Cheese Molecule

What gives annatto its orange color?

As we’ve discussed before, cheesemakers can add annatto (or more specifically annatto extract) to their milk in order to make orange cheeses like cheddar. (much to the chagrin of East-coasters) This post is a brief discussion of the main pigment(s) found in annatto extracts; namely norbixin and bixin.

Norbixin is the main pigment in annatto extract that is of interest to cheesemakers. It is water soluble, meaning it will easily mix with water. In cheese making, annatto extract is added to milk, which is predominantly water, so water solubility is important.

The structure of norbixin. Visualized using 3Dmol.js
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Annatto extract does not start its life containing mostly norbixin. It actually starts off containing mostly bixin, which is not very water soluble. Annatto extract manufacturers have to transform bixin into norbixin. That is accomplished by treating the extract with an alkaline agent, like potassium hydroxide or sodium hydroxide. This converts bixin into norbixin via saponification.

Bixin Norbixin

Annatto extract usually contains norbixin (and its salts) which are derived from bixin


This process is a lot more complicated than I’ve stated above. In many cases, annatto extract is not just norbixin. It contains a mixture made up mostly of various norbixin salts (like potassium norbixinate for example).