Why Is Mayo White If Yolks Are Yellow?
We live our lives without questioning so many things. You've probably never wondered if the wasabi you very much enjoy with your sushi is real (it probably isn't), or if the "healthy" cereal you enjoy in the mornings is actually unhealthy.
We even see the bottle of mayo in our fridge each day and never question why it's some shade of white when egg yolks are yellow. Beaten whole eggs are not white, so why would something that is made of mostly eggs be entirely white?
Legendary author Stephen King has pondered this question as well. "Operating under the theory that the only stupid question is the one you don't ask (a postulate with which some may disagree), I pose this: Why is mayonnaise white?" King asked in a tweet that inspired a storm of discussion.
Thankfully, the answer isn't elusive. Store-bought mayo is white because of the ingredients in it, as well as the method used to make it.
Many commenters pointed out, and proved with photos, homemade mayonnaise is often a much deeper yellow color than the store-bought. There are several reasons for this. As it turns out, most commercial mayonnaise doesn't have much egg in it - Hellman's Real Mayonnaise has 8.9% egg and egg yolk. Another factor is the high oil content, which can be well over 70%. Since mass-produced mayonnaise is beaten and stirred to the point that it's more aerated than something you would make at home, the result is less-pigmented mayo with a thicker consistency.
The oil in mayo also reflects light, giving it a whiter appearance. Most store-bought brands also include far more ingredients than home-made recipes, often including preservatives, which can affect the color of the final product.
In conclusion, the reason your homemade mayo isn't so white is that it's not as aerated and typically uses more eggs than mass-produced mayo.