why fast food hamburgers don't rot

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why fast food hamburgers don't rot

Postby jennypeng » Thu Nov 04, 2010 10:42 am

I'm curious about the recent report of McDonald's hamburger not decomposing and am thinking of doing my school science project about that. But I'm not sure how I can turn that into a scientific experiment. One idea is observing how McDonald's hamburger changes compared to other fast food burgers eg. Burger King, Wendy's etc. I think that would be interesting but have too many variables that are outside control?
Another idea is to test what ingredient in that hamburger that slows down rotting process i.e. salt. I can then test that by making homemade hamburgers with different levels of salt and observe how they change. My questions are:

would this be a legitimate scientific experiment. do you think salt will affect rate of the burgers rotting?
apart from obvious signs of the hamburger rotting, how can I measure the level of bacteria in each hamburger to determine which is rotting faster?
how can I keep the burgers for observation to control environmental variables.
is this experiment too complicated for a 7th grade project. If so, how can I simplify it?

Thank you very much for your help.
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Project Question: I'm interested in experimenting whether MacDonald's hamburger really does not decompose and how does it compare to other fastfood hamburgers. I would like to find out what affects food to decompose and what environment I should set up the experiment
Project Due Date: Dec 5
Project Status: I am just starting

Re: why fast food hamburgers don't rot

Postby sciencediplomat » Fri Nov 05, 2010 7:32 pm

Hi Jenny
this sounds like a cool experiment and one that Im sure everyone would find interesting.I actually had a classmate conduct the first topic you mentioned several years ago and it was very succesful.Both of your proposed topics are plausible.The second topic you proposed was actually conducted and here is an article about it:http://www.theglobeandmail.com/life/the-hot-button/the-mcdonalds-burger-wont-destruct-heres-why/article1787309/
I would infer that salt would be one of the main reasons that the hamburger would preserve however this is your hypothesis so you don't have to worry about guessing correctly.The whole purpose of an experiment is to learn and enjoy it!You could measure the bacteria by purchasing or borrowing(if you know a teacher that has one)a bacterial culture kit.You could create the enviromental conditions and manipulate them.i.e by putting them in a certain location and making sure that they are exposed to certain conditions that moisture is the same,etc.
It would be an intriguing experiment and you could even compare your results to the already-conducted experiment.
This is an outline of the other experiment:p://aht.seriouseats.com/archives/2010/11/the-burger-lab-revisiting-the-myth-of-the-12-year-old-burger-testing-results.html

If you have any more questions post away! :D
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Re: why fast food hamburgers don't rot

Postby jennypeng » Sun Nov 07, 2010 9:38 pm

Hi
Thank you for your help. The links you recommended were very helpful and I think I can be more specific in how to conduct the experiment.
:)
jennypeng
 
Posts: 5
Joined: Mon Nov 01, 2010 6:58 am
Occupation: Student 7th grade
Project Question: I'm interested in experimenting whether MacDonald's hamburger really does not decompose and how does it compare to other fastfood hamburgers. I would like to find out what affects food to decompose and what environment I should set up the experiment
Project Due Date: Dec 5
Project Status: I am just starting

Re: why fast food hamburgers don't rot

Postby jennypeng » Sat Dec 04, 2010 1:20 am

Hi
I have finished first phase of my experiment. I put a McDonald hamburger on a plate and another in a ziplock bag. I've logged the changes in the burgers for the past two weeks. As I predicted, the one in the ziplock bag has lots of mold and fungus growing in it. My teacher suggests that I measure the bacteria from the burgers using algae petri dishes and do a more scientific count of the bacteria that has grown. Can you help to explain how do I transfer the mold growing on the burger to the petri dish? Can I just use a clean cotton swab to swab the burger then on to the dish? Also should I do this wearing masks and gloves to avoid
inhaling anything dangerous that can be airborne when I take the moldy burger out of the bag? Finally, how do I count the bacteria on the dish?

Thanks.
jennypeng
 
Posts: 5
Joined: Mon Nov 01, 2010 6:58 am
Occupation: Student 7th grade
Project Question: I'm interested in experimenting whether MacDonald's hamburger really does not decompose and how does it compare to other fastfood hamburgers. I would like to find out what affects food to decompose and what environment I should set up the experiment
Project Due Date: Dec 5
Project Status: I am just starting

Re: why fast food hamburgers don't rot

Postby staryl13 » Sat Dec 04, 2010 4:47 pm

Hi!
Using a cotton swab would definitely work, and please do take all safety precautions such as masks and gloves while handling any of these microbes. The best way to count the bacteria in a dish can be found in this article:

http://www.ehow.com/how_5008505_count-b ... -dish.html

Hope this helps!
"There is a single light of science, and to brighten it anywhere is to brighten it everywhere." -Isaac Asimov
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Re: why fast food hamburgers don't rot

Postby jennypeng » Thu Dec 09, 2010 5:19 pm

I did a swab on the petri dishes (with algae nutrient) with mold that grew on my hamburgers 2 days ago - but I am not seeing any visible signs of bacteria growing. How long does it take for them to grow? Should I worry that my procedure has gone wrong? I kept the petri dishes in my garage where temperature is around low 60s. Is that too cold? I've since brought them into the house for more natural daylight and warmer temperature. Please help. My project is due in two days!!!
jennypeng
 
Posts: 5
Joined: Mon Nov 01, 2010 6:58 am
Occupation: Student 7th grade
Project Question: I'm interested in experimenting whether MacDonald's hamburger really does not decompose and how does it compare to other fastfood hamburgers. I would like to find out what affects food to decompose and what environment I should set up the experiment
Project Due Date: Dec 5
Project Status: I am just starting

Re: why fast food hamburgers don't rot

Postby nithintumma » Thu Dec 09, 2010 7:33 pm

Generally when you grow bacteria, you place the bacteria in an incubator with a fixed level of CO2 and a temperature of about 37 degrees Celcius (98.6 degrees Fareighheit), which is significantly warmer than your garage. In addition bacteria grow best in a humid environment.

However, from what I understand you transferred the mold from the hamburgers to agar plates. Mold is not bacteria, so it might not be able to grow on the petri dishes that you are using. If you have time, I would suggest looking into trying a commercial agar plate; most mold grows well on agar.If you cannot purchase agar plates, here is a link to creating your own agar plates out of petri dishes. http://www.ehow.com/how_5537293_grow-mold-petri-dish.html

In addition, mold grows best in humid, warm conditions.

Because mold does not grow in individual colonies on agar plates like bacteria, it might be difficult to quantify the amount of mold that you see on the agar plate, I would suggest looking at the density or the size of the mold growth.

Hope this helps, and Good Luck with your project!

Nithin T
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Re: why fast food hamburgers don't rot

Postby jennypeng » Thu Dec 09, 2010 9:45 pm

My petri dishes were ordered for me by my teacher. They already contain agar nutrient. Shouldn't that help bacteria to grow? When I did the swab, I did not wet the end of the cotton bud. Maybe that affected how much mold I actually collected? They petri dishes have been moved to a warmer room but should I also put them somewhere dark?
jennypeng
 
Posts: 5
Joined: Mon Nov 01, 2010 6:58 am
Occupation: Student 7th grade
Project Question: I'm interested in experimenting whether MacDonald's hamburger really does not decompose and how does it compare to other fastfood hamburgers. I would like to find out what affects food to decompose and what environment I should set up the experiment
Project Due Date: Dec 5
Project Status: I am just starting

Re: why fast food hamburgers don't rot

Postby burgy » Wed Feb 09, 2011 12:06 am

jennypeng wrote:I'm curious about the recent report of McDonald's hamburger not decomposing and am thinking of doing my school science project about that. But I'm not sure how I can turn that into a scientific experiment. One idea is observing how McDonald's hamburger changes compared to other fast food burgers eg. Burger King, Wendy's etc. I think that would be interesting but have too many variables that are outside control?
Another idea is to test what ingredient in that hamburger that slows down rotting process i.e. salt. I can then test that by making homemade hamburgers with different levels of salt and observe how they change. My questions are:

would this be a legitimate scientific experiment. do you think salt will affect rate of the burgers rotting?
apart from obvious signs of the hamburger rotting, how can I measure the level of bacteria in each hamburger to determine which is rotting faster?
how can I keep the burgers for observation to control environmental variables.
is this experiment too complicated for a 7th grade project. If so, how can I simplify it?

Thank you very much for your help.



This experiment is really complicated for a 7th grade like you but you deserve an applause especially if you finish this one. Preservatives also help make hamburger stays longer. Some scientist claims that hamburger manages to stay unspoiled because of some reasons. One of this is because it is fatty, and of course salty. Sad but true it also has no nutrients. Better avoid it i guess.
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Re: why fast food hamburgers don't rot

Postby staryl13 » Wed Feb 09, 2011 9:37 am

Hi,
Wetting or not wetting the cotton swab should not make a difference for your experiment. You may just need a couple more days for the mold to multiply, but moving to a warmer place might create a better environment to enhance the mold growth. The agar plates you have should be fine because the agar will have enough nutrients for the mold to grow. Just keep in mind not to confuse bacteria and mold because mold is a fungus, which is fundamentally different from bacteria! Hope this helps, good luck!
"There is a single light of science, and to brighten it anywhere is to brighten it everywhere." -Isaac Asimov
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