(a) Whenever in the judgment of the Commissioner such action will promote honesty and fair dealing in the interest of the consumers, the Commissioner shall promulgate regulations fixing and establishing for any food or any class of food a reasonable definition and standard of identity and, if applicable, a reasonable standard of quality and fill of container.

(b) In prescribing a definition and a standard of identity for any food or class of food in which optional ingredients are permitted, the Commissioner shall, for the purpose of promoting honesty and fair dealing in the interest of consumers, designate the optional ingredients which shall be named on the label. The definitions and standards so promulgated shall conform so far as practicable to the definitions and standards promulgated under authority of the federal act.