Materials:

4 eggs

two cups of milk (preferably whole/full cream, or made from powdered milk)

your own hair from a hairbrush or comb

small saucepan

mixing bowl

baking tray or cookie sheet

aluminum foil

candy thermometer or cooking/meat thermometer

stove/oven (with oven mitts/pot holders)

part a: eggs

crack your eggs over your mixing bowl one at a time. separate the egg whites and yolks so that only egg whites are in your mixing bowl. if you get any egg yolk into your egg white mixture, you will need to restart.

pour the raw egg whites into a small saucepan and place over “low heat” on your stove.

place your thermometer into the mixture and begin recording the temperature of the egg whites.

make observations about the egg white mixture as the temperature increases. you might want to mention the appearance, color, texture, or smell of the mixture. record all observations and their associated temperatures in your data table.

keep heating the mixture until a clear texture change in the entire mixture occurs. you may need to increase the heat of the stovetop if the mixture’s temperature isn’t increasing.

dispose of the egg whites. clean the saucepan, mixing bowl, and thermometer

part b: milk

pour two cups of milk into your clean saucepan. if you are using powdered milk, first combine the powdered milk with about two cups of water, mix well, and let sit before adding to saucepan.

turn the stove on to low heat and insert your thermometer to begin recording temperature.

make observations about the milk as the temperature increases. try to mention the appearance, color, texture, or smell of the mixture. record all observations and their associated temperatures in your data table.

keep heating the mixture until there is a clear texture change. you may need to increase the heat of the stove top if the temperature isn’t increasing.

dispose of the milk. clean the saucepan, bowl, and thermometer



part c: hair

preheat your oven to 200 degrees fahrenheit.

place aluminum foil over your baking/cookie sheet.

acquire some of your own hair from a comb or toothbrush and place it on your covered baking/cookie sheet. insert the sheet into the oven once it has reach 200 degrees fahrenheit.

let the hair heat up in the oven, watching for any changes (about 5 minutes).

increase the temperature of the oven by 25 degrees fahrenheit and allow the hair to heat up for 5 minutes. record any changes to the hair appearance or texture. you can simply observe the hair through the oven window, but you may want to remove the hair from the oven for a closer look. make sure to use oven mitts and to not open the oven too often (one observation per temperature increase will be enough).

record all observations and their associated temperatures in your data table. keep heating the hair until there is a noticeable change in appearance or texture.

remove the hair from the oven and turn it off. allow the hair to cool and then dispose of the hair and aluminum foil.

questions:

about at which temperature did the protein in eggs denature? how could you tell?

about at which temperature did the protein in milk denature? how could you tell?

about at which temperature did the protein in hair denature? how could you tell?

why do you think different proteins denature at different temperatures?

why might it be useful to denature a protein?

                                         Protein Denaturation

NAME OF MAIN PROTEIN:     TEMPERATURE:      OBSERVATION:

EGGS: - 144°F - Then four eggs were cracked into a bowl and separate the yolk from the egg whites. Then was poured the raw egg whites into a saucepan and turn the stove on low heat, then placed the thermometer. The temperature of the egg whites began to increase 80°F. The texture began to become tough and rubber like. The temperature began to increase again to 160°F.

MILK: - 180°F - Two cups of milk was then poured the into a clean saucepan, then was turned it on low heat and inserted the thermometer into the saucepan. The temperature of the milk began to increase to 80°F. The color stayed the same and the texture began to thicken.

HAIR: - 225°F - The oven was then preheated to 200°F, then put aluminum foil over your baking sheet. Hair was revieved from a hair brush and placed was on the baking sheet, then put the baking sheet in the oven. The hair heated for 5 minutes then increased the oven to 225°F, then it heated for another 5 minutes. The texture of the the hair became stiffer and dry.  

Questions:

1.What is the most abundant type of protein in egg white? What do you think its purpose is?

2.What is the most abundant type of protein in milk? What do you think its purpose is?

3.What is the most abundant type of protein in human hair? What do you think its purpose is?

4.What happens when a protein denatures?

5.What conditions might cause a protein to denature (list at least two)?

Answers:

1.  The most abundant type of protein in egg white is ovalbumin is the most abundant protein in albumen.

2.  The most abundant type of protein in milk is caseins.

3.  The most abundant type of protein in human hair is  biomaterial primarily composed of protein, especially alpha-keratin.

4.  Denaturation of proteins involves the destruction of the tertiary and secondary structure.

5.  Conditions that might cause a protein to denature is the heat increases the knortic energy which causes the molecules to vibrate so rapidly and violently that the bonds are disrupted, and the heat can disrupt hydrogen bonds and non-polar hydrophobic interaction.

Question:

1.About at which temperature did the protein in eggs denature? How could you tell?

2.About at which temperature did the protein in milk denature? How could you tell?  

3.About at which temperature did the protein in hair denature? How could you tell?

4.Why do you think different proteins denature at different temperatures?

5.Why might it be useful to protein?

1.After a few minutes, the temperature of the eggs increased to 80°F, then five minutes later it increased agin to 160°F. The eggs then began to become tough and rubbery.

2.After a few minutes, the temperature of the boiling milk increased to 80°F. It then became a thick consitantsy.

3.After the hair was in the oven set at 200°F, the hair became stiff like, then was bumped up to 225°F. It then became stiffer and dry.

4.Yes, different proteins denature at different temperatures can melt above 106°F.

5.Denature a proteins change their structure in the presence of certain chemicals, acids or bases.

In this assignment, data was collected throughout the experiments. During the egg white experiment, the temperature rose of the egg whites began to increase 80°F, then increase again to 160°F, texture began to become tough and rubber like. During the milk experiment, temperature of the milk began to increase to 80°F, the color stayed the same and the texture began to thicken. During the hair experiment, the hair heated for 5 minutes in the 200, the oven was increased to 225°F. Then heated for another 5 minutes, then the texture of the the hair became stiffer and dry.  

Material:

⦁4 eggs

⦁Two cups of milk  

⦁Your own hair from a hairbrush

⦁Small saucepan

⦁Mixing bowl

⦁Baking tray  

⦁Aluminum foil

⦁Candy Thermometer  

⦁Stove and Oven