When I see mayonnaise in the store, I always wonder why it is so white. The typical recipe for mayonnaise starts with egg yolks, adds vinegar or lemon juice, salt, pepper, mustard (I prefer to use ground mustard seeds). After mixing these ingredients, you start adding vegetable oil drop by drop by drop until you have a thick emulsified dressing.
And this is what my mayonnaise looks like. Starting with egg yolks this rich and bright, the mayonnaise I make at home always comes out quite yellow. So what are the food companies doing to make their mayonnaise so white?
A look at their ingredients reveals the answer. A check of commercial mayonnaise reveals that they are adding water to their mayonnaise. In some, water is even the first ingredient, which means there is more water than any other ingredient.
Mayonnaise recipes usually call for a ratio of one egg yolk per cup of oil. However, by using water, you can actually emulsify up to a dozen cups of oil with just one egg yolk. Commercial mayonnaise makers also often use the whole egg, not just the egg yolk. As a result, the ratio of egg yolk to oil is much less than in home made mayonnaise which is why their mayonnaise is so white.
What Makes Store Brand Mayo White ~ Stack Exchange