consumption to avoid contamination,” the researchers said. Viral infection is very important.”
Package
The researchers found that the new coronavirus can survive for up to a week on plastic surfaces and several days on cardboard boxes. The new coronavirus should only survive a few hours, not days, on the surface of an aluminum can, researchers say.
However, they say the food used in the study was artificially contaminated and therefore does not reflect the level of contamination found in grocery stores. They also suggest that viral loads may take less time to reduce to undetectable levels on less contaminated food surfaces.
Experts from the Centers for Disease Control and Prevention (CDC) said that the main mode of transmission of the new coronavirus is that the aerosol containing the virus exhaled by an infected person is inhaled by others or enters the eyes, nose or mouth of others .
Although the CDC also said that in individual cases, the virus can be transmitted through contaminated surfaces, but there is currently no evidence that handling food or eating can transmit the new coronavirus.
The CDC advises: “Follow food safety guidelines when handling and washing fresh produce. Do not wash produce with soap, bleach, fungicides, alcohol, disinfectants, or other chemicals.”
While the Food Standards Agency researchers acknowledged that multiple studies have found the risk of contracting the virus through contaminated grocery items to be “extremely low”, their study suggests that certain food and food packaging materials “may have prolonged exposure to infectious Virus.”
“If the food comes into direct contact with the mouth and mucous membranes, there is a potential for transmission of the virus through contaminated food,” the researchers said, but they noted that the implications of their findings remain uncertain because inhalation of respiratory droplets is considered a risk factor for COVID-19. the main route of transmission. (Fortune Chinese website)
Translator: Liu Jinlong
Reviewer: Wang Hao
When COVID-19 first emerged to cause a historic global pandemic, questions naturally arose about how the virus was spreading.
One possibility was that people were picking it up from contaminated surfaces, a prospect that led to a surge of deep cleaning, panic buying of hand sanitizer, and questions about whether it was safe to open mail or unpack groceries without wiping them down first.
Now, new research from the UK’s Food Standards Agency (FSA) that looked into whether the virus was able to linger on grocery items suggests that being careful with some food items might not be a completely outlandish idea after all.
The foods that were tested, the research team said, “are commonly sold loose on supermarkets shelves or uncovered at deli counters or market stalls, they may be difficult to wash, and they are often consumed without any further processing ie, cooking.”
They also tested food packaging materials that are either very common or used on products where consumption of the food may involve direct contact between the mouth and the packaging.
Scientists artificially applied infectious COVID-19 virus to the surfaces of the foods and packaging, and measured how the amount of virus present on those surfaces changed over time. The surfaces were tested in a range of temperatures and humidity levels over time periods that reflect the typical storage conditions.
The concentration of the virus that was applied to the items was representative of respiratory droplets landing on them, for example if an infected person coughed or sneezed nearby.
The researchers found that virus survival varied between grocery items, but for most of the foods tested they noticed a “significant drop” in levels of contamination after the first 24 hours.
Some goods, including bell peppers, bread, ham, and cheese, had infectious virus detected on them several days after they were contaminated. On some surfaces, like croissants, the virus remained present and transmissible for hours.
The study’s authors broke their findings down by categories of food.
Fruit and vegetables
Scientists at the FSA said that previous research had suggested COVID-19 was expected to survive better at chilled temperatures than at ambient food storage temperatures.
“But for fresh vegetables presented in this report the difference between survival at chill and ambient conditions, is not so clear cut,” they said in the report, which was published this week.
They said the virus survived for the longest time—up to five days—on broccoli when it was stored at 23 degrees Celsius (73 degrees Fahrenheit) with a humidity setting of 31%. Meanwhile, COVID lived on bell peppers for up to seven days when the peppers were chilled at 6 degrees Celsius.
On raspberries, the virus survived for variable lengths of time depending on conditions, but the report’s authors noted that the fruit’s pitted surfaces “may protect the virus from desiccation.” Apples, however, could have antiviral properties because of chemicals in their skin, the researchers noted, citing previous studies.
Baked goods and pastries
According to the study’s findings, COVID-19 lasts longer on white bread crusts than brown bread crusts. They speculated that this could be because of substances found in the higher levels of fiber in brown bread.
Pastries that were tested, including croissants and pain au chocolate, quickly inactivated the virus, researchers said. They hypothesized that this could be due to the baked goods being coated with a liquid egg wash that may have an inhibitory effect on COVID-19.
“Eggs have one of the highest levels of arachidonic acid in the human diet,” the study’s authors said. “It has been suggested that arachidonic acid and other unsaturated fatty acids which are present in high levels in eggs, may serve comp as antiviral. “
Deli items
The study found that the virus had a very low survival rate on olives—even just one minute after contamination.
The research team noted that, as with apples, it was likely chemicals in olive skins inactivated the virus.
Meanwhile, the FSA’s scientists said deli items that were high in protein and saturated fats with a high water content supported longer virus survival—noting that past research had found COVID-19 could survive on processed meets for 21 days in a refrigerator.
“The long survival time of SARS-CoV-2 on sliced ham and cheddar cheese, with their high protein, saturated fat, and water content, highlights the importance of proper food handling to prevent any contamination by virus prior to consumption,” the study’s authors said.
Packaging
The researchers found that COVID was able to survive for up to a week on plastic surfaces, and several days on cartons. The virus was thought to be able to survive on aluminum cans for hours rather than days, they said.
However, they did note that the foods included in the study were artificially contaminated and were therefore not a reflection of contamination levels that might be found in grocery stores. They added that foods with lower contamination levels would require less time for the virus to decline to undetectable levels.
Experts at the Centers for Disease Control and Prevention (CDC) say COVID mainly spreads when an infected person breathes out droplets that contain the virus, which are then inhaled by someone else or find their way to another person’s eyes, nose or mouth.
While the CDC also says the virus can be spread via contaminated surfaces in some cases, the organization says there is currently no evidence that handling or consuming food can spread COVID-19.
“Follow food safety guidelines when handling and cleaning fresh produce,” the organization advises. “Do not wash produce with soap, bleach, sanitizer, alcohol, disinfectant, or any other chemical.”
While the FSA’s researchers acknowledged that several studies had found the risk of infection via contaminated groceries was “extremely low,” their findings had shown that some foods and food packaging material “can sustain infectious virus for a significant length of time.”
“There is the possibility of transmission through contaminated food if the food is in direct contact with the mouth and mucus membranes,” they said, but they noted that the implications of their findings were unclear because inhalation of respiratory droplets was considered to be the main route of COVID infection.
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