No person shall sell or have in his possession for the purpose of sale or for use as an ingredient in the preparation of an article of food for sale a mixture of ghee or butter and any substance (a) prepared in imitation of or as a substitute for ghee or butter, or (b) consisting of or containing any oil or fat which does not conform to the definition of ghee :
Provided where a mixture prohibited by this rule is required for the preparation of an article of food, such mixture shall be made only at the time of the preparation of such article of food.
