Could sharing ketchup over french fries be an 'indirect kiss?'

Sharing french fries with a friend can sometimes lead to an unexpected moment: you bite into the fry, then dip it back into the communal ketchup. This seemingly harmless act, often done among close friends, has earned a playful nickname – an "indirect kiss." The humor behind this may have a kernel of truth, as researchers have found that bacteria from the mouth can indeed transfer into shared sauces during the double dip.

The act of double dipping, where someone takes a bite and then plunges the food back into a shared sauce, has been studied by researchers at Clemson University in the United States. Their findings, published in the Journal of Food Safety, confirm that bacteria from the mouth can make their way into the communal ketchup. While it may seem like a casual act, the study reveals that double dipping can transfer a significant amount of oral bacteria.

According to the research, it would take around 800,000 instances of double dipping to transfer a similar amount of bacteria as a 10-second kiss. This comparison highlights just how many double dips would be needed to achieve a bacterial exchange comparable to a kiss. While the practice may be harmless in social settings, the study underscores the presence of oral bacteria that can be shared through this seemingly innocuous act.