Tag Archives: The Abstract

NC State researchers show copper affects norovirus capsid

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Matt Shipman, public information officer at NC State University and curator of The Abstract writes, norovirus affects an estimated 20 million Americans every year, and the hardy virus can linger on exposed surfaces for weeks – making it difficult to stop the spread of the disease. But a new finding from NC State researchers shows that an age-old commodity may be a new tool in combating norovirus: copper.pennies-435cs051012-1

The researchers found that viral shells (being used as a stand-in for norovirus) that were in contact with copper alloys for at least ten minutes became effectively neutralized. In other words, the finding means that virus particles that land on a copper doorknob or counter-top would no longer be capable of causing a norovirus infection.

The work holds promise for helping to limit the spread of norovirus infection via “environmental contamination” in places like hospitals or doctor’s offices.

A paper on the finding, “Destruction of the Capsid and Genome of GII.4 Human Norovirus Occurs During Exposure to Metal Alloys Containing Copper,” is published online in the journal Applied and Environmental Microbiology. The paper was authored by NC State researchers Chip Manuel, Matt Moore, and Lee-Ann Jaykus, who are part of the NoroCORE research collaborative. NoroCORE stands for the Norovirus Collaborative for Outreach, Research, and Education, and involves more than 30 research teams from 18 institutions. It is funded through a $25 million grant awarded by the USDA National Institute of Food and Agriculture.

More information on the work is also available on the site of the American Society for Microbiology.

If Eggnog Has Eggs In It, Why Is It Safe To Drink?

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Continuing with the egg-in-drink and holiday food safety trend, I had a chat last week with my friend Matt Shipman about eggnog. Matt, a science writer, public information officer at North Carolina State University, curator of The Abstract, and all around swell dude, writes:

Eggnog is a holiday treat, but it contains – surprise! – eggs. So how come it’s okay for us to drink it? Here are a few questions and answers about eggnog and food safety.

If eggnog has eggs in it, and eggs can carry Salmonella, why is it safe to drink eggnog? The eggs aren’t cooked, are they?

Actually, they are.Eggnog-848x477

“If you’re buying eggnog at the store, the beverage has likely been pasteurized,” says Ben Chapman, a food safety expert and researcher at NC State. “That means the egg-and-milk combination has been heat-treated to kill most of the harmful microorganisms that could make you sick, and reduce the ones that cause spoilage as well.”

Is it safe for me to make my own eggnog?

“Using regular eggs is risky, but you could use pasteurized eggs or egg products,” Chapman says. “Or you could effectively pasteurize your own eggs by slowly bringing the eggnog ‘base’ to 160 °F. The FDA offers advice on how to do that safely.”

Can I use alcohol to make my eggnog safe to drink, or to store at room temperature?

Only if you like really strong eggnog.

“Ethanol, the alcohol in beverages, should kill some of the pathogens that might be there,” Chapman says. “But the eggnog would still be subject to spoiling, as other hearty microorganisms can multiply and create off flavors.”

Chapman says that using alcohol as a protective measure isn’t a simple venture. Although wine and other clear alcoholic beverages haven’t been linked to foodborne illnesses, a 2010 investigation into exactly what components were protective in wine showed that ethanol on its own wasn’t enough.

Chapman says that in that particular experiment, ethanol provided a 1.5 log (that’s between 90 and 99 percent) reduction in Salmonella in 24 hours. That’s not good if you’re looking to make and serve eggnog, particularly since no reduction in pathogens was seen within the first 60 minutes after adding alcohol. “The cream also complicates things in eggnog as it has fat in it – and high fat environments like peanut butter and chocolate serve to protect Salmonella cells,” Chapman says.

What’s the deal with ‘aged’ eggnog?

You may be familiar with stories that have made the rounds about “aged” eggnog, and how it’s safe to drink eggnog containing raw eggs if you let it hang around for a few weeks. Many of these stories trace back to an experiment done at Rockefeller University (you can hear Science Friday’s 2008 story on it here). There are (at least) two things worth noting about the Rockefeller eggnog.

First, based on the recipe that accompanies that story, and some quick back-of-the-envelope calculations, the eggnog in question was ~14 percent alcohol – which may be high compared to many festive drinks. Second, the eggnog was refrigerated during the aging process. The cold temperature helps to limit microorganism growth and the hold time allows for the ethanol to penetrate and to act on the cells.

Chapman notes one other issue with the Rockefeller University data – it’s anecdotal. “Although it has made the rounds in the media as an answer to the holiday party drink favorite, the study hasn’t been evaluated by peer review.” Chapman goes on to say, “While it appears this specific recipe might work, we also don’t know what the threshold for alcohol content and egg/milk ratios would lead to similar Salmonella destruction. For example, whether an eggnog with 9 percent alcohol held in the fridge for one week would be safe.”

Fast Facts about Cutting Boards and Food Safety in Your Kitchen (from The Abstract)

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Channeling my inner Dean Cliver, I had a chat last week with my friend Matt Shipman about cutting boards and food safety. Matt, a science writer, public information officer at North Carolina State University, curator of The Abstract, and all around swell dude, writes:

Anything that touches your food can be a source of contamination and foodborne illness – including cutting boards.

For example, if you cut up a raw chicken, and then use the same cutting board to slice a tomato for your salad, you run the risk of cross-contamination – with bacteria from the chicken being transferred to the tomato. That, of course, would be bad.

And vegetarians aren’t off the hook either. Fruits and vegetables can also carry pathogens (and transfer them to cutting boards).

To reduce the risk of foodborne illness in your kitchen, here are some things you should know about cutting boards.

Plastic Versus Wood

For a long time, most (if not all) cutting boards were made of wood. But at some point people began using plastic cutting boards. The idea was that they were easier to clean (and sanitize), and therefore were safer.

But in the late 1980s, a UC Davis researcher named Dean Cliver – the de facto godfather of cutting board food safety – decided to investigate whether plastic cutting boards really were safer. Answer: not really.

Photo credit: Betsssssy, via Wikimedia Commons.

Plastic cutting boards, Cliver found, are easier to sanitize. But cutting on them also leaves lots of grooves where bacteria can hide. Wood is tougher to sanitize, but it’s also (often) tougher in general – you won’t find as many deep scratches in the surface.

In addition, researchers have discovered that the type of wood your cutting board is made from also makes a difference.

“Hardwoods, like maple, are fine-grained, and the capillary action of those grains pulls down fluid, trapping the bacteria – which are killed off as the board dries after cleaning,” says Ben Chapman, a food safety researcher at NC State. “Soft woods, like cypress, are less likely to dull the edge of your knife, but also pose a greater food safety risk,” Chapman explains. “That’s because they have larger grains, which allows the wood to split apart more easily, forming grooves where bacteria can thrive.”

Which type of cutting board should you use? Chapman recommends using plastic cutting boards for meat and wood cutting boards for fruit, vegetables, or any ready-to-eat foods (like bread or cheese).

Why use plastic cutting boards for meat? Because of how you wash them.

Cleaning Your Cutting Board

Plastic and wood have different characteristics, so you have to handle them differently.

Plastic cutting boards can be placed in the dishwasher, where they can be sanitized by washing at high temperatures. But wood cutting boards would quickly be ruined by a dishwasher, and not everyone owns a dishwasher. If you’re washing a cutting board by hand, you should:

  • Rinse the debris off the cutting board (being careful not to splatter contaminated water all over the place);
  • Scrub the cutting board with soap and water (to get out anything in the scratches or grooves on the board’s surface); and
  • Sanitize the cutting board (you should use different sanitizers for wood cutting boards than for plastic ones).

For plastic cutting boards, you should use a chlorine-based sanitizer, such as a solution of bleach and water (one tablespoon of bleach per gallon of water – has a shelf life of a week or two). But for wood cutting boards, you should use a quaternary ammonia sanitizer, such as a solution of Mr. Clean and water (follow the dilution instructions on the label).

“This is because chlorine binds very easily to organic materials, like the wood in a cutting board, which neutralizes its antibacterial properties,” Chapman says. “Quaternary ammonia is more effective at killing bacteria on wood or other organic surfaces.”

It’s worth noting that you should also sanitize your kitchen sponge/rag/brush after you’ve used it to scrub the chicken-juice off your cutting board – or else you run the risk of contaminating the next thing you wash (which is the exact opposite of what you’re trying to do).

The last step in cleaning your cutting board is an important one –dry it.

“Make sure you put the cutting board somewhere that air circulates, so that it can dry completely,” Chapman says. Bacteria need moisture to grow, and you don’t want to give them a welcoming environment.

“Historically, butchers used to put salt on their butcher blocks to keep them from smelling bad,” Chapman says. “This worked because the salt drew the moisture out of the wood and prevented bacterial contamination, which is what caused the smell – though the butchers didn’t know it at the time.”

When To Replace Your Cutting Board

At some point, scrubbing and sanitizing might not be enough. When your cutting board has accumulated a lot of deep grooves from repeated use, you probably need to replace it.

“The more grooves it has, and the bigger they are, the more area is available for trapping moisture and giving bacteria a place to proliferate,” Chapman says.