Cal. Food & Agric. Code § 36991

Frozen yogurt is a frozen dairy product. It shall be made from milk, with or without added milk solids, flavoring, or seasoning, which has been pasteurized and afterwards fermented by one or more strains of Lactobacillus bulgaricus, including yogurt strains, Streptococcus thermophilous and Lactobacillus acidophilus. It shall not be pasteurized following fermentation. It shall contain not more than 10 coliform bacteria per gram, contain not more than 10 colonies per gram each of molds, yeasts, and other fungi, and be free of any other objectionable bacteria that may impair the quality of the product.