(a) An acidifying agent consisting of one or any mixture of two or more of the following: a vinegar, lactic acid, citric acid, acetic acid, phosphoric acid, or other acidifying agents approved by the director may be used in pasteurized process cheese in such quantity that the pH of the pasteurized process cheese is not below 5.3; and in pasteurized process cheese food in such quantity that the pH of the pasteurized process cheese food is not below 5.0; and in pasteurized process cheese spread in such quantity that the pH of the pasteurized process cheese spread is not below 4.0; and in cold pack cheese and cold pack cheese food in such quantity that the pH of the finished product is not below 4.5. When acidifying agents are used in cold pack cheese, such cheese shall be labeled with the name of the acidifying agent followed with the statement “added as a chemical preservative.” Pasteurized process cheese spread and cold pack cheese food acidified below the pH 5.0 shall be labeled with the name of the acidifying agents other than vinegar followed with the statement “chemical preservative added.”