The appeal shall be submitted to the secretary in writing within the time period provided in the letter of notification of the adverse action or within 30 days of receipt of the letter of notification of the adverse action, whichever is later. The appeal shall be considered filed on the date the appeal is received by the secretary. An adverse action shall become final and nonappealable unless an appeal is timely filed. The secretary’s proceeding shall, insofar as practicable, comply with the Administrative Procedure Act, Chapter 5 (commencing with Section 11500) of Part 1 of Division 3 of Title 2 of the Government Code, except that a Department of Food and Agriculture hearing officer may be used.