I have revised my aim to a more precise one: "To determine the effect of host material and on the rate of macroscopic fungal growth in food". I've seen that I need to be accurate so I know exactly what it is I'm observing during my experiment. I'm doing some research right now.
I've decided it will be too complicated and inconvenient to include environment in the picture, because it'll mean my family will have to put up with petri dishes everywhere for weeks. It will just complicate things; I'm more interesting in which materials allow the most fungal growth. This will involve having multiple (probably 2) samples of each material, and put in the same place to eliminate environment as a variable. As well as this, I will be putting a set of samples in the refridgerator to compare the fungal growth (obviously, the fungal growth in the fridge will not be as fast because of the low temperature, so it will be a good comparison).
Equipment needed: petri dishes, mm ruler, magnifying glass, digital camera
I'm going to have to be really careful how I do this experiment, and I have to consider the following:
- Actual freshness of food, because I have to be certain that most of the materials I'm testing were produced at roughly the same time and have all deteriorated (as foods do) to approximately the same point
- How I measure the fungal growth; I'm thinking of measuring the "colony diameter" using a good old fashioned ruler, magnifying glass and camera =D i.e. placing a ruler on top of the petri dish to measure and give an accurate scale, magnifying glass on top of ruler to magnify, and photos taken of this setup for the sake of observation.
- With the slight alteration in experiment, I also have to revise my variables: Independent will be type of organic material; Dependent will be diameter/length of fungal growth (mm), and I will also attempt to calculate area (mm^2) if the shapes formed by the fungi are recognisable measurable; Controlled variables include environment (temperature, humidity, light, etc.), external contaminants (aside from fungi), size of test subjects, freshness of test subjects.
- Making sure results appear within the set time frame; this doesn't mean tampering with this experiment, this just means encouraging the mold growth by not fully closing the petri dish lids to allow air circulation, and possibly adding a couple of drops of water in the petri dish with the food samples, but not on or near them, to add moisture to the internal environments of the petri dishes. I have researched a bit, and seen that it generally takes a few days for fungi to grow, and I've decided that my previous estimate of 10 days should be right, which will mean repeating the experiment at least once, probably twice. If 10 days is not sufficient, which is highly unlikely, I can always extend the experiment until conclusive results can be seen.
Ooh there was something else I wanted to write, but I can't remember it right now. I'll post when I remember it... oohf my retirement is not looking good.
Friday, March 26, 2010
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