Every producer subject to this chapter and every vintner who purchases winegrapes from or processes winegrapes for producers shall maintain normal commercial records of all winegrapes grown for market or processed. The records shall be in simple form and contain information as the commission shall prescribe. The records shall be preserved for a period of two years and shall be offered and submitted for inspection at any reasonable time upon written demand of the commission or its duly authorized agent or, in the case of a local commission, by the secretary or his or her duly authorized agent. The local commission shall not serve as the secretary’s duly authorized agent for purposes of records inspection.