Dear Helena,

At my office holiday party recently, a co-worker of mine dipped a chip into the guacamole, took a bite, and then dipped the chip again. I was repulsed. Then I looked around and saw lots of people were double-dipping, taking bites of carrot and celery sticks and then plunging them back into the various dips. I thought it was widely known that this is gross. If you need to dip a second time, you should at least reverse the dipped item so the unbitten side touches the dip. Am I wrong?

Dear Single-Dipper,

People frown on double-dipping because they assume it contaminates the dip for everyone else. But does it? Professor Nancy Zeller, director of biology teaching laboratories at American University, conducted a scientific investigation into the matter. Her students double-dipped in five different dips, including salsa and spinach-artichoke. After letting the dips sit for an hour, Zeller tested a sample from each and found negligible amounts of bacteria.

She explains: “When you bite a chip, you don’t put much of your lips on that chip. You tend to bite with your teeth, so you’re not introducing much saliva, which is where the bacteria are.”

Even if the double-dipper does leave behind traces of saliva, many dips are not hospitable to bacterial growth. The dips tested in the experiment, Zeller says, were “processed dips with a lot of additives and salt, which may help to keep bacteria in check.” Rick Rodgers, author of Dip It! Great Party Food to Spread, Spoon, and Scoop, says that although homemade dips don’t have additives, they often have other ingredients that discourage bacteria, including “acidic ingredients, such as vinegar and citrus juices [and] high levels of salt.”

It’s Still Gross

So double-dipping is unlikely to give anyone hepatitis. Nevertheless, many people will have a visceral negative reaction to it. “I would be shocked if someone double-dipped,” says Rodgers. “It’s bad etiquette.” If double-dipping were allowed, then, in his view, it would be a slippery slope to cavemanlike behavior: “Why not just stick your fingers directly in the dip and not use celery at all?”

Rodgers recommends reversing your crudité or chip and dipping the unbitten side, or breaking the item into pieces and dipping each one individually. But I disagree. Even if you do follow Rodgers’s reversal rule, people might not realize you have done so and may suspect you of double-dipping anyway.

A Host’s Responsibility

If you’re hosting a party serving dip, make sure you buy smaller chips, or cut vegetables into small sizes. Cauliflower should be broken into manageable florets, and celery, cucumber, and zucchini should be sliced into batons about the size of a baby-cut carrot.

Many hosts think dips are too unhygienic to serve at parties. Rodgers, a former caterer, says: “When you talk to a caterer, they’ll say dips are a problem because of double-dipping, so they prefer to make hors d’oeuvres.” But if you’re not a team of caterers, crafting individual canapés is a lot of work. Dips are easier. More importantly, they help people connect. Many cultures have a bonding ritual that involves eating or drinking from the same vessel. In parts of South America, people might share a gourd of mate. At your holiday party, you share a tub of hummus.

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