MadSci Network: Microbiology

Re: How should I measure mold???

Date: Tue Feb 22 09:17:17 2000
Posted By: Don Schaffner, Faculty, Food Science, Rutgers University
Area of science: Microbiology
ID: 950986617.Mi

> I have to restart  my project because my method of measuring the mold 
> was inaccurate: I measured the area in square centimeters, with a ruler. 
This sounds reasonable to me. Who decided that this was too inacurate?

Keep in mind that there are many sources of variability n your experiment to start with (i.e. differents species on different breads, etc.) so a little bit of measurement variability may not really be all that significant in drawing your conclusions.

Also keep in mind that some molds are toxic, so try to keep the bread wrapped up, and then discard at the end of the experiment without opening.

> I was wondering if you knew a more accurate way of measuring the mold, 
> because it does not grow in a symmetrical or square shape. 
You could overlay some tracing paper on the mold, trace the shape, and then overlay the tracing paper on some graph paper, and count the squares.

Be careful not to disturb the mold, and spread the spores around because this will bias your results, by increasing the apparent growth.

> Is it possible to measure the mold in depth, too?
Yes, but it's tricky, and with little additional benefit to your project. Molds are aerobic. That means they need oxygen, so they will grow mostly on the surface of bread, anyway.

Another option would be to make a point estimate... just count the number of days until any mold is visible to the naked eye.

I still like your measuring idea better. Are you making measurements every few days? If you are, you can plot the increase in area vs. time for the different breads.

Be sure to also keep in mind that two breads may have different species of mold, which grow at different rates.. so the difference may not be due to the bread, but the mold that happened to be present at the start of the experiment.

This is a great project idea! Keep up the good work, and let me know if you have more questions.

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