Almost every salad recipes I've read needs some oil. What's its effect on vegetables? How does it change the flavor?

If oil is not used for the taste, why is it necessary for salads?

2 Answers 2


Here are a couple reasons why (for which I know) oil is used on salads:

  1. Oil caries in fat soluble aromas (often we use aromatic oils like olive oil, pumpkin seed oil, walnut oil, and so on, that are all very aromatic) and balances out other components (like vinegar or lime juice or some strong tasting veggies).
  2. it adheres to the surface of many leaves/vegetables better than water/vinegar (cause it breaks into the waxy leaf cuticle), so the dressing coating gets evenly distributed over the salad, you can use another thicker substance that clings to the leafs (like yoghurt) for this purpose instead.
  3. in thicker vinaigrettes/dressings it serves as a thickener, as by mixing with vinegar it builds an emulsion (like in aioli the oil usually represents the continuous phase of the traditional vinaigrette - water-in-oil emulsion, where many modern vinaigrettes reverse the ratio - oil-in-water emulsion, or use some other fats rather than oil).

And as already noted, it is not necessary for salads, you can use just lime juice (like in some thai salads), boiled dressing (that is thickened with starch), stock reduction, fruit/vegetable purees, yoghurt dressings or something else that does not require oil (e.g. I have made slightly pickled japanese salads that only required some vinegar and brine and the main aromas came from the veggies).

Also, I found this to answer "What's its effect on vegetables?":

McGee, on Food&Cooking says:

Oil seeps through the waxy leaf cuticle and spreads into the leaf interior, where it displaces air and causes the leaf to darken and its structure to collapse.


All food needs some presence of fat in order to be have a desirable taste. Meats don't need any added fat but green leafy vegetables have almost no fat. Green vegetables are rich in vitamin A and K which are only soluble in fat. So it stands to reason that the combination of olive oil with lettuce would have a pleasant taste.

  • But what's the difference in taste if I don't add oil to vegetables? Are they dry or something? Jul 20, 2013 at 0:38
  • 1
    Vegetables tend to be bitter by themselves. Oil and vinegar helps to cut that bitterness. Leaving the vegetables in the oil will cause them to go limp and is undesirable. This is why you want to wait until it is time to serve the salad to dress the lettuce.
    – cspirou
    Jul 20, 2013 at 0:45
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    It simply is not true that food needs some fat to taste good. Consider for example, lemonade, which most people consider to taste good, yet which is fat free in most recipes (unless there is some traces from the zest, which is not always used). Furthermore, if the vegetables are rich in vitamins that are only fat soluble, it stands to reason that they contain sufficient fat to dissolve the load of such vitamins that they carry. Olive oil may taste pleasant with vegetables, but that has nothing to do with the things you have said.
    – SAJ14SAJ
    Jul 20, 2013 at 2:08
  • @ SAJ14SAJ - Lettuce has zero grams of fat. Can you cite me anything that says lettuce contains fat?
    – cspirou
    Jul 20, 2013 at 2:14
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    I also disagree with the first sentence. Fat always tastes good, but it is a logical fallacy to infer from it that food without fat always tastes bad. As for the "fat soluble vitamins", they are actually not fat soluble but lipophilic, which means that they dissolve in non-polar solvents including, but not limited to, fat. So there is no chemical reason for a plant which contains them to also contain fat.
    – rumtscho
    Jul 21, 2013 at 13:15

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