Home Store Project Ideas Project Guide Ask An Expert Blog Careers Teachers Parents Students

The Curdling Properties of Different Milks: How to Avoid Little Miss Muffet's Curds *

Difficulty
Time Required Average (6-10 days)
Prerequisites None
Material Availability Readily available
Cost Very Low (under $20)
Safety Adult supervision is recommended when using the stove.
*Note: This is an abbreviated Project Idea, without notes to start your background research, a specific list of materials, or a procedure for how to do the experiment. You can identify abbreviated Project Ideas by the asterisk at the end of the title. If you want a Project Idea with full instructions, please pick one without an asterisk.

Abstract

Has a milk-based soup, sauce, or gravy ever curdled on you (formed lumps) as you were preparing it? Curdling is the process of coagulation that occurs where the proteins in the milk clump together. Sometimes curdling is desirable—for example, if you want to make a delicious cheese or yogurt—but if you are trying to make a milk-based soup or gratin, or if you're adding milk to a hot drink, curdling is very unwanted because you lose the smooth, creamy texture. Nobody likes clumps and lumps in their hot chocolate, unless they're marshmallows!

What influences the curdling of milk proteins? The primary factors are acids, such as those found in juices and vegetables; tannins, such as those found in potatoes, coffee, or tea; and bacteria, which are sometimes deliberately added (if you are making cheese or yogurt), but may also develop if the milk is no longer fresh and starts to sour. As the bacteria grow and multiply, they produce lactic acid, which causes the milk proteins to clump together.

In this cooking and food science fair project, you will investigate cow milks that have different percentages of milk fat, and discover which ones are less prone to curdling, and are therefore more desirable for milk-based soups, gravies, and gratins. You will first need to read about the structure of milk: the milk proteins (the caseins and the whey), the micelles, the calcium phosphate, and the fat globules. You will then test and compare the curdling properties of cow milks that have different percentages of milk fat, from skim milk on up to cream. For each trial, choose one type of milk and slowly warm and whisk it in a saucepan until it comes to a simmer. Add a small amount of an acid, such as lemon juice or vinegar, and then remove the milk from the heat. Allow the milk to cool and then strain it. Measure the contents of the strainer (the curds) by weight or by volume. Be sure your milks are very fresh, use the same amount of milk for each trial, and cook each of the milks in the same fashion. As you compare your curd measurements, think about the relative protein content of each type of milk. Be sure to record all your data, amounts, and settings for your trials in your lab notebook.

When you finish this science fair project, you will be a milk-cooking master, and know how to avoid those dreadful lumps!

Cite This Page

MLA Style

Science Buddies Staff. "The Curdling Properties of Different Milks: How to Avoid Little Miss Muffet's Curds" Science Buddies. Science Buddies, 7 Dec. 2012. Web. 29 Aug. 2014 <http://www.sciencebuddies.org/science-fair-projects/project_ideas/FoodSci_p029.shtml>

APA Style

Science Buddies Staff. (2012, December 7). The Curdling Properties of Different Milks: How to Avoid Little Miss Muffet's Curds. Retrieved August 29, 2014 from http://www.sciencebuddies.org/science-fair-projects/project_ideas/FoodSci_p029.shtml

Share your story with Science Buddies!

I did this project I Did This Project! Please log in and let us know how things went.


Last edit date: 2012-12-07

Variations

  • At what pH do different cow milks curdle? In this variation, you will choose cow milks that have varying degrees of milk fat, and add different amounts of an acid to determine the acidity at which each of the milks first curdles. You will need a way to measure the acidity of the milk-acid mixture, and you will need to keep the temperature of the milks constant for each trial. Hint: Bring a large saucepan of milk up to a certain temperature, and then add equal amounts of the warmed milk to small bowls with differing amounts of an acid inside.
  • Mammal milks contain different ratios of proteins, fat, and carbohydrates, depending on the needs of the infant mammal. Compare the curdling properties of different mammal milks, such as cow, goat, sheep, and buffalo. Do your results make sense when you think about the different amounts of protein that each contains?

Share your story with Science Buddies!

I did this project I Did This Project! Please log in and let us know how things went.

Ask an Expert

The Ask an Expert Forum is intended to be a place where students can go to find answers to science questions that they have been unable to find using other resources. If you have specific questions about your science fair project or science fair, our team of volunteer scientists can help. Our Experts won't do the work for you, but they will make suggestions, offer guidance, and help you troubleshoot.

Ask an Expert

Related Links

If you like this project, you might enjoy exploring these related careers:

Scientists inspecting special corn oil

Food Scientist or Technologist

There is a fraction of the world's population that doesn't have enough to eat or doesn't have access to food that is nutritionally rich. Food scientists or technologists work to find new sources of food that have the right nutrition levels and that are safe for human consumption. In fact, our nation's food supply depends on food scientists and technologists that test and develop foods that meet and exceed government food safety standards. If you are interested in combining biology, chemistry, and the knowledge that you are helping people, then a career as a food scientist or technologist could be a great choice for you! Read more
scientist performing experiments

Biochemist

Growing, aging, digesting—all of these are examples of chemical processes performed by living organisms. Biochemists study how these types of chemical actions happen in cells and tissues, and monitor what effects new substances, like food additives and medicines, have on living organisms. Read more
food science technician checking an egg

Food Science Technician

Good taste, texture, quality, and safety are all very important in the food industry. Food science technicians test and catalog the physical and chemical properties of food to help ensure these aspects. Read more

Looking for more science fun?

Try one of our science activities for quick, anytime science explorations. The perfect thing to liven up a rainy day, school vacation, or moment of boredom.

Find an Activity