Mich. Comp. Laws § 288.718

Sec. 158. (1) The department may require a plant to provide chlorinating facilities for butter wash water. (2) A person who owns or operates a plant shall take all necessary precautions to prevent contamination of products. (3) In the packaging of butter and related products, a plant shall use commercially acceptable containers or packaging material that will protect the quality of the contents in a manner acceptable to the department. All cups or tubs containing 2 pounds or less shall have tops or covers that extend over the lip of the container to protect the product from contamination during subsequent handling.