Yes, Double-Dipped Chips Can Spread a Large Number of Germs
Ever since Seinfeld tackled the topic in 1993, we have known that double diving is unpleasant for society. But is this really a real way of spreading disease-causing microbes? Of course there is.
A professor of food science at Clemons University decided to test the semi-obvious theory that double dipping, the process of placing a chip in a dish, taking a bite and then dipping it again, is unsanitary. Result? In some cases, bacteria levels were significantly higher than in double-dipped bowls. Even more surprising, the number of bacteria varied depending on which type of paste was used:
We found that in the absence of double dipping, there were no detectable bacteria in our products. After double dipping, salsa captured approximately five times more bacteria (1000 bacteria / ml sauce) from the bitten chip compared to chocolate and cheese sauce (150-200 bacteria / ml sauce). But two hours after the double dipping, the salsa bacteria count dropped to about the same level as in chocolate and cheese.
Although salsa tends to absorb more bacteria than chocolate or cheese sauces, this level also declines more quickly over a two-hour period. Presumably, the acidity of salsa can kill more bacteria, but it takes time. In any case, if someone you know gets sick and shares a meal, don’t let them dip twice, unless everyone in the room wants to get sick.
Is double dipping a food safety issue or just a nasty habit? | Conversation through a raw story