Science Buddies: "Ask an Expert"

i've conducted an experiment so far in which i've grown bread mold

does food coloring change the color of mold?
i put one drop of red, green, and blue food coloring on different slices > added water and dust > waited for a week > and grew lots of mold

so far, all the mold colors seem consistent. it is whitish but some of the color is still showing. it's hard to tell whether or not it's the mold itself or just the color seeping through.

i've looked but is there any information out there that anyone can find about food coloring changing the color of bread mold? or mold in general?


also, i ran another trial in which i added salt to a plain piece of bread and added water and dust. i noticed that mold growth was significantly slower than that without salt.


so in all, i'm testing two different variables in different trials.
1: does food coloring change the color of bread mold?
2: does salt slow the rate of bread mold growth?


i feel as though if i can't get enough information on food coloring affecting mold, then i'll just completely eliminate it from my project and just focus on salt and the rate of mold growth instead.

Hi.

Molds are white when they start to grow, and will develop color when the spores form. The color of the spores is characteristic of the species, and is usually blue, black, green, or gray. Food coloring molecules are small water soluble molecules in solution that will interact with other molecules, but would not necessarily bind specifically to the mold. The food coloring probably added moisture that was essential to the growth of the mold, but probably did not affect the basic color of the mold. If the vegetative phase of growth was white, then there was probably no effect.

However, you can report these results because you did the experiment and observed the outcome. In a scientific experiment, a negative result should be reported even if it doesn't match your original hypothesis. Hopefully, the outcome will help you decide what do to for your next experiment.

Salt, or NaCl, however is a molecule that is important to the growth of microorganisms, including molds. All microorganisms have an NaCl concentration that is optimum for growth, and will not grow as well in lower or higher concentrations. Here is a reference that compared growth of 5 different molds in different concentrations of salt.

http://www.pubmedcentral.nih.gov/picren ... obtype=pdf

Notice the graph on page 3764. It shows the number of fungal (mold) cells vs concentration of NaCl.

What concentrations of NaCl did you use? You should have seen a difference in the time it took for the mold colonies to appear. I think you are saying that growth was slower in the bread sample with salt, and if that is the case, you used a concentration that was higher than optimum. This is a significant result and you should definitely report it. What are the implications of a NaCl concentration that is not optimum for mold growth? Can you think of any practical applications?

Let us know if you have any other questions.

Donna Hardy

why thank you!
yes, the vegetative phase of growth was most certainly white.
i'll be sure to report my findings regardless of the outcome not having supported my hypothesis.

for the salt trial i used a high concentration of salt. i figured this has to be well above the optimum for mold growth therefore making the rate of growth much, much slower.

practical application? one being salt can obviously preserve bread longer.. but who would really want salty bread?
any suggestions?