Butterfat or milkfat is the fatty portion of milk. Milk and cream are often sold according to the amount of butterfat they contain.
The fatty acids of butterfat are typically composed as follows (by mass fraction):
Butterfat is a triglyceride
(a fat) derived from fatty acids such as myristic, palmitic, and oleic acids.
 Fatty acids vs triglycerides
As shown above, the composition of fats in milk is usually discussed in terms of the fatty acids. Fatty acids do not occur as such in milk (and rarely in any food). Instead, they are incorporated into compounds called triglycerides.
 U.S. Standards
In the U.S., there are federal standards for butterfat content of dairy products. Commercial products generally contain the minimum legal amount of fat.
- skim milk contains less than 0.5% fat, typically 0.1%
- lowfat milk contains between 0.5–2% fat; 1% and 2% varieties are widely marketed
- whole milk contains at least 3.25% fat
- dry curd and nonfat cottage cheese contain less than 0.5% fat
- cottage cheese contains at least 4% fat
- lowfat cottage cheese contains 0.5–2% fat
- Cheddar cheese contains at least 50% fat relative to the total solids
- Swiss cheese contains at least 43% fat relative to the total solids
- Frozen desserts
- ice cream contains at least 10% fat
- lowfat ice cream, also called ice milk, contains no more than 2.6% fat
- frozen custard, like ice cream, contains at least 10% fat, but it also must contain at least 1.4% egg yolk solids
- sherbet contains 1–2% fat
- Butter (including whipped butter) contains at least 80% fat
 See also
- ^ National Research Council, 1976, online edition Fat Content and Composition of Animal Products, Printing and Publishing Office, National Academy of Science, Washington, D.C., ISBN 0-309-02440-4; p. 203
- ^ a b The quote values vary by 1-3% according to the source: Rolf Jost "Milk and Dairy Products" Ullmann's Encyclopedia of Industrial Chemistry, Wiley-VCH, Weinheim, 2002. doi:10.1002/14356007.a16_589.pub3
- ^ United States Department of Agriculture Agricultural Marketing Service
- ^ USDA Commercial Item Description: Milks, Fluid (2001).
- ^ USDA Specifications for Cream Cheese, Cream Cheese with other Foods, and Related Products (1994).
- ^ United States Department of Agriculture Standard for Ice Cream (1977).
- ^ USDA Commercial Item Description: Cream, Eggnog, Half-and-half, and Sour Cream (2002).