The Director of Public Health and all his authorized officers, agents and employees shall have the right at any time to take samples of milk, cream or milk food products and imitations thereof from any person storing, selling, exposing for sale, exchanging, transporting, delivering, or distributing in the City and County of San Francisco, or shipping into said City and County milk, cream or milk food products and imitations thereof, provided that such samples shall not exceed in quantity one quart of milk and one quart of cream or milk food product or imitation thereof at any one time.