Objectives

By the end of this lab, students should be able to describe the process for making mayonnaise and explain the function of emulsifiers and how they work

Background

Some liquids cannot dissolve in each other. When combined they tend to separate. We call these liquids immiscible, for example oil and water. Being immiscible makes it difficult to prepare foods that contain both type of liquids without affecting quality and appearance. However, we can fix that problem by using an emulsifier to create an emulsion.  An emulsion is formed by first breaking up one of the liquids and dispersing it homogeneously into the other. This is generally done using a high-speed blender or homogenizer. After that, an emulsifier is added to prevent the liquids from separating. Mayonnaise is an example of an oil-in-water emulsion since oil is distributed in a continuous phase of water. Egg yolk is used as the emulsifier in mayonnaise since it contains lecithin; a compound that has the ability to bind both water and oil. It is able to do this because one end of the molecule is charged allowing it to interact with water while the other end is uncharged and non-polar like a fat, making it easy to interact with oil. This property is known as an amphiphilic property.

Materials and Equipment

  1. Stainless steel pot
  2. Stove
  3. Scale
  4. Thermometer
  5. Mixing spoon
  6. Mixing bowl
  7. Glass jars

Product Formulation

Ingredients Weight (g) Percentage (%)
Vegetable oil 430 86.7
Pasteurized egg 33 6.7
White vinegar 15 3
Lemon juice 10 2
Salt 6 1.2
Sugar 2 0.4
Total 496 100

Method  

  1. Pasteurize 2 large eggs in hot water (63oC) for 15 minutes. Note: Make sure to maintain this temperature since higher temperatures will cause coagulation of egg while lower temperatures could prevent adequate pasteurization required for food safety
  2. Separate pasteurized egg yolks from eggs and weigh out the required amount needed (33 g)
  3. Add lemon juice
  4. Add vinegar
  5. Mix vigorously until a homogenous liquid is achieved
  6. Gradually add vegetable oil with continuous and vigorous mixing. Note: This can be done by hand but can also be done by a high-speed mixer for greater speed and efficiency. The mayonnaise will thicken as you continue to mix. If it begins to thin to a watery consistency this is an indication that your emulsion has broken. If this happens you will have to start over. To avoid this, make sure to add the oil slowly.  
  7. Add salt, spice and sugar, and mix for another minute
  8. Bottle in sterilized jars
  9. Refrigerate

Lab Questions

  1. Why couldn’t egg white be used instead of egg yolk to create a mayonnaise emulsion? (2 points)
  2. Differentiate between the terms miscible and immiscible (2 points)
  3. Give an example of an oil-in-water emulsion other than mayonnaise (1 point)
  4. Name an emulsifier other than lecithin or egg yolk that is used in the food industry (2 points)
  5. Taste the mayonnaise. How does it compare in color, flavor and texture to commercial mayonnaise that you have tasted before? What changes could be made to the formula or process to improve its quality? (10 points)
  6. Research and draw the structure of lecithin and explain why it has an amphiphilic nature (10 points)
Courtney Simons
Administrator
Courtney Simons is a food science professor. He holds a BS degree in food science and a PhD in cereal science from North Dakota State University.
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