Ever since Seinfeld tackled the topic in 1993, we've known that double-dipping is socially unsavoury. But is it really a viable way for disease-carrying germs to spread? Well, of course it is.
Professor of Food Science at Clemons University decided to test the semi-obvious theory that double-dipping — that is, the act of placing a chip in some kind of dip, taking a bite, and dipping it again — is unsanitary. The result? In some cases, the bacteria level was considerably higher than non-double-dipped bowls. More surprisingly, the amount of bacteria varied based on what kind of dip was used:
We found that in the absence of double-dipping, our foods had no detectable bacteria present. Once subjected to double-dipping, the salsa took on about five times more bacteria (1,000 bacteria/ml of dip) from the bitten chip when compared to chocolate and cheese dips (150-200 bacteria/ml of dip). But two hours after double-dipping, the salsa bacterial numbers dropped to about the same levels as the chocolate and cheese.
While salsa tended to take on more bacteria than chocolate or cheese dips, this level also dropped faster over a two hour period. Presumably the acidity of the salsa can kill more bacteria, but this takes time. Either way, if someone you know is sick and sharing food, don't let them double-dip, unless everyone in the room wants to get sick.
Is double-dipping a food safety problem or just a nasty habit? [The Conversation via Raw Story]