How does it work if we blow out the candles on a birthday cake?
Most people may have practiced this old custom themselves: on our birthday we blow out the candles on our birthday cake and make a wish. This tradition could actually have negative consequences for later consumers of the birthday cake. Blowing out the candles causes the number of bacteria on the cake to increase to 1,400 percent compared to a cake on which no candles were blown out.
In their current study, scientists from Clemson University in South Carolina found that blowing out the candles on a birthday cake leads to an extremely high bacterial load. The doctors published the results of their study in the journal "Journal of Food Research."
Experts make artificial birthday cakes
For the new investigation, a birthday cake was made of styrofoam and then covered with a film, which was decorated with candles on the top. Study participants were then asked to eat a slice of hot pizza. This should mimic the type of food that a birthday party visitor typically consumes. This is how consumers' salivary glands become active and bacteria collect in their mouths, the scientists explain.
Samples from the wrong cake were transferred to bacteria-friendly agar plates
Next, they asked the subjects to blow out the candles on the wrong cake. The researchers then collected the samples on the film and placed them on bacteria-friendly agar plates. This experiment was repeated a total of three times on separate days by eleven subjects.
Effects of blowing out the candles on exposure to bacteria
On average, blowing out the candles increased the level of bacteria on the cake by 15 times, the doctors say. In some subjects, however, the exposure was much higher. The explanation for this is simple: some people simply produce more saliva, known as so-called hypersalivation, the scientists explain further. Blowing out the candles by a test subject even increased the bacteria by a factor of 120. Some people blow out the candles and do not transmit bacteria to the cake. But there are also people who transmit a lot of bacteria for some reason, explains author Professor Paul Dawson.
Bacteria are a normal part of our lives
The results of the current study certainly sound very unsavory at first. But you shouldn't worry too much about blowing out the candles at birthday parties and exposure to bacteria. Bacteria are a normal part of our everyday life, the authors explain. Of course, some potentially harmful germs may be present in the blow end's saliva, such as Streptococcus pneumonia and Staphylococcus aureus. However, these amounts are not sufficient to harm the cake's consumers, the researchers say. After all, people have blown out the candles from their cakes for centuries and death from a contaminated cake is unlikely to have happened, the scientists add.
The risk to our health is very low
There is no great health risk from the old tradition. Even if you've eaten such a cake 100,000 times, the chances of getting sick would be very minimal, adds Professor Dawson. In other words, consuming a cake with an increased bacterial load will not be fatal, but if you've ever been looking for an excuse not to eat the birthday cake, the argument with the bacteria is certainly pretty convincing. (as)