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Spoiled Milk

Madison White Science Fair Project

Madison White

on 23 February 2013

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Transcript of Spoiled Milk

Purpose The purpose of my experiment is to determine how long it takes for whole milk, 2% milk, and skim milk to spoil when it is left at room temperature. There are three specific questions that I would like to answer during this experiment. They are:
1. How long does it take for whole milk to spoil?
2. How long does it take for 2% milk to spoil?
3. How long does it take for skim milk to spoil?
I also think that other people will benefit from this experiment. It will help them to know how long each kind of milk can be left at room temperature before it begins to spoil.
Hypothesis I believe that the milk with the highest fat content, the whole milk, will be the first one to spoil at room temperature. Based on my research, harmful bacteria that leads to spoilage begins to grow when milk reaches higher than 45 degrees. Room temperature is greater than this, so spoilage will begin with all three kinds of milk once it is left unrefrigerated. It is my belief that the more fat the milk contains, the quicker it will go bad. Experimental Design As with any experiment, there are different variable associated with this one. The temperature of the room and the amount of each kind of milk that is used remains constant. The fat content of the milk is the variable that is manipulated. The type of cup that the milk is in is the independent variable in this experiment. Materials In order to complete this experiment, several different materials are needed. The following is a list of supplies that you will need when you start:
1 cup of whole milk
1 cup of 2% milk
1 cup of skim milk
3 cups
measuring cup
clock or timer
paper Procedure To begin the project, you need to label three different cups for each type of milk (whole, 2%, and skim). Measure one cup of each kind of milk and pour it into the correctly labeled Styrofoam cup. Write down the time you began the experiment. You will then need to leave the cups of milk sitting out at room temperature. Be sure to check them often. Document the time that each milk clearly begins to spoil. Results Conclusions At the end of the experiment, the skim milk was the first to spoil, followed by the 2% milk and then the whole milk. Based upon the results of the experiment, it was the milk with the lowest fat content that spoiled the fastest. The purpose of my experiment was to find out which type of milk spoiled the fastest and this experiment led me to those results. The major result that came from this experiment is that the lower the fat content of the milk, the quicker it will spoil when left sitting out at room temperature. At the end of the experiment, I found that the results were the opposite of my hypothesis, as I had guessed that the milk with the higher fat content would spoil first. I can now guess that the higher fat content of the milk allows it to stay consumable for a longer period of time. It would now be possible to take this experiment further and see if it makes a difference what brand of milk you use or to find out exactly what temperature each kind of milk will spoil at. By: Madison White Background Research There are two main sources of bacteria found in milk. They are lactic acid and coliforms. When milk spoils, it undergoes physical and chemical changes. (Spoiled) The expiration date shown on the foods we buy and eat are not always set in stone. You can usually see or smell when something is spoiled before finding out by tasting it. (PC) Temperature is the most important factor when it comes to whether or not milk spoils. When milk is allowed to get above 45 degrees, harmful bacteria can begin to grow fast. (Rushing) Louis Pasteur developed pasteurization in the mid-1800s. Michigan became the first state to ban the sale of unpasteurized milk in 1948. (Pike) Buttermilk can be safely stored for 3-5 days. Evaporated milk that has been opened can be safely stored for 4-5 days. (Fisher) Bibliography Fisher, Lesley and Lydia Medeiros. Family and Consumer Sciences. The Ohio State University, 2010. Web. 18 Nov 2012.<http://ohioline.osu.edu/hyg-fact/5000/pdf/5403.pdf>

PC, Sofia. "Does Milk Spoil At the Same Rate As 2% Skim Milk?" Education.com. n.p, n.d. Web. 16 Nov 2012. <http://www.education.com/science-fair/article/does-whole-milk-spoil-same-rate-as-skim/>

Pike, William E. "Raw Milk and the Sour State." The Freeman. n.p., n.d. Web. 17 Nov 2012.<http://www.fee.org/the_freeman/detail/raw-milk-and-the-sour-state/>

Rushing, J.E. Department of Food Science. NC State University, n.d. Web. 17 Nov 2012. <http://www.ces.ncsu.edu/depts/foodsci/ext/pubs/milksafety.html>

"Spoiled Milk: How do different temperatures of liquid affect its rate of spoilage?" Gale Schools. n.p., n.d. Web. 16 Nov 2012. <www.galeschools.com/sci_try/spoiled_milk.htm> Data Analysis Spoiled Milk How long does it take for milk to spoil?
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