Salad Dressing

This page was written by Dr.  John Michael Kaiser.

      How does salad dressing work?


      The secret behind salad dressing is related to many chemical situations that you encounter in your household and have no idea about the processes that are involved in "your daily life".  Let us use the example of "Cesar Salad" dressing to start off with.  Upon approaching a bottle sitting on a shelf in a Grocery Store, you might see the appearance of "3 distinct liquid layers" in the bottle.  

      Let us extend this example and assume that you have a small child with you.  After noticing that there are "3 distinct liquid layers" in the bottle, you hand it to your suddenly "screaming" child to "shut them up."  After a few minutes, you might pick up that same bottle to reconsider these "3 distinct liquid layers" and notice now that the "distinguishable liquid layers" are gone....and ask yourself what happened to them?  You might even make the following observations in question:

           1) There has been no change in volume...
           2) Presumably, there has been no change in composition?
      This leads you to the following question:  What happened to the "3 distinct liquid layer"?

      The answer is this, are you ready.........
       In the middle of the "3 distinguishable liquid layers--which equates to the 'middle layer' is a 'chemical' that has the same properties as your laundry detergent.

       The reason why you have "3" layers of liquid instead of a uniform layer is similar to the reason that "oil" will not mix  with " water.  There exists chemical properties with each layer that are defined as follows:

         1) Layer 1-- oil---oily substance--(with a lower density of water---BUT DOES NOT LIKE
         2) Layer 2-- an "Emulsifier"--a detergent--(a substance that has both chemical properties of
                                water and oil)
         3) Layer 3--Water--(a substance that does not attract oil or its counterparts)

       xx Right about now, you might be asking what is the point of all of this.....?  

      Well, the "Emulsifier" has the chemical properties that both your "water" layer "likes" and that the "oil" layer enjoys...therefore, upon "shaking and mixing the solution, you have a uniform layer!!!!!!

      I encourage you to experience this simple phenomenon the next time you enter the "grocery store."  Try it, go to the salad dressing aisle and pick up a bottle and mix it up and watch/wait for it to separate back into "3 distinct liquid layers"...Note: I am not to blame if you wait for hours for it to return to "equilibrium" which I will discuss in a future post.  Cheers!