The ability to join fat-based and water-based liquids makes eggs an ideal emulsifier.
Oil and water just don't mix--unless you add an emulsifier. An emulsifier is a substance that has the unique ability of joining fat-based and water-based liquids. Without emulsifiers, we would not have ice cream, cake, mayonnaise or many of the cosmetics we use. One of the most readily available emulsifiers is eggs. You can use eggs in the classroom to demonstrate the power of emulsifiers to bind together oil-based and water-based solutions.
Make a Hollandaise Sauce
Eggs create an emulsion in Hollandaise sauce that prevents the lemon juice and butter from separating.
Demonstrate the emulsifying properties of eggs by making Hollandaise sauce. Beat three egg yolks in a pan with a wire whisk. Beat in 1 tablespoon lemon juice, 1 tablespoon water, 1/4 teaspoon salt and a pinch of white pepper. Heat over low heat and stir until the mixture is smooth and creamy. This combined mixture demonstrates the first emulsion of the sauce. Remove it from heat and beat in 6-8 ounces of melted butter, a quarter teaspoon at a time. As the sauce thickens, beat in the remaining butter by half tablespoons. This creates the final emulsion, which distributes the butter evenly throughout the sauce.
Experiment with Oil and Vinegar
Oil-and-vinegar salad dressings must be shaken before being poured to mix the two ingredients.
Fill three glass jars with lids each with 1/2 cup vegetable oil, 1/2 cup white vinegar and a drop of food dye to make it easier to see the division between the oil and vinegar. Add 1 tablespoon of egg white and 1 tablespoon of water to the first jar, 2 tablespoons of egg white to the second jar, and 2 tablespoons of water to the third jar. Cap and shake all three jars then time how long it takes for the boundary between the water and vinegar to reappear. A good emulsifier, such as an egg white, will keep the vinegar and water mixed together longer. Add different variations of egg white, or egg yolk, to determine the most effective emulsifier.
Make Ice Cream
Ice cream was originally made using eggs as the emulsifier.
Demonstrate the emulsifying properties of egg yolks by making ice cream. Make vanilla ice cream with 2 quarts of cream, 1 1/2 cups of instant , 2 cups sugar, 1 (1/4 oz.) package of gelatin, one large egg and 2 teaspoons vanilla. Heat the cream in a double boiler then beat in the egg and skim-milk powder. Mix the gelatin with the sugar and add to the liquid, mixing constantly. The resulting cream mixture demonstrates the power of the egg to create an emulsion between the water and the non-fat milk solids of the skim-milk powder and the fat in the cream. Place the top of the double boiler in cold water to cool rapidly. Store the mixture overnight in the refrigerator. Remove it from the refrigerator and stir in the vanilla. Pour the mixture into a hand-crank or electric ice cream freezer. Add crushed ice around the freezer can and sprinkle it with salt. Freeze the mix for 20-30 minutes.
Tags: skim-milk powder, between water, , Demonstrate emulsifying, Demonstrate emulsifying properties
