Of Mushrooms, Molds, and McDonald's: Butter and the Not Butters

When I set up my Mushrooms, Molds, and McDonald's experiment last October, I set up three treatments (water, no water but covered, and open to the air) for butter, margarine, and Smart Balance "healthy" spread. Here are the pictures and jar numbers.

I threw out the fries and burgers a couple of months after setting up the experiment because we'd clearly learned that the amount of microbial growth is influenced by the water activity of the food. But the fats never really grew mold, and my husband was anxious to get them out of our sunroom in time for our Thanksgiving party. Can you blame him? I stuck all the jars in our mudroom and pretty much forgot about them until a few months ago. Overall the project is pretty disgusting. All the fats in these jars smell like plastic because they are pretty rancid.

I've been meaning to post an update on this project, but with 5 biology classes to teach, the semester has been very busy and I have far more important priorities than whether mold grows on fats.

Well, here we are, six months later (ewww!). We have mold in some of the jars and it's been there for awhile now, and an update is very overdue. Here's what we have. Hang onto your seats. This is going to be exciting.

Groundbreaking McMold results: Do molds grow on industrial fats?

Jars 10-12 (margarine): a very slight bit of mold in the jar with added water (jar 10). No mold in jars 11 or 12.

Jars 13-15 (butter): Mold in jar 13 (jar with added water). No mold in jars 14 or 15.

Jars 22-24 (Smart Balance): Again, mold in jar 22 ( the jar with added water). No mold in jars 23 or 24.

Well, that's it, folks. Fungi are capable of breaking down pretty much any carbon source as long as they have some water. Surprise.

Take home messages:

1) Even after 6 months, there's no mold growing on any of the fats in the jars that were dry. The rumor with pictures from the 1980s, spread around by the Weston A Price Foundation folks, that butter will get used by wild animals while industrial fats won't probably needs to be replicated and documented scientifically. My husband feeds chipmunks Sugar Frosted Flakes and they eat those over wild foods. That doesn't make Sugar Frosted Flakes healthy.

2) While Smart Balance and margarine are pretty gross, whether or not we eat something probably shouldn't be dictated by whether it will be eaten by wildlife or broken down by microorganisms. I wouldn't eat compact discs or rocket fuel, either.

If anyone would like to see some pictures of the molds growing on these fats, I'd be happy to take pictures later in the week when I have time. You'll be able to verify that these are the original jars by comparison to the pictures of the jars in the link above, which are all a little different in shape and size. Just leave a message in the comments field if you're interested.