Cal. Food and Agricultural Code - FAC § 35941. Section 35941.
Homogenized market milk is market milk which has been subjected to a process or treatment in such manner as to insure the breakup of the fat globules to such an extent that no visible cream separation will occur on the milk after 48 hours storage at a temperature of between 40 and 50 degrees Fahrenheit and the fat percentage of the top 100 cc. of milk in a quart bottle, or proportionate volumes in containers of other sizes, does not differ by more than 10 percent of itself from the milk fat percentage of the remaining milk as determined after thorough mixing. In removing the top 100 cc. of milk, it shall be siphoned off. Homogenized market milk shall otherwise conform to all requirements for market milk.