A study has found that dipping food that has already been bitten into back into a sauce while several people are gathered to share French fries or snacks can spread bacteria.
A research team at Clemson University compared double-dipping, in which eight participants took a bite of a cracker before dipping it into a sauce, with dipping crackers that had not been bitten into.
The study found that the number of bacteria in the sauce was significantly higher when a bitten cracker was dipped into it than when an unbitten cracker was used. In addition, dipping food that had already been bitten into back into the sauce actually transferred bacteria from the mouth into the sauce. The research team estimated that in situations where several people share food, a single instance of double-dipping could transmit approximately 50 to 100 bacteria between people.
Bacterial survival also varied according to the acidity of the sauce. When the research team dipped bitten crackers into solutions adjusted to pH 4, 5 and 6, the bacterial counts were approximately 3.19 log10 CFU/mL at pH 4, 3.67 log10 CFU/mL at pH 5 and 3.8 log10 CFU/mL at pH 6. The higher the pH, indicating a less acidic solution, the greater the number of bacteria. Even after two hours, the number of bacteria in the pH 6 solution had barely decreased.
Differences were also observed depending on the type of sauce. Immediately after double-dipping, approximately 1000 CFU/mL of bacteria were detected in salsa, compared with approximately 200 CFU/mL in cheese sauce and approximately 150 CFU/mL in chocolate sauce. The research team explained that the acidity and viscosity of the sauces may have affected bacterial survival and transfer.
The research team said, “At gatherings where people share food, avoiding putting food that has already been eaten or shared spoons back into a communal sauce and serving food onto individual plates can help with hygiene management.”
The study was recently published in the international academic journal Journal of Food Safety.
A research team at Clemson University compared double-dipping, in which eight participants took a bite of a cracker before dipping it into a sauce, with dipping crackers that had not been bitten into.
The study found that the number of bacteria in the sauce was significantly higher when a bitten cracker was dipped into it than when an unbitten cracker was used. In addition, dipping food that had already been bitten into back into the sauce actually transferred bacteria from the mouth into the sauce. The research team estimated that in situations where several people share food, a single instance of double-dipping could transmit approximately 50 to 100 bacteria between people.
Bacterial survival also varied according to the acidity of the sauce. When the research team dipped bitten crackers into solutions adjusted to pH 4, 5 and 6, the bacterial counts were approximately 3.19 log10 CFU/mL at pH 4, 3.67 log10 CFU/mL at pH 5 and 3.8 log10 CFU/mL at pH 6. The higher the pH, indicating a less acidic solution, the greater the number of bacteria. Even after two hours, the number of bacteria in the pH 6 solution had barely decreased.
Differences were also observed depending on the type of sauce. Immediately after double-dipping, approximately 1000 CFU/mL of bacteria were detected in salsa, compared with approximately 200 CFU/mL in cheese sauce and approximately 150 CFU/mL in chocolate sauce. The research team explained that the acidity and viscosity of the sauces may have affected bacterial survival and transfer.
The research team said, “At gatherings where people share food, avoiding putting food that has already been eaten or shared spoons back into a communal sauce and serving food onto individual plates can help with hygiene management.”
The study was recently published in the international academic journal Journal of Food Safety.