Oil and Vinegar Do Mix…When You Have an Emulsifier *
|Time Required||Very Short (≤ 1 day)|
|Material Availability||Readily available|
|Cost||Very Low (under $20)|
AbstractIn this cooking and food science fair project, you will explore the role of proteins as emulsifying agents. Emulsifying agents are substances that are soluble in both fat and water and enable fat to be uniformly dispersed in water as an emulsion. Foods that consist of such emulsions include butter, margarine, salad dressings, mayonnaise, and ice cream. Emulsifying agents are also used in baking to aid the smooth incorporation of fat into the dough and to keep the baked goods tender. Natural emulsifying agents used in foods include agar, albumin (egg whites), alginates, casein, egg yolk, gums, Irish moss, and lecithin. Here is a procedure to test albumin, which is a protein found in egg whites, as an emulsifier.
Collect three glass jars with tops. Add 1/2 cup of vegetable oil (or olive oil), 1/2 cup of white vinegar, and one drop of food dye to each jar. The dye stays in the vinegar and makes it easier to see the boundary between the oil and vinegar. (A chemist would explain this step as the dye partitions into the aqueous phase).
Number the jars 1 to 3. Separate the white and yolk of an egg (keep both parts). In jar #1, add 1 tablespoon of egg white and 1 tablespoon of water; in jar #2, add 2 tablespoons of egg white; in jar #3, add 2 tablespoons of water. Shake the jars to mix the oil and vinegar. Measure how long it takes for a clear boundary to form between the oil (top layer) and the vinegar (bottom layer). A good emulsifying agent will keep the oil and vinegar mixed together, delaying the appearance of a clear boundary. Try variations with more egg white, or with other emulsifiers, such as egg yolk, balsamic vinegar instead of white vinegar, etc.
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Last edit date: 2017-07-28
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