Abstract
The purpose of this research was to determine whether double dipping would spread more germs than only dipping once. Through experimental procedures researchers inoculated a sample of salsa onto agar plates that were either doubled dipped from a jar of salsa or were only single dipped from the same jar of salsa. After 48 hours of incubation the plates were examined to see whether the double dipped plate contained more growth compared to the single dipped plate. Examing the growth of the two resulted with the double dipped salsa showed to have double the amount of growth than the single dipped salsa.
Introduction
The very common social blunder, double dipping, is widely unaccepted to proper etiquette because it has been believed that this practice transfers saliva to a dip and causes a spread of germs. The purpose of this experiment is to evaluate whether there is truth to this theory. To test this theory the researchers used the zigzag inoculation technique to get isolated colonies after incubation. Zigzag inoculation is a technique that is exactly what the name is, a bacterial sample is streaked in a zigzag pattern on an agar plate. The nutrient agar plates are a general purpose medium that support growth of a wide range of non-fastidious organisms. Incubation is the process of growing a culture by supplying it with the necessary environmental conditions. With the use of nutrient agar plates and zigzag inoculation techniques the researchers aimed to test whether double dipping chips transferred more bacteria to salsa than single dipping. The researchers hypothesized that there will be more bacterial growth observed from double dipping than compared to single dipping.
Methods
The materials that tested were a sealed jar of salsa, and an unopened bag of tortilla chips. The materials used to test with were three nutrient agar plates and three sterile cotton swabs. The four test subjects used to test the theory were of the same approximate age group and all were in good health. Before experimental procedures the test subjects each washed their hands to alleviate any contamination to the experiment. The researchers first used one of the sterile cotton swabs and dipped the swab into the jar of salsa and used the zigzag inoculation technique on one of the nutrient agar plates. That was labeled as the inoculated control plate. Following the washing of their hands the first test subject took a chip and dipped it into the same jar of salsa as the control and ate it; the following three subjects followed the same procedures until all four subjects had each taken a single dip of salsa from the jar. With the second sterile cotton swab the researchers used the zigzag inoculation technique on the second nutrient agar plate for the single dipped salsa. That was labeled as the single dipped inoculated plate. Following that the first subject got another chip and got a dip of salsa and ate that off; then with the same chip got an addition dip of salsa. Each of the subjects followed the same procedures as the first until each one had double dipped with a single chip. Once the double dipping had been done the researchers used the third sterile cotton swab to zigzag inoculate the third nutrient agar plate. That was labeled as the double dipped inoculated plate. After inoculation of the plates, the plates were placed in an incubator and were incubated at 37°C for approximately 48 hours. After the completion of the incubation period the plates were examined and compared for bacterial growth.
Results
After incubation the three nutrient agar plates were examined for growth. The researchers observed that the control plate had very minimal to no growth at all. The single dipped nutrient agar plate was observed to have a slight-medium amount of growth. The double dipped nutrient agar plate was observed to have twice as much growth compared to the single dipped agar plate. The zigzag inoculation technique produced isolated colonies. The colony morphology was that colony forming units were small in size with an entire margin and round shape. The texture was mucoid and the CFU’s were slightly raised. The researchers’ observations were recorded in
Table 1 below.
Table 1 Observed Growth Bacterial Colonies Interpretation/Morphology ~ 48 hours
Control very minimal growth-to no growth Few CFUs small, round shape, entire margin, mucoid, slightly raised
Single-Dipped slight-medium growth Some CFUs small, round shape, entire margin, mucoid, slightly raised
Double-Dipped lots of growth—twice as much Greater amount of CFUs small, round shape, entire margin, mucoid, slightly raised

Discussion
The experimental procedures that were carried out resulted in the researchers’ hypothesis to be supported, double dipping has more bacterial growth than a single dipped dip. When an individual single dips a chip into salsa, there is not as many germs transferred into the dip. What is transferred is more of a normal amount, however, when a person double dips a chip into the salsa there is more growth. Double dipping germs comes from the individual’s mouth from biting off or even licking off the dip from the chip, then that individual is placing that same chip back into the dip, thus transferring the bacteria from their mouth into the salsa. The transferred bacteria is what the researchers aimed to be able to observe through their research on the double dipped plate. Overall the researchers’ experiment did have a successful outcome in that they were able to support their initial hypothesis through positive experimental data. However, there is always the chance of error in an experiment. The chances of error in this experiment that could have aided in the success of the experiment could have been the researchers not having very good washing hands technique. Having poor washing of hands could lead to having contaminates left on the subjects’ hands which may have possibly increased the bacterial growth. The researchers’ hypothesis was based off of bacterial growth so this chance of error could have possibly given the researchers a false-positive result. Taking all into account though, the researchers’ techniques and experimental procedures showed to support the overall hypothesis that double dipping has more bacterial growth compared to single dipping.