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5 seconds too long: Do's and dont's of food safety


There are good bacteria and there are bad bacteria. No matter which kind gets on food, many people get grossed out by the thought.

Scientists are not certain how these germs are transferred from one place to the next, but research has helped offer some tips to protect from contaminating food.

This week on Take Care, Don Schaffner, a food microbiologist and professor at Rutgers University, shares what he has discovered on the subject as well as a few tips he uses within his own home.

How it transfers

When watching a movie and chomping down on some popcorn, from time to time, a piece will fall to the ground. The reaction of some may be to say, “five-second rule.” However, Schaffner said there is not much truth behind the guideline.

“Let me say the five-second rule is mostly nonsense,” Schaffner said. “In other words, there isn’t some magic time below which you have no bacterial transfer and above which you do have bacterial transfer.”

Now, Schaffner did confirm speed plays a role in the amount of bacteria transfer, but that is in conjunction with the amount of moisture on the surface food falls on.

Research in labs, including Schaffner’s, has shown indications that moisture may be a leading factor in the transfer. The microorganisms tend to follow it.

When wet food drops on a dry surface, the wetness of the food activates the bacteria on the surface despite its previous state. The same holds true for dry food falling on a wet surface. Also, the longer the food remains in the bacteria, the more transfer that occurs.

That being said, some bacteria seem to transfer to the food quicker than others. Scientists are still trying to understand why that’s the case.

Beyond moisture, Schaffner believes the texture of the surface food falls on is important to the transfer of bacteria. The movement will vary whether it’s carpet, wood and tile.

The reality is bacteria has a greater ability to seep into a carpet than wood or tile so less of it will be on the surface of the material as time goes on. Depending on when the food falls, fewer germs will be there to activate on a carpet.

Cutting board safety

Surface texture is also a key factor to consider when it comes to cutting boards. The FDA and USDA both recommend not using wooden cutting boards when cutting meat and poultry.

There has been some conflicting research about the use of wooden surfaces with meat.

“There’s been some research done by my colleague Dean Cliver at UC Davis, since passed away, who showed there’s actually less transfer than we thought from wooden cutting board because maybe bacteria seep down into the cutting board or maybe natural compounds in the wood help to kill bacteria,” Schaffner said.

Nevertheless, Schaffner said the wooden cutting board in his house is used almost exclusively for slicing bread. For the meats, they stick to plastic.

He also pointed out that he never uses the same board for raw meat and poultry as he does for vegetables or something that will not be cooked unless it is washed in between.

When it comes to cleaning cutting boards, Schaffner offered several options:

  • In his home, they will run the boards through the dishwasher, especially on the sanitization cycle
  • A bleach mixture can also be used, but he said it is important to follow the directions on the label to make sure to get the right concentration
  • An affordable option that Schaffner will use at times is simply boiling water in a tea kettle and then pouring the water all over the board

Cleaning meats

Schaffner’s colleague at Drexel University, Jennifer Quinlan, recently did research on the proper way to clean meat and poultry and the dangers of doing so improperly.

The study showed that rinsing in the sink to wash off the meat before cooking will create splatter which transfers contaminants from the food to the area in and around the sink. In fact, washing off the meat will not do enough good to make the risk worth it.

“Do not wash it. Do not dump it in the sink,” Schaffner said. “Take that waste, put it right into the trash and then just cook it. You’re not going to wash off enough bacteria to make a difference and all you’re really doing is spreading those bacteria around your kitchen.”

Taking all these precautions is particularly important for households with member who are more susceptible, such as babies, the elderly and people undergoing treatment for diseases like cancer. But, Schaffner said for everyone it is better to be safe than sorry.