Like dissolves like. A polar substance will not dissolve a nonpolar substance. In the case of oil and vinegar, the vinegar is polar and more dense than the oil, so it settles on the bottom of the container. The oil is nonpolar and less dense, so it doesn't dissolve in the vinegar, and it floats on top. Why does an oil-and-vinegar salad dressing have two separate layers? Did the mixtures with the emulsifiers take more or less time to separate than your control? Is this what you expected?
Based on your observations of separation time, which emulsifier would you recommend using for making salad dressing? How would you expect the separation time to change if you added more emulsifier?
What about if you added more oil than water? Lemon juice is mostly citric acid and water. Would you expect it to mix better with olive oil or vinegar? Why or why not? Look for recipes for other salad dressings or vinaigrettes online. For each, try to identify which ingredient is the polar molecule hydrophilic , which ingredient is the non-polar molecule hydrophobic , and which ingredient is the emulsifier.
Lab protocol and materials list. Emulsifier data sheet. Secrets of the Sauce. Meet the Writer Ariel Zych. Explore More. Get the Recipe: Italian Dressing Mix. Your base can be changed to give your dressing a different flavor. For an Asian-inspired dressing, use rice vinegar, a shot of soy sauce, cilantro instead of parsley, and a slice of fresh ginger. Blend in a neutral oil like canola or avocado.
For a Spanish flair, use sherry vinegar, season with paprika. For Tex-Mex, use lime juice, add a pinch of chile powder, cilantro instead of parsley, and a neutral oil. By Robin Asbell December 14, Pin FB Share. Fresh Raspberry Balsamic Vinaigrette. Credit: Marianne. The easiest way to achieve a fully emulsified vinaigrette is in the food processor. At this point, you're probably thinking what I'm thinking: this is all very neat, but what difference does it make to my salad?
Good question. My next order of business was to examine what happens when vinegar and oil are added to greens. I'd always been under the impression and I'm not the only one that a dressed salad eventually wilts because the acid in the vinegar attacks the leaves.
Turns out that vinegar is not the culprit at all. The greens dressed with plain oil wilted significantly faster than those dressed in vinegar. In fact, the vinegar-coated greens fared pretty much just as well as those dressed in water! The truth is that salad greens, like any leaf, spend their time exposed to the elements, and as such, need to protect themselves from the rain.
They do this via a thin, waxy cuticle. It's like a little built-in raincoat for the leaf. On the other hand, this oily cuticle makes it very easy for the olive oil to penetrate the spaces between cells dogs and dogs stick together, remember , causing damage to the leaf.
As a further test, I then dressed another batch of salad greens in a vinaigrette that I constructed without any surfactant i. I took an up-close-and-personal look at the results, and what I saw was this above, right : drops of vinegar suspended above the surface of the leaf by larger drops of oil, like little blobs sitting in bean bag chairs.
Lifting the leaf up between my fingers prompted a cascade of vinegar to tumble back into the bowl, while the oil continued to cling tenaciously to its surface. A ha , I thought. This must be the key. I set up one last experiment, this time dressing two 1-ounce portions of salad side-by-side. The second was dressed with the same mixture, minus the mustard. After tossing the greens, I immediately placed them inside funnels, which I set over a couple of small glasses in order to catch any drippings.
Almost immediately, the non-mustardy batch on the right started dripping a steady trickle of vinegar into the cup, while the well-emulsified dressing on the left stayed firmly in place.
After only ten minutes, the right cup had nearly a full teaspoon of vinegar collected in its bottom—almost the entire amount that I had put on the salad in the first place—and was starting to drip a few drops of oil as well. The cup on the left had shed at most a dozen drops. Unless you emulsify your vinaigrette, you end up with a pile of leaves dressed in oil, and a pool of vinegar at the bottom of the salad bowl, completely destroying the flavor of the sauce.
An emulsified vinaigrette however, uses the power of surfactants to help both oil and vinegar cling tightly to the leaves. Balanced flavor in every mouthful.
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