Whenever by any act of Congress or any rule or regulation adopted thereunder the agency is authorized to accept, receive, or purchase for resale from the federal government or any agency thereof, or any state agency at the request of, and with the approval of, the Department of General Services, any food commodities and to provide for its disposition or resale, it is authorized to do so and is vested with all necessary power and authority to accomplish the acceptance, purchase, receipt, disposition and resale. The agency is hereby exempted from Article 2 (commencing with Section 14790) of Chapter 6 of Part 5.5 of Division 3 of Title 2 of the Government Code.