Every now and then, when I pop over to my grandparents' house, they make sure to give me a glass (or two) full of fresh milk (or "whole milk" if you will) and then proceed to pamper me for the rest of the day.
Now, it suddenly struck me that the fresh milk I get over there actually has this really faint yellow tinge, as opposed to the skimmed milk I get at the store which is almost pure white.
I did try Googling this up, but I can't seem to find anything on what imparts the yellow tinge to fresh milk.
So,
What substance/pigment is responsible for the yellow tinge associated with fresh milk?
Answer
The main substances that cause the yellowish color of the milk are carotenoids [1]. The main carotene involved is the beta-carotene coming from the feed that cows eat.
Some studies have been carried on and it has been noticed that the milk with a more yellow tinge was collected during late spring and early summer when carotene levels are at a maximum [2] unfortunately for this reason in many products as mozzarella they add titanium oxide. The amount of Riboflavin is too little compared to that of beta-carotene and generally gives a slightly green-ish tinge to the milk as reported here and here [3].
- P. F. Fox, Fundamentals of Cheese Science,p. 13
- Kosikowski, Frank V., and David P. Brown. "Application of titanium dioxide to whiten mozzarella cheese." Journal of Dairy Science 52.7 (1969): 968-970.
- Marion Eugene Ensminger,Audrey H. Ensminger,Foods & Nutrition Encyclopedia, 2nd Edition, Volume 1,p. 798
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