Milk Glue
Objective: Applying our knowledge of protein denaturing, we will make “casein” glue by curdling the milk with an acid.
Materials: Skim Milk, Vinegar (5-7% Acetic acid), 400 mL glass beaker or pan for heating, Sodium Bicarbonate (baking soda
(base)), Ziploc bag for glue, cheesecloth, food coloring
Background:
There are various ways that proteins can be denatured including temperature, pH, metal ions and acids. In the process
of making cheese, a microorganism is used that lowers the pH, which in turn causes the milk to curd. An enzyme called RENNET
then causes the curds to coagulate or clump together. Next time you eat cheese or custard, look on the package for the word
“RUNNET”. Naturally when milk sours forming curds, it is due to the action of bacteria found in the milk.
Milk is about 3% Casein. Casein is a protein made of carbon, hydrogen, oxygen, Nitrogen, Sulfur and Phosphorus.
Besides food products, Casein can be used in a variety of non-food products, such as combs, buttons, glue, paints, plastics and
many more.
Pre-Lab Questions:
1.
2.
3.
4.
5.
What types of proteins are found in Milk?
Why is milk a homogeneous mixture (a solution) and not a compound. Justify your answer
Is milk an acid or a base?
What is the purpose of adding vinegar (acetic acid) to the milk?
Could other acids (hydrochloric, HCl or nitric, HNO3) be used to separate the protein from the solution?
Procedure:
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
12.
13.
Place 250 mL of skim milk in the beaker
Add 40 mL of Vinegar to the beaker
Heat slowly and stir continuously
When the mixture begins to curdle, remove from the heat and continue stirring until the curdling stops
Allow curds to settle to the bottom;
a. The top liquid is called WHEY.
Place the cheese cloth over the top of the beaker and drain off the whey
Place the curds in the cheesecloth and squeeze out as much water as possible
Move the curds to your plastic mixing dish
Add 10 mL of water (you can add more if needed later)
Add 30 g of Sodium Bicarbonate
a. You will see bubbles; It is a Carbon Dioxide releasing reaction between the remaining vinegar and the
sodium bicarbonate
Stir with your spoon until you have a glue like consistency
You may add a small amount of food coloring if you wish
Test your glue by pasting two pieces of paper together
Post-Lab Questions:
6. The curds in sour milk consist of what major protein?
7. How is cheese making different from milk souring?
8. List some other foods that contain proteins that may be used in other non-food products.
Milk Glue
Objective: Applying our knowledge of protein denaturing, we will make “casein” glue by curdling the milk with an acid.
Materials: Skim Milk, Vinegar (5-7% Acetic acid), 400 mL glass beaker or pan for heating, Sodium Bicarbonate (baking soda
(base)), Ziploc bag for glue, cheesecloth, food coloring
Background:
There are various ways that proteins can be denatured including temperature, pH, metal ions and acids. In the process
of making cheese, a microorganism is used that lowers the pH, which in turn causes the milk to curd. An enzyme called RENNET
then causes the curds to coagulate or clump together. Next time you eat cheese or custard, look on the package for the word
“RUNNET”. Naturally when milk sours forming curds, it is due to the action of bacteria found in the milk.
Milk is about 3% Casein. Casein is a protein made of carbon, hydrogen, oxygen, Nitrogen, Sulfur and Phosphorus.
Besides food products, Casein can be used in a variety of non-food products, such as combs, buttons, glue, paints, plastics and
many more.
Pre-Lab Questions:
1.
2.
3.
4.
5.
What types of proteins are found in Milk?
Why is milk a homogeneous mixture (a solution) and not a compound. Justify your answer
Is milk an acid or a base?
What is the purpose of adding vinegar (acetic acid) to the milk?
Could other acids (hydrochloric, HCl or nitric, HNO3) be used to separate the protein from the solution?
Procedure:
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
12.
13.
Place 250 mL of skim milk in the beaker
Add 40 mL of Vinegar to the beaker
Heat slowly and stir continuously
When the mixture begins to curdle, remove from the heat and continue stirring until the curdling stops
Allow curds to settle to the bottom;
a. The top liquid is called WHEY.
Place the cheese cloth over the top of the beaker and drain off the whey
Place the curds in the cheesecloth and squeeze out as much water as possible
Move the curds to your plastic mixing dish
Add 10 mL of water (you can add more if needed later)
Add 30 g of Sodium Bicarbonate
a. You will see bubbles; It is a Carbon Dioxide releasing reaction between the remaining vinegar and the sodium
bicarbonate
Stir with your spoon until you have a glue like consistency
You may add a small amount of food coloring if you wish
Test your glue by pasting two pieces of paper together
Post-Lab Questions:
6. The curds in sour milk consist of what major protein?
7. How is cheese making different from milk souring?
8. List some other foods that contain proteins that may be used in other non-food products.
Milk Glue
Objective: Applying our knowledge of protein denaturing, we will make “casein” glue by curdling the milk with an acid.
Materials: Skim Milk, Vinegar (5-7% Acetic acid), 400 mL glass beaker or pan for heating, Sodium Bicarbonate (baking soda
(base)), Ziploc bag for glue, cheesecloth, food coloring
Background:
There are various ways that proteins can be denatured including temperature, pH, metal ions and acids. In the process
of making cheese, a microorganism is used that lowers the pH, which in turn causes the milk to curd. An enzyme called RENNET
then causes the curds to coagulate or clump together. Next time you eat cheese or custard, look on the package for the word
“RUNNET”. Naturally when milk sours forming curds, it is due to the action of bacteria found in the milk.
Milk is about 3% Casein. Casein is a protein made of carbon, hydrogen, oxygen, Nitrogen, Sulfur and Phosphorus.
Besides food products, Casein can be used in a variety of non-food products, such as combs, buttons, glue, paints, plastics and
many more.
Pre-Lab Questions:
1.
2.
3.
4.
5.
What types of proteins are found in Milk?
Why is milk a homogeneous mixture (a solution) and not a compound. Justify your answer
Is milk an acid or a base?
What is the purpose of adding vinegar (acetic acid) to the milk?
Could other acids (hydrochloric, HCl or nitric, HNO3) be used to separate the protein from the solution?
Procedure:
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
12.
13.
Place 250 mL of skim milk in the beaker
Add 40 mL of Vinegar to the beaker
Heat slowly and stir continuously
When the mixture begins to curdle, remove from the heat and continue stirring until the curdling stops
Allow curds to settle to the bottom;
a. The top liquid is called WHEY.
Place the cheese cloth over the top of the beaker and drain off the whey
Place the curds in the cheesecloth and squeeze out as much water as possible
Move the curds to your plastic mixing dish
Add 10 mL of water (you can add more if needed later)
Add 30 g of Sodium Bicarbonate
a. You will see bubbles; It is a Carbon Dioxide releasing reaction between the remaining vinegar and the sodium
bicarbonate
Stir with your spoon until you have a glue like consistency
You may add a small amount of food coloring if you wish
Test your glue by pasting two pieces of paper together
Post-Lab Questions:
6. The curds in sour milk consist of what major protein?
7. How is cheese making different from milk souring?
8. List some other foods that contain proteins that may be used in other non-food products.
Milk Glue
Objective: Applying our knowledge of protein denaturing, we will make “casein” glue by curdling the milk with an acid.
Materials: Skim Milk, Vinegar (5-7% Acetic acid), 400 mL glass beaker or pan for heating, Sodium Bicarbonate (baking soda
(base)), Ziploc bag for glue, cheesecloth, food coloring
Background:
There are various ways that proteins can be denatured including temperature, pH, metal ions and acids. In the process
of making cheese, a microorganism is used that lowers the pH, which in turn causes the milk to curd. An enzyme called RENNET
then causes the curds to coagulate or clump together. Next time you eat cheese or custard, look on the package for the word
“RUNNET”. Naturally when milk sours forming curds, it is due to the action of bacteria found in the milk.
Milk is about 3% Casein. Casein is a protein made of carbon, hydrogen, oxygen, Nitrogen, Sulfur and Phosphorus.
Besides food products, Casein can be used in a variety of non-food products, such as combs, buttons, glue, paints, plastics and
many more.
Pre-Lab Questions:
1.
2.
3.
4.
5.
Procedure:
What types of proteins are found in Milk?
Why is milk a homogeneous mixture (a solution) and not a compound. Justify your answer
Is milk an acid or a base?
What is the purpose of adding vinegar (acetic acid) to the milk?
Could other acids (hydrochloric, HCl or nitric, HNO3) be used to separate the protein from the solution?
1.
2.
3.
4.
5.
Place 250 mL of skim milk in the beaker
Add 40 mL of Vinegar to the beaker
Heat slowly and stir continuously
When the mixture begins to curdle, remove from the heat and continue stirring until the curdling stops
Allow curds to settle to the bottom;
a. The top liquid is called WHEY.
6. Place the cheese cloth over the top of the beaker and drain off the whey
7. Place the curds in the cheesecloth and squeeze out as much water as possible
8. Move the curds to your plastic mixing dish
9. Add 10 mL of water (you can add more if needed later)
10. Add 30 g of Sodium Bicarbonate
a. You will see bubbles; It is a Carbon Dioxide releasing reaction between the remaining vinegar and the sodium
bicarbonate
11. Stir with your spoon until you have a glue like consistency
12. You may add a small amount of food coloring if you wish
13. Test your glue by pasting two pieces of paper together
Post-Lab Questions:
6. The curds in sour milk consist of what major protein?
7. How is cheese making different from milk souring?
8. List some other foods that contain proteins that may be used in other non-food products.