Q. When I make mayonnaise at home it is really yellow from the egg yolks, but when I buy it in a shop it is very white. Why isn’t the shop mayonnaise yellow, do they bleach it or something?
Asks Sophie in London.
A. Bleach would be a pretty extreme way of whitening and even ‘bleached flour’ isn’t actually bleached. They add a ‘bleaching agent’ to oxidise the outside of each grain, but I digress…
Commercially produced mayonnaise is actually whiter than the stuff that you might make at home for a number of reasons, I have decided to call them the three W’s:
Water – You don’t add water when you make mayo at home but many commercial producers (like Hellman’s) do. It’s often the second ingredient listed by volume after the oil.
Whites – You almost certainly use only yolks but commercial mayonnaise often uses whole eggs in place of or in addition to yolks.
Whisking – The more air that you get into your mayo the whiter it appears due to oxidisation. Mayo produced in a factory uses massively powerful mixers that beat a lot more air into the mixture than your puny home blender/food processor/hand and whisk can manage.
It also depends on the oil that you use, some add more colour than others and where the eggs come from. Compare the colour of a yolk from an organic corn fed free range chicken and one from the cheapest supermarket egg and you will see what I mean.