A Moment of Science

Double Dipping…Is It Really So Bad?

Have you ever double-dipped? It's not a big deal... right???

Sign that says

Photo: Peyri Herrera (Flickr)

It's a good idea to remind people NOT to double dip. Double dipping can help spread harmful bacteria.

You’re at a party. You grab a big crunchy potato chip and dip it into a dish of creamy onion dip.

But now you’re left with half of a chip with no dip on it. You look at the half eaten chip. You glance around the room to see if anyone is watching.

Should You Dip It Again?

Before you give in to the temptation to double dip that chip, consider the findings of a study done at Clemson University on the effect of pre biting a chip on bacterial transfer to the dip, a.k.a. “double dipping”.

Eight volunteer “chip dippers” dipped chips and crackers into different dipping solutions three to six times. Half the dippers bit the chip once between dips, the others re dipped unbitten chips or crackers.

Dips included cups of sterile water as well as commercial dips of different consistencies and with different common ingredients, like nacho cheese, chocolate, and salsa.

The Results?

Without question, double dipping significantly contaminated the dip with oral bacteria.

After three dips of an unbitten chip or cracker there were fewer than 800 bacteria in the dip. But after three dips by a pre bitten chip, the bacterial levels in the dip shot up to 500,000 per cup!

Contributing Factors

Several factors contributed to just how much bacteria ended up in the dip. Higher acid dips inhibited bacteria initially, but after sitting for two hours the acidic dip was just as high in bacteria as the more neutral dips were.

Dip viscosity also influenced bacteria transfer. Thicker, stickier dips meant that more of the dip that touched the bitten end of the chip stayed stuck to the chip, rather than remaining in the bowl.

The moral of the story? Resist the urge. Don’t be a double dipper!

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